JPS62135299A - Generator control system - Google Patents

Abstract

PURPOSE:To improve transient and static stability by adding an output from a controller conducting multivariable feedback control to the manipulated variables of each system as the quantities of correction on the basis of various informations observed from a generator and a turbine. CONSTITUTION:A multivariable controller 1 arithmetic operates optimum feedback gains on the basis of generator voltage Vt(K), a generator output Pe(K), field flux phif(K), turbine angular-frequency omega(K), a generator phase angle delta(K) and turbine opening Pm(K), and arithmetically operates a field manipulated variable Ue(K) and a governing manipulated variable Ug(K) with a multivariable control theory. The field manipulated variable Ve(K) is added to outputs from an automatic voltage regulator 4 and a system stabilizer 5 as correction signals. On the other hand, the governing manipulated variable Ug(K) is added to an output from a governor 7 as a correction signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a generator control method for improving the damping (elastic restoring IT) characteristics of a generator excitation system and a turbine regulating system in a power plant.

[Conventional technology]

FIG. 2 is a schematic diagram showing a conventional generator control system. In the figure, 11 is a generator, 12 is a turbine, 13 is an excitation system, 14 is an automatic voltage regulator (AVR),
Reference numeral 15 indicates a speed control system (governor system), 16 an input valve, and 17 a system stabilizing device (PSS').

That is, conventionally, the AVR 14 performs control to keep the voltage constant, and the governor system performs control to keep the turbine rotation speed (frequency) constant. In such systems, it is known that fluctuations in the generator output voltage and power associated with so-called negative braking phenomena are mainly caused by the automatic voltage regulator 14 having a high gain, and for this reason, the system stabilizer (PSS) 17 is provided auxiliary. This PS
817 extracts at least one of the deviations of the generator output, turbine rotation speed, generator internal phase difference angle, etc., and provides this as a correction signal to the AVR 14 via a phase adjuster (not shown), thereby suppressing oscillation. It is something.

In addition to the above, if a serious failure such as a three-phase short circuit occurs between the generator and the power system to which it is connected, a control method is developed that detects this and rapidly controls the turbine output in the direction of decrease. By adopting this method, we aim to improve stability. Furthermore, when a short-circuit accident occurs on the transmission end bus of a power plant, a braking resistor is temporarily applied to absorb the acceleration energy stored in the turbine generator shaft due to the accident and take measures to prevent step-out. This is intended to enhance transient stability.

[Problem that the invention seeks to solve]

However, regarding the PSS mentioned above, when the generator output (power) fluctuates in response to a disturbance occurring on the grid side, for example, the fluctuation is extracted by the PSS, but this fluctuation natural frequency is the generator output at that time. Since it changes significantly depending on the state and the magnitude of the external reactance beyond the generator terminal, there is a problem in that the phase characteristics of the phase adjuster change and the oscillation suppressing effect decreases.

Turbine high-speed valve control is performed to absorb acceleration energy stored in the generator shaft in the event of a failure, etc., but in order to effectively perform this, it is necessary to simultaneously control the main control valve and intercept valve (not shown) at high speed. After closing control, open control is necessary to return to the original output, but the opening time of the intercept valve is generally long, 5 to 10 seconds, which not only causes a decrease in frequency due to a decrease in turbine output. , which increases the boiler outlet pressure and causes unnecessary safety valve operation.

Furthermore, the braking resistor used to enhance transient stability must have a capacity equivalent to 50 to 100% of the power plant capacity, and must be turned on at high speed, which is an economic burden. There is a problem of being forced to make additional capital investment.

Therefore, an object of the present invention is to provide a generator control method that can solve the above problems and exhibit excellent control performance.

[Means for solving problems]

Control calculations are performed based on multivariable control theory based on the generator motor Ti system that controls the generator output voltage, the turbine speed governor system that controls the turbine rotation speed, and various observed quantities obtained from the generator and turbine. A multi-variable control device is provided which individually determines optimum feedback gains and outputs manipulated variables corresponding to each of the systems.

[Effect]

By adding the manipulated variable from the multivariable control device as a correction amount to the manipulated output of each unit, voltage and power fluctuations in particular are effectively suppressed and stability is improved.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 is a multivariable control device that calculates the optimal feedback gain based on various observed quantities obtained from the generator and turbine and performs control based on multivariable control theory, and is illustrated in an easy-to-understand diagram. . Also, 2
1.22 is a band pass filter, 31.32 is a limiter, 4 is an automatic voltage regulator (AVR), 5 is a system stabilization device (PSS), 6 is a firing angle regulator of the Cyrisk exciter, and 7 is a speed governor. 8 is a turbine opening adjuster, 4 to 6 form an existing generator excitation system, and 7 and 8 form an existing turbine speed control system.

First, the multivariable control device 1 will be explained. In addition, this
The meaning of each symbol used in is as follows.

