JP2000259268A - Device for compensating static reactive power - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the total control gain of a static reactive power compensating device by providing a reactive power controlling means with a gain controlling part which calculates a control gain in accordance with voltage of a power system. SOLUTION: A controller 1 being a reactive power controlling means is connected to a power system 3, and a reactive power generation circuit 2 generating a reactive power is connected to the system 3 through a step-down transformer 21. An output form a voltage detecting part 11 detecting the voltage of the system 3 is connected to a gain controlling part 16 adjusting a control gain K, and the gain K is outputted to a ΔQ operating part 13. Also, a set voltage stored in a set voltage storing part 12 and a deviation voltage ΔV due to voltage outputted by the part 11 are outputted to the part 13. Due to such a configuration, the total control gain of a static reactive power compensating device is made uniform even in both voltage step-up and step-down control modes without being affected by the voltage fluctuation at a set point, and a fast and stable response characteristics can be obtained all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static var compensator connected to a power system to maintain a system voltage.

[0002]

2. Description of the Related Art In a power system to which a large-capacity motor or the like is connected, a large voltage fluctuation occurs when the large-capacity motor is started. One of the effective devices for suppressing voltage fluctuation due to such large capacity and sudden load fluctuation is a static var compensator, which operates as a leading var load when the system voltage is low. In addition, when the system voltage is rising, it operates as a delayed reactive power load to compensate for system voltage fluctuations.

[0003] A conventional static var compensator will be described below. FIG. 3 shows an explanatory diagram of a conventional static var compensator. 30 is a control device, 40 is a reactive power generation circuit, 50 is a power system, 41 is a step-down transformer, and 42 is the first
, 43 is a second reactor, 44 is a phase control switch means, 45 is a capacitor, 31 is a voltage detection circuit, 32 is a set voltage storage unit, 33 is a ΔQ ₁ calculation unit, 34
Denotes an integration processing unit, and 35 denotes a phase control switch control unit.

The operation of the conventional static var compensator configured as described above will be described below.

First, a reactive power generation circuit 40 operating as a reactive power load is connected to the low voltage side via a power system 50 and a step-down transformer 41. When the voltage V _T of the power system 50 measured by the voltage detection circuit 31 decreases, the control device 30 controls the reactive power generation circuit 40 to control the phase control switch means 44 to operate as a leading reactive power load, and the voltage V _T if rises, the voltage is constant controlled to maintain a set voltage set voltage storage unit 32 which the system voltage is provided to the control device 30 operates as a lagging reactive power load.

Specifically, the voltage V of the power system 50 measured by the voltage detection circuit 31 provided in the control device 30
It is compared with the voltage set value of _T setting voltage storage unit 32 that deviations are output to Delta] Q ₁ arithmetic unit 33. The ΔQ ₁ calculator 33 multiplies the input deviation by the control gain K ₀ to calculate the reactive power ΔQ ₁ , which is the output change of the reactive power generation circuit 40. In order to eliminate the steady-state deviation of the control system, the integration processing section 34 integrates the input reactive power ΔQ ₁ and performs a reactive power generation circuit 40.
_Is calculated and output to the phase control switch control unit 35.

[0007] The phase control switch control section 35 to which the reactive power Q ₀₁ has been input outputs the control firing angle α ₁ of the phase control switch means 44 for the reactive power generation circuit 40 to output the reactive power of Q ₀₁ . However, the output control firing angle α ₁ is a value assuming that the rated voltage V ₀ is applied to the reactive power generation circuit 40.

The reactive power generation circuit 40 operates the phase control switch means 44 at the timing of the input control firing angle α ₁ to supply the reactive power Q ₀₁ to the power system 50, thereby obtaining the voltage V _T of the power system 50. Of the voltage V _T
Can be set to the voltage set in the set voltage storage unit 32.

[0009]

As described in the prior art, the static type reactive power compensator uses the power system 50.
In the process of the voltage V _T constant, control ignition angle phase control switch controller 35 inputs the reactive power Q ₀₁ alpha ₁
Is output to the reactive power generation circuit 40 by the rated voltage V.
_O is applied, and when the voltage V _T of the power system 50 is the rated voltage V _O , the reactive power generation circuit 4
0, an accurate reactive power Q ₀₁ is output.
0 reactive power Q outputted from the reactive power generation circuit 40 when the deviation from the rated voltage V _O is the voltage V _T by the voltage variation of
₁ is considered to be the following equation, and the reactive power _Q01 is not accurately output.

