JP2001241607A - Method for load control on start-up of backup of feed- water pump backup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize an operational condition of a plant, and improve availabil ity factor of the plant, in the event of emergency shutdown of at least one pump in the operation of two or more turbine driven BFP(boiler feed water pump). SOLUTION: In the event of emergency shutdown of one pump during operation of two turbine driven BFP, it is judged whether a motor driven BFP is on standby or not (801), then it is judged whether generator output is at least 60% or not (802). Further it is determined whether one pump during operation of two turbine driven BFP is stopped or not (803), and in the event of shutdown of one pump, a motor driven BFP is automatically started up (804), and further an MWD signal (generator output command signal) is switched to a signal on a water feed signal base (805). Next recovery of water-supply quantity is recognized (806), and a backup start-up of the motor driven BFP is completed (807). Then a generator output command value is controlled in accordance with insufficient amount of feed water due to startup of the motor driven BFP in order to minimize a reduction in the generator output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling water supply of a thermal power plant and a method for controlling generator output, and more particularly, to a method for controlling a decrease in generator output in a thermal power plant having a plurality of boiler feed pumps (BFP). The present invention relates to a load control method at the time of starting a water supply pump backup to be minimized.

[0002]

2. Description of the Related Art Conventionally, a generator output control method for a thermal power plant has realized a deviation between a generator output command value and an actual output of the generator by opening and closing a turbine control valve. Also,
The water supply control method uses the generator output command value (hereinafter referred to as MWD).
Abbreviated as signal. ) To calculate the feedwater flow rate from the boiler's static characteristics, and adjust the opening and closing of the operating turbine BFP opening / closing valve using the deviation from the actual feedwater flow rate as the feedwater flow rate command to increase or decrease the rotation of the turbine BFP. Alternatively, the adjustment is performed by opening and closing the opening of the feedwater flow rate adjustment valve of the motor-driven BFP during operation. In a thermal power plant composed of a plurality of BFPs, a turbine-driven BFP2
If one of the units is stopped in an emergency during the operation of the unit,
As in the water supply control method at the time of load runback described in Japanese Patent Application Laid-Open No. 60608, the generator output is reduced to an output value that can be operated by one turbine drive BFP to stabilize the water supply.

[0003]

According to the prior art, when one of the turbine-driven BFPs is stopped in an emergency while the other two turbine-driven BFPs are operating, the MWD signal is reduced to a value that can be handled by the rated capacity of the continuously-operated turbine-driven BFP. There was a load run-back control method to be performed. Further, it was possible to start the motor drive BFP at the discretion of the operator after the load runback and adjust the generator output while confirming the stability of the water supply control. However, before starting the motor-driven BFP, preparations before starting, such as warming of the BFP, are required, and during this time the generator output is limited to 50%. There were challenges.

An object of the present invention is to solve the above-mentioned problems by stabilizing the operation state of a plant when one or more turbine-driven BFPs are emergency stopped during the operation of two or more turbine-driven BFPs.
Another object is to improve the operation rate of the plant.

[0005]

In order to solve the above-mentioned problems, in the case where one or more turbine-driven BFPs are emergency-stopped while two or more turbine-driven BFPs are operating, the backup motor-driven BFP is automatically started to minimize the decrease in generator output. And Here, the generator output command value for minimizing the generator output decrease is suppressed in accordance with the water supply shortage caused by the activation of the backup motor drive BFP. Further, when the backup motor drive BFP outlet valve is fully opened and the water supply amount decrease phenomenon is eliminated, the generator output value is restored to the value before the emergency stop of one or more turbine drive BFPs. In addition, turbine drive BF
If one or more emergency stop occurs while driving two or more P,
The backup motor drive BFP is automatically started, and the generator output command value for minimizing the generator output decrease is suppressed in accordance with the water supply shortage caused by the start of the backup motor drive BFP, and the backup motor drive BFP outlet. When the valve is fully opened and the decrease in the amount of supplied water is stopped, the generator output value is restored to a value that can be secured by the operating turbine drive BFP and backup motor drive BFP.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration for realizing a load control method at the time of starting a water supply pump backup according to an embodiment of the present invention. The thermal power plant has boiler 2, turbine 3,
It is composed of a generator 4 and auxiliary equipment for assisting them.
In the boiler 2, high-temperature, high-pressure steam is generated by thermal energy generated by burning fuel supplied to the boiler 3, and the amount of steam sent to the turbine 3 is adjusted by adjusting the opening of the turbine control valve 12. adjust. In the turbine 3, high-temperature, high-pressure steam is converted into kinetic energy, and the kinetic energy is converted into electric energy by a generator 4 connected to the turbine 3, and electricity is sent out of the thermal power plant. Part of the steam that worked in the turbine 3
Then, the cooling water such as seawater is reused for boiler feed water, and a part is used as steam for driving the turbines BFP5 and BFP7. That is, the turbine drive A-BFP 6
Adjusts the amount of steam to the A-BFP turbine 5 by the A-BFP turbine driving steam control valve 13 and
The number of rotations of the turbine 5 is controlled, and a turbine drive A-BFP
Adjust the feedwater flow of 6. Similarly, turbine drive BB
The FP 8 adjusts the amount of steam to the B-BFP turbine 7 by the steam control valve 14 for driving the B-BFP turbine, and
The rotation speed of the BFP turbine 7 is controlled, and the turbine drive B-
Adjust the feedwater flow rate of BFP8. In addition, the C-BFP electric motor 9 starts the motor drive C-BFP 10 to reach the rated rotation speed after a certain start-up time.
The BFP feed water flow control valve 15 is controlled, and the motor drive C-BFP
Adjust the water supply flow rate of 10. The water from the condenser 11 is boosted by the turbine drive A-BFP 6, the turbine drive B-BFP 8, and the motor drive C-BFP 10, and AB
FP outlet valve 16, B-BFP outlet valve 17, and C-BFP
Water is supplied to the boiler 2 via the feedwater flow regulating valve 15 and the C-BFP outlet valve 18.

The operation of the control circuit of the control device 1 will be described. A corrected MWD signal is generated from the generator output command signal (MWD) 100 and the water supply signal 19 by a corrected MWD signal generation circuit 101 described later in FIG. A deviation calculator 103 creates an MWD deviation signal from the generator output signal 23 and the corrected MWD signal, and an opening command for the turbine control valve 12 is created by a proportional integrator 104. Further, the corrected MWD signal is used to create a main steam pressure setting signal by the function generator 116, the main steam pressure detection value 24 and the deviation calculator 105 are used to create a main steam pressure deviation signal, and are calculated by the proportional integrator 106. , A boiler input command signal (hereinafter, B
Abbreviated as ID signal. ) To create. Based on the BID signal, a set value of the water supply flow rate is created by the function generator 107, a water supply flow rate deviation signal is calculated by the water supply flow rate detection value 19 and the deviation calculator 108, and B is calculated by the proportional integrator 109.
Create a water supply command signal to the FP. Water supply command signal and A-
Deviation calculator 1 from signal of BFP suction flow rate detector 20
The A-BFP water supply deviation is calculated by 10 and the proportional integrator 111 adjusts the A-BFP turbine drive steam control valve 13 to control the A-BFP water supply flow rate. Similarly,
The deviation calculator 112 calculates the water supply deviation of the B-BFP from the water supply command signal and the signal of the B-BFP suction flow rate detector 21, and adjusts the B-BFP turbine drive steam control valve 14 by the proportional integrator 113 to obtain the B-BFP. -Control the feed water flow rate of the BFP. Similarly, a deviation calculator 114 calculates a C-BFP from the water supply command signal and the signal of the C-BFP suction flow rate detector 22.
The water supply deviation of the BFP is calculated, and the proportional integrator 115 calculates C-B
The FP feedwater flow control valve 15 is adjusted to control the feedwater flow rate of the C-BFP.

