JPH0654545A - Controller of inverter - Google Patents

Abstract

PURPOSE:To obtain an inverter controller which is not influenced by the fluctuation of a system voltage in order to control the active power and reactive power of the inverter linked in a system with control of the output current of the inverter. CONSTITUTION:A voltage detector 6 which detects a system voltage, a voltage fluctuation correcting circuit 19 which outputs a signal for correction of the fluctuation of the system voltage in accordance with the value detected by the voltage detector 6 and a current instruction calculting circuit 12 to which an active power instruction form an active power setting circuit 9, a reactive power instruction from a reactive power setting circuit 10, a sine wave signal from a sine wave generator 11 and a voltage fluctuation correction signal from a voltage fluctuation correction circuit 19 are inputted are provided. With this constitution, in order to calculate a current instruction, an inverter current can be controlled with a high accuracy by using the signal for the correction of the fluctuation of the system voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an inverter connected to a power system.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing, for example, a conventional controller for an inverter for grid interconnection, which is shown in a collection of lectures of the 1st Annual Meeting of the Institute of Electrical Engineers of Japan in 1991. In the figure, 1 is a switch connected to the power system, 2 is an AC reactor connected to the switch 1, 3 is a filter capacitor connected to the system side of the AC reactor 2, and 4 is connected to the AC reactor. Inverters 5 are DC power supplies for the inverter 4.

Further, 6 is a voltage detector for detecting the output voltage of the inverter 4, 7 is a voltage setting device for setting an output voltage command value of the inverter 4, 8 is an output voltage control circuit of the inverter 4, and 9 is an active power command. A setting circuit, 10 is a reactive power command setting circuit, 11 is a sine wave generation circuit, 12 is a current whose input is the output of the active power command setting circuit 9 and the output of the reactive power command setting circuit 10 and the output of the sine wave generation circuit 11. It is an arithmetic circuit.

Further, 13 is a current detector for detecting the output current of the inverter 4, 14 is a switch for switching between the independent operation mode and the interconnection operation mode, and 15 is the current detector 13.
Current control circuit for inputting the output of the voltage control circuit 8 or the current calculation circuit 12 via the switch, 16 for inputting the carrier signal generating circuit, and 17 for inputting the output of the current control circuit 15 and carrier signal generating circuit 16. The PWM control circuit, 18 is a gate drive circuit that drives the switching element of the inverter 4 by the output of the PWM control circuit 17.

Next, the operation will be described. During the interconnection operation, the switch 1 is closed and the switch 14 is closed on the interconnection side, and the output signal of the sine wave generating circuit 11, the active power command from the active power setting circuit 9 and the reactive power setting circuit 10 are disabled. The current value calculated by the current calculation circuit 12 using the power command is given to the current control circuit 15 as an inverter output current command value.

In the current control circuit 15, a control signal for controlling the output current of the inverter 4 detected by the current detector 13 to match the current command value from the current calculation circuit 12 is PW.
It is output to the M control circuit 17. The PWM control circuit 17 outputs the switching signal of the element to the gate drive circuit 18 based on the comparison between the output signal of the current control circuit 15 and the carrier signal from the carrier signal generation circuit 16. The gate drive circuit 18 supplies drive power to the switching element based on the switching signal. In this way, the output active power and reactive power of the inverter 4 are controlled to predetermined values by controlling the output current of the inverter 4.

[0007]

The conventional inverter control device is constructed as described above, and since the active power and the reactive power are controlled only by controlling the output current of the inverter 4, the system voltage fluctuates. In that case, there is a problem that the active power and the reactive power output from the inverter 4 vary.

The present invention has been made to solve the above problems, and controls an inverter capable of controlling active power and reactive power output from the inverter even if the system voltage fluctuates. The purpose is to obtain the device.

[0009]

According to a first aspect of the present invention, there is provided an inverter control device which controls an output current of an inverter connected to a power system on the basis of a current command value. In an inverter control device for controlling electric power and reactive power, voltage detection means for detecting the system voltage of the power system, and a correction value for the current command value to correct the fluctuation of the system voltage based on the system voltage detection value. And a correction means to be added.

The control device for an inverter according to a second aspect of the present invention outputs from the inverter by controlling to a current command value based on the output current of the inverter connected to the power system via the AC reactor and the filter capacitor. In an inverter control device for controlling active power and reactive power, voltage detection means for detecting the system voltage of the power system, and a correction value for the current command value to correct the fluctuation of the system voltage based on the system voltage detection value. Correction means for adding, current detection means for detecting the current flowing through the power system through the AC reactor and the filter capacitor,
The current control means obtains a new current command value based on the deviation between the output of the current detection means and the current command value corrected by the correction means.

[0011]

The inverter control device according to the first aspect of the present invention detects the fluctuation of the system voltage and corrects the current command value to thereby reduce the influence of the fluctuation of the system voltage in the control of the inverter active power and reactive power. Without it, the active power and the reactive power output from the inverter are controlled to be constant.

Further, an inverter control device according to a second aspect of the invention detects a current flowing from the inverter to the power system through the AC reactor and the filter capacitor, and detects the detected current and the current command value obtained according to the first aspect. By controlling the output current based on the deviation, the active power and the neglected power are controlled to be constant while ignoring the influence of the AC reactor and the filter capacitor.

