Control system and method for standby power supply of nuclear power plant

Abstract

The invention discloses a control system and method for a standby power supply of a nuclear power plant, and the method comprises the following steps: detecting the voltage of a reliable medium-voltage factory bus EMA, and judging whether a corresponding first voltage signal meets a first preset condition or not; if the first preset condition is met, the first voltage signal is sent to a master control room; the master control room sends a standby power supply starting signal to the parallel control cabinet through the control system to start the standby power supply; the parallel control cabinet judges whether the operation parameters corresponding to the standby power supply reach preset synchronization conditions or not; if the operation parameters reach the preset synchronization condition, the parallel control cabinet sends a parallel switching signal to the parallel switch cabinet, so that the standby power supply is connected to the EMC in parallel; after the standby power supplies are connected in parallel, the master control room sends an opening command to the first circuit breaker; and after the first circuit breaker finishes opening, the main control room sends a closing command to the second circuit breaker, so that the standby power supply supplies power to the reliable medium-voltage plant bus EMA.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and in particular to a control system and method for a nuclear power plant backup power supply. Background Art

[0002] In order to ensure the safe shutdown of the reactor in the event of loss of all off-site power supplies and main generators, the nuclear power reactors in service around the world and new reactors such as active and passive pressurized water reactors under development in my country are equipped with high-power generator sets as in-plant emergency or backup power supplies to provide reliable, long-term and stable power for the power equipment used in the plant to ensure safe shutdown and investment protection. At present, they have the disadvantages of large single-unit capacity, high procurement costs, high plant cost, difficult testing and low operational flexibility. At present, the candidate models of backup generator sets that can be used in nuclear power plants are all single high-power units, and the models available are limited. In addition, in the first 20 years of operation of nuclear power plants built in the early stage of China, major maintenance nodes such as the return of diesel generator sets to the factory for overhaul have not appeared on a large scale.

[0003] The existing patent CN102856975A discloses a backup power automatic input system, which includes: a first detection module for detecting the current and voltage values ​​of the main power supply; a second detection module for detecting the voltage value of the backup power supply; a signal processing module for generating and outputting a switching signal to a switching switch according to preset parameters when the current and voltage values ​​of the main power supply are zero and the voltage value of the backup power supply is not zero; a switching switch for connecting the bus of the backup power supply according to the switching signal; a static switch for connecting the energy storage device to the bus of the main power supply when the current and voltage values ​​of the main power supply are zero; when the voltage value of the output end of the switching switch is not zero, connecting the output end of the switching switch to the bus of the main power supply; an energy storage device for storing electrical energy. This solution focuses on the automatic access process of the backup power supply, and does not make relevant designs for the backup power supply.

[0004] The existing patent CN202178605U discloses a power plant security power supply automatic switch control system, which belongs to the field of power failure processing technology. The system includes: a standby automatic switch control module, which is used to start the mains standby power supply when the mains working power supply fails; a diesel engine start control module, which is used to start the diesel engine power supply when the standby automatic switch control module cannot start the mains standby power supply; a diesel engine load test work control module, which is used to detect the diesel engine to ensure that the diesel engine is available; a working power supply switchback control module, which is used to switch back to the mains working power supply when the mains working power supply is restored. This solution focuses on the automatic access of the standby power supply, which adopts the method of selecting one of the multiple standby power supplies for power supply, which has the problems of high cost, long switching time and high dimensional difficulty.

[0005] In summary, the above two existing patents have not designed a corresponding backup power supply control system for the nuclear power field, and have not solved the problems of high cost, difficult testing and low operational flexibility of a single backup power supply in the prior art. Summary of the invention

[0006] Based on the above technical problems, the present invention proposes a control system and method for a nuclear power plant backup power supply to solve the problems of high cost, difficult testing and low operational flexibility of a single backup power supply in the prior art.

[0007] To achieve the above object, the present invention provides a control system for a nuclear power plant backup power supply.

