JPS59149773A - Controller for self-excited power converter - Google Patents

Abstract

PURPOSE:To eliminate the mutual interference by applying a correction command from at least one control system to the other control system of effective and reactive power control systems. CONSTITUTION:The DC output of a fuel battery 1 is converted by an inverter 2 into an AC, and supplied to a power system 4 through a transmission line 3. The outputs of an effective power setter 13 and a reactive power setter 14 are respectively compared by comparators 9, 15 with effective and reactive powers, the deviation is applied to an effective power control arithmetic unit 15 and a reactive power control arithmetic unit 16, and PID-calculated. The outputs of the unit 15, 16 are respectively applied to comparators 11, 12, a voltage correcting coefficient unit 17 and a phase correcting coefficient unit 18. The outputs of the comparators 11, 12 are applied to a phase control arithmetic circuit 19 and a voltage control arithmetic circuit 20, and control signals from the circuits 19, 20 are applied to an inverter 2 through a waveform controller 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a self-excited power converter that supplies power from a DC power source such as a fuel cell to an AC power system.

[Technical background of the invention]

For example, conventional power generation methods, such as those found in thermal power plants, which convert the energy contained in fuel into electrical energy through many conversion processes, have poor energy conversion efficiency. chemically changed,
Attempts are being made to put into practical use a fuel cell power generation system that directly extracts electrical energy from the flow of electrons generated during this chemical change.

In this case, the power generated from the fuel cell is direct current, so it must be converted to alternating current in order to output it to the normal power system. , this is called an inverter) is used.

Conventionally, the phase of the inverter output voltage was controlled to control the active power supplied from the inverter to the power system, and the magnitude of the inverter output voltage was controlled to control the reactive power.

[Problems with background technology]

However, according to the conventional control method described above, the active power control system and the reactive power control system interfere with each other, and it takes a long time to settle down to a steady state after applying a control operation. There was a problem that certain inverter control was not performed.

That is, now the output voltage of the inverter is vo, the voltage of the power grid is vL1, the phase difference between the inverter output voltage and the power grid voltage is θ, and the interconnection impedance of the power transmission line until the inverter is connected to the power grid is 2. Then, the active power P and reactive power Q output from the inverter are as follows (i), (
2) Given by Eq.

As is clear from these equations, the active power P is not necessarily a function of only the phase difference θ, but is also related to the inverter output voltage V. Further, the reactive power Q is not necessarily a function of only the inverter output voltage v1, but is also related to the phase difference θ.

Therefore, according to the conventional control method described above, when the phase difference θ (inverter output voltage V,) is changed in an attempt to change the active power P (reactive power Q), the active power P (reactive power Q) is Therefore, the reactive power Q (active power P) also changes. Therefore, if the inverter output voltage V, (phase difference θ) is corrected according to the change in this reactive power Q (active power P), the controlled active power P (reactive power Q)
It takes a long time to change and settle down to a steady state.

On the other hand, power system stabilization, sudden changes in system load during system faults,
In order to respond to sudden changes in power supply in the event of a generator failure in a power system, a stable and quick response of the supplied active power and reactive power is required. In this regard, fuel cells and the like are expected to meet the above requirements because their power generation method does not involve thermal energy, and their output response characteristics are quick. However, the conventional inverter control method has
As mentioned above, there is a problem that the response speed is slow,
There was also the problem that the advantage of interconnectivity that the DC power source of Fuel Cell Gin had could not be utilized effectively.

[Purpose of the invention]

The present invention aims to eliminate mutual interference between active power control and reactive power control, which was unavoidable in conventional inverter control, and to provide a stable and coordinated inverter control device that can independently execute each control. purpose.

[Summary of the invention]

Therefore, the present invention is characterized in that mutual interference is eliminated by applying a correction command from at least one of the active power control system and the reactive power control system to the other control system.

[Embodiments of the invention]

FIG. 1 shows a configuration diagram of an inverter control device according to an embodiment of the present invention, and 1 is a fuel cell. The DC output of the fuel cell 1 is converted into AC by an inverter 2, and is supplied to the power system 4 via a power transmission line 3. At this time, the output voltage of the inverter 2 is vl, the active power is P1, and the reactive power is Q.

