JP3345773B2 - Plant automatic controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic plant control apparatus, and more particularly, to a method for compensating frequency fluctuations in a power plant in which a turbine is rotated by steam generated from a boiler and a generator is rotated by the turbine. Related to automatic plant automatic control devices.

[0002]

2. Description of the Related Art Conventionally, in a power plant using thermal power, a configuration has been adopted in which steam generated from a boiler is supplied to a turbine via a turbine control valve, and a generator is driven by the rotational energy of the turbine. An automatic plant control device is provided to control the output of the turbine, and a turbine control device is provided to control the turbine control valve. In order to compensate for frequency fluctuations in the power system, the automatic plant control device performs control to correct the generator output target value, the turbine control device performs constant frequency control, and the control devices share the frequency fluctuation. Is compensated. That is, the plant automatic controller adds the generator output correction value set in accordance with the deviation between the rated frequency of the power system and the actual frequency of the power system to the generator output command for the generator, and A request signal (MWD) is generated, and based on the generator output request signal, water, fuel and air, which are boiler input amounts, are controlled, and a deviation between the generator output request signal and the actual output of the generator is calculated. A proportional / integral operation is performed to generate a turbine control valve operation command, and the turbine control valve operation command is output to the turbine control device. On the other hand, in the turbine control device, turbine steam is generated based on a frequency signal generated according to a deviation between the rated frequency of the power system and the actual frequency of the power system and a turbine control valve operation command generated by the automatic plant control device. A steam amount control signal for controlling the amount is generated, and the frequency is controlled to be constant by operating the turbine control valve according to the steam amount control signal. Here, in the automatic plant control device, when correcting the generator output to the target value, a method of setting the correction amount to 0 (this range is called a dead zone) in a range where the frequency fluctuates to some extent is adopted. This is because even if a correction due to a slight frequency variation is added to the generator output request signal, the amount of water, fuel, and air on the boiler side cannot follow the generator output request signal, and the factor of disturbance increases. .

[0003] Further, in the constant frequency control in the turbine control device, as described in Japanese Patent Application Laid-Open No. 60-95104, a turbine speed error is provided with a so-called dead zone against frequency fluctuation, and the turbine speed is transiently corrected. To prevent the life of the turbine from being shortened.

[0004]

In the prior art, when compensating for frequency fluctuations in a generator plant, control for correcting the generator output target value is performed by an automatic plant control device, and constant frequency control is performed by a turbine control device. It is supposed to do. However, in the conventional plant automatic control device, since the turbine control valve operation command is generated based on the deviation between the generator output request signal and the actual generator output, depending on the value of the turbine control valve operation command,
The control opposite to the control target of the turbine controller (when the frequency signal generated according to the deviation between the rated frequency and the actual frequency indicates a value in the direction to close the turbine control valve, the value of the turbine control valve operation command is When the value indicates the direction in which the turbine control valve is to be opened, the pullback phenomenon may occur. Here, the frequency fluctuation means that when the generator rotates 3000 times per minute and an alternating current having a frequency of 50 Hz is generated, the number of rotations of the generator is 1 for example.
It means when the frequency of the system deviates from 50 Hz due to increase or decrease in rotation.

More specifically, the prior art has the following problems.

(1) When the frequency fluctuates, a generator output correction value set according to the deviation between the rated frequency of the power system and the actual frequency of the power system is determined according to a correction program. Is a theoretical value, and it is necessary to adjust the generator output correction value for each plant.
Further, it is necessary to adjust the generator output correction value in accordance with the change in the actual correction amount due to the characteristics of the turbine control valve.

(2) In the correction program, a dead zone is set for frequency fluctuation. It is desirable that the width of the dead zone be as wide as possible for water supply, fuel, and air control, which is control on the boiler side. In order to contribute to the stabilization of the frequency, it is desirable that the frequency be as narrow as possible. This is because control on the turbine side has sensitivity and speed that can follow the correction due to slight frequency fluctuation, but cannot be followed by control on the boiler side.