■Yo: Voltage setting value vLikl: Generator output voltage Ps at time (k):
Output setting value P,. >: Generator output Φ at time (k). ,: Field magnetic flux Φ at time (k). -n: Field magnetic flux ωn at time (kl): Turbine angular frequency ω at time (k). -n:
Turbine angular frequency δ(k) at time (kl) = Generator phase difference angle δn-u at time (k): Generator phase difference angle p at time (k1)
aww,. : Turbine opening degree Pffin-+ at time (k)
+: Turbine opening degree u−n+ at the time of (k 1 )
: Field operation amount us(k-H: (k) at time (k)
1) Field of time 6n Manipulated amount uq (k,: Speed-governing manipulated variable u at time (k), (k-11: Speed-governing manipulated variable at time (k 1 ), that is, sampling control with a constant period Δτ The current value of each quantity is shown with a suffix k, and the previous value is shown with a suffix (k-1). 26 is a gain determined individually.

Here, the excitation operation amount u of the voltage control deviation V, Vtn,
a (For the effect on kl, at 61 hours,
ue+k) = uan+-n + Kz (Vs-
= Vtn++) That is, Δuan+=Kz (Vi Vtn+). In other words, the voltage control deviation has an integral effect on the excitation system operation amount. Also, power control deviation P.

The effect of Pan++ on the governor operation amount ug(k) is
Similarly to the above, the following relationship is established, which also shows an integral effect. Furthermore, voltage control deviation becomes gain! I is related to the manipulated variable of the governor system, and the power control deviation is related to the manipulated variable of the excitation system at gain 1□, and each control deviation has an integral effect on the manipulated variable of the other party.

In addition, various quantities Φ1, which were selected in advance as the main influencing quantities on the dynamic behavior of the generator, ω, δ and P,.

On the other hand, the deviation between the measured or estimated current value and the previous value is 1 for each gain KI3~.
6 is involved in the excitation system operation amount, and on the other hand, 23 to 2& are involved in the governor system operation amount in the gain, respectively. In this case, for example, focusing on the field magnetic flux Φ, and examining its effect on the excitation system operation amount, in 61 hours, u, (, l, -u, (k-I, +) is 8 ．(Φ, ., −Φ
ftk-11) Therefore, Δuati++=+3°ΔΦt (k)-'-u a
<kl = K +xΦf (k). In other words,
The field magnetic flux shows a proportional effect to the excitation system operation amount. In this way, each influence amount exhibits a proportional effect on the manipulated variable of each excitation system and the manipulated variable of the governor system.

Here, set the individual gains to ~Kl& and 21 to 2.
In order to optimally set &, for example, +qz (P t P ann)”+q3 (u
lltkl us. −3,)2”qa (tl(1
(kl ug□-0)2), and the weighting coefficient q1
After setting ~q4, a method may be used in which the gain is determined so that the value of this index J becomes the minimum value. In this case, what is needed is a dynamic model of the controlled object, and the index J is considered based on a model in which a shape DI representing each control deviation is added to this model. According to the control principle as described above, integral control is performed on the voltage and power control deviations, and as a result, the final steady-state deviation becomes zero. Therefore, the dynamic model of the controlled object may be a simple model, which makes determining the control gain practically simple. In this way, by simply setting the weighting coefficients q, ~q, the optimum control gain can be determined through automatic calculation, and control with excellent dynamic characteristics can be realized.

Now, among the manipulated variables extracted in this way, the field manipulated variable U. After only the variation thereof is extracted by the bandpass filter 21, it is limited by the limiter 31 as necessary, and is given to the firing angle adjuster 6 as a correction control signal Δu a fkl. Therefore, the generator excitation system is A
Control is performed by adding a correction control signal to each output of VR4 and PSS5.

-4, iP] 1lJi produced it u , axis, only the variation thereof is limited and taken out by the bandpass filter 22 and limiter 32 (see ΔU, .), and this is added to the output of the speed governor 7. The speed governing system is controlled.

That is, the control performance is improved by adding the manipulated variable from the multivariable control device as a correction control signal to each of the generator excitation system and the turbine speed control system. Therefore, the present invention is suitable for use in cases where already installed equipment is effectively utilized.

〔Effect of the invention〕

According to this invention, a control device is provided that performs multivariable feedback control based on various information observed from the generator and the turbine, and the output is controlled by adding the output as a correction amount to the manipulated variable of each unit. This provides the advantage of significantly improved transient and steady-state stability.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, and Fig. 2 is a schematic diagram showing a conventional example of a power plant control system. Automatic voltage regulator (AVR), 5.17...System stabilizer (PS)
S), 6... Firing angle adjuster, 7... Speed governor, 8...
・Opening adjuster, 11... Generator, 12... Turbine, 13... Excitation system, 15... Governor system, 16...
Input valve, '21゜22...Band pass filter, 31
．． 32...Limiter.

Claims (1)

[Claims] Control calculations are performed based on multivariable control theory based on the generator excitation system that controls the generator output voltage, the turbine governor system that controls the turbine rotation speed, and various observed quantities obtained from the generator and turbine. A multi-variable control device that individually determines an optimum feedback gain and outputs a manipulated variable corresponding to each system, and performs control by adding the manipulated variable from the control device as a correction control signal to the manipulated output of each system. A generator control method characterized by: