JPS637245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power generation plant operation control device, and more particularly to a power generation plant operation control device suitable for controlling the startup operation of a power generation plant that frequently starts and stops.

Conventional power plant operation control equipment of this type is
A steam generator that generates steam at a predetermined temperature and pressure according to the thermal energy supplied through a combustion device that controls the amount of fuel and its combustion, and the steam from this steam generator that is supplied via a turbine control valve. a turbine power generation device that generates power according to the amount of steam supplied; a turbine bypass valve that bypasses steam from the steam generation device to a condenser or the like of the turbine power generation device; and a turbine power generation device that generates power in the turbine power generation device. a control circuit that takes in a load command that commands a quantity, and controls at least the combustion device, the turbine control valve, and the turbine bypass valve based on the previous command and various process quantity signals from the respective devices, and starts the combustion device. The system is configured to control operation during normal operation and during normal operation.

The operation control at the time of startup of the power plant operation control device configured in this way is first performed by supplying an appropriate amount of fuel to the steam generator and combusting it to input thermal energy in order to shorten the startup time. ,
This simultaneously increases the pressure of the steam generated from the steam generator and the temperature of the main steam.
Next, regarding an imbalance in the amount of steam generated from the steam generator with respect to the load command, the turbine bypass valve is opened to bypass a predetermined flow rate to the condenser. Therefore, in the above case, the amount of thermal energy supplied to the steam generator, that is, the amount of fuel, and the state of the steam generator have no effect on the predetermined power generation schedule from the turbine generator. Since it was not controlled, there was an inconvenience that a large amount of fuel was lost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power plant operation control device that eliminates the drawbacks of the prior art described above and suppresses loss of fuel amount.

In order to achieve the above object, the present invention supplies a large amount of fuel to the steam generator at the initial stage of startup, and also provides a large amount of turbine bypass so that the pressure and temperature of the steam from the steam generator are maintained at a predetermined level. The fuel amount is controlled according to the turbine bypass flow rate when the turbine bypass flow rate reaches the specified value.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a system diagram showing a schematic configuration example of a power plant operation control device according to the present invention. The boiler 10 as a steam generator is connected to a turbine-driven water supply pump 12 via a stop valve 16 during normal operation, or from an electric motor-driven water supply pump 14 during startup.
Feed water 100 is supplied to the boiler 10 via a feed water flow control valve 18, and fuel from a fuel pump 20 is supplied to the boiler 10 under control of a fuel flow control valve 22, and the water supply is controlled by a fuel flow control valve 22. Air from the fan 24 is controlled and supplied by a control damper 26.

Here, the fuel pump 20, the fuel flow control valve 22, the air supply fan 24, and the control damper 26 correspond to the combustion device that controls the thermal energy supplied to the boiler 10 as a steam generating device. In addition, as a water supply device for controlling water supply, a water supply pump 12,
14 and water supply flow control valves 16 and 18 correspond to this. The boiler 10 converts the feed water 100 in the boiler drum 10A into steam 1 according to the combustion of the fuel.
02, and the superheater 10B generates main steam 102A, which is then connected to the main blocking valve 28 and the high-pressure turbine control valve 30.
The high-pressure turbine 32 is supplied through the high-pressure turbine 32. This high-pressure turbine 32 is configured to generate rotational work according to the steam 102B controlled by the high-pressure turbine control valve 30, and is configured to be able to transmit the rotational work to the generator 34.

The steam 104 from the high pressure turbine 32 is further guided to the reheater 10C of the boiler 10, and the steam 106 heated in the reheater 10C is passed through a reheat stop valve 36 and an intercept valve 38. It is designed to be supplied to the low and intermediate pressure turbine 40. This low-intermediate pressure turbine 40 is configured to perform rotational work according to the steam 106A controlled by the intercept valve 38, and is configured to be able to transmit this work to the generator 34. The high pressure turbine 32 and the low and intermediate pressure turbine 4
0 and the generator 34 is configured to be able to output an amount of power according to its rotational work. The low and intermediate pressure turbine 40 is configured to send its steam 106A to a condenser 42, and the condenser 41 is configured to return the steam 106A to the pumps 12 and 14 as condensate 108. The suction sides of the feed water pumps 12 and 14 are made common so that feed water 110 containing condensate 108 can be taken in, and their discharge sides are made common and connected to a confluence point, and are connected to the boiler 10 as feed water 100. supply is becoming available.

Further, the inlet side and exhaust side of the main blocking valve 28 on the main steam intake side of the high-pressure turbine 32 are connected by a pipe 48 including a high-pressure turbine bypass valve 46 to bypass the high-pressure turbine 32. In addition, a pipe 52 equipped with a low pressure turbine bypass valve 50 that bypasses the steam 106 added to the low and intermediate pressure turbine 40 connects the inlet side of the reheat stop valve 36 and the condenser 42 to 40. Further, reference numeral 56 denotes a pressure detector provided at a portion after the discharge side merging point of the water supply pumps 12 and 14. Also,
The water supply piping is provided with a flow rate detector 58 that detects the flow rate of the water supply 100, and the high-pressure side steam piping is further equipped with a flow rate detector 60, a temperature detector 62, and a temperature detector 62 that detect the flow rate, temperature, and pressure of the steam 102A. A pressure detector 64 is provided. In addition, generator 3
A detector 66 for detecting the amount of power generation is provided at the output of No. 4. Steam 106 is installed in the low pressure side steam piping.
A reheat steam pressure detector 68 is provided to detect the pressure of the reheat steam.

Further, the low pressure turbine bypass piping 52 is provided with a low pressure bypass flow rate detector 70 that detects the low pressure bypass flow rate. Note that the fuel supply pipe is equipped with a fuel flow rate detector 72 for detecting the fuel flow rate.
is provided.

The control circuit 74 that controls the power generation plant is
Load command 76 and various detectors 56, 58, 60,
It is configured to take in various process amount detection signals from 62, 64, 66, 68, 70, and 72, and control the fuel flow control valve 22, control damper 26, and feed water flow control valve 18 based on these. There is.

In the power generation plant configured as described above, the control circuit 74 controls the combustion of the boiler 10 based on the load command 76, that is, controls the input thermal energy, and also controls the feed water pumps 12 and 14. The turbine 32 is controlled by controlling the regulating valve 30.
The rotation of the generator 34 is controlled, and the amount of power generated by the generator 34 is controlled. At this time, the control circuit 74 controls the various detectors 56, 58, 60, 62, 6 based on the load command 76.
Based on the process amount detection signals from 4, 66, 68, 70, and 72, the combustion device, control valve, bypass valve, etc. are controlled.

Note that, as described above, the turbine bypass valves (the high-pressure turbine bypass valve 46 and the low-pressure turbine bypass valve 50) return boiler-generated steam to the condenser 42 by bypassing the turbine when the plant is started.
Further, the steam flowing into the turbines 32 and 40 is controlled by a turbine control valve 30 and an intercept valve 38.

Furthermore, the operation at the time of startup of the power generation plant will be explained with reference to FIG. 2. Figure 2 is a waveform diagram for explaining the operation of a power generation plant, showing the main steam temperature,
The operation until the main steam pressure reaches the rated value is called start-up operation, and is generally distinguished from normal operation by a different control method. Figure 2 shows the time t
The graph shows the relationship between load, pressure, and temperature, with time on the horizontal axis and main steam flow rate on the vertical axis. In Figure 2, T _S is the main steam temperature, T _M is the rated temperature, P _S is the main steam pressure, P _M is the rated pressure, and L _D is the load command.
Q _S is the main steam amount, Q _HT is the high pressure turbine steam flow rate,
Q _TB is the turbine bypass flow rate. During normal operation (after time t ₁ ), the turbine bypass flow rate is
0 (that is, the bypass valves 46 and 50 are fully closed), but during startup operation (before time t ₁ ), the turbine bypass flow rate Q _TB is equal to the boiler generated steam 102A (Q _S in the figure). Turbine inflow rate 10
It exists as a difference between 2B (Q _HT in the figure). In order to quickly bring the main steam pressure P _S , degree T _S to the rated values P _M and T _M , a turbine bypass flow rate Q _TB occurs as a result of supplying fuel independently of the turbine input (i.e. load command L _D ). There is.

