JP3032046B2 - Static reactive power generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static var generator for adjusting reactive power of a system.

[0002]

2. Description of the Related Art FIG. 3 shows a control circuit of a conventional static var generator, in which 1 is a system voltage, 2 is a reactor, 3 is a multiplex transformer, 4 is a single-phase inverter connected in multiple stages, 5 reactive power adjustment capacitor, the sensor 6 is the system voltage detection PT, 7 line current detecting CT, 8 is for detecting the system voltage, PWM phase reference from the system current phi _O and reactive current I _Q and the effective voltage V _P , 9 is a sensor for detecting the DC voltage of the capacitor 5, 10 is a pulse width modulation (hereinafter, PWM is referred to as pulse width modulation) circuit for controlling the gate of the inverter 4, and 11 is an A / A which converts an analog signal into a digital signal. D converter, 12 is a DC voltage reference determining circuit for determining the grid effective voltage V _P from the DC voltage reference signal V _d ^*, 13 is a DC voltage reference signal V _d ^* and the DC feedback signal V _d ^- from the system voltage and electrostatic A DC voltage controller that calculates a phase difference reference signal Δφ of the output voltage of the static power generation device and controls the DC voltage, 14 is a reactive current controller that controls the reactive current, and 15 is a digital circuit unit.

The operation of the above configuration will be described. First, the basic principle of the static var generator will be described. When the magnitude, frequency, and phase of the output voltage of the static var generator (the output voltage of each inverter 4 synthesized by the multiplex transformer 3) are synchronized with the system voltage, the static var generator flows from the system to the static var generator. Current is zero,
When the output voltage of the static var generator is controlled to be higher than the system voltage, a leading current flows into the static var generator, and conversely, when the output voltage of the static var generator is lower than the grid, A late-phase current flows into the static reactive power generator. In order to control the reactive power, it suffices to control the output voltage of the static var generator, but in general,
The PAM method controls the output voltage of the inverter by variably adjusting the DC voltage of the capacitor while keeping the conduction angle θ of the inverter constant. There is a PWM method for variably adjusting the output voltage value of the inverter, and FIG. 3 shows the latter PWM method. The DC voltage is controlled by the phase difference between the system voltage and the output voltage of the static var generator, and the output voltage of the static var generator is controlled by the inverter conduction angle θ.

Here, the inverter output voltage is expressed by the following equation. V _OI = 4 / (√2 · π) · Ed · SIN (θ / 2) (1) θ: inverter conduction angle Ed: DC voltage V _OI : fundamental wave effective value of inverter output voltage is controlled by more calculated by the DC voltage controller 13 a phase difference reference signal △ phi ^- constant DC voltage reference signal V _d ^* and the DC voltage feedback signal V _d.

[0005] Next, we describe the reactive power control, reactive current reference signal I _Q ^* and reactive current feedback signal I _Q ^- by reactive current controller 14 based on, conduction angle reference signal theta ^* is calculated, the flowing The angle reference signal θ ^* is supplied to the PWM circuit 10, the gate pulse of each single-phase inverter 4 is determined by the PWM circuit 10, and supplied to each single-phase inverter 4. Multiple transformer 3 generates an output voltage V _I of the synthesized static var generator the output voltage of the single-phase inverter. Output voltage V _{I of the} generated static reactive power generator
Reactive power is generated via the reactor 2 by the difference voltage between the power supply voltage and the system voltage V _S.

[0006] As described above in a steady state, when the system voltage rises, the conduction angle θ increases in order to generate a corresponding output voltage of the static type reactive power generator. , (1), no voltage is generated as much as the flow angle θ changes. Therefore, the DC voltage is increased by the DC voltage reference determination circuit 12 that increases the DC voltage reference according to the system voltage, and the output voltage of the static var generator corresponding to the system voltage is generated.

[0007]

Since the conventional static type reactive power generator is constructed as described above, it is ineffective due to mutual interference between the phase difference control of DC voltage control and the inverter conduction angle control of reactive current control. The DC voltage fluctuates with respect to the transient response of the current, and the response of the reactive current control deteriorates. In addition, there is another problem that the response of the reactive current must be adjusted to be smaller than the response of the DC voltage control in order to reduce the mutual interference.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a stationary device for transiently improving the response of DC voltage control and improving the response of reactive current control in response to a change in reactive current. And a reactive power generator.

