JPH0833785B2 - Control method of reactive power generation device and reactive power generation device - Google Patents

Description

The present invention relates to a reactive power generator (SVG) control method and a reactive power generator (SVG) that generate a variable-capacity reactive power according to the voltage of a power system. ) Is related to.

[Conventional technology]

FIG. 4 is a schematic configuration diagram showing a conventional reactive power generator (SVG) shown on page 187 of the collection of papers of the Tokyo Institute of Electrical Engineers, Tokyo Branch (Niigata area), 1978, for example.
1 is a power system, Vs is a system voltage of the power system 1, 2 is a self-excited voltage type inverter (hereinafter simply referred to as an inverter) connected to the power system 1, L is a power system 1 and an inverter 2
, R is also a resistor, Vi is the output voltage of the inverter 2, 3 is a DC smoothing capacitor connected to the inverter 2, 4 is a current detector for detecting the actual value of the current of the power system 1, 5 is a phase detector that detects the voltage phase of the power system 1, 6 is the invalid value that calculates the actual value of the reactive current from the actual value of the current detected by the current detector 4 and the voltage phase detected by the phase detector 5. A current calculator 7 is a reactive current controller for calculating a control signal for controlling the output voltage Vi of the inverter 2 from the actual reactive current value calculated by the reactive current calculator 6. A pulse controller 8 generates a gate pulse signal to be supplied to the inverter 2 based on the control signal calculated by the reactive current controller 7.

FIG. 5 is a block diagram of the reactive current controller 7 of FIG.
The same parts as those in FIG. 4 are designated by the same reference numerals. In addition,
The configuration of FIG. 5 is shown as a conventional method of controlling the reactive power generator (SVG), for example, in Japanese Patent Publication No. 56-47564. In FIG. 5, 7a is a setter for setting the target value of the reactive current, 7b is a subtraction element for subtracting the actual reactive current value calculated by the reactive current calculator 6 from the reactive current target value, and 7c is a subtraction element. It is a reactive current regulator that generates the control signal based on the output of 7b and supplies it to the pulse controller 8.

Next, the operation will be described. This device controls the reactive current actual value calculated by the reactive current calculator 6 to match the reactive current target value set by the setter 7a. First, based on the actual value of the current of the electric power system 1 detected by the current detector 4 and the voltage phase of the electric power system 1 detected by the phase detector 5, the reactive current calculator 6 calculates the actual reactive current value. calculate.
Next, in FIG. 5, the subtraction element 7b calculates the difference between the actual reactive current value and the reactive current target value, and the reactive current regulator 7c controls the output voltage Vi of the inverter 2 in accordance with this difference. Calculate the signal. Based on this control signal, the pulse controller 8 generates a gate pulse signal that directly controls the inverter 2. As a result, the output voltage Vi of the inverter 2
Is controlled so that the actual reactive current value matches the reactive current target value. The capacitor 3 connected to the inverter 2 smoothes the DC voltage in the inverter 2.

FIG. 6 shows a reactive power generator (SV
G is for explaining the operation, Vi is the output voltage of the inverter 2, Vs is the system voltage of the power system 1, and X is the reactance consisting of the inductor L and the resistor R between the inverter 2 and the power system 1. The output voltage Vi has the same phase as the system voltage Vs, and only its magnitude is controlled. At this time, the actual reactive current value 1q from the electric power system 1 is approximately given by the following equation.

Therefore, when the reactive current actual value 1q is smaller than the reactive current target value, a control signal for increasing the output voltage Vi of the inverter 2 is generated from the reactive current regulator 7c to increase the reactive current actual value Iq, Conversely, when the reactive current actual value is larger than the reactive current target value, the output voltage Vi is reduced to reduce the reactive current actual value Iq.

However, in the transient state, when the output voltage Vi is suddenly changed, an active current flows between the power system 1 and the inverter 2, and as a result, the DC smoothing capacitor 3 is charged and discharged. Therefore, the voltage across the capacitor 3 fluctuates, and the output voltage Vi of the inverter 2 fluctuates accordingly, and the desired reactive current cannot be obtained. Therefore, it is necessary to slowly change the reactive current target value.

