JP2558869B2 - Turbine controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides an intercept valve and a bypass valve in a steam system, and the intercept valve is proportional to the flow rate of the main steam control valve during bypass operation. The present invention relates to a turbine control device that controls the speed of an intercept valve based on a turbine speed and a load setting signal when the bypass operation is completed.

(Prior Art) Generally, in a steam power generation system, high-temperature and high-pressure steam generated by a boiler is sent to a turbine to rotate the turbine, and the rotating torque drives a generator to generate electric power. Also, the steam that has finished the work of rotating the turbine is returned to the water in the condenser.

In such a steam power generation system, when the generator output is connected to the grid side and load operation is performed, if the generator breaker that connects the generator to the grid opens for some reason, the turbine operates at the rated Move to operation or stop.

Therefore, when such a situation occurs, the flow rate of steam supplied to the turbine changes abruptly, which makes it impossible to control the boiler stably, and the plant stops.

In this way, once the plant is stopped, it takes a long time to re-orbit the plant, and thus the time required to reconnect the generator output to the grid becomes long.

A turbine bypass operation method is one of the methods for shortening the time required to restart the plant after opening the generator circuit breaker during load operation.

FIG. 3 shows an example of a steam power generation system that performs a turbine bypass operation method.

A part of the steam generated from the superheater 1 of the boiler is supplied to the high-pressure turbine 3 via the steam control valve 2, and the other steam is directly supplied to the high-pressure turbine 3 via the high-pressure turbine bypass valve 4. You will be led to the exit.

The steam supplied to the high-pressure turbine 3 causes the high-pressure turbine 3 to rotate, and the steam that has finished its work and the steam that has flowed through the high-pressure turbine bypass valve 4 merge and are guided to the reheater 5 in the boiler. After the temperature is raised, a part thereof is sequentially supplied to the intermediate pressure turbine 7 and the low pressure turbine 8 through the intercept valve 6, and the intermediate pressure turbine 7 and the low pressure turbine 8 are rotationally driven, respectively, and then the condensate is condensed. Guided by vessel 9 to return to water.

Further, of the steam flowing out from the reheater 5, the part that does not flow into the intercept valve 6 is the low pressure turbine bypass valve 10
Directly flows into the condenser 8 via.

In this way, the high pressure turbine 3, the intermediate pressure turbine 7,
And the low-pressure turbine 8 rotates, which drives the generator 11 to obtain the generator output.

Now, in this turbine bypass operation method, the steam generation flow rate of the boiler is controlled so as not to become smaller than the minimum flow rate at which the boiler can be stably operated.
When the flow rate of steam required for driving the engine is smaller than the minimum flow rate, steam corresponding to the difference in flow rate is supplied to the high-pressure turbine bypass valve 4 and the low-pressure turbine bypass valve 10
It directly flows into the condenser 9 via.

That is, in general, the relationship between the generator output and the boiler-generated steam flow rate is approximately proportional, as indicated by the straight line LL in FIG.

On the other hand, if the minimum steam flow rate that enables stable operation of the boiler is Q ₁ , then the steam flow rate generated by the boiler cannot be made smaller than that steam flow rate Q ₁ , so the steam flow rate Q ₁
When the generator output is smaller than the generator output P ₁ corresponding to, the steam corresponding to the difference between the steam flow rate on the straight line LL corresponding to the generator output and the steam flow rate Q ₁ It directly flows into the condenser 9 via the bypass valve 4 and the low-pressure turbine bypass valve 10.

Further, the capacity of the turbine bypass system is set so as to substantially match the steam flow rate Q ₁ .

When starting the generator 11, first, in the state where the steam of the steam flow rate Q ₁ is being generated from the superheater 1, the steam control valve 2
Is gradually opened from the fully closed state as the set value of the piezoelectric output increases, and the high pressure turbine bypass valve 4 is gradually narrowed from the fully opened state.

At this time, the opening degree of the high-pressure turbine bypass valve 4 is controlled so that the sum of the flow rate of the steam passing through the steam control valve 2 and the flow rate of the steam passing through the high-pressure turbine bypass valve 4 becomes the steam flow rate Q ₁ .

Then, for example, when the high pressure turbine bypass valve 4 is in the fully closed state at the generator output P ₂ , the turbine bypass operation ends.

The flow rate control of the intercept valve 6 is performed as follows. The low-pressure turbine bypass valve 10 has a steam flow rate of the intercept valve 6 and a low-pressure turbine bypass valve 10.
The flow rate control is performed so that the sum of the steam flow rates of 1 and 2 becomes equal to the flow rate of the steam flowing out from the reheater 5.

