Load control method and device for steam turbine generator unit of nuclear power plant

Abstract

The invention belongs to the technical field of nuclear power, and particularly relates to a load control method and device for a steam turbine generator unit of a nuclear power plant. According to the load control method for the steam turbine generator unit of the nuclear power plant, a distributed distributed control system and a digital electro-hydraulic control system of the nuclear power unit are fully utilized for logic setting; automatic load reduction of the steam turbine generator unit can be guaranteed to maintain a safe and stable operation mode of the unit; the nuclear power unit can effectively cope with two transient working conditions of circulating pump tripping and high-pressure heating splitting, and unexpected shutdown and reactor shutdown of the nuclear power unit can be effectively avoided through automatic load reduction; no new technology needs to be introduced, and the transformation cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nuclear power, and particularly relates to a load control method and device for a nuclear power plant steam turbine generator unit. BACKGROUND

[0002] Generally, the power generation principle of a nuclear power unit is to generate heat through a nuclear reactor, heat feed water in a steam generator, and then generate steam to impel a steam turbine generator unit to work and generate electric energy. The steam after working (waste steam) enters a condenser, and seawater in the condenser exchanges heat with the waste steam through heat transfer pipes, so that the seawater becomes condensed water, which is pumped into the steam generator by a condensate pump and a main feed water pump, thereby forming a circulating loop, which is referred to as a secondary loop. The seawater in the condenser heat transfer pipes flows through a circulating water pump (circulating pump) for driving, and the loop where the circulating water pump is located is referred to as a tertiary loop.

[0003] Before the main feed water pump sends water into the steam generator, the water generally needs to be heated through two parallel high-pressure heaters (high-pressure heaters). The high-pressure heater is essentially a heat exchanger, and its heating source is part of the steam extracted from the steam turbine after work, which is used to heat the feed water and then send the feed water into the steam generator, so as to improve the thermal efficiency and economy of the steam turbine generator unit.

[0004] The two high-pressure heaters are generally divided into A column and B column, each of which bears 50% of the flow of the feed water. In parallel with the two high-pressure heaters, there is a bypass pipeline. When the high-pressure heater fails, the valve on the bypass pipeline will be opened. It is worth mentioning that the bypass pipeline is generally designed to withstand only 20% to 35% of the flow of the feed water.

[0005] When a nuclear power unit fails and the steam turbine generator unit cannot maintain full load operation, it must be quickly reduced in load. The process in which a digital electro-hydraulic regulating system (DEH) quickly reduces the load of the steam turbine generator unit to the corresponding output that the unit can actually reach and controls the unit to continue running within the operating parameter range is referred to as RB (RUNBACK).

[0006] In the related art, the following factors are mainly considered in RB: the operator decides to quickly reduce the load UNLOADING; the generator stator cooling water system requires RB; the steam-water separation reheater drainage system requires RB; the electric feed water pump operating condition requires RB; and the reactor control system requires RB. The steam turbine quick load reduction control is an important means to ensure the safe operation of the unit equipment, and relevant signals are sent to the digital electro-hydraulic regulating system (DEH) system through hard wiring.

[0007] In the actual operation of the unit, when one of the two circulating water pumps trips, the flow of seawater through the condenser heat exchanger is reduced by half compared to the normal working condition, which greatly reduces the heat exchange capacity of the condenser, and further affects the overall work capacity of the entire steam turbine generator unit. The decrease in the overall work capacity of the steam turbine generator unit will inevitably lead to a decrease in efficiency. If the unit is still required to maintain full load at this time, the nuclear reactor will have to generate more heat to maintain the current full load power. The upper limit of the nuclear reactor heat power must strictly follow the limit value in the technical specification. In this case, the nuclear reactor has the risk of exceeding power, and it may trigger the over-power protection shutdown and shutdown. Therefore, in this case, the operator needs to manually reduce the unit output at a rate of 5% FP / min to match the working condition of only one circulating water pump. If the operator's manual power reduction rate cannot meet the unit's requirements, there is a risk of causing the unit to shut down and shut down.