FIG. 3 is a block diagram showing a specific example of the control circuit in FIG. 1. In FIG. 3, the same components as in FIG. 1 are given the same reference numerals and will be explained. In the figure, a load command 76 is input to a subtracter 80 with the symbol shown in the figure, is subtracted from the detection signal from the power generation amount detector 66 to obtain a deviation, and this deviation is supplied to a proportional-integral (P+I) controller 81. The turbine control valve 30 is controlled by P+I.
Similarly, the load command 76 is input to a function generator 82 that outputs a pressure signal in response to the load command (MWD), and the output 83 from this function generator 82 is relayed.
It can be supplied to terminal a of RT ₁ . Next, in the subtractor 84, the fuel flow control valve 22 subtracts the fuel quantity command 85 selected by the relay RT ₂ and the detection signal from the fuel flow rate detector 72 to obtain a deviation, and outputs this deviation to the P+I controller. 86 to perform P+I control of the fuel flow control valve 22.
When the relay RT ₂ is activated, the terminal c-b is connected so that the fuel amount command from the initial fuel program circuit 87 is supplied. this relay
Even during startup, when the turbine bypass valve is fully closed, _RT2 connects terminals a to c and uses the output signal from the adder 88 as the fuel amount command. This adder 88 is configured to add the detection signal from the main steam flow rate detector 60 and the output signal from the P+I controller 89. This P+I
The controller 89 controls the deviation from the subtracter 90 by P+I, and the subtracter 90 subtracts the detection signal from the main steam pressure detector 62 and the pressure command signal 91 from the relay RT ₁ . It is. During normal operation, the relay RT ₁ has terminals a and c connected to output the output signal 83 of the function generator 82 as a pressure command signal 91, and at startup, terminals b and c are connected to operate the boiler starting pressure setting circuit. The output signal from 92 is output as a pressure command signal. On the other hand, the pressure command signal 91 is supplied to an adder 93, and during normal operation, relay RT ₃
is closed, the bias signal from the bias circuit 94 is added and supplied to the subtracter 95, and when starting, the relay _RT3 is opened and the pressure command signal 91 is sent to the subtracter 95. It is configured to be supplied as is. This subtractor 9
5 takes the deviation between the signal from the adder 93 and the actual detected pressure signal from the main steam pressure detector 62, supplies this deviation to the P+I controller 96, and
The I controller 96 controls the opening and closing of the high pressure turbine bypass valve 46 based on the deviation.

In addition, since relay RT ₄ is open at startup, the low pressure turbine bypass valve 50 has a set value.
Adding STB to a subtracter 98 via an adder 97,
The deviation from the detected pressure signal from the reheat steam pressure detector 68 is taken, and this deviation is added to the P+I controller 99, which controls the pressure. Further, in the turbine bypass valve 50, since the relay _RT4 is closed during normal operation, the bias STV is added to the set value STB by the adder 97 and supplied to the subtracter 98.
Note that the initial fuel program circuit 87 receives a bypass flow rate detection signal from the low pressure turbine bypass flow rate detector 70.

The operation of the control circuit 74 configured as described above will be briefly described. In the figure, the turbine control valve 30
The load command signal (MWD) 76 of the generator output set by the operator is set, the actual output (MW) from the generator detector 66 is fed back, the deviation is taken by the subtractor 80, and this is calculated as P+I. Controller 8
1 plus P+I control. Fuel flow control valve 22
is switching between three control modes.

First of all, during start-up operation, relay RT ₂
is connected to the terminal b side, and the signal from the initial fuel program circuit 87 becomes the fuel command 85. During the period when the turbine bypass valve 46 is open, the main steam pressure from the steam pressure detector 62 and the steam temperature detector 64 are
The signal from the initial fuel program circuit 87 is output even if the temperature from the fuel tank reaches the rated value. During start-up operation, when the turbine bypass valves 46 and 50 are fully closed, the relay RT ₂ is switched to the a side, and the relay RT ₁ is connected to the b side. At this time, the fuel command 85 is such as to maintain the main steam pressure setting value 91 created by the boiler starting pressure setting circuit 92.

During normal operation, relay RT ₁ switches to the a side and becomes the main steam pressure set value determined by the generator output command (MWD) signal. At this time, relays RT ₃ and RT ₄
is closed and the bias from bias 94 and bias STV are added. FIG. 4 is a block diagram showing a specific example of the initial fuel circuit 87.
The figure is an explanatory diagram of the operation of FIG. 4. In FIG. 4, a target value setting circuit 400 supplies a predetermined target setting signal 401, that is, a fuel amount signal corresponding to a load amount % set as a target, to a late limit circuit 402. This late limit circuit 402 is connected to the rate of change setting circuit 4.
Based on the command 404 from 03, the rate of change α of the signal for increasing the value corresponding to the target setting signal is controlled, and an output signal 405 is output.
The operation of this circuit will be explained with reference to FIG. The horizontal axis in FIG. 5 indicates time t, and the vertical axis indicates fuel command. When a target value is set in the target value (for example, 100%) setting circuit 400, the output signal 405 changes up to the target value 401 at the set rate of change α.
FIG. 6 is a block diagram showing a specific example of the boiler starting pressure setting circuit 92, and FIG. 7 is a waveform diagram for explaining the operation of FIG.

