JPH04168921A - Reactive power compensator - Google Patents

Abstract

PURPOSE:To prevent the system voltage from hunting even upon variation of the system capacity by manually switching control through a circuit having low integration gain to control through a circuit having high integration gain. CONSTITUTION:A reactive power compensator comprises a circuit 7-2 having high integration gain, a circuit 7-3 having low integration gain, a circuit 10 for detecting hunting of system voltage, and a circuit 12-2 for switching from control through the circuit 7-2 to control through the circuit 7-3 in response to the hunting circuit, where a circuit 12-1 for switching from control through the circuit 7-3 to control through the circuit 7-2 comprises a manual reset circuit 13. According to the constitution, high response can be expected for the reactive power compensator under normal system condition and the system voltage is prevented from hunting through the reactive power compensator upon occurrence of system fault.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Field of Industrial Application) The present invention feeds back the grid voltage in order to stabilize the grid voltage, and adjusts the reactive power of the grid according to the deviation from the grid voltage reference. The present invention relates to a controlled reactive power compensator.

(Prior Art) A conventional reactive power compensator (hereinafter referred to as SvC) will be described using FIG. 2.

In Figure 2, 1 is a reactor, 2-1°2-2 is a thyristor, and reactor 1 and thyristor 2-1.2-2
A combination of these is usually called a cyrisk control reactor (hereinafter referred to as TCR), and is a type of SVC.

This also connects the current flowing to the accelerator L to the thyristor 2-1.
By controlling in 2-2, the system voltage can be controlled.

Next, an SvC control circuit that performs feedback control of the system voltage will be described. 3 is PT.

Reference numeral 4 denotes a voltage detection circuit, and the system voltage ■ is detected by the voltage detection circuit 4 through PT3. In order to maintain this system voltage V at the reference voltage Vref, a subtraction circuit 6 detects a difference voltage between Vref indicated by the reference voltage setting circuit 5 and the system voltage V, that is, an error voltage ΔV.

Next, in order to maintain the system voltage V at the reference voltage Vref, it is sufficient to make the error voltage Δ■ zero, so an integrating circuit 7-1 having ΔV as an input is provided.

The reactive power Q output from the integrating circuit 7-1 is
If R occurs, ΔV becomes zero. The phase control circuit 8 determines the firing angle α of the thyristors 2-1 and 2-2 for the TCR to generate the reactive power Q. 9 is thyristor 2
-1.2-2 is a gate pulse circuit that provides a gate pulse with a firing angle α, and as a result, the TCR generates reactive power Q, and as a result, ΔV becomes zero and the system voltage ■ is the reference voltage V
The grid voltage is stabilized by being maintained at ref.

(Problem to be Solved by the Invention J!i) What is desirable in the above feedback control is that even if the system voltage V deviates from the reference voltage Vref due to a disturbance, it can quickly return to Vref by the feedback control. For this purpose, it is preferable that the integral gain of the integrating circuit be large. However, if the integral gain is too large and the SVC capacity is larger than the system capacity, the system voltage will begin to hunt and become unstable. Therefore, the integral gain is usually set to a value as large as possible, but not so large as to cause hunting.

However, the system capacity is not always constant, and the system capacity may become significantly smaller than normal due to the operational status of the system or a system accident. In such a case, the integral gain mentioned earlier will no longer be an appropriate amount, and S
The reactive power compensation of vC may become excessive compensation for the grid, and the grid voltage may start hunting.

An object of the present invention is to provide a reactive power compensator that prevents grid voltage from hunting even if the grid capacity changes.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above-mentioned object, the present invention feeds back the grid voltage in order to stabilize the grid voltage, and calculates the deviation between the grid voltage reference and the grid voltage. In the reactive power compensation measure that controls the reactive power of the grid according to It is characterized by a switching circuit that switches from control by a circuit with a large integral gain to control by a circuit with a small integral gain, and switching from control by a circuit with a small integral gain to control by a circuit with a large integral gain is a manual switch. It is.

(Function) By configuring as described above, the reactive power compensator is normally controlled using an integrating circuit with a large integral gain,
When the grid voltage begins to hunt due to a change in grid capacity, the hunting detection circuit detects the hunting, and the switching circuit switches from an integrating circuit with a large integral gain to an integrating circuit with a small integral gain to control the reactive power compensator. To prevent. When switching from an integrating circuit with a small integral gain to an integrating circuit with a large integral gain after the system voltage has settled into a steady state, the operator must check the system capacity, etc., and then manually switch.

