CN116469593A - A main water supply system of a nuclear power plant and a control method for the main water supply system - Google Patents

Abstract

The invention relates to a main water supply system of a nuclear power plant and a control method of the main water supply system. Comprising the following steps: a plurality of main feed passages, a standby passage, a feed water heating device, a main feed water adjusting device, a steam generating device, a steam turbine and a control device; the main supply passage and the standby passage are used for supplying water to the steam generating device; the steam generating device is used for providing working steam for the steam turbine; the control device is used for executing the following processes: monitoring the working state of the main feed passage, triggering the standby passage to start when any main feed passage is turned off, and triggering the main feed water regulating device to be in a maximum flow state; monitoring the working state of the standby passage, judging whether the standby passage enters a normal working state after delaying for a preset time, if so, maintaining the current working state of the steam turbine, and triggering the main water supply adjusting device to be in a default flow state; if not, the working load of the steam turbine is reduced. By implementing the invention, the operation reliability of the nuclear power plant can be effectively ensured.

Description

A main water supply system of a nuclear power plant and a control method for the main water supply system

technical field

The invention relates to the technical field of nuclear power plant operation and safety, and more specifically relates to a main water supply system of a nuclear power plant and a control method for the main water supply system.

Background technique

In a certain type of pressurized water reactor nuclear power plant, the technical solution adopted for the main feedwater system is to set up three main feedwater pumps to operate, and the three main feedwater pumps draw water from the condensate tank and send it to two steam generators through the feedwater heater. The main feedwater flow into each steam generator is regulated and controlled by the main feedwater regulating valve of each water supply pipeline.

According to the operating experience of nuclear power plants, the main feed water pump has a relatively high failure rate. In a nuclear power plant adopting the technical scheme of three main feedwater pumps, if one main feedwater pump fails, the flow of main feedwater delivered to the steam generator will decrease; if the steam turbine maintains full-load operation (steam flow remains unchanged), the water level of the steam generator will decrease because the amount of steam extracted from the steam generator by the steam turbine is greater than the feedwater delivered to the steam generator by the main feedwater pump; the continuous decrease of the water level will trigger the "steam generator water level low" emergency shutdown signal of the reactor protection system. In order to avoid emergency shutdown of the reactor, the control logic of this type of nuclear power plant is set as follows: After detecting a main feed water pump shutdown signal, the control system automatically starts the steam turbine to reduce the load. The steam turbine will quickly deload to 70% of its rated value, and its steam extraction will be rebalanced with the water delivery of the remaining two main feed water pumps. The plant will remain operating at 70% capacity until the third main feedwater pump is repaired. This will reduce the availability of nuclear power plants, leading to economic losses.

Contents of the invention

The technical problem to be solved by the present invention is to provide a main water supply system of a nuclear power plant and a control method for the main water supply system.

The technical solution adopted by the present invention to solve the technical problem is to construct a main water supply system of a nuclear power plant, including: multiple main water supply passages, as well as backup passages, feedwater heating devices, main feedwater adjustment devices, steam generating devices, steam turbines and control devices;

the main supply path and the backup path are used to connect to a water supply device, and

The main supply passage and the standby passage are sequentially connected to the steam generating device via the feed water heating device and the main feed water regulating device, so as to supply water to the steam generating device;

The steam generating device is connected to the steam turbine for providing working steam for the steam turbine;

The control device is connected to the main water supply passage, the backup passage, the main feed water regulating device and the steam turbine, and is used to perform the following process:

monitoring the working state of the main water supply channel, triggering the standby channel to start when any of the main water supply channels is shut down, and triggering the main water supply regulating device to be in the maximum flow state;

monitoring the working state of the backup path, and judging whether the backup path has entered a normal working state after a preset time delay,

If so, maintain the current working state of the steam turbine, and trigger the main feed water regulating device to be in a default flow state;

If not, reduce the workload of the steam turbine.

Preferably, in the main water supply system of a nuclear power plant according to the present invention, the main water supply passage includes: a main feedwater pump, a first backflow regulating passage and a first non-return device;

The input end of the main feed water pump is used to connect to the water supply device, the output end of the main feed water pump is connected to the input end of the first backflow regulation passage and the input end of the first check device, the output end of the first back flow adjustment passage is connected to the water supply device, the output end of the first check device is connected to the input end of the feed water heating device, and the output end of the feed water heating device is connected to the input end of the main feed water adjustment device.

Preferably, in the main water supply system of a nuclear power plant according to the present invention, the backup passage includes: a backup feedwater pump, a second backflow regulating passage and a second non-return device;

The input end of the backup feed water pump is used to connect to the water supply device, the output end of the backup feed water pump is connected to the input end of the second backflow regulation passage and the input end of the second check device, the output end of the second back flow adjustment passage is connected to the water supply device, the output end of the second check device is connected to the input end of the feed water heating device, and the output end of the feed water heating device is connected to the input end of the main feed water adjustment device;

The control device is used for triggering the standby water feed pump to work so as to trigger the standby pathway to be turned on when any one of the main water supply pathways is shut off.

Preferably, in the main water supply system of a nuclear power plant according to the present invention, the backup path further includes an electric isolation device;

The input end of the electric isolating device is connected to the output end of the standby feed water pump, the output end of the electric isolating device is connected to the input end of the second non-return device, and the control end of the electric isolating device is connected to the control device;

The control device is used for triggering the conduction of the electric isolation device when any of the main supply channels is shut off, so as to trigger the conduction of the standby channel.

Preferably, in the main water supply system of a nuclear power plant according to the present invention, the control device is further configured to trigger and generate an alarm signal when more than one main water supply channel is shut off.

Preferably, in the main water supply system of a nuclear power plant according to the present invention, the control device is further used to acquire the reduction degree of the feed water flow when the feed water flow in the main water supply channel decreases, so as to control the flow state of the main feed water regulating device according to the reduction degree.

Preferably, in the main water supply system of the nuclear power plant according to the present invention, the nuclear power plant is a third-generation passive nuclear power plant, and the preset time is 30s.

Preferably, in the main water supply system of a nuclear power plant according to the present invention, the plurality of main water supply channels include three main water supply channels.

Preferably, in the main water supply system of a nuclear power plant according to the present invention, when the control device reduces the working load of the steam turbine, the working load of the steam turbine is reduced to 70% of the rated load of the steam turbine.

The present invention also constructs a method for controlling the main water supply system of a nuclear power plant, which is applied to the main water supply system of a nuclear power plant as described above; the control method includes:

Monitoring the working status of the main water supply passages in the main water supply system, triggering the standby passage in the main water supply system to start when any of the main water supply passages is shut off, and triggering the main water supply regulating device in the main water supply system to be in the maximum flow state;

monitoring the working state of the backup passage in the main water supply system, and judging whether the backup passage has entered a normal working state after delaying the preset time,

If so, maintain the current working state of the steam turbine in the main water supply system, and trigger the main water supply regulating device in the main water supply system to be in a default flow state;

If not, reduce the workload of the steam turbine.

The implementation of the main water supply system of a nuclear power plant and the control method for the main water supply system of the present invention has the following beneficial effects: the availability rate of the nuclear power plant can be effectively improved, and the operation reliability of the nuclear power plant can be ensured.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is a schematic structural view of an embodiment of the main water supply system of a nuclear power plant of the present invention;

Fig. 2 is a program flow chart of an embodiment of a method for controlling the main water supply system of a nuclear power plant according to the present invention.

Detailed ways

In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation manners of the present invention will now be described in detail with reference to the accompanying drawings.

