JP2564351B2 - Output control device for reactor plant - Google Patents

Description

TECHNICAL FIELD The present invention relates to an output control device for a nuclear reactor plant, and more particularly to a reactor plant suitable for application to an output control system for a boiling water nuclear power plant. The present invention relates to an output control device.

[Conventional technology]

Generally, multiple boiling water nuclear power plants (hereinafter BWR)
In the event of a large-scale power loss or load loss due to a lightning strike, etc. in a system with a Move to operation.

On the other hand, the turbine control device in the BWR plant has a pressure adjusting function that controls the reactor pressure according to the detected steam pressure signal, and a speed control function that controls the turbine output according to the detected turbine speed signal and load set value. It has a load adjusting function, and executes a cooperative control with the main steam control valve and the turbine bypass valve based on the signals obtained by these two functions. Further, when an abnormality occurs in the power system, the power load unbalance relay operates, the main steam control valve is rapidly closed, and the reactor pressure is controlled by opening / closing the turbine bypass valve. Such control is disclosed in JP-A-56
-145397 publication.

[Problems to be Solved by the Invention]

In the above-mentioned publication, the main steam control valve and the turbine bypass valve are rapidly closed by the operation of the power load unbalance relay when the power system is abnormal (for example, when the load is cut off due to lightning or the like). . But actually,
A high pressure turbine and a low pressure turbine are connected as a turbine, and steam discharged from the high pressure turbine is supplied to the low pressure turbine through an intercept valve. The main steam control valve is installed in the main steam pipe that guides the steam generated in the reactor pressure vessel of the BWR plant to the high-pressure turbine. The above-mentioned publication does not consider the opening / closing operation of the main steam control valve and the turbine bypass valve corresponding to the opening / closing operation of the intercept valve when the power system is abnormal.

However, the inventors have found that there is a new problem by examining the opening / closing of the intercept valve and the operation of the power load unbalance relay in correspondence with the opening / closing of the main steam control valve and the turbine bypass valve. . The details of the study at the BWR plant are explained below.

The power load unbalance relay is a measurement signal of electric current generated by a generator connected to the low-pressure turbine (generator current signal) and steam pressure discharged from the high-pressure turbine connected to the low-pressure turbine and supplied to the low-pressure turbine. (Hereinafter referred to as "intermediate steam pressure") is input as a measurement signal (intermediate steam pressure signal), and is activated when the difference between the generator current signal and the intermediate steam pressure signal falls below a predetermined value (for example, 40%). And then reset. The operation of the power load unbalance relay causes the operating oil pressure of the main steam control valve to drop rapidly and the main steam control valve to close rapidly, and at the same time, the load setting signal of the load setting device is set to zero.

The pressure controller inputs the pressure signal of the steam generated in the reactor pressure vessel of the BWR plant, the pressure setting signal, and the deviation signal, and outputs the total main steam flow rate signal. The speed controller inputs a deviation signal between the measured turbine rotation speed signal and the turbine rotation speed setting signal and outputs a turbine rotation speed control signal. Low-priority circuit is used for all main steam flow signals and speed /
A low level signal is selected from the load control signals and the main steam control valve flow rate request signal is output. The main steam control valve is
The opening degree is controlled based on the main steam control valve flow rate request signal. The speed / load control signal is obtained based on the turbine rotation speed control signal and the load setting signal.

Further, the opening degree of the turbine bypass valve is controlled based on the turbine bypass valve flow rate request signal, which is the deviation between the total main steam flow rate signal and the main steam control valve flow rate request signal.

The intercept valve that controls the flow rate of the steam guided from the high pressure turbine to the low pressure turbine is controlled by the intercept valve flow rate request signal. The flow rate request signal is obtained by correcting the control signal, which is the output signal of the intercept valve speed regulator inputting the deviation signal input to the speed regulator, based on the load setting signal from the load setting device.

The response of the BWR plant in the case where the power load unbalance relay does not operate and a partial load cutoff to the extent that the intercept valve is suddenly closed occurs in the power system will be described with reference to FIG.

