JPH0345995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power system stabilizer (PSS) used in an excitation device for a synchronous generator.

[Conventional technology]

FIG. 4 is a block diagram of a general excitation system incorporating a conventional PSS as disclosed in, for example, Japanese Patent Publication No. 53-44204.

In the figure, 1 is the input terminal for the deviation of the generator terminal voltage from the reference value, 2 is the PSS, 3 is the input terminal of PSS2, 4 is the damping circuit, and 5 is the sum of the deviation from input terminal 1 and the output of PSS2. Damping circuit 4
6 is a regulator that controls an excitation device 7 with the output of this addition circuit 5; 7 is an excitation device that is controlled by this regulator 6 and supplies the field voltage of a generator (not shown). It is. 2a
is a filter circuit for determining the response range of the PSS 2 to the input signal 3, and usually has a transfer function characteristic of the form T _R S/1+T _R S 1/1+T _H S. 2b This is a part that corrects the time delay of the regulator 6, excitation device 7, generator, etc., and is usually a lead/lag circuit expressed in the form K ₁ 1+T ₁₂ S/1+T ₁₁ S. 2c is
This is a limiter that limits the output signal of PSS2 to an appropriate signal level considering the entire excitation system shown in FIG.

The input signals of PSS2 are usually the rotation speed deviation of the generator rotor, the frequency deviation of the generator terminal voltage,
The output deviation of the generator is used.

Next, the operation will be explained. When the generator terminal voltage deviates from the reference value, a deviation signal is applied to the input terminal 1, and this deviation signal is amplified by the regulator 6 and input to the excitation device 7. It is further amplified in the excitation device 7, supplied to the field of the generator, and controlled so as to return the deviation of the generator terminal voltage from the reference value to zero. The damping circuit 7 is for stabilizing the voltage control described above.

The above is the function of a so-called general automatic voltage regulator (hereinafter referred to as AVR), and the auxiliary signal (for example, rotation speed deviation of the generator rotor, etc.) is appropriately amplified in the adder circuit 5 of the excitation system. PSS2 is a control device that improves the stability of the power system by correcting and adding .

Now, consider a PSS whose input is the rotation speed of the generator rotor. The detected rotational speed deviation is applied to input terminal 3 of the PSS. This signal has its direct current component and high frequency removed by a filter 2a, and is applied to a correction circuit 2b, where it is appropriately amplified and phase corrected. This signal is limited by the limiter 2c to a signal level below that appropriate for the excitation system, and is applied to the adder circuit 5, where the output voltage of the excitation device 7 is controlled so as to suppress the fluctuation of the generator rotor.

Next, the principle of PSS will be explained. FIG. 5 is a block diagram linearly approximating the oscillation of a single-machine infinite system generator as shown in, for example, Electric Kyodo Research Vol. 34, No. 5. In the figure, K ₁ is the synchronization torque system generated by a generator with constant field linkage magnetic flux, and K ₁ ′ is
The synchronized torque series generated by the AVR, K ₁ ″, is
D is the synchronized torque series generated by PSS, D is the braking torque series generated by a generator with constant field linkage flux, D′ is the braking torque series generated by AVR,
D″ indicates the braking torque series generated by PSS.

Generally, when the power factor is close to 1.0 and the phase angle θ becomes large, D' tends to take a negative value. Especially in high-speed response, high-gain AVRs, D+ may occur in some cases.
D′ becomes negative, and steady state stability may not be maintained due to insufficient braking force. In this case, by adding PSS, a braking force D'' is generated to stabilize the vehicle.

FIG. 6 is an explanatory diagram showing these aspects. PSS improves braking force by generating a braking force D″ in the opposite direction to cancel the negative braking force D′ generated by the high-speed response, high-gain AVR.However,
PSS is not intended to improve synchronization ability,
K ₁ ″ may be very small or even slightly negative in some cases.

[Problem that the invention seeks to solve]

Since the conventional PSS is configured as described above, it is not possible to improve the synchronization power necessary in the transient region where the generator is shaken greatly immediately after an accident occurs in the power system, and therefore, the transient stability is There were drawbacks such as the inability to improve performance.

This invention was made in order to solve the above-mentioned problems.In the transient region where the generator oscillates greatly, the synchronizing force can be sufficiently increased to improve the transient stability, and the oscillation of the generator can be reduced slightly. The object of the present invention is to obtain a power system stabilizing device that can sufficiently increase the braking force in the reduced steady-state region to improve steady-state stability.

[Means for solving problems]

The power system stabilizing device according to the present invention improves the braking force using the first PSS set to improve the synchronization force using the generator rotation speed or the grid frequency as the input signal and the generator output as the input signal. The second
PSS, and the magnitude of the oscillation of the generator is determined, and the gain elements of the first PSS and the second PSS are changed.

[Effect]

In the PSS of this invention, the magnitude of generator oscillation is determined by a system oscillation determination circuit, and in a transient region where the oscillation is large, the gain element of the first PSS, which is set to improve the synchronization power, is increased, and the 2 of
The second control system is designed to reduce the PSS gain element and improve braking force in the steady state region where vibration is small.
The gain element of the PSS is increased, the gain element of the first PSS is decreased, and the output of this PSS is added as an auxiliary signal to the excitation system to improve the transient stability of the generator and the damping of vibration. Controls the output voltage of the exciter.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 1, 2 is the second PSS set to improve the braking force, 8 is the first PSS set to improve the synchronization force, and 9 is the one that determines the magnitude of generator oscillation. System oscillation determination circuit, 10 is an input terminal of the system oscillation determination circuit 9, 3 is an input signal of the first PSS 2, a generator output signal, 11 is an input terminal of the second PSS
8, which is a generator rotational speed signal or a system frequency signal.