[0010]

(Equation 1)

For this reason, when a deviation voltage ΔV occurs between the voltage V _T of the power system 50 and the voltage of the set voltage storage unit 32, the reactive power input to the phase control switch control unit 35 changes from Q ₀₁ to Q ₀₂ . If it changes, the reactive power generation circuit 40
The reactive power change Δq ₁ output from

[0012]

(Equation 2)

And the total control gain of the reactive power compensator represented by the ratio of the reactive power change Δq _{1 to} the deviation voltage ΔV is

[0014]

(Equation 3)

And depends on the voltage V _T of the power system 3.

Therefore, the total control gain differs between the case where the voltage rise and the case where the voltage drop occur in the power system 50. If the control gain K _O is a fixed value, the boost control is performed. The response characteristic changes between the time and the step-down control. In this case, an overshoot occurs in the step-down control when the increase uniformly the control gain K _O in order to increase the response speed during the boost control, V _T of the power system 3 is changed to the voltage value of the target voltage range and out While converging within the target voltage range, the voltage V
There has been a problem that the response time until _T falls within the target range becomes longer and the response speed also decreases.

The present invention solves the above-mentioned conventional problems. In both the step-up control and the step-down control, the total control of the static var compensator is not affected by the voltage fluctuation at the installation point. It is an object of the present invention to provide a static var compensator capable of uniform gain and easily obtaining a high-speed and stable response characteristic.

[0018]

In order to achieve the above object, a first means of a static var compensator according to the present invention comprises: a reactive power generating circuit connected to a power system for generating reactive power; Reactive power control means for controlling the reactive power, wherein the reactive power control means has a gain adjustment unit for calculating a control gain according to the voltage of the power system.

The second means is connected to a power system and generates a reactive power, a reactive power generation circuit, a voltage detector for detecting a voltage of the power system, and stores a set voltage to change the set voltage. A settable voltage storage unit, a constant voltage control unit that receives an output of the voltage detection unit and controls the reactive power generation circuit so that the voltage of the power system becomes the set voltage, and an output of the voltage detection unit. A gain adjustment unit that calculates a control gain according to the voltage constant control unit,
The reactive power generation circuit is controlled by a control gain output from the gain adjustment unit.

Further, the third means is the first means or the second means, wherein the control gain is minus 2 of the voltage of the power system.
It is proportional to the power.

[0021]

In order to achieve the above object, a first means of a static var compensator according to the present invention comprises: a reactive power generation circuit connected to a power system for generating reactive power; And reactive voltage control means for controlling the reactive power control means, the reactive power control means having a gain adjustment unit that calculates a control gain according to the voltage of the power system,
A high-speed and stable response characteristic can be obtained in both the step-up control and the step-down control of the voltage of the power system and without being influenced by the fluctuation of the voltage applied to the reactive power generation circuit.

The second means is connected to a power system and generates a reactive power, a reactive power generation circuit, a voltage detector for detecting a voltage of the power system, and stores a set voltage and stores the set voltage. A set voltage storage unit capable of changing the set voltage, a voltage constant control unit that receives an output of the voltage detection unit and controls the reactive power generation circuit so that the voltage of the power system becomes the set voltage; A gain adjustment unit that calculates a control gain according to the output of the voltage detection unit, wherein the constant voltage control unit controls the reactive power generation circuit with a control gain output from the gain adjustment unit. Therefore, the voltage of the power system can be accurately and quickly adjusted to the set voltage regardless of the fluctuation of the voltage applied to the reactive power generation circuit in both the step-up control and the step-down control. I was able to respond.

Further, the third means is the first means or the second means, wherein the control gain is minus 2 of the voltage of the power system.
Since it is proportional to the power, the voltage of the power system can be accurately adjusted to the set voltage regardless of fluctuations in the voltage applied to the reactive power generation circuit during both boost control and step-down control. Fast and stable response is possible.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
It will be described based on.