When such partial load shedding occurs in the power system, the turbine speed signal will rise and the speed / load control signal will fall. When the turbine rotation speed increases by about 0.25 Hz, the speed / load control signal becomes less than or equal to the total main steam flow rate signal, and the low value priority circuit selects the speed / load control signal and outputs it as the main steam flow rate request signal (No. 8). Figure (A) dashed line). Therefore, the opening degree of the main steam control valve is reduced as the speed / load control signal decreases, and the main steam control valve flow rate decreases as shown by the solid line in FIG. 8 (A). Further, the bypass valve flow rate request signal has a positive value, the turbine bypass valve opens, and the turbine bypass valve flow rate rises as shown by the alternate long and short dash line in FIG. 8 (A). However, when the rate of increase in turbine rotational speed is large, the intercept valve is suddenly closed in order to cut off the main steam flow rate flowing from the high pressure turbine to the low pressure turbine in advance (two-dot chain line in FIG. 8A).

In the event as shown in FIG. 8, the main steam control valve closing operation is slightly delayed with respect to the decrease in the main steam control valve flow rate request signal (broken line in FIG. 8A) due to the increase in turbine rotation speed (8th operation). (Solid line in Figure (A)), and the turbine bypass valve
The deviation between the bypass valve flow rate request signal and the actual valve opening due to the main steam control valve flow rate request signal is 5% or more and the reactor output is 15%.
Due to the interlock of rapid opening, it will open rapidly.
Therefore, the main steam flow rate increases due to a mismatch between the main steam control valve flow rate (solid line in FIG. 8A) and the turbine bypass valve flow rate (dotted line in FIG. 8A) (FIG. 8). (C) (solid line), there is a possibility of reaching the scrum by exceeding the scram setting value of the main steam flow rate. Further, since the turbine rotation speed rapidly increases, the intercept valve closes rapidly, which causes the turbine rotation speed to decrease. Here, if the intercept valve is suddenly closed while the residual load is large, the turbine speed may fall below the low frequency trip set value and further decrease (FIG. 8 (D) solid line). In addition, the main steam control valve opens in the process of decreasing the turbine rotation speed (8th
The solid line in FIG. However, due to the operation characteristics of the main steam control valve, the main steam control valve closing operation continues even if the main steam control valve flow rate request signal changes to the open direction (Fig. 8 (A)), and the main steam control valve opens. The operation is delayed further. At this time, the closing operation of the turbine bypass valve is also performed (dashed line in FIG. 8A), but the turbine bypass valve flow rate request signal does not depend on the response of the main steam control valve, but the main steam control valve flow rate request signal. Therefore, the turbine bypass valve is closed although the main steam control valve is not opened. As a result, the reactor pressure rises (Fig. 8 (B)), the neutron flux most sensitive to this pressure fluctuation fluctuates (broken line in Fig. 8 (C)), and the neutron flux high scrum setting value can be reached. There is a nature.

Next, referring to FIG. 9, the BWR plant response when a partial load cutoff to the extent that the power load unbalance relay operates occurs in the power system will be described.

When an accident such as a lightning strike occurs in the electric power system and the load is lost, the frequency of the electric power system increases accordingly. In order to suppress the increase in the power system frequency, that is, the increase in turbine rotation speed, the power load unbalance relay is activated when the power system load is 40% or more and 40% / 10 milliseconds or less compared to the reactor output. However, the main steam control valve is suddenly closed by suddenly reducing the drive oil pressure of the main steam control valve (No. 9).
The solid line in FIG. At the same time, the load setting signal of the load setter becomes zero and the speed / load control signal becomes negative (zero in control) due to the operation of the power load unbalance relay. Therefore, the speed / load control signal preferentially passes through the low value priority circuit, and the main steam control valve flow rate request signal also becomes zero. Along with this, the total main steam flow rate signal becomes the turbine bypass valve flow rate request signal as it is, and the turbine bypass valve opens (one-dot chain line in FIG. 9A).

On the other hand, when the load setting becomes zero due to the operation of the power load unbalance relay and the turbine speed increases,
The intercept valve is controlled in the closing direction. However, in the case of a sudden load change like this event, the intercept valve is closed rapidly.

The series of operations suppresses an increase in the power system frequency.

After that, in the process of decreasing the turbine rotation speed,
The intercept valve gradually opens due to the action of the sudden closing reset when the opening deviation becomes 5% or less (two-dot chain line in FIG. 9 (A)). At this time, the main steam control valve is still fully closed, so if the intermediate steam pressure signal drops and the deviation from the generator current signal falls below 40%, the power load unbalance relay will be automatically reset. Due to the reset of the power load unbalance relay, the four main steam control valve quick closing actuating solenoid valves are reset after 1, 2, 3 and 4 seconds respectively. In addition, the load setting is a certain value after reset (for example, 20%)
When the turbine speed 8 drops below 100.8%, the main steam control valve opens again (solid line in FIG. 9 (A)).