FIG. 2 shows a corrected MWD signal generation circuit 101.
The details will be described. The feedwater flow signal 19 is supplied to a hold command 102 in a pre-switch value hold computing unit 1010.
2. Hold the signal. The deviation calculator 1011 includes a feedwater flow signal 19 and a pre-switching value hold calculator 1010.
Is calculated, and the function generator 1012 creates an MWD signal correction signal based on the feedwater flow rate deviation signal. The signal switch 1013 includes a MWD signal correction signal, an output signal of the signal generator 1016, and a feedwater deviation input signal 102.
When the condition 6 is satisfied, the MWD signal correction signal is selected. The signal change rate limiter 1014 enables the correction change rate of the MWD signal correction signal to be adjusted according to the response characteristics of the thermal power plant. On the other hand, the MWD signal 100 is supplied to the hold command 1022
Holds, the signal is held. Signal adder 101
5 generates a corrected MWD signal by adding the MWD signal correction signal and the MWD hold signal.

Next, the conditions for establishing the hold command 1022 will be described. If the C-BFP backup activation command 310 is satisfied, the hold command 1022 is satisfied, and the logical sum calculator 1019 holds the hold command 1022. The reset signal of the hold command 1022 is output from the signal deviation detector 10.
At 18, the input value and the output value of the pre-switching value hold computing unit 1017 are compared, a MWD signal restoration signal is detected with the same value, and this signal is computed by the signal inverter 1020, and input to the logical product computing unit 1021. Then, the hold command 1022 is reset. The conditions for establishing the feedwater deviation input signal 1026 will be described. If the motor drive C-BFP backup start command 310 is satisfied, the water supply deviation input 1026 is satisfied,
The OR operation unit 1023 holds the feedwater deviation input 1026. The reset signal of water supply deviation input 1026 is C-BFP
The outlet valve fully open signal 400 is calculated by the signal inverter 1024,
The data is input to the logical product calculator 1025, and the water supply deviation input 1026 is reset.

Referring to FIG. 3, conditions for establishing a motor-driven C-BFP backup start command will be described. Of the conditions of A-BFP operation 300 and B-BFP operation 301 which are the turbine drive BFP, A-BFP operation 300 and B
A signal obtained by calculating the signal 301 during the BFP operation by the signal inverter 304 is input to the AND operator 306, and conditions for operating one A-BFP are created. Similarly, during B-BFP operation 301
Then, a signal calculated by the signal inverter 305 during the A-BFP operation 300 is input to the logical product calculator 307, and conditions for operating one B-BFP are created. The output signal of the logical product calculator 306 and the output signal 308 of the logical product calculator 307 are input to the logical sum calculator 308 to generate a signal for operating one turbine drive BFP. Next, the condition of the C-BFP standby state 302 and the condition 303 of the generator output of 60% or more are calculated by the logical product calculator 309 with the operation signal of one turbine drive BFP which is the output signal of the logical sum calculator 308. , C-BFP
A backup start command 310 is created.

In FIG. 4, the C-BFP feed water shutoff valve is fully opened by a C-BFP backup start command 310, and the C-BFP feed water flow control valve 15 is also fully opened once. Command signal 403
Create In addition, C-BFP water stop valve fully open signal 400
Is calculated by a signal inverter 401 and is calculated by a logical product calculator 402 to reset the C-BFP feedwater flow control valve fully open command signal 403 and to output the C-BFP feedwater flow control valve fully open signal 40.
3 is set as an automatic return command of the C-BFP feedwater flow control valve 15 by the signal inverter 404.

FIG. 5 shows another corrected MWD signal generating circuit 101 according to the present invention. Only differences from FIG. 2 will be described. FIG. 5 is characterized in that a limiting circuit is added for a plant in which the capacity of the motor driving BFP is smaller than the capacity of the turbine driving BFP. Signal generator 1027
Is set to a value obtained by adding the capacity of one turbine drive BFP and the capacity of the motor drive BFP to be backed up.
For the signal generator 1028, the maximum power output (normally 100%) of the thermal power plant is set. Signal switch 1029
Is switched to the signal generator 1027 when the selection condition of the MWD upper limit 1032 is satisfied. Next, as the signal upper limit value 1030, a smaller value of the hold signal of the pre-switching value hold calculator 1017 and the signal of the signal switcher 1029 is selected. Further, the signal change rate limiter 1031 can adjust the correction change rate of the MWD signal correction signal in accordance with the response characteristics of the thermal power plant. Further, the signal detector 10
18 compares the MWD signal with the output value of the rate-of-change limiter 1031 and determines whether the MWD signal 100 is the value before switching or the motor drive B for backing up the capacity of one turbine drive BFP.
When the value obtained by adding the capacity of the FP becomes
The D signal restoration condition is satisfied. Furthermore, the MWD upper limit 1
The selection condition of 033 is that the C-BFP backup start command 310 and the C-BF are selected so that the water supply flow rate does not drop and the motor drive BFP backs up.
The P outlet valve fully open signal 400 is a signal calculated by the logical product calculator 1032.

