JPH01227997A - Device and method for controlling output of nuclear reactor plant - Google Patents

Abstract

PURPOSE:To avoid unnecessary stoppage of a steam producing plant even when the turbine speed fluctuates by sending an open signal to a breaker in accordance with the load quantities before and after the load is disconnected and a selection controlling rod actuating signal. CONSTITUTION:When load disconnection occurs and a power load unbalance relay is actuated, a system stabilizing device 55 limits the load by opening a prescribed number of breakers (some of 58-62) connected with a load line so that the system load can become a certain value (for example, 20%) a prescribed time (for example, 1.0sec) under a condition where selection controlling rod insertion (SRI) actuating signals 71 and 72 are available and the then load quantity of a BWR plant is a certain value (for example, 20%) or higher and the load at the moment when the power load unbalance relay is actuated is a certain value (for example, 70%) or higher. Therefore, even when the turbine speed fluctuates due to a disturbance in a power system and the turbine speed is to be reduced to a moderate speed, the operation of a steam producing plant can be continued by avoiding unnecessary stoppage of the plant.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an output control device for a nuclear reactor plant and an output control method thereof, and is particularly suitable for application to an output control system for a boiling water nuclear power plant. The present invention relates to an output control device and an output control method for a nuclear reactor plant.

rPrior art] In general, multiple boiling water nuclear power plants (hereinafter referred to as BWR)
In the event of a large-scale power outage or load drop due to a lightning strike, etc., in a system with a BWR plant (called a plant), the PSS will disconnect the BWR plant from the grid to prevent oversupply and sequentially shut down the plant or shift to isolated operation within the plant.

On the other hand, the turbine control device in a BWR plant has a pressure adjustment function that controls the reactor pressure according to the detected steam pressure signal, and a speed/speed control function that controls the turbine output according to the detected turbine speed signal and load setting value. It has a load adjustment function, and executes cooperative control with the main steam control valve and the turbine bypass valve based on signals obtained by both functions. Furthermore, when an abnormality occurs in the power system, the power load imbalance relay operates, the main steam control valve is suddenly closed, and the reactor pressure is controlled by opening and closing the turbine bypass valve. This kind of control was developed in Japanese Unexamined Patent Publication No. 5
6-145397.

(Problem to be Solved by the Invention) The above-mentioned publication discloses that when an abnormality occurs in the power system (for example, when a load is cut off due to a lightning strike, etc.), the power load imbalance relay operates to quickly close the main steam control valve and the turbine bypass valve. However, in reality, the turbine is a high-pressure turbine and a low-pressure turbine, and the steam discharged from the high-pressure turbine is supplied to the low-pressure turbine via an intercept valve. The valve is installed in the main steam piping that guides the steam generated in the reactor pressure vessel of the BWR plant to the high-pressure turbine. The opening and closing operations of the control valve and the turbine bypass valve are not considered.

However, by examining the correspondence between the opening and closing of the intercept valve and the operation of the power load unbalance relay, and the opening and closing of the main steam control valve and the turbine bypass valve, the inventors discovered that there was a new problem. The details of the study in the BWR plant will be explained below.

The power load unbalance relay measures the current measurement signal (generator current signal) generated in the generator connected to the low-pressure turbine and the 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"), and the generator is activated when the difference between the generator current signal and the intermediate steam pressure signal becomes less than a predetermined value (for example, 40%). will be reset. Due to the operation of the power load unbalance relay, the working oil pressure of the main steam control valve rapidly decreases, and the main steam control valve suddenly closes, and at the same time, the load setting signal of the load setting device is set to zero.

The pressure regulator inputs a pressure signal of steam generated in the reactor pressure vessel of the BWR plant, a pressure setting signal, and a deviation signal, and outputs a total main steam flow rate signal.

The speed regulator 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. The low value priority circuit selects a signal with a low level from among the total main steam flow rate signal and the speed/load control signal and outputs a main steam control valve flow rate request signal. The opening degree of the main steam control valve is controlled based on the main steam control valve flow rate request signal. Note that 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.