In the above operation, if the turbine speed falls below 100% before the power load unbalance relay resets, only the turbine bypass valve is closed because the main steam control valve is not reset rapidly. Figure 9 (A)
(Dashed-dotted line) causes mismatches in the main steam control valve flow rate and the turbine bypass valve flow rate, and the reactor pressure rises due to the characteristic difference between the main steam control valve opening operation and the turbine bypass valve closing operation (Fig. 9). Along with the solid line in (B), the reactor water level decreases (broken line in FIG. 9B) and there is a possibility of scramming.

Also, it takes time to reset the main steam control valve and intercept valve, and the opening start time of these valves is slow.If the turbine load remains large, the opening speed of the main steam control valve and intercept valve is slow. Therefore, the turbine speed may suddenly drop and reach a low frequency trip (Fig. 9 (D)).

An object of the present invention is to provide an output control device for a steam generation plant, which can continue operation of the steam generation plant while avoiding unnecessary plant stop even when turbine speed fluctuations due to power system disturbance occur and an adjustable operation is performed. is there.

[Means for solving the problem]

The present invention limits the system load to a predetermined value in order to suppress a decrease in turbine speed when a partial load cutoff occurs in the power system, and changes the opening / closing speed of the bypass valve (bypass valve flow rate request signal). Is limited based on the rate of change of the control valve flow rate request signal.

[Action]

It is possible to suppress scram due to a decrease in turbine speed when a partial load is cut off, and suppress scram due to a pressure high, a main steam flow rate, a high neutron flux, etc. due to a difference in opening / closing speed of the regulator valve and the bypass valve.

〔Example〕

An output control device of a reactor plant having a turbine control device and a system stabilizing device, which is a preferred embodiment of the present invention applied to a BWR plant, will be described with reference to FIGS. 1 to 5.

 First, the outline of the system stabilizing device will be described with reference to FIG.

In the case of a large-scale power loss or load loss in the power system, the power system stabilizer 55 urgently balances the supply and demand to maintain stable operation of the power system.
The power flow of each main line 70 and each load line 69 detected at is always taken in. When the power supply is dropped and the load is dropped, the system stabilizing device 55 cuts off the minimum load 69 necessary to prevent the entire system from being destroyed. 63-68 are also circuit breakers.
In the BWR plant 57, when the power load unbalance relay is activated due to the loss of load, select control rod insertion (SR
I) The operation signal 72 is taken in and the system load connected to the BWR plant 57 is limited by opening the circuit breakers 58 to 62 so that the system load becomes a predetermined value. Selective control rods are control rods that have been preselected for rapid insertion into the core of a nuclear reactor during turbine trips or sudden load interruptions.
The number of selective control rods is set so that the operation can be continued at a low output without stopping the reactor.

The interlock of system load limitation will be described with reference to FIGS. 1 and 2. These interlocks are provided in the system stabilizing device 55.

FIG. 1 shows an interlock that operates when a load interruption occurs and the power load unbalance relay operates. That is, the system stabilizer 55 determines that the SRI operation signal and the load amount of the BWR plant at that time have a certain value (for example, 2
0%) and above, and power load unbalance relay 23
When the condition that the load at the time of operating is above a certain value (for example, 70%) is met, a predetermined time delay (for example, 1.
A certain number of circuit breakers connected to the load line 69 (circuit breaker 58-
Open some 62) to limit the load.

FIG. 2 shows a load limiting interlock that operates when the load is cut off, the power load unbalance relay 23 does not operate, and the intercept valve 48 closes rapidly. The system stabilizer 55 uses the intercept valve abrupt closing signal and the load amount of the BWR plant when the load is cut off at a certain value (for example, 60%) or more, and when the condition that the SRI does not operate is satisfied. By opening some of the circuit breakers 58 to 62 with a certain time delay (for example, 1.5 seconds), the system load is limited to a certain predetermined value (for example, 20%).

In Fig. 1 and Fig. 2, the initial load is the ratio of the load connected to the generator of the BWR plant to the total load before the load is cut off, and the residual load is the load that is alive after the load is cut off. It is a percentage of the total load. The system stabilizer 55 includes the current transformers 75 to 79 provided on each load line 69.
Input the output of to obtain the initial load and residual load.