(Embodiment) FIG. 1 is an explanatory diagram of a static var compensator showing an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a control device which is a reactive power control means connected to a power system 3, and 2 denotes a reactive power generating circuit which generates reactive power, which is connected to the power system 3 via a step-down transformer 21. I have.

Reference numeral 11 denotes a voltage detection unit for detecting the voltage of the power system 3, and its output is connected to a gain adjustment unit 16 for adjusting a control gain K.
Is output to

Reference numeral 12 denotes a set voltage storage unit for storing a set voltage, which can be changed. The deviation voltage ΔV between the set voltage and the voltage output from the voltage detector 11 is sent to the ΔQ calculator 13. Has been output.

The .DELTA.Q calculating section 13 calculates a reactive power .DELTA.Q proportionally calculated based on the inputted deviation voltage .DELTA.V and the control gain K.
Is output to the integration processing unit 14.

The integration processing unit 14 integrates the reactive power ΔQ to calculate a reactive power Q _O , and the phase control switch control unit 1
5 is output. The control firing angle α calculated by the phase control switch control unit 15 is output to the reactive power generation circuit 2.

The above-described ΔQ calculation unit 13, integration processing unit 14, and phase control switch control unit 15 correspond to a constant voltage control unit, but are not limited to this.

The reactive power generation circuit 2 includes a phase control switch 24 controlled by the control firing angle α, and a first reactor 22 connected in series with the phase control switch 24.
And a series circuit of a second reactor 23 and a capacitor 25 connected in parallel with the first reactor 22. The step-down transformer 21 is connected.

[0033] In operation the above construction, the gain adjustment unit 16 inputs the voltage V _T of the power system 3 measured by the voltage detection unit 11 sequentially, the voltage V _T of the power system 3 as a variable parameter Determine the control gain K.

In FIG. 1, a phase control switch control unit 1
5, the operation of inputting the reactive power Q _O and outputting the control firing angle α is performed when the applied voltage of the reactive power generation circuit 2 is the rated voltage V _O.

[0035]

(Equation 4)

[0036] As in the thought that the reactive power Q outputted from the reactive power generator 2 is changed to ^twice (V _T / V _O) against the reactive power Q _O which is a command value, correcting the variation The control gain K _O which has been conventionally used is changed to (V _O / V
_T) are determined ^twice the like of the control gain K and the following equation.

[0037]

(Equation 5)

Therefore, when the deviation voltage ΔV is generated,
The reactive power input to the phase control switch control unit 15 is Q
_The reactive power change Δq output from the reactive power generation circuit 2 when the value changes from ₁ to Q ₂ is:

[0039]

(Equation 6)

The total control gain of the reactive power compensator represented by the ratio of the reactive power change Δq to the deviation voltage ΔV is

[0041]

(Equation 7)

This is independent of the voltage V _T of the power system 3.

Thus, in both the step-up control and the step-down control, the control gain of the static var compensator as a whole is made uniform without being influenced by the voltage fluctuation at the installation point. Response characteristics can be obtained.

FIG. 2 shows a response characteristic diagram of the output reactive power and the installation point voltage of the static var compensator. A voltage response in a case where the time when a voltage change occurs is set as a starting point of time, and a time required to reach a target range 31 in which the voltage is to be controlled is considered as a response time with respect to a control target voltage 30 at a static reactive power compensator installation point The characteristics and the output reactive power response characteristics are shown on the same graph for both the step-up control and the step-down control.

As shown in FIG. 2, in the conventional control, the boosting control is applied to the response time T _L 52 when the control gain K ₀ is set so that the voltage response characteristic 36 during the step-down control falls within the target range 31. Time T _U 53 of the voltage response characteristic 34 at the time
Becomes quite long.

If the control gain K ₀ is increased to shorten the response time T _U 53 of the voltage response characteristic 34 during the boost control, the voltage response characteristic 36 during the step-down control overshoots. the voltage V _T time response to change the target range inside and outside becomes rather long to fit.

[0047] This is because, as described above, the control gain of the reactive power compensator total represented by the ratio of the reactive power variation [Delta] q ₁ for deviation voltage ΔV is (1) the voltage V _T of the power system 3 as This is because they are affected by fluctuations.