[0008] In addition, during the actual operation of the nuclear power unit, when the single-column or double-column high-pressure heater is de-energized (i.e., the feedwater loses the heating source), the main feedwater is not heated and directly sent to the steam generator. The subcooled main feedwater will promote the nuclear reactor power to rise under the action of the negative reactivity coefficient of the nuclear reactor, and the nuclear reactor power also has the risk of exceeding the technical specification. In addition, when one or two columns of high-pressure heaters are all de-energized, the bypass pipeline can only bear 20% to 35% of the feedwater flow from the design, and the main feedwater is sent to the steam generator through the bypass pipeline of the high-pressure heater. Compared to the original flow, the steam generator's water supply is greatly reduced, and the water level is lowered, i.e., the necessary water amount for heat exchange with the nuclear reactor to cool the nuclear reactor is lacking, which can easily cause shutdown and shutdown.

[0009] In summary, according to the operation experience of the megawatt nuclear power unit, the existing RB design cannot cover the transient working conditions of circulating water pump trip and high-pressure heater de-energization, and therefore cannot meet the actual needs of safe and stable operation of the unit. SUMMARY

[0010] To overcome the problems in the related art, a nuclear power plant steam turbine generator unit load control method and device are provided.

[0011] According to an aspect of an embodiment of the present disclosure, a nuclear power plant steam turbine generator unit load control method is provided, which comprises:

[0012] The DCS system triggers the DEH system to perform RB to control the steam turbine generator unit to reduce load at a preset rate to a first target load if it detects a trip signal of any one or more circulating water pumps when the nuclear power unit is in a first power operating state. In the first power operating state, the power of the nuclear power unit is greater than or equal to the first target load.

[0013] If the DCS system monitors a water level alarm signal of a part of the high-pressure heaters indicating that the part of the high-pressure heaters is tripped, the DCS system triggers the DEH system to perform RB to control the steam turbine generator unit to reduce load to a second target load at a preset rate, and the nuclear power unit is greater than or equal to the second target load in the second power operation state.

[0014] If the DCS system monitors a water level alarm signal of all the high-pressure heaters indicating that all the high-pressure heaters are tripped, the DCS system triggers the DEH system to perform RB to control the steam turbine generator unit to reduce load to a third target load at a preset rate, and the nuclear power unit is greater than or equal to the third target load in the third power operation state.

[0015] In a possible implementation, the DCS system determines that the high-pressure heater is tripped if the DCS system monitors a water level alarm signal of the high-pressure heater indicating that the high-pressure heater is tripped to a high 3 alarm level.

[0016] In a possible implementation, the first target load is 50% FP, the second target load is 50% FP, and the third target load is 25% FP.

[0017] In a possible implementation, the preset rate is, for example, 100% FP / min.

[0018] According to another aspect of the embodiments of the present disclosure, a nuclear power plant steam turbine generator unit load control device is provided, and the device comprises:

[0019] The first monitoring control module is configured to, if the DCS system monitors a trip signal of any one or more circulating water pumps when the nuclear power unit is in a first power operation state, trigger the DEH system to perform RB to control the steam turbine generator unit to reduce load to a first target load at a preset rate, and the nuclear power unit is greater than or equal to the first target load in the first power operation state.

[0020] The second monitoring control module is configured to, if the DCS system monitors a water level alarm signal of a part of the high-pressure heaters indicating that the part of the high-pressure heaters is tripped when the nuclear power unit is in a second power operation state, trigger the DEH system to perform RB to control the steam turbine generator unit to reduce load to a second target load at a preset rate, and the nuclear power unit is greater than or equal to the second target load in the second power operation state.

[0021] The third monitoring control module is configured to, if the DCS system monitors a water level alarm signal of all the high-pressure heaters indicating that all the high-pressure heaters are tripped when the nuclear power unit is in a third power operation state, trigger the DEH system to perform RB to control the steam turbine generator unit to reduce load to a third target load at a preset rate, and the nuclear power unit is greater than or equal to the third target load in the third power operation state.

[0022] In a possible implementation, if the DCS system monitors that the high-pressure heater is tripped to a high 3 alarm water level, it is determined that the high-pressure heater is tripped.

[0023] In a possible implementation, the first target load is 50% FP, the second target load is 50% FP, and the third target load is 25% FP.

[0024] In a possible implementation, the preset rate is, for example, 100% FP / min.