[0013]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG. 1, 1 to 18 are the same parts as those in FIG. 3 described above. Reference numeral 19 is a voltage fluctuation correction circuit that corrects the influence of fluctuations in the system voltage based on the signal from the voltage detector 6 that detects the system voltage, and 20 is the detected value of the current detector 13 that detects the output current of the inverter 4 and the switch Is an adder circuit for obtaining the deviation from the output signal of the current command calculation circuit 12 given via
Given to.

Next, the operation will be described. During the interconnection operation, with the switch 1 turned on and the switch 14 closed to the interconnection side, the current control circuit 15 responds to the current command value from the current command calculation circuit 12 input via the switch 14. A current command for controlling the output currents of the inverters 4 to match is sent. That is, in this interconnection operation, the current command becomes an output signal of the current command calculation circuit 12 because the switch 14 is closed on the interconnection side. This output signal is calculated as follows.

A current command calculation circuit 12 outputs a current command to be output by the inverter 4 according to the active power command from the active power setting circuit 9, the reactive power command from the reactive power setting circuit 10 and the sine wave signal from the sine wave generation circuit 11. Calculate with. Moreover, at this time, if the system voltage is constant, the conversion from the power command to the current command is performed without causing an error.

However, when the system voltage changes, even if the inverter 4 outputs a current that matches the current command calculated from the power command, the actual power and the neglected power actually output from the inverter 4 are different from each other. Since it is different from the power command, the current command calculation circuit 12 uses the signal from the voltage fluctuation correction circuit 19 that receives the output signal of the system voltage detector 6 and corrects the fluctuation of the power output due to the fluctuation of the system voltage. The current command is corrected and output to the switch 14.

The current command signal output to the switch 14 is given to the adder circuit 20, and the adder circuit 20 obtains the deviation from the current detector 13. This deviation is caused by the current control circuit 1
5 and is controlled to be zero, and its control output is supplied to the PWM control circuit 17. PWM control circuit 1
A switching signal of the inverter element is supplied from 7 to the gate drive circuit 18, and the inverter 4 is switching-controlled based on the switching signal.

Example 2. In the first embodiment described above, the case where the active power and the reactive power of the inverter 4 are controlled by the output current control of the inverter 4 has been described. However, as shown in FIG. 2, the current detector 13, the AC reactor 2, A current detector 21 for detecting a current output to the system via the filter capacitor 3 and the switch 1, an adder 22 for obtaining a deviation between the output of the current detector 21 and the current command from the current command calculation circuit 12, Alternatively, a configuration may be adopted in which a current control circuit 23 is provided which receives the deviation signal as an input and controls so that the current command and the output current value match.

According to this structure, the active power and the reactive power are controlled by controlling the current output from the inverter 4. Therefore, the AC reactor 2 and the filter inserted between the inverter 4 and the grid are connected. Capacitor 3
Thus, the influence on the control of active power and reactive power can be completely eliminated, and by combining with the voltage fluctuation correction circuit 19, active power and reactive power can be controlled with higher accuracy.

[0020]

As described above, according to the first aspect of the present invention, the active power and the reactive power are controlled by the current control to correct the fluctuation of the system voltage, which is relatively simple. A highly accurate active power and reactive power control device can be obtained.

According to the second aspect of the present invention, the active power and the reactive power are controlled by controlling the output current output from the inverter to the power system via the AC reactor and the filter capacitor. The influence of the reactor and the filter capacitor can be ignored, and an inverter control device capable of controlling active power and reactive power with higher accuracy can be obtained.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a conventional inverter control device.

[Explanation of symbols]

 2 AC reactor 3 Filter capacitor 4 Inverter 6 Voltage detector 9 Active power setting circuit 10 Reactive power setting circuit 11 Sine wave generation circuit 12 Current command calculation circuit 13 Current detector 15 Current control circuit 19 Voltage fluctuation correction circuit 20 Addition circuit 21 Current Detector 22 Adder 23 Current control circuit

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[Procedure amendment]

[Submission date] November 2, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

According to this structure, the AC is supplied from the inverter 4.
Power system via reactor 2 and filter capacitor 3
Since the active power and the reactive power are controlled by controlling the current output to the inverter, the active power and the reactive power are controlled by the AC reactor 2 and the filter capacitor 3 inserted between the inverter 4 and the grid. Can completely eliminate the influence on the voltage fluctuation correction circuit 1
By combining with 9, it is possible to control active power and reactive power with higher accuracy.

Claims (2)

[Claims] 1. An inverter control device for controlling active power and reactive power output from an inverter by controlling an output current of an inverter connected to the power system based on a current command value. An inverter control device comprising: a voltage detection unit that detects a voltage; and a correction unit that adds a correction value to the current command value to correct the fluctuation of the system voltage based on the system voltage detection value. 2. An inverter control for controlling active power and reactive power output from the inverter by controlling an output current of the inverter connected to the power system via an AC reactor and a filter capacitor based on a current command value. In the device, voltage detection means for detecting the system voltage of the power system, correction means for adding a correction value to the current command value to correct the fluctuation of the system voltage based on the detected value of the system voltage, the AC reactor and the filter. Current detecting means for detecting a current flowing through the power system via a capacitor, and current control means for obtaining a new current command value based on the deviation between the output of the current detecting means and the current command value corrected by the correcting means. An inverter control device comprising: