A method, device, electronic equipment, and storage medium for multi-terminal differential protection of distribution networks.

Abstract

This invention discloses a method, device, electronic equipment, and storage medium for multi-terminal differential protection in distribution networks, belonging to the field of power automation. The method comprises: acquiring the first electrical quantity information corresponding to the current differential protection device and the equipment input matrix setting value of the current differential ring where the current differential protection device is located; determining the differential protection logic corresponding to the current differential ring based on the equipment input matrix setting value; acquiring the second electrical quantity information of the other differential protection devices that have activated differential protection in the current differential ring, and determining whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If they do not satisfy, the current differential protection device is controlled to operate, and differential protection is performed on the line node where the current differential protection device is located. If they satisfy, differential protection is not required. Therefore, by implementing this invention, the problem of the lack of multi-terminal differential protection methods for multi-terminal wiring lines in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of power automation, and in particular to a method, device, electronic equipment, and storage medium for multi-terminal differential protection of distribution networks. Background Technology

[0002] Traditional medium- and high-voltage transmission lines mostly use point-to-point transmission, with direct connections between two substations or between power plants and substations, employing differential protection based on single-ended electrical quantities. However, with increasing electricity demand, distribution networks have become more complex, with significant differences in wiring methods, distribution branches, and switch types. Furthermore, their operation is highly variable, loads change frequently, and the high proportion of renewable energy integration and the widespread application of new power electronic loads (charging piles) have further complicated the electrical characteristics of distribution networks. This has led to the emergence of multi-ended wiring lines, such as T-connected transmission lines, necessitating multi-ended differential protection methods for these lines. Summary of the Invention

[0003] This invention provides a method, device, electronic equipment, and storage medium for multi-terminal differential protection of distribution networks, which can solve the problem of the lack of multi-terminal differential protection methods for multi-terminal wiring lines in the prior art.

[0004] To address the aforementioned technical problems, embodiments of the present invention provide a method for multi-terminal differential protection of distribution networks, comprising: When the current differential protection device is engaged, the first electrical quantity information corresponding to the current differential protection device and the equipment engagement matrix setting of the current differential ring where the current differential protection device is located are obtained; wherein, the first electrical quantity information includes: voltage data and current data of the line node corresponding to the current differential protection device; a differential ring contains several differential protection devices with different ends; Based on the set value of the equipment input matrix, determine whether each differential protection device included in the current differential ring is engaged in differential protection, and determine the differential protection logic corresponding to the current differential ring based on the differential protection devices that are engaged in differential protection. Obtain the second electrical quantity information of the other differential protection devices that have activated differential protection in the current differential ring, and determine whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If they do not satisfy, control the current differential protection device to operate and perform differential protection on the line node where the current differential protection device is located. If they satisfy, differential protection is not required.

[0005] As a preferred embodiment, each differential protection device is equipped with two single-mode fiber optic interfaces, and each differential protection device communicates with the other differential protection devices through the two single-mode fiber optic interfaces via a fiber optic ring network.

[0006] As a preferred embodiment, the differential protection device sends a data frame containing its own differential data information to other differential protection devices through the single-mode fiber optic interface; The transmission field information in the data frame includes: destination MAC, source MAC, Ethernet frame type, application identifier, data length, transmission delay correction field, counter, sampling delay, current data, quality bit, and switch status information.

[0007] As a preferred embodiment, the step of obtaining the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, and determining whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential loop, includes: Obtain the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, the sampling delay of all differential protection devices, and the transmission delay between all differential protection devices; Based on the sampling delay and transmission delay, the sampling time of each data in the first electrical quantity information and the second electrical quantity information is determined. The data in the first electrical quantity information and the second electrical quantity information are time-synchronized according to the sampling time. It is then determined whether the data in the first electrical quantity information and the second electrical quantity information at the same time satisfy the differential protection logic corresponding to the current differential loop.

[0008] Based on the above embodiments, another embodiment of the present invention provides a multi-terminal differential protection device for distribution networks, including: a data acquisition module, a differential protection logic determination module, and a differential protection module; The data acquisition module is used to acquire the first electrical quantity information corresponding to the current differential protection device and the equipment activation matrix setting of the current differential ring where the current differential protection device is located when the current differential protection device is put into differential protection; wherein, the first electrical quantity information includes: voltage data and current data of the line node corresponding to the current differential protection device; a differential ring contains a number of differential protection devices at different ends; The differential protection logic determination module is used to determine whether each differential protection device included in the current differential ring is engaged in differential protection according to the equipment engagement matrix setting, and to determine the differential protection logic corresponding to the current differential ring according to the differential protection devices engaged in differential protection. The differential protection module is used to obtain the second electrical quantity information of the other differential protection devices that have activated differential protection in the current differential ring, and to determine whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If they do not satisfy, the module controls the current differential protection device to operate and performs differential protection on the line node where the current differential protection device is located. If they satisfy, differential protection is not required.

[0009] As a preferred embodiment, each differential protection device is equipped with two single-mode fiber optic interfaces, and each differential protection device communicates with the other differential protection devices through the two single-mode fiber optic interfaces via a fiber optic ring network.

[0010] As a preferred embodiment, the differential protection device sends a data frame containing its own differential data information to other differential protection devices through the single-mode fiber optic interface; The transmission field information in the data frame includes: destination MAC, source MAC, Ethernet frame type, application identifier, data length, transmission delay correction field, counter, sampling delay, current data, quality bit, and switch status information.

[0011] As a preferred embodiment, the step of obtaining the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, and determining whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential loop, includes: Obtain the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, the sampling delay of all differential protection devices, and the transmission delay between all differential protection devices; Based on the sampling delay and transmission delay, the sampling time of each data in the first electrical quantity information and the second electrical quantity information is determined. The data in the first electrical quantity information and the second electrical quantity information are time-synchronized according to the sampling time. It is then determined whether the data in the first electrical quantity information and the second electrical quantity information at the same time satisfy the differential protection logic corresponding to the current differential loop.

[0012] Based on the above embodiments, another embodiment of the present invention provides an electronic device, the device including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the multi-terminal differential protection method for distribution networks described in the above embodiments of the invention.

[0013] Based on the above embodiments, another embodiment of the present invention provides a storage medium, the storage medium including a stored computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute the distribution network multi-terminal differential protection method described in the above embodiments of the invention.

[0014] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: This invention provides a method for multi-terminal differential protection in a distribution network. When a differential protection device is activated, the method acquires first electrical quantity information corresponding to the current differential protection device and the equipment activation matrix setting of the current differential ring where the current differential protection device is located. The first electrical quantity information includes voltage and current data of the line node corresponding to the current differential protection device. A differential ring contains several differential protection devices at different terminals. Based on the equipment activation matrix setting, the method determines whether each differential protection device in the current differential ring is activated, and determines the differential protection logic corresponding to the current differential ring based on the activated differential protection devices. The method acquires second electrical quantity information of the remaining activated differential protection devices in the current differential ring, and determines whether the first and second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If not, the method controls the current differential protection device to operate, providing differential protection to the line node where the current differential protection device is located; if the conditions are met, differential protection is not required. For multi-terminal distribution network lines, this invention integrates the differential protection devices of multiple terminals into a differential ring and sets the equipment activation matrix values ​​for the differential ring. By setting the equipment activation matrix values, it can be determined whether each differential protection device contained in the differential ring is in differential protection mode, and the differential protection logic corresponding to the current differential ring can be determined. Thus, based on the differential protection logic, it can be determined whether each differential protection device in the differential ring needs to perform differential protection, thereby realizing multi-terminal differential protection for multi-terminal wiring lines. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a method for multi-terminal differential protection of a distribution network according to an embodiment of the present invention; Figure 2 This is the installation and configuration diagram for distribution network differential protection; Figure 3 This is a connection diagram for multi-terminal differential protection in a ring network configuration; Figure 4 This is a schematic diagram of the transmission delay update method for differential protection devices; Figure 5 This is a schematic diagram of the structure of a multi-terminal differential protection device for a distribution network provided in an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0018] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0021] In the description of the embodiments of this application, the terms "multiple" and "several" refer to two or more (including two), similarly, "multiple groups" refer to two or more (including two groups), and "multiple pieces" refer to two or more (including two pieces).

