JP2960066B2 - Steam turbine controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a steam turbine control device for controlling the amount of steam flowing into a steam turbine by a steam valve.

(Prior Art) A steam valve is provided at an inlet of a steam turbine in order to obtain a steam turbine output corresponding to a power generation amount. The steam valve is opened and closed to flow a steam amount corresponding to the steam turbine output to the turbine. The opening and closing of the steam valve is controlled by a valve controller that determines the valve opening of the steam valve based on the relationship between the amount of power generation and the output of the steam turbine. The steam valve is opened by a command from this valve controller to increase the amount of steam. Alternatively, the output of the steam turbine is controlled by closing and conversely reducing the amount of steam.

As such a steam turbine control device, for example, the one shown in FIG. 3 is known.

In this figure, steam generated by a boiler 1 flows into a high-pressure turbine 4 through a main steam stop valve 2 and a steam control valve 3. The steam that has worked in the high-pressure turbine 4 merges with the steam that has passed through the high-pressure bypass valve 5, passes through the reheating section of the boiler 1, passes through the reheat stop valve 6, the intercept valve 7, and passes through the medium-pressure turbine 8.
Flows into The steam that has worked in the medium-pressure turbine 8 flows to the condenser after working in the low-pressure turbine 9 and flows into the boiler 1.
Circulating to A steam turbine output is obtained by the steam flowing into the high-pressure turbine 4, the intermediate-pressure turbine 8, and the low-pressure turbine 9, and the generator 10 is driven to obtain the output of the generator. On the other hand, the control of each of the valves 2, 3, 5, 6, 7 is performed as follows. The control command from the valve control device 11 is transmitted to the amplifiers 15a and 15a.
b, 15c, 15d, 15e, this amplifier 15a, 15b, 15c, 15d, 1
The signal amplified at 5e is sent to the oil cylinders 16a, 16b, 16c, 16d, 16e, and the main steam stop valve 2, the steam control valve 3, the reheat stop valve 6, the intercept valve 7, and the high pressure bypass, respectively. The valve 5 is opened and closed. Further, feedback signals 14a, 14b, 14c, 14d, 14e from the oil cylinders 16a, 16b, 16c, 16d, 16e are used as amplifiers 15a, 15b, 15c, 1
Adders 13a, 13b, 13c, 13d, 13 provided on the input side of 5d, 15e
Entered in e. The adders 13a, 13b, 13c, 13d, 13e subtract the feedback signals 14a, 14b, 14c, 14d, 14e from the oil cylinders from the output signals from the valve control device 11, and add the amplifiers 15a, 15
b, 15c, 15d, and 15e. In this way, each valve is controlled, the steam turbine is operated, and the output of the generator 10 is obtained by the total output of the high-pressure turbine 4, the intermediate-pressure turbine 8, and the low-pressure turbine 9.

By the way, during the opening and closing control of the steam valve, the steam valve is constantly moving, but when the steam turbine is not controlled, the steam turbine is in a stopped state.

For this reason, the sliding portion of the steam valve may stick (stick) due to oxidation scale or the like in the steam generated in the boiler. In order to avoid the stick of the steam valve, a valve test in which the sliding portion of the steam valve is moved by closing and opening the steam valve in any open state is performed. In this valve test, usually, the steam valve is slowly and fully closed from the current opening degree, and then slowly returned to the original opening state. This operation is performed by valve test biases indicated by reference numerals 17a, 17b, 17c, and 17d in FIG. The signals from the valve test biases 17a, 17b, 71c, 17d are sent to adders 13a, 13b, 13c, 13d. Here, the output signal of the valve control device is subtracted by the signal from the valve test biases 17a, 17b, 17c, 17d, becomes a signal for sliding the valve, and is sent to the amplifiers 15a, 15b, 15c, 15d.

(Problems to be solved by the invention) By the way, in the above-mentioned steam turbine control device,
When performing a valve test on a steam valve, when the valve is closed, the amount of steam flowing into the steam turbine is reduced, and the output of the turbine is reduced.

Therefore, even when the steam turbine output is operated at a constant level, the turbine output fluctuates up and down due to the execution of the valve test. As a result, the output of the generator also fluctuates, which is not preferable for the operation of the power plant.

