Four-active one-hot-standby frequency converter system and control method therefor

Abstract

A four-active one-hot-standby frequency converter system and a control method therefor. The four-active one-hot-standby frequency converter system comprises four main pump branches, a hot-standby branch and a redundant main unit, wherein each of the four main pump branches comprises a busbar, a main pump and a main pump frequency converter, an input end of the main pump frequency converter being connected to the busbar by means of a main pump feeder circuit breaker, and an output end of the main pump frequency converter sequentially being connected to the main pump by means of an outlet circuit breaker and a main pump circuit breaker; the hot-standby branch comprises a hot-standby frequency converter, an input end of the hot-standby frequency converter being connected to any busbar in the four main pump branches by means of a hot-standby frequency converter feeder circuit breaker, and an output end of the hot-standby frequency converter being connected to all of the four main pump branches by means of an interlocking switching apparatus; and the redundant main unit is used for instructing the hot-standby branch to connect to one of the four main pump branches. When any main pump frequency converter is in a faulty state, a common hot-standby frequency converter can be rapidly switched by means of adding a hot-standby branch and newly adding an outlet circuit breaker to a main pump branch.

Description

A frequency converter four-in-one hot standby system and its control method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311222369.2, filed on September 21, 2023, entitled “A Four-purpose and One Hot Standby System of an Inverter and Its Control Method,” and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present invention relates to electrical control technology in the field of nuclear energy, and in particular to a frequency converter four-in-one hot standby system and a control method thereof. Background Art

[0004] In a certain type of reactor in a domestic nuclear power plant, a single reactor is equipped with four reactor coolant pumps (RCP or main pumps). The primary circuit process system diagram of the main pumps is shown in Figure 1.

[0005] The system includes: a first main pump 100, a second main pump 200, a third main pump 300 and a fourth main pump 400, which respectively lift the primary cooling water (agent) into the reactor pressure vessel 700 along the first main loop cold section pipeline 701, the second main loop cold section pipeline 702, the third main loop cold section pipeline 703 and the fourth main loop cold section pipeline 704, and respectively flow out from the first main loop hot section pipeline 705 and the second main loop hot section pipeline 706, and enter the first steam generator 500 and the second steam generator 600 respectively.

[0006] The heat energy generated by the fission of the nuclear fuel in the reactor pressure vessel 700 passes through the first steam generator 500 and the second steam generator 600, and is carried away by the water in the secondary circuits of the first steam generator 500 and the second steam generator 600 through heat exchange. The removed heat is sent to a conventional steam turbine for power generation.

[0007] The first main pump 100 and the second main pump 200 are suspended below the first steam generator 500, and the third main pump 300 and the fourth main pump 400 are suspended below the second steam generator 600. The first steam generator 500 and the second steam generator 600 are arranged symmetrically on either side of the reactor pressure vessel 700. In the reactor coolant system (primary circuit), the four main pumps provide power for the primary circuit water circulation. Because the main pumps are driven by shielded motors, they require a certain speed to ensure that the reaction heat in the reactor pressure vessel 700 is fully and promptly removed and to maintain the continuous and stable nuclear reaction. If the speed of one of the four main pumps drops significantly or stops operating, the primary circuit system will become unstable, and in severe cases, it may lead to a shutdown or even a reactor shutdown.

[0008] Specifically, after the first, second, third, and fourth main pumps 100, 200, 300, and 400 have independently started up, they must operate synchronously (i.e., their speeds rise and fall synchronously) according to the primary process control requirements. Failure of a main pump's power supply (particularly the inverter) for any reason will impact the safe operation of the reactor coolant system. Therefore, improving the operational reliability of the main pump inverters is essential. This impacts both the reliability of the primary electrical system's power supply and the operational reliability of the main pump control system.

[0009] Figure 2 shows the original primary electrical wiring diagram of the four main pumps.

[0010] Among them, the four main pumps are powered by the same power supply method, specifically: the four busbars of the plant power system with a frequency of 50Hz and 10.5kV respectively pass through the main pump feeder circuit breaker, the main pump frequency converter, the main pump group B circuit breaker, and the main pump group A circuit breaker to supply power to the first main pump 100, the second main pump 200, the third main pump 300, and the fourth main pump 400. The rated power supply of each main pump motor is 60Hz and 6.9kV.

[0011] In the normal power supply mode of the main pump, taking a single first main pump 100 as an example, power is supplied to the first main pump 100 through the 50 Hz, 10.5 kV first bus 13, the first main pump feeder circuit breaker 12, the first main pump inverter 11, the first main pump B group circuit breaker 142, and the first main pump A group circuit breaker 141.

[0012] During the unit operation phase, the main pump inverters are powered in groups, and the power supply configuration of the four main pumps is partially supplied simultaneously.

[0013] Each inverter includes a phase-shifting rectifier transformer, an IGBT power unit, a control system and an internal water cooling system.

[0014] To ensure that the main pump can be reliably disconnected from the power supply system in the event of a fault, the main pump group B circuit breakers and main pump group A circuit breakers between each inverter and the connected main pump are connected in series. These circuit breakers are all Class 1E equipment and meet nuclear safety requirements.

[0015] In this primary process system, the functions of the frequency converter include: first, frequency conversion, which converts the 50Hz power supply of the plant power system into the 60Hz working power supply required for the operation of the main pump motor (the rated input frequency of the main pump motor); second, voltage conversion, which converts the 10.5kV power supply of the plant power system into the 6.9kV working power supply required by the main pump motor (the rated input voltage of the main pump motor); third, it realizes the smooth start-up of the main pump and makes the speed adjustment performance more flexible.

[0016] As shown in Figure 2, for the four main pumps and their corresponding main pump inverters, any inverter failure and shutdown, regardless of the cause, will cause the main pumps powered by the faulty inverter to lose drive, directly affecting the safe operation of the reactor coolant system. Therefore, the reliability of the inverter significantly affects the operational reliability of the main pumps and the reactor coolant system.

[0017] During unit startup and operation, the inverter is the sole power source for the main pump motor. The main pump is driven by a 6.9kV, 60Hz shielded motor. Each of the four main pump motors is connected to the 10.5kV, 50Hz plant power system and driven one-to-one by the corresponding inverter. To achieve coordinated control, a control interface is established between the inverter and the nuclear power plant's instrumentation and control system (PLS, also referred to as the redundant host 50 in this document) and the associated circuit breakers (see Figure 3 for the original interface diagram). In Figure 3, the redundant host 50 is connected to the first main pump inverter 11. The first main pump inverter 11 and the redundant host 50 of the instrumentation and control system are connected via a Profibus DP protocol optical fiber. The first main pump feeder circuit breaker 12 provides feedback to the first main pump inverter, indicating the circuit breaker's open and closed position. The first main pump inverter 11 issues open and close commands to the first main pump feeder circuit breaker 12.