That is, when the turbine speed-controlled operation is performed using the turbine bypass system, steam passes through the high-pressure turbine bypass valve 4 and is guided to the outlet of the high-pressure turbine 3, so compared with the case where the turbine bypass system is not used. , The outlet pressure of the high-pressure turbine 3, that is, the back pressure increases,
As a result, the flow rate of steam passing through the steam control valve 2 is reduced, so that the steam control valve 2, the high-pressure turbine 3, and the high-pressure piping system between the steam control valve 2 and the high-pressure turbine 3 are overheated.

In order to prevent this overheating, the steam flow rate of the intercept valve 6 becomes smaller than the steam flow rate of the steam control valve 2 during the turbine bypass operation.
The intercept valve 6 controls the flow rate. For example, the ratio between the steam flow rate of the steam control valve 2 and the steam flow rate of the intercept valve 6 is set to 2: 1.

On the other hand, when the turbine bypass operation is completed, the control mode of the intercept valve 6 is switched so as to perform the normal speed control.

That is, during the turbine bypass operation, the opening degree of the intercept valve 6 is set to an intermediate opening degree according to the flow rate control, and when the turbine bypass operation is completed, the opening degree of the intercept valve 6 is almost set for speed control. It is set to the fully open state.

In this way, when the turbine bypass operation is completed, the control mode of the intercept valve 6 is switched, and when the opening suddenly changes from the midway opening to full opening, the generator output suddenly changes. On the occasion,
The change rate of the opening degree of the intercept valve 6 is controlled so as not to exceed a certain value.

FIG. 5 shows a conventional example of a control device for performing such turbine bypass operation.

The generator output setting signal SO output from the generator output setter 15 is added to the plasma input terminal of the adder 16,
A generator output detection signal DO obtained by detecting the output of the generator 11 is added to the negative input terminal of the adder 16.

The output signal of the adder 16 is added as an output deviation signal SE to a load setter 17 composed of an integrator, and this load setter 17
Is applied to one plus input terminal of the adder 18 as a load setting signal SL, and is also applied to the intercept valve speed governor controller 19.

The turbine speed setting signal ST output from a speed setting device (not shown) is applied to the plus input end of the adder 20, and the turbine input obtained by detecting the speed of the turbine at the minus input end of the adder 20. Speed detection signal DT is added.

The output signal of this adder 20 is the turbine speed deviation signal TE
Is added to the intercept valve speed governor controller 19, multiplied by the speed adjustment gain via the speed adjustment gain multiplier 21, and then added to the other plus input terminal of the adder 18.

The output signal of the adder 18 is added to the steam control valve control device 22 and the intercept valve flow rate proportional controller 23 as a steam control valve flow rate command signal CR.

The intercept valve speed governor controller 19 is for controlling the flow rate of the intercept valve 6 on the basis of the load setting signal SL and the turbine speed deviation signal TE, and the speed control command signal CC thereof is a rate of change limit. Device 24, sequence control 25, and one switching connection 26a of switch 26.

The steam control valve controller 22 controls the steam control valve flow rate command signal CR.
The control signal LS controls the opening degree of the steam control valve 2 based on the control signal LS.

The intercept valve flow rate proportional controller 23 calculates a flow rate setting signal CI for setting the flow rate of the intercept valve 6 so as to have a constant ratio with the flow rate of the steam control valve 2 based on the steam control valve flow rate command signal CR. And its flow rate setting signal CI
Is applied to one switching connection end 27a of the switch 27 and is also applied to the tracking input end of the rate-of-change limiter 24 via the switch 28.

When the output signal of the rate-of-change limiter 24 follows the signal value applied to the tracking input terminal and the signal applied to the tracking input terminal is removed, the input signal is changed from the output signal at that time. To change the output signal at a rate of change within a certain range, and the output signal is applied to the sequence controller 25 and the other switching connection end 27b of the switch 27. There is.

The sequence controller 25 is an intercept valve speed governor controller.
Turbine control at startup is performed based on the speed control command signal CC output from 19 and the output signal of the change rate limiter 24, and signals from other elements such as the opening degree of the high-pressure turbine bypass valve 3. This sequence control device
The operation of the switches 26, 27 and the switch 28 is controlled by 25.

The output signal from the common terminal 27c of the switch 27 is
The output signal from the common terminal 26c of the switching device 26 is applied to the intercept valve control device 29. Intercept valve controller 29
Is for controlling the opening of the intercept valve 6 based on the signal input from the switch 26, and the control signal LI controls the opening of the intercept valve 6.