[Problems to be Solved by the Invention]

Since the conventional reactive power generator (SVG) is configured as described above, when the reactive current target value set by the setter 7a suddenly changes, the actual reactive current value matches the reactive current target value. Until the response time becomes slower, and if the response time is attempted to be increased, the actual value of the reactive current becomes unstable and the voltage fluctuation applied to the capacitor 3 is large. Therefore, it is necessary to increase the capacitance of the capacitor 3. There was such a problem.

The present invention has been made to solve the above-mentioned problems, and when the reactive current target value set by the setter changes abruptly, the reactive current actual value is promptly and stably provided. You can match the target value,
An object of the present invention is to obtain a reactive power generation device (SVG) control method and a reactive power generation device that can reduce the voltage fluctuation applied to the capacitor 3 and reduce the capacitance of this capacitor.

[Means for solving the problem]

A control method for a reactive power generator according to a first aspect of the invention is to detect an active current input to and output from a self-excited voltage type inverter and to correct the control signal by this active current. .

A reactive power generation device according to a second aspect of the invention is a multiplier for multiplying the active current detected by the detection means by a predetermined value,
The output signal from the multiplier and the control signal are added to each other to provide a correction control signal.

[Action]

The control method of the reactive power generator according to the first claim is,
Since the output voltage of the inverter is controlled by the correction control signal, charging / discharging of the DC smoothing capacitor is suppressed,
Fluctuations in the output voltage of the inverter are reduced.

In the reactive power generator according to the second aspect, a signal obtained by multiplying the active current by a predetermined value by a multiplier and a control signal are added by an adder to form a correction control signal. Is controlled, charge / discharge of the DC smoothing capacitor is suppressed, and fluctuations in the output voltage of the inverter are reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and description thereof will be omitted. Reference numeral 9 is an active current calculator that calculates the actual active current value of the power system 1 based on the actual value of the current detected by the current detector 4 and the voltage phase detected by the phase detector 5. The active current calculator 9, the current detector 4, and the phase detector 5 constitute a detecting means for detecting the actual active current value.

Reference numeral 10 is a correction means for correcting the control signal obtained from the reactive current controller 7 according to the actual value of the active current, and supplying the corrected control signal to the pulse controller 8. In this embodiment, the reactive current auxiliary control is performed. Vessel 10 is used.

FIG. 2 shows the structure of the reactive current auxiliary controller 10 and other related parts. The same parts as those in FIGS. 1 and 5 are designated by the same reference numerals. In FIG. 2, 10a is a multiplier for multiplying the actual active current value obtained from the active current calculator 9 by a predetermined constant K, and 10b is an output signal of the multiplier 10a and a control signal obtained from the reactive current regulator 7c. It is an adder that adds and supplies the added signal as a corrected control signal (correction control signal) to the pulse controller 8.

Next, the operation will be described. This device controls the actual reactive current value calculated by the reactive current calculator 6 to match the reactive current target value set by the setter 7a, as in the conventional case. Therefore, in the same manner as in the conventional case, the reactive current adjuster 7c obtains a control signal for matching the actual reactive current value with the reactive current target value. On the other hand, the active current calculator 9 calculates the active current actual value of the electric power system 1 based on the actual value of the current and the voltage phase, and adds it to the multiplier 10a in FIG. The multiplier 10a multiplies the active current actual value by K, and the product value thereof is added to the control signal obtained from the reactive current regulator 7c in the addition element 10b to correct this control signal. The pulse controller 8 generates a gate pulse signal according to the corrected control signal (correction control signal), and the output voltage Vi of the inverter 2 is controlled by this.

In the steady state, the reactive power generator (SVG) is the sixth
The operation is performed as described above with reference to the figure. At this time, the reactive current actual value Iq of the power system 1 is represented by the above equation.

Therefore, if the output voltage Vi of the inverter 2 is increased, the reactive current actual value Iq is increased, and if the output voltage Vi is decreased, the reactive current actual value Iq is decreased.