[0018] During unit startup, the four VFDs operate as a group after completing their own startup. These four VFDs drive their connected main pumps, which operate simultaneously as a group. If any VFD fails and the fault is not quickly corrected within the specified time, the corresponding main pump motor will lose power, causing the pump to coast and the unit to shut down. Since the reactor's initial full-power operation, VFD failures have occurred repeatedly, including water leaks, power unit failures, communication failures, control system failures, and power failures. These failures have repeatedly caused shutdowns and reactor outages, seriously impacting the safe operation of the nuclear power unit. Therefore, improving the reliability of the main pump power supply and eliminating the potential for unit shutdowns due to VFD failures have become urgent technical challenges.

[0019] Summary of the Invention

[0020] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a four-in-one hot standby frequency converter system and its control method, so as to overcome the problem that when four main pump frequency converters provide one-to-one corresponding power supplies for the four main pumps, once a main pump frequency converter fails, the operating reliability of the entire reactor coolant system will be affected. Based on the existing reactor-type main pump power supply configuration, the main pump power supply is modified to achieve the connection with the original design function, improve the system operation and control flexibility, and improve the operating reliability of the main pump and the operating reliability of this type of nuclear power unit.

[0021] A first aspect of the present invention provides a frequency converter four-in-one hot standby system, comprising:

[0022] Four main pump branches, hot standby branch and redundant host;

[0023] Each of the four main pump branches includes a busbar, a main pump and a main pump frequency converter.

[0024] The input end of the main pump frequency converter is connected to the busbar through the main pump feeder circuit breaker.

[0025] The output end of the main pump frequency converter is connected to the main pump via the outlet circuit breaker and the main pump circuit breaker in sequence;

[0026] The hot standby branch includes a hot standby frequency converter,

[0027] The input end of the hot standby inverter is connected to any one of the busbars in the four main pump branches through the hot standby inverter feeder circuit breaker.

[0028] The output end of the hot standby frequency converter is connected to the four main pump branches respectively through an interlocking switching device;

[0029] The redundant host is used to instruct the hot standby branch to connect to one of the four main pump branches;

[0030] Wherein, the output end of the interlocking switching device is connected between the outlet circuit breaker and the main pump circuit breaker.

[0031] Furthermore, the redundant host is communicatively connected to the hot standby inverter.

[0032] A second aspect of the present invention provides a method for controlling a frequency converter with four functions and one hot standby, using the frequency converter with four functions and one hot standby system as described above, comprising the following steps:

[0033] Step S1: pre-charging the hot standby inverter, and the hot standby inverter enters a hot standby ready state;

[0034] Step S2: the redundant host monitors the main pump frequency converter;

[0035] Step S3: Determine whether the main pump frequency converter is faulty. If the main pump frequency converter is not faulty, execute step S2; if the main pump frequency converter is faulty, execute step S4.

[0036] Step S4: the outlet circuit breaker on the main pump branch with the fault is opened, and the redundant host sends a command to the interlocking switching device to connect the hot standby inverter to the main pump branch with the fault, start the hot standby inverter, phase-lock and track and drive the corresponding main pump;

[0037] Step S5: After the fault is eliminated, the redundant host sends a command to the faulty main pump inverter to resume use, and controls the hot standby inverter to exit use and resume the hot standby ready state.

[0038] Furthermore, in step S4,

[0039] The outlet circuit breaker on the main pump branch with the fault sends a trip signal to the redundant host.

[0040] The time from when the outlet circuit breaker sends a trip signal to when the hot standby frequency converter is connected to the main pump is less than the time the reactor coolant process system allows the main pump speed to drop to 90% of the rated speed.

[0041] Furthermore, the time from when the outlet circuit breaker sends a trip signal to when the hot standby inverter is connected to the main pump is 600ms to 1100ms.

[0042] Furthermore, the step S1 includes:

[0043] Step S11: the hot standby inverter sends a pre-charge preparation signal to the redundant host;

[0044] Step S12: the redundant host issues a pre-charging start instruction to the hot standby inverter, the hot standby inverter issues a closing instruction to the hot standby inverter feeder circuit breaker, the hot standby inverter is connected to the bus and charged, and it is determined whether the hot standby inverter has a fault. If the hot standby inverter has no fault, step S13 is executed. If the hot standby inverter has a fault, the hot standby inverter feeder circuit breaker is disconnected. After the fault is eliminated, step S11 is executed.

[0045] Step S13: the hot standby inverter performs self-test;

[0046] Step S14: the hot standby inverter sends an inverter ready signal to the redundant host, and the redundant host issues a hot standby enable instruction to the hot standby inverter, and the hot standby inverter enters a hot standby ready state.

[0047] Furthermore, in step S12,

[0048] The hot standby inverter determines whether its own DC side bus voltage is greater than 80% of the rated output voltage within 20 seconds after receiving the pre-charging instruction.

[0049] Furthermore, the step S12 includes:

[0050] Step S121: If the DC bus voltage of the hot standby inverter is less than 80% of the rated output voltage and / or the charging time is greater than 20 seconds, it indicates that the hot standby inverter fails in the pre-charging link;

[0051] Step S122: the hot standby inverter sends a fault feedback signal to the redundant host and automatically disconnects the hot standby inverter feeder circuit breaker;

[0052] Step S123: After the fault is eliminated, execute step S11.

[0053] Furthermore, in step S13,

[0054] The self-check includes determining whether there is a fault in the control signal in the control circuit and the auxiliary cooling circuit. If there is no fault in the control signal in the control circuit and the auxiliary cooling circuit, step S14 is executed; if there is a fault in the control signal in the control circuit and the auxiliary cooling circuit, step S122 is executed.

[0055] Furthermore, it is determined whether there is a fault in the current, voltage and pulse signal in the control loop.

[0056] Compared with the prior art, the present invention has the following advantages:

[0057] This invention, based on the current state of process systems and equipment configuration, creatively proposes "four-in-one hot standby" technology. The hot standby inverter has essentially the same performance indicators and control strategy as the main pump inverter, offering flexible equipment operation and reliable power supply, making it easy to implement shared hot standby.

[0058] When one of the multiple main pump inverters fails, it can automatically and quickly switch to the hot standby inverter, and the hot standby inverter will take over the operation of the corresponding main pump. After the faulty inverter is repaired, it can also switch back to the original operation mode, and the hot standby inverter can be switched back to continue to be in the hot standby ready state.

[0059] When it is found that one of the four main pump inverters needs to be shut down for inspection in advance, it can also be replaced by a hot standby inverter through switching. After the equipment is inspected and repaired normally, it can be switched back to the original operating mode.

[0060] The hot standby inverter in this invention can accurately take over from a failed main pump inverter within the time required by the process system, ensuring safe and stable operation of the reactor coolant system. Once operational, the hot standby inverter can be grouped with the other three main pump inverters for control. This highly targeted and feasible approach improves equipment reliability in existing nuclear power plants, enabling online safety isolation of any of the five inverters.

[0061] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application.

[0063] FIG1 is a diagram of a process (reactor coolant) system of four main pumps of a conventional reactor type;

[0064] FIG2 is a primary electrical wiring diagram of the four main pumps of the system shown in FIG1 ;

[0065] FIG3 is a schematic diagram of the original control interface of the main pump frequency converter in the prior art;

[0066] FIG4 is a wiring diagram of a four-in-one hot standby frequency converter system according to an embodiment of the present invention;

[0067] 5 is a diagram of a control interface of a four-in-one hot standby frequency converter system according to an embodiment of the present invention;

[0068] 6 is a diagram of the control interface of the hot standby inverter and the interlocking switching device according to an embodiment of the present invention;

[0069] 7 is a flow chart of a method for controlling a four-in-one hot standby frequency converter according to an embodiment of the present invention;

[0070] FIG8 is a flow chart of the hot standby converter starting up to the hot standby ready state according to an embodiment of the present invention;

[0071] FIG9 is a flow chart of step S14 in FIG8 .

[0072] Reference numerals:

[0073] 100-first main pump;

[0074] 200-second main pump;

[0075] 300-third main pump;

[0076] 400-fourth main pump;

[0077] 500-first steam generator;

[0078] 600-second steam generator;

[0079] 700-reactor pressure vessel;

[0080] 701-first main circuit cold section pipeline;

[0081] 702-second main circuit cold section pipeline;

[0082] 703- Third main circuit cold section pipeline;

[0083] 704-Fourth main circuit cold section pipeline;

[0084] 705-first main circuit hot section pipeline;

[0085] 706-second main circuit hot section pipeline;

[0086] 10-first main pump branch;

[0087] 11-First main pump inverter;

[0088] 12-First main pump feeder circuit breaker;

[0089] 13-first busbar;

[0090] 14-1st main pump circuit breaker;

[0091] 141-1st main pump group A circuit breaker;

[0092] 142-1st main pump group B circuit breaker;

[0093] 15- first outlet circuit breaker;

[0094] 20-Second main pump branch;

[0095] 21- Second main pump inverter;

[0096] 22-Second main pump feeder circuit breaker;

[0097] 23- Second busbar;

[0098] 24-Second main pump circuit breaker;

[0099] 241-Second main pump group A circuit breaker;

[0100] 242-Second main pump group B circuit breaker;

[0101] 25-Second outlet circuit breaker;

[0102] 30-third main pump branch;

[0103] 31- third main pump inverter;

[0104] 32-third main pump feeder circuit breaker;

[0105] 33-third busbar;

[0106] 34-third main pump circuit breaker;

[0107] 341-third main pump group A circuit breaker;

[0108] 342-third main pump group B circuit breaker;

[0109] 35-third outlet circuit breaker;

[0110] 40-fourth main pump branch;

[0111] 41-Fourth main pump inverter;

[0112] 42-fourth main pump feeder circuit breaker;

[0113] 43-fourth busbar;

[0114] 44-fourth main pump circuit breaker;

[0115] 441-4th main pump group A circuit breaker;

[0116] 442-4th main pump group B circuit breaker;

[0117] 45-fourth outlet circuit breaker;

[0118] 50-redundant host;

[0119] 51-Profibus DP protocol optical fiber;

[0120] 60-hot standby branch;

[0121] 61-hot standby inverter;

[0122] 610-Main switch hard wiring;

[0123] 611-first switch hard wiring;

[0124] 612-Second switch hard wiring;

[0125] 613-Third switch hard wiring;

[0126] 614-Fourth switch hard wiring;

[0127] 615-Feeder circuit breaker hard wiring;

[0128] 616-First outlet circuit breaker hard wiring;

[0129] 617-Second outlet circuit breaker hardwired;

[0130] 618-third outlet circuit breaker hardwired;

[0131] 619-4th outlet circuit breaker hardwired;

[0132] 62-hot standby inverter feeder circuit breaker;

[0133] 63- interlocking switching device;

[0134] 631-first switching circuit breaker;

[0135] 632-second switching circuit breaker;

[0136] 633-third switching circuit breaker;

[0137] 634-fourth switching circuit breaker;

[0138] 635-first switching line;

[0139] 636-second switching line;

[0140] 637-third switching line;

[0141] 638-Fourth switching line. DETAILED DESCRIPTION

[0142] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0143] Figure 1 is a process (reactor coolant) system diagram of four main pumps of a traditional reactor type, Figure 2 is an electrical primary wiring diagram of the four main pumps of the system shown in Figure 1, and Figure 3 is a schematic diagram of the original control interface of the main pump inverter in the prior art.

[0144] As shown in Figure 1, the process system of the four main pumps of a traditional reactor type includes: the first main pump 100, the second main pump 200, the third main pump 300 and the fourth main pump 400 respectively lift the primary cooling water (agent) into the reactor pressure vessel 700 along the first main loop cold section pipeline 701, the second main loop cold section pipeline 702, the third main loop cold section pipeline 703 and the fourth main loop cold section pipeline 704, and flow out from the first main loop hot section pipeline 705 and the second main loop hot section pipeline 706, and enter the first steam generator 500 and the second steam generator 600 respectively.

[0145] The heat energy generated by the fission of the nuclear fuel in the reactor pressure vessel 700 passes through the first steam generator 500 and the second steam generator 600, and is carried away by the water in the secondary circuits of the first steam generator 500 and the second steam generator 600 through heat exchange. The removed heat is sent to a conventional steam turbine for power generation.