Next, the outline of the BWR plants 56 and 57 shown in FIG. 3 will be described with reference to FIGS. The steam generated in the reactor pressure vessel 40, which is a steam generator, is sent to the high-pressure turbine 41 via the main steam pipe 45, and is further guided to the low-pressure turbine 42 via the crossaround pipe 47. The steam exhausted from the low-pressure turbine 42 is condensed in the condenser 43 into water. Although not shown, this condensed water is returned to the reactor pressure vessel 1 through a water supply pipe. The main steam pipe 45 is provided with a steam control valve 46, and the cross-around pipe 47 is provided with an intercept valve 48. Main steamer 45 upstream of steam control valve 46
The bypass pipe 49 branched from is connected to the condenser 43. A turbine bypass valve 50 is provided in the bypass pipe 49. The rotary shaft of the high-pressure turbine 41 and the rotary shaft of the low-pressure turbine 42 are connected. A generator 44 is detachably connected to the rotary shaft of the low-pressure turbine 42. Pressure gauge
The output signals of 51, 52, turbine speed detector 53 and ammeter 54 are input to the turbine controller 13.

A detailed configuration of the turbine control device 13 is shown in FIG. The operation of the turbine control device 13 will be described in detail below. Pressure gauges 51 and 52 are installed in the main steam pipe 45 and the crossaround pipe, respectively. The pressure gauge 51 may be attached to the reactor pressure vessel 1. Reference numeral 53 is a turbine speed detector that detects the rotation speed of the turbine, and 54 is an ammeter.

13 In the turbine control device, the pressure gauge 51 measures the vapor pressure discharged from the reactor pressure vessel 40. The adder 55 obtains the deviation between the pressure signal 1 measured by the pressure gauge 51 and the preset pressure setting value 2. This deviation signal is input to the pressure regulator 4 via the filter circuit 3. The pressure regulator 4 produces the total main steam flow rate signal 5 from the deviation signal. On the other hand, the deviation between the turbine speed signal 8 measured by the turbine speed detector 53 and the turbine speed set value 9 is obtained by the adder 56. The obtained deviation signal 10 is input to the speed adjuster 11. The speed adjuster 11 outputs a turbine speed control signal 12 according to the input deviation signal. The speed control signal 12 is a load set value which is an output signal of the load setter 15.
14 is added by the adder 57 and becomes the speed / load control signal 13.

The total main steam flow rate signal 5 and the speed / load control signal 13 are input to the low value priority circuit 26. The low value priority circuit 26 selects a low value from those signals and outputs the selected signal as the regulating valve flow rate request signal 27. The opening degree of the steam control valve 46 is controlled by the control valve flow rate request signal 27.

The power load unbalance relay 23 inputs the intermediate steam pressure signal 24 which is the output of the pressure gauge 52 and the generator current signal 25 which is the output of the ammeter 54, and when the difference between these signals exceeds a predetermined value. The operation signal 22 is output. The pressure gauge 52
The steam pressure in the cross-around tube 47 is measured, and this measured value is output as the intermediate steam pressure signal 24. Ammeter 54
The current generated by the generator 44 is measured and this measured value is output as the generator current signal 25. The above-mentioned operation signal 22 is input to the load setting device 15, the instantaneous operation time-limit recovery circuit 28, and the change rate limit switching device 34, respectively.

The opening degree of the turbine bypass valve 50 is controlled based on the bypass valve flow rate request signal 7 output from the adder 58.
The adder 58 subtracts the steam control valve flow rate subtraction signal 33 and the chattering prevention bias signal 6 from the total main steam flow rate signal 5 to obtain the bypass valve flow rate request signal 7. The steam control valve flow rate subtraction signal 33 is output from the change rate limiter 32, and the function of the change rate limiter 32 will be described later.