As shown in Figure 1, in the first embodiment of the main water supply system of a kind of nuclear power plant of the present invention, comprise: a plurality of main supply channels 110, and backup channels 120, feed water heating device 130, main feed water regulating device 140, steam generating device 150, steam turbine 220 and control device (not shown in the figure); 130 is connected with the main feedwater regulating device 140 to the steam generating device 150 for supplying water to the steam generating device 150; the steam generating device 150 is connected to the steam turbine 220 to provide working steam for the steam turbine 220; When 110 is turned off, trigger the backup passage 120 to start, and trigger the main feedwater regulating device 140 to be in the maximum flow state; monitor the working state of the backup passage 120, and judge whether the backup passage 120 enters a normal working state after delaying the preset time, if so, maintain the current working state of the steam turbine 220, and trigger the main feedwater regulating device 140 to be in the default flow state; Specifically, in the main water supply system of a nuclear power plant, feedwater is extracted from the water supply device 210 by setting multiple main feedwater passages 110 and heated by the feedwater heater, and the main feedwater regulating device 140 is opened according to the flow demand to control the steam volume of the steam generating device 150 to match the workload of the steam turbine 220. And a backup path 120 is provided, wherein the working process of the backup path 120 is controlled by the control device. Wherein, when the main water supply system is working normally, the control device detects the working status of all the main water supply channels 110 to determine whether the main water supply channels 110 are shut off. Only when the main water supply channel 110 is abnormally shut down, the standby channel 120 is triggered to start, and at the same time, the main water supply regulating device 140 is triggered to be in the maximum flow state. At this time, the main water supply system enters a transient process of operation. By setting the main water supply regulating device 140, the water flow rate of the nuclear power plant is maintained at full load. The control device is the same as the working state of the backup path 120, and counts the duration of triggering the startup of the backup path 120, and judges whether the backup path 120 has entered a normal working state after delaying for a preset time. That is, the preset time is the time during which the steam turbine 220 can maintain normal operation. The backup channel 120 works normally before and including the preset time, which will not affect the working state of the steam turbine 220. At this time, the current working state of the steam turbine 220 can be maintained, that is, full-load operation. At the same time, when the backup channel 120 enters the normal working state, adjust the main water supply regulating device 140 to return to the default flow state, that is, it is not necessary to set the main water supply regulating device 140 to the maximum flow state at this time. If the backup channel 120 does not enter the normal working state after the preset time, it can be understood that the backup channel 120 failed to connect. At this time, the steam flow taken away by the steam turbine 220 under full load conditions will be higher than the feed water flow rate, and the water level of the steam generator will continue to decrease until the low water level signal of the steam generator is triggered, resulting in an emergency shutdown. Therefore, at this time, it is necessary to reduce the workload of the steam turbine 220 so that the steam turbine 220 can work without causing an emergency shutdown.

Optionally, the main feedwater passage 110 includes: a main feedwater pump 111, a first backflow regulating passage 112, and a first check device 113; the input end of the main feedwater pump 111 is used to connect to the water supply device 210, the output end of the main feedwater pump 111 is connected to the input end of the first backflow regulating passage 112 and the input end of the first check device 113, and the output end of the first backflow regulating passage 112 is connected to the water supply device 210, the first check device The output end of 113 is connected to the input end of the feedwater heating device 130 , and the output end of the feedwater heating device 130 is connected to the input end of the main feedwater regulating device 140 . Specifically, in the main water supply passage 110, the main feedwater pump 111 is used to draw water from the water supply device 210, and the first backflow adjustment passage 112 is used to adjust the water volume of the water from the main feedwater pump 111 entering the feedwater heater. The first check device 113 is used to prevent water backflow. In an embodiment, monitoring the working state of the main water supply passage 110 may be monitoring the working state of the main feedwater pump 111 , and when the speed of the main water supply pump 111 rapidly decreases to zero, it is judged that the main water supply passage 110 is shut down.

Optionally, the backup passage 120 includes: a backup feedwater pump 121, a second backflow regulating passage 122, and a second check device 123; the input end of the backup feedwater pump 121 is used to connect to the water supply device 210, the output end of the backup feedwater pump 121 is connected to the input end of the second backflow regulation passage 122 and the input end of the second check device 123, and the output end of the second backflow regulation passage 122 is connected to the water supply device 210, and the second check device 120 The output end of 23 is connected to the input end of the feed water heating device 130, and the output end of the feed water heating device 130 is connected to the input end of the main feed water regulating device 140; the control device is used to trigger the standby feed water pump 121 to work to trigger the backup channel 120 to be turned on when any of the main feed water channels 110 is shut off. Specifically, in the standby channel 120, water is pumped from the water supply device 210 through the standby feedwater pump 121, and the water volume of the standby feedwater pump 121 entering the feedwater heater is adjusted through the second backflow adjustment channel 122, and the second check device 123 is used to prevent water backflow. In one embodiment, triggering the standby passage 120 is triggering the standby water pump to start working. Wherein monitoring the working state of the backup channel 120 includes monitoring the starting status of the backup water pump. That is to confirm whether the speed of the standby water pump meets the normal requirements.

Optionally, the backup path 120 further includes an electric isolation device 124; the input end of the electric isolation device 124 is connected to the output end of the backup feed water pump 121, the output end of the electric isolation device 124 is connected to the input end of the second non-return device 123, and the control end of the electric isolation device 124 is connected to the control device; the control device is used to trigger the conduction of the electric isolation device 124 to trigger the conduction of the backup path 120 when any of the main supply paths 110 is shut off. Specifically, an electric isolation device 124 is also provided in the backup passage 120 to prevent the backup passage 120 from being opened when the backup water pump is activated by mistake, so as to improve the reliability of the control process. It can be understood that when the control device normally controls the startup of the backup water pump, it will also trigger the conduction of the electric isolation device 124 so that the backup passage 120 is activated, and any device that is activated by mistake will not cause the backup passage 120 to be connected. In one embodiment, the electric isolation device 124 includes an outlet isolation valve, and the backup channel 120 is controlled to be turned on or off by controlling the outlet isolation valve to be turned on or off.

Optionally, the control device is further configured to trigger and generate an alarm signal when more than one main feed path 110 is shut down. Specifically, when the control device judges that more than one main supply channel 110 is shut down, and the control device cannot control the working state of the water supply system to alleviate the fault, the low water level signal of the steam generator will directly trigger the emergency shutdown protection signal. At this time, an alarm is directly generated for failure alarm.

Optionally, the control device is further configured to acquire the reduction degree of the feedwater flow rate when the feedwater flow rate in the main feedwater passage 110 decreases, so as to control the flow state of the main feedwater regulating device 140 according to the decrease degree. Specifically, the control device is also used to measure the feedwater flow rate of the main feedwater channel 110 , and when the feedwater flow rate decreases, obtain the degree of reduction of the feedwater flow rate, and control the flow state of the main feedwater regulating device 140 according to the decrease degree. In one embodiment, the opening of the main feedwater regulating valve is usually set at about 80% for normal operation. If the performance of the main feedwater pump 111 in the main feedwater passage 110 decreases, the corresponding main feedwater regulating valve will increase the valve opening according to the control signal to increase the flow.

Optionally, the nuclear power plant is a third-generation passive nuclear power plant, and the preset time is 30s. Specifically, for the current mainstream third-generation passive nuclear power plants, the steam flow rate taken away by the steam turbine 220 under full load conditions will be higher than the feedwater flow rate, and the water level of the steam generator will continue to decrease until the low water level signal of the steam generator is triggered, resulting in an emergency shutdown time of more than 30s. Therefore, it can be set to determine whether the standby water pump has not entered the normal working state after 30s. It can be understood that the setting of the standby water pump and the outlet isolation valve can be completed within 30S, for example. In one embodiment, the time from start-up to full speed of the standby water pump is about 6 seconds, and the time to fully open the outlet isolation valve is set to 5 seconds. Both of these two times can meet the feedwater flow demand of the nuclear power plant to maintain full-load operation.

Optionally, the plurality of main water supply passages 110 include three main water supply passages. Based on the current third-generation passive nuclear power plant, the main water supply system is provided with three main channels for normal water supply.

Optionally, when the control device reduces the working load of the steam turbine 220, the working load of the steam turbine 220 is reduced to 70% of the rated load of the steam turbine 220. Specifically, when the control device reduces the workload of the steam turbine 220 because the standby channel 120 cannot enter the normal working state, the workload of the steam turbine 220 is reduced to 70% of the rated load of the steam turbine 220, so as to maintain the normal operation of the nuclear power plant.

In addition, as shown in FIG. 2 , in a method for controlling the main water supply system of a nuclear power plant according to the present invention, it is applied to the main water supply system of a nuclear power plant as described in any one of the above; the control method includes: S1, monitoring the working status of the main water supply passage 110 in the main water supply system, when any of the main water supply passages 110 is shut off, triggering the backup passage 120 in the main water supply system to start, and triggering the main water supply regulating device 140 in the main water supply system to be in a maximum flow state; S2, monitoring the main water supply system. The working state of the standby channel 120 in the system, after delaying the preset time, judge whether the standby channel 120 enters the normal working state, if so, maintain the current working state of the steam turbine 220 in the main water supply system, and trigger the main water supply regulating device 140 in the main water supply system to be in the default flow state; if not, reduce the workload of the steam turbine 220. Specifically, in the main water supply system of a nuclear power plant, feedwater is extracted from the water supply device 210 by setting multiple main feedwater passages 110 and heated by the feedwater heater, and the main feedwater regulating device 140 is opened according to the flow demand to control the steam volume of the steam generating device 150 to match the workload of the steam turbine 220. And a backup path 120 is provided, wherein the working process of the backup path 120 is controlled by the control device. Wherein, when the main water supply system is working normally, the control device detects the working status of all the main water supply channels 110 to determine whether the main water supply channels 110 are shut off. Only when the main water supply channel 110 is abnormally shut down, the standby channel 120 is triggered to start, and at the same time, the main water supply regulating device 140 is triggered to be in the maximum flow state. At this time, the main water supply system enters a transient process of operation. By setting the main water supply regulating device 140, the water flow rate of the nuclear power plant is maintained at full load. The control device is the same as the working state of the backup path 120, and counts the duration of triggering the startup of the backup path 120, and judges whether the backup path 120 has entered a normal working state after delaying for a preset time. That is, the preset time is the time during which the steam turbine 220 can maintain normal operation. The backup channel 120 works normally before and including the preset time, which will not affect the working state of the steam turbine 220. At this time, the current working state of the steam turbine 220 can be maintained, that is, full-load operation. At the same time, when the backup channel 120 enters the normal working state, adjust the main water supply regulating device 140 to return to the default flow state, that is, it is not necessary to set the main water supply regulating device 140 to the maximum flow state at this time. If the backup channel 120 does not enter the normal working state after the preset time, it can be understood that the backup channel 120 failed to connect. At this time, the steam flow taken away by the steam turbine 220 under full load conditions will be higher than the feed water flow rate, and the water level of the steam generator will continue to decrease until the low water level signal of the steam generator is triggered, resulting in an emergency shutdown. Therefore, at this time, it is necessary to reduce the workload of the steam turbine 220 so that the steam turbine 220 can work without causing an emergency shutdown.

Optionally, in a method for controlling the main water supply system of a nuclear power plant according to the present invention, it further includes triggering and generating an alarm signal when more than one main water supply channel 110 is shut down. Specifically, when the control device judges that more than one main supply channel 110 is shut down, and the control device cannot control the working state of the water supply system to alleviate the fault, the low water level signal of the steam generator will directly trigger the emergency shutdown protection signal. At this time, an alarm is directly generated for failure alarm.

Optionally, in a method for controlling the main water supply system of a nuclear power plant according to the present invention, it further includes, when the feedwater flow in the main feedwater passage 110 decreases, acquiring the degree of reduction of the feedwater flow, so as to control the flow state of the main feedwater regulating device 140 according to the degree of reduction. Specifically, the control device is also used to measure the feedwater flow rate of the main feedwater channel 110 , and when the feedwater flow rate decreases, obtain the degree of reduction of the feedwater flow rate, and control the flow state of the main feedwater regulating device 140 according to the decrease degree. In one embodiment, the opening of the main feedwater regulating valve is usually set at about 80% for normal operation. If the performance of the main feedwater pump 111 in the main feedwater passage 110 decreases, the corresponding main feedwater regulating valve will increase the valve opening according to the control signal to increase the flow.

Optionally, in a method for controlling the main water supply system of a nuclear power plant according to the present invention, it also includes, when reducing the workload of the steam turbine 220 , reducing the workload of the steam turbine 220 to 70% of the rated load of the steam turbine 220 . Specifically, when the control device reduces the workload of the steam turbine 220 because the standby channel 120 cannot enter the normal working state, the workload of the steam turbine 220 is reduced to 70% of the rated load of the steam turbine 220, so as to maintain the normal operation of the nuclear power plant.

In the present invention, by adding a spare main feedwater pump 111 to the existing main water supply system of the "three-operation spare-standby" type nuclear power plant, and configuring reasonable and feasible start-up and control logic, it is ensured that the standby pump can provide timely and sufficient feedwater flow in the scene of a running feedwater pump failure, so as to maintain the continuous operation of the nuclear power plant at full load. In addition, when the main feedwater pump 111 starts up by mistake, since the outlet electric isolation valve is a normally closed valve, the extra feedwater flow will not be able to enter the feedwater heater.

At the same time, the present invention also considers the countermeasures against the start-up failure of the standby pump. In extreme cases, a running main feed water pump 111 fails and the backup pump cannot be started as required. At this time, the nuclear power plant needs to change its operation strategy: from keeping full load operation to avoiding emergency shutdown.