With the above configuration, when increasing the output of the generator 11, first, in order to perform the turbine bypass operation, the sequence controller 25 switches the switch 26, 27 to the switching connection terminals 26b, 2 respectively.
It operates on the 7a side and turns on the switch 28.

In this state, the generator output setting signal SO output from the generator output setting unit 15 rises in a predetermined change mode, whereby the load deviation signal SE output from the adder 16 becomes a signal with a positive sign. The load setting signal SL output from the load setting device 17 gradually increases.

On the other hand, until the turbine speed is set to the rated speed, the adder 20 outputs a turbine speed deviation signal TE with a positive sign.

Therefore, the steam control valve flow rate command signal CR output from the adder 18 gradually increases, whereby the flow rate of the steam control valve 2 increases. Further, the intercept valve flow rate proportional controller 23 outputs a flow rate setting signal CI so that the flow rate of the intercept valve 6 becomes a constant ratio with respect to the flow rate of the steam control valve 2, and this flow rate setting signal CI is a switching device. 27 and switch
It is added to the intercept valve control device 29 via the switch 26 and to the change rate limiter 24 via the switch 28.

Thus, as the flow rate of the steam control valve 2 increases, the opening degree of the intercept valve 6 increases and the flow rate increases.

Further, at that time, the output signal of the rate-of-change limiter 24 tracks the flow rate setting signal CI output from the intercept valve flow rate proportional controller 23. On the other hand, the intercept valve speed governor controller 19 calculates and outputs a speed governing command signal CC based on the turbine speed deviation signal TE and the load setting signal SL.

When turbine bypass operation is performed in this way,
As described above, the high-pressure turbine bypass valve 3 gradually closes, and the high-pressure turbine bypass valve 3 fully closes when the generator output reaches P ₂ .

This completed the turbine bypass operation,
The sequence control device 25 switches the switching device 27 to the switching connection end 27b side and turns off the switch 28 in preparation for switching the control operation of the intercept valve 6 to the speed control.

As a result, the output signal of the change rate limiter 24 becomes
It is added to the intercept valve controller 29 via 7,26.

Immediately after the switch 28 is turned off, the output signal of the rate-of-change limiter 24 has the same value as the flow rate setting signal CI output from the intercept valve flow rate proportional controller 23.
The speed change command signal CC output from the intercept valve speed control controller 19 changes at a change rate within a certain range.

Further, when the output value of the rate-of-change limiter 24 changes to the speed control command signal CC, the speed control command signal CC has changed to a signal value that almost fully opens the intercept valve 6, so that the intercept valve 6 is opened. The degree gradually changes from the halfway opening at the end of the turbine bypass operation to full opening.

Then, the output signal of the change rate limiter 24 is the speed control command signal CC.
When the state corresponding to the above condition is reached, the control switching preparation period ends, so the sequence control device 25 causes the switching device 26 to switch the switching connection terminal.
Switch to 26a side.

As a result, after that, the intercept valve speed governor controller
The speed control command signal CC output from 19 controls the speed of the intercept valve 6.

(Problems to be Solved by the Invention) However, such a conventional device has the following disadvantages.

That is, in general, the limit value of the change rate in the change rate limiter 24 is set so that the slope of the load increase due to the flow rate control of the intercept valve 6 becomes smaller in response to the load increase performed by the generator output setter 15. ing.

Therefore, for example, at the time when the opening degree of the intercept valve 6 is fully opened, the generator output by the generator output setter 15 changes to P ₃ which is larger than P ₁ (see FIG. 4 (b)), Therefore, since the opening degree of the intercept valve 6 when the generator output changes from P ₂ to P ₃ is not fully opened, the steam flowing out of the reheater 5 is passed through the low pressure turbine bypass valve 10 to the condenser 9. leak.

Therefore, in order to control the output of the generator 11 so as to match the generator output setting signal SO of the generator output setter 15, the flow rate AS passing through the low pressure turbine bypass valve 10
(See FIG. 4 (b)), it is necessary to generate extra steam from the boiler, which causes a problem that the plant efficiency is deteriorated.

Further, as described above, there is a disadvantage that the control system on the boiler side is adversely affected because the excessive steam flow rate is generated.

An object of the present invention is to solve the problems of the conventional apparatus as described above, to improve the plant efficiency, and to provide a turbine control apparatus that does not give disturbance to the boiler control.

