A method for screening shared synchronization signals by combining synchronization and communication status

Abstract

The present invention proposes a method for combining synchronization and communication status to screen the synchronization signal for driving trigger pulses for an intelligent rectifier bridge that shares synchronization signals through an optical fiber network. When it is necessary to select drive synchronization, check whether the three-phase synchronization signals locally connected to the intelligent rectifier bridge are all normal, and the A-phase synchronization of the intelligent rectifier bridge that communicates normally with other intelligent rectifier bridges is normal; if all intelligent rectifier bridges have synchronization failures or communication failures between intelligent rectifier bridges, select the normal synchronization phase of the intelligent rectifier bridge with normal communication between intelligent rectifier bridges and synchronization single-phase failure; if all intelligent rectifier bridges have two-phase synchronization failures or lose contact with two intelligent rectifier bridges, select a normal one phase from the three-phase synchronization signals connected locally.

Description

Technical Field

[0001] The invention relates to the field of intelligent rectifier bridge control, and in particular to a method for combining synchronization and communication status to screen a shared synchronization signal. Background Art

[0002] The prior art proposes a high-redundancy synchronization method for an intelligent rectifier bridge based on FPGA and communication network (CN201910223958.X) and a method, system and medium for simultaneously transmitting data information and shared synchronization signals (CN202210663166.6). Figure 1 The method of sharing the synchronization signal of the intelligent rectifier bridge of the excitation system through a fiber optic network is shown in the invention patent A method for switching high-redundancy synchronization signals of an intelligent rectifier bridge (CN201911308805.1) proposes a method for accelerating fault judgment by comparing local synchronization and shared synchronization phases, but these patents do not consider the impact of communication network failures on shared synchronization technology.

[0003] In fact, transmitting synchronization signals through optical fiber networks will inevitably introduce network failures into the synchronization system. Figure 2 As shown, the intelligent rectifier bridge where the synchronization source is located With intelligent rectifier bridge Inter-communication interruption will cause the intelligent rectifier bridge The synchronization signal cannot be transmitted to the intelligent rectifier bridge , leading to intelligent rectifier bridge Zhongyuan Intelligent Rectifier Bridge The drive synchronization disappears. Intelligent rectifier bridge The A phase synchronization will be selected as the drive synchronization. However, according to the synchronization method published in CN201910223958.X, from the perspective of the control channel for executing external coordination, the intelligent rectifier bridge If the synchronization is normal and the serial number is the lowest, the intelligent rectifier bridge will still be specified. The A phase is synchronized as the drive synchronization, resulting in an intelligent rectifier bridge The drive synchronization switches repeatedly from the locally connected A-phase synchronization to no synchronization signal, and the overall output of the excitation system is unstable. Summary of the invention

[0004] The prior art also has the following problems: when obtaining a shared synchronization signal as a driving synchronization signal of a driving trigger pulse through a communication network, the driving synchronization signal is selected before the communication failure is determined, and it is inevitable to make an erroneous coordination selection, and it is easy to select the synchronization signal of the intelligent rectifier with a communication failure as the driving synchronization signal. To solve these problems, the technical solution of the present invention is:

[0005] A method for screening a driving synchronization signal in combination with synchronization and communication status, wherein the output ends of multiple intelligent rectifier bridges are connected in parallel, the intelligent rectifier bridges include a three-phase rectifier bridge, a controller configured with an FPGA and a CPU, the FPGA controllers of each intelligent rectifier bridge are point-to-point interconnected through independent optical fibers, the CPU queries the status of receiving optical fiber communication through the optical fiber from the data received from the FPGA, the intelligent rectifier bridge shares the locally accessed three-phase synchronization signal with other intelligent rectifier bridges through optical fiber communication, screens out one synchronization signal from the shared three-phase synchronization signal as the driving synchronization signal of the driving trigger pulse, the intelligent rectifier bridge simultaneously detects the status of the locally accessed three-phase synchronization signal and the driving synchronization signal, if the intelligent rectifier bridge detects that the driving synchronization signal fails, immediately sets a fault flag for the intelligent rectifier bridge providing the faulty synchronization signal, and reselects the driving synchronization after setting a refractory period; the remaining intelligent rectifier bridges set a refractory period and start to reselect the driving synchronization signal after receiving the message of the driving synchronization failure through the shared information:

[0006] Step 1: During the refractory period, the intelligent rectifier bridge without fault mark is included in the driving synchronization signal screening range, and the intelligent rectifier bridge with fault mark is excluded from the driving synchronization signal screening range, and the refractory period is greater than the difference between the optical fiber communication fault judgment delay and the synchronization signal fault judgment delay;

[0007] Step 2: From the set of intelligent rectifier bridges within the screening range of the drive synchronization signal, search for the locally connected A phase of the intelligent rectifier bridge with the smallest sequence number and no optical fiber communication failure with other intelligent rectifier bridges as the drive synchronization;

[0008] Step 3: If the intelligent rectifier bridge set is empty or all intelligent rectifier bridges in the searched intelligent rectifier bridge set have faults, including optical fiber communication faults and local access synchronization signal faults, then search for intelligent rectifier bridges that have no optical fiber communication faults with other intelligent rectifier bridges from all intelligent rectifier bridges with fault marks;

[0009] Step 4: If the smart rectifier bridge searched out in step 3 is not an empty set, then select the smart rectifier bridge whose locally connected three-phase synchronization signal has only a single-phase synchronization fault, and use the non-fault phase synchronization signal of the smart rectifier bridge with the smallest sequence number as the synchronous working phase;

[0010] Step 5: If the intelligent rectifier bridge searched out in step 3 is an empty set, search out the intelligent rectifier bridge having an optical fiber communication fault with only one other intelligent rectifier bridge from all intelligent rectifier bridges;

[0011] Step 6: If there is an intelligent rectifier bridge whose locally connected three-phase synchronization signals are all normal in the results searched in step 5, select the locally connected A phase of the intelligent rectifier bridge with the smallest serial number as the synchronous working phase; otherwise, select the intelligent rectifier bridge whose locally connected three-phase synchronization signal only has a single-phase synchronization fault, and use the non-fault phase synchronization signal of the intelligent rectifier bridge with the smallest serial number as the synchronous working phase;

[0012] Step 7: All intelligent rectifier bridges have optical fiber communication failures with at least two other intelligent rectifier bridges. The drive synchronization signal is directly selected from the locally connected three-phase synchronization signal, and the drive synchronization signal is not screened from the shared synchronization signal.

[0013] Furthermore, the refractory period is 1 second in length.

[0014] The step fault delay does not exceed 40ms, while the communication fault delay is about 200ms. The refractory period should not be less than 200-40=160ms. Considering fault tolerance, the refractory period is set to 1 second.

[0015] The synchronization fault delay is smaller than the communication fault delay. If the synchronization signal fault is caused by the communication fault, the intelligent rectifier bridge can be shielded outside the synchronization signal screening range before the communication fault is reported through the refractory period. After the communication fault is reported, the intelligent rectifier bridge is naturally shielded outside the synchronization signal screening range.

[0016] Furthermore, when the non-fault phase synchronization signal of the intelligent rectifier bridge is selected in steps 4 and 6, if an A-phase fault occurs in the intelligent rectifier bridge, the B-phase synchronization signal of the intelligent rectifier bridge is selected; if a B-phase fault occurs, the C-phase synchronization signal of the intelligent rectifier bridge is selected; if a C-phase fault occurs, the A-phase synchronization signal of the intelligent rectifier bridge is selected.

[0017] The beneficial effect of the present invention is that the present invention can solve the problem that the overall output of the excitation system is unstable when the network of the smallest numbered intelligent rectifier bridge and other intelligent rectifier bridges is interrupted. It also solves the problem that when obtaining a shared synchronization signal as a driving synchronization signal of a driving trigger pulse through a communication network, the driving synchronization signal is selected before the communication failure is determined, and it is inevitable to make an erroneous coordination selection, and it is easy to select the synchronization signal of the intelligent rectifier with a communication failure as the driving synchronization signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the implementation principle of the high redundancy synchronization technology in the prior art;

[0019] Figure 2 Schematic diagram of synchronization failure caused by communication failure (select intelligent rectifier bridge before communication failure) Phase A is used as the driving synchronization signal, and the intelligent rectifier bridge , After the optical fiber communication between them is accidentally interrupted, the intelligent rectifier bridge The synchronization signal cannot be transmitted to the intelligent rectifier bridge , leading to intelligent rectifier bridge Drive synchronization signal disappears));

