Back-switching control system and method for multiple operating variable frequency drives and one standby variable frequency drive

Abstract

Provided in the present invention are a back-switching control system and method for multiple operating variable frequency drives and one standby variable frequency drive. The system comprises: multiple operating variable frequency drives, wherein each operating variable frequency drive is connected to a corresponding main pump electric motor by means of a corresponding outlet circuit breaker, so as to drive the corresponding main pump electric motor; a standby variable frequency drive, which is used for replacing one operating variable frequency drive to operate; and a plant control system. A control system for each operating variable frequency drive is configured to: receive, in a state where the standby variable frequency drive replaces the operating variable frequency drive to operate, a back-switching preparation instruction sent by the plant control system; release the state of electrical interlocking between an outlet circuit breaker for the standby variable frequency drive and an outlet circuit breaker for the operating variable frequency drive, which is replaced to operate; control the outlet circuit breaker for said operating variable frequency drive to switch from a turned-off state to a turned-on state; receive an operation signal of the corresponding main pump electric motor, and control said operating variable frequency drive to execute a tracking phase-locking operation; and send a back-switching enable preparation ready signal to the plant control system.

Description

A multi-operation and one-standby inverter switchback control system and method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202410157275.X filed on February 4, 2024, entitled “A multi-operation and one-standby inverter reversal control system and method,” and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present invention mainly relates to the field of power electronic technology frequency converters, and in particular to a switchback control system and method for multiple-operation-one-standby frequency converters. Background Art

[0004] The reactor coolant system of a certain nuclear power plant is equipped with four reactor coolant pumps (referred to as "main pumps"), each driven by a high-voltage inverter. The four main pumps and their corresponding inverters are centrally controlled by the plant control system (PLS). Except for individual main pump start and stop operations, the four main pumps and their corresponding inverters operate as a group during nuclear power unit operation.

[0005] Reactor coolant system processes place high demands on the reliability of the main pumps. Failure of a single main pump can lead to reactor and unit failure. Some existing high-voltage inverters provide a single backup high-voltage inverter for each of the four active main pumps (a "four-in-operation, one-backup" or "four-backup, one-backup" approach). Therefore, if any of the four active inverters fails while the four main pumps are operating, the backup inverter must be quickly switched into operation, shutting down the faulty inverter and adjusting the control grouping of the original main pumps (including the inverter) to the new one.

[0006] After the fault is resolved, the faulty inverter can be put back into operation to replace the public backup inverter (the power plant control system will then form a new group). At this point, the public backup inverter will need to exit operation and resume its role as the public backup. This process is called inverter resetting.

[0007] Given this, switching back after a faulty inverter is repaired becomes extremely important. Considering that in some cases, the operating inverter, standby inverter, and plant control system (PLS) come from different manufacturers and their respective control systems are incompatible, switching back after a faulty inverter is repaired involves the following technical issues:

[0008] (a) The logic control and strategy of the inverter switching back are imperfect.

[0009] (b) The transmission path of the inverter switching back command (i.e. the source of the switching command received by the relevant inverter) is whether it comes from a specific inverter or from a unified power plant control system.

[0010] (c) According to the process requirements of the reactor coolant system, the switching back between inverters should be completed within the specified time (for example, approximately between 0.5 seconds and 1.5 seconds).

[0011] (d) Communication between different control systems, involving power plant control systems and frequency converters (different manufacturers equip their frequency converters with different redundant control systems).

[0012] In the nuclear power and electricity generation fields, the applicant has not seen mature applications of inverter reversal technology in high-voltage inverter control. Furthermore, regarding the aforementioned inverter reversal issue, the inventor has reviewed relevant literature and publicly available patents and other intellectual property information but has found no relevant technology.

[0013] Summary of the Invention

[0014] In response to the problems existing in the prior art, the present invention provides a multi-operation and one-standby inverter switchback control system and method, which realizes efficient and safe switchback operations between the standby inverter and multiple operating inverters, thereby improving the overall operating stability of the system in which the multi-operation and one-standby inverter are located.

[0015] The first aspect of the present invention provides a multi-operation and one-standby frequency converter reversal control system, comprising: a plurality of frequency converters in operation, each frequency converter in operation being connected to a corresponding main pump motor via a corresponding outlet circuit breaker to drive the corresponding main pump motor; each frequency converter in operation comprising a corresponding control system; a standby frequency converter comprising a corresponding control system; the standby frequency converter being used to replace the operation of one of the plurality of frequency converters in operation to drive the corresponding main pump motor; a power plant control system; the control system of each frequency converter in operation being configured to: receive a reversal preparation instruction issued by the power plant control system when the standby frequency converter replaces the operation of the frequency converter in operation; and release the output of the standby frequency converter according to the reversal preparation instruction. The electrical locking state between the outlet circuit breaker of the standby inverter and the outlet circuit breaker of the replaced inverter enables the outlet circuit breaker of the standby inverter and the outlet circuit breaker of the replaced inverter to be closed at the same time; controls the outlet circuit breaker of the replaced inverter to switch from the open state to the closed state; receives the operation signal of the main pump motor driven by the replaced inverter, and controls the replaced inverter to perform the tracking phase-locked operation according to the instruction requirements; after the tracking phase-locked operation is completed, sends a re-switching enable ready signal to the power plant control system; executes the re-switching function according to the control instruction, executes the re-switching failure recovery function when the re-switching fails, and feeds back the result of executing the re-switching instruction.

[0016] Preferably, the power plant control system is configured to: issue a switchback instruction to the control system of the standby converter based on the switchback enable ready signal.

[0017] Preferably, the control system of the standby inverter is configured to: issue a blocking output instruction based on the switchback instruction, so that the standby inverter no longer outputs torque to stop driving the main pump motor connected to the standby inverter; issue a blocking output operation indication signal to the control system of the operating inverter replaced by the standby inverter; the control system of the operating inverter replaced by the standby inverter is also configured to: after receiving the blocking output operation indication signal, start outputting torque according to the result of tracking the phase-locked operation to drive the corresponding main pump motor.

[0018] Preferably, the control system for switching back multiple frequency converters to a standby frequency converter also includes an interlocking switching device; the interlocking switching device includes at least a number of output circuit breakers, the same number as the frequency converters in operation, serving as output circuit breakers for the standby frequency converters; the standby frequency converter is respectively connected to the main pump motors corresponding to the multiple frequency converters in operation through the multiple output circuit breakers of the interlocking switching device.

[0019] Preferably, the control system of the operating frequency converter and the control system of the standby frequency converter are connected via a hard-wired line to transmit the blocking output operation instruction signal; the hard-wired line includes a communication line.

[0020] Preferably, the operating signal of the main pump motor includes speed, torque, drive voltage, drive current and phase signal.

[0021] Preferably, the control system of the standby frequency converter is further configured as follows:

[0022] After issuing a blocking output instruction and a blocking output operation indication signal, the tracking phase-locked state of the main pump motor previously driven by the standby frequency converter is maintained; the control system of the operating frequency converter replaced by the standby frequency converter is also configured to: after starting to output torque to drive the corresponding main pump motor, delay for a first time interval to determine whether the drive signal currently output by the operating frequency converter meets the preset drive conditions; if it meets the preset drive conditions, a switchback success signal is sent to the power plant control system.