[0008] A control system for a nuclear power plant backup power supply, comprising: a main generator, a main generator circuit breaker, a main transformer, an off-site main power supply, a high-voltage plant transformer, an off-site auxiliary power supply, an auxiliary transformer, a normal medium-voltage plant bus ESA and a first-category target load, and further comprising: a first circuit breaker, a reliable medium-voltage plant bus EMA, a second circuit breaker, a second-category target load, a backup power supply parallel bus EMC, a third circuit breaker and a backup power supply,

[0009] The main generator is connected to the main power source outside the factory through the main generator circuit breaker and the main transformer to supply power to the power system outside the factory;

[0010] The main generator is connected to the normal medium voltage plant bus ESA through a high voltage plant transformer to supply power to the normal medium voltage plant bus ESA;

[0011] The main power supply outside the plant is connected to the normal medium-voltage plant bus ESA through the main transformer and the high-voltage plant transformer, and is used to supply power to the normal medium-voltage plant bus ESA;

[0012] The off-site auxiliary power supply is connected to the normal medium-voltage plant bus ESA through an auxiliary transformer. The off-site auxiliary power supply is used to supply power to the normal medium-voltage plant bus ESA when the off-site main power supply is lost;

[0013] The backup power parallel bus EMC is connected to the reliable medium-voltage plant bus EMA and the backup power supply through the second circuit breaker and the third circuit breaker, respectively, so that when the main generator, the off-site main power supply and the off-site auxiliary power supply are all lost, the backup power supply supplies power to the backup power parallel bus EMC, and the backup power parallel bus EMC distributes power to the reliable medium-voltage plant bus EMA;

[0014] The normal medium-voltage plant busbar ESA is connected to the first type of target load, and is used to supply power to the first type of target load; the normal medium-voltage plant busbar ESA is also connected to the reliable medium-voltage plant busbar EMA through the first circuit breaker, and is used to supply power to the reliable medium-voltage plant busbar EMA;

[0015] The reliable medium-voltage plant bus EMA is connected to the second-category target load and is used to supply power to the second-category target load.

[0016] Furthermore, a high voltage plant transformer is tapped between the main generator circuit breaker and the main transformer.

[0017] Furthermore, the backup power source is a diesel generator set.

[0018] Furthermore, each diesel generator set is provided with a corresponding electrical cabinet, which includes a local control cabinet, a PLC control and synchronization cabinet, a speed regulation and protection cabinet and a voltage transformer cabinet.

[0019] Furthermore, when the main generator, the off-site main power supply and the off-site auxiliary power supply are all lost, the starting condition of the backup power supply is: the voltage of the reliable medium-voltage plant bus EMA is lower than 0.8Un, and the voltage duration is greater than or equal to 0.9s.

[0020] Furthermore, the input condition of the backup power supply is: the voltage of the reliable medium-voltage plant bus EMA is within the range of 0 to 0.8 V, and the voltage duration is greater than or equal to 5 seconds.

[0021] In order to achieve the same purpose as the above system, the present invention also proposes a control method for a nuclear power plant backup power supply.

[0022] A method for controlling a backup power supply of a nuclear power plant, comprising:

[0023] The electrical cabinet detects the voltage of the reliable medium-voltage plant bus EMA, and determines whether the corresponding first voltage signal meets the first preset condition;

[0024] If the first voltage signal meets the first preset condition, the first voltage signal is sent to the main control room through the control system;

[0025] The main control room sends the backup power supply start signal to the parallel control cabinet through the control system to start the backup power supply;

[0026] The parallel control cabinet determines whether the operating parameters corresponding to the backup power supply meet the preset synchronization conditions;

[0027] If the operating parameters reach the preset synchronization conditions, the parallel control cabinet sends a parallel connection signal to the parallel switch cabinet to connect the backup power supply to the EMC in parallel, and sends the parallel connection signal of the backup power supply to the control system;

[0028] When the backup power supply is connected in parallel, the main control room sends a trip command to the first circuit breaker through the control system;

[0029] When the first circuit breaker is opened, the main control room sends a closing command to the second circuit breaker through the control system, so that the backup power supply can supply power to the reliable medium-voltage plant bus EMA.

[0030] Furthermore, the first preset condition is that the voltage value of the first voltage signal is lower than 0.8Un, and the duration of the voltage value is greater than or equal to 0.9s.

[0031] Furthermore, after starting the backup power supply, the method further includes:

[0032] The electrical cabinet detects and determines whether the second voltage signal meets a second preset condition;

[0033] If the second voltage signal meets the second preset condition, it is determined that the current main generator is tripped, and both the external main power supply and the external auxiliary power supply are lost, and the second voltage signal is sent to the main control room.

