A flexible direct valve control system and communication redundancy control method

Abstract

The present invention belongs to the field of flexible direct current valve control, and specifically relates to a flexible direct current valve control system and a communication redundancy control method. The present invention sets link redundancy between communication nodes, solves the risk of system failure caused by a single link failure from the physical link layer, and causes system exit. In the event of a channel failure, the system is not directly switched, but the temporary failure of the channel is eliminated by restarting first, avoiding system switching caused by temporary failures that can be self-recovered by restarting, and reducing the system switching frequency; two priority reset methods are used, first restarting with less impact on the system and transmission process, and then the next restart method is performed if it is still not recovered after restarting, so that the channel recovery time and system disturbance can be reduced; and there is no priority for fault judgment and restart between two redundant channels, so that the failure of each channel can be eliminated as much as possible during the system operation, reducing the impact on the overall redundancy of the system.

Description

Technical Field

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

[0002] In recent years, high-voltage flexible direct current transmission has become an important transmission method for clean energy transmission such as west-to-east power transmission and offshore wind power transmission; and its share in the transmission field has increased year by year. Flexible direct current transmission has become an important part of my country's power grid. The flexible direct current converter valve and valve control system are the core equipment of the high-voltage flexible direct current transmission converter station, carrying the conversion function between AC and DC.

[0003] In the flexible DC transmission converter valve control system, within a compact monitoring cycle, all control instructions, control pulses, and sub-module states need to be transmitted through high-speed communication channels, so the reliability of communication channel transmission is required to be high; usually, the control strategy triggered by system failure is to exit the system and switch to the backup system. The switching process will cause system disturbances, while reducing the real-time performance of the system and affecting the control accuracy. In the existing valve control communication method, a link failure of any communication node will cause communication abnormalities and be judged as a system failure, so it will frequently trigger system switching, reducing the overall control efficiency of the valve control system. Summary of the invention

[0004] The object of the present invention is to provide a flexible direct valve control system and a communication redundancy control method, which are used to solve the problem in the prior art that the valve control communication mode frequently triggers system switching, resulting in low overall control efficiency of the valve control system.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a flexible direct current valve control communication redundant control method, the flexible direct current valve control includes a duty system, and two redundant channels are used between each communication node that needs to communicate inside the duty system. When a channel failure occurs, restart with a specified priority: when it is determined that a channel failure occurs in any channel, restart the control application layer corresponding to the channel; if the channel does not return to normal within the first set time after the restart, restart the physical link layer corresponding to the faulty channel.

[0006] The beneficial effects of the above technical solution are as follows: when a channel failure occurs, the communication redundancy control method does not directly perform system switching, but first eliminates the temporary failure of the channel by restarting, thereby avoiding system switching caused by temporary failures that can be self-recovered by restarting, and reducing the system switching frequency; and adopts two priority reset methods, first restarting the system and the transmission process with less impact, and then proceeding to the next restart method if it is still not recovered after restarting, thereby reducing the channel recovery time and system disturbance.

[0007] Further, when both redundant channels are normal, when it is determined that one of the channels is faulty and is restarted with the specified priority, if after the physical link layer is restarted, the communication of the channel has not returned to normal at the set time, it is determined that the channel has a permanent fault;

[0008] When only one of the two redundant channels is normal, when it is determined that the normal channel also fails and is restarted with the specified priority, if the communication of the channel does not return to normal after restarting the physical link layer, the channel is immediately determined to have a permanent failure.

[0009] The beneficial effect of the above technical solution is: when only one channel fails, this restart method can reserve a certain amount of time for the fault to be eliminated after the restart, avoiding directly determining that the channel has a permanent fault and causing a reduction in system redundancy. When both channels fail, the permanent fault is immediately determined, which can avoid the failure of data transmission caused by untimely dual-channel fault processing and the impact on system real-time performance.