[0146] The first main pump 100 and the second main pump 200 are suspended below the first steam generator 500, and the third main pump 300 and the fourth main pump 400 are suspended below the second steam generator 600. The first steam generator 500 and the second steam generator 600 are arranged symmetrically on either side of the reactor pressure vessel 700. In the reactor coolant system (primary circuit), the four main pumps provide power for the primary circuit water circulation. Because the main pumps are driven by shielded motors, they require a certain speed to ensure that the reaction heat in the reactor pressure vessel 700 is fully and promptly removed and to maintain the continuous and stable nuclear reaction. If the speed of one of the four main pumps drops significantly or stops operating, the primary circuit system will become unstable, and in severe cases, it may lead to a shutdown or even a reactor shutdown.

[0147] Specifically, after the first, second, third, and fourth main pumps 100, 200, 300, and 400 have independently started up, they must operate synchronously (i.e., their speeds rise and fall synchronously) according to the primary process control requirements. Failure of a main pump's power supply (particularly the inverter) for any reason will impact the safe operation of the reactor coolant system. Therefore, improving the operational reliability of the main pump inverters is essential. This impacts both the reliability of the primary electrical system's power supply and the operational reliability of the main pump control system.

[0148] As shown in Figure 2, the original primary electrical wiring diagram of the four main pumps is given. Among them, the four main pumps are powered by the same power supply method: four buses of the auxiliary power system with a frequency of 50Hz and 10.5kV respectively pass through the main pump feeder circuit breaker, the main pump frequency converter, the main pump group B circuit breaker, and the main pump group A circuit breaker to supply power to the first main pump 100, the second main pump 200, the third main pump 300, and the fourth main pump 400. The rated power supply of each main pump motor is 60Hz and 6.9kV.

[0149] In the normal power supply mode of the main pump, power is supplied to the first main pump 100 through the first busbar 13 of 50Hz, 10.5kV, the first main pump feeder circuit breaker 12, the first main pump frequency converter 11, and the first main pump circuit breaker 14 (the first main pump B group circuit breaker 142, the first main pump A group circuit breaker 141); power is supplied to the second main pump 2 through the second busbar 23 of 50Hz, 10.5kV, the second main pump feeder circuit breaker 22, the second main pump frequency converter 21, and the second main pump circuit breaker 24 (the second main pump B group circuit breaker 242, the second main pump A group circuit breaker 241). 00; the third main pump 300 is powered by the third busbar 33 of 50Hz, 10.5kV, the third main pump feeder circuit breaker 32, the third main pump inverter 31, and the third main pump circuit breaker 34 (third main pump group B circuit breaker 342, third main pump group A circuit breaker 341); the fourth main pump 400 is powered by the fourth busbar 43 of 50Hz, 10.5kV, the fourth main pump feeder circuit breaker 42, the fourth main pump inverter 41, and the fourth main pump circuit breaker 44 (fourth main pump group B circuit breaker 442, fourth main pump group A circuit breaker 441).

[0150] During the unit operation phase, the main pump inverters are powered in groups, and the power supply configuration of the four main pumps is partially supplied simultaneously.

[0151] Each inverter includes a phase-shifting rectifier transformer, an IGBT power unit, a control system and an internal water cooling system.

[0152] As shown in Figure 2, for the four main pumps and their corresponding main pump inverters, any inverter failure and shutdown, regardless of the cause, will cause the main pumps powered by the faulty inverter to lose drive, directly affecting the safe operation of the reactor coolant system. Therefore, the reliability of the inverter significantly affects the operational reliability of the main pumps and the reactor coolant system.

[0153] During unit startup and operation, the inverter is the sole power source for the main pump motor. The main pump is driven by a 6.9kV, 60Hz shielded motor. Each of the four main pump motors is connected to the 10.5kV, 50Hz plant power system and driven one-to-one by the corresponding inverter. To achieve coordinated control, a control interface is established between the inverter and the nuclear power plant's instrumentation and control system (PLS, also referred to as the redundant host 50 in this document) and the associated circuit breakers (see Figure 3 for the original interface diagram). In Figure 3, the redundant host 50 is connected to the first main pump inverter 11. The first main pump inverter 11 and the redundant host 50 of the instrumentation and control system are connected via a Profibus DP protocol optical fiber. The first main pump feeder circuit breaker 12 provides feedback to the first main pump inverter, indicating the circuit breaker's open and closed position. The first main pump inverter 11 issues open and close commands to the first main pump feeder circuit breaker 12.

[0154] Figure 4 is a wiring diagram of a four-in-one hot standby system of a frequency converter in an embodiment of the present invention, which is modified based on the original electrical system in Figure 2 and adds a hot standby branch 60; Figure 5 is a control interface diagram of a four-in-one hot standby system of a frequency converter in an embodiment of the present invention; Figure 6 is a control interface diagram of a hot standby frequency converter 61 and an interlocking switching device 63 in an embodiment of the present invention.

[0155] As shown in FIG. 4 and FIG. 5 , the inverter four-in-one hot standby system of this embodiment includes: four main pump branches, a hot standby branch 60 and a redundant host 50 .

[0156] The four main pump branches include a first main pump branch 10 , a second main pump branch 20 , a third main pump branch 30 and a fourth main pump branch 40 , which are connected to the first main pump 100 , the second main pump 200 , the third main pump 300 and the fourth main pump 400 respectively.

[0157] The first main pump branch 10 includes a first main pump inverter 11. The input end of the first main pump inverter 11 is connected to the first bus 13 through the first main pump feeder circuit breaker 12. The output end of the first main pump inverter 11 is connected to the first main pump 100 through the first outlet circuit breaker 15 and the first main pump circuit breaker 14 in sequence.

[0158] Among them, the first bus 13 is 10.5kV, 50Hz; the functions of the first main pump inverter 11 include: first, frequency conversion, converting the 50Hz power supply of the factory power system into the 60Hz (rated input frequency of the first main pump 100 motor) working power supply required for the operation of the first main pump motor; second, voltage conversion, converting the 10.5kV power supply of the factory power system into the 6.9kV (rated input voltage of the first main pump 100 motor) working power supply required by the first main pump 100 motor; third, achieving smooth start-up of the first main pump 100, and making the speed adjustment performance more flexible.

[0159] The first main pump circuit breaker 14 includes the first main pump A group circuit breaker 141 and the first main pump B group circuit breaker 142. The first main pump A group circuit breaker 141 and the first main pump B group circuit breaker 142 are connected in series. Both are 1E-level equipment, meeting the nuclear safety level requirements, and can ensure that the first main pump 100 can be reliably disconnected from the power supply system in a fault state.