[0022] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0023] Example 1 Please refer to Figure 1 To address the lack of multi-terminal differential protection methods for multi-terminal wiring lines in existing technologies, this invention provides a flowchart of a distribution network multi-terminal differential protection method, illustrating the configuration, protection settings, data frame format, and processing methods of distribution network multi-terminal differential protection, including the following specific steps: S1. When the current differential protection device is engaged in differential protection, the first electrical quantity information corresponding to the current differential protection device and the equipment engagement matrix setting of the current differential ring where the current differential protection device is located are obtained; wherein, the first electrical quantity information includes: voltage data and current data of the line node corresponding to the current differential protection device; a differential ring contains several differential protection devices at different ends; Preferably, each differential protection device is equipped with two single-mode fiber optic interfaces, and each differential protection device communicates with the other differential protection devices through the two single-mode fiber optic interfaces via a fiber optic ring network.

[0024] Preferably, the differential protection device sends a data frame containing its own differential data information to other differential protection devices through the single-mode fiber optic interface; wherein, the transmission field information in the data frame includes: destination MAC, source MAC, Ethernet frame type, application identifier, data length, transmission delay correction field, counter, sampling delay, current data, quality bit, and switch status information.

[0025] In one specific embodiment, please refer to Figure 2 This is an installation and configuration diagram for distribution network differential protection, showing a typical wiring method for distribution network lines, including lines, substation outgoing switches, three branch switches, and two sectionalizing switches. The branch switches can be connected to photovoltaic systems and loads, etc.

[0026] Specifically, for Figure 2 The following describes the specific implementation method of multi-terminal differential protection: 1. Installation and configuration methods for multi-terminal differential protection: (1) Each branch switch is equipped with a PT (voltage transformer) and a CT (current transformer) to collect voltage and current data of the line, respectively, and to "reduce" high voltage and large current to low voltage and small current by a fixed ratio, so as to provide basic electrical quantity information for differential protection. (2) Differential protection devices are installed at each switch, namely Unit1, Unit2, Unit3, Unit4, Unit5, and Unit6; (3) Please refer to Figure 3 This is a connection diagram for multi-terminal differential protection in a ring network configuration. Each differential protection device has a 100 Mbps single-mode fiber optic interface and supports HSR ring network mode. The two optical ports can be identified as port A and port B. All differential protection devices are connected via a fiber optic ring network. Figure 3 As shown, Unit 1's A net is connected to Unit 2's B net, Unit 2's A net is connected to Unit 3's B net, Unit 3's A net is connected to Unit 4's B net, Unit 4's A net is connected to Unit 5's B net, Unit 5's A net is connected to Unit 6's B net, and Unit 6's A net is connected to Unit 1's B net.

[0027] (4) The differential protection operates in a peer-to-peer mode. Each differential protection device (Unit1~Unit6) is at the same operating level and functional status, with no master-slave distinction. Each node (the line node corresponding to the differential protection device) calculates the differential current independently and trips its respective switch after meeting the operating conditions. The specific implementation method is as follows: Unit 1 is installed at the outgoing line switch of the substation. It collects the three-phase voltage of the 10kV busbar and the three-phase current of the outgoing line switch, collects the position of the outgoing line switch, and realizes the tripping and closing of the outgoing line switch. The current calibration is as follows. ; Unit 2 is installed at the first branch switch, collecting the three-phase voltage and three-phase current of the first branch switch, acquiring the position of the first branch switch, and realizing its tripping and closing. The current calibration is as follows. ; Unit 3 is installed at the second branch switch, collecting the three-phase voltage and three-phase current of the second branch switch, acquiring the position of the second branch switch, and realizing its tripping and closing. The current calibration is as follows. ; Unit 4 is installed at the first sectionalizing switch, collecting the three-phase voltage and current of the first sectionalizing switch, acquiring the position of the first sectionalizing switch, and implementing its tripping and closing. The current calibration is as follows. ; Unit 5 is installed at the third branch switch, collecting the three-phase voltage and current of the third branch switch, acquiring the position of the third branch switch, and implementing its tripping and closing. The current calibration is as follows: ; Unit 6 is installed at the second sectionalizing switch, collecting the three-phase voltage and current of the second sectionalizing switch, acquiring the position of the second sectionalizing switch, and realizing its tripping and closing. The current calibration is as follows. ; All differential protection systems share data through a ring network. Each node can obtain the voltage and current of other nodes, and different differential rings can be formed with sectional switches as the boundary. Fault areas are isolated through sectional switches.