[0023] Preferably, the control system of the standby inverter is further configured to: issue a disconnect instruction for the output circuit breaker of the standby inverter based on the received switchback success signal; the control system of the operating inverter replaced by the standby inverter is further configured to: restore the electrical locking state between the output circuit breaker of the standby inverter and the output circuit breaker of the replaced operating inverter, so that the output circuit breaker of the standby inverter and the output circuit breaker of the replaced operating inverter cannot be closed at the same time.

[0024] Preferably, the control system of the operating frequency converter that is replaced by the standby frequency converter is also configured to: if it is determined that the driving signal currently output by the operating frequency converter does not meet the preset driving conditions, instruct the operating frequency converter to disconnect its output circuit breaker; send a retry failure signal to the power plant control system; restore the electrical locking state between the output circuit breaker of the standby frequency converter and the output circuit breaker of the replaced operating frequency converter, so that the output circuit breaker of the standby frequency converter and the output circuit breaker of the replaced operating frequency converter cannot be closed at the same time; the control system of the standby frequency converter is also configured to: based on the retry failure signal, send a cancel block output operation instruction to make the standby frequency converter output torque again to continue to drive the main pump motor connected to the standby frequency converter.

[0025] Preferably, the control system of the standby inverter is also configured to: instruct the re-output of torque to continue driving the main pump motor connected to the standby inverter, and then enter the link of judging whether the drive signal currently output by the standby inverter meets the preset drive conditions; if it meets the preset drive conditions, an indication signal corresponding to the failure of the reversal and the continued operation of the standby inverter is sent to the power plant control system.

[0026] Preferably, the control system of the standby inverter is further configured to send an indication signal corresponding to a switchback failure and a system fault to the power plant control system if it is determined that the drive signal currently output by the standby inverter does not meet the preset drive conditions.

[0027] Preferably, each operating frequency converter is connected to the power supply through a corresponding imported circuit breaker, and the control system of each operating frequency converter is also configured to: when the standby frequency converter replaces the operating frequency converter, before receiving the switchback preparation instruction issued by the power plant control system, perform the frequency converter pre-charging operation by instructing the imported circuit breaker to close; after the pre-charging operation is completed, send a pre-charging completion signal to the power plant control system.

[0028] Preferably, the main pump motor is used for nuclear reactor coolant delivery.

[0029] Preferably, an inlet circuit breaker of the main pump motor is also provided between the outlet circuit breaker of the operating frequency converter and the main pump motor.

[0030] The second aspect of the present application also provides a method for switching back control of multiple operating and one standby frequency converters, wherein the multiple operating and one standby frequency converters include multiple operating frequency converters and one standby frequency converter; the method includes: each operating frequency converter receives a switching back preparation instruction issued by the power plant control system when the standby frequency converter replaces the operating frequency converter; according to the switching back preparation instruction, the electrical locking state between the output circuit breaker of the standby frequency converter and the output circuit breaker of the replaced operating frequency converter is released, so that the output circuit breaker of the standby frequency converter and the output circuit breaker of the replaced operating frequency converter can be closed at the same time; the output circuit breaker of the replaced operating frequency converter is controlled to switch from an open state to a closed state; the operating signal of the main pump motor driven by the replaced operating frequency converter is received, and the replaced operating frequency converter is controlled to perform a tracking phase-locked operation according to the instruction requirements; after the tracking phase-locked operation is completed, the replaced operating frequency converter sends a switching back enable ready signal to the power plant control system.

[0031] Compared with the prior art, the present invention has the following advantages: the technical solution of the present application can realize the smooth, safe and efficient switching back operation process when switching back to the operating inverter replaced by the standby inverter after the standby inverter replaces the operating inverter, and has the function of recovering the switching failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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.

[0033] FIG1 is a schematic diagram of the electrical principle of a multi-operation-one-standby frequency converter according to the present invention.

[0034] 2 is a schematic diagram of the connection of the control interface of the standby inverter of the multi-operation-one-standby main pump inverter according to the present invention.

[0035] FIG3 is a flow chart of a switchback control method for a multi-operation-one-standby inverter according to the present invention. DETAILED DESCRIPTION

[0036] 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.

[0037] In response to several technical issues involved in the re-switching of a faulty inverter after repair, the inventors proposed a multi-operation and one-standby inverter re-switching control system and developed a multi-operation and one-standby high-voltage inverter re-switching control method, which realized the re-switching of a faulty inverter in the inverter group after repair.

[0038] It should be noted that the present application is not limited to high-voltage inverters, but can also be applied to low-voltage inverters (ie, inverters with a driving voltage less than or equal to 380 volts).

[0039] The multi-operation-one-standby inverter switchback control system and method of the present invention specifically include:

[0040] (a) The switchback logic and process after the faulty inverter is repaired are developed.

[0041] (b) By adding I / O (input / output) signals and interfaces, mutual communication between the control systems of different frequency converters (e.g., control systems with redundancy, or simply referred to as redundant control systems) and the power plant control system is achieved, thereby improving the operating strategy of the frequency converter control system.

[0042] (c) Hard wiring is set up between the redundant control systems of different inverters.

[0043] (d) The master control position of the standby inverter in the switchback process is established, and the transmission path of the switchback instruction (i.e. the source of the switchback instruction received by the inverter) is clarified.

[0044] (e) Based on the process requirements of the reactor coolant system, the criteria for successful cutback were determined, and the cutback time limit and the "cutback failure" recovery control strategy were formulated.

[0045] The "multiple in operation, one standby" concept in this invention can be understood as "multiple high-voltage inverters in operation, with one high-voltage inverter in common hot standby." This principle can be extended based on process requirements. In the following embodiments, the invention is described in detail using a scenario where four high-voltage inverters are in operation and one high-voltage inverter is in common hot standby (four in operation, one standby). For scenarios where two, three, or more than four inverters are in operation, the switching principles are the same or similar to those described herein.

[0046] For the convenience of illustration and explanation, the following conventions are made:

[0047] (a) For equipment running with multiple high-voltage inverters, take one high-voltage inverter (VFD0) as a public hot standby and four operating high-voltage inverters (VFD1 to VFD4) as an example.

[0048] (b) Faulty inverter, generally refers to an in-service inverter that has a fault during operation. The present invention is described using an in-service inverter (VFD1) as an example.

[0049] (c) Standby inverter, generally refers to a public standby inverter. The standby inverter serves as a public standby during the normal operation of the operating inverter, and also serves as a recovery function in the event of a switchback failure during the switchback phase after it is put into operation.

[0050] (d) Inverter re-switching generally refers to the re-switching of a faulty inverter after repair.

[0051] FIG1 is a schematic diagram of the electrical principle of a multi-operation-one-standby frequency converter according to a specific embodiment of the present invention.

[0052] As shown in Figure 1, taking "four in operation and one standby" as an example, the multi-in operation and one standby inverter switchback control system 100 of this embodiment includes multiple in-operation inverters (VFD1~VFD4) 9~12, a standby inverter (VFD0) 26, main pump motors (M1~M4) 21~24 corresponding to the multiple in-operation inverters 9~12 and the standby inverter 26 respectively, and a power plant control system (PLS).