A target value 601 is set, and the target value 601 is supplied to a late limit circuit 602, and the pressure is changed to the target pressure set value at a rate of change set by a rate of change signal 604 of a rate of change setting circuit 603. is added to the function generator 605 to obtain a waveform as shown in FIG. 7 as an output signal 606.

According to this circuit, a signal that changes to the target pressure setting value at the change rate set by the change rate setting circuit 603 can be obtained.

FIG. 8 is a circuit diagram showing a specific example of the configuration of the target setting circuit 400 in FIG. 4. In the figure,
A fuel amount 410 corresponding to 100% load is supplied to an adder 411. This adder 411 has
The output signal from multiplier 412 is adapted to be provided. The multiplier 412 is supplied with a fuel bias 413 at the time of startup, and is also supplied with a turbine bypass flow rate 414 from the turbine bypass flow rate detector 70 via a proportional device 415 in reverse order. There is. In short, circuit 400 in this figure is a circuit that changes the target value setting of the initial fuel program at the turbine bypass flow rate. The target value of the fuel command is the fuel amount 410 at 100% load plus the fuel bias 413 at startup, and if the turbine bypass flow rate 414 increases, the fuel bias 413 at startup is decreased. It is. Note that it is desirable to raise the main steam temperature T _S to the rated temperature T _M as quickly as possible. In this case, the adder 41 in FIG.
Insert a switch between 1 and the multiplier 412, and T _S
The switch is closed on the condition that the value reaches a predetermined value. Further, in this circuit 400, when the turbine bypass flow rate 414 cannot be measured, the same purpose can be achieved using a turbine bypass valve command signal (for example, the output signal of the P+I controller 96). Also, set the target value of the fuel command to 100
% fuel amount 410 and fuel bias at startup 413
However, even if one set value is used and the target value of the fuel command is decreased by increasing the turbine bypass flow rate, the same effect as the above circuit can be achieved.

FIG. 9 is a waveform diagram shown to explain the case where this embodiment is used and the case where it is not used.
Components having the same meaning as the waveforms shown in the figure are given the same reference numerals. FIG. 9 is a waveform diagram for a case in which the load L _D increases and moves in stages and this embodiment is not applied _. This embodiment is not applicable to cases where there is a flat portion. This figure is a waveform diagram when this embodiment is applied and control is performed on the condition that the main steam temperature T _S reaches the rated temperature T _M. Cases 1 and 2 shown in FIG. 9 are cases where the generation of the main steam flow rate due to the amount of fuel in the boiler and the generator output required by the system are not balanced.
In such a case, it can be understood that fuel is lost by the turbine bypass flow rate.
However, according to this embodiment, after the main steam temperature T _S shown in FIG. Since the bypass flow rate increases, the main steam flow rate decreases, and the operation can be controlled as in case 3 shown in FIG. 9, resulting in energy savings.

As described above, according to the present invention, the amount of fuel can be reduced as the turbine bypass flow rate increases during startup, so there is an effect that the amount of fuel can be reduced and energy can be saved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the power plant operation control device according to the present invention, and FIG. 2 is a waveform diagram shown to explain the operation of the power plant,
FIG. 3 is a block diagram showing a specific example of the control circuit of the power plant operation control device according to the present invention, FIG. 4 is a block diagram showing a specific example of the initial fuel program circuit used in the control circuit, and FIG. FIG. 4 is an explanatory diagram of the operation, and FIG. 6 is a block diagram showing a specific example of the boiler starting pressure setting circuit used in the control circuit.
7 is an explanatory diagram of the operation of FIG. 6, FIG. 8 is a block diagram showing a specific example of the fuel command target value setting circuit in the initial fuel program circuit of FIG. 4, and FIG.
and are waveform diagrams shown for explaining the operation of the embodiment of the present invention. 10...Steam generator (boiler), 12...Water pump, 16...Water flow control valve, 22...Fuel flow control valve, 28...Turbine control valve, 32...High pressure turbine, 34... Generator , 38... intercept valve, 40... low and intermediate pressure turbine, 42... condenser,
46... High pressure turbine bypass valve, 50... Low pressure turbine bypass valve, 70... Low pressure turbine bypass flow rate detector, 87... Initial fuel program circuit, 92... Boiler starting pressure setting circuit, 400...
...Target value setting circuit.

Claims (1)

[Claims] 1. Control the state variables of the power generation plant including the amount of power generation and fuel amount based on a predetermined start-up operation schedule, and control the turbine bypass flow rate to make the main steam pressure match the value based on the schedule. In this power plant operation control device, when a detection signal indicating that the main steam temperature has reached a predetermined value is input, the amount of fuel is decreased or A power generation plant operation control device characterized by being provided with a control circuit for incremental correction.