JPH0697880B2 - Excitation control device for synchronous machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation control device for a synchronous machine, and more particularly to a power system stabilizing device suitable for improving dynamic stability of a power system.

[Conventional technology]

For the purpose of improving the dynamic stability of the conventional power system,
Hitachi Review VoL.56, No.12 (1974-12) As described on pages 35 to 40, a power system stabilizer (Power System Stabilizer, abbreviated as Pss) for the purpose of suppressing power fluctuation is is there.

The operating principle is as follows.

Fig. 2 shows one synchronous machine 22 connected to the infinite bus 23 via the reactor Xe24, which is a system model called a one-machine infinity system. It is explained in relation to the impedance. When this operation is linearly approximated to the minute electric power fluctuation, it can be expressed as the torque ΔT and the speed Δω, the phase difference angle Δδ, and the terminal voltage ΔVg as shown in the block diagram of FIG. Here, Δ is the same as the change amount. Of the gain characteristics represented by K _{1 to} K ₆ in FIG. _3, only K ₃ is determined only by the impedance of the synchronous machine 22 and the system, and the rest depends on the operating state of the synchronous machine 22 in addition to the impedance. . Therefore, if the motion of the synchronous machine 22 is treated as an oscillating system, the phase difference angle δ and the in-phase synchronizing torque ΔTs and the speed Δω and the in-phase braking torque ΔTd represent the block diagram shown in FIG. It has a braking characteristic ρ and is expressed by the following equation.

Where S: Differential operator (d / dt) D: Braking torque coefficient K ₁ : Synchronous torque coefficient M: Synchronous machine inertia constant ω ₀ : Base rotational angular velocity Normally, this angular frequency ω _n is about 5 to 10 rad / s Therefore, even if the system configuration changes greatly, it is at most 2 to 20 rad / s.
In FIG. 4, K ₁ is a coefficient of change in electric torque peculiar to the synchronous machine with respect to a change in phase difference angle when d-axis interlinkage magnetic flux ΔEq ′ is constant, and K ₁ ′ is an electric torque coefficient generated from the excitation control system . On the other hand, the electric torque coefficient that is fed back as a signal that is 90 degrees out of phase with the synchronizing torque and in phase with the rotational speed includes a coefficient unique to the synchronous machine represented as a control coefficient D and a braking torque coefficient D'by excitation control.

Of these, K ₁ ′ is 10 to 20% of K ₁ within the range of normal device constants.
It is the following, and it does not matter much if it is a negative value, but D'can be a negative value of the same magnitude as D, so D +
When D '<0, it is considered that the vibration becomes a divergent system and the dynamic stability is lost. Therefore, in order to secure the dynamic stability, it is necessary to apply a positive braking torque so as to compensate for the negative braking torque. For this purpose, the fluctuation signal of the phase difference angle Δδ of the synchronous machine is detected and the gain is increased. And the phase is adjusted and given as a correction signal to the voltage control system so as to increase the braking torque of the excitation system.
It is Pss.

Returning to FIG. 4, summarizing the above idea, in order to improve the dynamic stability, the excitation system torque ΔTex with respect to the phase difference angular fluctuation Δδ leads the angular frequency Δω by approximately 90 degrees in phase or −Δ.
It can be seen that the constant voltage control system AVR, which is delayed by 90 degrees with respect to δ, should be controlled. Next, when the relationship between the field voltage ΔVf of the synchronous machine and the excitation system torque ΔTex is calculated from FIG. Becomes Here, the effect of armature reaction K ₄ · Δδ is ΔVf
Since it is a small value compared to, it is ignored. In the equation (1), K ₃ · Tdo ′ is usually on the order of several seconds, and considering that the normal power fluctuation angle frequency is within the range of 2 to 20 red / S, the excitation system torque ΔTex is relative to the field voltage ΔVf. Almost 9
You can see that it is delayed by 0 degrees.

When the above phase relationship is vector-displayed together with the phase difference angle Δδ, the relationships shown in FIGS. 5 and 6 are obtained. The excitation system torque ΔTex should be controlled so that it is in phase with or lagging behind the shaft rotation speed Δω, that is, in the shaded region. In the figure, ΔTex ′ indicates the maximum allowable phase delay of ΔTex with respect to Δω. Furthermore, from equation (1), ΔVf is 9 from ΔTex.
Since it is at the position advanced by 0 °, it is understood that ΔVf should be controlled so that ΔVf is 180 ° with Δδ or ΔVf and (−Δδ) are almost in phase to obtain the optimum braking torque.

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

[Problems to be solved by the invention]

The above-mentioned prior art is to set the control stability number of the power system stabilizing device as a fixed constant in accordance with a predetermined system configuration, and as described in JP-A-61-15599, the system configuration and load state. There are some that try to realize the optimum characteristics by selecting the block according to the above, but it is not necessarily optimum because the parameters change stepwise, and in the case where the system configuration exceeds the desk study at the time of plant planning. However, there were problems such as unstable control.

An object of the present invention is to automatically and optimally adjust a gain control signal for performing gain control according to the state of the power system in order to always improve the optimal dynamic stability according to the state of the power system. An object of the present invention is to provide an excitation control device for a synchronous machine that automatically and optimally adjusts the phase control signal according to the state of the power system.

[Means for solving problems]

In the excitation control device for a synchronous machine, the object is to provide terminal voltage constant control means for controlling the terminal voltage by 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. , 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, the power system stabilizing signal and the deviation An output ratio control means for calculating a gain control signal having a ratio with a signal as a predetermined value and outputting the gain control signal as a control signal for the gain control, and adding the power system stabilizing signal to the deviation signal to stabilize the power system. An excitation control device for a synchronous machine, characterized in that the gain of a signal to be converted is automatically changed by the output of the output ratio control means, or the synchronization including a power system stabilizing means and an output ratio control means The field voltage of the synchronous machine, the deviation signal, and the active power value are input to the excitation control device, and the field voltage component contributed by the power system stabilization signal is calculated from the field voltage and the deviation signal. A phase difference control means for calculating a phase control signal having a predetermined value as a phase difference between the field voltage component and the active power value and outputting it as a control signal for the phase control is added, and the power system stabilization signal is added. Is automatically changed by the output of the phase difference control means to achieve the excitation control device for the synchronous machine.

[Action]

In the above configuration, the power system stabilizing means detects the active power value of the synchronous machine, outputs a power system stabilizing signal subjected to predetermined gain control and phase control, and outputs the terminal voltage and the set terminal voltage of the synchronous machine. In addition to the deviation signal, the terminal voltage constant control means determines the field amount in response to the corrected deviation signal and controls the terminal voltage, and the output ratio control means controls the power system stabilization signal and the uncorrected signal. A gain control signal for performing the gain control in which the ratio with the deviation signal is set to a predetermined value is arithmetically output, and the phase difference control means further calculates the power system from the field voltage of the synchronous machine and the deviation signal before correction. The field voltage component contributed by the stabilizing signal is calculated, and the phase control calculates and outputs a phase difference control signal that sets the phase difference between the field voltage component and the active power value to 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.

Deviation signal ε ₁ between the terminal voltage Vg102 obtained by stepping down the terminal voltage V101 of the synchronous machine 22 by the voltage transformer PT25 and the voltage set value Vref (set terminal voltage) 103 of the automatic voltage regulator AVR (terminal voltage constant control means) 26. Detect 104. Amplifier the deviation signal ε ₁ 104
It is amplified by AMP1 and the thyristor gated control pulse is generated by the automatic pulse phaser APPS2, which causes the output voltage of the thyristor 20, that is, the field voltage Vf of the synchronous machine 22.
(Field amount) 109 is controlled to control the terminal voltage of the synchronous machine 22 to be constant. Also, in order to improve the dynamic stability of the power system, the active power Pg111 is detected by the power converter 3 via the instrument transformer PT25 and the instrument current transformer CT27, and Pss with appropriate gain and phase control is applied to this. Output signal Vpss (power system stabilization signal) 1
It has a power system stabilizing device Pss (power system stabilizing means) 30 which supplies 05 to the signal adding circuit 28 of the AVR 26 as an auxiliary signal.

First, the gain control will be described. Absolute value detection circuit for the corrected deviation signal ε ₂ 106 and Vpss 105 by adding the output signal Vpss 105 of Pss 30 to the deviation signal ε ₁ 104 of AVR26, respectively.
The peak value of the absolute value is detected via 10a, 10b and the peak value detection circuits 11a, 11b, and the | ε ₂ |
Get the value multiplied by K ₁ . The deviation between the | ε ₂ · K ₁ | peak value and the | Vpss | peak value is removed as ripples by the first-order delay circuit 13 and given as a gain control signal 107 of the gain control circuit Kpss4 of the Pss30 via the dead zone circuit 17a. When the gain control signal 107 is positive, the gain of Pss30 is increased, and when it is negative, the gain of Pss30 is decreased. By performing automatic adjustment, the Pss30 component and Vpss105 included in the corrected deviation signal ε ₂ 106 are always constant. It can be a ratio. Thus the absolute value detection circuit
An output ratio control circuit (output ratio control means) 32 including 10a and 10b, peak value detection circuits 11a and 11b, a calculator 12, a first-order delay circuit 13 and a dead zone circuit 17a, changes in system conditions and power flow conditions. Therefore, even if the voltage variation ΔVg becomes large, the output signal Vpss105 of Pss30 that always exceeds this can be secured. Here, Δ represents a change amount, and the same applies hereinafter. Also, the output signal Vpss of Pss30 included in the corrected deviation signal ε ₂ 106
The ratio of 105 can be made constant, and by performing the above control, automatic tuning of the optimum Pss gain with respect to power fluctuation can be performed.

Next, the phase control will be described. As described in the operating principle of the Pss30 of the prior art, in order to obtain the optimum braking torque, the field voltage ΔVf108 is such that the phase difference angular fluctuation Δδ is 180 degrees or ΔVf108 and (−Δδ) are almost in phase. It suffices to control it. However, since ΔVf108 includes the voltage oscillation mode of the voltage control system as is apparent from the block diagram of FIG. 3, it becomes a composite signal mixed with the power oscillation mode by the Pss output signal Vpss105. Therefore, in order to perform the above phase control, the fluctuation component of Vpss105 included in ΔVf108 (equal to or less than ΔVf
It is necessary to detect only the system fluctuation signal component ΔVfpss110 and control the phase of this ΔVfpss110 and Δδ to be about 180 degrees.

The active power Pg111 is detected by the power converter 3, and this is detected as a change ΔPg112 of the active power Pg111 via the incomplete differentiation circuit 14a.
To get Similarly, the field voltage variation ΔVf108 is obtained from the field voltage Vf109 of the synchronous machine 22 via the incomplete differentiation circuit 14b. AVR26 that constantly controls the terminal voltage of this ΔVf108 and synchronous machine 22
The deviation signal ε ₁ 104 is input to the AVR model 15 to detect the field voltage simulation value ΔVf ε ₁ 113 of the synchronous machine 22 that does not directly include the Pss output signal Vpss 105. This ΔVf 108 and ΔVf
Synchronous machine with Pss30 by taking the deviation from ε ₁ 113
The field voltage component ΔVfpss110 of is detected. Next, the phase difference detection circuit 16 detects the phase difference between ΔPg112 and ΔVfpss110, which is the peak of the power fluctuation signal of the system. This phase difference is compared with the phase difference set value θref114, and when the absolute value of Δθ115 is equal to or larger than a certain value of this phase deviation Δθ115 via the dead band circuit 17b,
According to the sign of Δθ114, it is given as the phase control signal 116 of the phase control circuit θpss5 of Pss30 to increase or decrease the phase of Pss30, and Δ
The control is performed so that θ114 becomes zero. Here, the phase detection circuit 16 has an auxiliary relay that turns off when the absolute values of the active powers ΔPg112 and ΔVfpss110 are below a certain level, and turns on above the certain level. That is, the phase control signal is disconnected when the absolute values of ΔPg112 and ΔVfpss110 are small, that is, when the power fluctuation does not occur. This way AVR model 15
And a phase difference control circuit (phase difference control means) 3 including the incomplete differentiation circuits 14a and 14b, the phase difference detection circuit 16 and the dead zone circuit 17a
By 3, the optimum phase control constant for power fluctuation can be automatically tuned.

As described above, according to the present embodiment, if the adjustment during the trial run for setting the gain and the constant of the phase control of the power system stabilizer is the step change of the voltage control system or the two-line transmission system, these adjustments are performed. Since the optimum Pss constant in the system can be automatically set by turning on / off one line and generating a transient power fluctuation, adjustment can be simplified compared to the conventional method. Moreover, even if external conditions such as the system configuration change, automatic tuning without resetting the constant is effective.

〔The invention's effect〕

According to the present invention, in the excitation control device of the synchronous machine, a power system stabilizing device for improving dynamic stability of the power system is added,
By providing means for automatically adjusting the constants of the respective controls for the gain control and phase control of the power system stabilizing device, regardless of the operating state of the synchronous machine, changes in the system configuration, and the type of exciter, Since automatic tuning that automatically adjusts the control constants of the power system stabilizer to ensure optimum dynamic stability can be performed, test adjustment during test run can be simplified and external conditions such as the system configuration and power flow can be changed. However, the constant resetting can be omitted, and because it is automatically adjusted to the optimum control constant according to the vibration cycle of the power system, dynamic stability in a wide frequency band of 0.2 Hz to 2 Hz can be secured, which is excellent. effective.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment according to the present invention, FIG. 2 is a model diagram of a one-machine infinity system, and FIG. 3 is a block diagram in which the model shown in FIG. FIG. 4 is a diagram in which FIG. 3 is replaced by an equivalent two-like vibration system, FIG. 5, and ΔP
And a vector diagram showing an ideal vector relationship between Δω and ΔVf, and FIG. 6 is a waveform diagram representing the waveform of FIG. 4 ... Gain control circuit Kpss, 5 ... Phase control circuit θps
s, 26 …… Automatic voltage regulator AVR, 30 …… Power system stabilizer Pss, 32 …… Output ratio control circuit, 33 …… Phase difference control circuit, 102 …… Terminal voltage Vg, 103 …… Voltage setting value Vref, 10
4 …… Deviation signal ε ₁ , 105 …… Pss output signal Vpss, 107 ……
Gain control signal, 109 ... field voltage Vf, 110 ... system fluctuation signal component ΔVfpss, 111 ... active power Pg, 116 ... phase control signal.

Claims (2)

[Claims] 1. An excitation control device for a synchronous machine, comprising terminal voltage constant control means for determining a field amount of the synchronous machine according to a deviation signal between a terminal voltage of the synchronous machine and a set terminal voltage and controlling the terminal voltage. In, a power system stabilizing means for detecting an active power value of the synchronous machine and outputting a power system stabilizing signal subjected to predetermined gain control and phase control to the active power value, the power system stabilizing signal and the An output ratio control means for calculating a gain control signal having a ratio with a control signal as a predetermined value and outputting the gain control signal as a control signal for the gain control, wherein the gain of the power system stabilizing signal is output by the output ratio control means. An excitation control device for a synchronous machine, characterized in that it is automatically changed according to. 2. An excitation control device for a synchronous machine, comprising terminal voltage constant control means for determining a field amount of the synchronous machine according to a deviation signal between a terminal voltage of the synchronous machine and a set terminal voltage and controlling the terminal voltage. In, a power system stabilizing means for detecting an active power value of the synchronous machine and outputting a power system stabilizing signal obtained by performing predetermined gain control and phase control on the active power value, the power system stabilizing signal and the An output ratio control means for calculating a gain control signal having a ratio with a deviation signal as a predetermined value and outputting the gain control signal as a control signal for the gain control, a field voltage of the synchronous machine, the deviation signal, and the active power value. Phase control in which a field voltage component contributed by the power system stabilization signal is calculated from the input field voltage and the deviation signal and the phase difference between the field voltage component and the active power value is set to a predetermined value. Of the phase control And a phase difference control means for outputting a control signal, excitation control apparatus of the synchronous machine, characterized by automatically changing the phase of said power system stabilizing signal by the output of the phase difference control means.