JP2000270479A - Operation control method for reactive power compensator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of most effective operation for a reactive power compensator which is combined with a load, where the actions at start and at operation differ greatly, such as in a wind-turbin generator. SOLUTION: A current sensor 5 is connected to a reactive power compensator 4, and the reactive power compensator 4 is operated only when the load current flowing toward a load 3 exceeds the threshold, and after the load 3 starts power generation, the reactive power compensator 4 is stopped. what is more, it is desirable to decide the set value according to the detected system voltage, when starting the reactive power compensator 4. Then, at forward sending when the current flows toward the load 3, the reactive power compensator 4 is made to perform power factor 1 control, and at reverse sending when the current is sent from the load 3 to a substation 1, it is made to perform voltage constant control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control method for a reactive power compensator, and more particularly, to an operation control for a reactive power compensator installed in combination with a distributed power source such as a wind power generator. It is about the method.

[0002]

2. Description of the Related Art Reactive power compensator (SVG: static var)
generator), as shown in FIG. 1, is a capacitor and an inverter circuit connected in parallel to a system via an interconnection reactor. The output voltage of the inverter circuit is synchronized with the phase of the system voltage to change the magnitude. Accordingly, a current leading or lagging from the system voltage can be supplied to the interconnection reactor to adjust the voltage. As the operation control method of the reactive power compensator, there are known a constant voltage control for maintaining the system voltage at a set value and a power factor 1 control for reducing the reactive power to zero.

[0003] Such a reactive power compensator is used to stabilize system voltage when a ski lift or a crusher at a quarry is installed at the end of a long distribution line. Used. In such a conventional case, the reactive power compensator is usually operated at all times. However, recently, distributed power sources represented by wind power generation have become widespread, and in that case, handling different from a conventional simple load has been required.

[0004] That is, a distributed power source such as a wind power generator is usually provided in a remote place from a substation such as a mountaintop or a shore. In particular, a wind power generator consumes a large amount of electric power as an induction motor at startup. For this reason, in order to prevent the starting from being impossible due to a sudden voltage drop of the distribution line, a reactive power compensator is connected in the vicinity thereof to prevent the voltage drop. However, the wind power generator consumes electric power at the time of start-up, but generates electric power when the operation is started. For this reason, the prevention of voltage drop by the reactive power compensator is required for a very short time, and it is considered useless to operate the reactive power compensator constantly. The reactive power compensator can be used to suppress the rise of the system voltage even after the wind generator starts generating power, but it is irrational to perform the same operation control because the behavior of the load is completely different. It is considered to be.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a reactive power compensator combined with a load such as a wind power generator whose behavior at the time of start-up and operation is greatly different. The purpose of the present invention is to provide a method of controlling the operation of a reactive power compensating device for driving a vehicle.

[0006]

According to a first aspect of the present invention, a load current signal from a current sensor is input to a reactive power compensator connected near a load. The reactive power compensator is operated only when the value exceeds a threshold. In this case, when activating the reactive power compensator, the system voltage is first detected, the set value is determined according to the detected system voltage, and the constant voltage control is performed so as to maintain the set value. Is preferred. The second invention causes a reactive power compensator connected near a load having a power generation function to perform power factor 1 control during forward feeding of current toward the load, and to perform constant voltage control during reverse feeding. It is characterized in that it is performed.

[0007] According to the first aspect, it is possible to eliminate waste of constantly operating the reactive power compensator. Further, according to the second aspect, optimal control in accordance with the behavior of a load having a power generation function can be performed. Hereinafter, preferred embodiments of each invention will be described.

[0008]

(Embodiment of the first aspect of the present invention) FIG. 2
, 1 is a substation, 2 is a transmission line, and 3 is a load. The load 3 is a wind power generator, which is one of the distributed power sources, and requires power as an induction motor at the time of startup as described above, but has a capability of transmitting the generated power to the substation 1 during operation. is there. Reference numeral 4 denotes a reactive power compensator (SVG) installed near the load 3, which is connected in parallel to the transmission line 2 as shown in FIG.

The reactive power compensating device 4 includes a current sensor 5 for detecting a load current flowing through the transmission line 2, and a detected load current signal is input to a control device of the reactive power compensating device 4. Then, the reactive power compensator 4 is operated only when the load current flowing through the transmission line 2 toward the load 3 exceeds the threshold value.

[0010] For this reason, when starting the load 3 which is a wind power generator, a large load current flows, so that the reactive power compensator 4 is operated to prevent the system voltage from lowering. Even when the wind turbine is operating, the reactive power compensator continues to operate if the current exceeds the threshold. However, when the operation of the wind power generator is stopped, the load current falls below the threshold, so that the operation of the reactive power compensator 4 is automatically stopped. Therefore, according to the present invention, there is an advantage that the waste of constantly operating the reactive power compensator 4 even when it is unnecessary is eliminated, and the power consumption by the reactive power compensator 4 is suppressed.