Further, the interconnection impedance of the power transmission line 3 is assumed to be L, which is the voltage of the 21 power system 4. 5 is an active power detector, 6 is a reactive power detector, 7 is a phase detector, and 8 is a voltage detector.

The outputs s, ts, , sθ of each of these detectors.

Sy are applied to comparators 9, 10, 11.12, respectively. 13 is an active power setting device, and 14 is a reactive power setting device. The output 5ill +814 from each of these setting devices is compared with SP, S, respectively, and the deviation is added to the active power control calculator 15, the reactive power control calculator 15, and the reactive power control calculator 16. , integral, differential) are calculated. As a result, reactive power control calculator 1
5 is applied as a phase command signal X to a comparator 11 and a voltage correction coefficient section 17. Further, the output of the reactive power control calculator 16 is applied as a voltage command signal Y to the comparator 12 and the phase correction coefficient section 18. Each of the signals X and Y is multiplied by r in Gv and Gv in each thread count section 17.18, respectively, and is applied to a comparator 12.11 as a correction signal.

The phase deviation signal from the comparator 11 is sent to the phase control calculation circuit 19.
is added to the signal and converted into a phase control signal.

Further, the voltage deviation signal from the comparator 12 is applied to the voltage control calculation circuit 20 and converted into a voltage control signal. Each of these control signals is sent to the inverter 2 via the waveform control circuit 21.
The phase and magnitude of the voltage V output from the inverter 2 are adjusted so that the outputs of the comparators 11 and 12 are both 0, and the active power P and reactive power Q is controlled according to the set value.

In the above configuration, the gain Gv of the voltage correction coefficient unit 17 and the gain Gθ of the phase correction coefficient unit 18 are for eliminating interference between active power control and reactive power control. Considering a driving state where IR1vL=vLR1θ=θ8, Gv1Gθ at this time is set to the following values.

Also, consider a case where the output X of the active power control calculator 15 and the output Y of the reactive power control calculator 16 are calculated based on their respective deviation input signals, and each changes by ΔX and ΔY.

At this time, the inverter control device sends a composite value of the command signals for controlling the phase applied to the comparators 11 and 12, and a command signal for controlling the voltage (ΔX-
ΔY−Gθ) and (ΔY−ΔX a Gv), and accordingly, the phase difference θ8 and the inverter voltage v1R are also changed by Δθ and Δv0, respectively. Therefore, Δθ and ΔV at this time are as shown in the following equations.

On the other hand, the phase difference θ and the inverter voltage v1 are Δθ,
The change ΔP in active power and the change ΔQ in reactive power when ΔvI changes can be expressed as follows.

If we perform each partial differentiation and arrange them, we get the following.

Therefore, vI =■IRl vL""vLR'θ=08
ΔP and ΔQ when the state color changes by Δθ, ΔV□
can be expressed as follows.

As can be seen from the above αη formula, in the case of this embodiment, multiple phases and voltages are simultaneously manipulated by the output signal change ΔX of the active power control calculator 15 using the active power control deviation as input, and as a result, the active power only changes. In addition, since the output signal change ΔY of the reactive power control calculator 16 using the reactive power control deviation as input is used to simultaneously manipulate the multiple phases and voltage, and as a result only the reactive power is changed, the active power control system and interference with the reactive power control system is eliminated.

This eliminates the need for the control calculation units 15 and 16 of each control system to reduce the control dyne and slow the response speed, which conventional inverters do to prevent the influence of interference. The number of control dynes and response speed can be increased freely within a range that takes into account the unique characteristics of each control loop, and the ability to follow changes in required active power and reactive power, as well as grid side voltage. It is possible to improve the corrective operation function for changes in active power and reactive power due to changes in power and phase. In addition, it becomes possible to effectively utilize the coordination characteristics of fuel cells.