[0020] Figure 3 For intelligent rectifier bridge , After the synchronization failure caused by the communication interruption between the two bridges, the online control channel coordinates the shared synchronization (assuming that the three-phase synchronization signal of each smart rectifier bridge is normal before the communication failure, and the communication with other smart rectifier bridges is normal, then the smart rectifier bridge , After the communication is interrupted, the intelligent rectifier bridge , Only with intelligent rectifier bridge , Communication is normal, intelligent rectifier bridge , At the same time, the communication with all intelligent rectifier bridges is normal because the intelligent rectifier bridge The serial number is low, so you should choose the smart rectifier bridge The synchronization source is due to the intelligent rectifier bridge The three-phase synchronous signal connected locally is normal, so the intelligent rectifier bridge is finally selected The A-phase synchronization signal is used as the driving synchronization signal of each intelligent rectifier bridge);

[0021] Figure 4 The process of selecting driving synchronization signals for the intelligent rectifier bridge;

[0022] Figure 5 It is the internal optical fiber communication network of the excitation system equipped with 4 intelligent rectifier bridges. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figure 1~Figure 2Taking the high-power power electronic device shown in the figure as an example, the output ends of multiple intelligent rectifier bridges are connected in parallel. The intelligent rectifier bridge includes a three-phase rectifier bridge, a controller equipped with FPGA and CPU, and the FPGA controllers of each intelligent rectifier bridge are interconnected point-to-point through two optical fibers for receiving and transmitting. Each optical fiber has its own independent optical fiber port. The FPGA controller is connected in parallel with different FPGA controllers through different optical fiber ports. A certain optical fiber port of the controller sending data and a certain optical fiber port of the controller receiving data are uniquely corresponding. The CPU queries the status of the optical fiber port receiving optical fiber communication from the data received from the FPGA.

[0025] The method for filtering a drive synchronization signal in combination with synchronization and communication status comprises the following steps:

[0026] S01. The intelligent rectifier bridge determines the status of the locally connected three-phase synchronization signal and the drive synchronization. If the intelligent rectifier bridge detects that a synchronization signal used for driving fails, a fault flag is immediately set for the intelligent rectifier bridge providing the faulty synchronization signal, and the status information of the synchronization signal and the status information of the intelligent rectifier bridge are shared with all intelligent rectifier bridges through the communication network. After receiving the shared information, the intelligent rectifier bridge sets a refractory period and then reselects the drive synchronization signal according to the principle of communication status first and the status of the locally connected three-phase synchronization signal second: when any intelligent rectifier bridge has a communication failure with at least two intelligent rectifier bridges, or when two phases of the locally connected three-phase synchronization signal of any intelligent rectifier bridge fail, the intelligent rectifier bridge is not included in the drive synchronization signal screening range;

[0027] S02. From the intelligent rectifier bridge within the driving synchronization signal screening range, priority is given to searching for intelligent rectifier bridges with no optical fiber communication failures and local access to three-phase synchronization signals without faults to form a set, and the local access phase A of the intelligent rectifier bridge with the smallest sequence number in the set is selected as the synchronous working phase;

[0028] S03. If the set is an empty set, from the intelligent rectifier bridge within the driving synchronization signal screening range, search for the intelligent rectifier bridge with no optical fiber communication failure with other intelligent rectifier bridges, and the local access three-phase synchronization signal only has a single-phase synchronization failure to form a set of two, and select the non-fault phase synchronization signal of the intelligent rectifier bridge with the smallest sequence number in the set two as the synchronous working phase;

[0029] S04. If the set 2 is an empty set, from the intelligent rectifier bridge within the driving synchronization signal screening range, search for only one other intelligent rectifier bridge with an optical fiber communication failure, and the local access three-phase synchronization signal is fault-free to form a set 3, and select the local access phase A of the intelligent rectifier bridge with the smallest sequence number in the set 3 as the synchronous working phase;

[0030] S05. If the set three is an empty set, from the intelligent rectifier bridge within the driving synchronization signal screening range, search for the intelligent rectifier bridge that has only one other intelligent rectifier bridge with an optical fiber communication failure, and the local access three-phase synchronization signal has only a single-phase synchronization failure to form a set four, and select the non-fault phase synchronization signal of the intelligent rectifier bridge with the smallest sequence number in the set four as the synchronous working phase;

[0031] If set four or the drive synchronization signal filtering range is an empty set, the drive synchronization signal is not filtered.

[0032] The above steps are also equivalent to the following steps:

[0033] Step 1, the intelligent rectifier bridge shares the locally accessed three-phase synchronization signal with other intelligent rectifier bridges through optical fiber communication, selects one synchronization signal from the shared three-phase synchronization signal as the driving synchronization signal of the driving trigger pulse, and the intelligent rectifier bridge simultaneously detects the status of the locally accessed three-phase synchronization signal and the driving synchronization signal. If the intelligent rectifier bridge detects that the driving synchronization signal fails, a fault flag is set for the intelligent rectifier bridge providing the faulty synchronization signal, and the status information of the synchronization signal and the intelligent rectifier bridge status information are shared with all intelligent rectifier bridges through the communication network; the remaining intelligent rectifier bridges immediately set a refractory period after receiving the shared information and start to reselect the driving synchronization signal; all intelligent rectifier bridges include the intelligent rectifier bridges without fault flags in the driving synchronization signal screening range during the refractory period, and exclude the intelligent rectifier bridges with fault flags from the driving synchronization signal screening range, and the refractory period duration is 1 second;

[0034] Step 2: from the set of intelligent rectifier bridges within the screening range of the driving synchronization signal, search for the locally connected A phase of the intelligent rectifier bridge with the smallest sequence number and no optical fiber communication failure with other intelligent rectifier bridges as the synchronous working phase;

[0035] For example Figure 2 In the example, it is assumed that the intelligent rectifier bridge ~Intelligent rectifier bridge If the three-phase synchronous signals connected locally are all fault-free, the four intelligent rectifier bridges are included in the drive synchronous signal screening range. And intelligent rectifier bridge There is a fiber optic communication failure, and the intelligent rectifier bridge And intelligent rectifier bridge When there is no optical fiber communication failure with other intelligent rectifier bridges, the intelligent rectifier bridge The serial number is the smallest, then the intelligent rectifier bridge The locally connected A phase is used as the synchronous working phase.

[0036] Step 3: If the set of intelligent rectifier bridges is empty or all intelligent rectifier bridges in the set of intelligent rectifier bridges are found to have faults (faults include optical fiber communication faults and local access synchronization signal faults), then search for intelligent rectifier bridges that have no optical fiber communication faults with other intelligent rectifier bridges from all intelligent rectifier bridges with fault marks;

[0037] For example Figure 2 In the example, it is assumed that the intelligent rectifier bridge And intelligent rectifier bridge The three-phase synchronous signals connected locally are all fault-free, but the intelligent rectifier bridge And intelligent rectifier bridge Optical fiber communication failure, intelligent rectifier bridge And intelligent rectifier bridge Single-phase synchronization faults occur in all four intelligent rectifier bridges, that is, all four intelligent rectifier bridges have fault signs, so the intelligent rectifier bridge without communication faults is selected. And intelligent rectifier bridge Do further screening. Intelligent rectifier bridge If the serial number is low and there is only a single-phase synchronous fault, the intelligent rectifier bridge should be selected The non-fault synchronous phase is used as the driving synchronization for all intelligent rectifier bridges.

[0038] Step 4: If the smart rectifier bridge searched out in step 3 is not an empty set, then select the smart rectifier bridge whose locally connected three-phase synchronization signal has only a single-phase synchronization fault, and use the non-fault phase synchronization signal of the smart rectifier bridge with the smallest sequence number as the synchronous working phase;

[0039] Step 5: If the intelligent rectifier bridge searched out in step 3 is an empty set, search out the intelligent rectifier bridge having an optical fiber communication fault with only one other intelligent rectifier bridge from all intelligent rectifier bridges;

[0040] Assumptions Figure 2 Intelligent rectifier bridge And intelligent rectifier bridge There is a communication failure, the intelligent rectifier bridge And intelligent rectifier bridge , Intelligent rectifier bridge And intelligent rectifier bridge If there is a communication failure, the intelligent rectifier bridge And intelligent rectifier bridge There is a fiber optic communication failure with only one other smart rectifier bridge because the smart rectifier bridge The serial number is low, so choose the intelligent rectifier bridge Non-fault synchronous phase intelligent rectifier bridge , , Drive synchronization, intelligent rectifier bridge No longer use the shared synchronization signal, you can exit the operation directly (if you do not exit, the local access synchronization signal will be selected as the drive synchronization, which is inconsistent with the synchronization signal of other intelligent rectifier bridges, which may affect the current sharing effect);

