JP2012016149A - Photovoltaic power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic power generation device capable of efficiently selecting a secondary battery so as to maximize a generating capability of a solar battery and performing a charging/discharging operation so as to equalize a charging depth of the secondary battery.SOLUTION: A solar battery operating voltage decision unit 18 determines whether an operating voltage of a solar battery 11 by a maximum power point tracking control is in a middle range of voltages of the rated voltages of two secondary batteries 12 or not when a charging/discharging control for the secondary battery 12 is required during the maximum power point tracking control. A first secondary battery selection unit 19 selects the one secondary battery of which the rated voltage is closer to the operating voltage of the solar battery 11 when the operating voltage is determined to be out of the middle range of voltages. A second secondary battery selection unit 20 selects the one secondary battery 12 of which an output power is higher when the solar battery is operated by the maximum power point tracking control unit 23, when the operating voltage is determined to be in the middle range of voltages. A secondary battery connection unit 22 connects the selected secondary battery 12 with the solar battery 11 of a direct current system 14 in parallel by a switching circuit 13.

Description

  The present invention relates to a solar power generation apparatus in which a secondary battery is installed in parallel to a solar battery and performs an interconnection operation with a power system.

  A solar power generation device converts the direct current power of a solar cell into an alternating current with an inverter and operates in conjunction with an existing power system, so that it can be operated in the event of a disaster or system failure. In some cases, a secondary battery is installed in parallel via a switch circuit.

  When controlling the output of a solar cell, the switch circuit is opened to disconnect the secondary battery from the solar cell, the solar cell is subjected to maximum power tracking control (MPPT (Maximum Power Point Tracking) control), and the power system is connected via an inverter. Supply power.

  On the other hand, when charge / discharge control of the secondary battery is performed, the switch circuit is closed, and control is performed to supply power from the power system to the secondary battery via the inverter when charging, and from the secondary battery to inverter when discharging. The control which supplies electric power to an electric power system via is performed.

  When a solar battery and a secondary battery are simultaneously connected in parallel and controlled by a single inverter, the DC voltage of the DC system (DC voltage of the inverter) is governed by the voltage of the secondary battery. This is because the secondary battery has voltage source characteristics and very low internal impedance. When the DC voltage of the inverter is governed by the voltage of the secondary battery, the operating voltage of the solar battery is governed by the voltage of the secondary battery, and the maximum power tracking control (MPPT control) of the solar battery cannot be performed.

  Therefore, when the maximum power tracking control of the solar cell is performed, the switch circuit is opened to control the maximum power tracking of the solar cell, and when the secondary battery is connected to the inverter, the operation of the solar cell is stopped and the switching circuit is closed. The charging / discharging control of the secondary battery is performed.

  In place of the switch circuit, a DC chopper is connected between the secondary battery of the DC system and the inverter, and the DC voltage of the secondary battery is adjusted to the operating voltage of the solar battery by the DC chopper. In some cases, the DC voltage is controlled to be constant.

  Using a DC chopper, an inverter that generates power corresponding to the power output command value and a solar cell are connected, and a bidirectional DC / DC converter block is connected between the connection point between the solar cell and the inverter and the battery. Insert and control the voltage at the connection point between the solar cell and the inverter so that the generated power of the solar cell is maximized when the battery discharge command is generated, and the solar power is maximized when the battery charge command is generated. There is one in which the voltage at the connection point between the battery and the inverter is controlled to maximize the power generation capacity of the solar cell so that solar energy can be used effectively (see, for example, Patent Document 1).

JP-A-6-266457

  However, since the thing of patent document 1 controls the voltage of the connection point of a solar cell and an inverter using a bidirectional DC / DC converter block (DC chopper), a bidirectional DC / DC converter block is used. This increases the overall size and loss of the system.

  In order to efficiently perform the charge / discharge operation of the secondary battery while maximizing the power generation capacity of the solar cell without using a DC chopper, when giving priority to the power generation capacity of the solar battery, the maximum output of the solar battery In order to prioritize the charge / discharge operation of the secondary battery considering the balance of the charge depth of the secondary battery by connecting the secondary battery that can output the output power closest to the power in parallel to the solar battery of the DC system The secondary battery is connected in parallel to the solar battery so that the charging depth of the secondary battery is uniform.

  In that case, when there are a plurality of secondary batteries, it is necessary to efficiently select which secondary battery is a secondary battery that can output the output power closest to the maximum output power of the solar battery. .

  The object of the present invention is to efficiently select a secondary battery that can maximize the power generation capacity of the solar cell, and to charge and discharge the secondary battery so that the charging depth of the secondary battery is uniform. It is providing the solar power generation device which can be performed.

  The solar power generation device according to the invention of claim 1 is a solar battery that generates direct-current power by sunlight, two secondary batteries having different rated voltages, and two secondary batteries in parallel with the solar battery, respectively. A switching circuit connected to the solar battery, a secondary battery selection unit for selecting a secondary battery connected in parallel to the solar battery, and an alternating current system by converting direct current power of the solar battery and the direct current system of the secondary battery into an alternating current An inverter that converts the alternating current power of the alternating current system into direct current power and outputs the direct current power to the direct current system, and a controller that operates the solar cell and performs charge / discharge control of the secondary battery by the inverter A secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit, and the output power of the solar cell. Maximum power tracking control unit that performs maximum power tracking control so as to achieve maximum power, charging / discharging control unit that performs charging / discharging control of the secondary battery, and commands from the maximum power tracking control unit and the charging / discharging control unit And the secondary battery selection unit requires charge / discharge control of the secondary battery during the maximum power tracking control in the maximum power tracking control unit. Whether the operating voltage of the solar cell by the maximum power follow-up control is an intermediate voltage range that is not less than the smaller voltage value of the rated voltages of the two secondary batteries and not more than the larger voltage value. A secondary battery having a rated voltage close to the operating voltage of the solar cell when the operating voltage of the solar cell is determined not to be in the intermediate voltage range by the solar cell operating voltage determining unit and the solar cell operating voltage determining unit choose The first secondary battery selection unit and the solar cell operating voltage determination unit determine that the operating voltage of the solar cell is in the intermediate voltage range, the solar cells operate at the rated voltage of two secondary batteries, respectively. A second secondary battery that outputs a command to the maximum power follow-up control unit so as to operate the battery and selects a secondary battery having a larger output power when the solar battery is operated by the maximum power follow-up control unit A secondary battery selected by the first secondary battery selection unit or the second secondary battery selection unit of the secondary battery selection unit. Is connected in parallel to the solar cell of the DC system by the switch circuit.

  According to a second aspect of the present invention, there is provided the photovoltaic power generation apparatus according to the first aspect, wherein the second secondary battery selection unit of the secondary battery selection unit is an operation of the solar cell by the solar cell operating voltage determination unit. When it is determined that the voltage is in the intermediate voltage range, instead of operating the solar cell at the rated voltage of two secondary batteries, the solar in the vicinity of the operating voltage of the solar cell at that time An approximate curve of the output voltage-output power characteristics of the battery is calculated, and the secondary of which the output power increases when the operating voltage of the solar battery is set to the rated voltage of the two secondary batteries based on the approximate curve A battery is selected.

  A photovoltaic power generation apparatus according to a third aspect of the present invention is the solar power generation apparatus according to the first or second aspect, wherein when the output power of the inverter changes by a predetermined value or more during the operation of the secondary battery, An instruction to disconnect the secondary battery from the solar battery is output to the secondary battery connecting part, and an inverter output monitoring unit that activates the solar battery operating voltage determination part is included, and the secondary battery is searched again. Features.

  According to a fourth aspect of the present invention, there is provided a photovoltaic power generation apparatus according to the first or second aspect of the invention, wherein the control device includes two control devices when the charging depth of any of the two secondary batteries deviates from a predetermined range. A charge depth monitoring unit that outputs a connection switching command to the secondary battery connection unit so that the charge depth of the secondary battery is uniform, and the charge depth monitoring unit is requested by the charge / discharge control unit. In this case, a charge / discharge command for equalizing the charge depth of the two secondary batteries is output to the charge / discharge control unit.

  According to a fifth aspect of the present invention, there is provided a solar power generation apparatus comprising: a solar battery that generates direct-current power by sunlight; two secondary batteries having different rated voltages; and two secondary batteries in parallel with the solar battery. A switching circuit connected to the solar battery, a secondary battery selection unit for selecting a secondary battery connected in parallel to the solar battery, and an alternating current system by converting direct current power of the solar battery and the direct current system of the secondary battery into an alternating current An inverter that converts the alternating current power of the alternating current system into direct current power and outputs the direct current power to the direct current system, and a controller that operates the solar cell and performs charge / discharge control of the secondary battery by the inverter A secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit, and the output power of the solar cell. Maximum power tracking control unit that performs maximum power tracking control so as to achieve maximum power, charging / discharging control unit that performs charging / discharging control of the secondary battery, and commands from the maximum power tracking control unit and the charging / discharging control unit The secondary battery selection unit starts the maximum power follow-up control unit when starting the solar cell, and has a smaller rated voltage of the two secondary batteries. A solar cell starting unit that starts maximum power tracking control in an intermediate voltage range that is greater than or equal to a larger voltage value and maximum power tracking control of the maximum power tracking control unit started by the solar cell starting unit Temporarily determines the output power increase direction determination unit that determines the voltage direction in which the output power of the solar cell has increased, and the rated voltage secondary battery in the voltage direction determined by the output power increase direction determination unit. And whether the output power of the solar cell at the rated voltage of the secondary battery selected by the provisional selection unit is greater than the output power when the output power increase direction determination unit determines A solar cell output power determination unit that determines the output power of the solar cell at the rated voltage of the secondary battery selected by the temporary selection unit by the solar cell output power determination unit is determined by the output power increase direction determination unit The secondary battery is selected when it is determined that the output power is larger than the output power of the solar battery, and the output power of the solar battery at the rated voltage of the other secondary battery is selected by the provisional selection unit. And a final selection unit that compares the output power of the secondary battery and selects the secondary battery having the higher output power.

According to a sixth aspect of the present invention, there is provided a solar power generation apparatus including a solar battery that generates direct-current power by sunlight, three or more secondary batteries having different rated voltages, and three or more secondary batteries, respectively. A switch circuit connected in parallel to the solar cell, a secondary battery selection unit for selecting a secondary battery connected in parallel to the solar cell, and converting the DC power of the solar cell and the DC system of the secondary battery into alternating current An inverter that outputs to the AC system or converts AC power of the AC system to DC power and outputs the DC power, and a control device that operates the solar cell and performs charge / discharge control of the secondary battery by the inverter The control device includes a secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit, and the solar cell A maximum power follow-up control unit that performs maximum power follow-up control so that the force power becomes the maximum power, a charge / discharge control unit that performs charge / discharge control of the secondary battery, the maximum power follow-up control unit, and the charge / discharge control unit An inverter control unit that controls the inverter based on a command from the secondary battery, and the secondary battery selection unit performs charge / discharge control of the secondary battery during the maximum power tracking control in the maximum power tracking control unit. When necessary, it is determined whether or not the operating voltage of the solar cell by the maximum power tracking control is in an intermediate voltage range that is not less than the minimum value of the rated voltage of three or more secondary batteries and not more than the maximum value. When the solar cell operating voltage determining unit and the solar cell operating voltage determining unit determine that the operating voltage of the solar cell is not in the intermediate voltage range, a secondary battery having a rated voltage closest to the operating voltage of the solar cell is determined. select When the operation voltage of the solar cell is determined to be within the intermediate voltage range by the secondary battery selection unit and the solar cell operation voltage determination unit, the operation voltage of the solar cell A determination is made as to which operating voltage range is sandwiched between any two rated voltages of the rated voltages, and the solar cells are operated at the rated voltages of the two secondary batteries forming the operating voltage range, respectively. A command is output to the maximum power follow-up control unit, and a secondary battery having a larger output power when the solar battery is operated by the maximum power follow-up control unit is temporarily selected, and the temporarily selected second battery is selected. The output power of the solar cell, including the secondary battery temporarily selected for the output power of the solar cell at the rated voltage of the secondary battery outside the operating voltage range of the rated voltage of the secondary battery, is the maximum output. Second to select the secondary battery
A secondary battery selection unit, and the secondary battery connection unit of the control device is selected by the first secondary battery selection unit or the second secondary battery selection unit of the secondary battery selection unit A secondary battery is connected in parallel to the solar battery of the DC system by the switch circuit.

  According to a seventh aspect of the present invention, there is provided the photovoltaic power generation apparatus according to the sixth aspect, wherein the second secondary battery selection unit of the secondary battery selection unit operates the solar cell with the solar cell operating voltage determination unit. When it is determined that the voltage is in the intermediate voltage range, the rated voltage of any two of the rated voltages of the secondary batteries having three or more operating voltages of the solar battery is in the operating voltage range sandwiched between the rated voltages The output voltage of the solar cell in the vicinity of the operating voltage of the solar cell at that time, instead of operating the solar cell at the rated voltage of the two secondary batteries forming the operating voltage range -Calculate the approximate curve of the output power characteristics, and temporarily select the secondary battery whose output power is large when the operating voltage of the solar battery is the rated voltage of the two secondary batteries based on the approximate curve. Selected temporarily and its temporarily selected The output power of the solar cell at the rated voltage of the secondary battery that is outside the operating voltage range of the rated voltage of the secondary battery is obtained based on the approximate curve and includes the temporarily selected secondary battery. A secondary battery having a maximum output power is selected.

  A photovoltaic power generation apparatus according to an invention of claim 8 is the invention according to claim 6 or 7, wherein the control device, when the output power of the inverter changes more than a predetermined value during operation of the secondary battery, An instruction to disconnect the secondary battery from the solar battery is output to the secondary battery connecting part, and an inverter output monitoring unit that activates the solar battery operating voltage determination part is included, and the secondary battery is searched again. Features.

  According to a ninth aspect of the present invention, there is provided the photovoltaic power generation apparatus according to the sixth or seventh aspect of the invention, wherein the control device is configured such that when the charging depth of any of the three or more secondary batteries deviates from a predetermined range. Has a charging depth monitoring unit that outputs a connection switching command to the secondary battery connecting unit so that the charging depths of three or more secondary batteries are uniform, and the charging depth monitoring unit includes the charge / discharge control unit When there is a request from the charging / discharging control unit, a charging / discharging command for equalizing the charging depth of three or more secondary batteries is output to the charge / discharge control unit.