[0053] Each operating frequency converter 9 to 12 is connected to the corresponding main pump motor 21 to 24 through the corresponding output circuit breaker 32 to 35 to drive the corresponding main pump motor 21 to 24; each operating frequency converter 9 to 12 includes its own corresponding control system; the standby frequency converter 26 includes its own corresponding control system, and the standby frequency converter 26 is used to replace the operation of one of the multiple operating frequency converters 9 to 12 to drive the corresponding main pump motor.

[0054] Between the output circuit breakers 32-35 of the inverters 9-12 and the main pump motors 21-24, inlet circuit breakers for the main pump motors 21-24 are provided. These inlet circuit breakers include first inlet circuit breakers 3-16 and second inlet circuit breakers 7-20, respectively. The main pump motors 21-24 are used to transport coolant to the reactors of nuclear power plants.

[0055] The multi-operating and one-standby inverter switchback control system 100 further includes an interlocking switching device 27. The interlocking switching device 27 includes at least a plurality of output circuit breakers 28-31, which serve as output circuit breakers 28-31 for the standby inverter 26. The standby inverter 26 is connected to the main pump motors 21-24 corresponding to the plurality of operating inverters 9-12 via the plurality of output circuit breakers 28-31 of the interlocking switching device 27.

[0056] The control systems of the operating frequency converters 9 to 12 and the control system of the standby frequency converter 26 are connected via hard-wired lines to transmit the blocking output operation instruction signal; the hard-wired lines include communication lines.

[0057] Taking "four operations and one standby" as an example, the components and modules related to the embodiment of the present invention include: five inverters (including matching import and export circuit breakers) and one power plant control system (PLS). More specifically, it includes the following parts:

[0058] (1) 5 inverters. Specifically including:

[0059] (a) 5 VFDs (including their respective redundant control systems): 4 in-service VFDs (VFD1 to VFD4) and 1 spare VFD (VFD0).

[0060] (b) Import and export circuit breakers for the inverter: import and export circuit breakers for 4 inverters in operation and 1 spare inverter.

[0061] (c) One set of interlocking switching device: “four operations and one standby” interlocking switching device.

[0062] (d) 4 sections of 10.5KV power busbars.

[0063] (e) Supporting load: 4 first main pump inlet circuit breakers and 4 second main pump inlet circuit breakers, 4 main pump motors (M1~M4).

[0064] (2) One power plant control system (PLS). The PLS is responsible for overall monitoring and control of the main pump inverter from the nuclear power plant's main control system. The PLS communicates with the inverter via, for example, the Profibus DP bus or Modbus communication protocol.

[0065] (3) Other equipment or components, including:

[0066] (a) Hard wiring between devices.

[0067] (b) Software modules corresponding to the redundant control system.

[0068] The functions and effects achieved by the inverter switchback of the present invention include:

[0069] (a) Within the time limit required by the process safety of the reactor coolant system of a nuclear power plant, the faulty inverter can be smoothly switched back after repair, and a function of recovering the inverter from failure of switching back is added.

[0070] (b) Establish the master control status of the standby inverter during the switchback process.

[0071] (c) Realize mutual communication between the control systems of different frequency converters and the power plant control system. Assisted by hard wiring between the control systems of different frequency converters, determine the frequency converter control timing in this application solution, thereby improving the control strategy of the main pump frequency converter.

[0072] As shown in Figure 1, reference numerals 9 through 12 represent the active inverters VFD1 through VFD4, respectively. Their electrical structure, input / output characteristics, and control strategies are identical. Reference numerals 1 through 4 represent the four power buses with electrical parameters of 50 Hz and 10.5 kV. Reference numerals 5 through 8 represent the inlet circuit breakers of the active inverters VFD1 through VFD4, respectively. Reference numerals 32 through 35 represent the outlet circuit breakers of the active inverters VFD1 through VFD4, respectively. These circuit breakers correspond one-to-one with the active inverters 9 through 12 (or VFD1 through VFD4) and serve to isolate the inverter's input and output. Reference numeral 26 represents the standby inverter VFD0. Its electrical functions and primary functional parameters are identical to those of the active inverters 9 through 12 (or VFD1 through VFD4), but the manufacturer, structural details, and control system may differ slightly. Reference numeral 25 represents the inlet circuit breaker of the standby inverter VFD0. The outlet circuit breaker of the standby inverter VFD0 is, for example, contained in an interlocking switching device 27. Each operating inverter is connected to the power supply, such as the power bus, through the corresponding imported circuit breaker.

[0073] 21 to 24 represent the four main pump motors M1 to M4 respectively; 13 to 16 represent the first main pump inlet circuit breaker (corresponding to the main pump motors M1 to M4 respectively); 17 to 20 represent the second main pump inlet circuit breaker (corresponding to the main pumps M1 to M4 respectively);

[0074] The "four-in-operation, one-standby" high-voltage inverter interlocking switching device 27 includes at least output circuit breakers 28-31; 28-31 represent the output circuit breakers for each load from the standby inverter to the main pump motors (M1-M4) 21-24. Interlocking switching device 27 is a combined switching / isolating device connecting the standby inverter to the main pump motors (M1-M4) 21-24. Key components of the interlocking switching device are the standby inverter output circuit breakers 28-31, which correspond one-to-one with the output circuit breakers 32-35 of the active inverters VFD1-VFD4, between the active inverters (VFD1-VFD4) 9-12 and the main pump motors (M1-M4) 21-24.

[0075] Regarding the output circuit breakers 28 to 31 in the interlocking switching device 27, in some embodiments, the output circuit breakers 32 and 28 are locked to each other and cannot be opened or closed at the same time. Only after the corresponding redundant inverter host issues an "unlock" command can individual opening and closing operations be performed; the output circuit breakers 33 and 29 are locked to each other and cannot be opened or closed at the same time. Only after the corresponding redundant inverter host issues an "unlock" command can individual opening and closing operations be performed; the output circuit breakers 34 and 30 are locked to each other and cannot be opened or closed at the same time. Only after the corresponding redundant inverter host issues an "unlock" command can individual opening and closing operations be performed; the output circuit breakers 35 and 31 are locked to each other and cannot be opened or closed at the same time. Only after the corresponding redundant inverter host issues an "unlock" command can individual opening and closing operations be performed.

[0076] When the reactor coolant system is operating, if any of the four active VFDs (VFD1-VFD4) 9-12 fails, the standby VFD (VFD0) 26 must successfully switch into operation according to the configured switching logic within the time specified by the process system, and the faulty active VFD will be smoothly deactivated. Under this reactor coolant system operating condition, the three active VFDs and the standby VFD 26 are in operation.

[0077] If the previously faulty, active inverter needs to be restored after repair, it should be switched back on according to the set switchback logic within the time specified by the process system. The standby inverter 26 should be switched out of operation and back on again. Switching back on the standby inverter 26 and the previously faulty, active inverter execute different control logic.

[0078] FIG2 is a schematic diagram showing the connection of a control interface of a standby frequency converter of multiple main pumps in a specific embodiment of the present invention.

[0079] As shown in Figure 2, the redundant host computer 36 of the standby inverter 26 is a key component and control center for the standby inverter 26 (i.e., the standby inverter's own control system). Each of the active inverters (VFD1-VFD4) 9-12 has a corresponding redundant control host computer, which is also a key component and control center for each of the active inverters (VFD1-VFD4) 9-12. The redundant hosts of the active inverters (VFD1-VFD4) 9-12 are connected to the redundant host computer 36 of the standby inverter (VFD0) 26, for example, via a Profibus DP bus 312.