[0034] Furthermore, the second preset condition is that the voltage value of the second voltage signal is in the range of 0 to 0.8 V, and the duration of the voltage value is greater than or equal to 5 s.

[0035] Furthermore, the operating parameters include voltage, phase and frequency, and judging whether the operating parameters corresponding to the backup power supply meet the preset synchronization conditions includes:

[0036] Determine whether the voltage, phase and frequency of each diesel generator set in the backup power supply are the same;

[0037] If the voltage, phase and frequency of each diesel generator set are the same, it is determined that the operating parameters have reached the preset synchronization condition.

[0038] Furthermore, before determining whether the operating parameters corresponding to the backup power supply have reached the preset synchronization condition, the method further includes:

[0039] Determine whether the voltage of each diesel generator set in the backup power supply has reached the rated voltage, and whether the frequency has reached the rated frequency;

[0040] If the voltage of each diesel generator set has reached the rated voltage and the frequency has reached the rated frequency, the electrical cabinet will send the corresponding signal to the control system.

[0041] Furthermore, it also includes:

[0042] When the first circuit breaker is opened and the opening state lasts for 1s to 2s, the parallel switch cabinet sends a first circuit breaker opening completion signal to the control system;

[0043] When the control system receives the opening completion signal of the first circuit breaker, the main control room sends a closing command of the second circuit breaker through the control system.

[0044] Furthermore, after the main control room sends a closing command to the second circuit breaker through the control system, the power supply load is loaded according to a preset loading program.

[0045] Based on the above technical solution, the present invention has at least the following beneficial effects:

[0046] 1. The present invention uses multiple diesel generator sets in parallel as backup power supply, and automatically starts the backup power supply when the preset conditions are met by real-time detection and judgment of the voltage signal of the reliable medium-voltage plant bus EMA, completes the loading of the power supply load and quickly enters a stable operation state. In actual operation, if it is detected that the total power of the load is less than the total power of the unit, and the value is higher than the rated power of a single diesel generator set, a generator set can be intelligently unloaded through the control device, so that the parallel diesel generator sets can operate at a state close to full power, while ensuring the reliability of the unit and improving the flexibility and efficiency of the overall operation.

[0047] 2. The present invention adopts a method of connecting multiple diesel generator sets in parallel as a backup power supply. When a unit fails, especially in extreme cases where it needs to be returned to the factory for overhaul, it can be quickly replaced by borrowing a mobile diesel generator set of corresponding power, which can improve the subsequent operation and maintenance efficiency and unit reliability.

[0048] 3. The present invention uses a parallel control cabinet to determine whether the corresponding operating parameters of the backup power supply meet the preset synchronous conditions, ensuring that the backup power supply can be connected to the power grid at an appropriate time. After the backup power supply is connected in parallel, the main control room can accurately control the opening and closing operations of the circuit breaker to ensure that the backup power supply is smoothly switched to the main power supply state and reduce the power supply interruption time. This method can ensure that when the main generator or off-site power supply fails, the backup power supply is quickly and automatically put into operation, thereby improving the reliability and continuity of the power supply and ensuring stable power supply to critical loads during peak power demand or emergency situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0050] Figure 1 A schematic diagram of a control system for a nuclear power plant backup power supply according to an embodiment of the present invention;

[0051] Figure 2 A flow chart of a control method for a nuclear power plant backup power supply according to an embodiment of the present invention;

[0052] Figure 3The figure is a schematic diagram of the relationship between related controls involved in a method for controlling a backup power supply of a nuclear power plant according to an embodiment of the present invention.

[0053] The above drawings include the following reference numerals:

[0054] 100. Main generator; 101. Main generator circuit breaker; 102. Main transformer; 200. External main power supply; 300. High-voltage plant transformer; 400. External auxiliary power supply; 401. Auxiliary transformer; 500. Normal medium-voltage plant bus ESA; 501. First-class target load; 502. First circuit breaker; 600. Reliable medium-voltage plant bus EMA; 601. Second circuit breaker; 602. Second-class target load; 700. Backup power supply; 701. Third circuit breaker; 800. Backup power supply parallel bus EMC. DETAILED DESCRIPTION

[0055] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0056] The present invention is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed by the present invention.

[0057] Example

[0058] In order to solve the problems of high cost, difficult testing and low operational flexibility of a single backup power supply in the prior art, the present invention proposes a control system and method for a backup power supply of a nuclear power plant.