[0160] The second main pump branch 20 adopts the same setting as the first main pump branch 10. The input end of the second main pump inverter 21 is connected to the second bus 23 through the second main pump feeder circuit breaker 22, and the output end of the second main pump inverter 21 is connected to the second main pump 200 through the second outlet circuit breaker 25, the second main pump circuit breaker 24 (the second main pump B group circuit breaker 242 and the second main pump A group circuit breaker 241) in sequence.

[0161] The third main pump branch 30 adopts the same setting as the first main pump branch 10. The input end of the third main pump inverter 31 is connected to the third bus 33 through the third main pump feeder circuit breaker 32, and the output end of the third main pump inverter 31 is connected to the third main pump 300 in sequence through the third outlet circuit breaker 35, the third main pump circuit breaker 34 (the third main pump group B circuit breaker 342 and the third main pump group A circuit breaker 341).

[0162] The fourth main pump branch 40 adopts the same setting as the first main pump branch 10. The input end of the fourth main pump inverter 41 is connected to the fourth bus 43 through the fourth main pump feeder circuit breaker 42, and the output end of the fourth main pump inverter 41 is connected to the fourth main pump 400 through the fourth outlet circuit breaker 45 and the fourth main pump circuit breaker 44 (the fourth main pump B group circuit breaker 442 and the fourth main pump A group circuit breaker 441) in sequence.

[0163] The hot standby branch 60 includes a hot standby inverter 61. The input of the hot standby inverter 61 is connected to any busbar via a hot standby inverter feeder circuit breaker 62. In this embodiment, the hot standby inverter 61 is electrically connected to the first busbar 13. The output of the hot standby inverter 61 is connected to the four main pump branches via an interlocking switching device 63. The output of the interlocking switching device 63 is connected between the outlet circuit breaker of each main pump branch and the circuit breaker of the main pump group B. As shown in FIG6 , the interlocking switching device 63 is internally provided with a first switching circuit breaker 631, a second switching circuit breaker 632, a third switching circuit breaker 633, and a fourth switching circuit breaker 634. The interlocking switching device 63 includes but is not limited to the above components.

[0164] As shown in Figures 5 and 6, the hot standby inverter 61 is controlled by the feeder circuit breaker 62 through the feeder circuit breaker hard wiring 615. The hot standby inverter 61 sends opening and closing instructions to the hot standby inverter feeder circuit breaker 62, and the hot standby inverter feeder circuit breaker 62 feeds back a status signal to the hot standby inverter 61. The hot standby inverter 61 is controlled by the interlocking switching device 63 through the main switching hard wiring 610. The hot standby inverter 61 is respectively controlled by the first switching hard wiring 611, the second switching hard wiring 612, the third switching hard wiring 613 and the fourth switching hard wiring 614. It is associated with the control of the first switching circuit breaker 631, the second switching circuit breaker 632, the third switching circuit breaker 633 and the fourth switching circuit breaker 634; the hot standby inverter 61 is associated with the control of the first outlet circuit breaker 15, the second outlet circuit breaker 25, the third outlet circuit breaker 35 and the fourth outlet circuit breaker 45 through the first outlet circuit breaker hard wiring 616, the second outlet circuit breaker hard wiring 617, the third outlet circuit breaker hard wiring 618 and the fourth outlet circuit breaker hard wiring 619 respectively. The working status of the outlet circuit breakers on each main pump branch is controlled by the main pump inverter corresponding to each branch.

[0165] The control strategy features of the hot standby inverter 61 include mutual switching between the main pump inverters in the four main pump branches and the hot standby inverter 61 without affecting the safe and stable operation of the main pumps and the reactor coolant process system.

[0166] The hot standby inverter 61 has the same electrical structure, electrical parameters, I / O signals, its own control strategy, and the same start-stop process as the main pump inverter. Its functions are basically the same as those of the main pump inverter, and it has the same control functions and corresponding interface specifications. It can independently start, stop, and participate in the process regulation and control of the reactor coolant system to which the main pump belongs. It has the same control characteristics as the main pump inverter, and the control functions are connected.

[0167] As shown in Figure 6, one end of the first switching circuit breaker 631 is connected to the hot standby inverter 61 through the first switching hard wiring 611, and the other end is connected between the first outlet circuit breaker 15 and the first main pump B group circuit breaker 142 through the first switching line 635; one end of the second switching circuit breaker 632 is connected to the hot standby inverter 61 through the second switching hard wiring 612, and the other end is connected between the second outlet circuit breaker 25 and the second main pump B group circuit breaker 242 through the second switching line 636; one end of the third switching circuit breaker 633 is connected to the hot standby inverter 61 through the third switching hard wiring 613, and the other end is connected between the third outlet circuit breaker 35 and the third main pump B group circuit breaker 342 through the third switching line 637; one end of the fourth switching circuit breaker 634 is connected to the hot standby inverter 61 through the fourth switching hard wiring 614, and the other end is connected between the fourth outlet circuit breaker 45 and the fourth main pump B group circuit breaker 442 through the fourth switching line 638.

[0168] The redundant host 50 is used to instruct the hot standby branch 60 to connect to one of the four main pump branches to achieve its own redundant control, and communicate with the hot standby inverter 61. It can communicate with the hot standby inverter 61 through the Profibus DP protocol optical fiber 51 to achieve system control association and redundant control.

[0169] Taking the failure of the first main pump inverter 11 on the first main pump branch 10 as an example, before the failure, the first main pump inverter 11 was operating in a group with the second main pump inverter 21, the third main pump inverter 31, and the fourth main pump inverter 41. Once the first main pump inverter 11 fails, the first outlet circuit breaker 15 between the first main pump inverter 11 and the first main pump 100 automatically opens, triggering the redundant host 50 to issue a command to drive the interlocking switching device 63 to operate. The hot standby inverter 61 starts and replaces the failed first main pump inverter 11. The hot standby inverter 61 phase-locks and tracks the first main pump 100 motor. After the phase-lock tracking is successful, it takes over the first main pump 100 motor and supplies power to the first main pump 100 motor. In order to avoid the speed of the first main pump 100 driven by the faulty first main pump inverter 11 from dropping too much (the maximum allowable speed of the first main pump 100 is 90% of the rated speed), thereby causing unstable operation of the reactor coolant system, the switching process from the automatic disconnection of the first outlet circuit breaker 15 to the successful phase-locked tracking of the first main pump 100 motor by the hot standby inverter 61 and taking over the first main pump 100 motor should be completed within the time specified by the process requirements (generally between 600ms-1100ms).