On the other hand, in the present embodiment, the response time of the voltage response characteristic 33 during the boost control with the control gain K based on the equation (2) and the response time of the voltage response characteristic 35 during the step-down control are both T ₀ 51 And the response characteristics become uniform.

[0049] Then, as described above, the control gain of the reactive power compensator total represented by the ratio of the reactive power variation Δq for the deviation voltage ΔV is (3) of the voltage V _T of the power system 3 as represented by the formula Since the control gain K is not affected by the fluctuation, the control gain K can be easily set to the optimum value.

[0050] Further, although shorter than the response time T _L 52 is the response time in this embodiment T ₀ 51 in FIG. 2, the response time is the step-down control voltage V _T in the power system 3 falls within the target range In the present embodiment, the response time in the conventional control is T ₀ 51 in comparison with T _U 53 because the response time in the conventional control is longer than the response time in the time or step-up control. Therefore, the response time that converges on the target range 31 is shorter than in the conventional control.

The conventional output reactive power response characteristic 38 at the time of boost control and the output reactive power response characteristic 40 at the time of step-down control corresponding to the above, the output reactive power response characteristic 37 at the time of step-up control and the step-down control of the present embodiment. FIG. 2 also shows the output reactive power response characteristic 39 at the time.

That is, by appropriately increasing the control gain K ₀ , it is possible to obtain a high-speed and stable response characteristic up to the limit of overshoot in both the step-up and step-down control.

When the set voltage V ₁ held in the set voltage storage unit 12 is different from the rated voltage V ₀ ,
_The response characteristics can be made uniform over the entire voltage range without depending on ₁ .

[0054] That is, does not depend on the voltage of the electric power system, be modified set voltage V _1, always control gain of the static var compensator total is kept constant, to obtain stable uniform response characteristics Can be.

Incidentally, the control gain determining means in the gain adjusting section can be changed according to the calculation contents and the holding contents of the phase control switch control section 15 and the intended response characteristics.

Although the control device 1 and the voltage detection circuit 11 of the above embodiment are shown in a block diagram, they may be entirely or partially processed by hardware or a microcomputer.

[0057]

As described above, according to the present invention, in both the step-up control and the step-down control, the total control gain of the static var compensator is independent of the voltage fluctuation at the installation point. And a static reactive power compensator always having a high-speed and stable response characteristic can be provided.

Further, the response characteristics can be made uniform over the entire voltage range without depending on the set voltage of the power system.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a static var compensator according to an embodiment of the present invention;

FIG. 2 is a response characteristic diagram of the static var compensator according to the embodiment;

FIG. 3 is an explanatory diagram of a conventional static var compensator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control device 2 reactive power generation circuit 3 power system 11 voltage detection unit 12 set voltage storage unit 13 ΔQ calculation unit 14 integration processing unit 15 phase control switch control unit 16 gain adjustment unit 21 step-down transformer 22 first reactor 23 second Reactor 24 Phase control switch 25 Capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Yoshitake 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 5G066 DA04 FA01 FB08 FC13 FC14 5H420 BB02 BB16 CC04 DD03 DD06 EA03 EA27 EA44 EB05 EB26 EB38 FF03 FF22 GG01 HJ07

Claims (3)

[Claims] A reactive power generation circuit connected to a power system for generating reactive power; and a reactive power control means for controlling the reactive power, wherein the reactive power control means responds to a voltage of the power system. A static var compensator having a gain adjuster for calculating a control gain. 2. A reactive power generation circuit connected to a power system for generating reactive power, a voltage detection unit for detecting a voltage of the power system, a set voltage storage unit for storing and changing a set voltage, A constant voltage control unit that inputs the output of the voltage detection unit and controls the reactive power generation circuit so that the voltage of the power system becomes the set voltage, and calculates a control gain according to the output of the voltage detection unit A static var compensator comprising a gain adjuster, wherein the constant voltage controller controls the var generator by a control gain output from the gain adjuster. 3. The static var compensator according to claim 1, wherein the control gain is proportional to a minus square of the voltage of the power system.