JP2019148539A - Load following device and nuclear power plant having the same - Google Patents

Abstract

To provide a load following device which can follow abrupt load fluctuation and/or load fluctuation having different amount of fluctuation and can appropriately control the load fluctuation, and a nuclear power plant having the load following device.SOLUTION: A load following device 2 comprises: control rod operation monitoring device 14 controlling a position of a control rod 15; a reactor recirculation flow rate control device 12 controlling the amount of cooling water in the reactor; an electric hydraulic control device 11 controlling a an opening degree of turbine steam regulating valve 6 provided in main steam piping 5 which guides the steam generated in the reactor to the turbine 8a and an opening degree of a bypass valve 7 provided in bypass piping which branches from the main steam piping 5 and communicates with a condenser 9; and a plant output changing method switching unit 16 changing the plant output by a control method which uses either one of a control rod operating monitoring unit 14, a reactor recirculation flow rate control unit 12 and the electric hydraulic control device 11 based on a change and a rate of change of turbine speed and an operating state of the reactor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a load following device in a nuclear power plant, and more particularly to a load following device that appropriately changes the output of a nuclear power plant according to a load and a nuclear power plant having the same.

  Nuclear power plants in normal operation generate steam using the heat generated by nuclear fission in the nuclear reactor, and the steam is sent to the turbine via the main steam pipe and directly connected to the turbine by rotating the turbine. Electricity is generated by driving a generator. When changing the output of the generator, the flow rate of turbine steam, which is steam sent to the turbine, is changed. The turbine steam flow rate can be changed by controlling the nuclear fission reaction in the reactor to control the reactor output and changing the main steam generated by the reactor, and changing the bypass steam flow rate. There is one that adjusts the turbine steam flow. As a method of controlling the nuclear fission reaction in the nuclear reactor, a method of inserting and extracting control rods using a control rod operation monitoring device (hereinafter also referred to as method (a)), a recirculation flow rate control device Is used to adjust the recirculation flow rate which is the circulation amount of the cooling water in the reactor (hereinafter also referred to as method (b)). On the other hand, a method of changing the plant output by adjusting the bypass steam flow (hereinafter also referred to as method (c)) is a method of adjusting the opening degree of the turbine steam control valve and the turbine bypass valve by an electrohydraulic control device. Is used.

  For example, in Patent Document 1, when there is a request for reducing the load on the nuclear power plant, the output of the nuclear power plant is reduced by the recirculation flow rate control device (the above method (b)), and then the control by the control rod drive control device. Control of rod drive (above method (a)) and control of the control valve and / or bypass valve by the main turbine controller for controlling the amount of steam generated from the reactor to the main turbine (above method (c)) ) To reduce the output of the nuclear power plant.

JP2015-222230A

The method (a) can change the output of the nuclear power plant at a low speed and the method (b) can change the output of the nuclear power plant at a medium speed with a medium amount of change. c) is characterized in that the output of a small nuclear power plant can be changed rapidly. However, in the configuration described in Patent Document 1, no consideration is given to a change in the combination of these methods (a) to (c). That is, it is always fixed to the control rod insertion / extraction (method (a)) and the bypass valve opening method (method (c)) after the recirculation flow rate control (method (b)). There is a concern that appropriate control cannot be executed with respect to various load fluctuations and / or load fluctuations having various amounts of change.
Therefore, the present invention provides a load following device capable of following and controlling appropriately a sudden load fluctuation and / or a load fluctuation having various changes, and a nuclear power plant having the same.

In order to solve the above problems, a load follower according to the present invention includes a control rod operation monitoring device that controls the position of a control rod, a recirculation flow rate control device that controls the circulation amount of cooling water in a nuclear reactor, Electricity for controlling the opening degree of the turbine steam control valve provided in the main steam pipe for guiding the steam generated in the furnace to the turbine and the bypass valve provided in the bypass pipe branched from the main steam pipe and communicating with the condenser At least one of the control rod operation monitoring device, the recirculation flow rate control device, and the electrohydraulic control device based on the hydraulic control device, the amount and rate of change in turbine speed, and the operating state of the reactor And a plant output changing method switching device for changing the plant output by a control method using the above.
The nuclear power plant according to the present invention includes a nuclear reactor, a turbine steam control valve provided in a main steam pipe for guiding steam generated in the nuclear reactor to a turbine, and a condenser branched from the main steam pipe. A control valve operation monitoring device for controlling the position of the control rod and recirculation for controlling the circulation amount of the cooling water in the nuclear reactor. A flow control device, an electrohydraulic control device for controlling the opening degree of the turbine steam control valve and the bypass valve, and the control rod operation monitoring device based on the amount and rate of change of the turbine speed and the operating state of the reactor And a plant output change method switching device for changing a plant output by a control method using at least one of the recirculation flow rate control device and the electrohydraulic control device, Characterized in that it comprises a load following device for.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the load follower which can track and control appropriately according to the rapid load fluctuation and / or the load fluctuation which has various change amount, and a nuclear power plant having the same.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an overall schematic configuration diagram of a nuclear power plant having a load following device according to an embodiment of the present invention. It is a block diagram which shows the function of the plant output change system switching apparatus shown in FIG.

As the nuclear reactor constituting the nuclear power plant according to the embodiment of the present invention, for example, a recirculation pump is provided and cooling water as a moderator is passed outside the reactor pressure vessel and again flows into the downcomer inside the reactor pressure vessel. In general, a boiling water reactor (BWR) that circulates cooling water or an improved boiling water reactor (ABWR) having an internal pump is used. As an example, the case of an improved boiling water reactor (ABWR) will be described.
Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an overall schematic configuration diagram of a nuclear power plant having a load follower according to an embodiment of the present invention. In FIG. 1, signal lines are indicated by dotted arrows. As shown in FIG. 1, during normal operation of the nuclear power plant 1, the cooling water pressurized in the core 4 in the reactor pressure vessel (reactor) 3 becomes steam due to heat generated by the fission reaction. The steam is attached to a shroud head (not shown) that covers the core 4 and the moisture is removed by a steam / water separator (not shown) that extends upward and a steam dryer (not shown) disposed above the steam / water separator. After being removed, it is sent to the turbine 8 a via the main steam pipe 5. The steam flow rate after the moisture flowing into the turbine 8a is removed via the main steam pipe 5 is adjusted by adjusting the opening degree of the turbine steam control valve 6 installed near the inlet of the turbine 8a. A turbine 8 a is connected to a generator 8 b to constitute the turbine generator 8.

  Cooling water that flows into the reactor pressure vessel 3 from the water supply pipe 10 through the condenser 9 that condenses the steam exhausted from the turbine 8a flows (falls) downward in the downcomer (not shown). . A plurality of internal pumps 13 are installed in the lower mirror, which is the bottom of the reactor pressure vessel 3, so as to penetrate the reactor pressure vessel 3 from below. The plurality of internal pumps 13 are outside the outermost peripheral portions of the plurality of control rod guide pipes, and are annularly spaced apart from each other at a predetermined interval. Thereby, the internal pump 13 does not interfere with the control rod guide tube or the like. The impeller of each internal pump 13 is positioned in an annular downcomer (not shown) formed between the cylindrical core shroud and the inner surface of the reactor pressure vessel 3. The internal pump 13 forcibly circulates cooling water to the core 4 in order to control heat generated in the core 4.

  The load follower 2 according to the present embodiment includes an electrohydraulic control device 11, a reactor recirculation flow control device 12 (sometimes referred to as a recirculation flow control device), a control rod operation monitoring device 14 (control rod). And a plant output change system switching device 16.

  The electrohydraulic control device 11 adjusts the opening degree of the turbine steam control valve 6 so as to keep the reactor pressure constant, and the opening degree of the turbine steam control valve 4 according to the turbine speed signal. The turbine speed control unit is configured to adjust and control the turbine speed to be kept constant. In the case of a nuclear power plant having an improved boiling water reactor (ABWR), pressure control is prioritized during normal operation unless the turbine speed increases significantly, and the opening of the bypass valve 7 is adjusted during turbine speed control. The reactor pressure is controlled to be constant. As shown in FIG. 1, the bypass valve 7 is installed in a bypass pipe that is the main steam pipe 5 and branches upstream from the turbine steam control valve 6 and communicates with the condenser 9. In addition, a pressure gauge PT is installed upstream of the branch portion of the bypass pipe where the bypass valve 7 is installed, and the turbine inlet pressure measured by the pressure gauge PT is controlled by electrohydraulic control. Input to the device 11.

