Direct-current power transmission valve control system and communication redundancy control method

Abstract

The invention belongs to the field of direct-current power transmission valve control, and particularly relates to a direct-current power transmission valve control system and a communication redundancy control method. The system comprises an interface board, at least two control units and at least two communication summarizing boards, wherein the interface board is used for being connected to a corresponding converter valve sub-module control end; the interface board comprises processing modules which are in one-to-one correspondence with the communication summarization boards and are used for communicating with the corresponding communication summarization boards; at most one control unit is in an on-duty state; the communication summary board is used for sending the communication state between the communication summary board and the corresponding processing module and the communication state between the corresponding processing module and the converter valve sub-module to the on-duty control unit; the control unit is also used for judging whether a communication loop of each communication gathering board communicating with the converter valve sub-module through the corresponding processing module is normal or not according to the communication state in the on-duty state, and setting the processing module corresponding to one normal communication loop in each interface board to be in the on-duty state; and forwarding the instruction to the sub-module control end through the processing module.

Description

Technical Field

[0001] The present invention belongs to the field of direct current transmission valve control, and in particular relates to a direct current transmission valve control system and a communication redundancy control method. Background Art

[0002] During flexible DC transmission, the valve control system can accurately control the on / off state of the converter valve switch according to the superior control instructions, thereby achieving precise regulation of DC current and voltage. This precise control is the basis for ensuring the stable operation of the flexible DC transmission system. The valve control system plays an important role in the field of flexible DC transmission. It can reduce energy loss and improve transmission efficiency by accurately controlling the on / off state of the converter valve. It can also quickly respond to grid fluctuations and faults, effectively isolate the fault area, prevent the fault from expanding, and enhance the stability of the transmission system.

[0003] With the continuous development of flexible DC transmission technology, there is an urgent need for the communication reliability of the valve control system. In the traditional DC transmission valve control communication architecture, the valve control system usually includes two control units, the main control unit and the backup control unit; the control unit and the interface unit of the valve control system are directly connected, that is, a single communication loop is formed by directly connecting the main control unit or the backup control unit with the interface unit for communication transmission. This method of using a single communication loop for communication transmission will directly cause the valve control system to switch between the main control unit and the backup control unit when the single communication loop fails. In this case, if there is a difference in the control signals of the main control unit and the backup control unit, it will cause confusion in the control signals received by the control end of the converter valve submodule. After the control system is switched, it will cause disturbances to the entire power grid, and even cause serious consequences such as DC blocking. Summary of the invention

[0004] The purpose of the present invention is to provide a direct current transmission valve control system and a communication redundancy control method, which are used to solve the problem in the prior art that when a single communication circuit fails, the valve control system performs a master-slave switching of the control unit, which easily leads to control signal confusion of the converter valve submodule and causes disturbance to the entire power grid.

[0005] In order to achieve the above-mentioned object, the present invention provides a direct current transmission valve control system, which includes an interface unit and at least two control units, wherein the interface unit includes an interface board for accessing a corresponding converter valve submodule control end and at least two communication aggregation boards; the interface board includes processing modules that communicate with each communication aggregation board in a one-to-one correspondence; at most one of each control unit is in a duty state; the communication aggregation board is used to send the communication state between itself and the corresponding processing module and the communication state between the corresponding processing module and the converter valve submodule to the control unit in the duty state; The control unit is used to determine whether the communication loop through which each communication aggregation board communicates with the converter valve sub-module through the corresponding processing module is normal according to the communication status in the duty state, and set a processing module corresponding to a normal communication loop in each interface board to the duty state, so as to forward the instructions of the control unit to the control end of the converter valve sub-module through the processing module in the duty state.

[0006] Beneficial effects: The present invention provides a new direct current transmission valve control system, which uses a control unit to determine whether the communication loop of each communication summary board communicating with the converter valve submodule through the corresponding processing module is normal according to the communication status in the duty state, and uses the control unit to set the processing module corresponding to a normal communication loop in each interface board to the duty state, so as to use the processing module in the duty state to forward the instructions of the control unit to the converter valve submodule control end. The system can realize at least two redundant communication loops that communicate with the converter valve submodule and are independent of each other based on the interface unit, thereby effectively improving the availability of the interface unit, so as to effectively avoid the valve control system performing the master-slave switching of the control unit once a single communication loop of the interface unit fails, resulting in the control signal received by the converter valve submodule control end being easily confused, which will cause disturbance to the entire power grid after the control system is switched.

[0007] Further, the method of setting a processing module corresponding to a normal communication loop in each interface board to a duty state includes: if the communication state of each communication loop is normal, setting any one processing module in each interface board to a duty state; If the communication status of some of the communication loops is abnormal, a processing module corresponding to the communication loop with normal communication status is set in each interface board as on-duty status; If the communication status of each communication loop is abnormal, then apply to switch another control unit to the duty state, so that the new control unit in the duty state can judge whether the communication loop through which each communication summary board communicates with the converter valve submodule through the corresponding processing module is normal according to the communication status, and set a processing module corresponding to the communication loop with normal communication status to the duty state in each interface board. The present invention also provides a new communication redundancy control method for DC transmission valve control, which judges whether the communication loop through which each communication summary board communicates with the converter valve submodule through the corresponding processing module is normal according to the communication status in the duty state through the control unit of the DC transmission valve control system, and sets a processing module corresponding to a normal communication loop to the duty state in each interface board, so as to forward the instructions of the control unit to the control end of the converter valve submodule through the processing module in the duty state; The valve control system includes an interface unit and at least two control units, the interface unit includes an interface board for accessing the corresponding control end of the converter valve submodule and at least two communication summary boards; the interface board includes processing modules that communicate with each communication summary board one-to-one; at most one of the control units is in a duty state; the communication summary board is used to send the communication state between itself and the corresponding processing module and the communication state between the corresponding processing module and the converter valve submodule to the control unit in the duty state.

[0008] Further, the method of setting a processing module corresponding to a normal communication loop in each interface board to a duty state includes: if the communication state of each communication loop is normal, setting any one processing module in each interface board to a duty state; If the communication status of some of the communication loops is abnormal, a processing module corresponding to the communication loop with normal communication status is set in each interface board as on-duty status; If the communication status of each communication loop is abnormal, an application is made to switch another control unit to the duty state, so that the new control unit in the duty state can judge whether the communication loop of each communication summary board communicating with the converter valve submodule through the corresponding processing module is normal according to the communication status, and set a processing module corresponding to the communication loop with normal communication status in each interface board to the duty state. The communication redundancy control method of DC transmission valve control can achieve the same beneficial effects as the above-mentioned DC transmission valve control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the principle of the DC transmission valve control system in the DC transmission valve control system embodiment; Figure 2 The present invention is a flow chart of setting a processing module corresponding to a normal communication loop in each interface board to a duty state in an embodiment of a direct current transmission valve control system. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0011] DC transmission valve control system implementation example This embodiment provides a direct current transmission valve control system, which includes an interface unit and at least two control units, wherein the interface unit includes an interface board for accessing a corresponding converter valve submodule control terminal and at least two communication aggregation boards; the interface board includes processing modules that communicate with each communication aggregation board in a one-to-one correspondence; at most one of each control unit is in a duty state; the communication aggregation board is used to send the communication state between itself and the corresponding processing module and the communication state between the corresponding processing module and the converter valve submodule to the control unit in the duty state; The control unit is used to determine whether the communication loop through which each communication aggregation board communicates with the converter valve sub-module through the corresponding processing module is normal according to the communication status in the duty state, and set the processing module corresponding to a normal communication loop in each interface board to the duty state, so as to forward the instructions of the control unit to the control end of the converter valve sub-module through the processing module in the duty state.

[0012] Specifically, Figure 1 As shown, in the above-mentioned DC transmission valve control system, the control units are the A system control unit and the B system control unit (the two sets of control units are independent control units); in other embodiments, the number of control units can also be set to more than two. At most one of the control units (i.e., the A system control unit and the B system control unit) is on duty. For example, if the A system control unit is on duty, the B system control unit must not be on duty. The control end of the converter valve submodule is the submodule central control board. In this embodiment, the interface board and the submodule central control board are in a one-to-one correspondence. In other embodiments, multiple submodule central control boards can also be connected to the same interface board to achieve synchronous control.

[0013] The interface unit is configured with two independent communication summary boards and N interface boards (i.e., interface board 1-interface board N), and each interface board is connected to a one-to-one corresponding sub-module central control board; in other embodiments, the number of communication summary boards can also be set to more than two, as long as the number of communication summary boards is consistent with the number of processors configured on each interface board.

[0014] In this embodiment, each interface board is configured with two processors: processor A and processor B (i.e., each processing module that communicates with the corresponding communication summary board). Communication summary board 1 of the interface unit communicates with processor A of all interface boards; communication summary board 2 of the interface unit communicates with processor B of all interface boards. In other embodiments, the number of processors configured for each interface board may also be set to more than two, consistent with the number of communication summary boards, and each communication summary board communicates with the processor corresponding to the communication summary board in the interface board.

[0015] The communication summary board 1 of the interface unit summarizes the communication status between itself and all interface board processors A, as well as the communication status between each interface board processor A and the submodule central control board, and sends it to the control unit; the communication summary board 2 of the interface unit summarizes the communication status between itself and all interface board processors B, as well as the communication status between each interface board processor B and the submodule central control board, and sends it to the control unit. The control unit and the interface unit use a cross-redundant communication method, that is, each communication summary board of the interface unit can communicate with each control unit (such as Figure 1 In the embodiment shown, each communication aggregation board of the interface unit communicates with the A and B system control units).

[0016] For each submodule central control board (i.e., the control end of the converter valve submodule), it can be controlled through two communication loops, "control unit (on-duty state)-communication summary board 1-interface board processor A" and "control unit (on-duty state)-communication summary board 2-interface board processor B". The control unit in the on-duty state determines whether the communication status of the two communication loops is normal based on the information uploaded by the communication summary board and the communication status of the communication summary board received by itself, selects a normal communication loop based on the judgment result, and sets the processor (i.e., processing module) corresponding to the normal communication loop to the on-duty state. In other embodiments, if there are M communication summary boards in the interface unit (M>2), then M interface boards are set in each interface unit. Accordingly, each submodule central control board can be controlled through M communication loops respectively constituted by the control unit in the on-duty state, M communication summary boards, and M interface boards; wherein the control unit in the on-duty state determines whether the communication status of the M communication loops is normal based on the information uploaded by the communication summary board and the communication status of the communication summary board received by itself, selects a normal communication loop based on the judgment result, and sets the processor corresponding to the normal communication loop to the on-duty state. In summary, this embodiment can upgrade a single communication loop to at least two independent and redundant communication loops for communicating with the converter valve submodule based on the interface unit, thereby effectively improving the utilization rate of the interface unit.

[0017] In this embodiment, the manner of setting a processing module corresponding to a normal communication loop in each interface board to a duty state includes: if the communication state of each communication loop is normal, setting any one processing module in each interface board to a duty state; If the communication status of some of the communication circuits is abnormal, a processing module corresponding to the communication circuit with normal communication status is set in each interface board as on-duty status; If the communication status of each communication loop is abnormal, then apply to switch another control unit to the duty state, so that the new control unit in the duty state can judge whether the communication loop of each communication aggregation board communicating with the converter valve submodule through the corresponding processing module is normal according to the communication status, and set a processing module corresponding to the communication loop with normal communication status in each interface board to the duty state. Specifically, if Figure 2 As shown, taking the A system control unit (i.e., a control unit in the valve control system) being in the duty state as an example, the method of setting a processor (i.e., a processing module) corresponding to a normal communication loop in each interface board to the duty state includes: 1) Taking the processors on the same interface board as an example (i.e., processor A and processor B on interface board 1 as an example), if the communication status of the two communication loops "control unit-communication summary board 1-processor A of interface board 1" and "control unit-communication summary board 2-processor B of interface board 1" are both normal (i.e., the communication status of each communication loop passing through interface board 1 is normal), then either processor A or processor B is set to the duty state on the interface board 1. In other embodiments, if there are more than two communication loops and their corresponding processors on the same interface board and these communication loops are all normal, then any one communication summary board is selected, and the processing modules corresponding to the communication summary board in the interface board are set to the duty state respectively.

