JPH01129800A - Excitation controller for synchronous machine - Google Patents

Abstract

PURPOSE:To assure optimum dynamic stability at all times by adjusting gain and phase control signals supplied to a power system stabilizer in accordance with the condition of a power supply system. CONSTITUTION:A power system stabilizer 30 receives a signal representing an effective power from a power supply system and adds a power system stabilization signal 105 obtained by controlling the received effective power signal in gain and phase to a voltage deviation signal 104. On the other hand, an output ratio control circuit 32 compares the peak value of absolute value of the stabilization signal 105 with that of a control signal 106 and adjusts the gain of the power system stabilizer based on the result of comparison. In addition, a phase difference control circuit 33 obtained a field voltage simulation value 110 from the output of an AVR model 15 receiving the voltage deviation signal 104, and from a signal obtained by impefectly differentiating the field voltage. Finally, the phase of the power system stabilizer is controlled in accordance with the result of comparison between the simulation value 110 and the imperfectly-differentiated signal of the effective power.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an excitation control device for a synchronous machine, and particularly to a power system stabilizing device suitable for improving the dynamic stability of a power system.

[Conventional technology]

The aim is to improve the dynamic stability of conventional power systems.
As stated on pages 35 to 40 of Hitachi Review Vol.
There is a system 5 tabilizer (hereinafter abbreviated as P'jy).

The principle of operation is as follows.

Fig. 2 is a system model called a one-machine infinite system, which shows one synchronous machine 22 connected to an infinite bus 23 via a beam axle Xe24.
This is explained by the relationship between the operating characteristics of No. 2 and the system impedance. When this operation is linearly approximated for minute power fluctuations, torque ΔT, speed Δω, phase difference angle Δδ, terminal voltage Δ
It can be expressed as Vg as shown in the block diagram shown in FIG. Here, Δ indicates the amount of change, and the same applies hereafter.

In FIG. 3, among the τ gain characteristics given by K s = K 6, only K8 is determined by the impedance of the synchronous machine 22 and the system, but the rest all vary depending on the operating state of the synchronous machine 22 in addition to the impedance. Therefore, the motion of the synchronous machine 22 is treated as a vibration system, and the synchronization torque ΔTs is in phase with the phase difference angle δ, and the braking torque ΔT is in phase with the speed Δω.
If expressed as d, the block diagram shown in FIG. 4 will be obtained, and its vibration characteristic has vibration frequency ω-F=fΣbraking characteristic ρ, and is expressed by the following equation.

Here, S: Differential operator (d/d t) D Two-sided dynamic torque coefficient Kl: Synchronization torque coefficient M: Inertia constant of synchronous machine ω0: Base rotational angular speed Normally, this angular frequency ω is about 5 to 10 rad/s Therefore, even if the system configuration changes significantly, the difference is at most 2~2°rad/
It is about s. In Fig. 4, 1 is the d-axis interlinkage magnetic flux ΔE
(1' is the change coefficient of the electric torque specific to the synchronous machine with respect to the change in the phase difference angle when it is constant, and K11 is the electric torque coefficient generated from the excitation control system.

- The electric torque coefficient fed back as a signal with a phase difference of 90 degrees from the right synchronization torque and the same phase as the rotation speed includes a coefficient specific to the synchronous machine expressed as a control coefficient and a braking torque coefficient D' due to excitation control.

Of these, Kl' is 1 to 10 in the range of normal equipment constants.
~20% or less, and even if it becomes a negative value, it is not much of a problem, but D' can be a negative value of the same magnitude as D, so if D+D'< O, the vibration becomes a divergent system and the dynamic stability is reduced. It is possible that it will be lost. Therefore, in order to ensure dynamic stability, it is necessary to add positive braking torque to compensate for the negative braking torque. To do this, the oscillation signal of the phase difference angle Δδ of the synchronous machine is detected, and the gain It is sufficient to adjust the phase and the phase and provide it to the voltage control system as a correction signal to increase the braking torque of the excitation system, and Pss performs this.