FIG. 6 shows the process behavior at the time of starting the water supply pump backup. The horizontal axis represents time (seconds), the vertical axis represents feedwater flow rate (T / H) and MWD signal (%).
-BFP water supply flow rate, 602 is A-BFP water supply flow rate, 60
Reference numeral 3 denotes a C-BFP feedwater flow rate, 604 denotes a feedwater flow rate, and 605 denotes an MWD command signal. B-BF of turbine driven BFP
The emergency stop (B-BFP trip) of P causes B-
BFP feedwater flow rate 601 can be changed from 500T / H to 0T /
H. C-BFP at the same time as B-BFP trip
Automatically starts, but the C-BFP feedwater flow rate 603 is
Due to the fully open time of the FP water supply stop valve 18 and the activation time of the C-BFP drive motor 9, the rated water supply flow rate is reached after 30 seconds. During this time, the A-BFP temporarily increases the feedwater flow rate up to the maximum flow rate of 600 T / H, and further increases the MWD signal 60
By reducing 5 in proportion to the decrease in the feedwater flow rate 604, the plant can be operated with a minimum decrease in generator output while ensuring the balance of the entire plant.

FIG. 7 shows a process behavior at the time of starting the water supply pump backup when the capacity of the motor drive BFP is smaller than that of the turbine drive BFP and the maximum load of the generator cannot be ensured even when the motor drive BFP is started. The horizontal axis represents time (seconds), the vertical axis represents feedwater flow rate (T / H) and MWD signal (%), 601 is B-BFP feedwater flow, 602 is A-BFP feedwater flow, 603 is C-BFP feedwater flow. ,
Reference numeral 605 denotes an MWD command signal. The emergency stop (B-BFP trip) of the B-BFP of the turbine drive BFP causes the B-BFP feedwater flow rate 601 to decrease from 500 T / H to 0 T / H in 2 seconds. C at the same time as B-BFP trip
-BFP starts automatically, but C-BFP water supply flow rate 603
Reaches the rated water supply flow rate after 25 seconds due to the fully open time of the C-BFP water supply stop valve 18 and the activation time of the C-BFP drive motor 9. However, the rated capacity of B-BFP is 500T /
H cannot be secured. During this time, the A-BFP water supply flow rate 6
02 temporarily increases to the maximum flow rate of 600 T / H,
Further, by reducing the MWD signal 605 in accordance with the decrease in the feedwater flow rate 604, the plant can be operated with a minimum decrease in the generator output while ensuring the balance of the entire plant. Does not reach the maximum load of the generator,
04 is the sum of the A-BFP feedwater flow rate 602 and the C-BFP feedwater flow rate 603. Similarly, the MWD command value 605 is also up to a value corresponding to the restoration value of the water supply flow rate 604.

FIG. 8 shows a functional flow of the present invention. 80
At 0, it is determined at 801 whether the motor drive BFP is in a standby state. Next, at 802, the generator output is 60
% Is determined. Further, in 803, the turbine drive BFP
Check if one of the two units has stopped during operation. If one of the turbine-driven BFPs is stopped during operation, the motor-driven BFP is automatically started at 805. Further, at 805, the MWD signal is switched to a feedwater signal-based signal. Next, 806
Confirms that the water supply flow rate has been restored, determines that the motor-driven BFP butts-up activation has been completed in 807, and ends in 808.