[0010] Furthermore, the flexible direct current valve control also includes a backup system, and two redundant channels are also used between each communication node that needs to communicate within the backup system. If a permanent failure occurs in one of the two redundant channels of the duty system, the duty system exits and switches to the backup system for use; after the switch is completed, the control application layer of the two redundant channels of the duty system with permanent failure is restarted after a delay of a second set time. If the communication of a channel has not returned to normal within the first set time after the restart, the physical link layer corresponding to the channel that has not returned to normal is restarted.

[0011] Furthermore, if the duty system or the standby system has been out of use for a set time, the fault conditions of the two redundant channels between the communication nodes of the standby system are judged; when it is determined that both of the two redundant channels of the duty system or the standby system that are not in use have permanent faults, the control application layer of the two redundant channels of the system with permanent faults is immediately restarted; if a channel has not returned to normal within the first set time after the restart, the physical link layer corresponding to the channel that has not returned to normal is restarted.

[0012] Furthermore, the method for determining whether a channel is faulty is: timing from the moment when the channel starts to lose frames, and when the frame loss duration of a channel continues for a third set time, determining that the channel is faulty.

[0013] Furthermore, when communicating between communication nodes, redundant channel data selection is performed with a specified priority, the two redundant channels are a main channel and an auxiliary channel, and data received by the main channel or the auxiliary channel is selected as transmission data for subsequent communication.

[0014] The beneficial effect of the above technical solution is that it can make the links between communication nodes redundant, and solve the risk of system failure caused by a single link failure at the physical link layer, resulting in system exit.

[0015] Furthermore, the method of selecting redundant channel data is specifically as follows:

[0016] Starting from the moment when the upper communication of the two redundant channels of the communication node starts sending data, after a set time interval, if the main channel is normal, the data received by the main channel is selected as the sending data for subsequent communications; if the main channel fails and the auxiliary channel is normal, the data received by the auxiliary channel is selected as the sending data for subsequent communications; if both the main channel and the auxiliary channel fail, the data received by the last failed channel before the failure is maintained as the sending data for subsequent communications.

[0017] Furthermore, to avoid the situation where the channel does not complete data reception when redundant channel data is selected, the set time interval is greater than the time from the moment the upper-level communication of each redundant channel of the communication node starts sending data to the moment data reception is completed under normal communication.

[0018] The present invention also provides a flexible direct valve control system, including a duty system and a backup system, wherein the duty system and the backup system each include a plurality of communication nodes, and each communication node that needs to communicate uses two redundant channels to achieve communication redundancy between nodes;

[0019] The flexible direct current valve control system further includes a processor, and the processor is used to execute program instructions to implement the flexible direct current valve control communication redundant control method as described above.

[0020] The flexible direct-current valve control system can achieve the same beneficial effects as the flexible direct-current valve control communication redundant control method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a timing diagram of selecting redundant channel data in the embodiment of the flexible direct valve-controlled communication redundant control method of the present invention;

[0022] Figure 2 It is a specific flow chart of restarting with a specified priority in an embodiment of the flexible direct valve-controlled communication redundant control method of the present invention;

[0023] Figure 3 It is a communication redundancy architecture diagram of different levels of the flexible direct current valve control system in the embodiment of the flexible direct current valve control system of the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] Implementation example of a flexible direct valve control communication redundant control method:

[0026] This embodiment provides a technical solution for a flexible direct-current valve-controlled communication redundant control method, which is as follows:

[0027] Two redundant channels are used between each communication node that needs to communicate within the flexible direct valve control system. The two redundant channels are the main channel and the auxiliary channel. When communicating between communication nodes, redundant channel data selection is performed with a specified priority, and the data received by the main channel or the auxiliary channel is selected as the sending data for subsequent communication: starting from the moment when the upper communication of the two redundant channels of the communication node starts to send data, after a set time interval, if the main channel is normal, the data received by the main channel is selected as the sending data for subsequent communication; if the main channel fails and the auxiliary channel is normal, the data received by the auxiliary channel is selected as the sending data for subsequent communication; if both the main channel and the auxiliary channel fail, the data received by the last failed channel before the failure is kept as the sending data for subsequent communication. The above-mentioned set time interval is greater than the time from the moment when the upper communication of each redundant channel of the communication node starts to send data to the moment when data reception is completed under normal communication, that is, when selecting redundant channel data, it must be ensured that both the main channel and the auxiliary channel have completed data reception.