[0170] After the first main pump inverter 11 switches to the hot standby inverter 61, the hot standby inverter 61 takes over the first main pump 100 motor and forms a new group with the second main pump inverter 21, the third main pump inverter 31 and the fourth main pump inverter 41, namely the hot standby inverter 61, the second main pump inverter 21, the third main pump inverter 31 and the fourth main pump inverter 41, which drive the first main pump 100, the second main pump 200, the third main pump 300 and the fourth main pump 400 respectively. At this time, the first main pump inverter 11 exits operation.

[0171] After the fault in the first master pump inverter 11 is eliminated, the original group operation can be resumed. On the control interface, the operator selects the switchover option. The operator issues a switchover command, which in turn sends a control command through the redundant host 50 to cause the hot standby inverter 61 to exit. The hot standby inverter 61 instructs the first switching circuit breaker 631 in the interlocking switching device 63 to open. The redundant host 50 then issues a control command to the first master pump inverter 11 to instruct the first outlet circuit breaker 15 to close. The first master pump inverter 11 then resumes phase-locked tracking and power supply operations for the corresponding first master pump 100.

[0172] In summary, the redundant host 50 performs logical judgment and subsequent control on the acquired fault, and drives the interlocking switching device 63 to realize the hot standby of the hot standby inverter 61.

[0173] FIG7 is a flow chart of a method for controlling a four-in-one hot standby frequency converter according to an embodiment of the present invention, and is a flow chart of a newly added hot standby branch 60 entering into a fault switching and stopping state.

[0174] As shown in FIG7 , the inverter four-in-one hot standby control method adopts the inverter four-in-one hot standby system described above, and includes the following steps:

[0175] Step S1: pre-charging the hot standby inverter 61, and the hot standby inverter 61 enters a hot standby ready state;

[0176] Step S2: the redundant host 50 monitors the main pump frequency converter;

[0177] Step S3: Determine whether the main pump frequency converter is faulty. If the main pump frequency converter is not faulty, execute step S2. If the main pump frequency converter is faulty, execute step S4.

[0178] Step S4: The outlet circuit breaker on the failed main pump branch is opened, and the redundant host 50 issues a command to the interlocking switching device 63 to connect the hot standby inverter 61 to the failed main pump branch, start the hot standby inverter 61, phase-lock and track and drive the corresponding main pump;

[0179] Step S5: After the fault is eliminated, the redundant host 50 issues a command to the faulty main pump inverter to resume use, and controls the hot standby inverter 61 to exit use and resume the hot standby ready state.

[0180] The following describes each step in detail.

[0181] Step S1: pre-charge the hot standby inverter 61, and the hot standby inverter 61 enters a hot standby ready state.

[0182] FIG8 is a flow chart showing how the hot standby converter 61 is started to a hot standby ready state in an embodiment of the present invention. This is a hot standby process, ie, the redundant host 50 instructs the hot standby converter 61 to start to a hot standby ready state.

[0183] As shown in FIG8 , step S1 includes the following steps:

[0184] Step S11: the hot standby inverter 61 sends a pre-charge preparation signal to the redundant host 50;

[0185] Step S12: The redundant host 50 issues a pre-charging start instruction to the hot standby inverter 61. The hot standby inverter 61 issues a closing instruction to the hot standby inverter feeder circuit breaker 62. The hot standby inverter 61 is connected to the bus and charging is performed. It is determined whether the hot standby inverter 61 has a fault. If the hot standby inverter 61 has no fault, step S13 is executed. If the hot standby inverter 61 has a fault, the hot standby inverter feeder circuit breaker 62 is opened. After the fault is eliminated, step S11 is executed.

[0186] Step S13: The hot standby inverter 61 performs a self-test;

[0187] Step S14: the hot standby inverter 61 sends an inverter ready signal to the redundant host 50, and the redundant host 50 issues a hot standby enable instruction to the hot standby inverter 61, and the hot standby inverter 61 enters a hot standby ready state.

[0188] Specifically, in step S12, the hot standby inverter feeder circuit breaker 62 is closed (the medium voltage power source supplies power to the hot standby inverter 61 through the hot standby inverter feeder circuit breaker 62 and the pre-charge resistor). Voltage is output from the DC bus inside the hot standby inverter 61. The hot standby inverter 61 transmits a pre-charging signal to the redundant host 50.

[0189] Within 20 seconds of receiving the precharge command, the redundant host 50 determines whether the DC bus voltage of the hot standby inverter 61 is greater than 80% of the rated output voltage. The hot standby inverter 61 consists of two components: a rectifier (AC-DC) and an inverter (DC-AC). The rectifier outputs the rectified voltage to the DC bus. Once the DC bus voltage exceeds 80% of the rated output voltage, precharge is essentially complete and the rectifier is functioning normally. At this point, the precharge switch of the hot standby inverter 61 closes (bypassing the precharge resistor), applying full voltage to the input of the phase-shifting rectifier transformer within the hot standby inverter 61. This significantly reduces the transformer's magnetizing inrush current (this is the purpose of the precharge circuit).

[0190] Step S12 includes the following steps:

[0191] Step S121: If the DC bus voltage of the hot standby inverter 61 is less than 80% of the rated output voltage and / or the charging time is greater than 20 seconds, it indicates that the hot standby inverter 61 has failed in the pre-charging link;

[0192] Step S122: the hot standby inverter 61 sends a fault feedback signal to the redundant host 50 and automatically disconnects the hot standby inverter feeder circuit breaker 62;

[0193] Step S123: After the fault is eliminated, execute step S11.

[0194] In step S121, if it is determined that the DC bus voltage of the hot standby inverter 61 is less than 80% of the rated output voltage there, it indicates that the pre-charging within 20 seconds cannot achieve the expected effect, and the charging time is further determined to be greater than 20 seconds.

[0195] Specifically, in step S13, the hot standby inverter 61 performs a self-test, including determining whether there are faults in the control signals in the control circuit and the auxiliary cooling circuit. Specifically, the self-test determines whether there are faults in the current, voltage, and pulse signals in the control circuits. If there are no faults in the control signals in the control circuit and the auxiliary cooling circuit, the hot standby inverter 61 passes the self-test, and step S14 is executed, where the hot standby inverter 61 transmits the hot standby ready status to the redundant host 50. If there are faults in the control signals in the control circuit and the auxiliary cooling circuit, step S122 is executed. Once the fault is resolved, step S11 is executed.

[0196] FIG9 is a flow chart of step S14 in FIG8 .