According to a tenth aspect of the present invention, there is provided a solar power generation apparatus including a solar battery that generates direct-current power from sunlight, three or more secondary batteries having different rated voltages, and three or more secondary batteries. A switch circuit connected in parallel to the solar cell, a secondary battery selection unit for selecting a secondary battery connected in parallel to the solar cell, and converting the DC power of the solar cell and the DC system of the secondary battery into alternating current An inverter that outputs to the AC system or converts AC power of the AC system to DC power and outputs the DC power, and a control device that operates the solar cell and performs charge / discharge control of the secondary battery by the inverter The control device includes a secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit, and the solar cell. Maximum power tracking control unit that performs maximum power tracking control so that output power becomes maximum power, charging / discharging control unit that performs charging / discharging control of the secondary battery, the maximum power tracking control unit, and the charging / discharging control unit An inverter control unit for controlling the inverter based on a command from the secondary battery selection unit, wherein the secondary battery selection unit activates the maximum power follow-up control unit when the solar cell is activated, and is rated for three or more secondary batteries. The solar cell activation unit that starts maximum power tracking control in an intermediate voltage range that is greater than or equal to the minimum value of the voltage and less than the maximum value, and the maximum power tracking control of the maximum power tracking control unit that is activated by the solar cell activation unit An output power increase direction determination unit that determines a voltage direction in which the output power of the solar battery has increased, and a rated battery that has a rated voltage in the voltage direction determined by the output power increase direction determination unit. A provisional selection unit that tentatively selects a secondary battery with the maximum output power of the solar cell at the output power of the solar cell at the rated voltage of the secondary battery selected by the provisional selection unit A solar cell output power determination unit that determines whether or not the output power is larger than the output power determined by the output power increase direction determination unit; and a secondary battery selected by the temporary selection unit by the solar cell output power determination unit When it is determined that the output power of the solar cell at the rated voltage is larger than the output power when determined by the output power increase direction determination unit, the secondary battery is selected, otherwise the output power increase Of the secondary batteries having a rated voltage in the opposite direction to the voltage direction determined by the direction determining unit, the output power of the solar battery at the rated voltage is the maximum output of the solar battery at the rated voltage of the secondary battery. Output power and the above A final selection unit that compares the output power of the secondary battery selected by the provisional selection unit and selects the secondary battery having the larger output power is provided.

  According to the invention of claim 1, when the charge / discharge control of the secondary battery is required during the maximum power tracking control, the operating voltage of the solar battery is the voltage value of the smaller of the rated voltages of the two secondary batteries. If it is in the intermediate voltage range that is lower than the larger voltage value above, select the secondary battery with the larger output power.If it is not in the intermediate voltage range, select the secondary battery with the rated voltage close to the operating voltage of the solar battery. Since it selects, the secondary battery which makes the solar cell the power generation capability to the maximum can be selected appropriately, and charging / discharging operation of the secondary battery can be performed.

  According to the invention of claim 2, when it is determined that the operating voltage of the solar cell is in the intermediate voltage range, instead of selecting the secondary battery with the larger output power, the solar cell at that time An approximate curve of the output voltage-output power characteristics of the solar cell near the operating voltage is calculated, and the output power increases when the operating voltage of the solar cell is set to the rated voltage of the two secondary batteries based on the approximate curve. Since the secondary battery is selected, it is possible to select the secondary battery that increases the output power more quickly than in the case of the invention of claim 1.

  According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, when the output power of the inverter changes more than a predetermined value during the operation of the secondary battery, the operating voltage of the maximum output of the solar battery Since the secondary battery is disconnected from the solar battery and the secondary battery is searched again, it can be operated near the maximum output of the solar battery in accordance with the fluctuation of the output power of the solar battery.

  According to the invention of claim 4, in addition to the effect of the invention of claim 1 or 2, when the charging depth of either of the two secondary batteries deviates from a predetermined range, the charging of the two secondary batteries is performed. Since charge / discharge control is performed so that the depth becomes uniform, the charge depth of the secondary battery can be made uniform.

  According to the invention of claim 5, when the solar cell is activated, the maximum power follow-up control unit is activated, and the intermediate voltage which is equal to or larger than the smaller voltage value of the rated voltage of the two secondary batteries and equal to or smaller than the larger voltage value. The maximum power tracking control is started in the range, and the secondary battery with the rated voltage in the voltage direction in which the output power of the solar cell is increased by the maximum power tracking control is provisionally selected, and the solar battery at the rated voltage of the secondary battery is selected. When the output power of the battery is larger than the output power when the voltage direction is judged, the secondary battery is selected, so that the operation at the rated voltage of the secondary battery for selecting the secondary battery is only required once. The secondary battery to be connected can be quickly determined. If the output power of the solar battery at the rated voltage of the temporarily selected secondary battery is smaller than the output power when the voltage direction is determined, the output power of the solar battery at the rated voltage of the other secondary battery Compared with, the secondary battery with the larger output power is selected, so the operation at the rated voltage of the secondary battery for selecting the secondary battery is performed twice, but the output power of the solar battery is always large. The secondary battery can be selected.

  According to the invention of claim 6, when charge / discharge control of any of the three or more secondary batteries is required during the maximum power tracking control, the operating voltage of the solar battery is that of the three or more secondary batteries. When the voltage range is between the minimum value and the maximum value of the rated voltage, the operation voltage of the solar cell is sandwiched between any two of the rated voltages of three or more secondary batteries. It determines whether it is in the voltage range, and outputs a command to the maximum power tracking control unit to operate each of the solar cells at the rated voltage of the two secondary batteries that form the operating voltage range, and the maximum power tracking control unit Temporarily select the secondary battery with the higher output power when the solar battery is operated by the rating of the secondary battery that is outside the operating voltage range of the rated voltage of the temporarily selected secondary battery The output power of the solar cell in voltage was calculated and temporarily selected Secondary batteries with the maximum output power of the solar battery including the secondary battery are selected. On the other hand, when not in the intermediate voltage range, the secondary battery with the rated voltage closest to the operating voltage of the solar battery is selected. Even when two or more secondary batteries are connected, it is possible to appropriately select a secondary battery that maximizes the power generation capability of the solar battery and to perform charge / discharge operation of the secondary battery.

  According to the invention of claim 7, when it is determined that the operating voltage of the solar cell is in the intermediate voltage range, the operating voltage of the solar cell is any two of the rated voltages of three or more secondary batteries. Instead of operating the solar cell at the rated voltage of the two secondary batteries forming the operating voltage range, determining whether the operating voltage range is sandwiched between the rated voltages, the solar cell at that time When the approximate curve of the output voltage-output power characteristics of the solar cell in the vicinity of the operating voltage is calculated and the operating voltage of the solar cell is set to the rated voltage of the two secondary batteries based on the approximate curve, the output power is large. The secondary battery is temporarily selected, and the output power of the solar battery at the rated voltage of the secondary battery that is outside the operating voltage range of the rated voltage of the temporarily selected secondary battery is used as an approximate curve. The secondary battery selected and temporarily selected In this case, the secondary battery having the maximum output power of the solar battery is selected, and therefore, the secondary battery having a large output power is selected even when three or more secondary batteries are connected. This can be done more quickly than in the case of the present invention.

  According to the invention of claim 8, in addition to the effect of the invention of claim 6 or 7, when the output power of the inverter changes more than a predetermined value during the operation of the secondary battery, the operating voltage of the maximum output of the solar battery Since the secondary battery is disconnected from the solar battery and the secondary battery is searched again, even if three or more secondary batteries are connected, the output power of the solar battery will fluctuate. Together, it can be operated near the maximum output of the solar cell.

  According to the invention of claim 9, in addition to the effect of the invention of claim 6 or 7, when the charge depth of any of the three or more secondary batteries deviates from the predetermined range, three or more two Since charging / discharging control is performed so that the charging depth of the secondary battery is made uniform, the charging depth of the secondary battery can be made uniform even when three or more secondary batteries are connected.

  According to the invention of claim 10, the maximum power follow-up control unit is activated at the time of starting the solar battery, and the maximum power follow-up is performed in an intermediate voltage range that is greater than or equal to the minimum value of the rated voltages of three or more secondary batteries and less than or equal to the maximum value. Control is started, and the secondary battery with the maximum output power of the solar battery at the rated voltage is provisionally out of the secondary batteries with the rated voltage in the voltage direction where the output power of the solar battery has increased by the maximum power tracking control If the output power of the solar cell at the rated voltage of the secondary battery is larger than the output power when the voltage direction is determined, the secondary battery is selected, so that three or more secondary batteries Even when is connected, a secondary battery to be connected can be selected.

  In addition, when the output power of the solar cell at the rated voltage of the temporarily selected secondary battery is smaller than the output power when the voltage direction is determined, the rating is applied in the direction opposite to the voltage direction in which the output power of the solar cell has increased. Among the secondary batteries with voltage, the output power of the solar battery at the rated voltage of the secondary battery with the maximum output power of the solar battery at the rated voltage and the output power of the secondary battery selected by the provisional selection unit Since the secondary battery with the larger output power is selected, the operation at the rated voltage of the secondary battery for selecting the secondary battery is performed twice, but the output power of the solar battery is always The larger secondary battery can be selected.

The block diagram of the solar power generation device which concerns on the 1st Embodiment of this invention. The VI characteristic of the solar cell when the operating voltage Vp of the solar cell of the photovoltaic power generation apparatus according to the first embodiment of the present invention is not in the intermediate voltage range of the rated voltages Va and Vb of the two secondary batteries, and The graph which shows an example of VP characteristic. The VI characteristic of the solar cell when the operating voltage Vp of the solar cell of the photovoltaic power generation apparatus according to the first embodiment of the present invention is in the intermediate voltage range of the rated voltages Va and Vb of the two secondary batteries And a graph showing an example of VP characteristics. When the operating voltage Vp of the solar battery of the photovoltaic power generation apparatus according to the first embodiment of the present invention is in the intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries, the approximate curve of the VP characteristic Explanatory drawing in the case of selecting a secondary battery using. The block diagram of the solar power generation device which concerns on the 2nd Embodiment of this invention. The graph which shows an example of the characteristic at the time of the VI characteristic and VP characteristic of the solar cell of the solar power generation device concerning the 2nd Embodiment of this invention changing. The block diagram of the solar power generation device which concerns on the 3rd Embodiment of this invention. The block diagram of the solar power generation device which concerns on the 4th Embodiment of this invention. The graph of the VI characteristic and VP characteristic of a solar cell which shows an example of operation | movement of the solar power generation device which concerns on the 4th Embodiment of this invention. The graph of the VI characteristic and VP characteristic of a solar cell which shows another example of operation | movement of the solar power generation device which concerns on the 4th Embodiment of this invention. The block diagram of the solar power generation device which concerns on the 5th Embodiment of this invention. When the operating voltage Vp of the solar cell 11 of the photovoltaic power generation apparatus according to the fifth embodiment of the present invention is not in the intermediate voltage range of the rated voltages Va, Vb, Vc of the three secondary batteries 12a, 12b, 12c The graph which shows an example of the VI characteristic and VP characteristic of the solar cell. When the operating voltage Vp of the solar cell 11 of the photovoltaic power generation apparatus according to the fifth embodiment of the present invention is in the intermediate voltage range of the rated voltages Va, Vb, Vc of the three secondary batteries 12a, 12b, 12c The graph which shows an example of the VI characteristic and VP characteristic of the solar cell 11 of. The operating voltage Vp of the solar battery 11 of the photovoltaic power generator according to the fifth embodiment of the present invention is the rated voltage Va of the two secondary batteries 12a and 12b within the intermediate voltage range (Va <Vp <Vc), Explanatory drawing in the case of selecting a secondary battery using the approximate curve of a VP characteristic in the range pinched | interposed between Vb. The block diagram of the solar power generation device which concerns on the 6th Embodiment of this invention. The graph which shows an example of the characteristic at the time of the VI characteristic and VP characteristic of the solar cell of the solar power generation device concerning the 6th Embodiment of this invention changing. The block diagram of the solar power generation device which concerns on the 7th Embodiment of this invention. The block diagram of the solar power generation device which concerns on the 8th Embodiment of this invention. The graph of the VI characteristic and VP characteristic of a solar cell which shows an example of operation | movement of the solar power generation device which concerns on the 8th Embodiment of this invention. The graph of the VI characteristic and VP characteristic of a solar cell which shows another example of operation | movement of the solar power generation device which concerns on the 8th Embodiment of this invention.

  Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a photovoltaic power generation apparatus according to the first embodiment of the present invention. This 1st Embodiment has shown the case where the two secondary batteries 12a and 12b are connected to the solar cell 11. As shown in FIG.

  That is, two secondary batteries 12a and 12b are connected to the solar cell 11 in parallel via the switch circuits 13a and 13b to form a DC system 14. The solar cell 11 is connected to the DC system 14 via the diode D, and power supply from the DC system 14 to the solar cell 11 is blocked. The rated voltages Va and Vb (Va <Vb) of the secondary batteries 12 a and 12 b are set to be smaller than the open circuit voltage Vo of the solar battery 11. The DC system 14 is connected to an AC system 16 on the power system side via an inverter 15.

  The secondary battery selection unit 17 selects the secondary batteries 12a and 12b connected in parallel to the solar cell 11, and includes a solar cell operating voltage determination unit 18, a first secondary battery selection unit 19, and a second The secondary battery selection unit 20 is configured. Further, the control device 21 controls the operation of the solar cell 11 by the inverter 15 or controls the charge / discharge of the secondary battery 12 selected by the secondary battery selection unit 17, the secondary battery connection unit 22, The maximum power follow-up control unit 23, the charge / discharge control unit 24, and the inverter control unit 25 are configured.

  First, the control device 21 will be described. The secondary battery connection unit 22 of the control device 21 connects the secondary batteries 12a and 12b selected by the secondary battery selection unit 17 in parallel to the solar cell 11 of the DC system 14 by the switch circuits 13a and 13b. The charging / discharging control unit 24 performs charging / discharging control of the secondary batteries 12a, 12b connected in parallel to the solar battery 11 of the DC system 14.

  When the secondary batteries 12 a and 12 b are not connected to the DC system 14, the maximum power tracking control unit 23 inputs the current Id and the voltage Vd of the DC system 14, for example, from the current operating voltage of the solar battery 11. The voltage is slightly increased and decreased, and a so-called hill-climbing method is used to search for an operating voltage with a large output power, and the maximum power tracking control is performed so that the output power P of the solar cell 11 becomes the maximum power Pmax. A command for the output power P to be the maximum power Pmax is output to the inverter control unit 25.

  In addition, when the secondary batteries 12a and 12b are connected to the DC system 14, the charge / discharge control unit 24 is configured so that the charge / discharge control unit 24 is determined by the rated voltages Va and Vb of the secondary batteries 12a and 12b. Is output to the inverter control unit 25.

  The inverter control unit 25 controls the inverter 15 based on commands from the maximum power follow-up control unit 23 and the charge / discharge control unit 24. Thereby, when the secondary batteries 12a and 12b are not connected to the DC system 14, the inverter 15 converts the maximum power Pmax of the solar battery 11 into AC and outputs it to the AC system 16, and the secondary batteries 12a and 12b. Is connected to the DC system 14, the output power P of the solar cell 11 determined by the rated voltages Va and Vb of the secondary batteries 12 a and 12 b is converted into AC and output to the AC system 16.

  Next, the secondary battery selection unit 17 will be described. The secondary battery selection unit 17 is activated by a charge / discharge command S for the secondary batteries 12a and 12b from the outside. The external charge / discharge command S is used when the secondary battery 12a, 12b needs to be charged / discharged during the maximum power tracking control by the maximum power tracking control unit 23. The voltage is input to the voltage determination unit 18. When the solar cell operating voltage determination unit 18 inputs an external charge / discharge command S, the operating voltage Vp of the solar cell 11 by the maximum power tracking control of the maximum power tracking control unit 23 and the ratings of the two secondary batteries 12a and 12b. The magnitude relationship with the voltages Va and Vb is determined. The operating voltage Vp of the solar cell 11 is detected as the voltage Vd of the DC system 14.