For example, as shown in FIG.
22 is lowered at the start 23 of the valve test of the steam control valve 3 or the main steam stop valve 2. Also, the amount of steam flowing into the intermediate pressure turbine 8 and the low pressure turbine 9 downstream of the high pressure turbine 4 is slightly reduced, and the output 24 of the medium pressure / low pressure turbine is also slightly reduced. As a result, the total output 25 of the generator 10 will also decrease. Next, at the start of the valve test 26 of the reheat stop valve 6 and the intercept valve 7, the high-pressure turbine 4 is located upstream of both valves and is not affected. On the other hand, the intermediate-pressure turbine 8 and the low-pressure turbine 9 located downstream are affected, and their output 24 decreases, and the total output 25 of the generator 10 also decreases.

An object of the present invention is to solve the above problems and to provide a steam turbine control device capable of obtaining a stable turbine output even during a valve test.

[Configuration of the invention]

(Means for Solving the Problems) The present invention has been made to solve the above problems, and includes a boiler, a steam control valve, a high-pressure turbine, an intercept valve, and a low-pressure turbine in this order. A high-pressure turbine and a low-pressure turbine are connected by a generator and a shaft, and a flow path between the boiler and the steam control valve and a flow path between the high-pressure turbine and the intercept valve are connected by a high-pressure bypass valve. A steam control valve drive device provided in the steam control valve to drive the steam control valve; an intercept valve drive device provided in the intercept valve to drive the intercept valve; and a high pressure control device provided in the high pressure bypass valve. A high-pressure bypass valve driving device for driving a bypass valve, the steam control valve driving device, the intercept valve driving device, and the high-pressure bypass valve driving device; A valve control device for outputting a control signal to an actuator, a valve control bias for a steam control valve for outputting a valve test control signal to a control signal from the valve control device to the steam control valve drive device, and the valve control device A control signal from the valve control device to the intercept valve drive device, and a control signal from the valve control device to the steam control valve drive device. In the valve test of the intercept valve, a steam control valve output correction bias for outputting a correction bias for opening the steam control valve so as to increase the output of the high pressure turbine by an amount corresponding to the output reduction of the low pressure turbine, and In the control signal to the intercept valve drive device, during the valve test of the steam control valve, the low-pressure side The output correction bias for the intercept valve, which outputs a correction bias for controlling the intercept valve so as to increase the output of the turbine, and the control signal from the valve control device to the high-pressure bypass valve driving device, when the steam control valve is tested. And a high-pressure bypass valve output correction bias for outputting a correction bias for opening the high-pressure bypass valve.

(Operation) In the present invention, a control signal from the valve control device to the steam control valve drive device includes a control signal at the time of a valve test of the intercept valve.
The output correction bias for the steam control valve that outputs the correction bias that opens the steam control valve so that the output of the high pressure turbine is increased by the decrease in the output of the low pressure turbine, and the control signal from the valve control unit to the intercept valve drive unit During the valve test of the steam control valve, the output control bias for the intercept valve, which outputs a correction bias for controlling the intercept valve so as to increase the output of the low pressure turbine by an amount corresponding to the decrease in the output of the high pressure turbine, In the control signal to the bypass valve drive, during the valve test of the steam control valve,
The output correction bias for the high-pressure bypass valve that outputs the correction bias for opening the high-pressure bypass valve is provided. By controlling the intercept valve by the correction bypass, a decrease in the output of the high-pressure turbine can be compensated for by an increase in the output of the low-pressure turbine.

Further, at the time of the valve test of the intercept valve, the steam control valve output is output by outputting the steam control valve output correction bypass, and the decrease in the output of the low-pressure turbine can be compensated for by the increase in the output of the high-pressure turbine. Therefore, fluctuation of the total output of the turbine due to the valve test can be prevented, and stable operation can be performed.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS.
This will be described with reference to the drawings. The same components as in the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows a steam turbine control device according to the present invention. In this figure, reference numerals 18b, 18d, 18e indicate output correction biases, and the output correction biases 18b, 18d, 18e
Are input to adders 12b, 12d, and 12e.
Here, the output correction bias 18b,
The output signals of 18d and 18e are subtracted.

On the other hand, a reheat pressure detection device is
The high pressure turbine 4 is provided with a first stage shell pressure detecting device 20. A comparator 21 is connected to the output correction bias 18b of the steam control valve 3. The comparator 21 compares the detection value from the reheat pressure detection device 19 with the detection value from the first-stage shell pressure detection device 20 and, when the reheat pressure falls below a certain value, outputs the output correction bias 18.
b is activated.