An intercept valve that controls the flow rate of steam led from the high pressure turbine to the low pressure tanibin is controlled by an intercept valve flow rate request signal. This flow rate request signal is obtained by correcting the control signal, which is the output signal of the intercept valve speed regulator, which inputs 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 when a partial load cutoff occurs in the power system to the extent that the power load unbalance relay does not operate and the intercept valve suddenly closes will be described using FIG. 8.

When such a partial load shedding occurs in a power system, the turbine rotational speed signal increases and the speed/load control signal decreases. When the rotational speed of the turbine increases by about 0.25 Hz, the speed/load control signal becomes less than the total main steam flow rate signal,
The low value priority circuit selects the speed/load control signal and outputs it as the main steam flow rate request signal (dashed line in Fig. 8 (A)). Therefore, the opening degree of the main steam control valve changes as the speed/load control signal decreases. 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 becomes a positive value, the turbine bypass valve opens, and the turbine bypass valve flow rate increases as shown by the dashed line in FIG. 8(A). However, if the rate of increase in the turbine rotational speed is large, the intercept valve closes suddenly in order to proactively cut off the flow of main steam flowing from the high-pressure turbine to the low-pressure turbine (see Figure 8).
A).

In the event shown in Figure 8, the main steam control valve flow rate request signal decreases due to an increase in the rotational speed of the turbine (Figure 8 (A)).
(broken line), the main steam regulator valve closing operation is slightly delayed (solid line in Figure 8 (A)), and the turbine bypass valve has a slight delay between the bypass valve flow rate request signal accompanying the main steam regulator flow rate request signal and the actual valve opening. An interlock will cause the reactor to close suddenly when the temperature deviation is 5% or more and the reactor output is 15% or more. Therefore, the main steam flow rate increases due to the mismatch of i between the main steam control valve flow rate (solid line in Figure 8 (A)) and the turbine bypass valve flow rate (-dotted chain line in Figure 8 (A)). (solid line in (C)), there is a possibility that the scram setting value for the large main steam flow rate will be exceeded and the scram will be lost.

Furthermore, since the turbine rotational speed increases rapidly, the intercept valve closes rapidly, thereby decreasing the turbine rotational speed.

Here, if the intercept valve suddenly closes when the train load is large, the turbine speed may fall below the low frequency trip setting value and further decrease (solid line in Figure 8 (D)).
Further, in the process of decreasing the turbine rotational speed, the main steam control valve opens (solid line in FIG. 8(A)). However, due to the operating characteristics of the main steam regulating valve, even if the main steam regulating valve flow rate request signal changes to the opening direction, the main steam regulating valve continues to close (Fig. 8 (A)'). The opening operation will be delayed further.

At this time, the turbine bypass valve is also closed (-dotted line in Fig. 8 (A)), but the turbine bypass valve flow rate request signal is not based on the response of the main steam control valve, but the main steam control valve flow rate request signal is The turbine bypass valve is closed even though the main steam control valve is not opened because it only follows the change in the signal. As a result, the reactor pressure increases and Figure 8 (
B)) The neutron flux, which is most sensitive to this pressure variation, fluctuates (dashed line in Figure 8(C)) and may reach the neutron flux high scram set value.

Next, with reference to FIG. 9, a description will be given of the BWR plant response when a partial load shedding occurs in the power system to the extent that the power load unbalance relay is activated.

If an accident such as a lightning strike occurs in the power system and the load is lost,
As a result, the frequency of the power system will increase.

