A chain-type multi-branch differential protection synchronization method and system

Abstract

The present invention discloses a chained multi-branch differential protection synchronization method and system. A differential protection device is pre-installed at each node along the entire trunk network, and each differential protection device is connected in a chained communication manner. The system obtains the power grid line communication status between the differential protection devices at all nodes along the trunk network. If the communication status between the differential protection devices in all power grid lines is normal, a master-slave determination is performed based on a pre-set master-slave determination rule. Data synchronization is performed based on the determination result using a pre-set data synchronization mechanism. If the communication status between the differential protection devices at both end nodes of a certain section of the power grid lines is abnormal, data synchronization is performed based on a pre-set communication anomaly handling mechanism. Advantages: The system has good adaptability to communication anomalies such as channel interruptions or anomalies, optical fiber connection errors, and improves the power supply reliability of medium and low voltage distribution networks.

Description

Technical Field

[0001] The present invention relates to a chain-type multi-branch differential protection synchronization method and system, belonging to the technical field of power system transmission line relay protection. Background Art

[0002] Medium and low voltage distribution networks typically utilize radial lines or interconnect the ends of radial lines to form a hand-in-hand dual-power ring network. Short line distances, a large number of cascaded switches, and the influx of distributed generation (DG) make the grid a complex, multi-power network, and energy flow is no longer unidirectional. Traditional current protection in medium and low voltage distribution systems is essentially a standalone unit protection system. It only detects the current flowing through the monitored switch to determine whether the protection is activated and the delay, without considering the protection of adjacent switches. This is the main reason for the difficulty in coordinating adjacent protection systems. This method is extremely difficult to isolate faults and is no longer suitable for modern distribution networks.

[0003] In the medium and low voltage power grid scenarios with large-scale distributed power generation, it is difficult to achieve rapid and accurate identification of fault sections by relying solely on simple overcurrent principles. It is imperative to adopt a multi-point information comparison method with absolute selectivity. Longitudinal differential protection makes full use of communication channels to expand the scope of information collection. It has the advantages of sensitivity, reliability, and fast action speed. It can also adapt to various complex fault operating conditions and effectively improve the protection level of the power grid.

[0004] Differential protection requires a sampling synchronization process. Existing fiber-optic differential protection typically uses a sampling time adjustment method to achieve synchronous sampling on both sides. Information is exchanged synchronously between the two sides, with a fixed sampling interval at the reference end and a fixed frame of information sent to the opposite end during each sampling interval. The synchronization end adjusts the sampling interval at any time until synchronization conditions are met. However, this method is only applicable to two-terminal single-branch line protection. It is no longer applicable to chained multi-branch line protection, which is common in medium and low voltage distribution networks and requires synchronous sampling with line protection on both sides. Therefore, a differential protection synchronization method for chained multi-branch lines is urgently needed to address these technical issues. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a chain-type multi-branch differential protection synchronization method and system.

[0006] To solve the above technical problems, the present invention provides a chained multi-branch differential protection synchronization method, comprising:

[0007] A set of differential protection devices is pre-installed at each node along the entire line backbone network, and each differential protection device is connected in a chain communication manner;

[0008] Obtain the power grid line communication status between differential protection devices at all nodes along the entire backbone network;

[0009] If the communication status between the differential protection devices in all power grid lines is normal, the master-slave judgment is performed according to the preset master-slave judgment rule, and data synchronization is performed according to the preset data synchronization mechanism based on the judgment result;

[0010] If the communication status between the differential protection devices at the two end nodes of a certain section of the power grid is abnormal, data synchronization is performed according to a preset communication abnormality handling mechanism.

[0011] Furthermore, the nodes include: the transformer substation outlets at both ends of the line and the ring network cabinets or switchgears.

[0012] Furthermore, the differential protection devices are connected in a chain communication manner, including:

[0013] The differential protection device is equipped with dual optical fiber channels for differential protection data exchange, corresponding to channel A and channel B;

[0014] Establish communication between channel A of each differential protection device and channel B of the upper differential protection device at the opposite end of the same line section;

[0015] Establish communication between the channel B of each differential protection device and the channel A of the lower differential protection device at the opposite end of the same line section.

[0016] Furthermore, the obtaining of the power grid line communication status between the differential protection devices at all nodes of the entire backbone network includes:

[0017] Each differential protection device is set with a local identification code, a channel A opposite side identification code, and a channel B opposite side identification code. The local identification code, the channel A opposite side identification code, and the channel B opposite side identification code are protection set values, and the communication status of each section of the power grid is determined by comparing the identification codes.