[0018] Taking the processors on different interface boards as an example (i.e., processor A and processor B of interface board 1 and processor A and processor B of interface board 2 as an example), if the communication status of the two communication loops "control unit-communication summary board 1-processor A of interface board 1" and "control unit-communication summary board 2-processor B of interface board 1" are both normal, and the communication status of the two communication loops "control unit-communication summary board 1-processor A of interface board 2" and "control unit-communication summary board 2-processor B of interface board 2" are also normal (i.e., the communication status of each communication loop passing through interface board 1 and passing through interface board 2 is normal), then set either processor A or processor B on interface board 1 and interface board 2 to the duty state. For example, when processor A of interface board 1 is set to the duty state, the communication circuit of interface board 1 is control unit-communication summary board 1-interface board processor A; but when processor B of interface board 1 is set to the duty state, the communication circuit of interface board 2 is control unit-communication summary board 2-interface board processor B; interface board 1 and interface board 2 communicate using communication summary board 1 and communication summary board 2 respectively, and the communications between the two are independent of each other.

[0019] By using this method of independently setting a processor for each interface board instead of setting a single processor in batches (i.e., setting processor A for each interface board), not only can each interface board be set up with its own independent optional communication circuit, but each communication aggregation board also shares the communication pressure with each other, effectively improving the reliability of communication.

[0020] 2) Taking the processors on the same interface board as an example (i.e., processor A and processor B on interface board 1 as an example), if the communication loop of "control unit-communication summary board 1-processor A on interface board 1" is abnormal (i.e., the communication status of some communication loops in each communication loop is abnormal), taking this as an example, the processor B corresponding to the normal communication loop (i.e., the communication loop of "control unit-communication summary board 2-interface board processor B") is set to the duty state in the interface board. In other embodiments, if there are more than two communication loops and their corresponding processors set on each interface board, any one of the communication summary boards with normal communication loops is selected, and the processing modules corresponding to the communication summary board in each interface board are set to the duty state.

[0021] 3) Taking the processors on the same interface board as an example (i.e., processor A and processor B on interface board 1 as an example), if the communication status of the two communication loops of "control unit-communication summary board 1-processor A on interface board 1" and "control unit-communication summary board 2-processor B on interface board 1" are both abnormal (i.e., the communication status of each communication loop is abnormal), then an application is made to switch to the B system control unit (i.e., another control unit in the valve control system) as the duty state (the processors on different interface boards are independent of each other, so it is only necessary to satisfy that the communication status of the communication loops contained in the processors on one of the interface boards is abnormal to apply to switch to the other control unit in the valve control system as the duty state), so that the B system control unit in the duty state determines whether the communication loops through which each communication summary board (i.e., communication summary board 1 and communication summary board 2) communicates with the converter valve submodule through the corresponding processors (i.e., processor A and processor B) are normal according to the communication status, and a processor corresponding to a normal communication loop is set to the duty state in each interface board; if "control unit-communication summary board 1-interface board processor A" is normal, processor A is set to the duty state in each interface board. In other embodiments, if there are more than two control units and more than two communication loops and the processors set on their corresponding interface boards, an application is made to switch another control unit in the valve control system except the control unit to be on duty, so that the new control unit on duty can judge whether the communication loop through which each communication aggregation board communicates with the converter valve sub-module through its corresponding processor is normal according to the communication status, and select a communication aggregation board corresponding to the normal communication loop, and set a processing module corresponding to the communication aggregation board in each interface board to be on duty.

[0022] Embodiment of communication redundancy control method for direct current transmission valve control This embodiment provides a communication redundancy control method for direct current transmission valve control. The method determines whether the communication loop through which each communication aggregation board communicates with the converter valve submodule through the corresponding processing module is normal according to the communication state when the control unit of the direct current transmission valve control system is in the duty state, and sets the processing module corresponding to a normal communication loop in each interface board to the duty state, so as to forward the command of the control unit to the control end of the converter valve submodule through the processing module in the duty state; The valve control system includes an interface unit and at least two control units. The interface unit includes an interface board for accessing the corresponding control end of the converter valve submodule and at least two communication summary boards; the interface board includes processing modules that communicate with each communication summary board one-to-one; at most one of the control units is in a duty state; the communication summary board is used to send the communication state between itself and the corresponding processing module and the communication state between the corresponding processing module and the converter valve submodule to the control unit in the duty state.

[0023] Specifically, Figure 1 As shown, the communication summary board 1 of the interface unit summarizes the communication status between itself and all interface board processors A, and the communication status between each interface board processor A and the submodule central control board and sends it to the control unit; the communication summary board 2 of the interface unit summarizes the communication status with all interface board processors B, and the communication status between each interface board processor B and the submodule central control board and sends it to the control unit. A cross redundant communication method is adopted between the control unit and the interface unit, that is, each communication summary board of the interface unit communicates with the A and B system control units.