[0080] The operating VFDs 9-12 (VFD1-VFD4) are connected to their respective inlet circuit breakers 5-8 and outlet circuit breakers 32-35 via hard wiring. Hard wiring can also be called hard-connected wires, which include, for example, copper wires and communication wires.

[0081] The redundant host computer 36 of the standby inverter (VFD0) 26 and the redundant hosts of the operating inverters (VFD1-VFD4) 9-12 are connected to the power plant control system (PLS), for example, via a Profibus DP bus. The standby inverter (VFD0) 26 is also connected to the standby inverter inlet circuit breaker 25 and the standby inverter outlet circuit breakers 28-31 in the interlocking switching device 27, for example, via hard wiring.

[0082] FIG3 is a flow chart of a switchback control method for multiple-operation-one-standby inverters according to a specific embodiment of the present invention.

[0083] As shown in FIG3 , steps 101 to 120 represent the control strategy and action logic of any one of the operating inverters ( VFD1 to VFD4 ) 9 to 12 during the switching back process.

[0084] The following describes the switchback process using the operating inverter (VFD1) 9 as an example.

[0085] Steps 201 to 208 (details will be described later) represent the control strategy and action logic of the standby inverter (VFD0) 26 during the switchback process. The control strategy and action logic of the operating inverters (VFD1 to VFD4) 9 to 12 during the switchback process are the same.

[0086] The switchback logic and control strategy shown in the flowchart of FIG3 can be implemented, for example, by cooperating with the hard wiring and Profibus DP bus communication processes in FIG1 and FIG2.

[0087] In one embodiment, one of the four operating inverters is selected, such as the operating inverter (VFD1) 9, and its switching back strategy is:

[0088] (1) Five high-voltage inverters, including four in operation and one spare inverter, as well as hard wiring and communication cables to ensure the smooth implementation of the switching test.

[0089] (2) For example, if the operating inverter 9 fails during operation, the standby inverter 26 is successfully put into operation. After the operating inverter 9 fails and needs to be switched back into operation, the standby inverter 26 will be put into standby state again after the switchback is successful.

[0090] (3) The switchback command comes from, for example, a power plant control system (PLS) outside the inverter group.

[0091] (4) During the switching-back process, signal transmission is carried out by combining communication and hard wiring. The control strategy corresponding to the switching-back control method is implemented through the power plant control system (PLS) control software and the redundant control system software of the operating inverter 9 and the standby inverter 26.

[0092] (5) Hard wiring between redundant control systems of different inverters (eg, hard wiring line 311 indicated in FIG. 2 ).

[0093] (6) The standby inverter 26 takes the master position during the switching back process.

[0094] (7) Based on the reactor coolant system process requirements, the criteria for successful resetting are, for example, "the resetting time meets the limit requirements" + "the output torque of the operating inverter 9 is normal." Otherwise, the process switches to the "resetting failure" control process (resetting failure recovery function), and the standby inverter 26 resumes outputting torque and taking over the load.

[0095] (8) During the switchback control process, the relevant electrical signals are fed back normally.

[0096] The normal startup and operation principle of the frequency converter in operation involved in the present invention is as follows:

[0097] Referring to Figure 1 , the four main pumps share the same power supply method. Specifically, power is supplied from the plant power system via four power buses 1-4, with electrical parameters of, for example, 50 Hz, 10.5 kV. These buses pass through inverter inlet circuit breakers 5-8, in-service inverters 9-12, inverter outlet circuit breakers 32-35, the first main pump inlet circuit breaker (13-16), and the second main pump inlet circuit breaker (17-20), respectively, to the main pump motors 21-24. The rated power supply for each main pump motor is, for example, 60 Hz, 6.9 kV.

[0098] While the active VFDs 9-12 are operating normally, after the inlet circuit breaker 25 of the standby VFD 26 is closed and precharging is complete, the redundant master 36 of the power plant control system (PLS) starts operating. The VFD output is blocked, and the outlet circuit breakers 28-31 of the interlocking switching device 27 are opened, placing the standby VFD 26 in hot standby mode. The four active VFDs 9-12 start the main pump motors 21-24 and operate as a group.

[0099] Under the normal power supply mode of the main pump, the switching mode of the standby inverter 26 is: through the 50Hz, 10.5kV power bus 1 of the factory power system, through the standby inverter inlet circuit breaker 25, the standby inverter 26, the standby inverter interlocking switching device 27 (including the outlet circuit breakers 28~31), through logic control (fault switching), selectively through the single electrical circuit of the first main pump inlet circuit breaker (13~16) and the second main pump inlet circuit breaker (17~20), to supply power to a specific one of the main pump motors 21~24.

[0100] The present invention relates to a certain type of reactor single main pump inverter fault switching mode, the working principle of which is as follows:

[0101] Referring to Figure 2, taking the sudden failure of the operating inverter 9 as an example, the power plant control system (PLS) issues a command, the outlet circuit breaker 32 of the operating inverter 9 is disconnected, the outlet circuit breaker 28 of the driving interlocking switching device 27 is closed, the standby inverter 26 is phase-locked to track the idling main pump motor 21, and takes over the load to supply power to it, completing the fault switching within the specified time. The faulty operating inverter 9 exits operation. If any operating inverter fails, after the standby inverter 26 is successfully switched and put into operation, the faulty operating inverter 9 exits the original grouping, and the standby inverter 26 joins the grouping operation. The operating requirements of the reactor coolant system determine that the fault switching involving the main pump (including the power supply) must be completed within the specified time.

[0102] Taking the operating frequency converter (VFD1) 9 as an example, the operating frequency converter 9 involved in the present invention, which was originally shut down due to a fault, should be restored to operation after repair. It should be restored to operation within the time specified by the process system in accordance with the set switchback logic, and the standby frequency converter 26 should be shut down and restored to standby.

[0103] The preparations and conditions before inverter switching back include:

[0104] (a) The external plant control system (PLS) operates normally.

[0105] (b) The standby inverter (VFD0) 26 and the operating inverters (VFD2-VFD4) 10-12 are operating normally and grouped together. The main pump motors (M1-M4) 21-24 driven by each of them and the corresponding reactor coolant systems are operating normally.

[0106] (c) In-service inverter (VFD1) 9 has been repaired and is in the process of being put back into operation. The auxiliary power supply and cooling system of the inverter are functioning normally, and signal communication between the inverter and other equipment is normal.

[0107] 3 , the present invention provides a method for controlling the switching back of multiple operating and one standby inverters. Taking the switching back of the operating inverter (VFD1) 9 as an example, the power plant control system (PLS) and the standby inverter 26 cooperate in the switching back. The detailed implementation process is as follows:

[0108] Step 100: Reset of the operating inverter (VFD1) 9 begins. Step 101: The fault in the operating inverter (VFD1) 9 has been repaired, and the conditions for resuming operation are met. Preparatory work for the reset is complete, and the prerequisites are met. Step 102: The inlet and outlet circuit breakers of the operating inverter 9 are returned to their operating positions.