[0028] In this embodiment, refer to Figure 1 , the data transmission and synchronization relationship of the two channels between the communication nodes are completely consistent, and the communication synchronization period is recorded as t sys ; The time when the upper level communication of the two redundant channels of the communication node starts to send data is set to time 0, and the time after the set time interval is set to the data selection logic time, that is, time T3. When the channel completes data reception, a data frame reception completion flag will be generated; Taking various situations that may occur in the lower level communication process (in other embodiments, it can also be various node communication processes such as upper level sending communication or same level forwarding communication) as an example, the process of redundant channel data selection is as follows:

[0029] a. There are no faults in the main channel and the auxiliary channel, and data frame reception completion flags are generated in both channels; at time T3, the data received by the main channel is selected for sending data for lower-level communication.

[0030] b. The main channel fails, but the auxiliary channel is normal; a data frame reception completion flag is generated on the auxiliary channel; at time T3, the data received by the auxiliary channel is selected for sending data for lower-level communication.

[0031] c. The main channel is normal, and the auxiliary channel is faulty; a data frame reception completion flag is generated on the main channel; at time T3, the data received by the main channel is selected for sending data for lower-level communication.

[0032] d. Both the main channel and the auxiliary channel fail; no data frame reception completion flag is generated in either channel; at time T3, the data received by the last failed channel is kept for sending data for lower-level communication.

[0033] e. Both the main channel and the auxiliary channel fail, and any channel failure is restored before T3; a data frame reception completion flag is generated before T3; at T3, the transmission data used for lower-level communication is restored to the selection mode when the channels are not completely faulty in the above a.-c. situations.

[0034] The data frame of the main channel is sent from time 0 and is received at time T1; the data frame of the auxiliary channel is sent from time 0 and is received at time T2; the time difference between T1 and T2 caused by the physical link and clock deviation between the main channel and the auxiliary channel is t Δ , then the time interval t from the effective reception completion flag of any channel to the data selection logic time T3 1 Greater than t Δ ; Here the time interval t1>t Δ The purpose of this setting is to ensure that when data is sent at time T3, the main channel and the auxiliary channel can reliably complete data reception.

[0035] In this embodiment, the method of determining whether a channel has a fault is: starting from the moment when the channel starts to lose frames, when the frame loss duration of a channel continues for a third set time, the channel is determined to have a fault. In this embodiment, the third set time is recorded as the channel temporary fault judgment time t err .

[0036] In order to avoid permanent failure of channels, reduce the situation where channels lose redundancy due to recoverable failures, and combine with inter-system switching to maximize the redundancy of the system, when a channel failure occurs, the system will not switch, but will be restarted with the specified priority: when a channel failure is determined in any channel, the control application layer corresponding to the channel will be restarted; if the channel does not return to normal within the first set time after the restart, the physical link layer corresponding to the faulty channel will be restarted. For the main channel and auxiliary channel between any two communication nodes in a single system, the channel failure restart logic has no priority, and the logic will be restarted for any channel failure.

[0037] The specific restart method is: when both redundant channels are normal, if one of the channels is determined to be faulty, restart the control application layer corresponding to the faulty channel; if the communication of the channel does not return to normal within the first set time after the restart, restart the physical link layer corresponding to the faulty channel; if after restarting the corresponding physical link layer, the communication of the channel still does not return to normal when the set time is reached, it is determined that the channel has a permanent fault;

[0038] When only one of the two redundant channels is normal, when it is determined that the normal channel is also faulty, restart the control application layer corresponding to the channel; if the channel does not return to normal within the first set time after the restart, restart the physical link layer corresponding to the faulty channel; if the communication of the channel does not return to normal after restarting the corresponding physical link layer, immediately determine that the channel has a permanent fault.

[0039] When only one channel fails, the above restart method can reserve a certain amount of time for the fault to be eliminated after the restart, avoiding directly determining that the channel has a permanent fault and causing a reduction in system redundancy. When both channels fail, permanent faults are immediately determined, which can avoid data transmission failure caused by untimely dual-channel fault processing and affect the real-time performance of the system.

[0040] In this embodiment, two redundant link channels are also used between each communication node of the backup system of the flexible direct current valve control. The system used under normal circumstances is called the duty system, and the system used for switching into operation after the duty system exits due to a fault is called the backup system; therefore, the restart method for restarting with a specified priority also includes the following strategies: if both channels of the duty system have permanent faults, the duty system exits and switches to the backup system; after the switching is completed, the control application layer of the dual channels of the duty system is restarted after a delay of a second set time, and if the communication of a channel has not returned to normal within the first set time after the restart, the physical link layer corresponding to the channel that has not returned to normal is restarted.

[0041] If it is determined that both channels of the backup system have permanent faults, the control application layer of the dual channels will be restarted immediately; if any channel has not recovered within the first set time after the restart, the physical link layer corresponding to the channel that has not recovered will be restarted.

[0042] In this embodiment, when the channel starts to lose frames, the permanent fault judgment time count starts, and the time interval between the set time and the time when the channel starts to lose frames is recorded as the channel permanent fault judgment time t merr ; The first set time is recorded as the channel fault recovery judgment time t su ; The system operation tolerance time when the system internal communication fails is recorded as t max , the tolerance time t maxIt is the maximum time that the converter valve is uncontrollable due to the internal channel failure of the valve control system, but does not cause overvoltage or overcurrent. If it is longer than this time, the converter valve will trip due to overvoltage or overcurrent. The second set time is recorded as the delay time t for restarting the physical link layer after completing the switching. d ; According to various situations that may occur during the communication process, Figure 2 As shown in the figure, the overall process of restarting with a specified priority is as follows:

[0043] ① When there is no fault in the communication channel, no channel fault restart is performed;

[0044] ② When both communication channels are normal, take the case where the main channel changes from normal to faulty and the auxiliary channel is normal as an example (during the main channel fault, data transmission continues through the non-faulty auxiliary channel):

[0045] When the frame loss time of the main channel reaches the temporary fault judgment time t err When the control application layer is restarted immediately.

[0046] Recovery judgment time t after restarting the control application layer of the main channel su If the main channel fault is restored, the physical link layer will not be restarted, and the permanent fault judgment time count will be reset; if the communication fault is not restored, the physical link layer will be restarted. If the communication channel fault is restored, the permanent fault judgment time count will be reset; if the channel fault time reaches the permanent fault judgment time t merr , the main channel generates a channel permanent fault flag.

[0047] ③When only one of the two communication channels is normal, take the case where the main channel fails and the auxiliary channel changes from normal to fault as an example:

[0048] When the auxiliary channel frame loss time reaches t err When the auxiliary communication channel is restarted, the control application layer is restarted immediately.

[0049] Recovery judgment time t after restarting the control application layer of the auxiliary channel su If the auxiliary channel fault is restored, the physical link layer will not be restarted and the permanent fault judgment time count will be reset; if the communication fault is not restored, the channel permanent fault flag will be generated immediately.

