JPS6218722B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an output control method and apparatus for a boiler-turbine power generation plant that performs variable voltage operation.

[Conventional technology]

FIG. 1 shows an outline of a conventional output control device for a once-through boiler operating at a constant pressure.

First, the output command signal (DPC signal) 1 from the intermediate supply
The output correction command signal (AFC signal) 2 from the intermediate feeder is limited by a rate of change limiter 3 and an AFC width limiter 4, and then added by an adder 5, and a frequency deviation signal 6 is added by an adder 7. Added.
This signal becomes an output request signal 10 via an output upper/lower limit setter 8 and a runback circuit 9.

The output request signal 10 and the generator output signal 11 are compared by a subtracter 12, and the output deviation signal 13 is inputted to a proportional-integral regulator 14 and becomes a main turbine adjustment valve opening command signal 15.

On the other hand, the output request signal 10 is added with the main steam pressure correction signal 17 by the adder 16 and becomes the boiler input request signal 18. The boiler input request signal is a request signal for the input amount of water, fuel, and air to the boiler.

The main steam pressure signal 19 and the main steam pressure set value 20 are compared in a subtracter 21, and the deviation signal 22 is applied to each proportional regulator 23 and integral regulator 24, and their output signals 25, 26 are summed. 27 and becomes the main steam pressure correction signal 17.

The signal switch 30 outputs the DPC signal 1, the output signal 29 of the manual output setting device 28, and the generator output signal 11.
This is to switch and select.

When the turbine control valve is manually operated in such a constant pressure operating plant, the signal switch 30 selects the generator output signal 11 and prohibits addition of the AFC signal and the frequency deviation signal. A mode in which such a generator output signal is used as an output command signal is called a load following mode.

If you manually open the turbine control valve at this point,
The output increases, while the pressure temporarily decreases,
The output signal 17 from the pressure correction circuit will eventually match the set value, so the main steam pressure will be as shown in Figure 2b.
Draw a trajectory of 101, and the opening degree of the adjusting valve is 102 on Figure 2 a.
The output stabilizes at 105.

On the other hand, when the regulating valve is manually closed, the output decreases and the pressure temporarily increases, but it eventually matches the set value due to the output signal 17 from the pressure correction circuit, so the pressure increases as shown in Figure 2b. A trajectory of 103 is drawn above, and the opening degree of the adjusting valve is a trajectory of 104 in Figure 2 a, and the output is stable at 106.

On the other hand, in variable pressure plants, the main steam pressure is set using a circuit as shown in Figure 3. 10 is a load request signal, and a function generator 300 generates a main steam pressure setting signal 31 according to the load request signal. 19 is a main steam pressure signal, 21 is a subtracter, 22
is the main steam pressure deviation signal.

Figure 4 shows an example of the main steam pressure setting value. This circuit performs constant pressure operation at low loads, e.g. 28% load or less, and at high loads, e.g. 90% load or more.
In the intermediate load zone, variable pressure operation is performed in which the generator output is varied by changing the main steam pressure setting. In this case, the opening degree of the turbine control valve is as shown in FIG. 5, and the opening degree is constant during variable pressure operation.

[Problem that the invention seeks to solve]

In a variable pressure operation plant using such a control method, the following problems occur when the turbine control valve is manually operated. However, when the turbine control valve is operated manually, it becomes load following mode.

For example, when a turbine control valve is manually closed, the output is reduced. The main steam pressure setting is programmed by the load request signal as shown in FIG. In this case, since it is the load following mode, the load request signal is generated by the generator output signal. Therefore, a decrease in output will decrease the output set value,
The main steam pressure will decrease. As a result, the output decreases beyond the effect of throttling the regulator valve, and the process of further decreasing the pressure set value is repeated.

Conversely, when the turbine control valve is manually opened, the output increases, and the increase in output causes the pressure set value to increase, resulting in a further increase in output, and the process is repeated.

As described above, when the turbine control valve is manually operated during variable pressure operation, a problem arises in that a positive feedback is established between the output and the pressure setting value, making it impossible to stably increase or decrease the generator output.

A first object of the present invention is to provide a generator output control method and device that can stably increase or decrease the generator output by manually operating a turbine regulating valve in a variable pressure operating plant. .
A second object of the present invention is to provide a method for controlling the output of a variable voltage boiler in which re-input from manual to automatic can be performed bumplessly.

[Means for solving problems]

The first feature of the present invention is that when the turbine control valve is manually operated during variable pressure operation, the main steam pressure setting value is held at the current setting value, and a transition is made to constant pressure operation using that pressure. The second feature of the present invention is that when returning the turbine regulator to automatic after manual operation, the boiler is controlled while gradually shifting to the main steam pressure set value during variable pressure operation that is commensurate with the manually changed output. It is characterized by

[Effect]

According to the present invention, the main steam pressure, which is maintained at the value immediately before switching to manual operation, does not follow fluctuations in the output, and there is a positive feedback between the output and the main steam pressure set value. Not satisfied. Therefore, it is possible to stably increase or decrease the generator output by manually operating the turbine control valve. Also, when returning from manual to automatic, the main steam pressure setting value will gradually shift. For this reason, it is possible to continue variable pressure operation by automatically reinserting the turbine control valve in a bumpless manner based on a manually changed load.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 6 is an example of a circuit for implementing the present invention.