  For example, it is determined whether or not the operating voltage Vp of the solar battery 11 is a voltage in a range determined by the rated voltages Va and Vb of the two secondary batteries 12a and 12b (Va <Vp <Vb). Hereinafter, a voltage (Va <Vp <Vb) in a range determined between the rated voltage Va of the secondary battery 12a and the rated voltage Vb of the secondary battery 12b is referred to as an intermediate voltage range. The determination result in the solar cell operating voltage determination unit 18 is output to the first secondary battery selection unit 19 and the second secondary battery selection unit 20.

  In the first secondary battery selection unit 19, the operation voltage Vp of the solar cell 11 in the solar cell operation voltage determination unit 18 is not an intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries 12 a and 12 b (Vp> Va , Vp> Vb or Vp <Va, Vp <Vb), the secondary batteries 12a and 12b having a rated voltage close to the operating voltage Vp of the solar battery 11 are selected, and the selected secondary batteries 12a and 12b are selected. Is notified to the secondary battery connecting part 22 of the control device 21. This is because when the operating voltage Vp of the solar battery 11 is the maximum output operating voltage and the maximum output operating voltage is not in the intermediate voltage range of the rated voltages Va and Vb of the two secondary batteries 12a and 12b, the maximum output operating voltage is obtained. This is because the output power of the secondary battery 12 close to the voltage side increases.

  For example, when the relationship between the operating voltage Vp of the solar cell 11 and the rated voltages Va and Vb of the two secondary batteries is (Vp> Va, Vb), since Va <Vb, the solar cell 11 Since the operating voltage Vp is close to the rated voltage Vb, the secondary battery 12b having the rated voltage Vb is selected. On the other hand, when the relationship between the operating voltage Vp of the solar cell 11 and the rated voltages Va and Vb of the two secondary batteries is (Vp <Va, Vb), Va <Vb. Since the operating voltage Vp is close to the rated voltage Va, the secondary battery 12a having the rated voltage Va is selected. Thereby, the secondary battery 12 with larger output power can be selected.

  When the first secondary battery selection unit 19 determines that the operating voltage Vp of the solar battery Vp is equal to the rated voltages Va and Vb of the secondary battery (Vp = Va, Vp = Vb), the voltage is rated. The secondary battery 12 a or 12 b to be used as a voltage is selected, and the selected secondary batteries 12 a and 12 b are notified to the secondary battery connection unit 22 of the control device 21.

  Next, in the second secondary battery selection unit 20, the operation voltage Vp of the solar cell 11 in the solar cell operating voltage determination unit 18 is an intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries (Va < When it is determined that Vp <Vb), a command is output to the maximum power follow-up control unit 23 so that the solar battery 11 is operated with the rated voltages Va and Vb of the two secondary batteries 12a and 12b, respectively, and the maximum power The follow-up control unit 23 selects the secondary batteries 12a and 12b having higher output power when the solar battery 11 is operated at the rated voltages Va and Vb. Then, the selected secondary batteries 12 a and 12 b are notified to the secondary battery connection unit 22 of the control device 21.

  When the secondary battery connection unit 22 of the control device 21 receives the notification of the secondary batteries 12a and 12b selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20, the charge / discharge command S is issued. It is determined whether the charge command or the discharge command, and when the charge / discharge command S is a charge command, the secondary batteries 12a and 12b are connected in parallel to the solar cell 11 of the DC system 14 by the switching elements 26a1 and 26b1 of the switch circuits 13a and 13b. Connect to. On the other hand, when the charge / discharge command S is a discharge command, the secondary batteries 12a and 12b are connected in parallel to the solar cell 11 of the DC system 14 by the switching elements 26a2 and 26b2 of the switch circuits 13a and 13b. Then, the charge / discharge control unit 24 is notified that the secondary batteries 12 a and 12 b are connected to the DC system 14.

  When the charge / discharge control unit 24 receives information on the secondary batteries 12a, 12b connected to the DC system 14 from the secondary battery connection unit 22, the charge / discharge command S from the outside is sent to the secondary batteries 12a, 12b. Is output to the inverter control unit 25. Thereby, the inverter control unit 25 performs charge / discharge control according to the charge / discharge command S from the outside by the inverter 15.

  For example, when the charge / discharge command S is a discharge command for the secondary batteries 12a, 12b, the DC power from the secondary batteries 12a, 12b is converted into AC by the inverter 15 and supplied to the AC system 16 side. On the other hand, when the charge / discharge command S is a charge command to the secondary batteries 12a and 12b, the AC power of the AC system 16 is converted into direct current by the inverter 15 to charge the secondary batteries 12a and 12b.

  As described above, when the secondary batteries 12 a and 12 b are not connected to the DC system 14, the control device 21 performs maximum power tracking control so that the output power of the solar battery 11 becomes the maximum power, and the maximum power tracking is performed. When charge / discharge control of the secondary batteries 12a and 12b becomes necessary during the control, the secondary batteries 12a and 12b selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20 are connected to the direct current. The solar battery 11 is connected in parallel to the solar battery 11 of the system 14, and the solar battery 11 is operated with the rated voltages Va and Vb of the secondary battery, and charge / discharge control of the secondary batteries 12 a and 12 b is performed by the inverter 15.

  FIG. 2 shows the solar cell 11 when the operating voltage Vp of the solar cell 11 of the photovoltaic power generation apparatus according to the first embodiment of the present invention is not in the intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries. FIG. 2A is a graph showing an example of the V-I characteristic and the VP characteristic of the solar battery 11. FIG. 2A is a graph showing the solar cell 11 operating voltage Vp and the two secondary battery rated voltages Va and Vb. FIG. 2B is a graph showing an example of the VI characteristic curve C1 and the VP characteristic curve P1 when the relationship of (Vp> Va, Vb) is satisfied, and FIG. It is a graph which shows an example of VI characteristic curve C2 and VP characteristic curve P2 in case the relationship between Vp and the rated voltages Va and Vb of two secondary batteries is (Vp <Va, Vb). FIG. 2 shows a VI characteristic curve and a VP characteristic curve using the solar radiation intensity when the temperature of the solar cell 11 is constant as a parameter.

  As shown in FIG. 2 (a), when the solar radiation intensity is high, this is the optimum operating point at which the output power is maximum at the coordinate C11 on the VI characteristic curve C1, and the solar cell 11 follows the maximum power. The controller 23 is operating at the operating point C11, and the output power at that time is the maximum power P1max of the VP characteristic curve P1, and the operating voltage is Vp1.

  Since the operating voltage Vp1 of the solar cell 11 is not the intermediate voltage range (Va <Vp1 <Vb) between the rated voltages Va and Vb of the two secondary batteries 12a and 12b, the first secondary battery selection unit 19 The secondary battery 12b having the rated voltage Vb close to the operating voltage Vp1 is selected, and the selected secondary battery 12b is notified to the secondary battery connection unit 22. Thus, the solar cell 11 is operated at the rated voltage Vb of the secondary battery 12b, the operating point at that time is C1b, and the output power P of the solar cell 11 is P1b. The output power P1b of the solar cell 11 is larger than the output power P1a at the operating point C1a at the rated voltage Va of the other secondary battery 12a. Therefore, the secondary battery 12b can be operated while maximizing the power generation capability of the solar battery 11.

  Next, as shown in FIG. 2 (b), when the solar radiation intensity is small, it is the optimum operating point at which the output power is maximum at the coordinate C21 on the VI characteristic curve C1, and the solar cell 11 The maximum power follow-up control unit 23 is operating at the operating point C21, the output power at that time is the maximum power P2max of the VP characteristic curve P2, and the operating voltage is Vp2.

  Since the operating voltage Vp2 of the solar cell 11 is not an intermediate voltage range (Va <Vp2 <Vb) between the rated voltages Va and Vb of the two secondary batteries, the first secondary battery selection unit 19 The secondary battery 12a having the rated voltage Va close to Vp2 is selected, and the selected secondary battery 12a is notified to the secondary battery connection unit 22. Thus, the solar cell 11 is operated at the rated voltage Va of the secondary battery 12a, the operating point at that time is C2a, and the output power P of the solar cell 11 is P2a. The output power P2a of the solar cell 11 is larger than the output power P2b at the operating point C2b when the other secondary battery 12b is at the rated voltage Vb. Therefore, the secondary battery 12a can be operated while maximizing the power generation capability of the solar battery 11.

  Thus, during the maximum power follow-up control of the solar battery 11, charge / discharge control of the secondary batteries 12a and 12b is necessary, and the operating voltage Vp of the solar battery 11 is equal to the rated voltages Va and Vb of the two secondary batteries. When not in the intermediate voltage range (Va <Vp <Vb), it is possible to maximize the power generation capacity of the solar cell 11 simply by selecting the secondary batteries 12a and 12b having the rated voltages Va and Vb close to the operating voltage Vp of the solar cell 11. The secondary batteries 12a and 12b connected to the solar battery 11 can be charged and discharged while being exhibited. That is, it is possible to easily determine which secondary battery 12a, 12b is selected.

  FIG. 3 shows a solar cell in the case where the operating voltage Vp of the solar cell 11 of the photovoltaic power generation apparatus according to the first embodiment of the present invention is an intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries. It is a graph which shows an example of 11 VI characteristics and VP characteristics. FIG. 3 shows a VI characteristic curve and a VP characteristic curve using the solar radiation intensity when the temperature of the solar cell 11 is constant as parameters, and the solar radiation intensity is shown in FIGS. 2 (a) and 2 (b). ) In the middle.

  As shown in FIG. 3, this is the optimum operating point at which the output power becomes maximum at the coordinate C31 on the VI characteristic curve C3, and the solar cell 11 is operated at the operating point C31 by the maximum power tracking control unit 23. The output power at that time is the maximum power P3max of the VP characteristic curve P3, and the operating voltage is Vp3.

  Since the operating voltage Vp1 of the solar battery 11 is in the intermediate voltage range (Va <Vp3 <Vb) between the rated voltages Va and Vb of the two secondary batteries, the second secondary battery selection unit 20 has two secondary batteries. A command is output to the maximum power follow-up control unit 23 so that the solar battery 11 is operated at the rated voltages Va and Vb of the batteries 12a and 12b, respectively. And the output electric power P3a and P3b when the solar cell 11 is drive | operated by rated voltage Va and Vb by the maximum electric power follow-up control part 23 are acquired, and the larger secondary battery 12a, 12b is selected. That is, the output power P3a at the operating point C3a at the rated voltage Va and the output power P3b at the operating point C3b at the rated voltage Vb are obtained. In FIG. 3, the output power P3a is larger than the output power P3b. The battery selection unit 20 selects the secondary battery 12a and notifies the secondary battery connection unit 22 of the selected secondary battery 12a.

  As a result, the solar cell 11 is operated at the rated voltage Va of the secondary battery 12a, the operating point at that time is C3a, and the output power P of the solar cell 11 is P3a. Since the output power P3a of the solar cell 11 is larger than the output power P3b at the operating point C3b at the rated voltage Vb of the other secondary battery 12b, the power generation capability of the solar cell 11 is maximized, The secondary battery 12a can also be operated.

  Thus, during the maximum power follow-up control of the solar battery 11, charge / discharge control of the secondary batteries 12a and 12b is necessary, and the operating voltage Vp of the solar battery 11 is equal to the rated voltages Va and Vb of the two secondary batteries. When the intermediate voltage range (Va <Vp <Vb), the maximum power follow-up control unit 23 is activated to obtain the output power P3a and P3b when the solar cell 11 is operated at the rated voltages Va and Vb. The secondary battery 12a, 12b is selected. Therefore, the secondary battery 12a, 12b connected to the solar cell 11 can be charged / discharged while maximizing the power generation capability of the solar cell 11.

  In the above description, when the operating voltage Vp of the solar cell 11 is in the intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries, the second secondary battery selection unit 20 23, the output power P3a and P3b when the solar cell 11 is operated at the rated voltages Va and Vb are acquired, and the larger secondary batteries 12a and 12b are selected. Instead of operating the solar cell 11 at the rated voltages Va and Vb of the secondary batteries 12a and 12b, the output voltage-output power characteristic (VP characteristic) of the solar battery 11 near the operating voltage of the solar battery 11 at that time ) And the secondary batteries 12a and 12b whose output power P increases when the operating voltage Vp of the solar battery 11 is set to the rated voltage of the two secondary batteries based on the approximate curve. You may be allowed to select

  FIG. 4 shows the case where the operating voltage Vp of the solar battery 11 of the photovoltaic power generator according to the first embodiment of the present invention is in the intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries. It is explanatory drawing in the case of selecting a secondary battery using the approximated curve of P characteristic.

  As shown in FIG. 4, when the solar cell 11 is operating at the operating point C31 and the operating voltage Vp of the solar cell 11 is in the intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries, The second secondary battery selection unit 20 receives the operating voltage Vp3 and the operating current Ip3 of the operating point C31 from the maximum power tracking control unit 23, and based on the operating voltage Vp3 and the operating current Ip3 of the operating point C31, the operating voltage Vp3. Approximate curves P3 ′ and P3 ″ of the VP characteristic curve P3 of the nearby solar cell 11 are calculated. The approximate curve P3 ′ is an approximate curve in a direction lower than the operating voltage Vp3 at the operating point C31, and the approximated curve P3 ″ is It is an approximate curve in a direction higher than the operating voltage Vp3 at the operating point C31.

  Generally, the VP characteristic curve P varies depending on the solar radiation intensity. When the solar radiation intensity is high, the VP characteristic curve P1 shown in FIG. 2A is obtained, and when the solar radiation intensity is low, the VP characteristic curve P2 shown in FIG. 2B is obtained. Further, when the solar radiation intensity is intermediate between FIGS. 2A and 2B, an intermediate VP characteristic curve P3 as shown in FIG. 4 is obtained. Since the operating point C31 of the VP characteristic curve P3 is the maximum output P3max, if the operating voltage Vp3 and the operating current Ip3 at the operating point C31 are known, the approximate curve P3 ′ in the direction lower than the operating voltage Vp3 in the vicinity of the operating point C31. The approximate curve P3 ″ in the direction higher than the operating voltage Vp3 in the vicinity of the operating point C31 can be easily obtained.

  And the output when the operating voltage Vp of the solar cell 11 is set to the rated voltages Va and Vb of the two secondary batteries from the approximate curves P3 ′ and P3 ″ of the VP characteristic curve P3 of the solar cell 11 near the voltage. The powers P3a ′ and P3b ″ are obtained, and the larger secondary battery 12a and 12b of the output powers P3a ′ and P3b ″ is selected. In the case of FIG. 4, the output power P3a ′ of the secondary battery 12a is large. The secondary battery selection unit 20 notifies the secondary battery connection unit 22 of the selected secondary battery 12a.

  As a result, the solar cell 11 is operated at the rated voltage Va of the secondary battery 12a, the operating point at that time is C3a, and the output power P of the solar cell 11 is P3a. Therefore, the secondary battery 12b can be operated while maximizing the power generation capability of the solar battery 11. In this case, the selection of the secondary batteries 12a and 12b is obtained by the approximate curves P3 ′ and P3 ″ without depending on the operation at the rated voltages Va and Vb of the secondary batteries 12a and 12b by the maximum power tracking control unit 23. This makes it possible to quickly determine which secondary battery 12a, 12b is selected.

  According to the first embodiment, during the maximum power follow-up control of the solar battery 11, charge / discharge control of the secondary batteries 12a and 12b is necessary, and the operating voltage Vp of the solar battery 11 is that of the two secondary batteries. When the intermediate voltage range between the rated voltages Va and Vb (Va <Vp <Vb) is not satisfied, the secondary batteries 12a and 12b having the rated voltages Va and Vb close to the operating voltage Vp of the solar battery 11 are selected and the operation of the solar battery 11 is performed. When the voltage Vp is in the intermediate voltage range (Va <Vp <Vb) between the rated voltages Va and Vb of the two secondary batteries, the maximum power follow-up control unit 23 is activated and the solar battery 11 is operated with the rated voltages Va and Vb. Output power P3a, P3b when the is operated is selected, and the larger secondary battery 12a, 12b is selected. Therefore, the secondary battery 12a, 12b connected to the solar cell 11 can be charged / discharged while maximizing the power generation capability of the solar cell 11.

  Further, when the operating voltage Vp of the solar battery 11 is in the intermediate voltage range (Va <Vp <Vb) between the rated voltages Va and Vb of the two secondary batteries, the secondary battery 12a by the maximum power tracking control unit 23, If the approximate curves P3 ′ and P3 ″ are obtained without using the rated voltages Va and Vb of 12b, the secondary batteries 12a and 12b can be selected quickly.

  Next, a second embodiment of the present invention will be described. FIG. 5 is a configuration diagram of a photovoltaic power generation apparatus according to the second embodiment of the present invention. In the second embodiment, an inverter output monitoring unit 27 is added to the first embodiment shown in FIG. 1, and the inverter output monitoring unit 27 is connected to the inverter during operation of the secondary battery 12. When the output power of 15 changes by a predetermined value or more, a command to disconnect the secondary battery 12 from the solar battery 11 is output to the secondary battery connection unit 22 and the solar cell operating voltage determination unit 18 is activated. Is. When activated, the solar cell operating voltage determination unit 18 determines whether or not the operating voltage Vp of the solar cell 11 is in the intermediate voltage range (Va <Vp <Vb), and the first secondary battery selection unit 19 or the second secondary battery selection unit 20 searches for the secondary batteries 12a and 12b having a larger output power. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  Now, it is assumed that the secondary battery 12b is connected in parallel to the solar battery 11 and is operated at the operating point C1b of the rated voltage Vb of the secondary battery 12b of the VI characteristic curve C1, as shown in FIG. The output power P of the solar cell 11 in this case is P1b determined by the VP characteristic curve P1. The operating point C11 is the optimum operating point for the maximum output P1max at which the output power of the solar cell 11 is maximized.

  In this state, if the sunshine intensity is changed and the VI characteristic curve C1 is changed to the VI characteristic curve C2, the operating point of the solar cell 11 is changed from the operating point C1b of the VI characteristic curve C2 to VI. The operating point C2b of the characteristic curve C2 is changed. Therefore, the output power P of the solar cell 11 changes from P1b determined by the VP characteristic curve P1 to P2b determined by the VP characteristic curve P2.

  The inverter output monitoring unit 27 monitors the change ΔP (= P1b−P2b) of the output power P, and when the change ΔP of the output power P exceeds a predetermined value, a command to disconnect the secondary battery 12b from the solar battery 11. Is output to the secondary battery connection unit 22 and the solar cell operating voltage determination unit 18 of the secondary battery selection unit 17 is activated.

  When the secondary battery 12b is disconnected from the DC system 14 by the secondary battery connection unit 22, the maximum power tracking control unit 23 performs maximum power tracking control, and the operating point of the solar cell 11 is the VI characteristic curve C2. The operating point C2b changes to the operating point C22 of the VI characteristic curve C2. Therefore, the output power P of the solar cell 11 changes from P2b determined by the VP characteristic curve P2 to P2max determined by the VP characteristic curve P2.

  The solar cell operating voltage determination unit 18 determines whether or not the operating voltage Vp (= Vp2) in the changed VI characteristic curve C2 is in the intermediate voltage range (Va <Vp <Vb), and the first secondary battery The selection unit 19 or the second secondary battery selection unit 20 searches for the secondary batteries 12a and 12b having a larger output power.

  This is because when the output power P of the solar battery 11 changes by a predetermined value or more, the operating point C2b is determined by the changed VI characteristic curve C2 according to the rated voltage Vb of the currently connected secondary battery 12b. This is because the output power P2b is not always close to the maximum output P2max determined by the changed VI characteristic curve C2.

  FIG. 6 shows a case where the operating voltage Vp (= Vp2) of the solar cell 11 is not in the intermediate voltage range (Va <Vp <Vb). Since the operating voltage Vp (= Vp2) of the solar cell 11 is not in the intermediate voltage range (Va <Vp <Vb), the operating point at which the output power P of the solar cell 11 becomes the maximum output P2max with the changed VI characteristic curve C2. The secondary battery 12 having a rated voltage close to the operating voltage Vp2 at C22 is searched again.

  On the other hand, when the operating voltage Vp of the solar battery 11 is in the intermediate voltage range (Va <Vp <Vb), the secondary battery selection unit 17 performs the processing shown in FIG. 3 or FIG. 4 of the first embodiment. Therefore, the secondary battery 12 having a large output power is searched again.

  According to the second embodiment, when the output power P of the inverter 15 changes more than a predetermined value during the operation of the secondary battery 12, it is estimated that the operating voltage Vp of the maximum output of the solar battery 11 has changed. The secondary battery 12 that is currently connected is disconnected from the solar battery 11, the secondary battery 12a, 12b is searched again, and the output power P of the solar battery 11 can be operated near the maximum output. Therefore, even when the operating voltage V of the maximum output of the solar cell 11 changes, the solar cell 11 can be operated near the maximum output in accordance with the fluctuation of the output power of the solar cell 11.

  Next, a third embodiment of the present invention will be described. FIG. 7 is a configuration diagram of a photovoltaic power generation apparatus according to the third embodiment of the present invention. In the third embodiment, a charging depth monitoring unit 28 is additionally provided to the first embodiment shown in FIG. 1, and the charging depth monitoring unit 28 includes two secondary batteries 12a and 12b. When the charge depth of the battery deviates from the predetermined range, a connection switching command is output to the secondary battery connection unit 22 so that the charge depths of the two secondary batteries 12a and 12b are equalized, and requested from the charge / discharge control unit. When there is, a charge / discharge command for making the charging depth of the two secondary batteries 12a, 12b uniform is output. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  The charging depth monitoring unit 28 inputs the charging depths ca and cb of the secondary batteries 12a and 12b, and the charging depths ca and cb of the secondary batteries 12a and 12b deviate from a predetermined range (for example, 20% to 80%). Determine whether or not. When the charging depths ca and cb of the secondary batteries 12a and 12b deviate from a predetermined range (20% to 80%), a connection switching command is output to the secondary battery connection unit 22. For example, when the charged amount of the secondary battery 12a is 90%, a connection switching command for discharging is output, and when the charged amount of the secondary battery 12b is 10%, a connection switching command for charging is output. To do.

  When the secondary battery connection unit 22 inputs the connection switching command from the charge depth monitoring unit 28, the secondary battery connection unit 22 stores the connection switching command. Then, the secondary battery connection unit 22 waits for selection information of the secondary batteries 12a and 12b from the first secondary battery selection unit 19 or the second secondary battery selection unit 20, and waits for the first secondary battery selection unit 19 or The secondary batteries 12 a and 12 b selected by the second secondary battery selection unit 20 are connected in parallel to the solar battery 11 of the DC system 14.

  Now, the storage amount of the secondary battery 12a is 90%, and the storage amount of the secondary battery 12b is 10%, and is selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20. Assume that the secondary battery is the secondary battery 12a. In this case, since the storage amount of the secondary battery 12a is 90%, the connection switching command from the charge depth monitoring unit 28 is a connection switching command for discharging. Therefore, the secondary battery connection unit 22 outputs a command to turn on the switching element 26a2 of the switch circuit 13a. Thereby, the secondary battery 12a can be operated only with respect to the discharge command.

  On the other hand, when the secondary battery selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20 is the secondary battery 12b, the storage amount of the secondary battery 12b is 10%. Thus, the connection switching command from the charge depth monitoring unit 28 is a connection switching command for charging. Therefore, the secondary battery connection unit 22 outputs a command to turn on the switching element 26b1 of the switch circuit 13b. Thereby, the secondary battery 12b can be operated only with respect to the charge command.

  The charge / discharge control unit 24 determines whether or not the external charge / discharge command S matches the charge / discharge by the connection switching from the secondary battery connection unit 22. When the charge / discharge coincides, charge / discharge control is performed on the secondary batteries 12a, 12b in accordance with an external charge / discharge command.

  On the other hand, when the charge / discharge command S from the outside does not coincide with charge / discharge by connection switching from the secondary battery connection unit 22, the charge / discharge control unit 24 supplies two secondary batteries to the charge depth monitoring unit 28. A charge / discharge command for equalizing the charging depth of 12a and 12b is requested. When the charge depth monitoring unit 28 receives a charge / discharge command request from the charge / discharge control unit 24, the charge depth monitoring unit 28 outputs a charge / discharge command that matches the connection command to the secondary battery connection unit 22. As a result, the charge / discharge control unit 24 performs charge / discharge control on the secondary batteries 12a and 12b with the charge / discharge command from the charge depth monitoring unit 28 instead of the charge / discharge command S from the outside. In other words, charge / discharge control is performed with priority given to uniform charge depth of the two secondary batteries 12a and 12b.

  The charge / discharge command from the charge depth monitoring unit 28 is, for example, a discharge command in which the storage amount of the secondary battery 12a is 50% of the reference value when the storage amount of the secondary battery 12a is 90%. If it is 10%, the charging command is 50% of the reference value. The charge / discharge control unit 24 performs charge / discharge based on the charge / discharge command from the charge depth monitoring unit 28. As a result, when the charge depth of the two secondary batteries 12a, 12b becomes uniform, the external charge / discharge command S Follow the instructions.

  According to the third embodiment, when the charging depths of the two secondary batteries 12a and 12b are detected and the charging depths of the two secondary batteries 12a and 12b are out of the predetermined range, the charging depth is determined. Charge / discharge control is performed so that becomes the reference value, the charging depth of each of the secondary batteries 12a and 12b is made uniform.

  FIG. 8 is a configuration diagram of a photovoltaic power generation apparatus according to the fourth embodiment of the present invention. In the fourth embodiment, one of the two secondary batteries 12a and 12b is connected during the maximum power follow-up control of the solar cell 11 with respect to the first embodiment shown in FIG. Instead, one of the two secondary batteries 12a and 12b is connected when the solar battery 11 is started. Also in this case, the secondary battery selection unit 17 selects the secondary batteries 12a and 12b whose output power from the solar battery 11 is increased. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  The secondary battery selection unit 17 is configured to be able to select the secondary batteries 12a and 12b whose output power from the solar battery 11 is increased when the solar battery 11 is started. That is, the secondary battery selection unit 17 includes a solar cell activation unit 29, an output power increase direction determination unit 30, a provisional selection unit 31, a solar cell output power determination unit 32, and a final selection unit 33. Yes.

  When a start command for the solar battery 11 is input, the solar battery starter 29 of the secondary battery selector 17 starts the maximum power follow-up controller 23 and the rated voltages Va of the two secondary batteries 12a and 12b, Maximum power follow-up control is started in the intermediate voltage range of Vb.

  The output power increase direction determination unit 30 of the secondary battery selection unit 17 determines the voltage direction in which the output power of the solar cell 11 is increased by the maximum power tracking control of the maximum power tracking control unit 23 activated by the solar cell activation unit 29. judge. Since the maximum power follow-up control unit 23 starts the maximum power follow-up control in the intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries 12a and 12b, the output power of the solar cell 11 is the maximum power follow-up control. It is not necessarily the maximum power at the start. Therefore, when the maximum power tracking control unit 23 starts the maximum power tracking control and changes the operating voltage, there is a voltage direction in which the output power increases. The output power increase direction determination unit 30 detects the voltage direction in which the output power at that time increases, and detects the increased output power of the solar cell 11.

  The provisional selection unit 31 of the secondary battery selection unit 17 tentatively selects the secondary battery 12 having the rated voltage in the voltage direction determined by the output power increase direction determination unit 30 and supplies the secondary battery connection unit 22 with the secondary battery 12. Information on the selected secondary battery 12 is notified.

  When the secondary battery connection unit 22 receives the notification of the secondary battery 12 selected by the temporary selection unit 31, the secondary battery connection unit 22 determines whether the external charge / discharge command S is a charge command or a discharge command, and the switch circuit 13 according to the charge / discharge command. The switching element 26 connects the secondary battery 12 to the solar battery 11 of the DC system 14 in parallel. For example, when the secondary battery 12 selected by the provisional selection unit 31 is the secondary battery 12b and the charge / discharge command is the discharge command, the secondary battery connection unit 22 sets the switching element 26b2 of the switch circuit 13b. The secondary battery 12b is turned on and connected to the solar battery 11 of the DC system 14 in parallel.

  In the following description, the case where the secondary battery 12 selected by the provisional selection unit 31 is the secondary battery 12b and the charge / discharge command S from the outside is a discharge command will be described.

  The secondary battery connection unit 22 notifies the charge / discharge control unit 24 that the secondary battery 12b selected by the provisional selection unit 31 is connected to the DC system 14. Thereby, the charge / discharge control part 24 outputs the discharge command according to the charge / discharge command S from the outside to the inverter control part 25, and performs discharge control.

  Next, the solar cell output power determination unit 32 inputs the output power of the solar cell 11 at the rated voltage Vb of the secondary battery 12b selected by the temporary selection unit 31 from the maximum power follow-up control unit 23, and the output power The output power of the solar cell 11 when the voltage direction in which the output power increases is detected from the increase direction determination unit 30 is input.

  Since the solar battery 11 is operated at the rated voltage Vb of the secondary battery 12b when the secondary battery 12b is connected in parallel, the solar battery output power determination unit 32 is operated at the rated voltage Vb of the secondary battery 12b. The output power of the solar cell 11 is input, and it is determined whether or not the output power is larger than the output power as determined by the output power increase direction determination unit 30. Then, the determination result is output to the final selection unit 33.

  The final selection unit 33 determines that the output power of the solar cell 11 at the rated voltage Vb of the secondary battery 12b selected by the temporary selection unit 31 is the output power increase direction determination unit 30 based on the determination result of the solar cell output power determination unit 32. If it is determined that the output power is greater than that determined in step (b), the secondary battery 12b is selected. Since the secondary battery 12b is already connected in parallel to the solar battery 11 of the DC system 14, it is left as it is. In this case, the operation at the rated voltage of the secondary battery 12 for selecting the secondary battery 12 is sufficient.