In the BWR plant, the reactor power is adjusted by the amount of voids (vapor bubbles) in the core, so the neutron flux reacts sensitively to pressure changes. Therefore, during normal operation, the steam control valve 46 is preferentially controlled by the total main steam flow rate signal 5 based on the pressure signal 1. The load setting value 14 of the load setting device 15 is set to be 10% higher than the total main steam flow rate signal so that the steam control valve 46 does not operate in response to a relatively small change in turbine speed. Therefore, the speed control signal 12 is -10%
The steam control valve 46 does not respond to a turbine speed increase within (generally, the speed regulation rate is a 100% control signal / 5% speed change and corresponds to 0.25 Hz in the case of 50 Hz).
The steam control valve 46 is controlled by the total main steam flow rate signal 5, and pressure control is preferentially performed. On the other hand, for a turbine speed increase (that is, a frequency increase of 0.25 Hz or more) such that the speed / load control signal 13 decreases by 10% or more, the speed / load control signal 13 becomes smaller than the total main steam flow rate signal 5. .
Therefore, the steam control valve 46 is controlled and throttled by the speed / load control signal 13.

The excess steam generated by the throttle operation of the steam control valve 46 is supplied to the turbine bypass valve by the bypass valve flow rate request signal 7.
When the valve 50 is opened, it is directly discharged to the condenser 43. In this way, by cooperating the steam control valve 46 and the turbine bypass valve 50, the BWR plant operation can be stably continued with almost no change in the reactor pressure.

Further, the opening degree control of the intercept valve 48 for controlling the flow rate of the steam guided from the high pressure turbine 41 to the low pressure turbine 42,
This is performed as follows. The deviation signal 10 output from the adder 56 is input to the intercept valve speed regulator 17. The intercept valve speed regulator 17 outputs a control signal 18 corresponding to the deviation signal 10. The adder 59 has a control signal 1
8, add the control signal 19 obtained by multiplying the load set value 14 by the intercept valve adjustment gain 16 and the open bias signal 20 of the intercept valve, and obtain the intercept valve flow rate request signal 21
Is output. The opening and closing of the intercept valve 48 is controlled based on the intercept valve flow rate request signal 21.

However, during normal operation, the open bias signal 20 is set to 100%, and the control signal obtained by multiplying the adjustment gain 16 is set to a large positive value. It is always fully open, and the steam flow rate sent to the turbine is controlled by the steam control valve 46.

Next, the instantaneous operation time-limit recovery circuit 28, the speed / load signal switching circuit 29, and the speed load limiter 30 that constitute the turbine control device 13 will be described. Instantaneous operation time recovery circuit 28
The speed / load signal switching circuit 29 is instantly switched by the operation signal 28 output when the power load unbalance relay 23 operates, and the power load unbalance relay 23 is reset and the operation signal 28 is no longer output. At some time after that, the speed / load signal switching circuit 29 is switched back to the original state. The speed / load limiter 30 uses the set value of 0% as the speed / load setting signal 31 when the speed / load signal switching circuit 29 is switched by the operation signal 22 (when the power load unbalance relay 23 operates). The value is output to the low value priority circuit 26, and when the speed / load signal switching circuit 29 is switched to the original state (when the power load unbalance relay 23 has been reset for a predetermined time), the set value of 110% is set. The speed / load setting signal 31 is output to the low value priority circuit 26.

The change rate limiter switching circuit 34 uses a steam control valve flow rate request signal.
It controls the output signal of the rate-of-change limiter 32 to which 27 is input. That is, the change rate limiter switching circuit 34, when the operation signal 22 or the turbine trip generation signal 35 is not input, as the steam control valve flow rate subtraction signal 33 limiting the rate of change of the steam control valve flow rate request signal 27. Output from the rate-of-change limiter 32, and actuation signal 22 or turbine trip generation signal
When 35 is input, the rate-of-change limiter 32 is configured so that the rate-of-change signal 27 of the steam control valve is not limited to the rate-of-change but directly output from the rate-of-change limiter 32 as the signal 33 of subtracting the flow rate of the steam-controlling valve.
Control. During normal operation of the BWR plant, the rate-of-change limiter 32 always operates the rate-of-change limiting function described above.

A specific operation of the present embodiment configured as above will be described.

First, when the power load unbalance relay 23 does not operate and there is a load cutoff that causes the intercept valve 48 to close rapidly, that is, when the load cutoff amount is 20% to 40%. The plant response of BWR in is explained. In such load shedding,
The rate-of-change restrictor 32 outputs a steam control valve flow rate subtraction signal 33 subjected to rate-of-change restriction. In this case, since the power load unbalance relay 23 does not operate, the speed / load limiter 30 outputs the speed / load setting signal 31 whose setting value is 110% and 110%. In addition, the change rate limit switch 34
Does not work because there is no input signal, so change rate limiter
32 continues to output the steam control valve flow rate subtraction signal 33 whose rate of change is limited.