[0018] Furthermore, the determining of the communication status of each section of the power grid by comparing identification codes includes:

[0019] The opposite identification code of channel A of each differential protection device is set to the local identification code of the opposite differential protection device corresponding to channel A of the differential protection device; the opposite identification code of channel B of each differential protection device is set to the local identification code of the opposite differential protection device corresponding to channel B of the differential protection device;

[0020] Each differential protection device receives the identification code of the corresponding opposite protection device through its channel A and compares it with the identification code of the opposite side of channel A. If the two identification codes are consistent, the status of channel A of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel A of the differential protection device is abnormal.

[0021] Each differential protection device receives the identification code of the corresponding opposite protection device through its channel B and compares it with the identification code of the opposite side of channel B. If the two identification codes are consistent, the status of channel B of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel B of the differential protection device is abnormal.

[0022] For the differential protection devices at both ends of a certain line section, if the status of channel B of the upper differential protection device and channel A of the lower differential protection device are both normal, the communication status between the two differential protection devices is normal; otherwise, the communication status of this line section is abnormal.

[0023] Furthermore, the master-slave determination rule includes:

[0024] The differential protection device obtains the maximum channel identification code of all upper-level differential protection devices through channel A, compares the local identification code with the maximum channel identification code of all upper-level protection devices, and transmits the larger value to the lower-level differential protection device through channel B. At the same time, the differential protection device obtains the maximum channel identification code of all lower-level protection devices through channel B, compares the local identification code with the maximum channel identification code of all lower-level protection devices, and transmits the larger value to the upper-level differential protection device through channel A.

[0025] Until the maximum channel identification code of the differential protection device on the entire line is compared, the differential protection device corresponding to the one with the largest local identification code on the entire line is determined to be the master. The master on the entire line is unique, and the remaining devices are slaves.

[0026] Furthermore, the data synchronization mechanism includes:

[0027] The slaves adjacent to the master first synchronize with the master, calculate the channel delay with the master, and then synchronize according to the sampling time adjustment method;

[0028] For slaves that are not adjacent to the master, set the slaves adjacent to the master as pseudo-masters, calculate the channel delay with the pseudo-master, and then synchronize them according to the sampling time adjustment method; and so on, until the sampling synchronization is completed on the entire line.

[0029] Furthermore, the communication exception handling mechanism includes:

[0030] After identifying the abnormal channel in channel A or channel B between the devices at both ends of each section of the line, the corresponding device will issue a communication abnormality alarm signal and exit the abnormal section differential protection;

[0031] For each segment without communication anomalies, the internal differential protection device still redefines the relationship between the master and slave machines based on the master-slave determination rule, and resynchronizes data based on the data synchronization mechanism.

[0032] A chain-type multi-branch differential protection synchronization system, comprising:

[0033] A setting module is used to pre-install a set of differential protection devices at each node along the entire line backbone network, and each differential protection device is connected in a chain communication manner;

[0034] An acquisition module is used to obtain the power grid line communication status between the differential protection devices at all nodes of the entire backbone network;

[0035] The determination module is used to perform master-slave determination according to a preset master-slave determination rule if the communication status between the differential protection devices in all power grid lines is normal, and perform data synchronization according to a preset data synchronization mechanism based on the determination result; if the communication status between the differential protection devices at the two end nodes of a certain section of line in all power grid lines is abnormal, perform data synchronization according to a preset communication abnormality handling mechanism.

[0036] Furthermore, the nodes include: the transformer substation outlets at both ends of the line and the ring network cabinets or switchgears.

[0037] Furthermore, the differential protection devices are connected in a chain communication manner, including:

[0038] The differential protection device is equipped with dual optical fiber channels for differential protection data exchange, corresponding to channel A and channel B;

[0039] Establish communication between channel A of each differential protection device and channel B of the upper differential protection device at the opposite end of the same line section;

[0040] Establish communication between the channel B of each differential protection device and the channel A of the lower differential protection device at the opposite end of the same line section.

[0041] Furthermore, the acquisition module is used to set a local identification code, a channel A opposite side identification code and a channel B opposite side identification code for each differential protection device, and the local identification code, the channel A opposite side identification code and the channel B opposite side identification code are protection constants, and the communication status of each section of the power grid line is determined by comparing the identification codes.

[0042] Furthermore, the acquisition module is used to

[0043] The opposite side identification code of channel A of each differential protection device is set to the local identification code of the opposite side differential protection device corresponding to channel A of the differential protection device, and the opposite side identification code of channel B of each differential protection device is set to the local identification code of the opposite side differential protection device corresponding to channel B of the differential protection device;

[0044] Each differential protection device receives the identification code of the corresponding opposite protection device through its channel A and compares it with the identification code of the opposite side of channel A. If the two identification codes are consistent, the status of channel A of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel A of the differential protection device is abnormal.

[0045] Each differential protection device receives the identification code of the corresponding opposite protection device through its channel B and compares it with the identification code of the opposite side of channel B. If the two identification codes are consistent, the status of channel B of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel B of the differential protection device is abnormal.

[0046] For the differential protection devices at both ends of a certain line section, if the status of channel B of the upper differential protection device and channel A of the lower differential protection device are both normal, the communication status between the two differential protection devices is normal; otherwise, the communication status of this line section is abnormal.

[0047] Furthermore, the determination module is used to

[0048] The control differential protection device obtains the maximum channel identification code of all upper differential protection devices through channel A, compares the local identification code with the value of the maximum channel identification code of all upper protection devices, and transmits the larger value to the lower differential protection device through channel B; at the same time, the differential protection device obtains the maximum channel identification code of all lower protection devices through channel B, compares the local identification code with the value of the maximum channel identification code of all lower protection devices, and transmits the larger value to the upper differential protection device through channel A; until the comparison of the maximum channel identification codes of the differential protection devices of the entire line is completed, it is determined that the differential protection device corresponding to the one with the largest local identification code of the protection devices of the entire line is the master, the master is unique for the entire line, and the remaining devices are slaves.

[0049] Furthermore, the determination module is used to

[0050] The slaves adjacent to the master are first synchronized with the master, and the channel delay with the master is calculated, and then synchronization is performed according to the sampling time adjustment method; for the slaves not adjacent to the master, the slaves adjacent to the master are set as pseudo-masters, and the channel delay with the pseudo-master is calculated, and then synchronization is performed according to the sampling time adjustment method; and so on, until sampling synchronization is completed along the entire line.

[0051] Furthermore, the determination module is used to

[0052] After determining that the channel A or channel B between the devices at both ends of each section of the line is in an abnormal state, the corresponding device will issue a communication abnormality alarm signal and exit the abnormal section differential protection; for each section without communication abnormality, the internal differential protection device will still redetermine the master-slave relationship based on the master-slave judgment rules, and re-synchronize data based on the data synchronization mechanism.

[0053] A computer-readable storage medium storing one or more programs, the one or more programs comprising instructions that, when executed by a computing device, cause the computing device to perform any of the methods described.

[0054] A computing device comprising:

[0055] One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any of the methods described.

[0056] The beneficial effects achieved by the present invention are:

[0057] The present invention proposes new master-slave determination rules, data synchronization mechanism and communication anomaly processing mechanism, which requires less wiring at the protection device port and is low in cost. It can realize the segmented operation of chain multi-branch power grid line differential protection, has good adaptability to communication anomalies such as channel interruption or anomaly, optical fiber connection error, etc., and improves the power supply reliability of medium and low voltage distribution networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a schematic diagram of the deployment of two differential protection devices under the ring network architecture when all channels between substation A and substation B are operating normally and soundly;

[0059] Figure 2 It is a chain multi-branch differential synchronization flow chart;

[0060] Figure 3 This is a schematic diagram of the operation of the differential protection device when an interruption or abnormality occurs somewhere in the entire line channel between substation A and substation B in a ring network architecture;

[0061] Figure 4 This is a schematic diagram of the operation of the differential protection device when an optical fiber connection error occurs somewhere in the entire line channel between substation A and substation B in a ring network architecture. DETAILED DESCRIPTION

[0062] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0063] like Figure 1 As shown, the present invention provides a chained multi-branch differential protection synchronization method, comprising:

[0064] 1) A differential protection device is installed at each node along the entire power grid line;

[0065] The differential protection devices at both ends of the line respectively collect the voltage and current analog values and switching values at the line outlets of the corresponding substations at both ends. The differential protection device S1 at the line head end collects the voltage and current analog values and switching values at the substation A line L1. The differential protection device S5 at the line end collects the voltage and current analog values and switching values at the substation B line L8.

[0066] The differential protection devices at the other intermediate nodes simultaneously collect the analog voltage and current values as well as the switching values at the incoming and outgoing lines of the corresponding ring network cabinets and switchgear.

[0067] 2) Each differential protection device is equipped with two independent optical fiber communication interfaces, corresponding to channel A and channel B respectively. The interfaces of each differential protection device are connected by optical fiber in a chain communication mode;

[0068] 3) Each differential protection device is equipped with a local identification code, a channel A opposite side identification code, and a channel B opposite side identification code. These three identification codes are protection settings, and the communication status of the power grid line is determined by comparing the identification codes.

[0069] 4) If the communication status between the differential protection devices at all nodes at both ends of the power grid line is normal, each differential protection device determines the master and slave according to the master-slave determination rule. If the slave is not adjacent to the master, an adjacent slave is determined as a pseudo-master.