1 in Figure 6 is a DPC signal and signal switcher 30-1
The signal is limited by the change rate limiter 3, and further passes through the signal switch 205, and the signal switch 207 at the adder 5.
It is added to the AFC signal 2 that has passed through the AFC width limiter 4. This signal is added to the frequency deviation signal 6 which has passed through the signal switcher 210 in the adder 7, and is then added to the output upper/lower limit limiter 8 and the runback circuit 9.
becomes the load request signal 10.

On the other hand, 28 is a manual output setting device, and the output from this device passes through the signal switch 30-2 and is stored in the analog memory 218. As the load request signal 10, the DPC signal 1 and the output signal of the manual output setter 28 are selected by the operator's switching operation, and the AFC signal 2 is selected.
The selection of exclusion from use is also made.

The load request signal 10 and the generator output signal 11 are compared in a subtracter 12, the control gain during voltage transformation and constant pressure operation is corrected in a gain correction circuit 303, and further passed through a signal limiter 304 and inputted into a proportional-integral regulator 14. This becomes a turbine control valve opening command signal 15 and is input to the turbine control valve drive device 307 .

On the other hand, the load request signal 10 is added with a main steam pressure correction signal 17 by an adder 16 and becomes a boiler input command signal 18.

The function generator 300 receives the load request signal 10 and programs the main steam pressure set value. 3
15 is a signal switch, and 316 is an analog memory, which together form a main steam pressure holding circuit. 317 is a rate of change limiter, and its output signal becomes the main steam pressure set value signal 20. This signal is compared with the main steam pressure signal 19 in a subtracter 21, its output is input to a proportional regulator 23 and an integral regulator 24, and the respective outputs are added together in an adder 27 to form the main steam pressure correction signal 17. An example of the main steam pressure setting program set by the function generator 300 is as shown in FIG. 4 described above.

With such an output control device, as shown in Figure 5, the opening of the turbine control valve changes depending on the output during constant pressure operation at low and high loads, and the opening remains constant during variable pressure operation in the intermediate load range. be driven.

Here, the operation when the turbine control valve is set to manual operation will be explained. In this case, the signal switch 20 in FIG.
5 selects the generator output 11, and at the same time, the signal switchers 207 and 210 respectively exclude the AFC signal 2 and the frequency deviation signal 6, and the load request signal 10 becomes a load following mode that follows the generator output 11. The signal switch 30-2 inputs the generator output signal 11,
The analog memory 218 stores the generator output signal.

Signal switch 315 selects the output of analog memory 316. Since the stored content of 316 is the immediately previous main steam pressure setting value, the main steam pressure setting value will be held as is.

When the turbine control valve is manually closed, the control valve opening moves from point 401 to point 402 in Figure 7a, drawing a locus 403, and the pressure is maintained at 404, so from point 405 to point 402. 406 to 407
It moves along a trajectory of , and the output becomes 408 and stabilizes.

From this state, to automatically turn on the turbine regulator and perform variable pressure operation, adjust the turbine regulator opening as shown in Figure 7a.
At point 409, the main steam pressure is at point 410 in Figure 7b.
need to be moved to.

When the turbine control valve is automatically turned on, the load following mode is canceled, and the load request signal 10 is retained in the stored contents of the analog memory 218, that is, the generator output signal 408 determined by manual operation of the turbine control valve. Also, since the signal switch 315 selects the output of the function generator 300 from the output of the analog memory 316, the input of the rate of change limiter 317 is from 404, and the main steam pressure set value 411 corresponding to the load 408 at that time is selected. The main steam pressure setpoint signal 20 changes to the main steam pressure setpoint 411 at the rate of change determined by the rate of change limiter 317.
will approach and eventually match. Since the main steam pressure set value decreases in this way, the main steam pressure also decreases to match the set value due to the operation of the main steam pressure correction circuit. Due to this decrease in main steam pressure, the generator output signal 11 also decreases.

On the other hand, the load request signal 10 is generated by the circuit described above.
Since it is held at 408, a generator output deviation signal is generated, and the turbine control valve is opened by automatic control to make the generator output equal to 408.

To explain these movements using Figures 7a and 7b, the main steam pressure changes from point 406 to point 410 in Figure 7b.
The turbine control valve opening degree moves from point 402 to point 409 in FIG. 7a on trajectory 413.
Draw and move. When the above operations are completed, the turbine regulating valve opening degree and main steam pressure return to the normal positions during variable pressure operation, so normal variable pressure operation becomes possible.

In FIG. 6, 308 is a rate of change limiter that removes harmonic components of the load request signal 10.
This becomes a program creation signal 309 based on the load. Further, 324 is a function generator in which a turbine control valve opening setting value is programmed. Reference numeral 325 is a turbine control valve opening signal, and the signal comparator 326 detects that the turbine control valve opening matches the set value, and indicates that the manually operated control valve position and main steam pressure are at the normal position during variable pressure operation. is determined to have been reached.