[0028] Differential loop 1 includes Unit1, Unit2, Unit3, and Unit4. The differential protection devices of all nodes independently calculate the differential current. Under conditions of no fault within the zone or a fault outside the zone, -( + + ) = 0, when there is a fault in the area, -( + + If the value is greater than 0, after the differential action of each node, its respective switch will be turned off.

[0029] Differential loop 2 includes Unit 4, Unit 5, and Unit 6. The differential protection devices of all nodes independently calculate the differential current. Under conditions of no fault within the zone or a fault outside the zone, -( + ) = 0, when there is a fault in the area, -( + If the value is greater than 0, after the differential action of each node, its respective switch will be turned off.

[0030] When a fault occurs within the loop, the differential current calculation results of all devices within the loop will satisfy "differential current > 0". When the differential current of all devices within the loop is greater than the differential protection setting, all devices will trigger differential action, thereby isolating the fault.

[0031] In conclusion, Figure 3 The six protection devices shown are connected in a physical fiber optic ring network, but are further divided into two differential rings by a sectionalizing switch. Each differential ring is calculated independently, which can achieve regional isolation of faults.

[0032] 2. Data frame format description method for multi-terminal differential protection: Differential protection devices at any node need to provide analog and status information to differential protection devices at other nodes. To increase the number of nodes in the ring network and reduce the data flow, the SV data frame length of the standard IEC61850 needs to be compressed and optimized, transmitting only critical differential data information. The analog information refers to phase A current (Ia), phase B current (Ib), phase C current (Ic), and zero-sequence current (I0). Ia, Ib, and Ic reflect the load current or fault current of the three-phase line, while I0 is used to detect zero-sequence faults (such as single-phase ground faults) and is the core basis for differential protection to determine the fault type and severity. The status information refers to switch status, protection function status, and fault and abnormal status. When calculating the differential current, invalid data can be excluded to avoid malfunctions; rapid tripping is achieved based on interlocking commands, and protection triggering is controlled based on permission signals.

[0033] This invention eliminates the ASN.1 encoding method of SV data frames and directly defines specific transmission field information, including: destination MAC, source MAC, Ethernet frame type, application identifier, data length, counter, sampling delay, transmission delay correction field, and application data composition. The frame format is shown in Table 1 below. Table 1. Data frame format sent by differential protection device The explanation is as follows: (1) The destination MAC address ranges from 01-0C-CD-04-00-01 to 01-0C-CD-04-00-FF. To ensure configuration-free operation of field devices, the destination MAC address is bound to the interval number in the source device information below. When the interval number is 1, the destination MAC address is 01-0C-CD-04-00-01; when the interval number is 2, the destination MAC address is 01-0C-CD-04-00-02; when the interval number is 10, the destination MAC address is 01-0C-CD-04-00-0A; and when the interval number is 255, the destination MAC address is 01-0C-CD-04-00-FF. The data length is 6 bytes. Here, the interval number in the source device information refers to the "interval number" in the differential protection settings, that is, the device number of the differential protection device.

[0034] (2) The source MAC is the physical address of the device's network card, which is determined by the device manufacturer, and the data length is 6 bytes.

[0035] (3) The Ethernet frame type is fixed as 0x88BA and the data length is 2 bytes.

[0036] (4) The application identifier value ranges from 0x4001 to 0x40FF. In order to ensure that the field device is configuration-free, the APPID (application identifier) ​​is bound to the interval number in the source device information below. The device with interval number 1 is 0x4001, the device with number 2 is 0x4002, the device with interval number 10 is 0x400A, and the device with interval number FF is 0x40FF. The data length is 2 bytes.

[0037] (5) The data length is the length of bytes starting from the source device information, with a default of 42 bytes and a data length of 2 bytes.

[0038] (6) Counter, the counter range is 0 to 1000, and the data length is 2 bytes.