[0070] 5) Adjacent differential protection devices must synchronize data according to the master and slave device judgment results and the data synchronization mechanism;

[0071] 6) If there is a line in all power grid lines where the communication status between the differential protection devices at the nodes at both ends of the line is abnormal, the communication abnormality handling mechanism shall be used to deal with it.

[0072] For the chain communication method in step 2), the specific expression is:

[0073] Establish communication between channel A of each differential protection device and channel B of the upper differential protection device at the opposite end of the same line section;

[0074] Establish communication between channel B of each differential protection device and channel A of the lower differential protection device at the opposite end of the same line section;

[0075] Channel B of the head-end device S1 is connected to channel A of the next-level device S2, channel B of device S2 is connected to channel A of the next-level device S3, and so on; for the protection device at the intermediate node, the device fixedly transmits the electrical quantity of the incoming line CT1 to the upper-level device through channel A, and transmits the electrical quantity of the outgoing line CT2 to the next-level device through channel B. For example, device S2 exchanges L2 information with device S1 through channel A, and exchanges L3 information with device S3 through channel B.

[0076] Regarding step 3) in which the communication status of the power grid line is determined by comparing the identification codes, the specific expression is:

[0077] Protection devices S1~S5 are all equipped with unique local identification codes, and the opposite side identification code of channel A should be set to the local identification code of the opposite side protection device corresponding to protection device channel A, and the opposite side identification code of channel B should be set to the local identification code of the opposite side protection device corresponding to protection device channel B. Take device S2 as an example.

[0078] Protection device S2 receives the local identification code of the opposite protection device S1 through channel A and compares it with the identification code value of the opposite side of channel A of S2. If the two identification codes are consistent, the status of channel A of device S2 is normal. If the two identification codes are inconsistent, the status of channel A of device S2 is abnormal.

[0079] Protection device S2 receives the local identification code of the opposite protection device S3 through channel B and compares it with the identification code value of the opposite side of channel B of S2. If the two identification codes are consistent, the status of channel B of device S2 is normal. If the two identification codes are inconsistent, the status of channel B of device S2 is abnormal.

[0080] For the differential protection devices at both ends of a certain power grid line, if the states of channel B of the upper differential protection device and channel A of the lower differential protection device are both normal, the communication state between the two differential protection devices is normal.

[0081] For the master-slave determination rule described in step 4), Figure 2 As shown, the specific expression is:

[0082] The differential protection device obtains the maximum channel identification code of all upper-level protection devices through channel A, compares its own channel identification code with the maximum channel identification code of all upper-level protection devices, and transmits the larger value to the lower-level differential protection device through channel B;

[0083] Accordingly, the differential protection device obtains the maximum channel identification code of all lower-level protection devices through channel B, compares its own channel identification code with the maximum channel identification code of all lower-level protection devices, and transmits the larger value to the upper-level differential protection device through channel A;

[0084] The maximum channel identification code is determined according to the above method until the differential protection device of the entire line is determined;

[0085] Since the maximum channel identification code corresponds to the maximum value of the local identification codes of each differential protection device, the differential protection device corresponding to the maximum channel identification code is set as the master, which is unique, and the other devices are slaves;

[0086] like Figure 1 As shown, the channel identification code corresponding to device S1 is K1, the channel identification code corresponding to device S2 is K2, the channel identification code corresponding to device S3 is K3, the channel identification code corresponding to device S4 is K4, and the channel identification code corresponding to device S5 is K5. The determination process is as follows:

[0087] Device S2 receives the identification code K1 from device S1 via channel A, compares its own channel identification code K2 with the values of K1, and after identification, transmits the larger of the two, max{K1, K2}, to device S3 via channel B. Simultaneously, it receives the maximum channel identification code max{K3, K4, K5} of all lower-level devices via channel B, compares K2 with the values of max{K3, K4, K5}, and after identification, transmits the larger of the two, max{K2, K3, K4, K5}, to device S1 via channel A.

[0088] Device S3 receives the maximum channel identification code max{K1, K2} of all upper-level devices via channel A, compares its own channel identification code K3 with the values of max{K1, K2}, and after identification, transmits the larger of the two, max{K1, K2, K3}, to device S4 via channel B. Simultaneously, it receives the maximum channel identification code max{K4, K5} of all lower-level devices via channel B, compares the values of K3 with the values of max{K4, K5}, and after identification, transmits the larger of the two, max{K3, K4, K5}, to device S2 via channel A.