  On the other hand, when the output power of the solar cell 11 at the rated voltage Vb of the secondary battery 12b selected by the temporary selection unit 31 is determined by the output power increase direction determination unit 30 based on the determination result of the solar cell output power determination unit 32 When it is determined that the output power is smaller than the secondary battery 12b, the final selection unit 33 connects the secondary battery 12a in parallel to the solar battery 11 of the DC system 14 in place of the secondary battery 12b. A command is output to the unit 22.

  As a result, the secondary battery connection unit 22 turns off the switching element 26b2 of the switch circuit 13b, and turns on the switching element 26a2 of the switch circuit 13a because the external charge / discharge command S is a discharge command. In this way, the other secondary battery 12 a is connected in parallel to the solar battery 11 of the DC system 14. When the secondary battery 12a is connected in parallel to the solar battery 11 of the DC system 14, the operating voltage of the solar battery 11 becomes the rated voltage Va of the secondary battery 12a. Therefore, the output power of the solar battery 11 is the secondary battery. The output power at the rated voltage Va of 12a is obtained.

  The final selection unit 33 outputs the output power of the solar cell 11 at the rated voltage Vb of the secondary battery 12b selected by the provisional selection unit 31, and the output power of the solar cell 11 at the rated voltage Va of the other secondary battery 12a. And the secondary battery 12 with the larger output power is selected. When the selected secondary battery 12 is the secondary battery 12a, the secondary battery 12a is in a state of being connected in parallel to the solar battery 11 of the DC system 14, and is left as it is. On the other hand, when the selected secondary battery 12 is the secondary battery 12b, a connection switching command to the secondary battery 12b is output to the secondary battery connection unit 22. Thereby, it replaces with the secondary battery 12a and the secondary battery 12b is connected in parallel with the solar cell 11 of the DC system 14. In this case, the operation at the rated voltage of the secondary battery 12 for selecting the secondary battery 12 is required twice, but the secondary battery 12 with the larger output power of the solar battery 11 can always be selected.

  FIG. 9 is a graph of the VI characteristics and VP characteristics of a solar cell showing an example of the operation of the photovoltaic power generation apparatus according to the fourth embodiment of the present invention. FIG. 9 shows a VI characteristic curve C1 and a VP characteristic curve P1 using the solar radiation intensity when the temperature of the solar cell 11 is constant as a parameter, and a secondary for selecting the secondary battery 12 is shown. The case where the operation | movement by the rated voltage of the battery 12 only needs once is shown.

  When the solar cell 11 is activated, the maximum power tracking control unit 23 is activated. As shown in FIG. 9, the operating voltage Vp1 of the solar cell 11 is an intermediate voltage between the rated voltages Va and Vb of the two secondary batteries 12a and 12b. Maximum power tracking control is started in the range. The output power of the solar cell 11 at this time is P1p. Since the output power of the solar battery 11 is not necessarily the maximum output power at the start of the maximum power tracking control, there is a voltage direction in which the output power increases.

  FIG. 9 shows a case where the operating voltage Vp1 'is moved in the positive direction by a minute voltage ΔV to obtain the operating voltage Vp1'. In the operating voltage Vp1 ′ in which the operating voltage Vp1 is changed by ΔV in the positive direction by this maximum power tracking control, the output power of the solar cell 11 is P1p ′, and P1p ′> P1p. Therefore, the operating voltage Vp1 is set in the positive direction. When moved, it turns out that the output electric power of the solar cell 11 is increasing. The output power increase direction determination unit 30 detects the voltage direction (positive direction) in which the output power increases and also detects the increased output power P1p ′ of the solar cell 11.

  Next, the provisional selection unit 31 provisionally selects the secondary battery 12b having the rated voltage Vb in the voltage direction (positive direction) determined by the output power increase direction determination unit 30. Then, the secondary battery 12b is connected in parallel to the solar battery 11 of the DC system 14, and the solar battery output power determination unit 32 obtains the output power P1b of the solar battery 11 at the rated voltage Vb of the secondary battery 12b. It is determined whether or not the output power P1p ′ increased at the start of the maximum power tracking control. In FIG. 9, P1b> P1p ′.

  The final selection unit 33 selects the secondary battery 12b because the output power P1b of the solar battery 11 at the rated voltage Vb of the secondary battery 12b is greater than the increased output power P1p ′ at the start of the maximum power tracking control. . Since the secondary battery 12b is already connected in parallel to the solar battery 11 of the DC system 14, it is left as it is. In this case, since the maximum power follow-up control unit 23 is operated only at the rated voltage Vb of the secondary battery 12b, it can be seen that the secondary battery 12b is the desired secondary battery. The secondary battery 12 can be operated at the rated voltage only once.

  FIG. 10 is a graph of the VI characteristics and VP characteristics of a solar cell showing another example of the operation of the photovoltaic power generation apparatus according to the fourth embodiment of the present invention. FIG. 10 shows a VI characteristic curve C2 and a VP characteristic curve P2 using the solar radiation intensity when the temperature of the solar cell 11 is constant as a parameter, and a secondary for selecting the secondary battery 12 is shown. The case where the operation | movement with the rated voltage of the battery 12 is required twice is shown.

  As in the case of FIG. 9, at the time of starting the solar cell 11, the maximum power follow-up control is started in the intermediate voltage range Vp2 between the rated voltages Va and Vb of the two secondary batteries 12a and 12b. The output power of the solar cell 11 at this time is P2p.

  Similarly to the case of FIG. 9, when the operating voltage Vp2 is moved in the positive direction by a minute voltage ΔV to be the operating voltage Vp2 ′, the output power of the solar cell 11 is P2p ′, and Vp2 ′> Vp2. It can be seen that when the operating voltage Vp2 is moved in the positive direction, the output power of the solar cell 11 is increased. The output power increase direction determination unit 30 detects the voltage direction (positive direction) in which the output power increases, and detects the increased output power P2p ′ of the solar cell 11.

  Next, the provisional selection unit 31 provisionally selects the secondary battery 12b having the rated voltage Vb in the voltage direction (positive direction) determined by the output power increase direction determination unit 30. Then, the secondary battery 12b is connected in parallel to the solar battery 11 of the DC system 14, and the solar battery output power determination unit 32 obtains the output power P2b of the solar battery 11 at the rated voltage Vb of the secondary battery 12b. It is determined whether or not the output power P2p ′ increased at the start of the maximum power follow-up control. In FIG. 10, P2b <P2p ′.

  Since the output power P2b of the solar cell 11 at the rated voltage Vb of the secondary battery 12b is smaller than the increased output power P2p ′ at the start of the maximum power tracking control, the final selection unit 33 replaces the secondary battery 12b with the other Are connected in parallel to the solar cell 11 of the DC system 14. When the secondary battery 12a is connected in parallel to the solar battery 11 of the DC system 14, the operating voltage of the solar battery 11 becomes the rated voltage Va of the secondary battery 12a. Therefore, the output power P2a of the solar battery 11 is the secondary voltage. It becomes the output power at the rated voltage Va of the battery 12a.

  The final selection unit 33 outputs the output power P2b of the solar cell 11 at the rated voltage Vb of the secondary battery 12b selected by the provisional selection unit 31, and the output of the solar cell 11 at the rated voltage Va of the other secondary battery 12a. The power P2a is compared. In the case of FIG. 10, since P2a> P2b, the final selection unit 33 selects the secondary battery 12a with the larger output power P2a. Since the selected secondary battery 12a is connected in parallel to the solar battery 11 of the DC system 14, it is left as it is.

  When P2a <P2b, the secondary battery 12b is selected. In that case, the selected secondary battery 12 connects the secondary battery 12b in parallel to the solar battery 11 of the DC system 14 instead of the secondary battery 12a.

  Thus, the output power P2b of the solar cell 11 at the rated voltage Vb of the secondary battery 12b selected by the provisional selection unit 31 is the output power P2a of the solar cell 11 at the rated voltage Va of the other secondary battery 12a. If it is smaller, the operation at the rated voltage of the secondary battery 12 for selecting the secondary battery 12 is required twice, but the secondary battery 12 with the larger output power of the solar battery 11 is always selected. it can.

  In 4th Embodiment, when connecting either of the secondary batteries 12a and 12b at the time of starting of the solar cell 11, the maximum power follow-up control unit 23 is started and the two secondary batteries 12a and 12b are connected. The maximum power follow-up control is started in the intermediate voltage range of the rated voltages Va and Vb, and the secondary battery 12 having the rated voltage in the voltage direction in which the output power of the solar battery 11 is increased by the maximum power follow-up control is temporarily selected. Then, it is determined whether or not the output power of the solar battery 11 at the rated voltage of the secondary battery 12 is larger than the output power when the voltage direction is determined. When the output power is large, the secondary battery 12 is selected. Therefore, the operation at the rated voltage of the secondary battery 12 for selecting the secondary battery 12 is only required once, and the secondary battery 12 to be connected can be quickly determined.

  On the other hand, when the output power of the solar battery 11 at the rated voltage of the temporarily selected secondary battery 12 is smaller than the output power when the voltage direction is determined, the solar battery at the rated voltage of the other secondary battery 12 11 output power. Then, the secondary battery with the larger output power is selected. Therefore, in this case, the operation at the rated voltage of the secondary battery for selecting the secondary battery 12 is performed twice, but the secondary battery with the higher output power of the solar battery 11 can always be selected.

  In the above description, the case where the two secondary batteries 12a and 12b are connected to the solar battery 11 has been described, but three or more secondary batteries 12a to 12n are connected, and any of the secondary batteries 12a to 12n is connected. When such charge / discharge control becomes necessary, any of the secondary batteries 12 can be selected and connected.

  FIG. 11 is a configuration diagram of a photovoltaic power generation apparatus according to the fifth embodiment of the present invention. The fifth embodiment shows a case where three secondary batteries 12 a, 12 b and 12 c are connected to the solar battery 11 as a plurality of secondary batteries 12. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 11, three secondary batteries 12a, 12b, and 12c are connected in parallel to the solar battery 11 via switch circuits 13a, 13b, and 13c, and a DC system 14 is formed. The switch circuits 13a, 13b, and 13c have charging switching elements 26a1, 26b1, and 26c1 and discharging switching elements 26a2, 26b2, and 26c2, and the secondary battery connection unit 22 is connected to the secondary batteries 12a, 12b, and 12c. When charging, the switching elements 26a1, 26b1, 26c1 are turned on. When discharging from the secondary batteries 12a, 12b, 12c, the switching elements 26a2, 26b2, 26c2 are turned on, and the secondary batteries 12a, 12b, 12c are turned on DC. Connect to system 14.

  FIG. 12 shows an intermediate voltage between the rated voltages Va, Vb, and Vc of the three secondary batteries 12a, 12b, and 12c as the operating voltage Vp of the solar battery 11 of the photovoltaic power generation apparatus according to the fifth embodiment of the present invention. FIG. 12A is a graph showing an example of the VI characteristic and the VP characteristic of the solar cell 11 when not in the range, and FIG. 12A shows the operating voltage Vp of the solar cell 11 and three secondary batteries having high solar radiation intensity. The graph which shows an example of VI characteristic curve C1 and VP characteristic curve P1 in case the relationship with rated voltage Va, Vb, Vc of 12a, 12b, 12c is (Vp> Va, Vb, Vc), 12 (b) has a low solar radiation intensity, and the relationship between the operating voltage Vp of the solar cell 11 and the rated voltages Va, Vb, Vc of the three secondary batteries 12a, 12b, 12c (Vp <Va, Vb, Vc). VI characteristic curve C2 and VP characteristics Is a graph showing an example of a curve P2. FIG. 12 shows a VI characteristic curve and a VP characteristic curve using the solar radiation intensity when the temperature of the solar cell 11 is constant as a parameter.

  Here, the intermediate voltage range is a voltage range in which the operating voltage Vp of the solar battery 11 is not less than the minimum value and not more than the maximum value among the rated voltages Va to Vn of the secondary batteries 12 to 12n having three or more. I will say. Therefore, when there are three secondary batteries 12, a voltage range that is greater than or equal to the minimum value and less than the maximum value of the rated voltages Va, Vb, and Vc of the three secondary batteries 12a, 12b, and 12c is set to the intermediate voltage. It will be a range.

  As shown in FIG. 12 (a), when the solar radiation intensity is high, this is the optimum operating point at which the output power becomes maximum at the coordinate C11 on the VI characteristic curve C1, and the solar cell 11 follows the maximum power. The controller 23 is operating at the operating point C11, and the output power at that time is the maximum power P1max of the VP characteristic curve P1, and the operating voltage is Vp1.

  The operating voltage Vp1 of the solar battery 11 is the rated voltages Va, Vb, and Vc of the three secondary batteries 12a, 12b, and 12c (Va <Vb <Vc), and the operating voltage Vp1 of the solar battery 11 is the secondary battery 12c. When the voltage is larger than the rated voltage Vc and not in the intermediate voltage range (Va <Vp1 <Vc), the first secondary battery selection unit 19 uses the secondary battery 12c with the rated voltage Vc closest to the operating voltage Vp1 of the solar battery 11. Is selected, and the selected secondary battery 12 c is notified to the secondary battery connection unit 22.

  Thereby, the solar cell 11 will be drive | operated with the rated voltage Vc of the secondary battery 12c, the operating point at that time will be C1c, and the output electric power P of the solar cell 11 will be P1c. The output power P1c of the solar cell 11 is larger than the output powers P1a and P1b at the operating points C1a and C1b at the rated voltages Va and Vb of the remaining secondary batteries 12a and 12b. Therefore, the secondary battery 12c can be operated while maximizing the power generation capability of the solar battery 11.

  Next, as shown in FIG. 12B, when the solar radiation intensity is small, the output power is the optimum operating point at the coordinate C21 on the VI characteristic curve C1, and the solar cell 11 is The maximum power follow-up control unit 23 is operating at the operating point C21, the output power at that time is the maximum power P2max of the VP characteristic curve P2, and the operating voltage is Vp2.

  Since the operating voltage Vp2 of the solar cell 11 is not an intermediate voltage range (Va <Vp2 <Vc) of the rated voltages Va, Vb, and Vc of the three secondary batteries, the first secondary battery selection unit 19 The secondary battery 12a having the rated voltage Va closest to the operating voltage Vp2 is selected, and the selected secondary battery 12a is notified to the secondary battery connection unit 22.

  Thus, the solar cell 11 is operated at the rated voltage Va of the secondary battery 12a, the operating point at that time is C2a, and the output power P of the solar cell 11 is P2a. The output power P2a of the solar cell 11 is larger than the output powers P2b and P2c at the operating points C2b and C2c when the remaining secondary batteries 12b and 12c are at the rated voltages Vb and Vc. Therefore, the secondary battery 12a can be operated while maximizing the power generation capability of the solar battery 11.