Returning to Figure 4 and organizing the above ideas, in order to improve the dynamic stability, the excitation system torque ΔTex for the phase difference angular fluctuation Δδ must advance approximately 90 degrees in phase with the angular frequency Δω or 90 degrees with respect to -Δδ. Constant voltage control system AVH with delay
It can be seen that it is better to control the Next, from FIG. 3, the relationship between the field voltage ΔVf of the synchronous machine and the excitation system torque ΔTex is determined as follows. Here, the effect due to armature reaction is 4
- Δδ is a small value compared to ΔVf, so it is ignored. In equation (1), 3·Tdo' is usually on the order of several seconds, and the normal power swing angular frequency is 2 to 20red.
Considering that it is within the range of /S, the excitation system torque ΔTe
It can be seen that x lags behind the field voltage ΔVf by approximately 90 degrees.

When the above phase relationship is expressed as a vector together with the phase difference angle Δδ, the relationships shown in FIGS. 5 and 6 are obtained. Excitation system torque ΔTex
is almost in phase with or slightly behind the shaft rotational speed Δω,
In other words, it is sufficient to perform control so that the area falls within the shaded area. In the figure, ΔTax' indicates the maximum allowable phase delay of ΔTex with respect to Δω. Furthermore, from equation (1), ΔVf is Δ
Since it is at a position 90 degrees ahead of Tex, in order to obtain the optimum braking torque, ΔVf must be 180 degrees or Δδ
It can be seen that control should be performed so that Vf and (-Δδ) are approximately in phase.

The above is an explanation of the operating principle of Pss.

[Problem that the invention seeks to solve]

In the above conventional technology, the control constant of the power system stabilizing device is set as a fixed constant according to the predetermined system configuration, and as described in Japanese Patent Application Laid-open No. 15599/1983, the control constant is set according to the system configuration and load condition. Some attempts are made to achieve optimal characteristics by selecting blocks accordingly, but this is not necessarily optimal because the parameters change in a stepwise manner.
In addition, in cases where the system configuration exceeds the theoretical consideration at the time of plant planning, there are problems such as unstable control.

An object of the present invention is to optimally automatically adjust a gain control signal that performs gain control according to the state of the power system, and furthermore, to improve dynamic stability optimally according to the state of the power system. The object of the present invention is to provide an excitation control device for a synchronous machine that automatically adjusts a phase control signal optimally depending on the state of the power system.

Means for Solving Problem C] The above object is a terminal voltage constant control that determines the field amount of the synchronous machine in response to a deviation signal between the terminal voltage of the synchronous machine and the set terminal voltage, and controls the terminal voltage. In the excitation control device for a synchronous machine, the power system stabilization means detects an active power value of the synchronous machine and outputs a power system stabilization signal obtained by subjecting the active power value to predetermined gain control and phase control. and output ratio control means for calculating a gain control signal that sets a ratio of the power system stabilization signal and the deviation signal to a predetermined value and outputting it as a control signal for the gain control. The field voltage of the synchronous machine, the deviation signal, and the valid signal are sent to an excitation control device for a synchronous machine to which a stabilization signal is added, or an excitation control device for the synchronous machine that includes power system stabilization means and output ratio control means. A field voltage component to which the power system stabilization signal contributes is calculated from the field voltage and the deviation signal, and a phase difference between the field voltage component and the active power value is set to a predetermined value. This is achieved by adding a phase difference control means that calculates a phase control signal and outputs it as a control signal for the phase control.

[Effect]

In the above configuration, the power system stabilization means detects the active power value of the synchronous machine, outputs a power system stabilization signal subjected to predetermined gain control and phase control, and compares the terminal voltage of the synchronous machine with the set terminal voltage. In addition to the deviation signal of , the terminal voltage constant control means determines the field amount in response to the corrected deviation signal and controls the terminal voltage. A gain control signal for performing the gain control is calculated and outputted so that the ratio with the deviation signal is a predetermined value, and the phase difference control means calculates and outputs a gain control signal for controlling the gain to a predetermined value. The phase control calculates the field voltage component to which the stabilization signal contributes, and calculates and outputs a phase difference control signal that makes the phase difference between the field voltage component and the active power value a predetermined value.

〔Example〕

An embodiment according to the present invention will be described below with reference to FIG.

FIG. 1 is a diagram showing the configuration of a static excitation device using a thyristor 20.