[0059] To achieve the above object, the present invention provides a control system for a nuclear power plant backup power supply.

[0060] like Figure 1 FIG. 4 is a schematic diagram of a control system for a nuclear power plant backup power supply according to an embodiment of the present invention. Figure 1 As shown, the control system includes: main generator 100, main generator circuit breaker 101, main transformer 102, off-site main power supply 200, high-voltage plant transformer 300, off-site auxiliary power supply 400, auxiliary transformer 401, normal medium-voltage plant bus ESA500, first-class target load 501, first circuit breaker 502, reliable medium-voltage plant bus EMA600, second circuit breaker 601, second-class target load 602, backup power supply 700, third circuit breaker 701 and backup power parallel bus EMC800. The relationship between each component and its function will be introduced below.

[0061] The main generator 100 is connected to the off-site main power supply 200 through the main generator circuit breaker 101 and the main transformer 102, and is used to supply power to the off-site power system; the main generator 100 is also connected to the normal medium-voltage plant bus ESA500 through the high-voltage plant transformer 300, and is used to supply power to the normal medium-voltage plant bus ESA500. The high-voltage plant transformer 300 is tapped between the main generator circuit breaker 101 and the main transformer 102.

[0062] The off-site power supply includes an off-site main power supply 200 and an off-site auxiliary power supply 400. The off-site main power supply 200 is connected to the normal medium-voltage plant bus ESA500 through the main transformer 102 and the high-voltage plant transformer 300, and is used to supply power to the normal medium-voltage plant bus ESA500; the off-site auxiliary power supply 400 is connected to the normal medium-voltage plant bus ESA500 through the auxiliary transformer 401, and the off-site auxiliary power supply 400 is used to supply power to the normal medium-voltage plant bus ESA500 when the off-site main power supply 200 is lost.

[0063] The normal medium-voltage plant bus ESA500 is connected to the first type of target load 501, and is used to supply power to the first type of target load 501; the normal medium-voltage plant bus ESA500 is also connected to the reliable medium-voltage plant bus EMA600 through the first circuit breaker 502, and is used to supply power to the reliable medium-voltage plant bus EMA600. The reliable medium-voltage plant bus EMA600 is connected to the second type of target load 602, and is used to supply power to the second type of target load 602. When the normal medium-voltage plant bus ESA500 is energized, it indicates that it can supply power to the reliable medium-voltage plant distribution device, that is, the current situation is the normal operation of the nuclear power plant, combined with Figure 1 For example, in this case, the first circuit breaker 502 is normally closed (manually operating a switch in the workstation of the main control room of the nuclear power plant can close the first circuit breaker), the second circuit breaker 601 is normally open, and the medium-voltage plant bus EMA600 is powered by the normal medium-voltage plant bus ESA.

[0064] The backup power supply 700 refers to the power supply after the main generator 100 trips and the external main power supply 200 and the external auxiliary power supply 400 are lost in the reliable medium-voltage plant power system. The backup power supply 700 is connected to the backup power parallel bus EMC800 through the third circuit breaker 701, and the backup power parallel bus EMC800 is connected to the reliable medium-voltage plant bus EMA600 through the second circuit breaker 601, which is used for supplying power to the reliable medium-voltage plant bus EMA600 through the backup power supply 700 when the main generator 100, the external main power supply 200 and the external auxiliary power supply 400 are all lost. Further, the backup power supply 700 in this embodiment is a plurality of diesel generator sets EMP~EMX.

[0065] Based on the relationship and functional description between the above control system components, it can be understood that during the normal operation of the nuclear power plant, the reliable medium-voltage plant bus EMA600 is powered by its corresponding normal plant power distribution system (i.e., the main generator, the main power supply outside the plant, and the auxiliary power supply outside the plant). In the case where the main generator 100 trips and loses the power supply outside the plant, the diesel generator set running in parallel can supply power to the second type of target load 602 under the reliable medium-voltage plant bus EMA600. At this time, the first circuit breaker 502 is disconnected, and the second circuit breaker 601 is closed after starting the parallel diesel generator set EMP~EMX, so that the diesel generator set sequentially supplies power to multiple second type target loads 602 through the backup power parallel bus EMC800 and the reliable medium-voltage plant bus EMA. The second type of target load 602 refers to the plant power equipment that must be kept in continuous operation or continuous power supply under the conditions of starting, normal operation, normal shutdown and loss of all power supplies outside the plant. This type of plant power equipment allows power outages for a certain period of time, such as equipment cooling water units, important plant water pumps and fire pumps.

