JPH04367010A - Static reactive power generator - Google Patents

Abstract

PURPOSE:To obtain a static reactive power generator which improves transiently the response of the DC voltage control and the response of the reactive current control to the fluctuation of a reactive current. CONSTITUTION:A static reactive power generator is provided with a reactive current controller 14 which calculates a circulating angle reference signal, a DC voltage reference deciding circuit 12 which decides a DC voltage reference signal, a DC voltage controller 13 which calculates a phase difference reference signal, and a pulse width modulation control circuit 10 which controls each inverter based on the circulating angle reference signal, the phase difference reference signal, and the phase reference signal obtained by a 1st sensor. Furthermore a phase difference compensating circuit 16 is added to compensate the phase difference reference signal based on the reactive current feedback signals 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static reactive power generator for regulating reactive power in a grid.

0002

2. Description of the Related Art FIG. 3 shows a control circuit for a conventional static reactive power generator. 6 is a capacitor for adjusting reactive power, 6 is a PT for detecting system voltage, 7 is a CT for detecting system current, 8 is a sensor that detects the PWM phase reference φO, reactive current IQ, and active voltage VP from the system voltage and system current, and 9 is a sensor for detecting the PWM phase reference φO, reactive current IQ, and active voltage VP. capacitor 5
10 is a pulse width modulation (hereinafter referred to as PWM) circuit that controls the gate of the inverter 4; 11 is an A/D converter that converts an analog signal into a digital signal; 12 13 is a DC voltage reference determination circuit that determines the DC voltage reference signal Vd* from the grid effective voltage VP; 13 is the DC voltage reference signal Vd*
14 is a reactive current controller that controls reactive current; 15 is a DC voltage controller that calculates a phase difference reference signal Δφ between the system voltage and the output voltage of the static reactive power generator from the DC feedback signal Vd − and controls the DC voltage; indicates a digital circuit section.

[0003] The operation related to the above configuration will be explained. First, the basic principle of a static reactive power generator will be described. Output voltage of static reactive power generator (each inverter 4
When the magnitude, frequency, and phase of the output voltage of If the output voltage of the device is controlled to be higher than the grid voltage, a phase-advanced current will flow into the static reactive power generator, and conversely, if the output voltage of the static reactive power generator is lower than the grid voltage, static reactive power will be generated. A slow phase current flows into the device. In order to control reactive power, it is sufficient to control the output voltage of a static reactive power generator, but generally this is done by variably adjusting the DC voltage of the capacitor while keeping the inverter's conduction angle θ constant. There is a PAM method that controls the inverter output voltage, and a PWM method that controls the inverter output voltage value by keeping the DC voltage of the capacitor constant and variably adjusting the inverter conduction angle θ. This is a PWM method. Further, the DC voltage is controlled by the phase difference between the grid voltage and the output voltage of the static reactive power generator, and the output voltage of the static reactive power generator is controlled by the inverter current angle θ.

[0004] Here, the inverter output voltage is expressed by the following equation. VOI=4/(√2・π)・Ed・SIN(θ/2
) (1) θ: Inverter conduction angle Ed: DC voltage VOI: Fundamental wave effective value of inverter output voltage Also, the DC voltage is determined by the DC voltage controller 13 from a constant DC voltage reference signal Vd* and DC voltage feedback signal Vd-. It is controlled by the phase difference reference signal Δφ calculated by.

Next, regarding reactive power control, the reactive current controller 14 controls the conduction angle reference signal θ based on the reactive current reference signal IQ* and the reactive current feedback signal IQ-.
* is calculated, and this conduction angle reference signal θ* is applied to the PWM circuit 10, which determines the gate pulse of each single-phase inverter 4, and applies it to each single-phase inverter 4. The multiplex transformer 3 synthesizes the output voltages of the single-phase inverters and generates the output voltage V of the static reactive power generator.
Generate I. Reactive power is generated via the reactor 2 due to the generated differential voltage between the output voltage VI of the static reactive power generator and the system voltage VS.