[0109] In some embodiments, the control system of each operating inverter is configured to: when the standby inverter replaces the operating inverter, perform the inverter pre-charging operation by instructing the import circuit breaker to close; after the pre-charging operation is completed, send a pre-charging completion signal to the power plant control system (PLS) and receive the switchback preparation instruction issued by the power plant control system.

[0110] Specifically, in step 103, the power plant control system (PLS) sends a "pre-charge" instruction to the operating inverter 9; in step 104, the operating inverter 9 sends an instruction through its own redundant host, and instructs its import circuit breaker 5 to close through hard wiring to supply power to the operating inverter 9; in step 105, the operating inverter 9 executes the "pre-charge" instruction under the control of its own redundant host; in step 106, the redundant host of the operating inverter 9 determines that its internal rectifier output voltage meets the requirements within the specified time, and the inverter "pre-charge" link is completed; then, in step 107, the operating inverter 9 transmits a "pre-charge completion" signal to the power plant control system (PLS), informing the main control system that the inverter is ready for load.

[0111] Next, in step 108, the operating inverter 9 meets the switchback condition and waits for the "switchback" instruction issued by the power plant control system (PLS).

[0112] In some embodiments, the control system of each operating inverter is configured to: release the electrical locking state between the output circuit breaker of the standby inverter and the output circuit breaker of the replaced operating inverter according to the re-switching preparation instruction, so that the output circuit breaker of the standby inverter and the output circuit breaker of the replaced operating inverter can be closed at the same time; control the output circuit breaker of the replaced operating inverter to switch from the open state to the closed state; receive the operating signal of the main pump motor driven by the replaced operating inverter, and control the replaced operating inverter to perform tracking phase-locked operation according to the instruction requirements; after the tracking phase-locked operation is completed, send a re-switching enable ready signal to the power plant control system.

[0113] Specifically, in step 109 , the power plant control system (PLS) sends a “switching back preparation” instruction to the redundant host of the operating frequency converter 9 .

[0114] In step 110, after the redundant host of the operating inverter 9 receives the "reverse switching preparation" instruction sent down by the power plant control system (PLS), the electrical interlock between the output circuit breaker 32 of the operating inverter 9 and the output circuit breaker 28 of the standby inverter 26 (VFD0) is released (this interlock restricts the two circuit breakers from being closed at the same time).

[0115] In step 111, after the operating inverter 9 releases the electrical interlock between its outlet circuit breaker 32 and the outlet circuit breaker 28 of the backup circuit breaker 26 (VFD0), its redundant host (the redundant host is one of the specific implementation methods of the aforementioned redundant control system) instructs the outlet circuit breaker 32 to close.

[0116] Step 112: When the inverter 9 receives the operation signal of the main pump motor 21, which includes signals such as speed, torque, drive voltage, drive current and its phase, the inverter tracking phase lock function is started.

[0117] In step 113, the operating frequency converter 9 successfully tracks and phase-locks the main pump motor 21 (ie, the tracking and phase-locking operation is completed).

[0118] In step 114, the operating frequency converter 9 transmits a "reverse switching enable ready" signal to the power plant control system (PLS), which means that the frequency converter can perform the frequency conversion output function.

[0119] At this time, once the operating inverter 9 receives and determines the "standby inverter 26 blocks output" signal through the hard wiring between it and the standby inverter 26, the operating inverter 9 starts to execute the step of "outputting torque" to the main pump motor 21.

[0120] In some embodiments, the power plant control system is configured to: issue a switchback instruction to the control system of the standby inverter based on the switchback enable ready signal.

[0121] The control system of the standby inverter is configured to: issue a blocking output instruction based on the switchback instruction, so that the standby inverter no longer outputs torque to stop driving the main pump motor connected to the standby inverter; and issue a blocking output operation indication signal to the control system of the operating inverter that is replaced by the standby inverter.

[0122] Specifically, concurrently with steps 101-113, the following steps are performed: Step 201: Standby inverter 26 executes group operation. Step 202: The power plant control system (PLS) issues a "switchback" command to the redundant master 36 of standby inverter 26. Step 203: Upon receiving the "switchback" command from the PLS, the redundant master 36 of standby inverter 26 executes the "output blocking" step, and standby inverter 26 ceases to output torque. The "standby inverter 26 output blocking" signal is transmitted to the active inverter 9 via the hard wiring between the active inverter 9 and the standby inverter 26.

[0123] In some embodiments, the control system of the standby inverter 26 is further configured to maintain a tracking phase-locked state of the main pump motor previously driven by the standby inverter 26 after issuing a blocking output instruction and a blocking output operation indication signal.

[0124] Specifically, in step 204, the standby frequency converter 26 continues to track and phase-lock the main pump motor 21 (maintaining hot standby so as to output torque in time and resume taking over the main pump motor 21 when the operating frequency converter 9 fails to switch back).

[0125] In some embodiments, the control system of the operating inverter replaced by the standby inverter 26 is further configured to: after receiving the blocking output operation indication signal, start outputting torque according to the result of tracking the phase-locked operation to drive the corresponding main pump motor.

[0126] Specifically, in step 115, after receiving the "standby inverter 26 output blocked" signal, the active inverter 9 begins formally switching back and begins the first switching back timing point (e.g., T1, marking the start of the switching back timing). After a delay of X1 milliseconds (X1 is, for example, 5 to 50), the active inverter 9 begins "outputting torque" to the main pump motor 21. In step 116, the active inverter 9 outputs torque to the main pump motor 21.

[0127] In some embodiments, the control system of the operating inverter that is replaced by the standby inverter is also configured to: after starting to output torque to drive the corresponding main pump motor, delay for a first time interval to determine whether the driving signal currently output by the operating inverter meets the preset driving conditions; if it meets the preset driving conditions, send a switchback success signal to the power plant control system (PLS).

[0128] Specifically, in step 117, the logic judgment link is entered, and based on the preset driving conditions, it is judged whether the operating frequency converter 9 "outputs normally". If the output signal of the operating frequency converter 9 (for example, including speed, torque, voltage, current and its phase signal) is normal, it means that the operating frequency converter 9 has officially taken over the driving of the main pump motor 21, then step 118 is executed, and the second re-switching timing point is started (for example, recorded as T2, indicating the end of the re-switching timing). The time difference between the two timing points is the re-switching completion time T (T=T2-T1); if the output of the operating frequency converter 9 is abnormal, it means that the operating frequency converter 9 "failed to re-switched", and steps 122, step 123, step 124 (the specific content is described later) and subsequent links are executed. The re-switching completion time T is also the first time interval.

[0129] In some embodiments, the control system of the standby inverter is further configured to: issue a disconnect instruction for the output circuit breaker of the standby inverter based on the received successful re-switching instruction; the control system of the operating inverter replaced by the standby inverter is further configured to: restore the electrical locking state between the output circuit breaker of the standby inverter and the output circuit breaker of the replaced operating inverter, so that the output circuit breaker of the standby inverter and the output circuit breaker of the replaced operating inverter cannot be closed at the same time.

[0130] Specifically, in step 118, if the result of step 117 is "Y (yes)", a delay of X2 seconds is performed, where X2 is, for example, a value between 60 and 120 seconds. This delay of X2 seconds is also referred to as the second delay time interval. This second delay time interval is primarily intended to ensure stable operation of the inverter after switching. This second delay time interval is optional if the switchback is successful.