It can be understood that the above examples only express the preferred implementation of the present invention, and its description is relatively specific and detailed, but it should not be interpreted as a limitation of the patent scope of the present invention; it should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, the above-mentioned technical features can be freely combined, and some deformations and improvements can also be made. These all belong to the protection scope of the present invention;

Claims (10)

1. A nuclear power plant main water supply system, characterized in that it comprises: a plurality of main water supply passages, and backup passages, feed water heating devices, main feed water regulating devices, steam generating devices, steam turbines and control devices; the main supply path and the backup path are used to connect to a water supply device, and The main supply passage and the standby passage are sequentially connected to the steam generating device via the feed water heating device and the main feed water regulating device, so as to supply water to the steam generating device; The steam generating device is connected to the steam turbine for providing working steam for the steam turbine; The control device is connected to the main water supply passage, the backup passage, the main feed water regulating device and the steam turbine, and is used to perform the following process: monitoring the working state of the main water supply channel, triggering the standby channel to start when any of the main water supply channels is shut down, and triggering the main water supply regulating device to be in the maximum flow state; monitoring the working state of the backup path, and judging whether the backup path has entered a normal working state after a preset time delay, If so, maintain the current working state of the steam turbine, and trigger the main feed water regulating device to be in a default flow state; If not, reduce the workload of the steam turbine. 2. The main water supply system of a nuclear power plant according to claim 1, wherein the main water supply passage comprises: a main feedwater pump, a first backflow regulating passage and a first non-return device; The input end of the main feed water pump is used to connect to the water supply device, the output end of the main feed water pump is connected to the input end of the first backflow regulation passage and the input end of the first check device, the output end of the first back flow adjustment passage is connected to the water supply device, the output end of the first check device is connected to the input end of the feed water heating device, and the output end of the feed water heating device is connected to the input end of the main feed water adjustment device. 3. The main water supply system of a nuclear power plant according to claim 1, wherein the backup passage comprises: a backup feedwater pump, a second backflow regulation passage and a second check device; The input end of the backup feed water pump is used to connect to the water supply device, the output end of the backup feed water pump is connected to the input end of the second backflow regulation passage and the input end of the second check device, the output end of the second back flow adjustment passage is connected to the water supply device, the output end of the second check device is connected to the input end of the feed water heating device, and the output end of the feed water heating device is connected to the input end of the main feed water adjustment device; The control device is used for triggering the standby water feed pump to work so as to trigger the standby pathway to be turned on when any one of the main water supply pathways is shut off. 4. The main water supply system of a nuclear power plant according to claim 3, wherein the backup path also includes an electric isolation device; The input end of the electric isolating device is connected to the output end of the standby feed water pump, the output end of the electric isolating device is connected to the input end of the second non-return device, and the control end of the electric isolating device is connected to the control device; The control device is used for triggering the conduction of the electric isolation device when any of the main supply channels is shut off, so as to trigger the conduction of the standby channel. 5. The main water supply system of a nuclear power plant according to claim 1, wherein the control device is further configured to trigger and generate an alarm signal when more than one main water supply channel is shut off. 6. The main water supply system of a nuclear power plant according to claim 1, wherein the control device is also used to acquire the reduction degree of the feedwater flow when the feedwater flow in the main supply passage decreases, so as to control the flow state of the main feedwater adjustment device according to the reduction degree. 7. The main water supply system of a nuclear power plant according to claim 1, wherein the nuclear power plant is a third-generation passive nuclear power plant, and the preset time is 30s. 8 . The main water supply system of a nuclear power plant according to claim 1 , wherein the plurality of main water supply passages comprise three main water supply passages. 9. The main water supply system of a nuclear power plant according to claim 1, wherein when the control device reduces the workload of the steam turbine, the workload of the steam turbine is reduced to 70% of the rated load of the steam turbine. 10. A method for controlling the main water supply system of a nuclear power plant, characterized in that it is applied to the main water supply system of a nuclear power plant according to any one of claims 1 to 9; the control method comprises: Monitoring the working status of the main water supply passages in the main water supply system, triggering the standby passage in the main water supply system to start when any of the main water supply passages is shut off, and triggering the main water supply regulating device in the main water supply system to be in the maximum flow state; monitoring the working state of the backup passage in the main water supply system, and judging whether the backup passage has entered a normal working state after delaying the preset time, If so, maintain the current working state of the steam turbine in the main water supply system, and trigger the main water supply regulating device in the main water supply system to be in a default flow state; If not, reduce the workload of the steam turbine.