[0197] As shown in FIG9 , step S14 includes the following steps:

[0198] Step S141: the hot standby inverter 61 sends an inverter ready signal to the redundant host 50;

[0199] Step S142: The redundant host 50 issues a hot standby enable instruction to the hot standby inverter 61, and determines whether the hot standby inverter 61 has received the hot standby enable instruction. If the hot standby inverter 61 has received the hot standby enable instruction, step S143 is executed. If the hot standby inverter 61 has not received the hot standby enable instruction, step S142 is continued.

[0200] Step S143: determining whether the redundant host 50 has lost its standby enable signal; if so, executing step S144; if not, executing step S142;

[0201] Step S144: the hot standby inverter 61 enters the hot standby ready fault state, exits the hot standby state, and executes step S2.

[0202] Specifically, in step S143 , the redundant host 50 loses the standby enable signal, that is, the redundant host 50 no longer sends the hot standby enable signal.

[0203] Figures 7, 8 and 9 are the startup links before the hot standby inverter 61 enters the public hot standby state. They incorporate design functions such as connecting with the original design functions and realizing the original operation control of the main pump, and optimize the operation control of the main pump to improve the flexibility of system operation control.

[0204] Step S2: The redundant host 50 monitors the main pump inverter.

[0205] The redundant host 50 monitors the first main pump frequency converter 11 , the second main pump frequency converter 21 , the third main pump frequency converter 31 and the fourth main pump frequency converter 41 .

[0206] Step S3: Determine whether the main pump frequency converter is faulty. If the main pump frequency converter is not faulty, execute step S2; if the main pump frequency converter is faulty, execute step S4.

[0207] During the monitoring process, determine whether the first main pump inverter 11, the second main pump inverter 21, the third main pump inverter 31 and the fourth main pump inverter 41 are faulty. If none of the four main pump inverters are faulty, execute step S2 and continue monitoring. If one of the four main pump inverters is faulty, execute step S4.

[0208] Step S4: The outlet circuit breaker on the faulty main pump branch is opened, and the redundant host 50 sends a command to the interlocking switching device 63 to connect the hot standby inverter 61 to the faulty main pump branch, start the hot standby inverter 61, phase-lock tracking and drive the corresponding main pump.

[0209] Specifically, if the first main pump inverter 11 of the first main pump branch 10 fails, the redundant host 50 instructs the first main pump feeder circuit breaker 12 connected to the first main pump branch 10 to open, and the interlocking switching device 63 connects the hot standby inverter 61 and the first main pump B group circuit breaker 142 on the first main pump branch 10 (in the electrical circuit, the hot standby inverter 61 is connected to the first main pump 100 motor through the interlocking switching device 63, and the faulty first main pump inverter 11 exits through the first outlet circuit breaker 15 after opening).

[0210] If the second main pump inverter 21 of the second main pump branch 20 fails, the redundant host 50 instructs the second main pump feeder circuit breaker 22 connected to the second main pump branch 20 to open, and the interlocking switching device 63 connects the hot standby inverter 61 and the second main pump group B circuit breaker 242 on the second main pump branch 20.

[0211] If the third main pump inverter 31 of the third main pump branch 30 fails, the redundant host 50 instructs the third main pump feeder circuit breaker 32 connected to the third main pump branch 30 to open, and the interlocking switching device 63 connects the hot standby inverter 61 and the third main pump group B circuit breaker 342 on the third main pump branch 30.

[0212] If the fourth main pump inverter 41 of the fourth main pump branch 40 fails, the redundant host 50 instructs the fourth main pump feeder circuit breaker 42 connected to the fourth main pump branch 40 to open, and the interlocking switching device 63 connects the hot standby inverter 61 and the fourth main pump group B circuit breaker 442 on the fourth main pump branch 40.

[0213] The hot standby inverter 61 starts and phase-locks to the main pump motor (residual voltage) on the faulty main pump branch. Once phase-locked tracking is normal, the hot standby inverter 61 outputs 60Hz three-phase AC power to drive the corresponding main pump motor to continue operation. This completes the process of hot standby inverter 61 taking over from the faulty main pump inverter.

[0214] Step S5: After the fault is eliminated, the redundant host 50 issues a command to the faulty main pump inverter to resume use, and controls the hot standby inverter 61 to exit use and resume the hot standby ready state.

[0215] Specifically, after the fault is eliminated, the redundant host 50 instructs the hot standby inverter 61 to change the speed setting, and the hot standby inverter 61 participates in the group speed regulation operation. The redundant host 50 instructs the speed setting to be 0%, that is, the instruction speed is 0, and the corresponding main pump does not need to output. The hot standby inverter 61 stops and returns to the hot standby ready state. The outlet circuit breaker of the main pump branch is closed, the main pump inverter is connected to the main pump, and the main pump inverter resumes the phase-locked tracking and power supply work of the corresponding main pump.

[0216] Figure 7 illustrates the entire process from the moment the hot standby inverter 61 receives a command from the redundant host 50 to take over control of one of the four main pump inverters after a fault occurs, until the fault is resolved and the hot standby inverter 61 exits operation. This process must match the control strategy before the modification. The key to a successful switchover is that the hot standby inverter 61 can ensure that the entire switchover time, from the moment the redundant host 50 issues the switchover command to the moment it successfully takes over the main pump of the failed main pump branch, falls within the time specified by the process (generally between 600ms and 1100ms). This requires the modified equipment to possess high reliability, precise switching logic, and coordinated control strategy optimization for the smooth operation of the process system.

[0217] In summary, the inverter four-in-one hot standby system and its control method disclosed in the present invention achieve the following invention objectives:

[0218] First, optimize the configuration of the main pump power supply structure. The hot standby frequency converter 61 can correctly replace the failed main pump frequency converter and take over its corresponding main pump within the time required by the process system, thereby achieving safe and stable operation of the reactor coolant system. A single main pump is independently powered by the main pump frequency converter. However, the main pump frequency converter has many components such as its own power supply system, phase-shifting rectifier transformer, IGBT power unit, control system, internal water cooling system, and communication part. There are many factors that can easily cause the failure of the main pump frequency converter. Once the main pump frequency converter fails and stops supplying power, the corresponding main pump will lose power. The present invention proposes a solution of "adding a hot standby frequency converter 61 as a hot standby for the four main pump frequency converters", and realizes that under the condition of a main pump frequency converter failure, the newly added hot standby frequency converter 61 can quickly and automatically start and take over the corresponding main pump through the control strategy within the response time specified by the safety requirements of the reactor coolant system.