In order to suppress this increase in power system frequency, that is, the increase in turbine rotation speed, a power load imbalance relay is activated when the power system load is 40% or more and less than 40%/10 milliseconds compared to the reactor output. However, by rapidly decreasing the opening hydraulic pressure of the main steam regulating valve, the main steam regulating valve is suddenly closed (solid line in FIG. 9(A)). At the same time, the load setting signal of the load setting device becomes zero due to the operation of the power load unbalance relay, and the speed/load control signal becomes negative (zero in terms of control). Therefore, the speed/load control signal passes through the low value priority circuit with priority, and the main steam regulator flow rate request signal also becomes zero. Accordingly, the total steam flow rate signal directly becomes the turbine bypass valve flow rate request signal, and the turbine bypass valve opens (--dotted chain line in FIG. 9(A)).

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 sudden load fluctuations like this one, the intercept valve is suddenly closed.

Through a series of operations, the increase in power system frequency is suppressed.

Thereafter, in the process of decreasing the turbine rotational speed, the intercept valve gradually opens due to the action of the quick close reset when the opening deviation becomes 5% or less (Figure 9 (A)).
(two-dot chain line), the main steam control valve is still fully closed at this time, so when the intermediate steam pressure signal decreases and the deviation from the generator current signal becomes 40% or less, the power load unbalance relay automatically activates. will be reset. By resetting the power load unbalance relay, the four main steam control valve quick-closing solenoid valves are reset after 1, 2, and 3.4 seconds, respectively. 'Also, the load setting will be set to a certain value (
For example, the turbine speed 8 is reset to 10%).
When it drops below 0.8%, the main steam control valve opens again (solid line in Figure 9(A)).

In the above operation, if the turbine rotation speed falls below 100% before the power load imbalance relay is reset, only the turbine bypass valve is closed because the main steam control valve has not yet been reset to sudden closing ( Figure 9 (A)
This causes a mismatch between the main steam control valve flow rate and the turbine bypass valve flow rate, and the reactor pressure increases due to the difference in characteristics between the main steam control valve opening operation and the turbine bypass valve closing operation (9th dotted line). (solid line in Figure 9(B)), the reactor water level will decrease (broken line in Figure 9(B)), and there is a possibility of scram.

In addition, it takes time to reset the main steam control valve and intercept valve, and the opening time of these valves is slow.
If the turbine load remains large, the opening speed of the main steam control valve and the intercept valve is slow, so the turbine speed may drop suddenly and lead to a low frequency trip (FIG. 9(D)).

An object of the present invention is to provide an output control device and an output control method for a steam generation plant that can continue operation of the steam generation plant while avoiding unnecessary plant stoppages even when turbine speed fluctuations occur due to power system disturbances and the operation is increased or decreased. Our goal is to provide the following.

[Means to solve the problem]

The above purpose is to provide a plurality of load detection means installed in each power system to detect the amount of load, and to detect the amount of load before load shedding and the amount of load after load shedding, which are determined based on the outputs of these load detection means. , and means for outputting an open signal to a circuit breaker provided in the power system in order to limit the system load to a predetermined value based on the selective control activation signal.

[Effect]

Since the capacity of other loads connected to the generator can be limited to a predetermined value or less during load shedding, the operation of the nuclear reactor plant can be continued.

〔Example〕

An output control device for a nuclear reactor plant having a turbine control device and a system stabilization device, which is a preferred embodiment of the present invention applied to a BWR plant, will be explained based on FIGS. 1 to 5.

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

System stabilization device! ! 55 is a current transformer 75 that is used to urgently balance supply and demand and continue stable operation of the grid in the event of a large-scale power outage or load drop in the power system.
The power flow of each main line 70 and each load line 69 detected at points 84 to 84 is always taken in.

Such a system stabilizing device 55 cuts off the minimum necessary load 69 in order to prevent the entire system from being destroyed in the event of power failure or load failure. 63 to 68 are also circuit breakers. BWR
In plant 57, when the power load imbalance relay is activated due to load drop, the selective control insertion (S R
I) The circuit breakers 58 to 62 receive the operating signal 72 and set the system load connected to the BWR plant 57 to a predetermined value.
Limit by opening. Selective control rods are control rods that are preselected for rapid insertion into the reactor core during a turbine trip or sudden load shedding. The number of selective control valves is determined so that the reactor can continue operating at low output without shutting down.

The above-mentioned system load limiting interlock is shown in Figures 1 and 2.
This will be explained using figures. These interlocks are provided within the system stabilizer 55.

FIG. 1 shows an interlock that is activated when a load shedding occurs and the power load imbalance relay is activated. In other words, the system stabilization bag r1155 is SRI
When the operation operation signal is on (7) The load of the BWR plant is above a certain value (for example, 20%), and the load when the power load unbalance relay 23 is activated is above a certain value (for example, 70%). When the conditions are met, a predetermined number of circuit breakers (breakers 58 to 62) connected to the load line 69 are connected to the load line 69 so that the system load reaches a certain value (for example, 20%) with a predetermined time delay (for example, 1.0 seconds). some) to limit the load.

FIG. 2 shows a load limiting interlock that is activated when a load shedding occurs, the power load unbalance relay 23 is not activated, and the intercept valve 48 is suddenly closed. The system stabilization device 55 receives an intercept valve sudden closing signal and when the load of the BWR plant in question when a load shedding occurs exceeds a certain value (for example, 60%) and the SRI does not operate. , some time delay (e.g. 1
．． 5 seconds), the circuit breakers 58 to 6 are activated as in the case of Fig. 1.
2, the system load can be reduced to a certain predetermined value (
For example, 20%).

In Figures 1 and 2, the initial load is the ratio of the load connected to the generator of the BWR plant to the total load before load shedding, and the residual load is the ratio of the load connected to the generator of the BWR plant to the total load after load shedding. It is a percentage of the total load. The system stabilizing device 55 includes a current transformer 7 provided in each load line 69.
The initial load and remaining load are calculated by inputting the outputs from 5 to 79.

Next, an outline of the BWR plants 56 and 57 shown in FIG. 3 will be explained with reference to FIGS. 4 and 5. Steam generated in the reactor pressure vessel 4o, which is a steam generator, is sent to a high-pressure turbine 41 through a main steam pipe 45, and further guided to a low-pressure turbine 42 through a cross-around pipe 47. Steam exhausted from the low pressure turbine 42 is condensed into water in a condenser 43. This condensed water is returned to the reactor pressure vessel 1 through a water supply pipe (not shown). Main steam pipe 45
A steam control valve 46 is provided at the cross-around pipe 47, and an intercept valve 48 is provided at the cross-around pipe 47. A bypass pipe 49 branched from the main steamer 45 on the upstream side of the steam control valve 46 is connected to the condenser 43 . A turbine bypass valve 50 is provided in bypass piping 49.

The rotating shaft of the high-pressure turbine 41 and the rotating shaft of the low-pressure turbine 42 are connected. Further, a generator 44 is detachably connected to the rotating shaft of the low-pressure turbine 42 . Pressure gauge 5
1.52, the output signals of the turbine speed detector 53 and ammeter 54 are input to the turbine control device 13.

The detailed configuration of the turbine control device 13 is shown in FIG. 5, and the operation of the turbine control device 113 will be described in detail below. Pressure gauges 51 and '52 are installed in the main steam pipe 45 and the cross-around pipe, respectively. The pressure gauge 51 may be attached to the reactor pressure vessel 1, 53 is a turbine speed detector that detects the rotational speed of the turbine, and 54 is an ammeter.

13 is a turbine control device, and a pressure gauge 51 measures the steam pressure discharged from the reactor pressure vessel 40.

An adder 55 calculates the deviation between the pressure signal 1 measured by the pressure gauge 51 and a preset pressure value 2. This deviation signal is input to the pressure regulator 4 via the filter circuit 3. The pressure regulator 4 creates a nationwide steam flow rate signal 5 based on the deviation signal. On the other hand, an adder 56 calculates the deviation between the turbine speed signal 8 measured by the turbine speed detector 53 and the turbine speed setting value 9.

The obtained deviation signal 1o is input to the speed regulator 11. The speed regulator 11 outputs a turbine speed control signal 12 according to the input deviation signal. The speed control signal 12 is
A load setting value 14, which is an output signal of the load setting device 15, is added by an adder 57 to form a speed/load control signal 13.

The total main steam flow signal 5 and the speed/load control signal 13 are input to a low value priority circuit 26. The low value priority circuit 26 selects the low value among these 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 an intermediate steam pressure signal 24 which is the output of the pressure gauge 52 and a generator current signal 25 which is the output of the ammeter 54, and when the difference between these signals exceeds a predetermined value, An actuation signal 22 is output. The pressure gauge 52 measures the steam pressure within the cross-around pipe 47 and outputs this measured value as an intermediate steam pressure signal 24. Ammeter 54 measures the current generated by generator 44 and outputs this measurement value as generator current signal 25.

The aforementioned actuation signal 22 is transmitted to the load setter 15. The signal is inputted to the instantaneous operation time limit recovery circuit 28 and the rate-of-change limit switch 34, respectively.

The opening degree of the turbine bypass valve 501 is controlled based on the bypass valve flow rate request signal '7 outputted 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 whole country 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 rate of change limiter 32, and the function of this rate of change limiter 32 will be described later.

In a BWR plant, the reactor output is adjusted by the amount of voids (steam bubbles) in the reactor core, so the neutron flux responds sensitively to pressure changes. Therefore, during normal operation, the steam control valve 46 is preferentially controlled by the nationwide steam flow rate signal 5 based on the pressure signal 1. In order to prevent the steam control valve 46 from operating in response to relatively small fluctuations in turbine speed, the load setting value 14 of the load setting device 15 is set to 10% of the total main steam flow rate signal.
It is set to be high. Therefore, the speed control signal 12 is within 10% (generally, the speed adjustment rate is 100% control signal 15% speed change, and in the case of 50Hz, 0.2
51 (corresponding to z), the steam control valve 46 does not respond to the turbine speed increase.
It is controlled by the nationwide steam flow rate signal 5, and pressure control is performed preferentially. - side, speed/load control signal 13 is 10%
Turbine speed increases such that it decreases by more than 0.25
For frequency increases above Hz), the speed/load control signal 13 will be smaller than the total main steam flow signal 5.

Therefore, the steam control valve 46 is controlled by the speed/load control signal 13 and throttled.

The surplus steam resulting from the throttling operation of the steam control valve 46 is directly exhausted to the condenser 43 by opening the turbine bypass valve 50 in response to the bypass valve flow rate request signal 7. In this way, by cooperatively operating the steam control valve 46 and the turbine bypass valve 50, the BWR plant operation can be stably continued without substantially changing the reactor pressure.

Further, the opening degree control of the intercept valve 48 that controls the flow rate of steam guided from the high pressure turbine 41 to the low pressure turbine 42 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 receives a control signal 18 corresponding to the deviation signal 10.
Output. Adder 59 receives control signal 18 . A control signal 19 obtained by multiplying the load setting value 14 by an intercept valve adjustment gain 16 and an intercept valve opening bias signal 2o are added, and an 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 100%.
, and the control signal multiplied by the adjustment gain 16 is set to be a large positive value, so the intercept valve 48 is always fully open, and the steam flow rate sent to the turbine is It is controlled by a steam control valve 46.

Next, the instantaneous operation time-limited return circuit 28 . which constitutes the turbine control device 13 . The speed/load signal switching circuit 29 and speed load limiter 30 will be explained. The instantaneous operation time limit recovery circuit 28 instantly adjusts the speed/speed by the activation signal 28 output when the power load unbalance relay 23 is activated.
The load signal switching circuit 29 is switched, and when the power load unbalance relay 23 is reset and the operating signal 28 is no longer output, the speed/load signal switching circuit 29 is switched to the original state after a predetermined time. The speed/load limiter 30 sets the 0% setting value as the speed/load setting signal 31 when the speed/load signal switching circuit 29 is switched by the activation signal 22 (when the power load unbalance relay 23 is activated). It outputs to the low value priority circuit 26, and when the speed/load signal switching circuit 29 is switched to its original state (when a predetermined period of time has elapsed after the power load imbalance relay 23 was reset), the set value of 110% is set. It is output to the low value priority circuit 26 as a speed/load setting signal 31.

The rate of change limiter switching circuit 34 controls the output signal of the rate of change limiter 32 to which the steam control valve flow rate request signal 27 is input. That is, the rate of change limiter switching circuit 34 is
If the operation signal 22 or the turbine trip generation signal 35 is not input, the steam control valve flow rate request signal 27. The change rate limiter 32 outputs the steam control valve flow rate subtraction signal 33 that limits the rate of change of the steam control valve flow rate. The rate-of-change limiter 32 is controlled so that the rate-of-change limiter 32 outputs the steam control valve flow rate subtraction signal 33 without any change. During normal operation of the BWR plant, the rate of change limiter 32:
The rate of change limit function mentioned above is always working.

The specific operation of this embodiment configured as described above will be explained.

First, if the power load unbalance relay 23 does not operate and a load shedding occurs to the extent that the intercept valve 48 suddenly closes, that is, the load shedding amount is 20% to 40%.
A description will be given of the BWR plant response when a load shedding of approximately 50% occurs. In such a load shedding, the rate of change limiter 32 outputs a steam control valve flow rate subtraction signal 33 to which the rate of change is limited. here,
Since the power load unbalance relay 23 does not operate, the set value 110 of 110% is output from the speed/load limiter 30.
A speed/load setting signal 31 set to % is output.

Further, since the rate-of-change limit switch 34 does not operate because there is no input signal, the rate-of-change limit WII 32 continues to output the steam control valve flow rate subtraction signal 33 that limits the rate of change.

Figure 6 shows the BWR plant response at this time.

The increase in turbine speed due to load shedding causes the speed/load control signal 12 to decrease, causing the speed/load control signal 12 to be below the total main steam flow signal 5. From this point on, steam control valve 4
6 is controlled and throttled by the speed/load control signal 12 selected by the low value priority circuit 26. Although there is a considerable difference between the actual opening/closing speed of the steam regulating valve 46 and the opening/closing speed of the turbine bypass valve 50, the change rate limiter 32 changes the steam regulating valve flow rate request signal 27 subtracted from the total main steam flow rate signal 5. Since the rate is limited, the turbine bypass valve 50 does not close suddenly, and the mismatch between the steam control valve flow rate and the turbine bypass valve flow rate is reduced (Fig. 6 (A)).
, fluctuations in the main steam flow rate and neutron flux become smaller (Fig. 6 (C)). Therefore, unnecessary main steam bulkhead valve closing scrams and high neutron flux scrams due to large main steam flow rates can be avoided. can.

In addition, after a holding time of 1.5 seconds, an interlock (Figure 2) that limits the system load to 20% is activated by the intercept valve quick-closing signal. A trip can be avoided (if the load is immediately limited by the intercept valve sudden closing signal, the turbine speed will increase at some point, potentially leading to a turbine trip).

When the power load unbalance relay 23 is activated, the quick-acting electromagnetic valve is energized to rapidly reduce the oil pressure of the steam regulating valve 46, thereby rapidly closing the steam regulating valve 46. At the same time, the load setting value 14 of the load setting device 15 becomes zero due to the actuation signal 22, and the speed/load control signal 13 becomes negative (zero in terms of control).
passes through the low value priority circuit 26.

Further, the operating signal 22 output from the power load unbalance relay 23 causes the rate of change limiter switch 34 to operate, and the rate of change limiter 32 stops the function of limiting the rate of change. Therefore, the speed/load control signal (zero) 1 which is the steam control valve flow rate request signal 27 output from the low value priority circuit 26
3 is input to the adder 58 as is. The turbine bypass valve 50 is suddenly opened by the bypass valve flow control signal 7 (bypass valve full open signal) obtained by correcting the whole country steam flow rate signal 5 with the unchanged value of the speed/load control signal 13 (valve opening degree and control (because the deviation from the signal is 5% or more).

After that, the turbine speed decreases to below the set value 9 due to the reduction in reactor output due to selective control insertion and the like and the influence of the operation of other plants. Here, if the turbine speed falls below set point 9 before power load unbalance relay 23 is reset, speed/load control signal 13 goes from positive to negative. On the other hand, the total main steam flow rate signal 5 has a maximum value of 110% due to a pressure increase due to a mismatch in the main steam flow rate due to the difference in valve characteristics between the sudden closing of the steam control valve and the sudden opening of the turbine bypass valve. Therefore, in the conventional device, the speed/load control signal 13 directly becomes the steam regulator flow rate control signal 27 to control the steam regulator in the direction of opening and the turbine bypass valve in the direction of closing. Therefore, only the turbine bypass valve 50 is throttled, and there is a possibility that a high pressure scram occurs. However, according to this embodiment, the power load unbalance relay.

The activation signal 22 of 23 activates the instantaneous operation time limit recovery circuit 28, and the switching circuit 29 activates the speed/load limiter 30.
The speed load setting signal 31 output from the motor becomes zero. For this reason, the instantaneous operation time limit return circuit 28 outputs the speed load setting signal 31 of the speed/load limiter 30 during the period until one second after the power load unbalance relay 23 is reset and the steam control valve quick closing reset is started. is held at zero, the steam control valve flow rate request signal 27 is also held at zero, and only the turbine bypass valve 50 is throttled, preventing a high pressure scram.

In addition, by resetting the power load unbalance relay 23, the rate of change limiter 32 operates again and starts the limiting operation, so the closing operation of the steam control valve 46 and the turbine bypass valve after resetting the power load unbalance relay 23 are performed. The difference between the closing operations of the valves 50 and 50 is reduced, and high pressure scrams and low water level scrams due to mismatch between the two are avoided.

Furthermore, the power load unbalance relay is activated.
After a hold time of 1.0 seconds, activation of an interlock (FIG. 1) that limits the system load to 20% avoids the aforementioned survey-like, low-frequency trips and turbine trips.

As described above, according to this embodiment, even if any load shedding occurs due to system disturbance, the atomic coupler can continue to operate stably while avoiding unnecessary scrams.

That is, according to this embodiment, when a turbine speed fluctuation occurs due to a system disturbance such as activation of a puff-load unbalance relay or a system disturbance other than a turbine trip, and the steam control valve and the turbine bypass valve open/close, the opening/closing speed changes. Since the rate of change of the steam regulator flow rate control signal is limited in accordance with the slow steam regulator valve, the deviation between the sum of the turbine bypass valve flow rate and the steam regulator flow rate and the total steam flow rate request signal is reduced, and therefore the reactor pressure Fluctuations can be suppressed and unnecessary scrums can be avoided.

Further, even if a load shedding such as activation of the power load unbalance relay 23 occurs, unnecessary scrams can be avoided by the speed/load limiting function, rate of change limit switching function, and system load limiting.

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

(Effects of the Invention) As described above, the present invention enables
By limiting the load within a predetermined capacity, the nuclear reactor plant can be operated stably and continuously, which has the effect of significantly improving the system disturbance resistance of the steam generation plant and increasing the operating rate.

[Brief explanation of the drawing]

1 and 2 are incorporated into the system stabilizing device shown in FIG. 3. An interlock diagram at the time of load restriction, FIG. 3 is a configuration diagram of an output control device of a steam generation plant that is an embodiment of the present invention, FIG. 4 is a configuration diagram of the BWR plant of FIG. 3,
Figure 5 is a detailed configuration diagram of the turbine control device in Figure 4;
The figure shows the BW when a system disturbance occurs to the extent that the power load unbalance relay does not operate in the embodiment shown in Figure 1.
Figure 7 is a characteristic diagram showing the BWR plant response when the power load unbalance relay is activated in the embodiment shown in Figure 1. Figure 8 is a characteristic diagram showing the BWR plant response under the same conditions as Figure 6. The characteristic diagram of the turbine control device of a conventional BWR plant, Fig. 9, is under the same conditions as Fig. 7.
1 is a characteristic diagram of a conventional BWR plant turbine control device in FIG. 4...Pressure regulator, 11...Speed regulator, 13...
- Turbine control device, 15... Load setting device, 17...
・Intercept valve speed regulator, 23... Power load unbalance relay, 26... Low value priority circuit, 28
... Instantaneous operation time limit recovery circuit, 29... Speed/load signal switching circuit, 30... Speed load limiter, 32... Rate of change limiter, 34... Rate of change limiter switching circuit, 4o・
...Reactor pressure vessel, 41...High pressure turbine, 42.
...Low pressure turbine, 46...Steam control valve, 48...
Intercept valve, 5o...Turbine bypass valve, 5
1.52...Pressure gauge, 53...Turbine speed detector, 54...Ammeter, 55...System stabilizer. 55-・-discipline 1 other 4 Hi crab place 6q-, Tsui 2 edge 9, s7-ri palm child force ζ hiderant 7θ
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Claims (1)

[Scope of Claims] 1. A system installed in a plurality of power systems that supplies power generated by a generator connected to a turbine to which steam generated by heat generated in a nuclear reactor is supplied to a load. A plurality of circuit breakers, a plurality of load detection means provided in each of the power systems to detect a load amount, and a load amount before load shedding and after load shedding determined based on the outputs of these load detection means. An output control device for a nuclear reactor plant, comprising means for outputting an open signal to the circuit breaker to limit the system load to a predetermined value based on a load amount of the circuit breaker and a selected control rod actuation signal. 2. Limiting the rate of change of the regulator valve flow rate request signal to be subtracted from the total steam flow rate signal, and outputting the rate of change to the turbine bypass valve flow rate request signal calculation means as a regulator valve flow rate subtraction signal, and the turbine load is suddenly reduced. A claim that is provided with a load limiter that forcibly sets the regulator valve flow rate request signal, which is the output signal of the low value priority gate, to a certain predetermined value for a certain period of time after the relay is activated when the power load unbalance relay is activated. 2. The power control device for a nuclear reactor plant according to item 1. 3. The output control system for a nuclear reactor plant according to claim 1, further comprising a power load unbalance relay or a switching device that switches the rate of change limit at the time of a turbine trip and uses the current control circuit. 4. The output control system for a nuclear reactor plant according to claim 1, further comprising means for canceling the operation of the load limiter after a certain period of time has elapsed after the power load imbalance relay is reset. 5. A plurality of circuit breakers provided in a plurality of power systems that supply electric power obtained from a generator connected to a turbine to which steam generated by heat generated in a nuclear reactor is supplied to a load; A plurality of load detection means provided in each of the electric power systems to detect a load amount, a load amount before load shedding determined based on the output of these load detection means, and a low pressure from a high pressure turbine among the turbines. An output control device for a nuclear reactor plant, comprising means for outputting an open signal to the circuit breaker in order to limit the system load to a predetermined value based on sudden closing of an intersect valve that adjusts the amount of steam to the turbine. 6. If the power load imbalance relay is activated due to a load cutoff connected to a generator connected to a turbine to which steam generated by heat generated in the nuclear reactor is supplied, the power load imbalance relay is activated after the load cutoff. A first load amount connected to the generator is determined, and a second load amount connected to the generator is determined based on a second load amount connected to the generator, the first load amount and an operation signal of the selection control unit before load shedding. An output control method for a nuclear reactor plant that limits the amount of load applied to a nuclear reactor plant to a predetermined value.