[0024] For each submodule central control board (i.e., the processing module corresponding to each interface board), it can be controlled through two communication loops: "control unit-communication summary board 1-interface board processor A" and "control unit-communication summary board 2-interface board processor B". The control unit in the duty state determines whether the communication state of the communication loop is normal based on the information uploaded by the communication summary board and the communication state of the communication summary board received by itself. According to the judgment result, a normal communication loop is selected, and the processor (i.e., processing module) corresponding to the normal communication loop is set to the duty state.

[0025] In this embodiment, the manner of setting a processing module corresponding to a normal communication loop in each interface board to a duty state includes: if the communication state of each communication loop is normal, setting any one processing module in each interface board to a duty state; If the communication status of some of the communication circuits is abnormal, a processing module corresponding to the communication circuit with normal communication status is set in each interface board as on-duty status; If the communication status of each communication loop is abnormal, an application is made to switch another control unit to the duty status, so that the new control unit in the duty status can judge whether the communication loop through which each communication summary board communicates with the converter valve sub-module through the corresponding processing module is normal according to the communication status, and set a processing module corresponding to the communication loop with normal communication status in each interface board to the duty status.

[0026] Specifically, Figure 2 As shown, taking the A system control unit (i.e., a control unit in the valve control system) being in the duty state as an example, the method of setting a processor (i.e., a processing module) corresponding to a normal communication loop in each interface board to the duty state includes: 1) Taking the processors on the same interface board as an example (i.e., processor A and processor B on interface board 1 as an example), if the communication status of the two communication loops "control unit-communication summary board 1-processor A of interface board 1" and "control unit-communication summary board 2-processor B of interface board 1" are both normal (i.e., the communication status of each communication loop passing through interface board 1 is normal), then either processor A or processor B is set to the duty state on the interface board 1. In other embodiments, if there are more than two communication loops and their corresponding processors on the same interface board and these communication loops are all normal, then any one communication summary board is selected, and the processing modules corresponding to the communication summary board in the interface board are set to the duty state respectively.

[0027] Taking the processors on different interface boards as an example (i.e., processor A and processor B of interface board 1 and processor A and processor B of interface board 2 as an example), if the communication status of the two communication loops "control unit-communication summary board 1-processor A of interface board 1" and "control unit-communication summary board 2-processor B of interface board 1" are both normal, and the communication status of the two communication loops "control unit-communication summary board 1-processor A of interface board 2" and "control unit-communication summary board 2-processor B of interface board 2" are also normal (i.e., the communication status of each communication loop passing through interface board 1 and passing through interface board 2 is normal), then set either processor A or processor B on interface board 1 and interface board 2 to the duty state. For example, processor A of interface board 1 is set to the duty state, and the communication circuit of interface board 1 is control unit-communication summary board 1-processor A of interface board 1; but processor B of interface board 2 is set to the duty state, and the communication circuit of interface board 2 is control unit-communication summary board 2-processor B of interface board 2; interface board 1 and interface board 2 use communication summary board 1 and communication summary board 2 respectively for communication, and the communications between the two are independent of each other.

[0028] By using this method of independently setting a processor for each interface board instead of setting a single processor in batches (i.e., setting processor A for each interface board), not only can each interface board be set up with its own independent optional communication circuit, but each communication aggregation board also shares the communication pressure with each other, effectively improving the reliability of communication.

[0029] 2) Taking the processors on the same interface board as an example (i.e., processor A and processor B on interface board 1 as an example), if the communication loop of "control unit-communication summary board 1-processor A on interface board 1" is abnormal (i.e., the communication status of some communication loops in each communication loop is abnormal), taking this as an example, another normal communication loop (i.e., the communication loop of "control unit-communication summary board 2-processor B on interface board 1") corresponding to processor B is set to the duty state in the interface board. In other embodiments, if there are more than two communication loops and their corresponding processors set on each interface board, select any one of the communication summary boards with a normal communication loop, and set the processing module corresponding to the communication summary board in each interface board to the duty state.