(Example) An embodiment of the present invention will be described using FIG.

Items with the same numbers as those used in the description of the prior art have the same functions. 7-2 is an integrating circuit with a large integral gain, and is expected to provide a high-speed SVC response. 7-3 is an integrating circuit with a small integral gain, and although a high-speed SVC response cannot be expected, it has an integral gain that prevents hunting of the system voltage due to SvC in almost all system conditions. 10 is a hunting detection circuit that detects whether or not the system voltage V is hunting; it outputs "1" when the system voltage is hunting, and outputs "0" when it is not hunting. Reference numeral 11 is a flip-flop. In the initial state, the Q output outputs "0", when "1" is input to the SET input, Q outputs "1", and when "1" is input to the RESET input, Q output is "0". outputs "0". 12-1 is a switch (B contact), 12-2 is a switch (A contact), and when the Q of the flip-flop 11 is outputting "0",
Switch 12-1 is closed and switch 12-2 is open. When the Q of the flip-flop 11 is outputting "1", the switch 12-1 is open, and the switch 12-1 is open.
2 is closed. Reference numeral 13 is a manual reset circuit which outputs "1" when a manual reset is performed, and outputs "0" when a manual reset is not performed. - A portion A surrounded by a dotted chain line corresponds to this embodiment.

The operation of this embodiment will be explained using FIG. First, when the grid operation is normal or no grid fault has occurred, the hunting detection circuit outputs "0" because no hunting occurs in the grid voltage.

Therefore, since the Q output of the flip-flop 11 is rOJ, the switch 12-1 is closed and the switch 12-2 is open. As a result, the output of the integrating circuit 7-2 is input to the phase control circuit 8.

Since this has the same result as the circuit used in the explanation of the prior art, its operation is also the same as that explained in the explanation of the prior art. In other words, the integration circuit 7 with large integral gain
Since -2 is used, a fast SvC response can be expected, and even if the grid voltage differs from the reference voltage, the SvC will immediately maintain it at the reference voltage.

Next, due to system operation circumstances or a system accident, the capacity of the system is reduced to 1/2 or 1/3, for example, and the capacity of the SVC is relatively large compared to the capacity of the system, and the integration circuit 7-2 is A case will be explained in which the integral gain is too large and the system voltage begins to hunt.

When the system voltage V starts hunting, the hunting detection circuit 10 outputs "1". As a result, the Q output of the flip-flop 11 outputs "1". As a result, switch 12-1 opens and switch 12-2 closes. Therefore, the output of the small gain integration circuit 7-3 is input to the phase control circuit 8. Therefore, even if the grid voltage V changes greatly due to hunting, that is, even if the error voltage ΔV changes greatly, the output of the small gain integration circuit 7-3 changes only small, and the output reactive power of the SVC also changes only small. do not. Therefore, SvC does not overcompensate and cause hunting in the grid voltage.

Next, if the operator confirms that the system operation has returned to normal or that the grid fault has been recovered and the system status has returned to normal, and manually sets the output of manual reset 13 to "1", the flip-flop Since the Q output of 11 becomes "0", switch 12-1 is closed and switch 12-2 is opened. As a result, the output of the integrating circuit 7-2 is input to the phase control circuit 8, but since the system state has returned to the normal state, the system voltage does not cause hunting due to SVC.

[Effects of the Invention] As explained above, if the present invention is used, a high-speed response of the reactive power compensator can be expected in normal system conditions, but in system conditions such as a system fault, the reactive power compensator can reduce the system voltage. This has the effect that the problem of hunting can be avoided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional technique. 7-2... Integrating circuit (large gain), 7-3... Integrating circuit (small gain), 10... Hunting detection circuit, 1
1...Flip-flop, 12-1.12-2...
Switch, 13...Manual reset circuit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In a reactive power compensation measure that controls reactive power of the grid according to a deviation between a grid voltage reference and the grid voltage by feeding back the grid voltage in order to stabilize the grid voltage, the feedback a circuit with a large gain, a circuit with a small feedback gain, a circuit that detects hunting in the system voltage, and a switch that responds to the hunting detection circuit to switch from control by the circuit with a large feedback gain to control by a circuit with a small feedback gain. A reactive power compensator comprising a circuit, wherein switching from control by the circuit with a small feedback gain to control by the circuit with a large feedback gain is performed by manual switching.