[Configuration of the Invention] (Means for Solving the Problem) The present invention is directed to an intercept valve load controller for performing load control by an intercept valve based on a generator output deviation signal, and an intercept valve flow ratio control during bypass operation. The output signal of the intercept valve load controller is made to follow the output signal of the interceptor, and when the bypass operation is completed, the follow-up operation of the intercept valve load controller is stopped and the opening of the main steam control valve is maintained, and the intercept valve flow ratio controller Control signal of the intercept valve to the output signal of the intercept valve load controller, and when the output signal of this intercept valve load controller matches the output signal of the intercept valve speed governor controller, the intercept valve load control Switching the control signal of the intercept valve from the output signal of the regulator to the output signal of the intercept valve speed regulator Those having a control unit that.

(Operation) Therefore, when the control of the intercept valve is switched from the flow rate proportional control to the speed control, the steam control valve is kept at a constant opening until the intercept valve is fully opened. Since the load control is carried out at 1, the steam flow rate can be made constant, the plant efficiency is improved, and the boiler control is not adversely affected.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a turbine control device according to an embodiment of the present invention. In the figure, the same parts as those in FIG. 5 and the corresponding parts are designated by the same reference numerals.

The load deviation signal SE output from the adder 16 is applied to the intercept valve load controller 30 and the switch 31
It is added to the load setter 17 via.

The flow rate setting signal CI output from the intercept valve flow rate proportional controller 23 is applied to the tracking input terminal of the intercept valve load controller 30 via the switch 28.

The intercept valve load controller 30 is composed of an integrator that integrates the load deviation signal SE, and when a signal is applied to the tracking input end, the value of the output signal follows the signal value. When no signal is added to the tracking input terminal, the output signal at that time is used as a start value to start the integration operation of the load deviation signal SE. The output signal of the intercept valve load controller 30 is applied to the sequence controller 25 and the switching connection end 27b of the switch 27.

With the above configuration, when increasing the output of the generator 11, first, in order to perform the turbine bypass operation, the sequence controller 25 switches the switch 26, 27 to the switching connection terminals 26b, 2 respectively.
While operating on the 7a side, the switches 28 and 31 are turned on.

In this state, the generator output setting signal SO output from the generator output setting unit 15 rises in a predetermined change mode, whereby the load deviation signal SE output from the adder 16 becomes a positive load signal. , The load setting signal output from the load setting device 17 as it is added to the load setting device 17 via the switch 31.
SL gradually increases.

On the other hand, until the turbine speed is set to the rated speed, the adder 20 outputs a turbine speed deviation signal TE with a positive sign.

Therefore, the steam control valve flow rate command signal CR output from the adder 18 gradually increases, whereby the flow rate of the steam control valve 2 increases. Further, the intercept valve flow rate proportional controller 23 outputs a flow rate setting signal CI so that the flow rate of the intercept valve 6 becomes a constant ratio with respect to the flow rate of the steam control valve 2, and this flow rate setting signal CI is a switching device. 27 and switching group
It is added to the intercept valve control device 29 via the switch 26 and to the intercept valve load controller 30 via the switch 28.

As a result, as the flow rate of the steam control valve 2 increases, the opening degree of the intercept valve 6 increases and the flow rate increases (see FIGS. 2 (a) to (e)).

Further, at that time, the output signal of the intercept valve load controller 30 tracks the flow rate setting signal CI output from the intercept valve flow rate proportional controller 23. on the one hand,
The intercept valve speed governor controller 19 calculates and outputs a speed governing command signal CC based on the turbine speed deviation signal TE and the load setting signal SL.

When turbine bypass operation is performed in this way,
As described above, the high-pressure turbine bypass valve 3 gradually closes, and the high-pressure turbine bypass valve 3 fully closes when the generator output reaches P ₂ .

This completed the turbine bypass operation,
The sequence control device 25 switches the switch 27 to the switching connection end 27b side and turns off the switches 28 and 31 in preparation for switching the control operation of the intercept valve 6 to the speed control.

As a result, the load deviation signal SE is not added to the load setting device 17, the value of the load setting signal SL is held at the value at that time, and at this time, the turbine speed substantially matches the rated rotation speed. Therefore, the flow rate setting signal CR output from the adder 18 is almost held at the value at that time. Therefore, the steam flow rate of the steam control valve 2 is maintained at the value at the end of the turbine bypass operation.

Further, the output signal of the intercept valve load controller 30 is applied to the intercept valve control device 29 via the switches 27 and 26.