Next, the operation of the control device will be described. Steam control valve 3
In the valve test, the adder 13b subtracts the valve test bias 17b and the feedback signal 14b from the output signal of the adder 12b, and outputs the difference to the amplifier 15b. This output is amplified by the amplifier 15b, sent to the oil cylinder 16b, and the steam control valve 3 is closed. On the other hand, the output correction bias 18e is subtracted from the output signal of the valve control device 11 by the adder 12e using the signal of the valve test bias 17b, and the feedback signal 14e is obtained from the difference.
Is subtracted by the adder 13e. The output of the adder 13e is amplified by the amplifier 15e, and the oil cylinder 16e is driven to open the high-pressure bypass valve 5. In addition, the signal of the valve control device 11 is added to the adder 12d, 13d, the amplifier 15d,
After 16d, the intercept valve 7 is closed. The steam flowing through the high-pressure bypass valve 5 passes through the reheat steam stop valve 6 and the intercept valve 7. At this time, the output correction bias 18d is subtracted from the output signal of the valve control device 11 by the adder 12d using the signal of the output correction bias 18d, and the adder 12d is added by the adder 13d.
The feedback signal 14d is subtracted from the output signal of. The deviation is amplified by the amplifier 15d to open the oil cylinder 16d. At this time, the output correction bias 18d of the intercept valve adjusts the output-equivalent steam amount required for the intermediate-pressure turbine 8 and the low-pressure turbine 9 by the intercept valve 7 in order to compensate for the decrease in the output of the high-pressure turbine 4 due to the steam control valve test. The bias is equivalent to the opening required for flowing. As described above, the decrease in the output of the high-pressure turbine 4 due to the valve test was caused to flow through the high-pressure bypass valve 5, and at the same time, the opening of the intercept valve 7 was moved from the fully open position to a controllable opening, and flowed through the high-pressure bypass valve 5. The amount of steam is controlled by the intercept valve 7. Then, the outputs of the medium- and low-pressure turbines 8, 9 can be increased so that the output of the generator 10 hardly fluctuates from the state before the valve test.

Next, a description will be given of a valve test of the reheat steam stop valve 6 and the intercept valve 7 performed in a chain. The adder 13c subtracts the feedback signal 14c and the valve test bias 17c from the signal of the valve control signal 11, and the deviation is amplified by the amplifier 15c. Then, the oil cylinder 16c is driven by the output signal amplified by the amplifier 15c, and the reheat steam stop valve 6 is closed. Next, in the adder 13d, the valve control device 11, the adder 1
The valve test bias 17d and the feedback signal 14d are subtracted from the signal that has passed through 2d, and the difference is amplified by the amplifier 15d. The oil cylinder 16d is driven by the output signal amplified by the amplifier 15d, the intercept valve 7 is closed, and a valve test is performed. At this time, the medium pressure turbine 8
The value detected by the reheat pressure detecting device 19 at the inlet of the high pressure turbine and the value detected by the first stage shell pressure detecting device 20 of the high-pressure turbine 4 are sent to the comparator 21 to reduce the reheat pressure 19 below a certain set value. When the output voltage drops, an output correction bias 18b is applied. The output of the high-pressure turbine 4 is increased by opening the steam control valve 3 from the current opening by the output correction bias 18b. This increase in output compensates for the decrease in output of the medium-pressure and low-pressure turbines 8, 9 and makes it possible to make the total output of the generator 10 hardly fluctuate before the valve test.

Next, the operation of this embodiment will be described with reference to FIG.

At the start 23 of the valve test of the main steam stop valve 2 or the steam control valve 3, the output 22 of the high pressure turbine 4 decreases. On the other hand, since the high-pressure bypass valve 5 is opened, the intercept valve 7 is opened.
The amount of steam flowing increases, and the output of the medium and low pressure turbines 8, 9 increases. Therefore, the total output 25 of the generator 10 hardly changes compared to before the valve test. Further, at the start 26 of the valve test of the reheat steam stop valve 6 and the intercept valve 7, the output 24 of the medium- and low-pressure turbines 8, 9 decreases. As a result, the reheat pressure decreases at the same time, but the first stage shell pressure does not change.
The step shell pressure difference becomes equal to or greater than the set value, and the output correction bias 18b is applied to the adder 12b. Output correction bias 18b
As a result, the signal of the adder 12b increases from before the valve test, the steam control valve 3 opens from the opening before the valve test, and the high-pressure turbine 4
Output 22 increases. As a result, medium- and low-pressure turbines 8,
The decrease in the output 24 of 9 is corrected, and the output 25 of the generator can be kept the same as before the valve test.