[0219] Second, the present invention adds a hot standby frequency converter 61, an interlocking switching device 63, and related outlet circuit breakers and other primary equipment to the primary electrical circuit, but these devices alone are not enough, and it is also necessary to provide supporting control methods related to these devices, as well as optimization and improvement of the control methods for the original four main pump frequency converters. The present invention combines the original process control requirements and frequency converter control strategy requirements of the reactor coolant system to optimize the control method strategy. For example, the original only four main pump frequency converters were operated in group control, and after the transformation, five group control methods need to be considered (i.e., the original one group control, plus four additional group control methods after the hot standby frequency converter 61 is switched in after one of the four main pump frequency converters fails, and the corresponding changes in the control strategy of the monitoring interface, etc.).

[0220] Third, the reliability of the frequency converter itself is improved. The device operation mode of the present invention is flexible and can realize public hot standby more conveniently.

[0221] If one of the four main pump inverters fails, it automatically and quickly switches to the hot standby inverter 61, which then takes over operation of the corresponding main pump. Once the failed main pump inverter is repaired, it can be switched back to its original operating mode, and the hot standby inverter 61 can be switched back to hot standby.

[0222] If one of the four main pump inverters needs to be shut down for inspection, it can be replaced with the hot standby inverter 61. After the equipment is inspected and repaired, it can be switched back to the original operating mode.

[0223] Fourth, the present invention perfectly combines the current status of process systems and equipment configurations, and creatively proposes the "four-in-one hot standby" technology. After the implementation of the present invention, any one of the five frequency converters with four in-one hot standby can achieve online safety isolation. Specifically, it mainly starts from improving the health level of the current equipment, and optimizes the design functions throughout the life cycle by optimizing operation, inspection and testing, operation and maintenance management, etc., to achieve the addition of a hot standby frequency converter 61 as a hot standby for the four main pump frequency converters. Of course, when conditions are right, using a more reliable frequency converter to update and replace is also one of the options to further improve the reliability of frequency converter operation.

[0224] Fifth, the present invention is highly targeted and feasible for improving equipment reliability in nuclear power plants that have already been built.

[0225] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A frequency converter four-in-one hot standby system, characterized in that: include: Four main pump branches, hot standby branches and redundant host; Each of the four main pump branches includes a bus, a main pump and a main pump frequency converter. The input end of the main pump inverter is connected to the busbar through the main pump feeder circuit breaker. The output end of the main pump frequency converter is connected to the main pump via the outlet circuit breaker and the main pump circuit breaker in sequence; The hot standby branch includes a hot standby frequency converter, The input end of the hot standby inverter is connected to any busbar of the four main pump branches through the hot standby inverter feeder circuit breaker. The output end of the hot standby frequency converter is respectively connected to the four main pump branches through an interlocking switching device; The redundant host is used to instruct the hot standby branch to be connected to one of the four main pump branches; Wherein, the output end of the interlocking switching device is connected between the outlet circuit breaker and the main pump circuit breaker.

2. The inverter four-in-one hot standby system according to claim 1, characterized in that: The redundant host is communicatively connected to the hot standby inverter.

3. A method for controlling a frequency converter with four functions and one hot standby, characterized in that: The inverter four-in-one hot standby system according to any one of claims 1 to 2 comprises the following steps: Step S1: pre-charge the hot standby inverter, and the hot standby inverter enters hot standby mode. emotional state; Step S2: the redundant host monitors the main pump frequency converter; Step S3: Determine whether the main pump frequency converter is faulty. If the main pump frequency converter is not faulty, execute step S2; if the main pump frequency converter is faulty, execute step S4; Step S4: the outlet circuit breaker on the main pump branch with the fault is opened, the redundant host sends a command to the interlocking switching device to connect the hot standby inverter with the main pump branch with the fault, start the hot standby inverter, phase-lock and track and drive the corresponding main pump; Step S5: After the fault is eliminated, the redundant host sends a command to the failed main pump inverter to resume use, and controls the hot standby inverter to exit use and resume the hot standby ready state.

4. The inverter four-in-one hot standby control method according to claim 3, characterized in that: In step S4, The outlet circuit breaker on the main pump branch where the fault occurs sends a trip signal to the redundant host. The time from when the outlet circuit breaker sends a trip signal to when the hot standby frequency converter is connected to the main pump is less than the time the reactor coolant process system allows the main pump speed to drop to 90% of the rated speed.

5. The inverter four-in-one hot standby control method according to claim 4, characterized in that: The time from when the outlet circuit breaker sends a trip signal to when the hot standby inverter is connected to the main pump is 600ms to 1100ms.

6. The inverter four-in-one hot standby control method according to claim 3, characterized in that: The step S1 comprises: Step S11: the hot standby inverter sends a pre-charging preparation signal to the redundant host; Step S12: the redundant host sends a pre-charging start instruction to the hot standby inverter, the hot standby inverter sends a closing instruction to the hot standby inverter feeder circuit breaker, the hot standby inverter is connected to the bus and charged, and it is determined whether the hot standby inverter fails. If the hot standby inverter does not fail, step S13 is executed. If the hot standby inverter fails, the hot standby inverter feeder circuit breaker is disconnected, and after the fault is eliminated, step S11 is executed; Step S13: the hot standby inverter performs self-test; Step S14: the hot standby inverter sends an inverter ready signal to the redundant host, the redundant host issues a hot standby enable instruction to the hot standby inverter, and the hot standby inverter enters a hot standby ready state.

7. The inverter four-in-one hot standby control method according to claim 6, characterized in that: In step S12, The hot standby inverter determines whether its own DC side bus voltage is greater than 80% of the rated output voltage within 20 seconds after receiving the pre-charging instruction.

8. The inverter four-in-one hot standby control method according to claim 7, characterized in that: The step S12 comprises: Step S121: If the DC bus voltage of the hot standby inverter is less than 80% of the rated output voltage there and / or the charging time is greater than 20s, it indicates that the hot standby inverter fails in the pre-charging link; Step S122: the hot standby inverter sends a fault feedback signal to the redundant host and automatically disconnects the feeder circuit breaker of the hot standby inverter; Step S123: After the fault is eliminated, execute step S11.

9. The inverter four-in-one hot standby control method according to claim 8, characterized in that: In step S13, The self-check includes determining whether there is a fault in the control signal in the control circuit and the auxiliary cooling circuit. If there is no fault in the control signal in the control circuit and the auxiliary cooling circuit, execute step S14; if there is a fault in the control signal in the control circuit and the auxiliary cooling circuit, execute step S122.

10. The inverter four-in-one hot standby control method according to claim 9, characterized in that: Determine whether there is a fault in the current, voltage and pulse signal in the control loop.

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