  The reactor recirculation flow rate control device 12 recirculates the cooling water in the reactor pressure vessel 3 (reactor) for the purpose of controlling fission reaction by the void amount of the cooling water in the reactor pressure vessel 3 (reactor). Control recirculation pump speed to regulate flow rate. Specifically, the speed command value is output to the internal pump 13 described above. The reactor recirculation flow control device 12 adjusts the speed of the internal pump 13 in accordance with the recirculation flow request value calculated based on the reactor output command signal and the actual output signal from the electrohydraulic control device 11.

  The control rod operation monitoring device 14 is a device that controls the position of the control rod 15 by automatic operation or manual operation by an operator. There are two types of insertion of the control rod 15: normal insertion operation used in normal operation and emergency control rod insertion operation used in an emergency. The former is used for adjusting the reactor power during normal operation. On the other hand, the latter is used as an emergency insertion function by electric drive as a backup of control rod insertion operation by hydraulic drive such as scram.

  In the load following device 2 according to the present embodiment, the plant output change method switching device 16 selects the plant output change method according to the turbine speed change and the operation state of the reactor, and the electrohydraulic control device 11 Commands are output to the circulation flow control device 12 and the control rod operation monitoring device 14. Hereinafter, details of the plant output change system switching device 16 will be described.

<Configuration of plant output change method switching device 16>
FIG. 2 is a block diagram showing functions of the plant output changing system switching device 16 shown in FIG. As shown in FIG. 2, the plant output change method switching device 16 includes a plant output change amount calculation unit 21, an output change enable / disable determination unit 23 based on a recirculation flow rate, a changeover switch 24, a first combination selection unit 28, and a second. The combination selection unit 29 is configured. The plant output change amount calculation unit 21, the output change possibility determination unit 23 based on the recirculation flow rate, the first combination selection unit 28, and the second combination selection unit 29 include, for example, a processor such as a CPU (not shown) and various programs. Is realized by a storage device such as a ROM for temporarily storing calculation process data, a RAM for temporarily storing calculation process data, an external storage device, and the like, and a processor such as a CPU reads out and executes various programs stored in the ROM. Is stored in a RAM or an external storage device. The changeover switch 24 may be either a software switch or a hardware switch.

  The plant output change amount calculation unit 21 receives the turbine speed change amount signal detected from the turbine generator 8 and calculates the plant output change amount based on the turbine speed change amount signal. Here, the plant output means the output of the nuclear power plant 1, and is naturally equivalent to the output of the generator 8b constituting the nuclear power plant 1. The plant output change amount calculation unit 21 stores the relationship between the frequency and the output in advance in a storage unit (not shown), calculates the plant output change amount from the input turbine speed change amount signal, and the plant output change amount signal 22. Is output to the output change possibility determination unit 23 and the changeover switch 24 based on the recirculation flow rate. Here, since the frequency of the system and the turbine speed are basically equal, the amount of change in the plant output corresponding to the turbine speed change amount signal from the predetermined speed adjustment rate based on the relationship between the frequency and the output stored in advance. Is calculated.

  The output change possibility determination unit 23 based on the recirculation flow rate inputs the plant output change amount signal 22 from the plant output change amount calculation unit 21 and the reactor output and the recirculation flow rate that are the current operation state of the nuclear power plant 1. . The output change possibility determination unit 23 based on the recirculation flow rate stores in advance a PF map, that is, a map indicating a plant operable region in which the recirculation flow rate is plotted on the horizontal axis and the reactor output is plotted on the vertical axis in a storage unit (not shown). Yes. The output change possibility determination unit 23 based on the recirculation flow rate compares the plant output change amount signal 22 with the current operation state of the nuclear power plant 1 composed of the reactor output and the recirculation flow rate, and recirculation flow rate based on the PF map. It is determined whether or not the reactor power can be changed by adjusting the power. In other words, it is determined whether or not the reactor power can be changed by the method (b).