[0131] In step 119, the outlet circuit breaker 28 of the standby inverter 26 is opened (based on the disconnection instruction of the outlet circuit breaker 28 issued by the control system 36 of the standby inverter 26), and the redundant host instruction of the operating inverter 9 restores the electrical interlock between its outlet circuit breaker 32 and the outlet circuit breaker 28 of the standby inverter 26.

[0132] As mentioned above, in some embodiments, the control system of the operating inverter replaced by the standby inverter is further configured to send a switchback success signal to the power plant control system if the preset driving conditions are met.

[0133] Specifically, in step 120, the operating inverter 9 is successfully switched back and resumed operation. The main pump inverter is regrouped.

[0134] Step 121: The operating inverter 9 transmits a "successful switching back, VFD1 is running" signal (i.e., a successful switching back signal) to the PLS, and informs the power plant control system of the switching back execution result.

[0135] At step 300 , the switchback control process ends.

[0136] In summary, during the switchback process, the PLS issues a "switchback" command to the redundant master of standby inverter 26 at step 202. The subsequent switchback of active inverter 9 occurs at step 203. Through the hard wiring between standby inverter 26 and active inverter 9, redundant master 36 of standby inverter 26 transmits its "standby inverter 26 output blocked" signal to active inverter 9. This signal triggers the switchback of active inverter 9, which has successfully tracked and phase-locked the inverter.

[0137] The time difference between the two timing points is the switchback completion time T. According to the safety requirements of the reactor coolant system of the nuclear power plant, this time is set between 0.5 and 1.5 seconds, for example.

[0138] In step 204 , the standby frequency converter 26 hands over the driving right of the main pump motor 21 , maintains tracking phase lock, and is ready to output torque and drive the main pump motor 21 again at any time.

[0139] In some embodiments, the control system of the in-service inverter replaced by the standby inverter is further configured to: if it is determined that the drive signal currently output by the in-service inverter does not meet the preset drive conditions, instruct the in-service inverter to disconnect the output circuit breaker; send a retry failure signal to the control system of the standby inverter; and restore the electrical lock state of the output circuit breaker of the standby inverter and the output circuit breaker of the replaced in-service inverter, so that the output circuit breaker of the standby inverter and the output circuit breaker of the replaced in-service inverter cannot be closed at the same time. The control system of the standby inverter is further configured to: based on the retry failure signal, send a cancel block output operation instruction to cause the standby inverter to resume outputting torque to continue driving the main pump motor connected to the standby inverter.

[0140] Specifically, if the judgment result of step 117 is “N (No)”, that is, the operating inverter 9 fails to output the driving signal normally, the following steps 122 , 123 , and 124 are executed synchronously.

[0141] Specifically, in step 122, since it is determined based on step 117 that the switching back of the operating inverter 9 is unsuccessful, the operating inverter 9 instructs its inlet circuit breaker to open.

[0142] Step 123 , the operating inverter 9 transmits a “failed switching back, host failure” signal to the PLS, informing the main control system of the switching back result of the operating inverter 9 .

[0143] In step 124 , the operating inverter 9 transmits a signal to the standby inverter 26 through the hard wiring between the standby inverter 26 and the operating inverter 9 , instructing the operating inverter 9 to switch the execution of driving the main pump motor 21 back to the standby inverter 26 .

[0144] In step 125, the output circuit breaker 32 of the active inverter 9 is opened, and the control system of the active inverter 9 restores the electrical interlock between its output circuit breaker 32 and the output circuit breaker 28 of the standby inverter 26. If the switchback is unsuccessful, the standby inverter 26 is driving the main pump motor 21. In this case, the corresponding two circuit breakers need to be locked to prevent them from being closed simultaneously.

[0145] At this point, the operation of the operating inverter 9 in the "return switch" link is completed.

[0146] The following steps are subsequent actions of the standby inverter 26 after the operating inverter 9 fails to switch back.

[0147] In some embodiments, the control system of the standby inverter is further configured to maintain a tracking phase-locked state of the main pump motor previously driven by the standby inverter after issuing a blocking output instruction and a blocking output operation indication signal.

[0148] Specifically, in step 204, the standby inverter 26 continues to track and phase-lock the main pump motor 21. In other words, the standby inverter 26 remains in hot standby mode so that it can output torque in time and resume taking over the main pump motor 21 when the operating inverter 9 fails to switch back.

[0149] As mentioned above, in some embodiments, the control system of the standby inverter is further configured to: based on the re-switching failure signal received by the standby inverter, issue a cancel block output operation instruction to enable the standby inverter to output torque again to continue driving the main pump motor connected to the standby inverter.

[0150] Specifically, in step 205, based on the restoration of step 125, the electrical interlock between the outlet circuit breaker 32 of the operating inverter 9 and the outlet circuit breaker 28 of the standby inverter 26, and the transmission of the auxiliary contact interlocking signal of the outlet circuit breaker 32 of the operating inverter 9 (the signal is transmitted, for example, through hard wiring), the standby inverter 26 outputs torque and re-drives the main pump motor 21. This action can also be referred to as the standby inverter 26 resuming to take over the main pump motor 21.

[0151] In some embodiments, the control system of the standby inverter is further configured to: instruct the standby inverter to re-output torque to continue driving the main pump motor connected to the standby inverter, and then enter the link of determining whether the drive signal currently output by the standby inverter meets the preset drive conditions; if it meets the preset drive conditions, a corresponding indication signal is sent to the power plant control system indicating a switchback failure and the standby inverter continues to operate.

[0152] Specifically, in step 206, the logic judgment link is entered to determine whether the "output of the standby inverter 26 is normal" based on the preset driving conditions. If the output of the standby inverter 26 is abnormal, it means that the standby inverter 26 has failed to take over the driving of the main pump motor again after the "failed to switch back", and step 207 is executed. If the output (speed, torque, voltage, current and its phase) of the standby inverter 26 is normal, it means that the standby inverter 26 has officially taken over the driving of the main pump motor 21, and step 208 is executed. In step 208, if the result of step 206 is "Y (Yes)", the redundant host 36 of the standby inverter 26 transmits a "failed to switch back, VFD0 is running" signal to the PLS.

[0153] In some embodiments, the control system of the standby inverter is further configured to send a switchback failure and an indication signal corresponding to a system failure to the power plant control system if it is determined that the drive signal currently output by the standby inverter does not meet the preset drive conditions.

[0154] Specifically, in step 207, if the result of step 206 is "N (No)", the redundant host 36 of the backup inverter 26 transmits a "comprehensive fault" signal to the PLS. This indicates that after the active inverter 9 failed to switch back, the backup inverter 26 failed to take over the driving of the main pump motor 21. This fault information is transmitted to the main control system where the PLS is located.

[0155] Step 300, the switchback is completed. This means that after the operating inverter 9 fails to switch back, the standby inverter 26 takes over the action of driving the main pump motor 21 again successfully, and this status information is transmitted to the main control system where the PLS is located.

[0156] At this point, the cooperation action of the standby inverter 26 in the "switching back" link of the operating inverter 9 is completed.

[0157] In summary, steps 123 to 125 and steps 204 to 208 are rescue operations for the operating inverter 9 after the switching back fails.