[0050] If both redundant channels of the on-duty system have permanent fault signs, apply for system switching. After the system exits and switches to the backup system, the delay t d After the time, the physical link layer and control application layer of the two redundant channels of the duty system with permanent failure are restarted again. After restarting the control application layer corresponding to the channel, each redundant channel will go through the recovery judgment time t suIf the channel fault is restored within the recovery judgment time, the physical link layer corresponding to the channel will not be restarted; if it is not restored, the physical link layer corresponding to the channel will continue to be restarted. After the channel fault is restored, the channel permanent fault flag of the channel is cancelled and the channel remains available. When a dual-channel permanent fault occurs in the backup system, the system can be switched back to the duty system. In this embodiment, the method of switching back to the duty system when a dual-channel permanent fault occurs in the backup system is the same as the method of switching the duty system to the backup system.

[0051] If the on-duty system exits or the standby system has been in standby state for a set time, that is, the on-duty system or the standby system has not been put into use, the fault status of the two redundant channels between the communication nodes of the on-duty system or the standby system that has not been put into use will be judged in real time; if the on-duty system or the standby system that has not been put into use has two redundant channels with permanent fault marks, the control application layer corresponding to the two redundant channels of the system with permanent faults will be restarted immediately. After restarting the control application layer corresponding to the channel, each redundant channel will go through the recovery judgment time t su If the channel fault is restored within the recovery judgment time, the physical link layer corresponding to the channel will not be restarted; if it is not restored, the physical link layer corresponding to the channel will continue to be restarted; for the duty system that has not been put into use, the above-mentioned restart logic after the duty system exits the switch will no longer be executed, and the same applies to the backup system that has not been put into use; thereby ensuring that when one of the systems is put into operation, the replacement system is kept as fault-free as possible, so that when the running system fails, it can be switched in time and put into a fault-free replacement system to continue to maintain the system function, avoiding the situation where both the running system and the replacement system fail, resulting in the failure of the flexible direct valve control. After the channel fault is restored, the channel permanent fault flag of the channel is cancelled and kept in an available state. When a dual-channel permanent fault occurs in the duty system, it can be switched back to the backup system.

[0052] Soft straight valve control system example:

[0053] This embodiment provides a technical solution for a flexible direct valve control system. Figure 3As shown, the flexible direct current valve control system mainly includes three levels, namely, the converter valve submodule interface layer, the bridge arm control application layer, and the system control. Data is transmitted between the levels through multiple communication nodes; the converter valve submodule interface layer is connected to the bridge arm control application layer through the corresponding communication node, and the bridge arm control application layer is connected to the valve control system control application layer through the corresponding communication node; the converter valve submodule interface is located inside the control box, and the submodule interface card is connected to the data aggregation card through the corresponding communication node; two redundant channels, namely, the main channel and the auxiliary channel, are used between each communication node that needs to communicate inside the valve control system to achieve communication redundancy between nodes; the valve control system also includes a duty system and a backup system, and two redundant channels are used between each communication node inside the duty system and the backup system to achieve overall redundancy of the valve control system.

[0054] The flexible direct current valve control system further includes a processor, and the processor is used to execute program instructions to implement a control method as described in the flexible direct current valve control communication redundant control method embodiment.

[0055] The present invention has the following characteristics:

[0056] 1) The present invention sets up link redundancy between communication nodes to solve the risk of system failure caused by a single link failure and system exit from the physical link layer;

[0057] 2) When a channel failure occurs, the present invention does not directly switch the system, but first eliminates the temporary failure of the channel by restarting, avoiding system switching caused by temporary failures that can be self-recovered by restarting, and reducing the frequency of system switching; and adopts two priority reset methods, first restarting the system and the transmission process with less impact, and then performing the next restart method if there is still no recovery after restart, thereby reducing the channel recovery time and system disturbance; and there is no priority in fault judgment and restart between the two redundant channels, so that the failure of each channel can be eliminated as much as possible during the operation of the system, reducing the impact on the overall redundancy of the system.

[0058] 3) When only one channel fails, the restart method of the present invention can reserve a certain amount of time for the fault to be eliminated after the restart, thereby avoiding the reduction of system redundancy due to direct determination of permanent fault of the channel. When both channels fail, permanent faults are immediately determined, thereby avoiding the failure of data transmission due to untimely handling of dual-channel faults, thereby affecting the real-time performance of the system.