[0041] Step 6: If there is an intelligent rectifier bridge whose locally connected three-phase synchronization signals are all normal in the results searched in step 5, select the locally connected A phase of the intelligent rectifier bridge with the smallest serial number as the synchronous working phase, that is, the driving synchronization signal; otherwise, select the intelligent rectifier bridge whose locally connected three-phase synchronization signal only has a single-phase synchronization fault, and use the non-fault phase synchronization signal of the intelligent rectifier bridge with the smallest serial number as the driving synchronization signal;

[0042] Step 7: All intelligent rectifier bridges have optical fiber communication failures with at least two other intelligent rectifier bridges, and the drive synchronization signal is directly selected from the locally connected three-phase synchronization signal, and the drive synchronization signal is not selected from the shared synchronization signal obtained when sharing information in step 1;

[0043] like Figure 3 As shown in the figure, the delay of the synchronization signal fault judgment and the communication fault judgment in step 1 is different. If the shared synchronization signal obtained through the communication network is selected as the driving synchronization signal of the driving trigger pulse, then after the driving synchronization signal fails, the driving synchronization signal needs to be re-screened. In addition to avoiding the intelligent rectifier bridge that previously provided the synchronization signal, it should also maintain a period of non-response to the synchronization coordination of the online control channel after reselecting the driving synchronization signal. The non-response time is the refractory period.

[0044] like Figure 5 As shown in the figure, the excitation system is generally equipped with two control channels, one for online control and one for hot standby. It is used to respond to measurements, control calculations and processes. The control angle obtained by the control calculation is transmitted to each intelligent rectifier bridge through the optical fiber network to perform the bridge arm switch control of the phase-controlled rectification. The control channel also screens the shared synchronization signal according to the same steps to coordinate each intelligent rectifier bridge to make a consistent choice.

[0045] First, when the synchronization signal failure triggers the reselection of the drive synchronization signal, the intelligent rectifier bridge where the previous synchronization source is located is excluded from the selection range of the drive synchronization. In this way, if the synchronization failure is indeed caused by a communication failure, all synchronization signals of this intelligent rectifier bridge are unavailable, and the reselection of the drive synchronization will not make an incorrect choice; secondly, the refractory period can prevent the online control channel from making an incorrect coordination choice when no communication failure is detected.

[0046] Because the synchronization signal is only shared between smart rectifier bridges, only the communication status between smart rectifier bridges is checked, that is, how many smart rectifier bridges can a smart rectifier bridge communicate with normally. For example, in a system with 4 smart rectifier bridges, each smart rectifier bridge maintains normal communication with 4 smart rectifier bridges (including itself). If a smart rectifier bridge If the control module quits running (for example, the controller loses power and the module can no longer participate in communication), the other three intelligent rectifier bridges will have communication failures. Lost contact, only maintain normal communication with 3 smart rectifier bridges. With intelligent rectifier bridge If the communication line between them is disconnected, the intelligent rectifier bridge , Communication is completely normal, intelligent rectifier bridge , It only maintains normal communication with three intelligent rectifier bridges, among which the intelligent rectifier bridge The communication with smart rectifier bridges 1, 2, and 4 is normal, and the communication with smart rectifier bridge 3 is normal with smart rectifier bridges 1, 3, and 4. When synchronization failure and communication failure occur at the same time, the one with normal communication is preferred, because the disconnection of one phase of the synchronous PT can cause the phase shift of the two phases of the secondary side at most, and there is still one phase with normal phase that can be selected, while the interruption of communication means that not all smart rectifier bridges can select the same synchronization signal, which may have a negative impact on the current sharing effect.

[0047] Specifically, when the non-fault phase synchronization signal of the intelligent rectifier bridge is selected in step 4 and step 6, if the intelligent rectifier bridge has an A-phase fault, the B-phase synchronization signal of the intelligent rectifier bridge is selected, if the B-phase fault occurs, the C-phase synchronization signal of the intelligent rectifier bridge is selected, and if the C-phase fault occurs, the A-phase synchronization signal of the intelligent rectifier bridge is selected. Because the C-phase line break of the synchronous PT primary side will cause the B and C phases of the secondary side to be abnormal, and only the A-phase synchronization is normal; and the C-phase line break of the synchronous PT secondary side causes the C-phase synchronization signal to disappear, so when the C-phase synchronization fault is detected, one is switched to the A-phase synchronization signal, and a similar principle is used to select the normal synchronization phase when the remaining phases fail.