[0158] Among them, steps 124 to 125 are for notifying the standby inverter 26 to take rescue operations after the operating inverter 9 fails to switch back.

[0159] In steps 204-208, the standby inverter 26 temporarily relinquishes control of the main pump motor 21, maintaining tracking and phase lock, ready to resume outputting torque and driving the main pump motor 21. If the active inverter 9 successfully switches back, the standby inverter 26 enters standby mode. If the active inverter 9 fails to switch back, the standby inverter 26 resumes outputting torque and driving the main pump motor 21. The success or failure of the standby inverter 26's re-output operation transmits a corresponding fault signal to the PLS.

[0160] The multi-operation and one-standby inverter switchback control system and method of the present invention has the following advantages:

[0161] (1) A multi-operation and one-standby high-voltage inverter switchback control technology is proposed

[0162] Specifically, the present invention proposes a logic control and strategy for inverter switching back;

[0163] Formulated the switchback logic flow and control sequence after the failure of multiple-operation-one-standby high-voltage inverters is repaired;

[0164] This improves the control strategy of the frequency converter and main pump redundant control system.

[0165] (2) By establishing the transmission path of the inverter switchback command, communication and signal transmission between different control systems can be realized

[0166] (a) For communication between different control systems, such as power plant control systems and redundant inverter control systems from different manufacturers, signal transmission is achieved through a combination of communication and hardwiring. Specifically, PROFIBUS and DP buses are used to connect the control systems, enabling communication between inverter control systems and between the inverter control system and the power plant control system. Hardwiring is used to connect the inlet and outlet circuit breakers associated with the inverters, enabling communication between redundant inverter control systems and power plant control systems.

[0167] (b) The inverter switchback command comes from, for example, the upstream power plant control system (PLS).

[0168] (c) During the switchback process, relevant command signals and action result signals can be fed back to the inverter redundant control system and the power plant control system (PLS) in a timely manner.

[0169] (3) In this solution, the standby inverter is in the master position during the switching back process

[0170] In the present application scheme, the standby inverter is in the master control position during the switching back process. After the power plant control system (PLS) sends a "switching back" instruction to the operating inverter 9 and the standby inverter 21, the subsequent switching back process control and switching back failure recovery control are all controlled by the standby inverter 21.

[0171] (4) This solution provides the criteria for determining whether a switchback is successful or unsuccessful.

[0172] Specifically, the criteria for successful resetting can be summarized as: "the inverter output is normal" + "the resetting time meets the time limit requirement".

[0173] Normal inverter output means that the speed, torque, voltage, current and phase of the inverter output are normal.

[0174] Regarding the time limit requirement for the switch-back time, according to the process requirements of the reactor coolant system, if the switch-back time meets the time limit requirement, for example, it is set between 0.5 seconds and 1.5 seconds.

[0175] (5) This solution describes the strategy for recovering from a failed switchback.

[0176] In the multi-operation and one-standby high-voltage inverter switchback process, a "switchback failure" recovery control strategy was formulated.

[0177] In Figure 3 , according to the switchback control flow, the standby inverter 26 temporarily relinquishes control of the main pump motor 21 while maintaining tracking and phase lock, ready to resume outputting torque and driving the main pump motor 21. If the active inverter 9 successfully switches back, the standby inverter 26 enters a standby state. If the active inverter 9 fails to switch back, the standby inverter 26 resumes outputting torque and driving the main pump motor 21.

[0178] The application solution can achieve smooth switching back of the faulty inverter after repair within the time limit required by the process of the reactor coolant system of the nuclear power plant, and adds a function of recovering the inverter from failed switching back.

[0179] This application fully describes the inventor's proposed "Multi-operation, One-standby Inverter Switchback Control System and Method." For ease of explanation, the inventors specifically illustrate the inverter switchback process using a four-operation, one-standby inverter. In practice, this solution also includes the following variations:

[0180] (1) The scope of “multiple transport and one reserve” can be varied

[0181] In the field of industrial production, multiple inverters often run in parallel, such as multiple drives to one (multiple inverters drive one motor load), one drive to multiple (one inverter drives multiple motor loads), mutual backup (multiple inverters are in operation at the same time, multiple inverters are in standby state, and they are backup for each other), multiple backup to one (multiple inverters are in operation at the same time, and one inverter is in standby state), etc., all of which can be switched back based on the "multiple-operation-one-standby inverter switchback control system and method" of this application.

[0182] Therefore, for the "many-to-one backup" inverter switchback technology, the "many" here can be 1, 2, 3, 4, 5, 6, 7, or more. It is also applicable to inverter configurations such as multiple-to-one, one-to-many, and mutual backup.

[0183] (2) The signal type, source, communication method and logical relationship of the switching device can be changed

[0184] The inventor proposed "a multi-operating and one-standby inverter switchback control system and method". The embodiments described earlier in this article mainly describe the logical relationship and control strategy between the operating inverter, the standby inverter, and the upstream power plant control system.

[0185] In this invention, the inventors propose data exchange between three different control systems: an in-service inverter, a standby inverter, and an upstream power plant control system. The power plant control system is the upstream system, while the control systems for the in-service inverter and the standby inverter are downstream, parallel control systems. In actual production systems, these control systems can be in a parallel relationship, and the in-service inverter and the standby inverter can also be upstream and downstream control systems. Additional upstream, parallel, and downstream control systems can also be added between these three, and there can be multiple, i.e., more than one, control system.

[0186] In the present invention, the inventor proposes to realize mutual communication among the three through a bus, such as Profibus DP bus. In actual design, other communication protocols such as Modbus can also be used for realization.

[0187] During the specific equipment failback process, the types and number of signal interactions between the operating VFD, standby VFD, and power plant control system can be expanded, the scope of hard wiring can be expanded, and the mutual feedback of process control signals and instructions can be further enhanced. For example, process signals can be added to participate in logic control, parameter monitoring, and smooth adjustment during the failback process.

[0188] The inventors have provided a criterion for determining whether the re-switching of a multi-operation and one-standby high-voltage inverter is successful or not. The conditions of this criterion are variable and can be simply added or logically added according to the needs of the process and control logic, such as adding a certain process signal, such as adding a status signal of a certain circuit breaker to participate in the logical judgment, etc.

[0189] Furthermore, to ensure the safety of process equipment, the switchback control logic can be enriched and adaptively modified and improved according to different process requirements. Furthermore, auxiliary monitoring functions such as audible and visual alarms / indicators can be considered during the switchback process.

[0190] (3) The equipment to be switched back has a wide range of applications

[0191] The inventor proposed a "multi-operation and one-standby high-voltage inverter switchback control system and method", which uses communication technology and hard wiring, matching control timing and newly set control logic to realize mutual communication between high-voltage inverters of the same type but different control systems and power plant control systems, so as to achieve the purpose of mutual switching of equipment.

[0192] The aforementioned embodiments of this article can be applied to high-voltage inverters. In the actual industrial field, the objects of re-switching can also be low-voltage inverters, special drive devices and other electrical equipment. When these electrical equipment participate in multi-branch process flows, they can use the technology involved in the present invention to cut in or re-switch the equipment.

[0193] 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 multi-operation and one-standby inverter switchback control system, comprising: There are multiple frequency converters in operation, and each frequency converter is connected to the corresponding main pump motor through the corresponding outlet circuit breaker to drive the corresponding main pump motor; Each inverter in operation includes its own corresponding control system; A standby frequency converter, including its own corresponding control system, wherein the standby frequency converter is used to replace the operation of one of the multiple operating frequency converters to drive the main pump motor corresponding to the replaced operating frequency converter; Power plant control systems; The control system of each inverter in operation is configured as follows: receiving a switchback preparation instruction from a power plant control system when the standby frequency converter replaces one of the multiple operating frequency converters; releasing the electrical locking state between the outlet circuit breaker of the standby inverter and the outlet circuit breaker of the replaced inverter according to the switchback preparation instruction, so that the outlet circuit breaker of the standby inverter and the outlet circuit breaker of the replaced inverter can be closed at the same time; Controlling the outlet circuit breaker of the replaced frequency converter to switch from an open state to a closed state; receiving an operating signal of a main pump motor driven by the replaced frequency converter, and controlling the replaced frequency converter to perform a tracking phase-locked operation according to an instruction; After the tracking and phase-locking operation is completed, a switchback enable ready signal is sent to the power plant control system.

2. The multi-operation-one-standby inverter switchback control system according to claim 1, characterized in that: The power plant control system is configured to: Based on the switchback enable ready signal, a switchback instruction is issued to the control system of the standby inverter.

3. The multi-operation-one-standby inverter switchback control system according to claim 2, characterized in that: The control system of the standby inverter is configured as follows: Based on the switchback instruction, issuing a blocking output instruction so that the standby frequency converter no longer outputs torque, thereby stopping driving the main pump motor connected to the standby frequency converter; Sending a blocking output operation instruction signal to the control system of the replaced frequency converter; The control system of the replaced frequency converter is further configured as follows: After receiving the blocking output operation instruction signal, the output torque is started according to the result of the tracking phase-locked operation to drive the corresponding main pump motor.

4. The multi-operation-one-standby inverter switchback control system according to claim 1, characterized in that: It also includes an interlocking switching device; the interlocking switching device includes at least a plurality of outlet circuit breakers, which serve as outlet circuit breakers of the backup inverter; The standby frequency converter is connected to the main pump motors corresponding to the multiple frequency converters in operation through multiple output circuit breakers of the interlocking switching device.

5. The multi-operation-one-standby inverter switchback control system according to claim 3, characterized in that: The control system of the operating frequency converter and the control system of the standby frequency converter are connected via a hard-wired line to transmit the output blocking operation instruction signal; the hard-wired line includes a communication line.

6. The multi-operation-one-standby inverter switchback control system according to claim 1, characterized in that: The operating signals of the main pump motor include speed, torque, drive voltage, drive current and phase signal.

7. The multi-operation-one-standby inverter switchback control system according to claim 3, characterized in that: The control system of the standby frequency converter is further configured as follows: After issuing the blocking output instruction and the blocking output operation indication signal, the tracking phase-locked state of the main pump motor previously driven by the standby inverter is maintained; The control system of the replaced frequency converter is further configured as follows: After starting to output torque to drive the corresponding main pump motor, delaying for a first time interval to determine whether the drive signal currently output by the operating frequency converter meets the preset drive conditions; If the preset driving conditions are met, a switchback success signal is sent to the power plant control system.

8. The multi-operation-one-standby inverter switchback control system according to claim 7, characterized in that: The control system of the standby frequency converter is further configured as follows: Based on the received switchback success signal, issuing a disconnect instruction for the output circuit breaker of the standby inverter; The control system of the replaced frequency converter is further configured as follows: The electrical locking state between the outlet circuit breaker of the standby frequency converter and the outlet circuit breaker of the replaced frequency converter is restored so that the outlet circuit breaker of the standby frequency converter and the outlet circuit breaker of the replaced frequency converter cannot be closed at the same time.

9. The multi-operation-one-standby inverter switchback control system according to claim 7, characterized in that: The control system of the replaced frequency converter is further configured as follows: If it is determined that the driving signal currently output by the operating inverter does not meet the preset driving conditions, the output circuit breaker of the operating inverter is instructed to be disconnected; Sending a switchback failure signal to the control system of the standby inverter; Restoring the electrical interlocking state between the outlet circuit breaker of the standby frequency converter and the outlet circuit breaker of the replaced frequency converter, so that the outlet circuit breaker of the standby frequency converter and the outlet circuit breaker of the replaced frequency converter cannot be closed at the same time; The control system of the standby frequency converter is further configured as follows: Based on the switchback failure signal, a command to cancel the blocking output operation is issued to enable the standby inverter to output torque again to continue driving the main pump motor connected to the standby inverter.

10. The multi-operation-one-standby inverter switchback control system according to claim 9, characterized in that: The control system of the standby frequency converter is further configured as follows: Instructing the standby inverter to re-output torque to continue driving the main pump motor connected to the standby inverter, and then entering the link of determining whether the drive signal currently output by the standby inverter meets the preset drive conditions; If the preset driving conditions are met, an indication signal corresponding to the switchback failure and the continued operation of the standby frequency converter is sent to the power plant control system.

11. The multi-operation-one-standby inverter switchback control system according to claim 10, characterized in that: The control system of the standby frequency converter is further configured as follows: If it is determined that the driving signal currently output by the standby inverter does not meet the preset driving condition, an indication signal corresponding to a switchback failure and a system fault is sent to the power plant control system.

12. The multi-operation-one-standby inverter switchback control system according to claim 1, characterized in that: Each operating inverter is connected to the power supply through the corresponding imported circuit breaker. The control system of each operating inverter is also configured as follows: When the standby frequency converter replaces one of the multiple frequency converters in operation, and before receiving a switchback preparation instruction from the power plant control system, the frequency converter pre-charge operation is performed by instructing the inlet circuit breaker to close; After the pre-charging operation is completed, a pre-charging completion signal is sent to the power plant control system.

13. The multi-operation-one-standby inverter switchback control system according to claim 1, characterized in that: The main pump motor is used for transporting coolant in reactors of nuclear power plants.

14. The multi-operation-one-standby inverter switchback control system according to claim 1, characterized in that: An inlet circuit breaker of the main pump motor is also provided between the outlet circuit breaker of the operating frequency converter and the main pump motor.

15. A method for controlling a switchback of multiple frequency converters in operation and one standby frequency converter, wherein the multiple frequency converters in operation and one standby frequency converter comprise multiple frequency converters in operation and one standby frequency converter; the method comprising: Each operating frequency converter receives a switchback preparation instruction from the power plant control system when the standby frequency converter replaces the operating frequency converter; releasing the electrical locking state between the outlet circuit breaker of the standby inverter and the outlet circuit breaker of the replaced inverter according to the switchback preparation instruction, so that the outlet circuit breaker of the standby inverter and the outlet circuit breaker of the replaced inverter can be closed at the same time; Controlling the outlet circuit breaker of the replaced frequency converter to switch from an open state to a closed state; receiving an operating signal of a main pump motor driven by the replaced frequency converter, and controlling the replaced frequency converter to perform a tracking phase-locked operation according to an instruction; After the tracking phase-locked operation is completed, the operating frequency converter to be replaced sends a switchback enable ready instruction to the power plant control system.

Images