[0039] (7) Sampling delay is the time delay from the acquisition of the sample to the output of the message by the differential protection device, in microseconds (µs), and the data length is 4 bytes.

[0040] (8) Transmission Delay Correction Domain (FTCF): In HSR networks, transmission delay includes two parts: the dwell time of a packet within a node and the path delay of the packet between nodes. The dwell time of a packet within a node is the time that the packet stays inside a certain device node. It includes the internal processing time such as the time for the packet to be received in the node's receive buffer, the time for looking up the table, the time for the packet to be moved from the receive buffer to the forwarding buffer, and any possible queuing waiting time. The path delay of a message transmission between nodes is the physical link delay when the message is transmitted between nodes in the HSR network. Its value is calculated by measuring the send / receive delay of request and response messages between nodes. A 10kV distribution line is generally no more than 15 kilometers long. Based on the speed of light (300,000 kilometers per second), the cumulative transmission delay is approximately 50µs. Since 1µs of error corresponds to 0.018 degrees, 50µs corresponds to 0.9 degrees. Because the synchronization requirements for 10kV distribution lines are not high, and to reduce the number of communication messages between nodes, the fiber optic transmission delay in differential protection can be ignored. Therefore, the transmission delay mainly considers the dwell time within the node. The data length is 4 bytes. The delay correction field is a 32-bit unsigned integer, with bit 30 representing the quality bit, bits 0-23 representing the transmission delay, and the other bits reserved. A quality bit value of 1 indicates that the FTCF is invalid, and 0 indicates that the FTCF is valid. The FTCF unit is 8 nanoseconds.

[0041] The length of a 10kV distribution line is generally no more than 15 kilometers. Based on the propagation speed of light at 300,000 kilometers per second, the cumulative transmission delay is about 50µs. Since 1µs of error corresponds to 0.018 degrees, 50µs corresponds to 0.9 degrees. As the synchronization requirements of 10kV distribution network lines are not high, and in order to reduce the communication messages between the two nodes, the fiber optic transmission delay in differential protection can be ignored. Therefore, the transmission delay mainly considers the dwell time within the node.

[0042] (9) The current data are A-phase current, B-phase current and C-phase current respectively. The zero-sequence current is the instantaneous value of the primary side current, the unit is 1mA, and the data length is 4 bytes.

[0043] (11) The voltage data are A-phase voltage, B-phase voltage and C-phase voltage respectively. They are the instantaneous values ​​of the primary side voltage, in units of 10mV, and the data length is 4 bytes.

[0044] (12) Quality bits, 4 bytes in total, voltage and current quality indicators for 7 channels. (13) Status information, a total of 4 bytes. The specific content of the status information is shown in Table 2 below. Other bits can be expanded according to project requirements. Table 2. Specific content of state quantity information 3. Specific processing methods for data frames of multi-terminal differential protection: The sampling rate of differential protection devices from different equipment manufacturers should be uniformly set to 1kHz, with each sampling interruption lasting 1000µs and sending one frame message per sampling interruption. Furthermore, the transmission should be timed using an FPGA (Field Programmable Gate Array), and the delay between the sampling time and the transmission time should remain fixed. The sampling delay should remain constant throughout the transmission process at each node.

[0045] Please refer to Figure 4 This is a schematic diagram of the transmission delay update method for a differential protection device. The transmission delay should be updated in the node forwarding process as follows: like Figure 3 As shown, the transmission delay should increase progressively during node forwarding. When Unit1 sends information to Unit6's network interface A via network interface B, the transmission delay in the message sent by Unit1 is 0. The timestamp of the message received by Unit2 is T21, and the timestamp of the message sent is T23. Therefore, the dwell delay is t1 = T23 - T21. The transmission delay in the message sent by Unit2 is t1, and so on. The delay of the message sent by Unit5 is t1 + t2 + t3 + t4.

[0046] When Unit1 sends information to Unit6's network interface B via network interface A, because it is a direct connection to a node without forwarding, the transmission delay of Unit1 sending the message is 0. The transmission delay handling for other nodes can be deduced similarly.