Figure 6 shows the BWR plant response at this time. Speed / load control signal by increasing turbine speed due to load shedding
12 drops and the speed / load control signal 12 falls below the total main steam flow signal 5. From this point on, the steam control valve 46 is controlled and throttled by the speed / load control signal 12 selected by the low value priority circuit 26. The actual opening / closing speed of the steam control valve 46 and the opening / closing speed of the turbine bypass valve 50 have a considerable difference, but the steam control valve flow rate request signal to be subtracted from the total main steam flow rate signal 5
Since the change rate limiter 32 applies a change rate limit to 27,
The turbine bypass valve 50 does not suddenly open and the mismatch between the steam control valve flow rate and the turbine bypass valve flow rate becomes small (Fig. 6 (A)), and the fluctuations of the main steam flow rate and neutron flux become small (Fig. 6). (C)). Therefore, it is possible to avoid unnecessary main steam isolation valve closing scrum and high neutron flux high scrum due to a large main steam flow rate.

Also, after the hold time of 1.5 seconds by the intercept valve rapid closing signal, the operation of the interlock (Fig. 2) that limits the system load to 20%, the low frequency trip due to the decrease of turbine speed and the turbine trip due to overspeed. Can be avoided (if the load is immediately limited by the intercept valve abrupt closing signal, the turbine speed will increase once and may reach the turbine trip).

When the power load unbalance relay 23 operates, the rapid operation solenoid valve is excited to rapidly reduce the hydraulic pressure of the steam control valve 46, thereby rapidly closing the steam control valve 46. At the same time, the operation signal 22 causes the load setting value 14 of the load setter 15 to be zero, and the speed / load control signal 13 to be negative (zero for control). Therefore, the speed / load control signal 13 passes through the low value priority circuit 26.

Also, the change rate limiter switching device 34 is activated by the operation signal 22 output from the power load unbalance relay 23,
The rate-of-change limiter 32 deactivates the function of limiting the rate of change. Therefore, the speed / load control signal (zero) 13 which is the steam control valve flow rate request signal 27 output from the low value priority circuit 26 is input to the adder 58 as it is. The bypass valve flow rate control signal 7 (bypass valve full open signal) obtained by correcting the total main steam flow rate signal 5 with the same value of the speed / load control signal 13 causes the turbine bypass valve 50 to rapidly open (valve open). The deviation between the control signal and the control signal is 5% or more).

After that, due to the decrease in the reactor output due to the insertion of the selective control rods and the influence of the operation of other plants, the turbine speed decreases and falls below the set value 9. If the turbine speed falls below the set value 9 before the power load unbalance relay 23 is reset, the speed / load control signal 13 changes from positive to negative. On the other hand, the total main steam flow rate signal 5 has a maximum value of 110% due to the pressure increase due to the main steam flow rate mismatch due to the difference in valve characteristics when the steam control valve is rapidly closed and the turbine bypass valve is rapidly opened. Therefore, in the conventional device, the speed / load control signal 13
Becomes the steam control valve flow control signal 27 as it is and tries to control the steam control valve to open and to close the turbine bypass valve, but only the turbine bypass valve 50 is throttled because it is before the steam control valve rapid closing reset. Result
High pressure could lead to scrum. However, according to this embodiment, the operation signal of the power load unbalance relay 23 is
22 activates the instantaneous operation time-return circuit 28, and the switching circuit 29
Accordingly, the speed load setting signal 31 output from the speed / load limiter 30 becomes zero. Therefore, the power load unbalance relay 23 is reset and the speed load setting signal of the speed / load limiter 30 is set by the instantaneous operation time limit reset circuit 28 for a period of 1 second after the steam control valve rapid closing reset is started.
Since 31 is held at zero, the steam control valve flow rate request signal 27 is also held at zero, only the turbine bypass valve 50 is throttled, and the high pressure scram is not reached.

Further, due to the reset of the power load unbalance relay 23, the rate-of-change limiter 32 operates again to start the limiting operation.Therefore, the opening operation of the steam control valve 46 and the turbine bypass valve after the reset of the power load unbalance relay 23 are started. The difference between the closing motions of 50 becomes small, and high pressure scrum and low water level scrum due to mismatching of both are avoided.
Furthermore, by the operation of the power load unbalance relay,
After a holding time of 1.0 second, by operating the interlock (FIG. 1) that limits the system load to 20%, low frequency trips and turbine trips can be avoided as in the above example.