Thus, in the above embodiment, during the valve test of the steam control valve 3, the output correction bias of the high pressure bypass valve 5
By opening the high-pressure bypass valve 5 by 18e and controlling the intercept valve 7 by the output correction bypass 18d of the intercept valve 7, a decrease in the output of the high-pressure turbine 4 can be compensated for by an increase in the output of the middle and low-pressure turbines 8, 9. .

Also, at the time of the valve test of the reheat steam stop valve 6 and the intercept valve 7, the difference between the detection value of the first shell pressure detection device 20 and the detection value of the reheat pressure detection device 19 is determined by the comparator 21 and set. When the value becomes equal to or more than the value, the output correction bypass 18b is output to open the steam control valve 3, and the decrease in the output of the low / medium pressure turbines 8, 9 can be compensated for by the increase in the output of the high pressure turbine 4. Therefore, output fluctuation of the generator 10 due to the valve test can be prevented, and stable operation can be performed. For this reason, by simply adding the high-pressure bypass valve 5 and its circuit to the basic configuration of the steam turbine and using the steam control valve 3 and the intercept valve 7 that are already installed, a valve test can be performed. Can be very easily and easily prevented.

Further, since the high-pressure bypass valve 5 is operated, it is effective in warming the high-pressure bypass valve.

〔The invention's effect〕

As described above, in the present invention, the output reduction of the high-pressure turbine is compensated by increasing the output of the low-pressure turbine during the valve test of the steam control valve, and the output of the low-pressure turbine is reduced during the valve test of the intercept valve. Can be compensated by increasing the output of the high-pressure turbine. Therefore, it is possible to prevent fluctuations in the total output of the turbine, and to achieve an effect that stable operation can be performed. For this reason, by simply adding the high-pressure bypass valve and its circuit to the basic configuration of the steam turbine, and using the steam control valve and the intercept valve already installed, the turbine output during the valve test can be increased. Can be prevented very easily and easily.

[Brief description of the drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the operation and effect of the present invention, FIG. 3 is a diagram showing a conventional steam turbine control device, and FIG. 4 is a conventional steam turbine. FIG. 5 is a diagram illustrating output fluctuations in the control device. 1 boiler, 3 steam control valve, 4 high pressure turbine, 5 high pressure bypass valve, 7 intercept valve,
8 Medium pressure turbine 9 Low pressure turbine 11 Valve control device 17b 17d Valve test bias 18b 18d 18e
... Output correction bias.

Claims (1)

(57) [Claims] A boiler, a steam control valve, a high pressure side turbine, an intercept valve, and a low pressure side turbine are connected in this order; the high pressure side turbine, the low pressure side turbine, and a generator are connected by a shaft, and the boiler and the A steam control valve driving device that is connected to a flow passage between a steam control valve and a flow passage between the high-pressure turbine and the intercept valve by a high-pressure bypass valve and is provided in the steam control valve and drives the steam control valve An intercept valve driving device provided in the intercept valve to drive the intercept valve; a high pressure bypass valve driving device provided in the high pressure bypass valve to drive the high pressure bypass; the steam control valve driving device; and the intercept valve A driving device, a valve control device for outputting a control signal to the high-pressure bypass valve driving device, and the steam control device from the valve control device. A valve control bias for a steam control valve that outputs a valve test control signal as a control signal to a valve drive device, and an intercept valve that outputs a valve test control signal as a control signal from the valve control device to the intercept valve drive device And a control signal from the valve control device to the steam control valve driving device, the output of the high pressure turbine by the amount of the low pressure turbine output decrease during the valve test of the intercept valve. The output correction bias for the steam control valve that outputs the correction bias for opening the steam control valve so as to increase the pressure, and the control signal from the valve control device to the intercept valve driving device includes a high-pressure side during the valve test of the steam control valve. A correction via that controls the intercept valve to increase the output of the low-pressure turbine by the amount of the turbine output reduction The output correction bias for the intercept valve and the control signal from the valve control device to the high-pressure bypass valve driving device, for the high-pressure bypass valve that outputs the correction bias for opening the high-pressure bypass valve during the valve test of the steam control valve A steam turbine control device comprising an output correction bias.