The terminal voltage v101 of the synchronous machine 22 is transferred to the instrument transformer PT25.
A deviation signal ε1104 between the terminal voltage vg102 stepped down and the voltage setting value V ref (set terminal voltage) 103 of the own 11i11ffi pressure regulator AVR (terminal voltage constant control means) 26 is detected. The deviation signal ε1104 is sent to amplifier A.
Amplify with MPI and further add automatic pulse phaser APPS2
A thyristor gate control pulse is generated, thereby controlling the output voltage of the thyristor 20, that is, the field voltage Vf (field amount) v109 of the synchronous machine 22, and controlling the terminal voltage of the synchronous machine 22 to be constant. In addition, in order to improve the dynamic stability of the power system, the active power Pgll is transferred to the instrument transformer PT.
The Pss output signal V pss (power system stabilization signal) 105 is detected by the power converter 3 through the current transformer CT 25 and the instrument current transformer CT 27, and is subjected to appropriate gain and phase control.
Power system stabilizing device Pss (11 power system stabilizing means) 30 that provides as an auxiliary signal to the signal addition circuit 28 of VR 26
have.

First, gain control will be explained. The deviation signal ε1104 of AVR26 is the output signal Vpss105 of Pss30.
Deviation signal ε2106 and Vpss105 after correction by adding
and an absolute value detection circuit 10a, respectively.

10b and peak value detection circuits 11a and llb, the peak value of the absolute value is detected, and the value obtained by multiplying the peak value by 1 is obtained by the arithmetic unit 12. The deviation between the 1ε2·Kzl peak value and the l Vpss l peak value is calculated by the first-order lag circuit 13.
Pss is removed via the dead band circuit 17a.
30 gain control circuit K pss4 gain control signal'
Give as 107. By performing automatic adjustment to increase the gain of Pss30 when the gain control signal 107 is positive and to decrease the gain of Pss30 when it is negative, the component of Pss30 included in the corrected deviation signal E2106, Vp
ss 105 can always be a constant ratio. In this way, the output ratio control circuit (output ratio control means) 32, which includes the absolute value detection circuits 10a, 10b, the peak value detection circuits 11a, llb, the arithmetic unit 12, the first-order lag circuit 13, and the dead band circuit 17a, determines the system condition. Even if the voltage fluctuation ΔVg becomes large due to a change in the voltage, a change in the power flow condition, etc., the output signal Vpss 105 of the Pss 30 can always be maintained to compensate for the voltage fluctuation ΔVg. Here, Δ indicates the amount of change, and the same applies hereinafter.

Also, Pss30 included in the deviation signal ε2106 after correction
The ratio of the output signal Vpss 105 can be kept constant, and by performing the above control, automatic tuning of the optimal Pss gain for power fluctuations can be performed.

Next, phase control will be explained. Conventional technology Pss3
As explained in the explanation of the operating principle of 0, in order to obtain the optimum braking torque, the field voltage ΔVf108 must be
What is necessary is to perform control such that 180 degrees or ΔVf108 and (−Δδ) are approximately in phase. However, ΔV
As is clear from the block diagram of FIG. 3, f108 also includes the voltage oscillation mode of the voltage control system, so it becomes a composite signal mixed with the power oscillation mode by the Pss output signal V pss105. Therefore, in order to perform the above phase control, it is necessary to control the oscillation component of Vpss105 (power system stabilization signal contribution field) which includes ΔVf108L knee (below the magnetic voltage component ΔV
fpssl 10), that is, the system perturbation signal component ΔV
Detect only fpssl 10, and this ΔVfpssll
It is necessary to control the phase between O and Δδ to be about 180 degrees.

The active power Pgl 11 is detected by the power converter 3, and the change amount ΔPg112 of the active power Pgll is obtained via the incomplete differentiation circuit 14a. Similarly, a field voltage fluctuation ΔVf108 is obtained from the field voltage Vf109 of the synchronous machine 22 via the incomplete differentiation circuit 14b. Input this ΔVf108 and the deviation signal ε1104 of the AVR 26 that controls the terminal voltage of the synchronous machine 22 to a constant value to the AVR model 15, and detect the field voltage simulation value ΔVfε1113 of the synchronous machine 22 that does not match the Pss output signal Vpss105. do.

By taking the deviation between ΔVf108 and ΔVfε1113, the field voltage component Δ of the synchronous machine 22 due to Pss30 is calculated.
Detect Vfpssl 10. Next, phase difference detection circuit 1
6, the phase difference between ΔPgl12 and ΔVfpssl 10, which are one of the power fluctuation signals of the grid, is detected. This phase difference is compared with the phase difference setting value 0refl14, and this phase deviation Δθ115 is sent to the PSD according to the sign of Δθ114 when the absolute value of Δθ115 is a certain value or more.
Phase control signal 1 of phase control circuit θpss 5 of ss30
16 and increase or decrease the phase of Pss30, Δθ1
14 becomes zero. Here, the phase detection circuit 16 has active power ΔPgl12 and ΔVfpssl 10
0FFL when the absolute value of is below a certain level, ON when it is above - room
It has an auxiliary relay to That is, ΔPg112 and Δ
When the absolute value of Vfpss 110 is small, that is, when no power fluctuation occurs, the phase control signal is cut off. In this way, the AVR model 15, the incomplete differentiating circuits 14a and 14b, the phase difference detection circuit 16, and the dead zone circuit 1
7b and a phase difference control circuit (phase difference control means) 33
By.

If the adjustment during the trial run, which sets the gain and phase control constants of the automatic switching device, is to determine the optimal phase control constant for power fluctuations, it is necessary to adjust the step change of the voltage control system or for a two-line power transmission system. By turning the power on and off and generating transient power fluctuations, the optimal Pss constant for the system can be automatically set, making adjustment simpler than in the past. Furthermore, even if external conditions such as system configuration change, automatic tuning can be performed without having to reset constants.

〔Effect of the invention〕

According to the present invention, a power system stabilizing device for improving the dynamic stability of the power system is added to the excitation control device of the synchronous machine,
By providing a means to automatically adjust the gain control and phase control constants of the power system stabilization device, it is possible to always adjust the constants of each control, regardless of the operating status of the synchronous machine, changes in the system configuration, or the type of excitation device. Automatic tuning is possible to automatically adjust the control constants of the power system stabilization device to ensure optimal dynamic stability, which simplifies test adjustments during trial runs and eliminates changes in external conditions such as system configuration and power flow. 0.2 Hz to 2.0
This has an excellent effect of ensuring dynamic stability in a wide frequency band of Hz.

[Brief explanation of the drawing]

FIG. 1 is a construction diagram of an embodiment of the present invention, FIG. 2 is a model diagram of a one-machine infinite system, and FIG. 3 is a block diagram obtained by linearly approximating the model shown in FIG. 2 with regard to power fluctuations. Figure 4 is a diagram in which Figure 3 is replaced with an equivalent two-quasi-oscillation system, Figure 5, ΔP
FIG. 6 is a waveform diagram representing the waveform of FIG. 5. 4... Gain control circuit Kpss, 5... Phase control circuit θpss, 26... Automatic voltage regulator AVR13
0... Power system stabilizer Pss, 32... Output ratio control circuit, 33... Phase difference control circuit, 102...
Terminal voltage Vg, 103... Voltage setting value V ref, 1
04... Deviation signal ε1.105- Pss output signal V
pss, 107--gain control signal, 109...
Field voltage Vf, 110... System oscillation signal component ΔV f
pss, 111...active power Pg, 116...phase control signal.

Claims (1)

[Scope of Claims] 1. A synchronous machine comprising terminal voltage constant control means for determining the field amount of the synchronous machine in response to a deviation signal between the terminal voltage of the synchronous machine and a set terminal voltage and controlling the terminal voltage. In the excitation control device, a power system stabilizing means detects an active power value of the synchronous machine and outputs a power system stabilization signal obtained by subjecting the active power value to predetermined gain control and phase control; output ratio control means for calculating a gain control signal that sets a ratio between the signal and the deviation signal to a predetermined value and outputting it as a control signal for the gain control, the power system stabilization signal being added to the deviation signal. An excitation control device for a synchronous machine characterized by the following. 2. An excitation control device for a synchronous machine comprising a terminal voltage constant control means for determining a field amount of the synchronous machine in response to a deviation signal between a terminal voltage of the synchronous machine and a set terminal voltage and controlling the terminal voltage. a power system stabilizing means for detecting an active power value of the synchronous machine and outputting a power system stabilizing signal obtained by subjecting the active power value to predetermined gain control and phase control; an output ratio control means for calculating a gain control signal that sets a ratio of 1 to a predetermined value and outputting it as a control signal for the gain control; Calculates a field voltage component to which the power system stabilization signal contributes from the field voltage and the deviation signal, and calculates a phase control signal that sets a phase difference between the field voltage component and the active power value to a predetermined value. and a phase difference control means for outputting as a control signal for the phase control, and a power system stabilization signal is added to the deviation signal.