  Thus, during the maximum power tracking control of the solar cell 11, charge / discharge control is required for any of the three secondary batteries 12a, 12b, and 12c, and the operating voltage Vp of the solar cell 11 is three secondary. When the rated voltage Va, Vb, Vc of the batteries 12a, 12b, 12c is not in the intermediate voltage range (Va <Vp <Vc), the secondary battery 12 having a rated voltage close to the operating voltage Vp of the solar battery 11 is selected. The secondary batteries 12a, 12b, and 12c connected to the solar battery 11 can be charged / discharged while maximizing the power generation capacity of the solar battery 11. That is, it is possible to easily determine which secondary battery 12a, 12b, or 12c is selected.

  FIG. 13 shows an intermediate voltage between the rated voltages Va, Vb, and Vc of the three secondary batteries 12a, 12b, and 12c as the operating voltage Vp of the solar battery 11 of the photovoltaic power generation apparatus according to the fifth embodiment of the present invention. It is a graph which shows an example of the VI characteristic and VP characteristic of the solar cell 11 when it is the range (Va <Vp <Vb of rated voltage Va <Vp <Vc). FIG. 13 shows a VI characteristic curve and a VP characteristic curve using the solar radiation intensity when the temperature of the solar cell 11 is constant as parameters, and the solar radiation intensity is shown in FIGS. 12 (a) and 12 (b). ) In the middle.

  As shown in FIG. 13, it is the optimum operating point at which the output power becomes maximum at the coordinate C31 on the VI characteristic curve C3, and the solar battery 11 is operated at the operating point C31 by the maximum power tracking control unit 23. The output power at that time is the maximum power P3max of the VP characteristic curve P3, and the operating voltage is Vp3.

  The second secondary battery selection unit 20 is configured such that the operating voltage Vp3 of the solar battery 11 is between the rated voltages Va and Vb of the secondary batteries 12a and 12b in the intermediate voltage range (Va <Vp <Vc). 11 is within the operating voltage range sandwiched between the rated voltages Va and Vb of the secondary batteries 12a and 12b. Therefore, the solar battery 11 has the rated voltages Va and Vb of the two secondary batteries 12a and 12b, respectively. A command is output to the maximum power follow-up control unit 23 so as to operate.

  And the output power P3a, P3b when the solar cell 11 is drive | operated by rated voltage Va, Vb by the maximum electric power tracking control part 23 is acquired, and the larger secondary battery 12a, 12b is selected temporarily. In the case of FIG. 13, since the output power P3b of the secondary battery 12b is larger than the output power P3a of the secondary battery 12a, the second secondary battery selection unit 20 temporarily selects the secondary battery 12b. Then, the output power P of the solar battery 11 at the rated voltage of the secondary battery 12 outside the operating voltage range of the rated voltage Vb of the temporarily selected secondary battery 12b is obtained, and the temporarily selected secondary battery is obtained. The secondary battery 12 including the battery 12b and having the maximum output power P of the solar battery 11 is selected.

  That is, the output power P3a at the operating point C3a at the rated voltage Va and the output power P3b at the operating point C3b at the rated voltage Vb are acquired. In FIG. 13, the output power P3b is larger than the output power P3a. The battery selection unit 20 temporarily selects the secondary battery 12b, and further, the solar at the rated voltage Vc of the secondary battery 12c outside the operating voltage range of the rated voltage Vb of the temporarily selected secondary battery 12b. The output power P3c of the battery 11 is obtained, and the secondary battery 12b having the maximum output power P of the solar battery 11 including the temporarily selected secondary battery 12b is selected. The secondary battery connection unit 22 is notified of the selected secondary battery 12b.

  Thus, the solar cell 11 is operated at the rated voltage Vb of the secondary battery 12b, the operating point at that time is C3b, and the output power P of the solar cell 11 is P3b. Since the output power P3b of the solar battery 11 is larger than the output power P3a and P3c at the operating points C3a and C3c at the rated voltages Va and Vc of the remaining secondary batteries 12a and 12c, the power generation capacity of the solar battery 11 is increased. The secondary battery 12b can also be operated while maximizing it.

  Thus, during the maximum power follow-up control of the solar battery 11, charge / discharge control of the secondary batteries 12a, 12b, and 12c is required, and the operating voltage Vp of the solar battery 11 is the rated voltage Va of the three secondary batteries, When the intermediate voltage range between Vb and Vc (Va <Vp <Vc), the second secondary battery selection unit 20 determines whether the operating voltage Vp of the solar cell 11 is within the intermediate voltage range (Va <Vp <Vc). It is determined which of the two rated voltages is sandwiched between the operating voltage ranges, and the maximum power follow-up control unit 23 uses the rated voltages of the two secondary batteries 12 that form the operating voltage range, respectively. 11 is operated, the secondary battery with the larger output power at that time is temporarily selected, and the rating of the secondary battery 12 outside the operating voltage range of the rated voltage of the temporarily selected secondary battery 12 Obtaining the output power P of the solar cell 11 in terms of voltage , The output power P of the solar cell 11 selects the secondary battery 12 with the maximum output, including temporarily selected secondary batteries 12. Therefore, the secondary batteries 12a, 12b, and 12c connected to the solar battery 11 can be charged / discharged while maximizing the power generation capability of the solar battery 11.

  In the above description, the second secondary battery selection unit 20 operates such that the operating voltage Vp of the solar battery 11 is sandwiched between the rated voltages of the two secondary batteries 12 within the intermediate voltage range (Va <Vp <Vc). In the voltage range, the solar cell 11 is operated at the rated voltage of the two secondary batteries 12 that form the operating voltage range sandwiching the operating voltage Vp of the solar cell 11. An approximate curve of the output voltage-output power characteristic (VP characteristic) of the solar cell 11 in the vicinity of the operating voltage Vp of the solar cell 11 is calculated, and the secondary battery 12 having a large output power P is calculated based on the approximate curve. You may make it select.

  FIG. 14 shows the operation of the two secondary batteries 12a and 12b within the intermediate voltage range (Va <Vp <Vc) of the operating voltage Vp of the solar battery 11 of the photovoltaic power generator according to the fifth embodiment of the present invention. It is explanatory drawing at the time of selecting a secondary battery using the approximated curve of VP characteristic in the operating voltage range pinched | interposed between rated voltage Va and Vb.

  As shown in FIG. 14, when the solar cell 11 is operating at the operating point C31 and the operating voltage Vp of the solar cell 11 is in the intermediate voltage range between the rated voltages Va and Vb of the two secondary batteries, The second secondary battery selection unit 20 receives the operating voltage Vp3 and the operating current Ip3 of the operating point C31 from the maximum power tracking control unit 23, and based on the operating voltage Vp3 and the operating current Ip3 of the operating point C31, the operating voltage Vp3. Approximate curves P3 ′ and P3 ″ of the VP characteristic curve P3 of the nearby solar cell 11 are calculated. The approximate curve P3 ′ is an approximate curve in a direction lower than the operating voltage Vp3 at the operating point C31, and the approximated curve P3 ″ is It is an approximate curve in a direction higher than the operating voltage Vp3 at the operating point C31.

  Generally, the VP characteristic curve P varies depending on the solar radiation intensity. When the solar radiation intensity is high, a VP characteristic curve P1 shown in FIG. 12A is obtained, and when the solar radiation intensity is low, a VP characteristic curve P2 shown in FIG. 12B is obtained. Further, when the solar radiation intensity is intermediate between FIGS. 12A and 12B, an intermediate VP characteristic curve P3 as shown in FIG. 14 is obtained. Since the operating point C31 of the VP characteristic curve P3 is the maximum output P3max, if the operating voltage Vp3 and the operating current Ip3 at the operating point C31 are known, the approximate curve P3 ′ in the direction lower than the operating voltage Vp3 in the vicinity of the operating point C31. The approximate curve P3 ″ in the direction higher than the operating voltage Vp3 in the vicinity of the operating point C31 can be easily obtained.

  And the output when the operating voltage Vp of the solar cell 11 is set to the rated voltages Va and Vb of the two secondary batteries from the approximate curves P3 ′ and P3 ″ of the VP characteristic curve P3 of the solar cell 11 near the voltage. The powers P3a ′ and P3b ″ are obtained, and the larger secondary batteries 12a and 12b among the output powers P3a ′ and P3b ″ are temporarily selected.

  In the case of FIG. 14, since the output power P3b ″ of the secondary battery 12b is large, the secondary battery 12b is temporarily selected. Then, the operating voltage range of the rated voltage Vb of the temporarily selected secondary battery 12b. The output power P3c "of the solar battery 11 at the rated voltage Vc of the secondary battery 12c outside the center is obtained, and the output power P of the solar battery 11 including the secondary battery 12b temporarily selected becomes the maximum output. Next battery 12 is selected. In FIG. 14, since P3b ″> P3c ″, the second secondary battery selection unit 20 selects the secondary battery 12b and notifies the secondary battery connection unit 22 of the selected secondary battery 12b.

  Thus, the solar cell 11 is operated at the rated voltage Vb of the secondary battery 12b, the operating point at that time is C3b, and the output power P of the solar cell 11 is P3b. Therefore, the secondary battery 12b can be operated while maximizing the power generation capability of the solar battery 11. In this case, the selection of the secondary batteries 12a and 12b is obtained by the approximate curves P3 ′ and P3 ″ without depending on the operation at the rated voltages Va and Vb of the secondary batteries 12a and 12b by the maximum power tracking control unit 23. This makes it possible to quickly determine which secondary battery 12a, 12b is selected.

  According to the fifth embodiment, during the maximum power follow-up control of the solar battery 11, charge / discharge control of the secondary batteries 12a, 12b, and 12c connected to the solar battery 11 is required, and the operating voltage of the solar battery 11 is increased. When Vp is not in the intermediate voltage range (Va <Vp <Vc), the secondary battery 12 having a rated voltage close to the operating voltage Vp of the solar cell 11 is selected, and the operating voltage Vp of the solar cell 11 is in the intermediate voltage range (Va <V When the operating voltage range is sandwiched between the rated voltages of the two secondary batteries 12 within Vp <Vc), the two secondary batteries 12 that activate the maximum power follow-up control unit 23 to form the operating voltage range. The output power P when the solar cell 11 is operated at a rated voltage of 10 is temporarily selected, and the rated voltage of the secondary battery 12 outside the operating voltage range of the rated voltage of the secondary battery 12 temporarily selected is selected. The output power P of the solar cell 11 at The output power P of the solar cell 11 selects the secondary battery 12 with the maximum output, including temporarily selected secondary batteries 12. Therefore, the secondary battery 12a, 12b, 12c connected to the solar cell 11 can be charged / discharged while maximizing the power generation capability of the solar cell 11.

  Next, a sixth embodiment of the present invention will be described. FIG. 15: is a block diagram of the solar power generation device which concerns on the 6th Embodiment of this invention. In the sixth embodiment, an inverter output monitoring unit 27 is added to the fifth embodiment shown in FIG. 11, and the inverter output monitoring unit 27 is connected to the inverter during operation of the secondary battery 12. When the output power of 15 changes by a predetermined value or more, a command to disconnect the secondary battery 12 from the solar battery 11 is output to the secondary battery connection unit 22 and the solar cell operating voltage determination unit 18 is activated. Is. When activated, the solar cell operating voltage determination unit 18 determines whether or not the operating voltage Vp of the solar cell 11 is in the intermediate voltage range (Va <Vp <Vc), and the first secondary battery selection unit 19 or the second secondary battery selection unit 20 searches for the secondary battery 12 having a large output power again. The same elements as those in FIG. 11 are denoted by the same reference numerals, and redundant description is omitted.

  Now, it is assumed that the secondary battery 12c is connected in parallel to the solar battery 11 and is operated at the operating point C1c of the rated voltage Vc of the secondary battery 12c of the VI characteristic curve C1, as shown in FIG. The output power P of the solar cell 11 in this case is P1c determined by the VP characteristic curve P1. The operating point C11 is the optimum operating point for the maximum output P1max at which the output power of the solar cell 11 is maximized.

  In this state, if the sunshine intensity is changed and the VI characteristic curve C1 is changed to the VI characteristic curve C2, the operating point of the solar cell 11 is changed from the operating point C1c of the VI characteristic curve C2 to VI. The operating point C2c of the characteristic curve C2 is changed. Therefore, the output power P of the solar cell 11 changes from P1c determined by the VP characteristic curve P1 to P2c determined by the VP characteristic curve P2.

  The inverter output monitoring unit 27 monitors the change ΔP (= P1b−P2c) of the output power P. When the change ΔP of the output power P exceeds a predetermined value, a command to disconnect the secondary battery 12c from the solar cell 11 Is output to the secondary battery connection unit 22 and the solar cell operating voltage determination unit 18 of the secondary battery selection unit 17 is activated.

  When the secondary battery 12c is disconnected from the DC system 14 by the secondary battery connection unit 22, the maximum power tracking control unit 23 performs the maximum power tracking control, and the operating point of the solar cell 11 is the VI characteristic curve C2. The operating point C2c changes to the operating point C22 of the VI characteristic curve C2. Therefore, the output power P of the solar cell 11 changes from P2c determined by the VP characteristic curve P2 to P2max determined by the VP characteristic curve P2.

  The solar cell operating voltage determination unit 18 determines whether or not the operating voltage Vp (= Vp2) in the changed VI characteristic curve C2 is in the intermediate voltage range (Va <Vp <Vc), and the first secondary battery The selection unit 19 or the second secondary battery selection unit 20 searches the secondary batteries 12a, 12b, and 12c having a large output power again.

  This is because when the output power P of the solar battery 11 changes by a predetermined value or more, the operating point C2c is determined by the changed VI characteristic curve C2 according to the rated voltage Vc of the currently connected secondary battery 12c. This is because the output power P2c is not always close to the maximum output P2max determined by the changed VI characteristic curve C2.

  FIG. 16 shows a case where the operating voltage Vp (= Vp2) of the solar cell 11 is not in the intermediate voltage range (Va <Vp <Vc). Since the operating voltage Vp (= Vp2) of the solar cell 11 is not in the intermediate voltage range (Va <Vp <Vc), the operating point at which the output power P of the solar cell 11 becomes the maximum output P2max with the changed VI characteristic curve C2. The secondary battery 12 having a rated voltage close to the operating voltage Vp2 at C22 is searched again.

  On the other hand, when the operating voltage Vp of the solar cell 11 is in the intermediate voltage range (Va <Vp <Vc), the secondary battery selection unit 17 performs the processing shown in FIG. 13 or FIG. 14 of the first embodiment. Therefore, the secondary battery 12 having a large output power is searched again.

  Next, a seventh embodiment of the present invention will be described. FIG. 17 is a configuration diagram of a photovoltaic power generation apparatus according to the seventh embodiment of the present invention. In the seventh embodiment, a charging depth monitoring unit 28 is additionally provided to the fifth embodiment shown in FIG. 11, and the charging depth monitoring unit 28 includes three secondary batteries 12a and 12b. When the charging depth of 12c deviates from the predetermined range, a connection switching command is output to the secondary battery connecting portion 22 so that the charging depths of the three secondary batteries 12a, 12b, and 12c are equalized. When there is a request from the control unit 24, a charge / discharge command for equalizing the charging depth of the two secondary batteries 12a, 12b, 12c is output. The same elements as those in FIG.