Based on this determination, an interlock is set up and while the deviation between the turbine regulator valve opening and the set value is greater than a certain value, the output setting can be manually increased or decreased.
Selection of DPC mode and reception of AFC signals are prohibited, and if the deviation becomes smaller than a certain value, it is determined that normal voltage transformation operation is possible, and the above control is canceled.

Conversely, even when the turbine regulator valve is manually opened, the main steam pressure set value is maintained at the current value, as in the case of a closed operation, so the turbine regulator valve moves along the trajectory 503 from point 501 to 502 in Figure 8a. , and the main steam pressure is 50 from point 505 to point 506 in Figure 8b.
It transitions while drawing a trajectory of 7, and the generator output is 50
Stable at 8. From this state, the method and circuit for automatically turning on the turbine regulator and performing normal variable pressure operation are the same as in the case of the closed operation, and the turbine regulator draws a trajectory 513 from point 502 to point 509 in Figure 8a, The main steam pressure is from point 506 to point 5 in Figure 8b.
It moves to 10 while drawing a trajectory of 512, and when this movement is completed, normal voltage changing operation becomes possible.

〔Effect of the invention〕

As described above, according to the method and apparatus for controlling the output of a boiler/turbine power generation plant in variable pressure operation according to the present invention, it is possible to stably increase or decrease the generator output even during variable pressure operation when the turbine regulator valve is manually opened and closed. Furthermore, even if the automatic switch is turned on again after a manual opening/closing operation, it is possible to return to normal variable voltage operation without bumping.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the output control circuit of a conventional constant-pressure once-through power generation plant, and Figure 2 shows changes in the regulator valve opening and main steam pressure when the turbine regulator valve is manually operated using the control circuit in Figure 1. Figure 3 is a block diagram of the main steam pressure setting circuit in a variable pressure operation plant, Figure 4 is a diagram showing an example of main steam pressure setting in a variable pressure operation plant, and Figure 5 is an adjustment to the pressure setting in Figure 4. 6 is a block diagram showing an embodiment of the present invention, and FIGS. 7 and 8 are characteristic diagrams illustrating the operation of the present invention. 1...Output command signal, 10...Load request signal,
218, 316... Analog memory, 15... Turbine regulating valve opening command signal, 15... Turbine regulating valve opening command signal, 300... Function generator, 31
7... Rate of change limiter, 20... Main steam pressure set value signal.

Claims (1)

[Claims] 1. Any one of a load command signal from an intermediate supply, a signal corresponding to a generator output, and a manual operation signal.
The opening of the turbine control valve at the turbine inlet is controlled by the output request signal obtained from two signals, and the main steam is obtained from the deviation between the main steam pressure set value and the actual main steam pressure, which changes depending on the load size. In an output control method for a variable pressure boiler/turbine power generation plant, in which the amount of fuel, water supply, and air on the boiler side is controlled using a signal obtained by adding a pressure correction signal to the output request signal, the output request signal is manually input. 1. A method for controlling the output of a variable pressure boiler/turbine power plant, characterized in that when operating a variable pressure boiler/turbine power plant, the main steam pressure set value immediately before the operation is maintained based on an operation signal, and the main steam pressure is controlled to this set value. 2 Any one of the load command signal from the intermediate supply, etc., the signal corresponding to the generator output, and the manual operation signal
The opening of the turbine control valve at the turbine inlet is controlled by the output request signal obtained from two signals, and the main steam is obtained from the deviation between the main steam pressure set value and the actual main steam pressure, which changes depending on the load size. In an output control method for a variable pressure boiler/turbine power generation plant, in which the amount of fuel, water supply, and air on the boiler side is controlled using a signal obtained by adding a pressure correction signal to the output request signal, the output request signal is manually input. When switching from the operating state obtained from the operation signal to another operating state, the main steam pressure setting value determined by the final main steam pressure setting value during manual operation and the load size in the other operating state is determined. An output control method for a variable pressure boiler/turbine power generation plant characterized by providing a setting value that changes gradually. 3 Output request signal setting means for determining an output request signal from any one of a load command signal from an intermediate supply, etc., a signal corresponding to the generator output, and a manual operation signal; a turbine control valve opening signal setting means for setting the opening degree of a turbine control valve at the turbine inlet based on an output request signal, and a deviation between the main steam pressure setting value and the actual steam pressure that changes depending on the magnitude of the load. and main steam pressure correction means for determining a main steam pressure correction signal from the input signal and adding this correction signal to the output request signal to generate a boiler input command signal, and adjusting the boiler fuel based on the boiler input command signal. In the output control device for a variable pressure boiler/turbine power generation plant configured to control the amount of water, the amount of water supply, and the amount of air, the main steam pressure modifying means further stores a main steam pressure set value that stores the main steam pressure set value. When performing an operation in which an output request signal is obtained from a manual operation signal, the main steam pressure set value immediately before the main steam pressure set value is stored and held in the main steam pressure set value memory means, and this held value is used as the main steam pressure set value. 1. An output control device for a variable pressure boiler/turbine power generation plant, characterized in that the output control device is configured to set the main steam pressure as the main steam pressure setting value of the steam pressure correction means.