As described above, in the conventional plant automatic control device, the generator output command is corrected based on the generator output correction value set according to the correction program to generate a generator output request signal, and the generator output request signal is generated. The turbine control valve operation command is generated based on the deviation between the signal and the actual generator output.However, the value of the correction program does not sufficiently match the actual plant, and the pullback phenomenon may occur depending on the frequency fluctuation. . When the width of the dead zone of the correction program is set according to the turbine control side, the turbine control valve operation command to the turbine control side has an appropriate value, but this value is a target value for turbine control and The steam required to adjust the rotation speed of the machine is insufficient due to the response delay of the boiler control. Also in this case, the turbine control valve operation command executes the pull-back control for the turbine control system.

An object of the present invention is to provide an automatic plant control apparatus, a generator plant control system, and a power plant capable of giving priority to frequency control by a turbine control system by restricting control by a turbine control valve operation command depending on frequency fluctuations. An object of the present invention is to provide a frequency variation compensation method.

[0010]

To achieve the above object, the present invention provides a generator output request signal for controlling the output of a boiler based on a generator output command to a generator connected to a power system. Generator output request signal generating means for generating a generator output request signal generated by the generator output request signal generation means and a turbine control valve operation command for generating a turbine control valve operation command according to a deviation between the generator output request signal and the actual output of the generator. Valve operation command generation means, wherein the turbine control valve operation command generation means is configured to control the turbine based on a frequency signal according to a deviation between the rated frequency of the power system and the actual frequency of the power system and a turbine control valve operation command. The turbine control system that controls the amount of steam is allowed to output the turbine control valve operation command only when the actual frequency value of the generator is within a set value range. The in actual frequency variation value of the frequency is out of the range of the set values of the generator is obtained by constituting the plant automatic control device formed by limiting the output of the turbine governor valve operation command to said turbine control system.

In configuring the automatic plant control apparatus, the generator output request signal generating means includes a generator output correction value set according to a deviation between the rated frequency of the power system and the actual frequency of the power system. It can also function to generate a generator output request signal for controlling the output of the boiler based on a generator output command for the generator connected to the power system.

When the automatic plant control device is constructed, when the generator output command is a command for forcibly changing the generator output, the turbine control valve operation command generating means is provided with a frequency variation. In addition, a function of allowing the output of the turbine control valve operation command can be added.

According to the present invention, a generator output request signal for controlling the output of a boiler is generated based on a generator output command to a generator connected to a power system. A plant automatic control device that generates a turbine control valve operation command according to a deviation from the actual output of the plant, a frequency signal generated according to a deviation between the rated frequency of the power system and the actual frequency of the power system, and a plant automatic control device. A turbine control device that generates a steam amount control signal for controlling a steam amount to the turbine based on a turbine control valve operation command generated by the control device, wherein the automatic plant control device is an actual generator of the generator. Only when the value of the frequency is within the set value range, the output of the turbine control valve operation command is allowed, and the actual frequency value of the generator is out of the set value range. At the time the frequency variation is obtained by constituting the power plant control system comprising limiting the output of the turbine governor valve operation command.

According to the present invention, a generator output request signal for controlling the output of a boiler is generated based on a generator output command for a generator connected to a power system. A turbine control valve operation command is generated according to a deviation from the actual output of the machine, and based on a frequency signal and a turbine control valve operation command according to a deviation between the rated frequency of the power system and the actual frequency of the power system. For a turbine control system for controlling the amount of steam to the turbine, the output of the turbine control valve operation command is permitted only when the actual frequency value of the generator is within a set value range. A frequency fluctuation compensation method in a power plant for limiting the output of the turbine control valve operation command to the turbine control system when the actual frequency value of the power supply deviates from a set value range. One in which was adopted.

When the above-mentioned frequency fluctuation compensation method is adopted, when generating the generator output request signal, the generator output correction is set according to the deviation between the rated frequency of the power system and the actual frequency of the power system. A method of generating a generator output request signal for controlling the output of the boiler based on the value and a generator output command value for the generator connected to the power system can be employed. Further, when the generator output command is a command for forcibly changing the generator output, a direction allowing the output of the turbine control valve operation command can be adopted regardless of the frequency fluctuation.

