JPH0246136A - Reactive power regulator - Google Patents

Abstract

PURPOSE:To improve the stability and quick response by calculating a variable gain based on the voltage, reactance, transformation rate and the like at each point in a power system then regulating the voltage at a specific point based on the calculated variable gain. CONSTITUTION:A reactive power regulator 13 receives generator voltage and generator current from a potential transformer 7 and a current transformer 8 and calculates a reactive power, which is then compared with an output from a reactive power setter 9. Then the difference is multiplied by a variable gain 14 and fed to a regulator 15 for regulating the field ot a generator 2. The variable gain is calculated through a formula (2V-nVB)/nx, where n is the turn ratio of transformer, x is the reactance of the transformer, V is the generator voltage and VB is the bus voltage. These parameters are inputted from the outside or stored previously.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention provides reactive power of power equipment,! &Int device.

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(Prior Art) FIG. 2 shows an example of a system configuration of a conventional reactive power adjustment device Fa1. In the figure, a generator 2 is connected to a bus bar 4 via a transformer 3, and supplies active power and reactive power.

The voltage of the generator 2 is controlled by an automatic voltage regulator 5 (hereinafter referred to as AVR) by manipulating the current flowing through the field winding 6. The generator voltage and generator current are input to the reactive power adjustment device 1 using an instrument transformer 7 and a current transformer 8, respectively, and the reactive power adjustment device 1 calculates reactive power from these inputs and adjusts the reactive power. Match it with the output of the power setting device 9. The control deviation obtained by matching is amplified by a proportional amplifier 10, further subjected to pulse width modulation by an interrupter 11, and outputted from the reactive power adjustment device 1 to operate the voltage setting device 12 of the AVR 5.

In this way, the reactive power adjustment device 1 controls the reactive power by changing the voltage of the generator 2 with respect to the voltage of the bus 4 by operating the voltage setting of the AVR 5.

That is, in the PU method, when the generator voltage is higher than the bus voltage, a reactive current flows from the generator 2 toward the bus 4 depending on the difference and the reactance of the transformer 3, and from the generator 2 (
When the voltage of the bus 4 is high, the (lagging phase) reactive power is supplied from the bus 4 to the generator 2. In the former case.

In the latter case, generator 2 is in a state of lagging power factor.

It is in a state of leading power factor. In the latter case, it can also be said that phase-advanced reactive power is being supplied.

In such a reactive power control system, generator voltage and reactive power have a nonlinear relationship, and the amount of change in reactive power with respect to the amount of change in generator voltage is not constant, and the values of generator voltage and bus voltage at that time are not constant. Depends on. The bus voltage is also generally influenced by the generator voltage. Therefore, when the voltage setting device 12 is operated from the reactive power adjustment device 1, a control amount change, that is, a reactive power change that is proportional to the change in operation cannot be expected. However, the conventional reactive power W14 adjustment device 1 performs feedback control, and stable control can be achieved by sacrificing fast dissolution to some extent.

(Problems to be Solved by the Invention) Therefore, the conventional reactive power adjustment device 1 ignores quick solubility for the sake of control stability, and also from the viewpoint that frequent voltage fluctuations are undesirable, quick solubility is not always necessary. It wasn't necessary.

However, recently there has been a demand for countermeasures against voltage fluctuations in power systems, and rapid dissolution control of reactive power has also become necessary. In addition, in terms of power generation equipment itself, not only conventional generators but also equipment with easy output adjustment such as batteries are being developed, and combined with advances in digital technology, there is a need for free control of reactive power.

An object of the present invention is to provide a reactive power adjusting device with improved stability and quick solubility.

[Structure of the invention]

(Means for Solving the Problems) The present invention controls a nonlinear system as if it were a linear system by incorporating into an adjustment device a variable gain that compensates for nonlinear characteristics ranging from generator voltage fluctuations to reactive power fluctuations. In compensating for nonlinear characteristics, the variable gain is determined by approximating the nonlinear characteristics as depending on the system voltage actance and transformation ratio.

(Function) Input the required grid voltage and use this, grid actance, and transformation ratio as parameters to determine the variable gain.
Even if the response characteristics of reactive power change due to fluctuations in system voltage, stable control can always be performed, and rapid solubility can be improved based on this stability.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the system configuration of an embodiment of the present invention.

The same parts as in the prior art are given the same reference numerals and their explanation will be omitted.

In the figure, reactive power 11a1! The device 13 inputs the generator voltage and the generator current from the current transformer 8 of the seven instrument transformers, calculates the reactive power, and compares it with the output of the reactive power setting device 9. Control deviation dQ obtained by matching
is input to the regulator 15 after being multiplied by the variable gain 14, and the output of the regulator 15 is the variation dV of the manipulated variable. The variation dV of the manipulated variable is pulse width modulated by the interrupter 11 and output from the reactive power adjustment device 13, and the AVR 5
The variable gain 14 is integrated by the heavy pressure setting device 12 and becomes the voltage set value. It is calculated from the ratio n.

The basis for calculating the variable gain 14 is as follows.

We ignore the system resistance and assume that the reactive power depends only on the voltage magnitude. This assumption fits well with reality.

Then, P: active power V; generator voltage Q; reactive power vB; bus voltage n: transformer transformation ratio; In this case, a steady voltage increment dV corresponding to the reactive power deviation dQ can be obtained. In this embodiment, a PID controller 15 is further added as a dynamic adjustment element.

Therefore, changes in response characteristics due to voltage fluctuations are caused by variable gain 14.
The PID regulator I5 can always maintain optimal adjustment.

〔Effect of the invention〕

According to the present invention, it is possible to perform reactive power control that compensates for changes in reactive power response characteristics due to system voltage changes and always maintains an optimal adjustment state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional reactive power adjustment device. 13... Reactive power adjustment device 14... Variable gain

Claims (1)

[Claims] A device that controls reactive power or power factor by manipulating the voltage at a predetermined point in power equipment, and inputs or stores the required voltage, reactance, transformation ratio, etc. of each part of the power system related to the point, and inputs or stores the various values thereof. A reactive power adjustment device that controls reactive power by calculating a variable gain from and using this variable gain to manipulate the voltage at the point.