[0089] Device S4 receives the maximum channel identification code max{K1, K2, K3} of all upstream devices via channel A, compares its own channel identification code K4 with the values of max{K1, K2, K3}, and after identification, transmits the larger of the two, max{K1, K2, K3, K4}, to device S5 via channel B. Simultaneously, device S5 receives identification code K5 via channel B, compares the values of K4 and K5, and after identification, transmits the larger of the two, max{K4, K5}, to device S3 via channel A.

[0090] The maximum channel identification code is determined according to the above method until all differential protection devices on the line are determined. The protection device corresponding to the maximum value of the channel identification code is set as the master, which is the only one. The remaining devices are slaves.

[0091] If max{K1,K2,…,K5}=K4, then S4 is the master, the only master, and the rest are slaves.

[0092] The data synchronization mechanism described in step 5) is specifically described as follows:

[0093] The slaves adjacent to the master first synchronize with the master, calculate the channel delay with the master, and then synchronize according to the sampling time adjustment method, such as Figure 1 As shown in the figure, assuming that device S4 is the master, the slaves S3 and S5 adjacent to the master first synchronize with the master S4, calculate the channel delay with the master S4 respectively, and then synchronize according to the sampling time adjustment method. That is, with the master S4 as the reference end, the slaves S3 and S5 are respectively the synchronization ends, and the two sides exchange information in a synchronous manner. The sampling interval of the reference end host S4 is fixed, and a frame of information is fixedly sent to the opposite side in each sampling interval. The synchronization ends S3 and S5 adjust the sampling interval at any time until the synchronization condition is met;

[0094] The slaves that are not adjacent to the master are synchronized based on the slaves that are adjacent to the master (pseudo-master). The reference channel is adjusted to the channel connected to the pseudo-master, that is, the delay with the pseudo-master channel is calculated, and then the synchronization is performed according to the sampling time adjustment method, such as Figure 1 As shown in the figure, assuming that device S4 is the master and slave S2 is not adjacent to master S4, synchronization is performed based on slave S3, which is adjacent to the master. In this case, slave S3 becomes a pseudo-master during the synchronization process between devices S2 and S3. That is, pseudo-master S3 is used as the reference end and slave S2 is used as the synchronization end. Information is exchanged between the two sides in a synchronous manner. Reference end S3 sends a fixed frame of information to slave S2 in each sampling interval. Synchronization end S2 adjusts the sampling interval at any time until the synchronization condition is met.

[0095] The synchronization methods of other slaves are implemented in accordance with the synchronization method with the pseudo-master.

[0096] For the communication exception handling mechanism described in step 6), Figure 3 、 Figure 4 As shown, the specific expression is:

[0097] 1) If Figure 3 As shown in the figure, if there is a power grid line and the communication between the differential protection devices at the nodes at both ends of the line is interrupted or abnormal, the power grid line corresponding to the channel at that location is used as the boundary, and the synchronization relationship is re-established in sections according to the healthy channels to achieve data synchronization of the differential protection devices of the sectioned line;

[0098] For each segment, the internal differential protection device still needs to follow the master-slave determination rules to redefine the master-slave relationship, and still needs to re-synchronize data according to the data synchronization mechanism;

[0099] like Figure 3As shown, assuming that all channels are normal, device S4 is the master. At this time, the channel between devices S2 and S3 is interrupted. Then, two healthy channel line networks are reconstructed based on the existing healthy channels, one of which consists of devices S1 and S2, and the other consists of devices S3, S4, and S5. The segmented line composed of devices S1 and S2 re-determines the master and slave according to the master-slave determination rule and synchronizes according to the synchronization mechanism. If K2>K1, device S2 is the master as the reference end, and device S1 is adjusted and synchronized as the synchronization end. The segmented line composed of devices S3, S4, and S5 also re-determines the master and slave according to the master-slave determination rule and synchronizes according to the synchronization mechanism. That is, device S4 is the master as the reference end, and devices S3 and S5 are adjusted and synchronized as the synchronization ends.

[0100] 2) If Figure 4 As shown in the figure, if there is a power grid line, and the optical fiber communication interfaces of the differential protection devices at both ends of the line are not connected in a chain communication manner, and there is an interface connection error, then the differential protection devices at both ends will use the identification code comparison method to determine which channel A or channel B between the two devices is in an abnormal state, and issue a corresponding alarm signal to exit the abnormal section differential protection;

[0101] For lines where both channel A and channel B are in normal status, since the communication status between the differential protection devices at the nodes at both ends is normal, the master-slave relationship needs to be re-determined according to the master-slave determination rule, and data synchronization needs to be re-achieved according to the data synchronization mechanism;