According to the above means, the output of the turbine control valve operation command is permitted to the turbine control system only when the actual frequency of the generator is within the range of the set value. When the frequency is out of the range of the set value, the output of the turbine control valve operation command is limited to the turbine control system when the frequency is out of the set value range, preventing the pullback phenomenon caused by the turbine control valve operation command due to the frequency change. The output frequency of the generator can be stably controlled by the turbine control system.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a thermal power plant control system showing one embodiment of the present invention, FIG. 2 is a configuration diagram of a correction program, FIG. 3 is a block configuration diagram of a correction circuit, and FIG.
1 is an overall configuration diagram of a thermal power plant.

As shown in FIG. 4, the thermal power plant
Boiler 1 that generates steam when supplied with water, fuel and air
0, the steam generated from the boiler 10 is
And a generator 16 for converting the rotational energy of the turbine 14 into electricity. A plant automatic control for controlling the output of the boiler 10 is provided. An apparatus 18 is provided, and a turbine control apparatus 20 for operating the turbine control valve 12 to control the rotation speed of the turbine 14 is provided.

The plant automatic control device 18 generates a generator output request signal (MWD) and a turbine control valve operation command based on the generator output command, and based on the generator output request signal, calculates the input amount of the boiler 10 based on the generator output request signal. While controlling water, fuel, and air to match the amount of power to be generated,
A turbine control valve operation command serving as an index of turbine control by the turbine control device 20 is generated.

Specifically, the plant automatic control device 18
As shown in FIG. 1, a generator output command generator 22, a change rate limiter 24, a frequency detector 26, a function generator 28,
Adder 30, upper and lower limiter 32, generator output detector 3
4, subtractor 36, limiting circuit 38, proportional / integral calculator 40
It is provided with.

The generator output command generator 22 generates a generator output command for the generator 16 connected to the power system in accordance with the amount of power to be generated, and outputs the generator output command to the change rate limiter 24. It has become. The generator output command input to the change rate controller 24 is
After the rate of change is limited, the generator output target value is input to the adder 30 as a signal. A signal according to the generator output correction value is input to the adder 30 from the function generator 28. The function generator 28 is provided with a correction program as shown in FIG. 2, and a generator according to a deviation between the frequency (actual frequency of the power system) detected by the frequency detector 26 and the rated frequency of the power system. A signal relating to the output correction value is output. The correction program includes a generator output correction value (M) corresponding to the deviation between the rated frequency of the power system, for example, 50 Hz, and the actual frequency of the power system (frequency detected by the frequency detector 26).
(W) is set (a negative generator output correction value is set when the frequency fluctuates in the positive direction from the dead band, and a positive generator output correction value is set when the frequency fluctuates in the negative direction beyond the dead band) Has been). The values α, β, and γ indicating the frequency fluctuation range are set as follows.

Α: Frequency fluctuation width for causing frequency control to take precedence over generator output control β: Boiler input amount (water, fuel, air) also changes with generator output fluctuation due to frequency control Frequency fluctuation width that needs to be performed γ: Frequency fluctuation width in which the boiler cannot follow up when frequency control is continued and becomes unstable The signal indicating the generator output target value and the generator output correction value are indicated to the adder 30 When signals are input, these signals are added and input to the upper / lower limiter 32. Here, the upper limit and the lower limit of the added signal are limited to arbitrary values, and then converted into a generator output request signal (MWD). That is, the generator output command generator 22, the change rate limiter 24,
The frequency detector 26, the function generator 28, the adder 30, and the upper / lower limiter 32 are configured as generator output request signal generating means.

The generator output request signal (MWD) is output to the boiler 10 as a target value of water, fuel and air, and is also output to a subtractor 36. A signal relating to the generator output detected by the generator output detector 34 is input to the subtractor 36, and the subtractor 36 outputs a signal corresponding to the deviation between the generator output request signal and the actual generator output. Output deviation ΔM
W is output. This deviation is input to the limiting circuit 38. The limiting circuit 38 receives the generator output command from the generator output command generator 22, the frequency signal detected by the frequency detector 26, and the generator output detected by the generator output detector 34. Is based on these input signals, when the frequency value is within the range of the set value (when the frequency fluctuation width is small), the output of the generator output deviation ΔMW or ΔMW ′ is allowed, and the frequency value is When the frequency fluctuates beyond the range of the set value, the output of the generator output deviation ΔMW or ΔMW ′ is limited.