[0059] 4) The present invention still restarts the duty system after the duty system exits, so it can timely discover whether the fault of the duty system has been restored, so that the duty system that has restored the fault can be used for switching when the backup system fails, reducing the impact on the overall redundancy of the system.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A flexible direct valve control communication redundancy control method, characterized in that: The valve control system includes a duty system and a backup system. Both the duty system and the backup system include multiple communication nodes. Two redundant channels are used between each communication node to achieve communication redundancy between nodes. When a channel failure occurs in a two-way redundant channel in the duty system, it is restarted with a specified priority: when it is determined that a channel failure occurs in any channel, the control application layer corresponding to the channel is restarted; If the channel does not return to normal within the first set time after restart, restart the physical link layer corresponding to the faulty channel; In the case where both redundant channels are normal, when it is determined that one of the channels is faulty and is restarted with the specified priority, if after the physical link layer is restarted, the communication of the channel has not returned to normal at the set time, it is determined that the channel has a permanent fault; When only one of the two redundant channels is normal, when it is determined that the normal channel also fails and is restarted with the specified priority, if the communication of the channel does not return to normal after restarting the physical link layer, the channel is immediately determined to have a permanent failure.

2. The flexible direct valve control communication redundancy control method according to claim 1 is characterized in that: If permanent failure occurs in two redundant channels of the duty system, the duty system will exit and switch to the backup system for use; after the switch is completed, the control application layer of the two redundant channels of the duty system with permanent failure will be restarted after a delay of the second set time. If the communication of any channel has not returned to normal within the first set time after the restart, the physical link layer corresponding to the channel that has not returned to normal will be restarted.

3. The flexible direct valve control communication redundancy control method according to claim 2 is characterized in that: If the duty system or the standby system is not in use for a set time, the fault condition of the two redundant channels between the communication nodes of the standby system will be determined; when it is determined that a permanent fault occurs in one of the two redundant channels of the duty system or the standby system that is not in use, the control application layer of the two redundant channels of the system with the permanent fault will be restarted immediately; If there is a channel that has not recovered within the first set time after the restart, the physical link layer corresponding to the channel that has not recovered is restarted.

4. The flexible direct valve control communication redundancy control method according to any one of claims 1 to 3, characterized in that: The method of determining whether a channel is faulty is as follows: timing is started from the moment when the channel starts to lose frames, and when the frame loss duration of a channel continues for a third set time, it is determined that the channel is faulty.

5. The flexible direct valve control communication redundancy control method according to any one of claims 1 to 3, characterized in that: When communicating between communication nodes, redundant channel data selection is performed with a specified priority. The two redundant channels are the main channel and the auxiliary channel. The data received by the main channel or the auxiliary channel is selected as the sending data for subsequent communication.

6. The flexible direct valve control communication redundancy control method according to claim 5, characterized in that: The specific method of selecting redundant channel data is as follows: From the moment when the upper communication of the two redundant channels of the communication node starts to send data, after a set time interval, if the main channel is normal, the data received by the main channel is selected as the sending data for subsequent communications; If the main channel fails and the auxiliary channel is normal, the data received by the auxiliary channel is selected as the sending data for subsequent communications; if both the main channel and the auxiliary channel fail, the data received by the last failed channel before the failure is kept as the sending data for subsequent communications.

7. The flexible direct valve control communication redundancy control method according to claim 6, characterized in that: The set time interval is greater than the duration from the moment when the upper level communication of each redundant channel of the communication node starts sending data to the moment when data reception is completed under normal communication conditions.

8. A flexible direct current valve control system, the flexible direct current valve control system further comprising a processor, the processor being used to execute program instructions to implement communication redundancy control according to the flexible direct current valve control communication redundancy control method as described in any one of claims 1 to 7 above.

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