  The changeover switch 24 uses a signal (discrimination result) from the output change possibility determination unit 23 based on the recirculation flow rate to convert the plant output change amount signal 22 input from the plant output change amount calculation unit 21 into a first combination described later. Connected to either channel (when method (b) is not used) 25 that can be output to selection unit 28 or channel 26 (when method (b) is used) that can be output to second combination selection unit 29 It is configured to

  The first combination selection unit 28 is a graph that allows a storage unit (not shown) to select a combination of output change methods in which the horizontal axis is the turbine speed change rate and the output change amount (plant output change amount) is the vertical axis. Is stored. For example, as shown in FIG. 2, when the turbine speed change rate is low and the output change amount (plant output change amount) is small, a method of changing the plant output by adjusting the bypass steam flow rate (method (c)) is selected. Is done. When the turbine speed change rate is medium and the output change amount (plant output change amount) is medium, a method of changing the plant output by adjusting the bypass steam flow rate (method (c)) and a control rod operation monitoring device 14 is used to select a combination of methods (method (a)) in which the control rod 15 is inserted and pulled out. Further, when the turbine speed change rate is high and the output change amount (plant output change amount) is large, a method of changing the plant output by adjusting the bypass steam flow rate (method (c)) and the control rod operation monitoring device 14 are used. Thus, a combination of methods (method (a)) for inserting and extracting the control rod 15 is selected.

  The second combination selection unit 29 is a graph that enables a storage unit (not shown) to select a combination of output change methods in which the turbine speed change rate is plotted on the horizontal axis and the output change amount (plant output change amount) is plotted on the vertical axis. Is stored. For example, as shown in FIG. 2, when the turbine speed change rate is low and the output change amount (plant output change amount) is small, a method (method (b)) for adjusting the recirculation flow rate is selected. When the turbine speed change rate is medium and the output change amount (plant output change amount) is large, the control rod 15 is adjusted using the method (method (b)) for adjusting the recirculation flow rate and the control rod operation monitoring device 14. A combination of methods (method (a)) for inserting and pulling out is selected. Further, when the turbine speed change rate is high and the output change amount (plant output change amount) is medium, the method of changing the plant output by adjusting the bypass steam flow rate (method (c)) and the recirculation flow rate are adjusted. A combination of methods (method (b)) is selected.

<Operation of Plant Output Change Method Switching Device 16>
When a change occurs in the turbine speed detected by the turbine generator 8, the change signal of the turbine speed is input to the plant output change calculation unit 21. The plant output change amount calculation unit 21 calculates the change amount of the plant output according to the turbine speed change amount as described above, and the output change permission determination unit 23 and the changeover switch 24 based on the recirculation flow rate as the plant output change amount signal 22. Output to.

  The output change possibility determination unit 23 based on the recirculation flow rate specifies the current operating point on the PF map from the detected reactor output and the recirculation flow rate and the plant output change signal 22 when input, and the recirculation flow rate. It is determined whether or not the output can be changed using, and the result is output to the changeover switch 24. The changeover switch 24 switches to a channel 25 (when the system (b) is not used) 25 when the output change based on the recirculation flow rate is impossible based on the result of the output change possibility determination unit 23 based on the recirculation flow rate. (When method (b) is used) 26 is connected to output the plant output change amount signal 22.

When the plant output change amount signal 22 that is an output signal from the plant output change amount calculation unit 21 is connected to the channel 25 in the changeover switch 24, the first combination selection unit 28, as described above, changes the turbine speed change. Based on the rate signal 27 and the plant output change amount signal 22, a predetermined combination of plant output change methods is selected. Then, the first combination selection unit 28 outputs a control command to the control rod operation monitoring device 14 and / or the electrohydraulic control device 11 based on the selected combination. For example, as described above, when the turbine speed change rate is high and the output change amount (plant output change amount) is large, a method of changing the plant output by adjusting the bypass steam flow rate (method (c)) and control rod operation A combination of methods (method (a)) for inserting and withdrawing the control rod 15 using the monitoring device 14 is selected, and a control command is output to the control rod operation monitoring device 14 and the electrohydraulic control device 11.
On the other hand, when the plant output change amount signal 22 is connected to the channel 26 in the changeover switch 24, the second combination selection unit 29, as described above, uses the turbine speed change rate signal 27 and the plant output change amount signal 22 as described above. A combination of plant output change methods determined in advance is selected. The second combination selection unit 29 then selects one or a combination of the control rod operation monitoring device 14, the reactor recirculation flow rate control device 12, and the electrohydraulic control device 11 based on the selected combination. A control command is output to For example, as described above, when the turbine speed change rate is low and the output change amount (plant output change amount) is small, a method of adjusting the recirculation flow rate (method (b)) is selected, and the reactor recirculation flow rate is selected. A control command is output to the control device 12. Further, when the turbine speed change rate is high and the output change amount (plant output change amount) is medium, the method of changing the plant output by adjusting the bypass steam flow rate (method (c)) and the recirculation flow rate are adjusted. A combination of methods (method (b)) is selected, and control commands are output to the reactor recirculation flow rate control device 12 and the electrohydraulic control device 11, respectively.

As described above, according to the present embodiment, it is possible to provide a load follower that can appropriately control by following a sudden load change and / or a load change having various changes, and a nuclear power plant having the load follower. It becomes possible.
In addition, by realizing the function to select or combine plant output change methods according to the amount and rate of change in turbine speed, it is always possible to use an optimum output change method according to the fluctuation pattern of the turbine speed and the operating state of the nuclear power plant. Load following can be performed.
In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

DESCRIPTION OF SYMBOLS 1 ... Nuclear power plant 2 ... Load follower 3 ... Reactor pressure vessel 4 ... Core 5 ... Main steam piping 6 ... Turbine steam control valve 7 ... Bypass valve 8 ... Turbine generator 8a ... Turbine 8b ... Generator 9 ... Condensate Equipment 10 ... Feed water piping 11 ... Electrohydraulic control device 12 ... Reactor recirculation flow rate control device 13 ... Internal pump 14 ... Control rod operation monitoring device 15 ... Control rod 16 ... Plant output change method switching device 21 ... Plant output change Quantity calculation unit 22 ... Plant output change amount signal 23 ... Output change possibility determination unit 24 by recirculation flow rate ... Changeover switch 25 ... Channel (when system (b) is not used)
26 ... Channel (when using method (b))
27 ... Turbine speed change rate signal 28 ... 1st combination selection part 29 ... 2nd combination selection part

Claims (8)

  The control rod operation monitoring device that controls the position of the control rod, the recirculation flow rate control device that controls the circulation amount of the cooling water in the reactor, and the main steam pipe that guides the steam generated in the reactor to the turbine An electrohydraulic control device for controlling the opening degree of the bypass valve provided in the bypass pipe provided from the turbine steam control valve and the bypass pipe branched from the main steam pipe and connected to the condenser; Plant output change method switching for changing plant output by a control method using at least one of the control rod operation monitoring device, the recirculation flow rate control device, and the electrohydraulic control device based on the operating state of the reactor And a load following device. The load follower according to claim 1,
The load follower characterized in that the operating state of the nuclear reactor is an output and a recirculation flow rate of the nuclear reactor. In the load follower according to claim 1 or 2,
The plant output change system switching device is
A first combination selection unit for selecting a control method using the control rod operation monitoring device and / or the electrohydraulic control device;
And a second combination selection unit that selects a control method using any one or two of the control rod operation monitoring device, the recirculation flow rate control device, and the electrohydraulic control device. A load following device. In the load follower according to claim 3,
The plant output change system switching device is
A load follower having a switching unit that switches to the first combination selection unit or the second combination selection unit based on a change amount and a change rate of the turbine speed and an operating state of the reactor. A reactor, a turbine steam control valve provided in a main steam pipe for guiding steam generated in the reactor to a turbine, and a bypass valve provided in a bypass pipe branched from the main steam pipe and communicating with a condenser A nuclear power plant having
Control rod operation monitoring device for controlling the position of the control rod, recirculation flow rate control device for controlling the circulation amount of cooling water in the reactor, and electrohydraulic pressure for controlling the opening degree of the turbine steam control valve and the bypass valve And at least one of the control rod operation monitoring device, the recirculation flow rate control device, and the electrohydraulic control device based on the amount and rate of change in turbine speed and the operating state of the reactor. A nuclear power plant comprising: a load follower having a plant output changing method switching device for changing a plant output by a control method used. In the nuclear power plant according to claim 5,
The nuclear power plant, wherein the operating state of the nuclear reactor is an output of the nuclear reactor and a recirculation flow rate. In the nuclear power plant according to claim 5 or 6,
The plant output change system switching device is
A first combination selection unit for selecting a control method using the control rod operation monitoring device and / or the electrohydraulic control device;
And a second combination selection unit that selects a control method using any one or two of the control rod operation monitoring device, the recirculation flow rate control device, and the electrohydraulic control device. A nuclear power plant. The nuclear power plant according to claim 7,
The plant output change system switching device is
A nuclear power plant comprising: a switching unit that switches to the first combination selection unit or the second combination selection unit based on a change amount and a change rate of the turbine speed and an operating state of the reactor.

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