[0066] Specifically, when the main generator 100, the off-site main power supply 200 and the off-site auxiliary power supply 400 are all lost, and the normal power supply is switched to the backup power supply diesel generator set, the starting condition of the backup power supply 700 is: the voltage of the reliable medium-voltage plant bus EMA600 is in a low voltage state, the low voltage value is within the range of 0 to 0.8Un (Un represents the rated voltage), and the voltage duration is greater than or equal to 0.9s. When the diesel generator set is in a ready state (that is, the diesel generator set reaches the preset synchronization condition), and the low voltage duration is greater than or equal to 5s, the first circuit breaker 502 trips, and the selected plant equipment is cut off according to the loading program. After the delay of the interlock between the first circuit breaker 502 and the second circuit breaker 601, the second circuit breaker 601 is closed, and the cut-off plant power equipment is restarted. It should be noted that when the power supply is switched from the normal plant distribution device to the backup power supply diesel generator set, the plant load is swept and reloaded.

[0067] Furthermore, the input condition of the backup power supply 700 is: the voltage of the reliable medium-voltage plant bus EMA600 is within the range of 0 to 0.8V, and the voltage duration is greater than or equal to 5s. Specifically, when the backup power diesel generator set switches to the normal power supply, the diesel generator set supplies power. If the voltage is detected on the reliable medium-voltage plant bus within the range of 0 to 0.8V and reaches a preset duration greater than or equal to 5s, the second circuit breaker 601 is disconnected and the first circuit breaker 502 is closed.

[0068] In this embodiment, a container-type medium-voltage diesel generator set is used as an emergency or backup power source in the factory, and an outdoor open-air layout is adopted. When the diesel generator set is connected in parallel as a backup power supply, a certain diesel generator set can be unloaded through the control device, so that other generator sets running in parallel work at a state close to their maximum output power, thereby improving power generation efficiency and reducing energy waste. In addition, when multiple diesel generator sets are running in parallel, if a certain diesel generator set fails and an extreme situation occurs in which it needs to be returned to the factory for overhaul, a mobile diesel generator set of corresponding power can be rented from the market or borrowed from the local power department for replacement. For the site of a multi-core power unit, a movable medium-voltage diesel generator set can be pre-equipped, or the originally configured medium-voltage mobile power supply can be used as a backup to ensure that the power supply capacity can be quickly restored in an emergency, thereby minimizing downtime and ensuring the continuity and stability of power supply.

[0069] Furthermore, each diesel generator set is equipped with a corresponding electrical cabinet, which includes a local control cabinet, a PLC control and synchronization cabinet, a speed regulation and protection cabinet, and a voltage transformer cabinet. An industrial-grade touch screen (HMI) is installed on the front door panel of the local control cabinet, which is connected to the PLC through a communication line to realize data monitoring, alarm, recording and storage functions. The PLC control and synchronization cabinet mainly realizes the control and protection of the non-safety-level circuit of the unit and the monitoring of thermal parameters of each system. The non-safety-level circuit control is realized by a programmable logic controller (PLC), which includes input and output cards for circuit signal processing, receives input signals from various sensors on the diesel generator set and its auxiliary system, and can also receive analog and switch interface signals from the power plant. The acquisition channel reserves 15% of the spare margin. The speed regulation and protection cabinet realizes diesel engine speed control, overspeed protection and generator protection functions. A speed controller is installed in the cabinet, and receives the speed sensor signal on the diesel engine to control the diesel engine speed. The diesel engine start mode (idle, rated speed fast start and slow start) is determined by the external switch input state. The speed controller outputs 0-200mA current signal to drive the actuator on the diesel engine, adjust the fuel injection amount, control the speed and load, and the circuit is equipped with a corresponding current monitoring device and sent to the HMI for display. The voltage transformer cabinet is mainly used to obtain the voltage transformer and related supporting equipment for the relay protection, measurement, voltage regulation and synchronous function voltage signals of the diesel generator set.

[0070] It should be noted that for the load carried by the reliable medium-voltage plant bus, since the starting power of the motor is greater than its rated power, the capacity of the standby diesel generator set is not selected according to the simultaneous start of all the plant power equipment powered by the reliable medium-voltage plant power distribution device, and a loading program must be specified. The loading program is controlled by the operation control system logic program. Once the reliable medium-voltage plant bus has low voltage, the first circuit breaker trips, and the unloading program starts from the receipt of the first circuit breaker trip approval signal, and the timing starts at the moment the second circuit breaker corresponding to the standby power diesel generator is closed.

[0071] In order to achieve the same purpose as the above system, the present invention also proposes a control method for a nuclear power plant backup power supply.

[0072] Figure 2 A flow chart of a method for controlling a backup power supply of a nuclear power plant according to an embodiment of the present invention is shown in FIG. Figure 3 A schematic diagram showing the relationship between the related controls involved in the above control method is shown in FIG. Figure 3 As shown, the relevant control includes a main control room, a parallel control cabinet, a parallel switch cabinet, parallel diesel generators EMP~EMX and electrical cabinets P~X corresponding to each diesel generator. The main control room is connected to the parallel control cabinet, which is used to send control instructions to the parallel control cabinet. The parallel control cabinet receives the instructions from the main control room, executes the corresponding parallel control operations, and feeds back the operating status and fault information of the equipment to the main control room; the parallel control cabinet is connected to the parallel switch cabinet, and the parallel switch cabinet is used to execute the control instructions issued by the parallel control cabinet. The following will be combined with Figure 2 and Figure 3 Introduce the steps of the control method.

[0073] S1, the electrical cabinet detects the voltage of the reliable medium-voltage plant bus EMA, and determines whether the corresponding first voltage signal meets a first preset condition.

[0074] Furthermore, the first preset condition is that the voltage value of the first voltage signal is lower than 0.8Un, and the duration of the voltage value is greater than or equal to 0.9s.

[0075] S2: If the first voltage signal meets the first preset condition, the first voltage signal is sent to the main control room through the control system.

[0076] S3, the main control room sends the backup power supply start-up signal to the parallel control cabinet through the control system to start the backup power supply.

[0077] In another embodiment of the present invention, after executing step S3 to start the backup power supply, the electrical cabinet continues to detect the voltage of the reliable medium-voltage plant bus EMA, and determines the current power supply status based on the detected voltage. The specific process is as follows: the electrical cabinet detects and determines whether the second voltage signal meets the second preset condition; if the second voltage signal meets the second preset condition, it is determined that the current main generator 100 is tripped, and the main power supply outside the factory and the auxiliary power supply outside the factory have been lost, and the second voltage signal is sent to the main control room. Furthermore, the second preset condition is that the voltage value of the second voltage signal is in the range of 0 to 0.8v, and the duration of the voltage value is greater than or equal to 5s.

[0078] S4, the parallel control cabinet determines whether the operating parameters corresponding to the backup power supply meet the preset synchronization conditions.

[0079] Furthermore, the process of determining whether the operating parameters corresponding to the backup power supply meet the preset synchronization conditions is as follows: determine whether the voltage, phase and frequency of each diesel generator set in the backup power supply are the same; if the voltage, phase and frequency of each diesel generator set are the same, it is determined that the operating parameters have reached the preset synchronization conditions.

[0080] In another embodiment of the present invention, before determining whether the operating parameters corresponding to the backup power supply meet the preset synchronization conditions, the operating conditions of each diesel generator set in the backup power supply are detected and determined, and the specific process is as follows: determine whether the voltage of each diesel generator set in the backup power supply has reached the rated voltage, and whether the frequency has reached the rated frequency; if the voltage of each diesel generator set has reached the rated voltage, and the frequency has reached the rated frequency, the electrical cabinet will send the corresponding signal to the control system.

[0081] S5, if the operating parameters reach the preset synchronization conditions, the parallel control cabinet sends a parallel connection signal to the parallel switch cabinet to connect the backup power supply in parallel to the EMC, and sends a signal that the backup power supply has completed parallel connection to the control system.

[0082] S6: After the backup power supply is connected in parallel, the main control room sends a trip command to the first circuit breaker through the control system.

[0083] When the backup power supply is connected in parallel, the main control room sends a trip command to the first circuit breaker to disconnect the first circuit breaker, preparing to switch from the main generator and the off-site power supply to the backup power supply.

[0084] S7, when the first circuit breaker is opened, the main control room sends a closing command to the second circuit breaker through the control system, so that the backup power supply can supply power to the reliable medium-voltage plant bus EMA.

[0085] Specifically, this step includes the following two sub-steps:

[0086] S701: When the first circuit breaker is opened and the opening state lasts for 1s to 2s, the parallel switch cabinet sends a first circuit breaker opening completion signal to the control system.

[0087] S702, when the control system receives the first circuit breaker opening completion signal, the main control room sends a second circuit breaker closing command through the control system.

[0088] Furthermore, after the main control room sends a closing command to the second circuit breaker through the control system, the power supply load is loaded according to a preset loading program.

[0089] In summary, it can be seen from the above description that the above embodiments of the present invention achieve the following technical effects:

[0090] 1. The present invention uses multiple diesel generator sets in parallel as backup power supply, and automatically starts the backup power supply when the preset conditions are met by real-time detection and judgment of the voltage signal of the reliable medium-voltage plant bus EMA, completes the loading of the power supply load and quickly enters a stable operation state. In actual operation, if it is detected that the total power of the load is less than the total power of the unit, and the value is higher than the rated power of a single diesel generator set, a generator set can be intelligently unloaded through the control device, so that the parallel diesel generator sets can operate at a state close to full power, while ensuring the reliability of the unit and improving the flexibility and efficiency of the overall operation.

[0091] 2. The present invention adopts a method of connecting multiple diesel generator sets in parallel as a backup power supply. When a unit fails, especially in extreme cases where it needs to be returned to the factory for overhaul, it can be quickly replaced by borrowing a mobile diesel generator set of corresponding power, which can improve the subsequent operation and maintenance efficiency and unit reliability.

[0092] 3. The present invention uses a parallel control cabinet to determine whether the operating parameters corresponding to the backup power supply meet the preset synchronous conditions, ensuring that the backup power supply can be connected to the power grid at an appropriate time. After the backup power supply is connected in parallel, the main control room can accurately control the opening and closing operations of the circuit breaker to ensure that the backup power supply is smoothly switched to the main power supply state and reduce the power supply interruption time. This method can ensure that when the main generator or off-site power supply fails, the backup power supply is quickly and automatically put into operation, thereby improving the reliability and continuity of the power supply and ensuring stable power supply to critical loads during peak power demand or emergency situations.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0094] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0095] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, which can be embodied in any computer-readable medium for use by an instruction execution system, apparatus or device (such as a computer-based system, a system including a processor or other system that can fetch instructions from an instruction execution system, apparatus or device and execute instructions), or used in combination with these instruction execution systems, apparatuses or devices.

[0096] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0097] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

Claims

1. A control system for a nuclear power plant backup power supply, comprising: The main generator, the main generator circuit breaker, the main transformer, the main power supply outside the plant, the high-voltage plant transformer, the auxiliary power supply outside the plant, the auxiliary transformer, the normal medium-voltage plant bus ESA and the first type of target load, characterized in that it also includes: The first circuit breaker, reliable medium-voltage plant busbar EMA, the second circuit breaker, the second type of target load, the backup power parallel busbar EMC, the third circuit breaker and the backup power supply, The main generator is connected to the main power source outside the factory through the main generator circuit breaker and the main transformer, and is used to supply power to the power system outside the factory; The main generator is connected to the normal medium voltage plant bus ESA through the high voltage plant transformer, and is used to supply power to the normal medium voltage plant bus ESA; The off-site main power supply is connected to the normal medium-voltage plant bus ESA through the main transformer and the high-voltage plant transformer, and is used to supply power to the normal medium-voltage plant bus ESA; The off-site auxiliary power supply is connected to the normal medium-voltage plant bus ESA through the auxiliary transformer, and the off-site auxiliary power supply is used to supply power to the normal medium-voltage plant bus ESA when the off-site main power supply is lost; The backup power parallel bus EMC is connected to the reliable medium-voltage plant bus EMA and the backup power supply through the second circuit breaker and the third circuit breaker, respectively, so that when the main generator, the off-site main power supply and the off-site auxiliary power supply are all lost, the backup power supply supplies power to the backup power parallel bus EMC, and the backup power parallel bus EMC distributes power to the reliable medium-voltage plant bus EMA; The normal medium-voltage plant bus ESA is connected to the first type of target load, and is used to supply power to the first type of target load; the normal medium-voltage plant bus ESA is also connected to the reliable medium-voltage plant bus EMA through the first circuit breaker, and is used to supply power to the reliable medium-voltage plant bus EMA; The reliable medium-voltage plant bus EMA is connected to the second-category target load and is used to supply power to the second-category target load.

2. The system according to claim 1, characterized in that The high-voltage plant transformer is connected between the main generator circuit breaker and the main transformer.

3. The system according to claim 1, characterized in that The backup power source is a diesel generator set.

4. The system according to claim 3, characterized in that Each diesel generator set is provided with a corresponding electrical cabinet, which includes a local control cabinet, a PLC control and synchronization cabinet, a speed regulation and protection cabinet and a voltage transformer cabinet.

5. The system according to any one of claims 1 to 4, characterized in that: When the main generator, the off-site main power supply and the off-site auxiliary power supply are all lost, the starting condition of the backup power supply is: the voltage of the reliable medium-voltage plant bus EMA is lower than 0.8Un, and the voltage duration is greater than or equal to 0.9s.

6. The system according to any one of claims 1 to 4, characterized in that: The input conditions of the backup power supply are: the voltage of the reliable medium-voltage plant bus EMA is within the range of 0 to 0.8 V, and the voltage duration is greater than or equal to 5 seconds.

7. A method for controlling a backup power supply of a nuclear power plant, characterized in that: include: The electrical cabinet detects the voltage of the reliable medium-voltage plant bus EMA, and determines whether the corresponding first voltage signal meets the first preset condition; If the first voltage signal meets the first preset condition, sending the first voltage signal to a main control room through a control system; The main control room sends a backup power supply start signal to the parallel control cabinet through the control system to start the backup power supply; The parallel control cabinet determines whether the operating parameters corresponding to the backup power supply meet the preset synchronization conditions; If the operating parameters reach the preset synchronization conditions, the parallel control cabinet sends a parallel connection signal to the parallel switch cabinet, so that the backup power supply is connected in parallel to the EMC, and the parallel connection signal of the backup power supply is sent to the control system; When the backup power supply is connected in parallel, the main control room sends a trip command to the first circuit breaker through the control system; When the first circuit breaker is opened, the main control room sends a closing command to the second circuit breaker through the control system, so that the backup power supply supplies power to the reliable medium-voltage plant bus EMA.

8. The method according to claim 7, characterized in that The first preset condition is that the voltage value of the first voltage signal is lower than 0.8Un, and the duration of the voltage value is greater than or equal to 0.9s.

9. The method according to claim 7, characterized in that: After starting the backup power supply, the method further comprises: The electrical cabinet detects and determines whether the second voltage signal meets a second preset condition; If the second voltage signal meets the second preset condition, it is determined that the current main generator is tripped, and both the external main power supply and the external auxiliary power supply are lost, and the second voltage signal is sent to the main control room.

10. The method according to claim 9, characterized in that The second preset condition is that the voltage value of the second voltage signal is within the range of 0 to 0.8 V, and the duration of the voltage value is greater than or equal to 5 seconds.

11. The method according to claim 7, characterized in that The operating parameters include voltage, phase and frequency. Judging whether the operating parameters corresponding to the backup power supply meet the preset synchronization conditions includes: Determine whether the voltage, phase and frequency of each diesel generator set in the backup power supply are the same; If the voltage, phase and frequency of each diesel generator set are the same, it is determined that the operating parameters have reached the preset synchronization condition.

12. The method according to claim 7, characterized in that Before judging whether the operating parameters corresponding to each backup power supply have reached the preset synchronization condition, it also includes: Determine whether the voltage of each diesel generator set in the backup power supply has reached the rated voltage, and whether the frequency has reached the rated frequency; If the voltage of each diesel generator set has reached the rated voltage, and the frequency has reached the rated frequency, the electrical cabinet will send a corresponding signal to the control system.

13. The method according to claim 7, characterized in that Also includes: When the first circuit breaker is opened and the opening state lasts for 1s to 2s, the parallel switch cabinet sends a first circuit breaker opening completion signal to the control system; When the control system receives the first circuit breaker opening completion signal, the main control room sends a second circuit breaker closing command through the control system.

14. The method according to any one of claims 7 to 13, characterized in that After the main control room sends a closing command to the second circuit breaker through the control system, the power supply load is loaded according to the preset loading program.

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