[0025] According to another aspect of the embodiments of the present disclosure, a nuclear power plant steam turbine generator unit load control device is provided, and the device comprises:

[0026] a processor;

[0027] a memory for storing processor-executable instructions;

[0028] The processor is configured to perform the method described above.

[0029] According to another aspect of the embodiments of the present disclosure, a nonvolatile computer-readable storage medium is provided, which stores computer program instructions, and the computer program instructions are executed by a processor to implement the method described above.

[0030] The present disclosure has the following beneficial effects: The nuclear power plant steam turbine generator unit load control method provided by the present disclosure makes full use of the distributed control system (DCS) and the digital electro-hydraulic control system (DEH) of the nuclear power unit to perform logic setting, can automatically trigger the nuclear power steam turbine generator unit load reduction action when the circulating pump tripping and high-pressure heater tripping transient conditions occur, and can make the nuclear power unit automatically reduce the load at a set rate, so that the electric power can be maintained at a set target value, while ensuring that the nuclear reactor related parameters meet the requirements of the technical specification, thereby ensuring the safe operation of the nuclear power unit and avoiding shutdown and shutdown. In addition, when the single circulating water pump tripping, single high-pressure heater tripping, double high-pressure heater tripping, and other transient conditions occur, the distributed control system (DCS) and the digital electro-hydraulic control system (DEH) of the nuclear power unit are combined, and the two systems cooperate with each other to realize the function of automatically and quickly reducing the load when the nuclear power unit is in a certain transient condition, thereby effectively avoiding human errors that may occur during the operation of the operator. The nuclear power unit can effectively cope with the circulating pump tripping and high-pressure heater tripping transient conditions, and the automatic load reduction can effectively avoid the unexpected shutdown and shutdown of the nuclear power unit; without introducing new technology, the modification cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a schematic diagram of a nuclear power plant steam turbine generator unit load control method according to an embodiment of the present disclosure.

[0032] Figure 2 is a block diagram of a nuclear power plant steam turbine generator unit load control device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] The present disclosure will be further described in conjunction with the drawings and specific embodiments.

[0034] Unless otherwise defined, technical and scientific terms used in the present disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs; the terminology used in the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure; the use of the term "including" and "comprising" in the description of the disclosure is not intended to be limiting of the present disclosure; the term "consisting essentially of" is intended to mean including an amount of an ingredient other than those recited in the list of ingredients; it is understood that the present disclosure is not limited to the embodiments described herein, which are intended as illustrations only; it is intended to cover any and all modifications of the embodiments within the scope of the present disclosure; and, any and all embodiments of the disclosure can be used alone or in combination with one another.

[0035] Reference to "an embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment. It is expressly understood that any of the embodiments described herein can be incorporated separately or in combination with any other embodiment.

[0036] Figure 1 is a schematic diagram of a nuclear power plant steam turbine generator unit load control method according to an embodiment of the present disclosure. Referring to Figure 1 , if the DCS system detects a trip signal of any one or more circulating water pumps when the nuclear power unit is in a first power operation state (in the first power operation state, the power of the nuclear power unit is greater than or equal to a first target load), the DCS system triggers the DEH system to perform RB to control the steam turbine generator unit to reduce load to the first target load (the first target load can be 50% FP) at a preset rate (the preset rate can be, for example, 100% FP / min). Thus, the steam turbine generator unit can automatically reduce load after any one or more circulating water pumps trip.

[0037] If the DCS system monitors a water level alarm signal of any one or more high-pressure heaters as a high-3 alarm water level in a second power operation state of the nuclear power unit (in the second power operation state, the power of the nuclear power unit is greater than or equal to a second target load), it is determined that the one or more high-pressure heaters are tripped, and the DEH system is triggered to perform RB to control the steam turbine generator unit to reduce the load to the second target load (the second target load can be 50% FP) at a preset rate. Thus, the steam turbine generator unit can automatically reduce the load after any one or more high-pressure heaters are tripped. For example, the DCS system collects an “A-row high-pressure heater water level” signal and a “B-row high-pressure heater water level” signal, respectively, to trigger an “A-row high-pressure heater trip” signal and a “B-row high-pressure heater trip” signal, respectively, when the signals reach a “high-3” water level alarm.