In the above embodiment, the voltage correction thread number section 17 and the phase correction thread number section 18 are provided, and the phase and voltage of the output of the inverter 2 are controlled by the correction signals from both of them. For example, if the stability of only the supply of active power is required, only the phase correction thread count part 18 is used as shown in FIG. 2, and if the stability of only the supply of reactive power is required, As shown in FIG. 3, by using only the voltage correction thread number section 17, the control device can be simplified and costs can be reduced.

In addition, in the above embodiment, Gv and Gv are made variable gains in order to eliminate interference between the active power control system and the reactive power control system in the entire output range of the interface 2, but if a little interference is allowed, then For example, θ, V1. VL may be fixed to an approximate value.

It goes without saying that each of the sections shown in the above embodiments can be constructed either as a node or as software using a microprocessor or the like.

〔Effect of the invention〕

As described above, according to the present invention, the conventional inverter control method that controls the phase of active power and the voltage of reactive power is improved, and by adding a relatively simple mutual correction signal, active power can be controlled. Since interference between control and reactive power control is eliminated, it is possible to perform stable and coordinated inverter power control that meets system requirements. The advantages of the power source can be utilized more effectively, and a great effect can be obtained in improving the supply capacity and stability of the AC power system.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an inverter control device showing one embodiment of the invention, and FIGS. 2 and 3 are block diagrams of inverter control devices showing other embodiments of the invention. DESCRIPTION OF SYMBOLS 1... Fuel cell, 2... Inverter, 3... Power transmission line, 4... Power system, 5... Active power detector, 6
... Reactive power detector, 7... Phase detector, 8...
Voltage detector, 9 to 12... Comparator, 13... Active power setter, 14... Reactive power setter, 15... Active power control calculator, 16... Reactive power control calculator , 17
. . . Voltage correction coefficient section, 18 . . . Phase correction coefficient section, 1
9... Phase control calculation circuit, 20... Voltage control calculation circuit, 21... Waveform control circuit. Figure 1 2nd cause

Claims (3)

[Claims] (1) A control device for a self-excited power converter that converts the output of a DC power source into alternating current, comprising: an active power control section that issues a phase command signal for the output voltage of the self-excited power converter according to a control deviation of the active power; , a voltage correction coefficient unit that generates a voltage correction signal for the output of the self-excited power converter based on the phase command signal, and a reactive unit that generates a voltage command signal for the output of the self-excited power converter based on control deviation of reactive power. a power control section, a phase correction coefficient section that generates a phase correction signal for the output voltage of the self-excited power converter based on the voltage command signal, and performs multi-phase control based on the sum of the phase command signal and the phase correction signal. It has a phase control section and a voltage control section that controls stain pressure by the sum of a voltage command signal and a voltage correction signal, and the phase of the output of the self-excited power converter is controlled by the output signals of the phase control section and the voltage control section. A control device for a self-excited power converter, characterized in that it controls voltage. (2) In a control device for a self-excited power converter that converts the output of a DC power source into alternating current, an active power control section that issues a phase command signal for the output voltage of the self-excited power converter according to a control deviation of the active power; , a reactive power control unit that generates a voltage command signal for the output of the self-excited power converter based on a control deviation of the reactive power; and a reactive power control unit that generates a phase correction signal for the output voltage of the self-excited power converter based on the voltage command signal. a phase control section that performs phase control based on the sum of a phase command signal and a phase correction signal; and a voltage control section that performs stain pressure control based on the voltage command signal; A control device for a self-excited power converter, characterized in that the phase and voltage of the output of the self-excited voltage converter are controlled based on an output signal of a voltage control section. (3) In a control device for a self-excited power converter that converts the output of a DC power source into alternating current, an active power control section that issues a phase command signal for the output voltage of the self-excited power converter (based on a control deviation of active power); , a voltage correction coefficient section that generates a correction signal for the output voltage of the self-excited power converter based on the phase command signal; a reactive power control section that generates a reactive power; a control section that performs stain pressure control based on the sum of a voltage command signal and a voltage correction signal; and a phase control section that performs phase control based on a phase command signal; A control device for a self-excited power converter, characterized in that the phase and voltage of the output of the self-excited power converter are controlled by an output signal of a voltage control section.