[0030] 3) Taking the processors on the same interface board as an example (i.e., processor A and processor B on interface board 1 as an example), if the communication status of the two communication loops of "control unit-communication summary board 1-processor A on interface board 1" and "control unit-communication summary board 2-processor B on interface board 1" are both abnormal (i.e., the communication status of each communication loop is abnormal), then an application is made to switch to the B system control unit (i.e., another control unit in the valve control system) as the duty state (the processors on different interface boards are independent of each other, so it is only necessary to satisfy that the communication status of the communication loops contained in the processors on one of the interface boards is abnormal to apply to switch to the other control unit in the valve control system as the duty state), so that the B system control unit in the duty state determines whether the communication loops through which each communication summary board (i.e., communication summary board 1 and communication summary board 2) communicates with the converter valve submodule through the corresponding processors (i.e., processor A and processor B) are normal according to the communication status, and a processor corresponding to a normal communication loop is set to the duty state in each interface board; if "control unit-communication summary board 1-interface board processor A" is normal, processor A is set to the duty state in each interface board. In other embodiments, if there are more than two control units and more than two communication loops and the processors set on their corresponding interface boards, an application is made to switch another control unit in the valve control system except the control unit to be on duty, so that the new control unit on duty can judge whether the communication loop through which each communication aggregation board communicates with the converter valve sub-module through its corresponding processor is normal according to the communication status, and select a communication aggregation board corresponding to the normal communication loop, and set a processing module corresponding to the communication aggregation board in each interface board to be on duty.

[0031] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, but do not constitute a limitation to the present invention.

Claims

1. A direct current transmission valve control system, characterized in that: It comprises an interface unit and at least two control units, wherein the interface unit comprises an interface board for accessing the corresponding control end of the converter valve submodule and at least two communication summary boards; the interface board comprises processing modules which communicate with each communication summary board one by one; at most one of the control units is in a duty state; the communication summary board is used to send the communication state between itself and the corresponding processing module and the communication state between the corresponding processing module and the converter valve submodule to the control unit in the duty state; the control unit is used to judge whether the communication loop through which each communication summary board communicates with the converter valve submodule through the corresponding processing module is normal according to the communication state in the duty state, and set a processing module corresponding to a normal communication loop in each interface board to the duty state, so as to forward the instruction of the control unit to the control end of the converter valve submodule through the processing module in the duty state.

2. The DC power transmission valve control system according to claim 1, characterized in that: The method of setting a processing module corresponding to a normal communication loop in each interface board to a duty state includes: if the communication state of each communication loop is normal, setting any processing module in each interface board to a duty state; If the communication status of some of the communication loops is abnormal, a processing module corresponding to the communication loop with normal communication status is set in each interface board as on-duty status; If the communication status of each communication loop is abnormal, an application is made to switch another control unit to the duty status, so that the new control unit in the duty status can judge whether the communication loop through which each communication summary board communicates with the converter valve sub-module through the corresponding processing module is normal according to the communication status, and set a processing module corresponding to the communication loop with normal communication status in each interface board to the duty status.

3. A communication redundancy control method for direct current transmission valve control, characterized in that: The control unit of the DC transmission valve control system determines whether the communication loop through which each communication aggregation board communicates with the converter valve submodule through the corresponding processing module is normal according to the communication state in the duty state, and sets a processing module corresponding to a normal communication loop in each interface board to the duty state, so as to forward the command of the control unit to the control end of the converter valve submodule through the processing module in the duty state; The valve control system includes an interface unit and at least two control units, the interface unit includes an interface board for accessing the corresponding control end of the converter valve submodule and at least two communication summary boards; the interface board includes processing modules that communicate with each communication summary board one-to-one; at most one of the control units is in a duty state; the communication summary board is used to send the communication state between itself and the corresponding processing module and the communication state between the corresponding processing module and the converter valve submodule to the control unit in the duty state.

4. The communication redundancy control method for direct current transmission valve control according to claim 3 is characterized in that: The method of setting a processing module corresponding to a normal communication loop in each interface board to a duty state includes: if the communication state of each communication loop is normal, setting any processing module in each interface board to a duty state; If the communication status of some of the communication loops is abnormal, a processing module corresponding to the communication loop with normal communication status is set in each interface board as on-duty status; If the communication status of each communication loop is abnormal, an application is made to switch another control unit to the duty status, so that the new control unit in the duty status can judge whether the communication loop through which each communication summary board communicates with the converter valve sub-module through the corresponding processing module is normal according to the communication status, and set a processing module corresponding to the communication loop with normal communication status in each interface board to the duty status.

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