Specifically, as shown in FIG. 3, the limiting circuit 38 includes signal generators 42 to 52 and an analog signal switch 5
4 to 60, a high signal selector 62, and a low signal selector 64. Each of the signal generators 42 and 48 is 0
% Of the generator output deviation, and a signal generator 4
4 outputs a signal indicating a generator output deviation of -X%, the signal generator 50 outputs a signal indicating a generator output deviation of X%, and the signal generator 46 outputs a signal indicating a generator output deviation of -100%. The signal generator 52 outputs a signal indicating a 100% generator output deviation. An analog signal switch 54 selects one of the signal generators 42 and 44, and an analog signal switch 56 selects a signal from the analog signal switch 54 or the signal generator 46, and a high signal selector. Reference numeral 42 selects and outputs a signal having a high level from the signal from the analog signal switch 56 or the generator output deviation ΔMW. An analog signal switch 58 selects a signal from the signal generator 48 or 50, and an analog signal switch 60 selects a signal from the analog signal switch 58 or a signal from the signal generator 52, and a low signal selector. Numeral 64 selects and outputs a low-level signal from the signal from the high signal selector 62 and the signal from the analog signal switch 60. Each of the analog signal switches 54 to 60 and the high signal selector 6
2. The selection conditions by the low signal selector 64 are set as follows.

High signal selector 6 for selecting a high level signal
In (2), unless the frequency is below -β shown in FIG. 2 and the generator output is increasing (when the value of the generator output command indicates a value forcibly increasing the output of the generator) When the signal from the signal generator 42 is selected and the generator output deviation ΔMW is 0% or less, the generator output deviation is fixed to 0%.

(2) When the frequency is between -α and β and the generator output is not increasing, the signal from the signal generator 44 is selected, and the generator output deviation ΔMW is less than -X%. Is selected as -X%.

(3) When the frequency is -α or higher or the generator output is increasing, the signal from the signal generator 46 is selected by the analog signal switch 56, but the high signal selector 62
Is selected, the generator output deviation is output to the proportional / integral calculator 40 without restriction.

A low signal selector 6 for selecting a low level signal
In (4), when the frequency is greater than or equal to β and the generator output is not falling, the signal from the signal generator 48 is selected;
When the generator output deviation ΔMW is 0% or more, it is fixed to 0%.

(2) The signal from the signal generator 50 is selected when the frequency is between α and β and the generator output is not falling, and when the generator output deviation ΔMW is X% or more, the generator is used. The output deviation is fixed at X%.

(3) When the frequency is lower than α or when the generator output is not decreasing, the signal from the signal generator 52 is selected by the analog signal switch 60. This signal is smaller than the generator output deviation ΔMW. Since it is at the high level, the generator output deviation ΔMW is selected by the low signal selector 62, and the generator output deviation ΔMW is output to the proportional / integral calculator 40 without any restriction.

As described above, in the limiting circuit 38, when the generator output is not increasing or decreasing, the generator output deviation is fixed to 0% when the frequency value is equal to or more than β or equal to or less than -β, and the turbine is adjusted. The valve operation command is limited to a generator output deviation of 0%, and at other times, that is, when the frequency value is between α and β or between −α and −β, the generator output deviation is set to −X%. And when the frequency value is between α and −α, the generator output deviation is output as it is.

Here, the reason why the generator output deviation is not limited with respect to the fluctuation of the generator output in the negative direction during the increase of the generator output is that it is necessary to return the frequency from the negative range to 0 Hz. To increase the output,
This is because limiting the output of the generator output deviation during the increase in the generator output has an adverse effect depending on the frequency control.

Further, the reason why the generator output deviation is not limited to the fluctuation of the generator output in the positive direction during the fall of the generator output is that it is necessary for the frequency to return from the plus region to 0Xz. This is because limiting the output of the generator output deviation while the generator output is falling has an adverse effect on the frequency control.

The generator output deviation output from the limiting circuit 38 is input to a proportional / integral calculator 40, which performs a proportional / integral calculation and outputs the result to the turbine controller 20 as a turbine control valve operation command.