[0102] like Figure 4As shown, channel B of device S1 is mistakenly connected to channel B of device S2, and channel A of device S2 is mistakenly connected to channel A of device S3. At this time, channel A and channel B of device S2 are connected incorrectly. The protection devices are all equipped with three identification code related constants: local identification code, channel A opposite side identification code and channel B opposite side identification code. The status of each channel is determined by comparing the actually transmitted identification code with the identification code constants. The local identification code constant of device S2 is K2, the opposite side identification code constant of channel A is K1, and the opposite side identification code constant of channel B is K3. In the abnormal state, the identification code actually received by channel A of device S2 is the identification code K3 of device S3, which is inconsistent with the constants. The device will report abnormal information such as "Channel A identification code reception error" and "Channel A alarm" and lock the differential protection related to channel A; similarly, the identification code actually received by channel B also does not match the set value, and abnormal information such as "Channel B identification code reception error" and "Channel B alarm" will be reported, and the differential protection related to channel B will be locked; device S1 channel B and device S3 channel A will also report corresponding channel alarms and lock the differential protection of the corresponding channels because they detect that there are no valid frames on the opposite side; under this abnormal condition, the line channel from L5 to substation section B collected by device S3 is still intact, and devices S3, S4, and S5 will re-determine the master and slave according to the master-slave judgment rules, and synchronize according to the synchronization mechanism.

[0103] Accordingly, the present invention also provides a chain-type multi-branch differential protection synchronization system, comprising:

[0104] A setting module is used to pre-install a set of differential protection devices at each node along the entire line backbone network, and each differential protection device is connected in a chain communication manner;

[0105] An acquisition module is used to obtain the power grid line communication status between the differential protection devices at all nodes of the entire backbone network;

[0106] The determination module is used to perform master-slave determination according to a preset master-slave determination rule if the communication status between the differential protection devices in all power grid lines is normal, and perform data synchronization according to a preset data synchronization mechanism based on the determination result; if the communication status between the differential protection devices at the two end nodes of a certain section of line in all power grid lines is abnormal, perform data synchronization according to a preset communication abnormality handling mechanism.

[0107] Furthermore, the nodes include: the transformer substation outlets at both ends of the line and the ring network cabinets or switchgears.

[0108] Furthermore, the differential protection devices are connected in a chain communication manner, including:

[0109] The differential protection device is equipped with dual optical fiber channels for differential protection data exchange, corresponding to channel A and channel B;

[0110] Establish communication between channel A of each differential protection device and channel B of the upper differential protection device at the opposite end of the same line section;

[0111] Establish communication between the channel B of each differential protection device and the channel A of the lower differential protection device at the opposite end of the same line section.

[0112] Furthermore, the acquisition module is used to set a local identification code, a channel A opposite side identification code and a channel B opposite side identification code for each differential protection device, and the local identification code, the channel A opposite side identification code and the channel B opposite side identification code are protection constants, and the communication status of each section of the power grid line is determined by comparing the identification codes.

[0113] Furthermore, the acquisition module is used to

[0114] The opposite side identification code of channel A of each differential protection device is set to the local identification code of the opposite side differential protection device corresponding to channel A of the differential protection device, and the opposite side identification code of channel B of each differential protection device is set to the local identification code of the opposite side differential protection device corresponding to channel B of the differential protection device;

[0115] Each differential protection device receives the identification code of the corresponding opposite protection device through its channel A and compares it with the identification code of the opposite side of channel A. If the two identification codes are consistent, the status of channel A of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel A of the differential protection device is abnormal.

[0116] Each differential protection device receives the identification code of the corresponding opposite protection device through its channel B and compares it with the identification code of the opposite side of channel B. If the two identification codes are consistent, the status of channel B of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel B of the differential protection device is abnormal.

[0117] For the differential protection devices at both ends of a certain line section, if the status of channel B of the upper differential protection device and channel A of the lower differential protection device are both normal, the communication status between the two differential protection devices is normal; otherwise, the communication status of this line section is abnormal.

[0118] The determination module is used to

[0119] The control differential protection device obtains the maximum channel identification code of all upper differential protection devices through channel A, compares the local identification code with the value of the maximum channel identification code of all upper protection devices, and transmits the larger value to the lower differential protection device through channel B; at the same time, the differential protection device obtains the maximum channel identification code of all lower protection devices through channel B, compares the local identification code with the value of the maximum channel identification code of all lower protection devices, and transmits the larger value to the upper differential protection device through channel A; until the comparison of the maximum channel identification codes of the differential protection devices of the entire line is completed, it is determined that the differential protection device corresponding to the one with the largest local identification code of the protection devices of the entire line is the master, the master is unique for the entire line, and the remaining devices are slaves.

[0120] The determination module is used to

[0121] The slaves adjacent to the master are first synchronized with the master, and the channel delay with the master is calculated, and then synchronization is performed according to the sampling time adjustment method; for the slaves not adjacent to the master, the slaves adjacent to the master are set as pseudo-masters, and the channel delay with the pseudo-master is calculated, and then synchronization is performed according to the sampling time adjustment method; and so on, until sampling synchronization is completed along the entire line.