  The charging depth monitoring unit 28 inputs the charging depths ca, cb, cc of the secondary batteries 12a, 12b, 12c, and the charging depths ca, cb, cc of the secondary batteries 12a, 12b, 12c are within a predetermined range (for example, 20 % To 80%) is judged. When the charging depths ca, cb, cc of the secondary batteries 12a, 12b, 12c deviate from a predetermined range (20% to 80%), a connection switching command is output to the secondary battery connection unit 22. Note that when the charging depths ca, cb, cc of the secondary batteries 12a, 12b, 12c do not deviate from the predetermined range (20% to 80%), the connection switching command is not output.

  Now, it is assumed that the storage amount of the secondary battery 12a is 90%, the storage amount of the secondary battery 12b is 10%, and the storage amount of the secondary battery 12c is 50%. Then, since the charging depth ca of the secondary battery 12a deviates from the predetermined range (20% to 80%) to the larger side, the charging depth monitoring unit 28 makes the secondary battery 12a to the secondary battery connection unit 22. The connection switching command for discharging is output. On the other hand, since the charging depth cb of the secondary battery 12b deviates from a predetermined range (20% to 80%) to a smaller side, the charging depth monitoring unit 28 makes the secondary battery 12b to the secondary battery connecting unit 22. The connection switching command for charging is output. Further, since the charging depth cc of the secondary battery 12c is within a predetermined range (20% to 80%), the charging depth monitoring unit 28 issues a connection switching command for the secondary battery 12c to the secondary battery connecting unit 22. Do not output. When the secondary battery connection unit 22 inputs the connection switching command from the charge depth monitoring unit 28, the secondary battery connection unit 22 stores the connection switching command.

  The secondary battery connection unit 22 waits for selection information of the secondary batteries 12a, 12b, and 12c from the first secondary battery selection unit 19 or the second secondary battery selection unit 20, and waits for the first secondary battery selection unit. 19 or whether the secondary battery 12 selected by the second secondary battery selection unit 20 matches the secondary battery 12 for which a connection switching command has been issued from the charge depth monitoring unit 28.

  If the secondary battery 12 selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20 does not match the secondary battery 12 for which the connection switching command has been issued from the charge depth monitoring unit 28, the secondary battery 12 The secondary battery connection unit 22 connects the secondary battery 12 selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20 to the DC system 14. At that time, one of the switching elements 26a and 26b of the switch circuit 13 is turned on according to the content of the charge / discharge command S from the outside.

  On the other hand, when the secondary battery 12 selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20 matches the secondary battery 12 for which a connection switching command has been issued from the charge depth monitoring unit 28. The secondary battery 12 is connected to the DC system 14 in accordance with the connection switching command. For example, when the secondary battery selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20 is the secondary battery 12a, the storage amount of the secondary battery 12a is 90%. Since the connection switching command from the charge depth monitoring unit 28 is a connection switching command for discharging, the secondary battery connection unit 22 outputs a command to turn on the switching element 26a2 of the switch circuit 13a. Thereby, the secondary battery 12a can be operated only with respect to the discharge command.

  On the other hand, when the secondary battery selected by the first secondary battery selection unit 19 or the second secondary battery selection unit 20 is the secondary battery 12b, the storage amount of the secondary battery 12b is 10%. Thus, since the connection switching command from the charge depth monitoring unit 28 is a connection switching command for charging, the secondary battery connection unit 22 outputs a command to turn on the switching element 26b1 of the switch circuit 13b. Thereby, the secondary battery 12b can be operated only with respect to the charge command.

  Next, the charge / discharge control unit 24 determines whether the external charge / discharge command S matches the charge / discharge by connection switching from the secondary battery connection unit 22. When the charge / discharge coincides, charge / discharge control is performed on the secondary batteries 12a, 12b in accordance with an external charge / discharge command.

  On the other hand, when the charge / discharge command S from the outside does not coincide with charge / discharge by connection switching from the secondary battery connection unit 22, the charge / discharge control unit 24 sends the secondary batteries 12 a and 12 b to the charge depth monitoring unit 28. The charge / discharge command is required to make the charge depth uniform. When the charge depth monitoring unit 28 receives a charge / discharge command request from the charge / discharge control unit 24, the charge depth monitoring unit 28 outputs a charge / discharge command that matches the connection command to the secondary battery connection unit 22. Accordingly, the charge / discharge control unit 24 performs charge / discharge control on the secondary battery 12 by the charge / discharge command from the charge depth monitoring unit 28 instead of the charge / discharge command S from the outside. That is, the charge / discharge control giving priority to the uniform charge depth of the secondary battery 12 is performed.

  The charge / discharge command from the charge depth monitoring unit 28 is, for example, a discharge command in which the storage amount of the secondary battery 12a is 50% of the reference value when the storage amount of the secondary battery 12a is 90%. If it is 10%, the charging command is 50% of the reference value. The charge / discharge control unit 24 performs charge / discharge based on the charge / discharge command from the charge depth monitoring unit 28. As a result, when the charge depth of the two secondary batteries 12a, 12b becomes uniform, the external charge / discharge command S Follow the instructions.

  According to the seventh embodiment, when the charging depth of the three secondary batteries 12a, 12b, and 12c is detected, and the charging depth of any of the secondary batteries 12a, 12b, and 12c deviates from the predetermined range, Performs charge / discharge control so that the charge depth becomes the reference value, so that the charge depth of each of the secondary batteries 12a, 12b, 12c becomes uniform.

  Next, an eighth embodiment of the present invention will be described. FIG. 18 is a configuration diagram of a photovoltaic power generation apparatus according to the eighth embodiment of the present invention. In the eighth embodiment, any one of the three secondary batteries 12a, 12b, and 12c is connected during the maximum power tracking control of the solar battery 11 with respect to the fifth embodiment shown in FIG. Instead, any one of the three secondary batteries 12a, 12b, and 12c is connected when the solar battery 11 is activated. Also in this case, the secondary battery selection unit 17 selects any of the secondary batteries 12a, 12b, and 12c in which the output power of the solar battery 11 is increased. The same elements as those in FIG. 11 are denoted by the same reference numerals, and redundant description is omitted.

  The secondary battery selection unit 17 is configured to be able to select the secondary batteries 12a, 12b, and 12c that increase the output power of the solar battery 11 when the solar battery 11 is activated. That is, the secondary battery selection unit 17 includes a solar cell activation unit 29, an output power increase direction determination unit 30, a provisional selection unit 31, a solar cell output power determination unit 32, and a final selection unit 33. Yes.

  The solar cell activation unit 29 of the secondary battery selection unit 17 activates the maximum power follow-up control unit 23 when the solar cell 11 is activated, and the operating voltage Vp of the solar cell 11 at that time is set to an intermediate voltage range (Va <Vp <Vc). ) To start the maximum power tracking control.

  The output power increase direction determination unit 30 of the secondary battery selection unit 17 determines the voltage direction in which the output power of the solar cell 11 is increased by the maximum power tracking control of the maximum power tracking control unit 23 activated by the solar cell activation unit 29. judge.

  Since the maximum power tracking control unit 23 starts the maximum power tracking control in the intermediate voltage range (Va <Vp <Vc), the output power of the solar cell 11 is not necessarily the maximum power at the start of the maximum power tracking control. Therefore, when the maximum power tracking control unit 23 starts the maximum power tracking control and changes the operating voltage, there is a voltage direction in which the output power increases. The output power increase direction determination unit 30 detects the voltage direction in which the output power at that time increases, and detects the increased output power of the solar cell 11.

  The temporary selection unit 31 of the secondary battery selection unit 17 has the maximum output power of the solar cell at the rated voltage among the secondary batteries 12 having the rated voltage in the voltage direction determined by the output power increase direction determination unit 30. Information on the selected secondary battery 12 is notified to the secondary battery connection unit 22 that tentatively selects the secondary battery 12 to be output.

  When the secondary battery connection unit 22 receives the notification of the secondary battery 12 selected by the temporary selection unit 31, the secondary battery connection unit 22 determines whether the external charge / discharge command S is a charge command or a discharge command, and the switch circuit 13 according to the charge / discharge command. The switching element 26 connects the secondary battery 12 to the solar battery 11 of the DC system 14 in parallel.

  The secondary battery connection unit 22 notifies the charge / discharge control unit 24 that the secondary battery 12 selected by the provisional selection unit 31 is connected to the DC system 14. Thereby, the charge / discharge control part 24 outputs the discharge command according to the charge / discharge command S from the outside to the inverter control part 25, and performs discharge control.

  Next, the solar cell output power determination unit 32 inputs the output power of the solar cell 11 at the rated voltage V of the secondary battery 12 selected by the provisional selection unit 31 from the maximum power follow-up control unit 23 and outputs the output power. The output power of the solar cell 11 when the voltage direction in which the output power increases is detected from the increase direction determination unit 30 is input.

  The solar cell output power determination unit 32 inputs the output power of the solar cell 11 at the rated voltage V of the secondary battery 12 selected by the provisional selection unit 31, and the output when the output power increase direction determination unit 30 determines It is determined whether or not it is greater than the power. Then, the determination result is output to the final selection unit 33.

  The final selection unit 33 determines that the output power of the solar cell 11 at the rated voltage V of the secondary battery 12 selected by the temporary selection unit 31 is the output power increase direction determination unit 30 based on the determination result of the solar cell output power determination unit 32. If it is determined that the output power is greater than that determined in step (b), the secondary battery 12 selected by the provisional selection unit 31 is selected. Since the secondary battery 12 selected by the provisional selection unit 31 is already connected in parallel to the solar battery 11 of the DC system 14, it is left as it is.

  On the other hand, when the output power of the solar cell 11 at the rated voltage V of the secondary battery 12 selected by the temporary selection unit 31 is determined by the output power increase direction determination unit 30 based on the determination result of the solar cell output power determination unit 32. When it is determined that the output power is smaller than the output power of the secondary battery 12 having the rated voltage in the direction opposite to the voltage direction determined by the output power increasing direction determination unit 30, the final selection unit 33 uses the rated voltage. The output power P of the solar battery at the rated voltage of the secondary battery 12 at which the output power P of the solar battery 11 becomes the maximum output is obtained and compared with the output power P of the secondary battery 12 selected by the provisional selection unit 31. Then, the secondary battery 12 with the larger output power is selected.

  FIG. 19 is a graph of the VI characteristics and VP characteristics of a solar cell showing an example of the operation of the solar power generation apparatus according to the eighth embodiment of the present invention. FIG. 19 shows a VI characteristic curve C1 and a VP characteristic curve P1 using the solar radiation intensity when the temperature of the solar cell 11 is constant as a parameter, and shows three secondary batteries 12a, 12b, 12c. The case of (rated voltage Va, Vb, Vc) is shown.

  When the solar cell 11 is activated, the maximum power follow-up control unit 23 is activated. As shown in FIG. 19, the operating voltage Vp1 of the solar cell 11 is the rated voltages Va, Vb of the three secondary batteries 12a, 12b, 12c, Maximum power follow-up control is started in the intermediate voltage range of Vc. The output power of the solar cell 11 at this time is P1p. Since the output power of the solar battery 11 is not necessarily the maximum output power at the start of the maximum power tracking control, there is a voltage direction in which the output power increases.

  FIG. 19 shows a case where the operating voltage Vp1 'is moved in the positive direction by a minute voltage ΔV to obtain the operating voltage Vp1'. In the operating voltage Vp1 ′ in which the operating voltage Vp1 is changed by ΔV in the positive direction by this maximum power tracking control, the output power of the solar cell 11 is P1p ′, and P1p ′> P1p. Therefore, the operating voltage Vp1 is set in the positive direction. When moved, it turns out that the output electric power of the solar cell 11 is increasing. The output power increase direction determination unit 30 detects the voltage direction (positive direction) in which the output power increases and also detects the increased output power P1p ′ of the solar cell 11.

  Next, the temporary selection unit 31 has the maximum output power of the solar cell at the rated voltage among the secondary batteries 12 having the rated voltage in the voltage direction (positive direction) determined by the output power increase direction determination unit 30. The secondary battery 12 to be output is temporarily selected. When there are a plurality of secondary batteries 12 in the voltage direction (Vp1 → Vp1 ′) in which the operating voltage Vp1 is increased, the provisional selection unit 31 activates the solar cell output power determination unit 32 to The output power of the solar battery at the rated voltage of the secondary battery 12 is obtained, and among these secondary batteries 12, the secondary battery 12 having the maximum output power of the solar battery is provisionally selected. In the case of FIG. 19, since there is only the secondary battery 12c having the rated voltage Vc in the voltage direction (positive direction) determined by the output power increase direction determination unit 30, the secondary battery 12c is provisionally selected.

  And the solar cell output power determination part 32 calculates | requires the output power P1c of the solar cell 11 in the rated voltage Vc of the secondary battery 12c selected provisionally, and increased output power P1p 'at the time of the start of maximum power follow-up control Determine if greater than. In FIG. 19, P1c> P1p ′.

  The final selection unit 33 selects the secondary battery 12c because the output power P1c of the solar battery 11 at the rated voltage Vc of the secondary battery 12c is greater than the increased output power P1p ′ at the start of the maximum power tracking control. . Since the secondary battery 12c is already connected in parallel to the solar battery 11 of the DC system 14, it is left as it is. In this case, it is found that the secondary battery 12c is a secondary battery that is obtained by merely operating the maximum power tracking control unit 23 at the rated voltage Vc of the secondary battery 12c.

  FIG. 20 is a graph of the VI characteristics and VP characteristics of a solar cell showing another example of the operation of the photovoltaic power generation apparatus according to the eighth embodiment of the present invention. FIG. 20 shows the VI characteristic curve C2 and the VP characteristic curve P2 using the solar radiation intensity when the temperature of the solar cell 11 is constant as a parameter, and the voltage direction (Vp2 → Vp2 ′) includes a plurality of (two) secondary batteries 12b and 12c (rated voltages Vb and Vc), and the secondary battery 12b having the larger output power increases the output power at the start of the maximum power tracking control. The case where it is smaller than P2p ′ is shown.

  As in the case of FIG. 19, when the solar cell 11 is started, the operating voltage Vp2 of the solar cell 11 is the maximum power in the intermediate voltage range of the rated voltages Va, Vb, Vc of the three secondary batteries 12a, 12b, 12c. Follow-up control is started.

  Similarly to the case of FIG. 19, when the operating voltage Vp2 is moved in the positive direction by a minute voltage ΔV to be the operating voltage Vp2 ′, the output power of the solar cell 11 is P2p ′, and Vp2 ′> Vp2. When the operating voltage Vp2 is moved in the positive direction, it can be seen that the output power P of the solar cell 11 is increased. The output power increase direction determination unit 30 detects the voltage direction (positive direction) in which the output power P increases, and detects the increased output power P2p ′ of the solar cell 11.

  Next, the provisional selection unit 31 outputs the output power of the solar cell 11 among the secondary batteries 12b and 12c (rated voltages Vb and Vc) in the voltage direction (positive direction) determined by the output power increase direction determination unit 30. Tentatively selects the secondary battery 12 with the maximum output. In the case of FIG. 19, since the output power P2b of the rated voltage Vb is larger than the output power P2c of the rated voltage Vc, the secondary battery 12b of the rated voltage Vb is provisionally selected.