On the other hand, the turbine control device 20 includes a rated frequency setting unit 66, a frequency detector 68, a subtractor 70, a function generator 72, and an adder 74. The rated frequency setting device 66 outputs a signal corresponding to the rated frequency of the power system to the subtractor 70. Subtractor 7
0 is the signal from the rated frequency setting unit 66 and the frequency detector 6
A signal corresponding to the deviation from the signal indicating the actual frequency due to the detection at 8 is output to the function generator 72.
A dead band corresponding to the frequency deviation is set in the function generator 72 so that the function generator 72 outputs a frequency signal for controlling the amount of steam in accordance with a signal from the subtractor 70. Has become. The adder 74 adds a signal from the function generator 72 and a turbine control valve operation command from the automatic plant control device 18 to output a steam amount control signal for operating the turbine control valve 12. .

In the above configuration, in the process of generating the generator output request signal and the turbine control valve operation command based on the generator output command, the frequency of the power system is monitored. A generator output request signal is generated according to the fluctuation, and a generator output deviation ΔMW is generated. Then, when compensating for the fluctuation of the frequency according to the generator output correction value, the output of the limiting circuit 38 is set when the frequency is β or more or −β or less, provided that the generator output is not increasing or decreasing. 0%
, And the turbine controller 20 constituting the turbine control system performs control for making the frequency of the system constant. That is, the signal from the function generator 72 is used prior to the turbine control valve operation command, and the constant frequency control is performed according to this signal. For this reason, it is possible to prevent the pullback phenomenon from occurring due to the turbine control valve operation command, and the frequency of the system can be quickly stabilized by controlling the turbine control system.

On the other hand, on condition that the generator output is not increasing or decreasing, when the frequency is between -α and β or between α and β, it is determined that the value of the frequency is within the set value range. The generator output deviation is fixed at -X% or X% or the output of the subtractor 36. Further, if the frequency is α and −
When it is between α, the output of the limiting circuit 38 is fixed to the output of the subtractor 36, assuming that the value of the frequency is within the set value range.

As described above, in this embodiment, provided that the generator output is not increasing or decreasing, when the frequency value exceeds β or −β and falls outside the range of the set value, Fix the output of circuit 38 to 0%,
According to the signal from the function generator 72, the turbine control valve 12
Is performed, it is possible to prevent a pull-back phenomenon from occurring due to a turbine control valve operation command at the time of a frequency change, and the frequency of the system can be quickly stabilized by controlling the turbine control system.

In the present embodiment, the dead zone most suitable for the boiler can be set in the correction program of the function generator 28 without being affected by the control of the turbine control device 20. Water as input,
Fuel and air can be controlled stably.

[0041]

As described above, according to the present invention,
When the frequency value of the power system frequency deviates from the set value range, the influence on the turbine control system by the turbine control valve operation command is limited, so that the pullback phenomenon caused by the turbine control valve operation command is prevented. This can contribute to frequency stabilization by control of the turbine control system.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a power plant control system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a correction program.

FIG. 3 is a block diagram of a limiting circuit.

FIG. 4 is an overall configuration diagram of a thermal power plant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Boiler 12 Turbine control valve 14 Turbine 16 Generator 18 Automatic plant control device 20 Turbine control device 22 Generator output command generator 24 Rate-of-change limiter 26 Frequency detector 28 Function generator 30 Adder 32 Upper / lower limiter 34 Power generation Machine output detector 36 Subtractor 38 Limiting circuit 40 Proportional / integral calculator 42-52 Signal generator 54-60 Analog signal switch 62 High signal selector 64 Low signal selector 66 Rated frequency setting device 68 Frequency detector 70 Subtraction Unit 72 Function generator 74 Adder

Continuing from the front page (72) Inventor Tomoki Fukuchi 3-2-1 Sachimachi, Hitachi-shi, Ibaraki Prefecture Within Hitachi Engineering Co., Ltd. (72) Inventor Toru 5-2-1 Omikamachi, Hitachi-shi, Ibaraki Hitachi, Ltd. In the Omika Factory (56) References JP-A-60-40730 (JP, A) JP-A-6-81606 (JP, A) JP-A-7-224610 (JP, A) JP-A-8-284616 (JP) JP-A-60-95104 (JP, A) JP-A-59-15609 (JP, A) JP-A-2-61302 (JP, A) JP-A-4-183904 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01D 17/24

Claims (7)