However, in the transient state, when the output voltage Vi is suddenly changed, an active current flows between the power system 1 and the inverter 2. Therefore, this actual active current value is calculated by the active current calculator 9 and multiplied by a predetermined constant K, and the value of this product is added to the control signal obtained from the reactive current regulator 7c,
This control signal is corrected. As a result, the charging / discharging of the DC smoothing capacitor 3 is suppressed by the value of the product added to the control signal, so that the voltage across the capacitor 3 does not fluctuate much, and therefore the output voltage of the inverter 2 is reduced.
The fluctuation of Vi is also small. That is, even when the reactive current target value suddenly changes, it is possible to control so that a desired reactive current can be obtained at high speed.

In the above embodiment, the actual active current value of the power system 1 is detected by the active current calculator 9, but as shown in FIG. 3, the capacitor current flowing to the DC smoothing capacitor 3 is The detector 11 for detecting may be provided as the detecting means. Because, when the active current flows, a capacitor current of a size corresponding to the active current flows, so that a constant K is added to the capacitor current detected by the detector 11 as shown in FIG.
Even if the control signal is corrected by multiplying by, the same effect as in the above embodiment can be obtained.

Further, in the above-described embodiment, the example in which the capacitor current of the DC smoothing capacitor 3 is directly detected has been described. However, the DC voltage applied across the capacitor 3 is detected, and the detected value is differentiated to obtain the capacitor current. The same effect can be obtained by calculation.

〔The invention's effect〕

As described above, according to the invention of the first aspect, the control signal for controlling the output voltage of the inverter is configured to be corrected according to the effective current input / output by the self-excited voltage type inverter. Since the actual reactive current value can be quickly and stably matched to the reactive current target value and the DC voltage fluctuation can be reduced, the DC smoothing capacitor can be made small in capacity, and the device is small and inexpensive. There is an effect.

Further, according to the invention of the second aspect, since the signal obtained by multiplying the effective current by the multiplier by the predetermined number and the control signal are added by the adder to obtain the correction control signal, the reactive current actual value is set. Can be quickly and stably matched to the reactive current target value, and the DC voltage fluctuation can be reduced, so that the capacity of the DC smoothing capacitor can be reduced, and the device is small and inexpensive. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a reactive power generator (SVG) according to an embodiment of the present invention, FIG. 2 is a configuration diagram showing a reactive current controller of the same, and FIG. 3 is another embodiment of the present invention. 4 is a schematic configuration diagram showing a reactive power generator (SVG) according to an example, FIG.
FIG. 1 is a schematic configuration diagram showing a conventional reactive power generator (SVG), FIG. 5 is a configuration diagram showing a reactive current controller of the same device, and FIG. 6 is a schematic configuration diagram for explaining the operation of the device. is there. 1 is a power system, 2 is a self-exciting voltage type inverter, 4 is a current detector, 5 is a phase detector, 6 is a reactive current calculator, 7 is a reactive current controller, 9 is an active current calculator, and 10 is a reactive current. Auxiliary controller. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Mie Ishizaki, Mie Ishizaki 6-1-2 Hamayama-dori, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Electric Control Software Co., Ltd. (72) Inventor Yasuhiko Hosokawa Wadazaki, Hyogo-ku, Kobe-shi, Hyogo 1-2, Machi, Mitsubishi Electric Corporation Control Works (56) Reference JP 62-118414 (JP, A)

Claims (2)

[Claims] 1. A control for connecting an electric power system and a self-excited voltage type inverter to control an output voltage of the self-excited voltage type inverter so that an actual reactive current value of the electric power system matches a reactive current target value. In a method of controlling a reactive power generator that obtains a signal, a reactive power characterized by detecting an active current input to and output from the self-excited voltage type inverter and correcting the control signal according to the detected active current. Generator control method. 2. A control for connecting an electric power system and a self-excited voltage type inverter, and controlling an output voltage of the self-excited voltage type inverter so that an actual reactive current value of the electric power system matches a reactive current target value. In a reactive power generation device that obtains a signal, a detection unit that detects an active current input and output by the self-excited voltage type inverter, a multiplier that multiplies the active current detected by the detection unit by a predetermined constant, and the multiplier. And the control signal, and an adder that uses the added output signal as a correction control signal.