  Then, the solar cell output power determination unit 32 determines whether or not the output power P2b of the solar cell 11 at the rated voltage Vb of the secondary battery 12b is larger than the increased output power P2p ′ at the start of the maximum power tracking control. To do. In FIG. 20, P2b <P2p ′.

  Since the output power P2b of the solar cell 11 at the rated voltage Vb of the secondary battery 12b is smaller than the increased output power P2p ′ at the start of the maximum power follow-up control, the final selection unit 33 determines whether the output power increase direction determination unit 30 Among the secondary batteries 12 having a rated voltage in the opposite direction to the determined voltage direction, the output power of the solar battery at the rated voltage of the secondary battery 12 at which the output power P of the solar battery 11 is the maximum output is obtained, and provisional The output power of the secondary battery 12 selected by the selection unit 31 is compared, and the secondary battery 12 with the larger output power P is selected.

  In the case of FIG. 20, since there is only the secondary battery 12 a in the opposite direction to the voltage direction determined by the output power increase direction determination unit 30, the final selection unit 33 selects the secondary battery selected by the provisional selection unit 31. The output power P2b of the solar cell 11 at the rated voltage Vb of 12b is compared with the output power P2a of the solar cell 11 at the rated voltage Va of the secondary battery 12a. In FIG. 20, since P2a <P2b, the final selection unit 33 selects the secondary battery 12b having the larger output power P. When P2a> P2b, the secondary battery 12a is selected.

  In the eighth embodiment, when any one of the secondary batteries 12a, 12b, and 12c is connected at the time of starting the solar battery 11, the maximum power follow-up control unit 23 is started, and the three secondary batteries 12a, The maximum power follow-up control is started in the intermediate voltage range of the rated voltages Va, Vb, Vc of 12b, 12c, and the secondary battery 12 of the rated voltage in the voltage direction in which the output power of the solar battery 11 is increased by the maximum power follow-up control. Of these, the secondary battery 12 with the maximum output is provisionally selected. Then, it is determined whether or not the output power of the solar battery 11 at the rated voltage of the secondary battery 12 is larger than the output power when the voltage direction is determined, and if it is greater, the secondary battery 12 is selected.

  On the other hand, when the output power of the solar battery 11 at the rated voltage of the temporarily selected secondary battery 12 is smaller than the output power when the voltage direction is determined, the voltage direction determined by the output power increase direction determination unit 30 And the output power of the solar cell 11 at the rated voltage of the secondary battery 12 in the opposite direction. Then, the secondary battery with the larger output power is selected. Therefore, even when three or more secondary batteries are connected, a secondary battery that maximizes the power generation capability of the solar battery can be selected.

DESCRIPTION OF SYMBOLS 11 ... Solar cell, 12 ... Secondary battery, 13 ... Switch circuit, 14 ... DC system, 15 ... Inverter, 16 ... AC system, 17 ... Secondary battery selection part, 18 ... Solar cell operating voltage determination part, 19 ... 1st DESCRIPTION OF SYMBOLS 1 Secondary battery selection part, 20 ... 2nd secondary battery selection part, 21 ... Control part, 22 ... Secondary battery connection part, 23 ... Maximum electric power follow-up control part, 24 ... Charge / discharge control part, 25 ... Inverter control part , 26 ... switching element, 27 ... inverter output monitoring unit, 28 ... charge depth monitoring unit, 29 ... solar cell activation unit, 30 ... output power increase direction determination unit, 31 ... provisional selection unit, 32 ... solar cell output power determination unit 33 ... Final selection part

Claims (10)

A solar cell that generates direct-current power from sunlight;
Two secondary batteries with different rated voltages;
A switch circuit for connecting two secondary batteries to the solar cell in parallel;
A secondary battery selection unit for selecting a secondary battery connected in parallel to the solar battery;
An inverter that converts the DC power of the DC system of the solar battery and the secondary battery into AC and outputs the AC power, or converts the AC power of the AC system into DC power and outputs it to the DC system;
A controller for operating the solar cell and performing charge / discharge control of the secondary battery by the inverter;
The controller is
A secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit;
A maximum power tracking control unit that performs maximum power tracking control so that the output power of the solar cell is the maximum power;
A charge / discharge control unit for performing charge / discharge control of the secondary battery;
An inverter control unit for controlling the inverter based on a command from the maximum power follow-up control unit and the charge / discharge control unit;
The secondary battery selector is
When charge / discharge control of the secondary battery is required during the maximum power tracking control in the maximum power tracking control unit, the operating voltage of the solar cell by the maximum power tracking control is A solar cell operating voltage determination unit that determines whether or not an intermediate voltage range that is greater than or equal to the smaller voltage value of the rated voltage and less than or equal to the larger voltage value;
A first secondary battery selection unit that selects a secondary battery having a rated voltage close to the operation voltage of the solar cell when the solar cell operating voltage determination unit determines that the operating voltage of the solar cell is not in the intermediate voltage range. When,
When the solar cell operating voltage determination unit determines that the operating voltage of the solar cell is in the intermediate voltage range, the maximum power follow-up is performed so that each of the solar cells is operated at the rated voltage of two secondary batteries. A second secondary battery selection unit that outputs a command to the control unit and selects a secondary battery having a larger output power when the solar cell is operated by the maximum power follow-up control unit;
The secondary battery connection unit of the control device uses the switch circuit to connect the secondary battery selected by the first secondary battery selection unit or the second secondary battery selection unit of the secondary battery selection unit to the direct current. A solar power generation device connected in parallel to the solar cell of a system.   The second secondary battery selection unit of the secondary battery selection unit has two secondary batteries when the solar cell operation voltage determination unit determines that the operation voltage of the solar cell is in the intermediate voltage range. Instead of operating each of the solar cells at the rated voltage of the battery, an approximate curve of the output voltage-output power characteristic of the solar cell in the vicinity of the operating voltage of the solar cell at that time is calculated, and based on the approximate curve The solar power generation device according to claim 1, wherein a secondary battery having a larger output power when the operating voltage of the solar battery is set to a rated voltage of two secondary batteries is selected.   When the output power of the inverter changes by a predetermined value or more during operation of the secondary battery, the control device outputs a command to disconnect the secondary battery from the solar battery to the secondary battery connection unit. 3. The photovoltaic power generation apparatus according to claim 1, further comprising an inverter output monitoring unit that activates the solar cell operating voltage determination unit, and searching for the secondary battery again. 4.   The control device switches the connection to the secondary battery connection unit so that the charge depth of the two secondary batteries becomes uniform when the charge depth of either of the two secondary batteries deviates from a predetermined range. A charge depth monitoring unit that outputs a command, and the charge depth monitoring unit outputs a charge / discharge command for equalizing the charge depth of two secondary batteries when requested by the charge / discharge control unit. The photovoltaic power generation apparatus according to claim 1, wherein the photovoltaic power generation apparatus outputs to a discharge control unit. A solar cell that generates direct-current power from sunlight;
Two secondary batteries with different rated voltages;
A switch circuit for connecting two secondary batteries to the solar cell in parallel;
A secondary battery selection unit for selecting a secondary battery connected in parallel to the solar battery;
An inverter that converts the DC power of the DC system of the solar battery and the secondary battery into AC and outputs the AC power, or converts the AC power of the AC system into DC power and outputs it to the DC system;
A controller for operating the solar cell and performing charge / discharge control of the secondary battery by the inverter;
The controller is
A secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit;
A maximum power tracking control unit that performs maximum power tracking control so that the output power of the solar cell is the maximum power;
A charge / discharge control unit for performing charge / discharge control of the secondary battery;
An inverter control unit for controlling the inverter based on a command from the maximum power follow-up control unit and the charge / discharge control unit;
The secondary battery selector is
When the solar cell is activated, the maximum power follow-up control unit is activated and maximum power follow-up control is started in an intermediate voltage range that is greater than or equal to the smaller voltage value of the two secondary batteries and less than or equal to the greater voltage value. A solar cell starting unit
An output power increase direction determination unit that determines a voltage direction in which the output power of the solar cell is increased by the maximum power tracking control of the maximum power tracking control unit started by the solar cell starting unit;
A provisional selection unit that provisionally selects a secondary battery having a rated voltage in the voltage direction determined by the output power increase direction determination unit;
Solar cell output power determination for determining whether the output power of the solar cell at the rated voltage of the secondary battery selected by the provisional selection unit is larger than the output power as determined by the output power increase direction determination unit And
It is determined that the output power of the solar cell at the rated voltage of the secondary battery selected by the temporary selection unit by the solar cell output power determination unit is larger than the output power when the output power increase direction determination unit determines. If so, the secondary battery is selected. Otherwise, the output power of the solar battery at the rated voltage of the other secondary battery is compared with the output power of the secondary battery selected by the temporary selection unit. A solar power generation device comprising: a final selection unit that selects a secondary battery having a larger output power. A solar cell that generates direct-current power from sunlight;
Three or more secondary batteries with different rated voltages;
A switch circuit for connecting three or more secondary batteries in parallel to the solar cell,
A secondary battery selection unit for selecting a secondary battery connected in parallel to the solar battery;
An inverter that converts the DC power of the DC system of the solar battery and the secondary battery into AC and outputs the AC power, or converts the AC power of the AC system into DC power and outputs it to the DC system;
A controller for operating the solar cell and performing charge / discharge control of the secondary battery by the inverter;
The controller is
A secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit;
A maximum power tracking control unit that performs maximum power tracking control so that the output power of the solar cell is the maximum power;
A charge / discharge control unit for performing charge / discharge control of the secondary battery;
An inverter control unit for controlling the inverter based on a command from the maximum power follow-up control unit and the charge / discharge control unit;
The secondary battery selector is
When charging / discharging control of the secondary battery is required during the maximum power tracking control in the maximum power tracking control unit, a secondary battery having three or more operating voltages of the solar cell by the maximum power tracking control A solar cell operating voltage determination unit that determines whether or not an intermediate voltage range that is greater than or equal to the minimum value of the rated voltage and less than or equal to the maximum value;
When the solar cell operating voltage determination unit determines that the operating voltage of the solar cell is not in the intermediate voltage range, a secondary battery having a rated voltage closest to the operating voltage of the solar cell is selected. And
When the solar cell operating voltage determination unit determines that the operating voltage of the solar cell is in the intermediate voltage range, the operating voltage of the solar cell is any two of the rated voltages of three or more secondary batteries. Determine which operating voltage range is sandwiched between the rated voltages and command the maximum power tracking control unit to operate the solar cells at the rated voltages of the two secondary batteries that form the operating voltage range. The secondary battery having a larger output power when the solar battery is operated by the maximum power tracking control unit is temporarily selected, and the operation of the rated voltage of the temporarily selected secondary battery is performed. The secondary battery having the maximum output power of the solar battery is selected including the secondary battery temporarily obtained by obtaining the output power of the solar battery at the rated voltage of the secondary battery outside the voltage range. 2 with a secondary battery selector
The secondary battery connection unit of the control device uses the switch circuit to connect the secondary battery selected by the first secondary battery selection unit or the second secondary battery selection unit of the secondary battery selection unit to the direct current. A solar power generation device connected in parallel to the solar cell of a system.   The second secondary battery selection unit of the secondary battery selection unit is configured to operate the solar cell when the solar cell operating voltage determination unit determines that the operating voltage of the solar cell is in the intermediate voltage range. Determine which operating voltage range is sandwiched between any two of the rated voltages of secondary batteries with a voltage of 3 or more, and the rated voltages of the two secondary batteries that form the operating voltage range Instead of operating each of the solar cells, an approximate curve of the output voltage-output power characteristics of the solar cell in the vicinity of the operating voltage of the solar cell at that time is calculated, and the solar cell based on the approximate curve When the operating voltage of the secondary battery is the rated voltage of the two secondary batteries, the secondary battery whose output power is larger is temporarily selected, and the operation of the rated voltage of the temporarily selected secondary battery is performed. Ratings of secondary batteries outside the voltage range The secondary battery having the maximum output power of the solar cell is selected including the secondary battery obtained by temporarily obtaining the output power of the solar cell based on the approximate curve based on the approximate curve. Item 7. The solar power generation device according to item 6.   When the output power of the inverter changes by a predetermined value or more during operation of the secondary battery, the control device outputs a command to disconnect the secondary battery from the solar battery to the secondary battery connection unit. The solar power generation device according to claim 6, further comprising an inverter output monitoring unit that activates the solar cell operating voltage determination unit, and searching for the secondary battery again.   The control device connects the secondary battery so that the charging depth of three or more secondary batteries becomes uniform when the charging depth of any of the three or more secondary batteries deviates from a predetermined range. A charging depth monitoring unit that outputs a connection switching command to the charging unit, and the charging depth monitoring unit charges the charging depth of three or more secondary batteries to be uniform when requested by the charging / discharging control unit. The photovoltaic power generation apparatus according to claim 6 or 7, wherein a discharge command is output to the charge / discharge control unit. A solar cell that generates direct-current power from sunlight;
Three or more secondary batteries with different rated voltages;
A switch circuit for connecting three or more secondary batteries in parallel to the solar cell,
A secondary battery selection unit for selecting a secondary battery connected in parallel to the solar battery;
An inverter that converts the DC power of the DC system of the solar battery and the secondary battery into AC and outputs the AC power, or converts the AC power of the AC system into DC power and outputs it to the DC system;
A controller for operating the solar cell and performing charge / discharge control of the secondary battery by the inverter;
The controller is
A secondary battery connection unit that connects the secondary battery selected by the secondary battery selection unit in parallel to the solar cell of the DC system by the switch circuit;
A maximum power tracking control unit that performs maximum power tracking control so that the output power of the solar cell is the maximum power;
A charge / discharge control unit for performing charge / discharge control of the secondary battery;
An inverter control unit for controlling the inverter based on a command from the maximum power follow-up control unit and the charge / discharge control unit;
The secondary battery selection unit activates the maximum power follow-up control unit at the time of startup of the solar battery, and follows the maximum power in an intermediate voltage range that is greater than or equal to the minimum value of the rated voltages of three or more secondary batteries and less than or equal to the maximum value. A solar cell starter for starting control;
An output power increase direction determination unit that determines a voltage direction in which the output power of the solar cell is increased by the maximum power tracking control of the maximum power tracking control unit started by the solar cell starting unit;
Temporary selection for tentatively selecting a secondary battery having the maximum output power of the solar battery at the rated voltage among the secondary batteries having a rated voltage in the voltage direction determined by the output power increase direction determination unit And
Solar cell output power determination for determining whether the output power of the solar cell at the rated voltage of the secondary battery selected by the provisional selection unit is larger than the output power as determined by the output power increase direction determination unit And
It is determined that the output power of the solar cell at the rated voltage of the secondary battery selected by the temporary selection unit by the solar cell output power determination unit is larger than the output power when the output power increase direction determination unit determines. The secondary battery is selected, and if not, the solar battery at the rated voltage among the secondary batteries having the rated voltage in the direction opposite to the voltage direction determined by the output power increase direction determining unit. The output power of the solar battery at the rated voltage of the secondary battery with the maximum output power of the secondary battery is compared with the output power of the secondary battery selected by the provisional selection unit. And a final selection unit for selecting the solar power generation device.

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