(57) [Claims] 1. A generator output request signal generating means for generating a generator output request signal for controlling an output of a boiler based on a generator output command for a generator connected to a power system, and a generator output request A turbine control valve operation command generating means for generating a turbine control valve operation command in accordance with a deviation between a generator output request signal generated by the signal generating means and an actual output of the generator; Means for controlling a steam control of a turbine based on a frequency signal corresponding to a deviation between a rated frequency of the power system and an actual frequency of the power system and a turbine control valve operation command, the turbine control system; Only when the actual frequency value is within the set value range, the output of the turbine control valve operation command is permitted, and the actual frequency value of the generator is out of the set value range. An automatic plant control device that limits the output of the turbine control valve operation command to the turbine control system when the frequency changes. 2. A boiler based on a generator output correction value set according to a deviation between a rated frequency of an electric power system and an actual frequency of the electric power system, and a generator output command for a generator connected to the electric power system. Generator output request signal generating means for generating a generator output request signal for controlling the output of
A turbine control valve operation command generating means for generating a turbine control valve operation command in accordance with a deviation between the generator output request signal generated by the generator output request signal generating means and the actual output of the generator; A valve operation command generating means is provided for a turbine control system that controls a steam amount to a turbine based on a frequency signal corresponding to a deviation between the rated frequency of the power system and the actual frequency of the power system and a turbine control valve operation command. Only when the actual frequency value of the generator is within the set value range, the output of the turbine control valve operation command is permitted, and the actual frequency value of the generator is out of the set value range. An automatic plant control device that limits the output of the turbine control valve operation command to the turbine control system when the frequency changes. 3. The turbine control valve operation command generating means, when the generator output command is a command for forcibly changing the generator output, outputs the turbine control valve operation command regardless of frequency fluctuation. The automatic plant control device according to claim 1 or 2, wherein 4. A generator output request signal for controlling an output of a boiler based on a generator output command for a generator connected to a power system, and a generator output request signal and an actual output of the generator. Automatic control plant that generates a turbine control valve operation command according to the deviation from the power plant, and a frequency signal generated according to the deviation between the rated frequency of the power system and the actual frequency of the power system and the plant automatic control device A turbine control device for generating a steam amount control signal for controlling the steam amount to the turbine based on the turbine control valve operation command, wherein the plant automatic control device has a value of an actual frequency of the generator. Output of the turbine control valve operation command is permitted only when is within a set value range, and a frequency fluctuation in which the actual frequency value of the generator is out of the set value range. A power plant control system that sometimes limits the output of the turbine control valve operation command. 5. A generator output request signal for controlling an output of a boiler based on a generator output command for a generator connected to a power system, and the generator output request signal and an actual generator output signal are generated. A turbine control valve operation command is generated in accordance with the deviation from the output, and steam to the turbine is generated based on a frequency signal corresponding to the difference between the rated frequency of the power system and the actual frequency of the power system and the turbine control valve operation command. For the turbine control system that controls the amount, the output of the turbine control valve operation command is permitted only when the actual frequency value of the generator is within a set value range, and the actual frequency of the generator is A frequency fluctuation compensation method in a power plant, which limits the output of the turbine control valve operation command to the turbine control system when the frequency of the power supply deviates from a set value range. 6. A boiler based on a generator output correction value set according to a deviation between a rated frequency of an electric power system and an actual frequency of the electric power system, and a generator output command for a generator connected to the electric power system. Generating a generator output request signal for controlling the output of the generator, generating a turbine control valve operation command according to the deviation between the generator output request signal and the actual output of the generator, the rated frequency of the power system The actual frequency value of the generator is set to a turbine control system that controls the amount of steam to the turbine based on a frequency signal corresponding to a deviation between the actual frequency of the power system and a turbine control valve operation command. The output of the turbine control valve operation command is allowed only when it is within the range of the value, and when the frequency value of the actual frequency of the generator is out of the set value range, the output to the turbine control system is changed. A frequency fluctuation compensation method in a power plant for limiting the output of the turbine control valve operation command. 7. The turbine control valve operation command according to claim 5 or 6, wherein when the generator output command is a command for forcibly changing the generator output, the output of the turbine control valve operation command is permitted regardless of a frequency change. Frequency fluctuation compensation method in power plant.