As described above, in a steady state, when the grid voltage increases, the conduction angle θ becomes larger in order to generate the corresponding output voltage of the static reactive power generator. , (1), the voltage is not generated as much as the flow angle θ changes. Therefore, the DC voltage is increased by the DC voltage reference determination circuit 12, which increases the DC voltage reference in accordance with the grid voltage, to generate the output voltage of the static reactive power generator corresponding to the grid voltage.

[0007]

[Problem to be Solved by the Invention] Since the conventional static reactive power generator is configured as described above, it becomes 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 in response to the transient response of the current, and the response of reactive current control deteriorates. In addition, in order to reduce the mutual interference, there is a problem in that the response of the reactive current must be adjusted to be smaller than the response of the DC voltage control.

The present invention has been made in order to solve the above-mentioned problems, and is a static control system that transiently improves the response of DC voltage control to fluctuations in reactive current and improves the response of reactive current control. The present invention provides a reactive power generation device.

[0009]

SUMMARY OF THE INVENTION A static reactive power generator device according to the present invention is configured to include a circuit that compensates a phase difference reference signal for reactive current.

0010

[Operation] In 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 DC voltage fluctuation caused by the reactive current response. , the response of reactive current control is improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a static reactive power generator according to this embodiment. In the figure, the same symbols as in FIG. 3 indicate the same parts, and 16 calculates phase difference compensation for the reactive current feedback signal IQ-. The phase difference compensation circuit is composed of proportional and incomplete differential elements, and the output phase difference compensation signal is determined so that it has a lagging phase with respect to the system voltage when the reactive current is leading in phase.

In the configuration shown in FIG. 1, the portion of the prior art explained in FIG. 3 operates in the same manner, so it will be omitted, and the operation of the phase difference compensation circuit 16 for reactive current according to the present embodiment will be explained. This will be explained with reference to the transient characteristics of each feedback signal of the reactive current response shown in FIG. First, the operation without the phase difference compensation circuit 16 shown in FIG. 2 will be described. In response to the step response of the reactive current reference signal IQ*, the conduction angle reference signal θ* output from the DC voltage reference determining circuit 14 changes in a stepwise manner, and based on this, the PWM circuit 10 determines the gate pulse. Each single-phase inverter 4 is controlled. As a result, the output of the A/D converter 11 that A/D converts the output of the sensor 9 that detects the DC voltage of the capacitor 5, that is, the DC voltage feedback Vd- fluctuates. In order to control this constant, the DC voltage control by the controller 13 operates to operate the phase difference reference Δφ. During this period in which the DC voltage fluctuates, the reactive current feedback signal IQ- rises slowly.

Next, if a phase difference compensation circuit 16 is inserted at this time, it will become as shown by the dotted line in FIG. The response is compensated, the DC voltage fluctuation period is shortened, and the rise of the reactive current feedback signal IQ- 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 that controls the DC voltage fluctuation caused by the reactive power to be constant can be improved. Transient compensation has the effect of improving reactive power response.

[Brief explanation of drawings]

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

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

FIG. 3 shows a conventional static reactive power generator device.

[Explanation of symbols]

1　　　　　　System voltage 2 Reactor 3 Multiplex 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)

[Claims] Claim 1: A multiplex transformer connected to a power system via a reactor, a multiplex connected single-phase inverter device, a capacitor for adjusting reactive power, and a reactive current, a system active voltage, and a system voltage from a system voltage and a system current. A first sensor detects a phase reference signal for synchronization, a second sensor detects a DC voltage, and controls a reactive current based on a reactive current feedback signal from the first sensor and a reactive current reference signal provided. a reactive current controller that calculates a current conduction angle reference signal, a DC voltage reference determination circuit that determines a DC voltage reference signal from the system effective voltage from the first sensor, and a DC voltage feedback signal from the second sensor and the A DC voltage controller that calculates a phase difference reference signal to control the DC voltage based on the DC voltage reference signal, and each of the inverters based on the conduction angle reference signal, the phase difference reference signal, and the phase reference signal from the first sensor. A stationary reactive power generator comprising a pulse width modulation control circuit for controlling switching of the stationary reactive power generator, comprising a phase difference compensation circuit for compensating the phase difference reference signal based on the reactive current feedback signal. Type reactive power generator.