[0016]

As described above, according to the present invention,
In the case of a thermal power plant composed of a plurality of BFPs, if one or more of the turbine-driven BFPs is stopped in an emergency while operating two turbine-driven BFPs, the backup motor-driven BFP is automatically started to minimize the generator output time limit. At the same time, the generator output command value (MWD) signal is suppressed in accordance with the reduction of the water supply flow rate due to the start-up time of the backup motor drive BFP, so that the balance between the boiler and the turbine / generator can be secured, and the plant operating condition can be secured. It can stabilize and improve the operation rate of the plant.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for realizing a load control method at the time of starting a water supply pump backup according to an embodiment of the present invention;

FIG. 2 is a detailed diagram of a corrected MWD signal generation circuit according to the present invention.

FIG. 3 is a diagram illustrating conditions for establishing a motor-driven C-BFP backup start command according to the present invention.

FIG. 4 is a diagram illustrating a motor-driven C-BFP outlet valve fully open command according to the present invention.

FIG. 5 is a detailed diagram of a corrected MWD signal generation circuit when the motor-driven C-BFP capacity is smaller than the turbine-driven BFP capacity according to the present invention.

FIG. 6 is a behavior diagram of a main process at the time of starting a water supply pump backup according to the present invention.

FIG. 7 is a behavior diagram of a main process at the time of starting the water supply pump backup when the motor-driven C-BFP capacity of the present invention is smaller than the turbine-driven BFP capacity.

FIG. 8 is a functional flow diagram of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Control device, 2 ... Boiler, 3 ... turbine, 4 ... Generator, 5 ... A-BFP turbine, 6, Turbine drive AB
FP, 7: B-BFP turbine, 8: Turbine drive B-
BFP, 9 ... C-BFP electric motor, 10 ... Motor drive C-BFP, 11 ... Water cover, 12 ... Turbine control valve,
13 ... A-BFP turbine drive steam control valve, 14 ... B
-BFP turbine drive steam control valve, 15 ... C-BFP
Water flow regulation

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshiyuki Ozeki 3-1-1, Sakaimachi, Hitachi-shi, Ibaraki F-term in the Thermal and Hydropower Division, Hitachi, Ltd. (Reference) 3H045 AA01 AA09 AA16 AA23 AA31 BA02 BA03 CA23 CA30 DA01 EA02 EA12 EA38 3L021 AA05 CA01 DA38 EA04 FA28

Claims (4)

[Claims] 1. A boiler feed pump (hereinafter referred to as BF)
Abbreviated as P. ), The maximum output of the generator is secured by two or more turbine-driven BFPs during normal operation, and in a thermal power plant including one or more motor-driven BFPs for backup, a turbine-driven BFP2 is used.
A load control method at the time of starting a water supply pump backup, characterized in that when one or more units are emergency stopped during operation of more than one unit, a backup motor drive BFP is automatically started to minimize a decrease in generator output. 2. The turbine drive BFP according to claim 1,
When one or more units are stopped in an emergency during the operation of two or more units, the backup motor drive BFP is automatically started, and the generator output command value for minimizing the generator output decrease is started. A load control method at the time of starting a water supply pump backup characterized by suppressing the water supply shortage caused by the water supply pump. 3. The turbine drive BFP according to claim 1,
When one or more units are stopped in an emergency during the operation of two or more units, the backup motor drive BFP is automatically started, and the generator output command value for minimizing the generator output decrease is started. The water supply shortage caused by the
A load control method at the time of starting a water supply pump backup, wherein the FP outlet valve is fully opened to restore the generator output value before one or more turbine-driven BFPs have been emergency-stopped when the phenomenon of reduced water supply has disappeared. 4. The turbine drive BFP according to claim 1,
When one or more units are stopped in an emergency during the operation of two or more units, the backup motor drive BFP is automatically started, and the generator output command value for minimizing the generator output decrease is started. The water supply shortage caused by the
When the FP outlet valve is fully opened and the water supply amount decrease phenomenon is eliminated, the generator output value can be restored to a generator output value that can be secured by the operating turbine drive BFP and the backup motor drive BFP. Load control method.