8a is a filter circuit for determining the response range for input signal 3 of PSS8, and is normally
It has a transfer function characteristic of the form T _R · S/1 + T _R · S1/1 + T _H S. 8b is a part that corrects the time delay of the regulator 6, excitation device, generator, etc., and is usually K ₂
It is a lead/lag circuit expressed in the form 1+T ₂₂ S/1+T ₂₁ S. 8c is a limiter that limits the output signal of the PSS 8 to an appropriate signal level considering the entire excitation system shown in FIG. Note that the lead/lag circuit 2b is a first phase correction circuit, and the lead/lag circuit 8b is a second phase correction circuit.

As input signals to the system oscillation determination circuit 9, a rotation speed deviation of a generator rotor, a generator output deviation, a generator terminal voltage deviation, etc. are used.

In addition, PSS2, which is set to improve the braking force, has a torque characteristic as shown in Fig. 6, and a large positive D'' is generated in the second phase correction circuit 2b. The settled PSS8 is the second
It has a torque characteristic as shown in the figure, and a relatively large positive K ₁ ″ is generated in the first phase correction circuit 8b.

Next, the operation will be explained. Now consider the case where the rotation speed deviation of the generator is input to the input terminal 10 of the system oscillation determination circuit 9 and the input terminal 11 of the first PSS 8. When an accident occurs in the power system, the rotational speed deviation Δω of the generator changes as shown in FIG. During normal operation, the generator rotational speed deviation Δω is almost zero,
In this case, a second PSS to improve braking power
The gain element of the second PSS 8 is made large, and the gain element of the first PSS 8 for improving the synchronization power is made small.

When a system fault occurs, Δω changes as shown in Fig. 3. This is captured by the system oscillation determination circuit 9, and as soon as the fault occurs, the gain element of the second PSS 2 is reduced, and the gain element of the first PSS 8 is reduced. Change it to make it bigger. This state continues until the peak value of Δω exceeds a certain value, and when it reaches a certain value, each gain element is returned to its original value.

The outputs of the first PSS2 and the second PSS8 are added to the adder circuit 5 as auxiliary signals for the excitation system. This addition is so-called vector synthesis, and immediately after a system fault occurs, it is the first step to improve synchronization power.
The vector component of PSS8 becomes large, and the vector component of second PSS2, which improves the braking force during steady operation, becomes large.

Note that in the above embodiment, the transient region and steady state region of the generator's oscillation were determined based on the magnitude of the rotational speed deviation. The determination may be made based on the size of the .

Further, in the above embodiment, each gain element is switched in two stages depending on the rotation speed deviation, but it may be switched more finely in n stages, and the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the PSS is provided with a first PSS for improving synchronization power, a second PSS for improving braking, and a system oscillation determination circuit for detecting the amount of oscillation of the generator. The second in the steady state region where the amount is small
The gain of the PSS of 1 is made large, and the gain of the PSS of 1 is made large in the transient region where the amount of oscillation is large, which has the effect of improving steady-state stability and also improving transient stability. is obtained.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a general excitation system including a PSS according to an embodiment of the present invention, Fig. 2 is a vector diagram explaining the torque characteristics of the PSS set to improve synchronization power, and Fig. 3 is a waveform diagram showing the oscillation of the generator, Fig. 4 is a configuration diagram of a general excitation system including a conventional PSS, and Fig. 5 is a block diagram that linearly approximates the oscillation of a single-engine infinite generator system. The diagram and FIG. 6 are vector diagrams illustrating the torque characteristics of a conventional PSS that is set to improve braking force. 1 is an input terminal for the deviation signal between the generator terminal voltage and the reference value, and 2 is the second terminal set to improve the braking force.
3 is the input terminal of the first PSS, 4 is the damping circuit, 5 is the excitation system addition circuit, 6 is the regulator, 7 is the excitation device, 8 is the first PSS set to improve the synchronization power. PSS, 9 is a system oscillation determination circuit for determining the magnitude of generator oscillation, 10 is an input terminal of the system oscillation determination circuit, and 11 is an input terminal of the first PSS. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Generation output of synchronous generator, frequency of terminal voltage,
It is obtained by using any of the rotational speeds of the rotor as an input signal and passing this input signal sequentially through a filter circuit having predetermined transfer function characteristics, a first phase correction circuit with a large synchronization torque coefficient, and a limiter circuit. a first power system stabilizing device that adds an output signal to an input signal of an automatic voltage regulator that controls an excitation device of the synchronous generator; a second power system stabilizing device that adds an output signal obtained by sequentially passing through a filter circuit having a characteristic, a second phase correction circuit having a large braking torque coefficient, and a limiter circuit to the input signal of the automatic voltage regulator; , using any of the power generation output of the synchronous generator, the frequency of the terminal voltage, and the rotor as an input signal, detecting changes in this input signal, and detecting the steady state region where the change in the input signal is small. The braking force of the synchronous generator is increased by controlling the gain of the phase correction circuit of
A power system stabilizing device comprising: a power system oscillation determination circuit configured to increase the synchronization power of the synchronous generator by controlling the gain of the phase correction circuit to be increased.