[0038] If the DCS system monitors a water level alarm signal of all high-pressure heaters as a high-3 alarm water level in a third power operation state of the nuclear power unit (in the third power operation state, the power of the nuclear power unit is greater than or equal to a third target load), it is determined that all high-pressure heaters are tripped, and the DEH system is triggered to perform RB to control the steam turbine generator unit to reduce the load to the third target load (the third target load can be 25% FP) at a preset rate.

[0039] The first target load, the second target load, the third target load, and the preset rate can be adaptively adjusted according to the actual operation of the nuclear power unit. Thus, the RB load point and the load reduction rate value can be adjusted according to the actual operation of the nuclear power unit, which is highly operable and flexible to adapt to different nuclear power unit industrial control scenarios. In addition, the above method can also be used to verify the effect on a million-kilowatt nuclear power unit full-range simulation simulator.

[0040] In one possible implementation, a nuclear power plant steam turbine generator unit load control device is provided, characterized in that the device comprises:

[0041] A first monitoring control module is configured to, in a first power operation state of the nuclear power unit (in the first power operation state, the power of the nuclear power unit is greater than or equal to a first target load), if a trip signal of any one or more circulating water pumps is monitored, trigger the DEH system to perform RB to control the steam turbine generator unit to reduce the load to the first target load at a preset rate.

[0042] A second monitoring control module is configured to, in a second power operation state of the nuclear power unit (in the second power operation state, the power of the nuclear power unit is greater than or equal to a second target load), if a water level alarm signal of part of the high-pressure heaters indicates that the part of the high-pressure heaters are tripped, trigger the DEH system to perform RB to control the steam turbine generator unit to reduce the load to the second target load at a preset rate.

[0043] The third monitoring control module is configured to, when the nuclear power unit is in a third power operation state, if all the water level alarm signals of the high-pressure heaters indicate that all the high-pressure heaters are tripped, triggering the DEH system to perform RB to control the steam turbine generator unit to reduce load to a third target load at a preset rate, and in the third power operation state, the power of the nuclear power unit is greater than or equal to the third target load.

[0044] In a possible implementation, the DCS system determines that the high-pressure heater is tripped if it is monitored that the high-pressure heater is tripped to a high 3 alarm water level.

[0045] In a possible implementation, the first target load is 50% FP, the second target load is 50% FP, and the third target load is 25% FP.

[0046] In a possible implementation, the preset rate is, for example, 100% FP / min.

[0047] The description of the above device has been described in detail in the description of the above method, and will not be repeated here.

[0048] Figure 2 is a block diagram of a nuclear power plant steam turbine generator unit load control device according to an embodiment of the present disclosure. For example, the device 1900 can be provided as a server. Referring to Figure 2 , the device 1900 includes a processing assembly 1922, which further includes one or more processors, and a memory resource represented by a memory 1932, for storing instructions, such as application programs, executable by the processing assembly 1922. The application programs stored in the memory 1932 can include one or more than one module each corresponding to a set of instructions. In addition, the processing assembly 1922 is configured to execute the instructions to perform the above method.

[0049] The device 1900 can also include a power supply assembly 1926 configured to perform power management of the device 1900, a wired or wireless network interface 1950 configured to connect the device 1900 to a network, and an input / output (I / O) interface 1958. The device 1900 can operate based on an operating system stored in the memory 1932, such as Windows ServerTM, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM or the like.

[0050] In an exemplary embodiment, a non-volatile computer readable storage medium, such as the memory 1932 including computer program instructions executable by the processing assembly 1922 of the device 1900 to perform the above method, is also provided.

[0051] The present disclosure can be a system, a method, and / or a computer program product. The computer program product can include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present disclosure.

[0052] The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium can be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or punched tape, a

[0053] The computer readable program instructions described herein can be downloaded to respective computing / processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and / or a wireless network. The network can comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing / processing device.

[0054] Computer readable program instructions for carrying out operations of the present disclosure can be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate array (FPGA), or programmable logic array (PLA) can execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present disclosure.

[0055] The computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0056] These computer readable program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. These computer readable program instructions can also be stored in a computer readable storage medium that can include random access memory (RAM), read only memory (ROM), electrically erasable programmable read only memory (EEPROM), flash memory or other data storage device. When the computer readable program instructions are loaded into the computer and other programmable data processing apparatus, a series of operational steps are implemented that provide processes such that the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0057] The computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer, other programmable data processing apparatus, or other device implement the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0058] The flow diagrams and the block diagrams in the drawings are presented to illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flow diagrams and the block diagrams can represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logic functions. In some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flow diagrams, and combinations thereof, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and

[0059] Embodiments of the present disclosure have been described above, and the description is intended to be illustrative of the embodiments and not restrictive. Many modifications and variations of the described embodiments are possible and are within the scope of the disclosure. The selection of terms is intended to best describe the principles of the embodiments, practical application, or improvement over the technology in the art, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A load control method for a steam turbine generator set in a nuclear power plant, characterized in that, The method includes: If the DCS system detects a trip signal of any one or more circulating water pumps when the nuclear power unit is operating at the first power level, it will trigger the DEH system to execute RB to control the turbine generator unit to reduce the load to the first target load at a preset rate. In the first power operation state, the power of the nuclear power unit is greater than or equal to the first target load. If the DCS system detects a water level alarm signal from some high-pressure heaters indicating that those high-pressure heaters should be disconnected when the nuclear power unit is in the second power operation state, it will trigger the DEH system to execute RB to control the turbine generator unit to reduce the load to the second target load at a preset rate. In the second power operation state, the power of the nuclear power unit is greater than or equal to the second target load. When the nuclear power unit is in the third power operation state, if the DCS system detects that all high-pressure heaters have water level alarm signals indicating that all high-pressure heaters are disconnected, it will trigger the DEH system to execute RB to control the turbine generator unit to reduce the load to the third target load at a preset rate. In the third power operation state, the power of the nuclear power unit is greater than or equal to the third target load.

2. The method according to claim 1, characterized in that, If the DCS system detects that the high-pressure heater has been disconnected and the alarm water level is high 3, then it determines that the high-pressure heater has been disconnected.

3. The method according to claim 1, characterized in that, The first target load is 50% FP, the second target load is 50% FP, and the third target load is 25% FP.

4. The method according to claim 1, characterized in that, The preset rate is, for example, 100% FP / min.

5. A load control device for a nuclear power plant turbine generator set, characterized in that, The device includes: The first monitoring and control module is used to trigger the DEH system to execute RB if any one or more circulating water pumps trip signals are detected when the nuclear power unit is in the first power operation state, so as to control the turbine generator unit to reduce the load to the first target load at a preset rate. In the first power operation state, the power of the nuclear power unit is greater than or equal to the first target load. The second monitoring and control module is used to trigger the DEH system to execute RB when the nuclear power unit is in the second power operation state. If the water level alarm signal of some high-pressure heaters is detected, indicating that some high-pressure heaters are disconnected, the module controls the turbine generator unit to reduce the load to the second target load at a preset rate. In the second power operation state, the power of the nuclear power unit is greater than or equal to the second target load. The third monitoring and control module is used to trigger the DEH system to execute RB when the nuclear power unit is in the third power operation state. If the water level alarm signal of all high-pressure heaters indicates that all high-pressure heaters are disconnected, the module will control the turbine generator unit to reduce the load to the third target load at a preset rate. In the third power operation state, the power of the nuclear power unit is greater than or equal to the third target load.

6. The apparatus according to claim 1, characterized in that, If the DCS system detects that the high-pressure heater has been disconnected and the alarm water level is high 3, then it determines that the high-pressure heater has been disconnected.

7. The apparatus according to claim 1, characterized in that, The first target load is 50% FP, the second target load is 50% FP, and the third target load is 25% FP.

8. The apparatus according to claim 1, characterized in that, The preset rate is, for example, 100% FP / min.

9. A load control device for a steam turbine generator set in a nuclear power plant, characterized in that, The device includes: processor; Memory used to store processor-executable instructions; The processor is configured to perform the method according to any one of claims 1 to 4.

10. A non-volatile computer-readable storage medium storing computer program instructions thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the method described in any one of claims 1 to 4.

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