As described above, according to the present embodiment, even if any load cutoff due to system disturbance occurs, the atomic plant can be stably operated continuously while avoiding unnecessary scrum.

That is, according to the present embodiment, the opening / closing speed is changed when the steam control valve and the turbine bypass valve are opened / closed due to the turbine speed fluctuation caused by the system load disturbance such as the operation of the power load unbalance relay or the system disturbance other than the turbine trip. Since the rate of change is limited to the steam control valve flow rate request signal in accordance with the slower steam control valve, the deviation between the sum of the turbine bypass valve flow rate and the steam control valve flow rate and the total steam flow rate request signal becomes small. Therefore, fluctuations in reactor pressure can be suppressed,
Unnecessary scrum can be avoided.

Further, even when the load is cut off such that the power load unbalance relay 23 operates, unnecessary scrum can be avoided by the speed / load limiting function, the change rate limiting switching function, and the system load limiting.

This embodiment can be applied to other steam generating plants such as a pressurized water reactor plant and a thermal power plant. BWR
The reactor pressure vessel of a plant is a steam generator in a pressurized water reactor plant and a boiler in a thermal power plant.

〔The invention's effect〕

As described above, the present invention allows stable continuous operation of the reactor plant by limiting the load to within a predetermined capacity even if any system disturbance occurs, so the system disturbance resistance of the steam generation plant is greatly increased. There is an effect that the operating rate can be improved by improving

[Brief description of drawings]

1 and 2 are incorporated in the system stabilizing device of FIG. Fig. 3 is an interlock diagram at the time of load limitation, Fig. 3 is a block diagram of the output control device of the steam generating plant according to one embodiment of the present invention, Fig. 4 is a block diagram of the BWR plant of Fig. 3, and Fig. 5 is FIG. 4 is a detailed configuration diagram of the turbine control device, FIG. 6 is a characteristic diagram showing a BWR plant response when a system disturbance to the extent that the power load unbalance relay does not operate in the embodiment of FIG. 1, and FIG. FIG. 8 is a characteristic diagram showing the BWR plant response when the power load unbalance relay operates in the embodiment shown in FIG. 1, and FIG. 8 is a characteristic diagram of the turbine control device of the conventional BWR plant under the same conditions as in FIG. FIG. 9 is a characteristic diagram of a turbine control device for a conventional BWR plant under the same conditions as in FIG. 7. 4 ... Pressure regulator, 11 ... Speed regulator, 13 ... Turbine controller, 15 ... Load controller, 17 ... Intercept valve speed regulator, 23 ... Power load unbalance relay,
26 …… Low value priority circuit, 28 …… Instantaneous operation time recovery circuit, 29
...... Speed / load signal switching circuit, 30 …… Speed load limiter,
32 …… Change rate limiter, 34 …… Change rate limiter switching circuit, 40
...... Reactor pressure vessel, 41 ...... High pressure turbine, 42 ...... Low pressure turbine, 46 …… Steam control valve, 48 …… Intercept valve, 50 …… Turbine bypass valve, 51,52 …… Pressure gauge, 53
…… Turbine speed detector, 54 …… Ammeter, 55 …… Grid stabilization device.

Claims (1)

(57) [Claims] 1. A pressure regulator that outputs a total main steam flow rate signal based on a deviation between a main steam pressure of a reactor and a pressure set value, and a speed / load request based on a deviation between a turbine rotation speed and a speed set value. A speed regulator that outputs a signal, and a signal selection unit that outputs a low-value signal among the main steam flow rate signal and the speed load request signal to output as a control valve flow rate request signal for controlling the control valve opening degree, Change rate limiting means for limiting the rate of change of the control valve flow rate request signal, and a bypass valve opening degree for subtracting the output signal of the change rate limiting means from the total main steam flow rate signal to adjust the bypass amount of the main steam. A subtraction means for outputting a bypass valve flow rate request signal for controlling the load, and a system stabilizing device for limiting the load of the power system to a predetermined value when the partial load of the power system of the generator driven by the turbine is cut off. , The part When the power load unbalance relay that operates when the load is cut off and the power load unbalance relay are activated, the change rate limiting means limits the rate of change of the regulator valve flow rate request signal during the relay operation period. An output control device for a nuclear reactor plant, comprising: a change rate limit switching means for canceling the change rate.