[0122] The determination module is used to

[0123] After determining that the channel A or channel B between the devices at both ends of each section of the line is in an abnormal state, the corresponding device will issue a communication abnormality alarm signal and exit the abnormal section differential protection; for each section without communication abnormality, the internal differential protection device will still redetermine the master-slave relationship based on the master-slave judgment rules, and re-synchronize data based on the data synchronization mechanism.

[0124] The present invention also provides a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to perform any of the methods described above.

[0125] The present invention also provides a computing device, comprising:

[0126] One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing any of the methods described.

[0127] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0128] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0129] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0130] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0131] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A chained multi-branch differential protection synchronization method, characterized in that: include: A set of differential protection devices is pre-installed at each node along the entire line backbone network, and each differential protection device is connected in a chain communication manner; Obtain the power grid line communication status between differential protection devices at all nodes along the entire backbone network; If the communication status between the differential protection devices in all power grid lines is normal, the master-slave judgment is performed according to the preset master-slave judgment rule, and data synchronization is performed according to the preset data synchronization mechanism based on the judgment result; If the communication status between the differential protection devices at the two end nodes of a certain section of the power grid is abnormal, data synchronization is performed according to the pre-set communication abnormality handling mechanism; The differential protection devices are connected in a chain communication manner, including: The differential protection device is equipped with dual optical fiber channels for differential protection data exchange, corresponding to channel A and channel B; Establish communication between channel A of each differential protection device and channel B of the upper differential protection device at the opposite end of the same line section; Establish communication between channel B of each differential protection device and channel A of the lower differential protection device at the opposite end of the same line section; The obtaining of the power grid line communication status between the differential protection devices at all nodes of the entire backbone network includes: Each differential protection device is equipped with a local identification code, a channel A opposite side identification code, and a channel B opposite side identification code. The local identification code, the channel A opposite side identification code, and the channel B opposite side identification code are protection fixed values. The communication status of each section of the power grid is determined by comparing the identification codes. The method of determining the communication status of each section of the power grid by comparing the identification codes includes: The opposite identification code of channel A of each differential protection device is set to the local identification code of the opposite differential protection device corresponding to channel A of the differential protection device; the opposite identification code of channel B of each differential protection device is set to the local identification code of the opposite differential protection device corresponding to channel B of the differential protection device; Each differential protection device receives the identification code of the corresponding opposite protection device through its channel A and compares it with the identification code of the opposite side of channel A. If the two identification codes are consistent, the status of channel A of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel A of the differential protection device is abnormal. Each differential protection device receives the identification code of the corresponding opposite protection device through its channel B and compares it with the identification code of the opposite side of channel B. If the two identification codes are consistent, the status of channel B of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel B of the differential protection device is abnormal. For the differential protection devices at both ends of a certain line section, if the status of channel B of the upper differential protection device and channel A of the lower differential protection device are both normal, the communication status between the two differential protection devices is normal; otherwise, the communication status of this line section is abnormal.

2. The chained multi-branch differential protection synchronization method according to claim 1, characterized in that: The nodes include: the transformer substation outlets at both ends of the line and the ring network cabinets or switchgears.

3. The chained multi-branch differential protection synchronization method according to claim 1, characterized in that: The master-slave determination rule includes: The differential protection device obtains the maximum channel identification code of all upper-level differential protection devices through channel A, compares the local identification code with the maximum channel identification code of all upper-level protection devices, and transmits the larger value to the lower-level differential protection device through channel B. At the same time, the differential protection device obtains the maximum channel identification code of all lower-level protection devices through channel B, compares the local identification code with the maximum channel identification code of all lower-level protection devices, and transmits the larger value to the upper-level differential protection device through channel A. Until the maximum channel identification code of the differential protection device on the entire line is compared, the differential protection device corresponding to the one with the largest local identification code on the entire line is determined to be the master. The master on the entire line is unique, and the remaining devices are slaves.

4. The chained multi-branch differential protection synchronization method according to claim 1, characterized in that: The data synchronization mechanism includes: The slaves adjacent to the master first synchronize with the master, calculate the channel delay with the master, and then synchronize according to the sampling time adjustment method; For slaves that are not adjacent to the master, set the slaves adjacent to the master as pseudo-masters, calculate the channel delay with the pseudo-master, and then synchronize them according to the sampling time adjustment method; and so on, until the sampling synchronization is completed on the entire line.