[0009]

According to the present invention, there is provided a static var generator in which a circuit for compensating a phase difference reference signal with respect to a reactive current is provided.

[0010]

According to the present invention, the phase difference reference compensation circuit improves the response of the DC voltage control system by compensating the phase difference reference for the reactive current with respect to the DC voltage fluctuation caused by the reactive current response. In addition, the response of the reactive current control is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows a block diagram of a static var generator device according to this example, in the figure, there in FIG. 3 the same reference numerals identical parts, 16 the reactive current feedback signal I _Q ^- calculating a phase difference compensation with respect to The phase difference compensating circuit includes a proportional / incomplete differential element and the like, and the output phase difference compensating signal is determined so as to have a phase lag with respect to the system voltage in the case of a leading reactive current.

In the configuration shown in FIG. 1, the portion of the prior art described with reference to FIG. 3 operates in a similar manner, and thus is omitted, and the operation of the portion of the phase difference compensating circuit 16 for the reactive current according to the present embodiment is illustrated. This will be described with reference to the transient characteristics of each feedback signal of the reactive current response shown in FIG. First, the operation when the phase difference compensating circuit 16 shown in FIG. 2 is not provided will be described. In response to the step response of the reactive current reference signal I _Q ^*, the conduction angle reference signal θ ^* output from the DC voltage reference determination circuit 14 changes stepwise, and based on this, the PWM circuit 10 determines the gate pulse. Then, each single-phase inverter 4 is controlled. As a result, the output of the A / D converter 11 which outputs the A / D conversion of the sensor 9 for detecting the DC voltage of the capacitor 5, i.e. the DC voltage feedback V _d ^- varies. The DC voltage control by the controller 13 operates to control the phase difference constant, and the phase difference reference △ φ operates. The period in which the DC voltage fluctuates reactive current feedback signal I _Q ^- rising is delayed.

[0013] Then, at this time, when I'll put the phase difference compensation circuit 16 will be as a dotted line shown in FIG. 2, the reactive current feedback signal I _Q ^- so to compensate for the phase difference with respect to the conventional DC voltage control to compensate for the response DC voltage fluctuation period is shortened, the reactive current feedback signal I _Q ^- rise is improved.

[0014]

As described above, according to the present invention, since the phase difference reference is compensated for the reactive current, the response of the DC voltage for controlling the DC voltage fluctuation caused by the reactive power to be constant is improved. Transient compensation has the effect of improving the response of reactive power.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating an operation of a transient characteristic by a phase difference reference compensation circuit used in the present invention.

FIG. 3 shows a prior art static var generator device.

[Explanation of symbols]

 1 System Voltage 2 Reactor 3 Multiple Transformer 4 Single-Phase Inverter 5 Capacitor 6 PT 7 CT 8 Sensor 9 Sensor 10 PWM Circuit 11 A / D Converter 12 DC Voltage Reference Determination Circuit 13 DC Voltage Controller 14 Reactive Current Controller 16 Phase Difference Reference Compensation circuit

Claims (1)

(57) [Claims] 1. A multiplexing transformer connected to a power system via a reactor, a single-phase inverter device multiplexedly connected, a reactive power adjusting capacitor, a reactive current from a system voltage and a system current, a system active voltage, and A first sensor for detecting a phase reference signal for synchronization, a second sensor for detecting a DC voltage, and controlling a reactive current based on a reactive current feedback signal provided by the first sensor and a reactive current reference signal given thereto. A reactive current controller for calculating a conduction angle reference signal, a DC voltage reference determination circuit for determining a DC voltage reference signal from a system effective voltage by the first sensor, a DC voltage feedback signal from the second sensor, A DC voltage controller that calculates a phase difference reference signal to control the DC voltage based on the DC voltage reference signal; and the conduction angle reference signal, the phase difference reference signal, A pulse width modulation control circuit for controlling the switching of each of the inverters based on the phase reference signal from the first sensor, wherein the phase difference reference signal is compensated based on the reactive current feedback signal. And a phase difference compensating circuit.