The output signal of the intercept valve load controller 30 is
Immediately after 28 is turned off, it has the same value as the flow rate setting signal CI output from the intercept valve flow rate proportional controller 23, and from that time point, the value of the output signal at that time is the start value,
The load deviation signal SE changes to an integrated value.

Therefore, the opening degree of the intercept valve 6 is set to an intermediate opening degree corresponding to the flow rate ratio control at that time point at the time of the turbine bypass operation end, and thereafter, the load deviation signal is set.
The SE is controlled to change to zero.

At this time, since the load deviation signal SE has a positive sign, the output signal of the intercept valve load controller 30 controls the steam flow rate of the intercept valve 6 in the direction of increasing the steam flow rate, thereby opening the intercept valve 6. The degree gradually changes from the opening degree at the end of the turbine bypass operation to the fully open direction.

On the other hand, the speed control command signal CC of the intercept valve speed control controller 19
By the time the output signal of the intercept valve load controller 30 changes to a value that fully opens the intercept valve 6, it has changed to a signal value that almost completely opens the intercept valve 6.

Therefore, the sequence control device 25 ends the control switching preparation period when the output signal of the intercept valve load controller 30 becomes in a state of matching the speed control command signal CC, that is, when the intercept valve 6 is fully opened. Then, the switching device 26 is switched to the switching connection end 26a side, and the switch 31 is turned on.

As a result, after that, the intercept valve speed governor controller
The speed control command signal CC output from 19 controls the speed of the intercept valve 6 and restarts the integral operation of the load setter 17 to restart the load control by the steam control valve 2.

In this way, in the present embodiment, during turbine bypass operation, load control is performed by the steam control valve 2 and the intercept valve 6 whose flow rate is controlled, and when the turbine bypass operation is completed, the steam control valve at that time is controlled. 2 is maintained, load control is performed by the intercept valve 6 until the intercept valve 6 is fully opened, and when the intercept valve 6 is fully opened, the load control of the steam control valve 2 is restarted and the intercept valve 6 is opened. To speed control. That is, in this case, the intercept valve 6 is fully opened in the state of the generator output P ₁ in FIG. 2 (a).

Therefore, during the period in which the opening degree of the intercept valve 6 changes from the middle opening degree to the full opening degree, the load control is performed only by the intercept valve 6 while maintaining the opening degree of the steam control valve 2, so that the steam generated from the boiler is generated. Can be used effectively for load control.

As a result, plant efficiency is improved and disturbance to the control of the boiler is prevented.

[Effects of the Invention] As described above, according to the present invention, when the turbine bypass operation is completed, the opening of the steam control valve is maintained at that time and load control is performed by the intercept valve so that the intercept valve is fully opened. At that time, the load control by the steam control valve is restarted, so that the steam usage condition becomes good in the state where the opening degree of the intercept valve shifts from the middle opening degree to full opening, and the plant efficiency is improved. Also,
The effect that the disturbance given to the boiler control can be largely controlled is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a turbine control device according to an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the device of FIG. 1, and FIG. FIG. 4A is a schematic configuration diagram showing an example of a turbine system including a turbine bypass system.
Is a graph showing an ideal mode of load control, FIG.
FIG. 5 is a graph for explaining the problem of the conventional device, and FIG. 5 is a block diagram showing an example of the conventional device. 17 …… Load setting device, 25 …… Sequence control device, 30 ……
Intercept valve load controller, 31 …… Switch.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F01D 17/20 F01D 17/20 H 19/00 19/00 P

Claims (1)

(57) [Claims] Claims: 1. An intercept valve and a bypass valve are provided in a steam system, and when the bypass operation is performed, an intercept valve flow rate controller for controlling the intercept valve proportionally to a flow rate proportional to the main steam control valve flow rate; In a turbine control device equipped with an intercept valve speed regulator that controls the intercept valve based on a load setting signal, an intercept valve load controller for performing load control by the intercept valve based on a generator output deviation signal, and During bypass operation, the output signal of the intercept valve load controller is made to follow the output signal of the intercept valve flow ratio controller, and at the end of bypass operation, the follow-up operation of the intercept valve load controller is stopped and the main steam control valve Holds the opening and outputs the intercept valve flow ratio controller Switching control signal intercept valve to an output signal of the intercept valve load controller from No.,
When the output signal of the intercept valve load controller coincides with the output signal of the intercept valve speed governor, the output signal of the intercept valve load controller changes from the output signal of the intercept valve speed regulator to the output signal of the intercept valve speed controller. A turbine control device comprising control means for switching control signals.