JP3234729B2 - Power system stabilizer and control method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power system stabilizing device (PSS) for controlling an exciting device of a synchronous generator, and more particularly to a power system stabilizing control method for optimizing a dynamic steady state stability.

[0002]

2. Description of the Related Art As shown in FIG. 2, many conventional power system stabilizing devices aim to improve the average stability against changes in the operating state of a synchronous machine. P surrounded by a dashed line in FIG.
SS is an instrument transformer (P
T) 3 and the active current (P) from the current transformer (CT) 4 are detected by the active power detection device 6, the change (ΔP) is extracted from the signal P via the DC component removing circuit 12, and the ΔP signal is increased. The gain adjustment circuit 10 adjusts the signal gain and the phase adjustment circuit 19 adjusts the signal phase so that the terminal voltage (VG) sometimes increases and VG decreases when the ΔP signal decreases.

The PSS output Vpss adjusted in this way
Is input to an automatic voltage regulator (AVR) surrounded by a two-dot chain line. The AVR signal adding circuit 18 applies Vpss, the reference voltage Vref, and the terminal voltage VG (negative), increases or decreases the output, and supplies the output to the exciter 2 to dynamically generate a Gen-AVR system (excitation system). Improves stability.

[0004] In the above example, the set values of the gain adjustment circuit and the phase adjustment circuit are fixed, but a PSS has been proposed in which these values are changed in accordance with the operation state to further improve the dynamic stability. The method described in Japanese Patent Application Laid-Open No. 61-280714 has two PSSs for detecting a generator output and a generator rotation speed or a system frequency, and sets a time constant of a phase correction element according to a fluctuation amount of the generator. Change. JP-A-1-10
The method described in Japanese Patent No. 3199 detects a period of power fluctuation, and corrects a phase advance / delay circuit by fuzzy inference based on the change.

[0005]

In a conventional PSS in which a set value is changed in accordance with an operation state, the structure is complicated to correct the time constants of a plurality of circuits, or the correction is made by inference from one input. Therefore, there is a problem that the accuracy of correction is low.

SUMMARY OF THE INVENTION It is an object of the present invention to estimate an operating state from a plurality of input signals and to easily and accurately correct a gain.
An object of the present invention is to provide a power system stabilizing device capable of improving the dynamic steady state stability and a control method using the same.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power system stabilizing device for preventing the output of a synchronous machine from becoming unstable and maintaining stable control when an input signal is abnormal or a system fault, and a control method using the same. Is to do.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power system stabilizing device for stabilizing a power system, wherein a power fluctuation decay rate is obtained from a change in active power, and an active power gain is determined in accordance with the decay rate. Is updated and A is calculated from the change in the system frequency.
Calculating a phase difference due to a delay of VR, updating a phase correction gain according to the phase difference, multiplying the active power or a change thereof by the active power gain, the frequency or a change thereof and the phase correction gain; This is achieved by inputting the AVR as a vector sum with the multiplied value of.

The correction of the active power gain is characterized in that when the attenuation rate is equal to or less than a reference attenuation rate, the gain before updating is multiplied or added by a predetermined value.

When the attenuation rate is equal to or less than a reference attenuation rate, the phase correction gain multiplies or adds a gain before updating by a predetermined value, and the phase difference due to the delay of the AVR includes 0 in its range. When the value exceeds the range, a value that increases positively or negatively according to the phase difference is added.

[0011] The phase difference due to the delay of the AVR is a difference between the phase of the system frequency or the rotation speed of the generator and the phase of the internal induced voltage of the excitation device.

Another object of the present invention is to provide a power system stabilizing device for stabilizing a power system, the power fluctuation damping rate and the frequency estimated from the active power and frequency of the system and the internal induced voltage of the exciter. Based on the fluctuation, the ratio of the active power gain and the phase correction gain multiplied by the active power (or the change) and the frequency (or the change) having a phase difference of 90 ° is dynamically changed, so that the frequency and the internal induced voltage are changed. Is determined by determining the PSS output such that the phases of the PSS and PSS are equal.

Further, the object of the present invention is achieved by updating the active power gain and the phase correction gain through predetermined restrictions.

[0014]

According to the present invention, the operating state of the synchronous machine, that is, the power fluctuation decay rate and the frequency / phase difference due to the AVR system delay are estimated based on the input signal from the system and the like. Since the active power gain and the phase correction gain can be dynamically changed, it is possible to improve the stability adapted to the operation state.

Further, a weight addition coefficient limiter, a weight addition coefficient rate-of-change limiter, and a system fault detection device limit the updating of the active power gain and the phase correction gain. Stable operation can be secured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a power system stabilizing device (P) according to the present invention.
FIG. 2 is a configuration diagram of an excitation system (AVR-Gen system) to which SS) is applied. In the same figure, the dashed-dotted line surrounds the PS according to one embodiment.
The configuration of S is shown.

The PSS of this embodiment uses an active power P and an internal frequency f as input signals as power system fluctuation information. The active power P is detected from PT3 and CT4 by the active power detection device 5, and the frequency f is detected from PT3 by the frequency detection device 6.

The active power P is multiplied by a weight addition coefficient −Kp in a P gain adjustment circuit 10, and the frequency f is multiplied by a weight addition coefficient Kf in an f gain adjustment circuit 11. Take as input. As described above, the gain adjustment and the phase adjustment are realized by adjusting the weighted addition coefficients −Kp and Kf of the P gain adjustment circuit 10 and the f gain adjustment circuit 11 and adding two signals.

The DC component removing circuit 12 is constituted by an incomplete differentiating circuit, and removes a DC component from an added signal of the active power and the frequency so as to leave only an AC component as system fluctuation information.
The output of the DC component removing circuit 12 is set to the PSS output signal Vpss via the output limiter 17 so that an excessive output signal is not supplied to the AVR signal adding circuit 18.

The PSS output signal Vpss is supplied to the signal adding circuit 18 as an auxiliary signal to the automatic voltage regulator AVR. The AVR amplifies the output signal of the signal addition circuit 18 by the amplifier circuit 14 and controls the exciter 2 to change the field current of the synchronous machine 1 and optimize the dynamic steady state stability. It is configured.

By the way, the internal induced voltage Eq ′ obtained by the induced voltage detecting circuit 7 from the active power P and the frequency f, the field voltage Vf of the exciter 2 and the field current If is used as a state estimator 8.
To enter. The state estimator 8 determines the attenuation rate σ and the oscillation frequency (△ θ) from these input signals, and inputs them to the weight addition coefficient calculation circuit 9 to calculate the weight addition coefficients of the active power P and the frequency f. Then, the values of the weight addition coefficients -Kp and Kf of the P gain adjustment circuit 10 and the f gain adjustment circuit 11 are dynamically changed.

FIG. 3 shows the configuration of the state estimator 8 and the weight addition coefficient calculation circuit 9. The state estimator 8 calculates the change amount {P,} of each of the active power P, the frequency f, and the internal induced voltage Eq ′.
f, change detection circuits 20, 21, 22 for detecting △ Eq '
have. The change detecting circuits 20, 21, 22
Has the same configuration as the DC component removing circuit 12.

The amplitude value detection circuit 23 detects the amplitude value A of ΔP, compares it with the amplitude reference value Aref by the amplitude value comparator 24, and inputs ΔP to the attenuation rate detection circuit 25 when A ≧ Aref. To detect the attenuation rate σ. As shown in FIG. 4, since the amplitude curve of ΔP is A = Bε (−σt), the current attenuation rate σ of the power fluctuation can be obtained from this.

The attenuation rate comparator 26 compares the attenuation rate σ with an attenuation rate reference value σref1, and when σ ≦ σref1, sets a positive number (weight?) Α to 1 or more (α ≧ 1). The weight addition coefficient adder / subtractor 27 calculates the weight addition coefficients Kp and Kf ′ by (Equation 1), and increases the weight addition coefficient (Kold) every cycle to increase the power fluctuation attenuation rate. When the current attenuation rate σ exceeds the reference value σref1, the weight addition coefficient K
p and Kf 'are not changed.

[0026]

Kp = αKpold Kf ′ = αKfold The positive number α may be added instead of multiplying (Equation 1). As a result, the power fluctuation attenuation rate σ
Is determined, the weight addition coefficient Kp of the P gain adjustment circuit 10 corresponding to.

On the other hand, the weighting addition coefficient Kf of the f gain adjustment circuit 11 needs to be determined by further correcting Kf ′ obtained by (Equation 1) so that the phase of the variation statement of the frequency matches the internal induced voltage. There is.

By the way, there is a strong correlation between the power fluctuation and the frequency fluctuation of the system. FIG. 5 is a schematic equivalent circuit in which the configuration of the excitation system in FIG. 1 is a single-machine infinite bus system, and FIG. 7 is a block diagram in which the single-machine infinite bus system is linearly approximated.

In the block diagram of FIG. 7, the angular frequency change Δω
If the phase of the internal induced voltage change △ Eq ′ matches the attenuation rate σ, the power fluctuation can be suppressed by:
It is necessary to make the phases of Δω and ΔEq 'equal. In addition,
The phase of Δf is equal to the phase of Δω. Here, the internal induced voltage Eq ′ is shown in the vector diagram of FIG. 6, and is obtained by (Equation 2).

[0030]

Eq ′ = Ei− (xd−xd ′) id where Ei = xad · If xad = xd−xlid = (Eq′−Ecosδ) / (xe + xd ′) xd: direct axis synchronous reactance xd ′ : Linear axis transient reactance xl: Armature leakage reactance In order to make the phases of Δω and △ Eq 'equal, from the variation △ Eq' of the internal induced voltage detected by the variation detecting circuit 21,
The phase detection circuit 28 detects the phase θ _{ΔEq ′} . at the same time,
The phase detection circuit 29 detects the phase θ _Δf from the frequency change Δf detected by the change detection circuit 22.

[0031] Next, the phase difference of the phase θ _{△ Eq 'and} the phase θ _{△ f △}
θ is obtained and input to the phase correction gain calculation circuit 30. The phase correction gain calculation circuit 33 sets the phase correction gain β to 0 if the phase difference Δθ is within a predetermined value (± φ), and to a predetermined functional relationship, for example, a value proportional to a constant k if the phase difference Δθ exceeds the predetermined value (numerical value). 3) and output through upper and lower limiters.

[0032]

Β = 0 (if; −φ ≦ △ θ ≦ φ) = k · △ θ (else) As is apparent from (Formula 3), the phase correction gain β is the difference between the frequency f and the internal induced voltage Eq ′. The phase difference △ θ is within a certain range (±
When it exceeds φ), it is a change for performing phase adjustment between the two.

The phase correction gain multiplication circuit 31 multiplies the phase correction gain β by the weight addition coefficient Kf ′ calculated based on the active power change ΔP, and calculates the weight addition coefficient Kf of the f gain adjustment circuit 11. Determined from (Equation 4).

[0034]

## EQU4 ## Kf = (1 + .beta.). Kf 'FIG. 8 is a vector diagram for explaining the phase adjustment by the PSS of this embodiment. FIG. 8A shows the state before adjustment, and FIG. 8B shows the state after adjustment. ing. As shown in the figure, in the AVR-Gen system (excitation system), the input value Pin of the active power P or the change △
Pin and the input value fin of the frequency f or the change thereof △
The fins have a 90 ° phase difference.

In order to increase the power fluctuation damping rate,
It is necessary to make the phase of the internal induced voltage Eq 'equal to the frequency f, but the output of the PSS is delayed by the AVR-Gen system, and the internal organic voltage Eq' has a phase difference of △ θ from the frequency f.

Then, for example, Kf is increased by the phase correction gain β determined by (Equation 3) so that the phases of △ f and △ Eq 'coincide with each other, as shown in FIG.
Ratio of Kp · △ Pin and Kf · △ fin (vector sum)
Is changed to determine the PSS output. That is, the lead angle of the PSS output with respect to Δf is determined by the phase correction gain β.

FIG. 9 shows an example of a vibration state identification means for identifying a fluctuating input signal. A predetermined input signal x is captured for four periods at a sampling period H (s), and a time-series signal x
(0) and, as when passing through the first stage of the sampling delay device Z ~ ^1-series signal x (1), and the time-series signal through the two-stage x (2),
From the four time series signals with the time series signal x (3) having passed through three stages,
The signal state is identified through a known operation. In this embodiment,
Using the active power change ΔPin as a time-series input signal,
The amplitude value A, the attenuation rate σ, and the frequency ω are calculated from the identification result. That is, the amplitude value detecting means 23, the attenuation rate detecting means 25, the frequency detecting means 6, and the like are realized.

According to such a PSS of the present embodiment, 90 ° is used based on the attenuation rate and the frequency fluctuation estimated from the system state.
Since the ratio of the gain of ΔP and the gain of Δf having different phases is dynamically controlled and the PSS output is determined so that the phases of Δω and ΔEq ′ become equal, the attenuation rate of the power fluctuation can be increased.
The dynamic stability of the VR-Gen system can be improved.

Next, a second embodiment of the present invention will be described.
FIG. 10 shows a PSS to which a weight addition coefficient limiter has been added. When an abnormality occurs in the input signal, or when an abnormality occurs in the state estimator 8, the weight addition coefficient calculation circuit 9, or the like, the weight addition coefficient calculation circuit 9 is used to prevent a sudden change in the weight addition coefficient. , An active power weight addition coefficient limiter 40 and a frequency weight addition coefficient limiter 4
1 is set.

The weight addition coefficient limiter calculates the weight addition coefficient K
When the absolute value | dK / dt | of the rate of change is equal to or smaller than the fixed value ε, the weight addition coefficient K is output as it is. On the other hand, when the absolute value of the rate of change is equal to or larger than ε, a value obtained by adding ε · Δt to the output of the self (weight addition coefficient limiter) one cycle before is output as the weight addition coefficient K.

In this embodiment, the output Kp of the weight addition coefficient calculation circuit 9 is given by (Equation 5), and the output Kp is given by (Equation 6)
Respectively, the rate of change is limited. Where si
gn (x) is a sign function, and sign (x) = 1 (x ≧
0) or -1 (x <0). Δt is a calculation cycle.

[0042]

| DKpi / dt | <ε1 Kpi = Kpi | dKpi / dt | ≧ ε1 Kpi = Kpi−1 + ε1 · Δt · sign (dKpi / dt)

[0043]

| DKfi / dt | <ε2 Kfi = Kfi | dKfi / dt | ≧ ε2 Kfi = Kfi−1 + ε2 · Δt · sign (dKfi / dt) According to the present embodiment, the rate of change of the weight addition coefficient K is Constant value ε
If there is a sudden change above, the current output value will be
Since the correction coefficient is limited to the value obtained by adding Δt, the correction coefficient can be prevented from suddenly changing or becoming excessive even when the input signal is abnormal, and the PSS output can be stably maintained.

In the above embodiment, the limiters 40, 41
May be configured to simply limit the upper and lower limits to prevent the addition coefficient from becoming excessive, or to limit both the rate of change and the upper and lower limits.

Next, a third embodiment of the present invention will be described.
FIG. 11 shows a circuit for switching the weight addition coefficient when a system fault occurs. The active power weighting addition coefficient switching circuit 42 and the frequency weighting addition coefficient switching circuit 43 switch the input coefficient K depending on whether the system is normal or abnormal. In the normal state, the input coefficient is output as it is, and in the event of an abnormality in which an accident detection signal is output from the system accident detection device 24, the weight addition coefficient one cycle before is output as it is, or a predetermined value suitable for system abnormality is output. Output.

According to this, it is possible to prevent the weighted addition coefficient from becoming an abnormal value due to the imbalance of the input signal due to the occurrence of a system fault, and to secure a stable PSS operation. The limiter of the second embodiment can have the switching function of the present embodiment.

[0047]

According to the present invention, the active power and the frequency weighting addition coefficient or the ratio thereof are dynamically controlled based on the measurement of the system attenuation factor and the frequency fluctuation state, so that the operation state of the system can be changed. It has the effect of adapting and improving the dynamic stability.

According to the present invention, it is possible to prevent the weight addition coefficient from becoming excessive or abrupt when an input signal abnormality or a system failure occurs,
There is an effect that a stable operation of the PSS can be maintained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a power system stabilizer (PSS) of the present invention.

FIG. 2 is a configuration diagram of a conventional power system stabilization device.

FIG. 3 is a configuration diagram of a state estimator and a weight addition coefficient calculation circuit of the present embodiment.

FIG. 4 is a waveform chart showing a temporal change and an attenuation rate of an active power change (power fluctuation).

FIG. 5 is an equivalent circuit diagram in which the configuration of the excitation system (AVR-Gen system) is modeled as a single-machine infinite bus system.

FIG. 6 is a vector diagram illustrating an internal induced voltage Eq ′.

FIG. 7 is a block diagram obtained by linearly approximating the model of FIG. 5;

FIG. 8 shows the power P from the active power adjustment signal and the frequency adjustment signal.
FIG. 4 is a vector diagram for obtaining an SS output.

FIG. 9 is a functional block diagram of the vibration state identification device.

FIG. 10 shows a second embodiment, and is a configuration diagram of a power system stabilizing device to which a weight addition coefficient change rate limiter is added.

FIG. 11 is a configuration diagram of a power system stabilizing apparatus according to a third embodiment, to which a weight addition coefficient switching circuit based on system fault detection is added.

[Explanation of symbols]

1: Synchronous generator, 2: Exciter, 3: PT, 4: CT, 5
... active power detection device, 6 ... frequency detection device, 7 ... internal induced voltage detection circuit, 8 ... state estimator (decay rate and phase difference detector), 9 ... weight addition coefficient calculation circuit, 10 ... P gain adjustment circuit, 11: f gain adjustment circuit, 12: DC component removal circuit, 17: PSS output limiter, 18: AVR signal addition circuit, 20, 21, 22 ... change detection circuit, 23 ... amplitude value detection circuit, 24 ... attenuation rate Detector, 27: Weight addition coefficient adder / subtractor, 28, 29: Phase detector, 30: Phase correction gain calculation circuit, 31: Phase correction gain multiplication circuit, 40,
41 ... weight addition coefficient change rate limiter, 42, 43 ... weight addition coefficient switching circuit, 44 ... system fault detection device.

Continuation of front page (56) References JP-A-1-129800 (JP, A) JP-A-1-308198 (JP, A) JP-A-4-165999 (JP, A) JP-A-5-122998 (JP) JP-A-61-280714 (JP, A) JP-A-59-73000 (JP, A) JP-A-60-139132 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H02J 3/24 H02P 9/14

Claims (11)

(57) [Claims] 1. A corrects the gain and phase in response to the active power and system frequency of the synchronous generator, by adjusting the exciter of the synchronous generator and further through the automatic voltage regulator <br/> equipment, In a power system stabilizing device for stabilizing a power system, an attenuation rate of power fluctuation is obtained from a change amount of the active power, an active power gain is updated according to the attenuation rate, and the automatic voltage adjustment is performed from a change amount of the system frequency. Find the phase difference due to the delay of the device , update the phase correction gain according to the phase difference,
A multiplication value of the real power or a temporal change in the real power and the real power gain, and the system frequency or the system frequency;
A control method by a power system stabilizing device , wherein a vector sum of a temporal change in number and a multiplied value of the phase correction gain is input to the automatic voltage regulator . 2. The power system stabilization according to claim 1, wherein the correction of the active power gain is performed by multiplying or adding a predetermined value to the gain before updating when the attenuation rate is equal to or less than a reference attenuation rate. Control method by device. 3. The correction of the phase correction gain according to claim 1, wherein, when the attenuation rate is equal to or less than a reference attenuation rate, the gain before updating is multiplied or added by a predetermined value, and the automatic voltage adjustment is performed. When the phase difference due to the delay of the device exceeds a predetermined range including 0 in the range, a value that increases positively or negatively according to the phase difference is added. 4. The phase difference according to claim 3, wherein the phase difference due to the delay of the automatic voltage regulator is a difference between the system frequency or the phase of the rotation speed of the synchronous generator and the phase of the internal induced voltage of the excitation device. A control method using a power system stabilizing device characterized by the above-mentioned. 5. corrects the gain and phase in response to the active power and system frequency of the synchronous generator, by adjusting the exciter of the synchronous generator and further through the automatic voltage regulator <br/> equipment, A power system stabilizing device for stabilizing a power system, comprising: a 90- degree phase based on a power fluctuation damping rate and a frequency variation estimated from a state based on an active power and a frequency of the power system and an internal induced voltage of the excitation device. Different active power or have
Active power gain and frequency multiplied by the temporal change of active power
Or by dynamically changing the temporal variation in Jozu that position phase correction gain ratio of the frequency, output of the power system stabilizer as phase equals the internal induced voltage and the frequency <br/> A control method by a power system stabilizing device, characterized by determining a force. 6. The method according to claim 1, wherein the active power gain and the phase correction gain are set to predetermined limits.
A control method by a power system stabilizing device, wherein the control method is updated within a value range . 7. The control method according to claim 6, wherein the predetermined limit value defines a maximum value or a maximum change rate of the active power gain and / or the phase correction gain. . 8. provided excitation system of the automatic voltage regulator for adjusting the exciter of the synchronous generator to output power to the grid,
In a power system stabilizing device for stabilizing a power system by performing gain and phase correction according to the active power and system frequency of the synchronous generator, active power means and frequency detecting means for detecting active power and frequency from the system Internal induced voltage detecting means for obtaining an internal induced voltage of the excitation device, active power adjusting means for multiplying the detected active power by an active power gain, and frequency gain adjusting means for multiplying the detected frequency by a phase correction gain, An adding means for adding outputs of the active power adjusting means and the frequency gain adjusting means, and a DC component removing means for detecting a change in the output and outputting the detected output to the automatic voltage adjusting device; and a power fluctuation from the active power change. The attenuation rate, the change in the system frequency and the change in the internal induced voltage,
State estimating means for obtaining a phase difference due to a delay of the automatic voltage adjusting device ; and weight addition coefficient calculating means for updating the active power gain according to the attenuation rate and the phase correction gain according to the attenuation rate and the phase difference. A power system stabilizing device, comprising: 9. The power system stabilizing device according to claim 8, wherein the weighting addition coefficient calculating means includes a limiter for performing a predetermined limit on the active power gain and the phase correction gain. 10. The method according to claim 9, wherein the limiter does not update the active power gain and the phase correction gain during a period when a signal of each phase is imbalanced after the occurrence of a system fault. Power system stabilizer. 11. The electric power system according to claim 8, 9 or 10, wherein the state estimating means includes a vibration state identifying means for inputting the time series signal of the active power and identifying the damping rate. Stabilizer.