When the rated voltage of the system is 6600 V, the reactive power compensator 4
V, 6450 V, 6600 V, and 6750 V, and it is common to perform constant voltage control so that the set value is obtained.
In the invention of claim 1, the reactive power compensator 4 may be operated in such a manner. However, when the actual system voltage deviates greatly from the above-mentioned voltage, there is a possibility that a steep voltage fluctuation may occur when the reactive power compensator 4 is started. Further, if the reactive power compensating device 4 exhibits the full capability to return the voltage to the set value, if there is a steep voltage change in the middle of the reactive power compensating device 4, there is no longer a sufficient capacity, and there is a possibility that the voltage change cannot be handled. .

Therefore, according to the second aspect of the present invention, when starting the reactive power compensator 4, the system voltage is first detected, the set value is determined according to the detected system voltage, and the set value is maintained. Voltage constant control is performed as described above. FIG. 3 shows a specific control flow for carrying out the invention of claim 2.

That is, even when a signal to start up is input to the reactive power compensating device 4 according to the first aspect of the present invention, full operation is not immediately performed, but first, the reactive power compensating device 4 uses a part of its capability. The system voltage is sampled while a certain 150 kVar is output. Then, a value closest to the sample value is determined as a set value from the above four types of voltage values, and voltage constant control is performed. If the set value is determined in consideration of the system voltage and the constant voltage control is performed, no steep voltage fluctuation occurs when the reactive power compensating device 4 is started, and the reactive power compensating device 4 has an extra power. Can be started in a state where is left.

(Embodiment of the Invention of Claim 3) FIG. 4 is a diagram showing an embodiment of the invention of claim 3, wherein 1 is a substation, 2
Is a transmission line, and 3 is a load such as a wind power generator having a power generation function. The reactive power compensator 4 connected near the load 3 includes a current sensor 5 and a voltage sensor 6, and detects the current direction of the transmission line 3 from the phase difference between the current and the voltage. When the current flows toward the load 3 sequentially, the reactive power compensator 4 performs the power factor 1 control.
In the case of reverse transmission in which power is transmitted toward, voltage constant control is performed.

According to the present invention, when the wind power generator or the like is started, the load 3 becomes an L load and a voltage fluctuation occurs. However, the reactive power compensator 4 performs the power factor 1 control that can provide a high-speed response. Thus, the voltage fluctuation can be quickly compensated. After the load 3 starts generating power, the control is switched to the constant voltage control in order to suppress the voltage rise of the entire system. As described above, the invention of claim 3 is different in that the reactive power compensator 4 is operated even after the load 3 starts generating power. However, the reactive power is optimally adjusted in accordance with the operation state of the load 3 having the power generating function. This is common in that operation control of the compensating device 4 is performed.

In each of the inventions, the load 3 has a power generation function, but is not necessarily limited to the wind power generator as in the embodiment, and is not limited to a garbage power generation, a small hydropower generation, a cogeneration power generation. And various kinds of distributed power sources that require electric power to start a sodium-sulfur battery or the like.

[0017]

As described above, according to the first aspect of the present invention, the reactive power compensator is operated only when necessary,
By stopping the system when it is not necessary, it is possible to eliminate waste of constantly operating the reactive power compensator. Further, according to the third aspect of the invention, it is possible to quickly respond to a steep voltage change at the time of starting the load, and it is possible to effectively suppress a voltage rise of the entire system after the start.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a reactive power compensator.

FIG. 2 is a circuit diagram showing an embodiment of the present invention.

FIG. 3 is a specific control flow chart for implementing the invention of claim 2;

FIG. 4 is a circuit diagram showing an embodiment of the third invention.

[Explanation of symbols]

1 substation, 2 distribution line, 3 load, 4 reactive power compensator, 5 current sensor, 6 voltage sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuomi Toyoda 1 Kamikobari, Inuyama City, Aichi Prefecture Energy Support Co., Ltd. F-term (reference) 5G066 FA01 FB13 FC11 5H420 BB16 CC04 DD03 DD06 EA27 EB39 FF03 FF04 FF26

Claims (4)

[Claims] A load current signal from a current sensor is input to a reactive power compensator connected near a load, and the reactive power compensator is operated only when the load current exceeds a threshold value. An operation control method for the reactive power compensator. 2. When activating a reactive power compensator, a system voltage is first detected, a set value is determined according to the detected system voltage, and a constant voltage control is performed so as to maintain the set value. The operation control method for a reactive power compensator according to claim 1. 3. A reactive power compensator connected near a load having a power generation function performs power factor 1 control during forward feeding of current toward the load, and performs constant voltage control during reverse feeding. An operation control method for a reactive power compensator, comprising: 4. The operation control method for a reactive power compensator according to claim 1, wherein the load is a distributed power source that consumes power at startup.