5. The chained multi-branch differential protection synchronization method according to claim 1, characterized in that: The communication exception handling mechanism includes: After identifying the abnormal channel in channel A or channel B between the devices at both ends of each section of the line, the corresponding device will issue a communication abnormality alarm signal and exit the abnormal section differential protection; For each segment without communication anomalies, the internal differential protection device still redefines the relationship between the master and slave machines based on the master-slave determination rule, and resynchronizes data based on the data synchronization mechanism.

6. A chain-type multi-branch differential protection synchronization system, characterized in that: include: A setting module is used to pre-install a set of differential protection devices at each node along the entire line backbone network, and each differential protection device is connected in a chain communication manner; An acquisition module is used to obtain the power grid line communication status between the differential protection devices at all nodes of the entire backbone network; A determination module is configured to determine whether the differential protection devices in all power grid lines are in normal communication state, perform master-slave determination according to a preset master-slave determination rule, and perform data synchronization according to a preset data synchronization mechanism based on the determination result; If the communication status between the differential protection devices at the two end nodes of a certain section of the power grid is abnormal, data synchronization is performed according to the pre-set communication abnormality handling mechanism; The differential protection devices are connected in a chain communication manner, including: The differential protection device is equipped with dual optical fiber channels for differential protection data exchange, corresponding to channel A and channel B; Establish communication between channel A of each differential protection device and channel B of the upper differential protection device at the opposite end of the same line section; Establish communication between channel B of each differential protection device and channel A of the lower differential protection device at the opposite end of the same line section The acquisition module is used to set a local identification code, a channel A opposite side identification code, and a channel B opposite side identification code for each differential protection device, wherein the local identification code, the channel A opposite side identification code, and the channel B opposite side identification code are protection fixed values, and determine the communication status of each section of the power grid by comparing the identification codes; The acquisition module is used to The opposite side identification code of channel A of each differential protection device is set to the local identification code of the opposite side differential protection device corresponding to channel A of the differential protection device, and the opposite side identification code of channel B of each differential protection device is set to the local identification code of the opposite side differential protection device corresponding to channel B of the differential protection device; Each differential protection device receives the identification code of the corresponding opposite protection device through its channel A and compares it with the identification code of the opposite side of channel A. If the two identification codes are consistent, the status of channel A of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel A of the differential protection device is abnormal. Each differential protection device receives the identification code of the corresponding opposite protection device through its channel B and compares it with the identification code of the opposite side of channel B. If the two identification codes are consistent, the status of channel B of the differential protection device is normal. If the two identification codes are inconsistent, the status of channel B of the differential protection device is abnormal. For the differential protection devices at both ends of a certain line section, if the status of channel B of the upper differential protection device and channel A of the lower differential protection device are both normal, the communication status between the two differential protection devices is normal; otherwise, the communication status of this line section is abnormal.

7. The chained multi-branch differential protection synchronization system according to claim 6, characterized in that: The nodes include: the transformer substation outlets at both ends of the line and the ring network cabinets or switchgears.

8. The chained multi-branch differential protection synchronization system according to claim 6, characterized in that: The determination module is used to The control differential protection device obtains the maximum channel identification code of all upper differential protection devices through channel A, compares the local identification code with the maximum channel identification code of all upper protection devices, and transmits the larger value to the lower differential protection device through channel B. At the same time, the differential protection device obtains the maximum channel identification code of all lower protection devices through channel B, compares the local identification code with the maximum channel identification code of all lower protection devices, and transmits the larger value to the upper differential protection device through channel A. Until the maximum channel identification code of the differential protection device on the entire line is compared, the differential protection device corresponding to the one with the largest local identification code on the entire line is determined to be the master. The master on the entire line is unique, and the remaining devices are slaves.

9. The chained multi-branch differential protection synchronization system according to claim 6, characterized in that: The determination module is used to The slaves adjacent to the master are first synchronized with the master, and the channel delay with the master is calculated, and then synchronization is performed according to the sampling time adjustment method; for the slaves not adjacent to the master, the slaves adjacent to the master are set as pseudo-masters, and the channel delay with the pseudo-master is calculated, and then synchronization is performed according to the sampling time adjustment method; and so on, until sampling synchronization is completed along the entire line.

10. The chained multi-branch differential protection synchronization system according to claim 6, characterized in that: The determination module is used to After determining that the channel A or channel B between the devices at both ends of each section of the line is in an abnormal state, the corresponding device will issue a communication abnormality alarm signal and exit the abnormal section differential protection; for each section without communication abnormality, the internal differential protection device will still redetermine the master-slave relationship based on the master-slave judgment rules, and re-synchronize data based on the data synchronization mechanism.

11. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform the method of any one of claims 1 to 5.

12. A computing device, characterized in that include, One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for executing the method according to any one of claims 1 to 5.

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