[0048] Specifically, in step 7, if the smart rectifier bridge with the best communication status also loses contact with at least two smart rectifier bridges, the shared synchronization technology is no longer possible, and the drive synchronization is directly selected from the locally connected three-phase synchronization signal.

Claims

1. A method for combining synchronization and communication status to filter a driving synchronization signal, wherein the output ends of a plurality of intelligent rectifier bridges are connected in parallel, the intelligent rectifier bridges include a three-phase rectifier bridge, an FPGA controller and a CPU, the FPGA controllers of each intelligent rectifier bridge are point-to-point interconnected through independent optical fibers, the CPU queries the status of receiving optical fiber communication through the optical fiber from the data received from the FPGA controller, each intelligent rectifier bridge shares a locally accessed three-phase synchronization signal with other intelligent rectifier bridges through optical fiber communication, a synchronization signal is filtered out from the shared three-phase synchronization signal as a driving synchronization signal for a driving trigger pulse, the intelligent rectifier bridge simultaneously detects the status of the locally accessed three-phase synchronization signal and the driving synchronization signal, and is characterized in that: If the intelligent rectifier bridge detects that the drive synchronization signal fails, it will immediately set a fault flag for the intelligent rectifier bridge that provides the faulty drive synchronization signal, set a refractory period and reselect the drive synchronization signal, and share the state information of the drive synchronization signal and the intelligent rectifier bridge state information with all intelligent rectifier bridges through the communication network; the remaining intelligent rectifier bridges will also set a refractory period and start to reselect the drive synchronization signal after receiving the shared information: Step 1: During the refractory period, the intelligent rectifier bridge without fault mark is included in the driving synchronization signal screening range, and the intelligent rectifier bridge with fault mark is excluded from the driving synchronization signal screening range, and the refractory period is greater than the difference between the optical fiber communication fault judgment delay and the synchronization signal fault judgment delay; Step 2: From the set of intelligent rectifier bridges within the driving synchronization signal screening range, search for the locally connected A-phase synchronization signal of the intelligent rectifier bridge with the smallest sequence number and no optical fiber communication failure with other intelligent rectifier bridges as the synchronization working phase; Step 3: If the intelligent rectifier bridge set is empty or all intelligent rectifier bridges in the searched intelligent rectifier bridge set have faults, including optical fiber communication faults and local access synchronization signal faults, then among all intelligent rectifier bridges with fault marks, search for intelligent rectifier bridges that have no optical fiber communication faults with other intelligent rectifier bridges; Step 4: If the smart rectifier bridge searched out in step 3 is not an empty set, then select the smart rectifier bridge whose locally connected three-phase synchronization signal has only a single-phase synchronization fault, and use the non-fault phase synchronization signal of the smart rectifier bridge with the smallest sequence number as the synchronous working phase; Step 5: If the intelligent rectifier bridge searched out in step 3 is an empty set, search out the intelligent rectifier bridge having an optical fiber communication fault with only one other intelligent rectifier bridge from all intelligent rectifier bridges; Step 6: If there is an intelligent rectifier bridge whose locally connected three-phase synchronization signals are all normal in the results searched in step 5, select the locally connected A-phase synchronization signal of the intelligent rectifier bridge with the smallest serial number as the synchronous working phase; otherwise, select the intelligent rectifier bridge whose locally connected three-phase synchronization signal only has a single-phase synchronization fault, and use the non-fault phase synchronization signal of the intelligent rectifier bridge with the smallest serial number as the synchronous working phase; Step 7: All intelligent rectifier bridges have optical fiber communication failures with at least two other intelligent rectifier bridges. The drive synchronization signal is directly selected from the locally connected three-phase synchronization signal, and the drive synchronization signal is not screened from the shared three-phase synchronization signal.

2. The method according to claim 1, characterized in that The refractory period duration is 1 second.

3. The method according to claim 1, characterized in that When the non-fault phase synchronization signal of the intelligent rectifier bridge is selected in step 4 and step 6, if the intelligent rectifier bridge has an A-phase fault, the B-phase synchronization signal of the intelligent rectifier bridge is selected, if a B-phase fault occurs, the C-phase synchronization signal of the intelligent rectifier bridge is selected, and if a C-phase fault occurs, the A-phase synchronization signal of the intelligent rectifier bridge is selected.

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