[0047] Furthermore, the length of a single frame message of the differential protection device is 64 bytes. The device sends messages at a frequency of 1 kHz, and the message traffic generated by each device is 512 kbit / s. When the device uses a commonly used 100 Mbit / s network port, up to 195 differential protection devices can be connected, which can fully meet the needs of field use.

[0048] In addition, the differential protection device should be designed with differential node matrix settings that can be adapted to prevent the differential protection from calculating the current of a branch after the branch has been modified and the branch is no longer in use. The differential protection setting design is shown in Table 3 below: Table 3 Differential Protection Setting Design The description is as follows: (1) The interval number is the interval number within the physical ring, such as Figure 1 Units 1 to 6 within the ring can be numbered 1 to 6 respectively. The interval units mentioned in this document refer to the differential protection devices, and the interval number can be understood as the equipment number of each differential protection device.

[0049] (2) In this interval type, 0 indicates a normal switch, and 1 indicates a segmented switch. Data from ring 1 and ring 2 need to be taken separately for differential operation. For normal switches, ring 1 is used for differential operation. For example... Figure 2 Unit4 is set to 1 for the segmented switch and 0 for the other switches.

[0050] (3) The differential loop 1 and differential loop 2 are set to interval input matrix values, which are applied bit by bit. 1 indicates that the interval is input (bit0: interval 1-bit15: interval 16). Differential loop 1 for Unit 1, Unit 2 and Unit 3 can be set to 0xF, differential loop 1 for Unit 4 can be set to 0xF, differential loop 2 can be set to 0x38, and differential loop 1 for Unit 5 and Unit 6 can be set to 0x38. The interval input matrix value is the same as the equipment input matrix value mentioned in step S1 above. Based on the equipment input matrix value, it can be determined whether the differential protection devices included in the current differential loop are in differential protection mode.

[0051] (4) Differential protection of differential loop 1 is enabled. When the differential protection of this interval is enabled, this setting needs to be enabled. Differential loop 1 and differential loop 2 of Unit 4 need to be enabled, while other devices only need differential protection of differential loop 1 to be enabled.

[0052] The differential protection device should perfectly match the destination MAC address and application identifier. If the match fails, the sampling data is considered interrupted, and differential protection is blocked. If data timeout, parsing error, or sampling counter error occurs during communication, an alarm is triggered instantaneously, and differential protection is blocked. The following explains the binding relationship between the destination MAC address, application identifier, and interval number: For example: the "differential loop 1 interval input matrix setpoint" of the interval unit is set to 0x000F. The destination MAC of Unit2 that Unit1 needs to subscribe to is 01-0C-CD-04-00-02, the destination MAC of Unit3 that it subscribes to is 01-0C-CD-04-00-03, the destination MAC of Unit4 that it subscribes to is 01-0C-CD-04-00-04, the application identifier of Unit2 that Unit1 needs to subscribe to is 0x4002, the application identifier of Unit3 that it subscribes to is 0x4003, and the application identifier of Unit4 that it subscribes to is 0x4004.

[0053] If the destination MAC address is 01-0C-CD-04-00-02 and the application identifier is 0x4002, it will automatically be matched as a unit2 data frame; if the destination MAC address is 01-0C-CD-04-00-03 and the application identifier is 0x4003, it will automatically be matched as a unit3 data frame; if the destination MAC address is 01-0C-CD-04-00-04 and the application identifier is 0x4004, it will automatically be matched as a unit4 data frame.

[0054] For example, differential loop 1 includes Unit1, Unit2, Unit3, and Unit4, and the "interval numbers" of the four corresponding differential protection devices are set sequentially to 1, 2, 3, and 4. If the "differential loop 1 interval activation matrix setting" of each interval unit is set to 0x000F (bit0=1, bit1=1, bit2=1, bit3=1), it means that interval unit 1, interval unit 2, interval unit 3, and interval unit 4 are all activated. At this time, the differential current calculated by each device = -( + + If the branch modification requires removing Unit3, then the "Differential Loop 1 Interval Input Matrix Setting" of Unit1, Unit2, and Unit4 is all set to 0x000B (bit0=1, bit1=1, bit2=0, bit3=1), representing that interval unit 1, interval unit 2, and interval unit 4 are all input. At this time, the differential current calculated by each device is = -( + ).

[0055] In another specific embodiment, for step S1, since the differential protection devices of all line nodes calculate the differential current independently, and when a fault occurs, since the fault occurs within the differential loop, the differential current calculation results of all differential protection devices within the loop will satisfy "differential current > 0". When the differential current of all differential protection devices within the differential loop is greater than the differential protection setting value, all differential protection devices will trigger differential action to isolate the fault. After the differential action of each line node, its respective switch will trip.

[0056] Therefore, in this embodiment, taking a certain current differential protection device as an example, the differential ring in which it is located is the current differential ring. When the current differential protection device is put into differential protection, the voltage data and current data of the line node corresponding to the current differential protection device, as well as the equipment input matrix setting of the current differential ring, are obtained. Further differential protection judgment is made based on the voltage data, current data and equipment input matrix setting.

[0057] S2. Based on the equipment input matrix setting, determine whether each differential protection device included in the current differential ring is in differential protection mode, and determine the differential protection logic corresponding to the current differential ring based on the differential protection devices in differential protection mode. In a specific embodiment, for step S2, after obtaining the current differential ring equipment activation matrix setting value (i.e., the interval activation matrix setting value shown in Table 3) in the above steps, this step can determine whether each differential protection device included in the current differential ring is activated for differential protection based on the equipment activation matrix setting value, and determine the differential protection logic corresponding to the current differential ring. In a differential ring, the corresponding differential protection logic is: the sum of the currents of the differential protection devices in each branch is equal to the current of the differential protection device in the corresponding main circuit.

[0058] For example, if the current differential loop device activation matrix setting is 0x000B (bit0=1, bit1=1, bit2=0, bit3=1), it means that Unit1, Unit2, and Unit4 in the current differential loop are all activated for differential protection, while Unit3 is not activated. In this case, the differential protection logic corresponding to the current differential loop is: the differential current calculated for each device = -( + ).

[0059] S3. Obtain the second electrical quantity information of the other differential protection devices that have activated differential protection in the current differential ring, and determine whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If not, control the current differential protection device to operate and perform differential protection on the line node where the current differential protection device is located. If it satisfies the condition, differential protection is not required.

[0060] Preferably, the step of obtaining the second electrical quantity information of the remaining differential protection devices that have activated differential protection within the current differential loop, and determining whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential loop, includes: obtaining the second electrical quantity information of the remaining differential protection devices that have activated differential protection within the current differential loop, the sampling delay of all differential protection devices, and the transmission delay between all differential protection devices; determining the sampling time of each data in the first electrical quantity information and the second electrical quantity information based on the sampling delay and the transmission delay; performing time synchronization processing on the data in the first electrical quantity information and the second electrical quantity information based on the sampling time; and determining whether the data in the first electrical quantity information and the second electrical quantity information at the same time satisfy the differential protection logic corresponding to the current differential loop.

[0061] In a specific embodiment, for step S3, the differential protection devices maintain constant communication, with each device sending its own electrical quantity information to the others. Therefore, after determining which differential protection devices in the current differential loop are engaged, upon receiving messages from the remaining engaged differential protection devices in the current differential loop, the current device can estimate the corresponding values ​​at a unified time point using the Lagrange interpolation algorithm, based on the sampling delay and transmission delay, and utilizing the known actual sampling time of the discrete sampling data. After data synchronization, the DFT (Discrete Fourier Transform) algorithm can be used to calculate the differential equation, determining whether the first and second electrical quantity information satisfy the differential protection logic corresponding to the current differential loop, thus achieving differential protection.

[0062] Therefore, this invention provides a method for multi-terminal differential protection of distribution networks. This invention targets multi-terminal distribution lines and integrates multi-terminal differential protection devices into a single differential ring. A device activation matrix setting is configured for the differential ring. The device activation matrix setting determines whether each differential protection device within the differential ring is in differential protection mode and identifies the corresponding differential protection logic. Based on this differential protection logic, it can be determined whether each differential protection device within the differential ring needs differential protection, thus achieving multi-terminal differential protection for multi-terminal wiring lines.

[0063] Furthermore, this invention proposes for the first time an interoperable data frame protocol for differential protection devices. On one hand, it discloses previously undisclosed communication protocols from various manufacturers, unifying the external interfaces and data transmission protocols of differential protection devices, thereby achieving interconnection and interoperability among differential protection devices from different manufacturers. On the other hand, compared to the standard IEC61850 data frame, the frame format is more streamlined, adopting a representation method more suitable for transmitting critical data in differential protection devices, effectively reducing data traffic and device message processing pressure. This allows for the connection of over 190 differential protection devices under 100 Mbps bandwidth, fully meeting the configuration requirements of differential protection devices in complex distribution network lines. The unified differential protection device communication protocol forms the basis for subsequent data synchronization and algorithm research, solving the problem of a single source for distribution network differential protection devices, enabling plug-and-play functionality for differential protection devices from different brands, and facilitating the promotion and application of distribution network differential protection devices.

[0064] Example 2 Please refer to Figure 5 This is a schematic diagram of the structure of a distribution network multi-terminal differential protection device according to an embodiment of the present invention. The device includes: a data acquisition module, a differential protection logic determination module, and a differential protection module. The data acquisition module is used to acquire the first electrical quantity information corresponding to the current differential protection device and the equipment activation matrix setting of the current differential ring where the current differential protection device is located when the current differential protection device is put into differential protection; wherein, the first electrical quantity information includes: voltage data and current data of the line node corresponding to the current differential protection device; a differential ring contains a number of differential protection devices at different ends; The differential protection logic determination module is used to determine whether each differential protection device included in the current differential ring is engaged in differential protection according to the equipment engagement matrix setting, and to determine the differential protection logic corresponding to the current differential ring according to the differential protection devices engaged in differential protection. The differential protection module is used to obtain the second electrical quantity information of the other differential protection devices that have activated differential protection in the current differential ring, and to determine whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If they do not satisfy, the module controls the current differential protection device to operate and performs differential protection on the line node where the current differential protection device is located. If they satisfy, differential protection is not required.

[0065] Preferably, each differential protection device is equipped with two single-mode fiber optic interfaces, and each differential protection device communicates with the other differential protection devices through the two single-mode fiber optic interfaces via a fiber optic ring network.

[0066] Preferably, the differential protection device sends a data frame containing its own differential data information to other differential protection devices through the single-mode fiber optic interface; The transmission field information in the data frame includes: destination MAC, source MAC, Ethernet frame type, application identifier, data length, transmission delay correction field, counter, sampling delay, current data, quality bit, and switch status information.

[0067] Preferably, the step of obtaining the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, and determining whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential loop, includes: Obtain the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, the sampling delay of all differential protection devices, and the transmission delay between all differential protection devices; Based on the sampling delay and transmission delay, the sampling time of each data in the first electrical quantity information and the second electrical quantity information is determined. The data in the first electrical quantity information and the second electrical quantity information are time-synchronized according to the sampling time. It is then determined whether the data in the first electrical quantity information and the second electrical quantity information at the same time satisfy the differential protection logic corresponding to the current differential loop.

[0068] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0069] Those skilled in the art will clearly understand that, for convenience and brevity, the specific working process of the device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0070] Example 3 Accordingly, embodiments of the present invention provide an electronic device, the device including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the multi-terminal differential protection method for distribution networks described in the above embodiments of the invention.

[0071] The electronic device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The device may include, but is not limited to, a processor and a memory.

[0072] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the device, connecting various parts of the device via various interfaces and lines.

[0073] Example 4 Accordingly, embodiments of the present invention provide a storage medium, the storage medium including a stored computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute the multi-terminal differential protection method for distribution networks described in the above embodiments of the invention.

[0074] The memory can be used to store the computer program. The processor implements various functions of the device by running or executing the computer program stored in the memory and calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, applications required for at least one function, etc.; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0075] The storage medium is a computer-readable storage medium, and the computer program is stored in the computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0076] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for multi-terminal differential protection of a distribution network, characterized in that, include: When the current differential protection device is engaged, the first electrical quantity information corresponding to the current differential protection device and the equipment engagement matrix setting of the current differential ring where the current differential protection device is located are obtained; wherein, the first electrical quantity information includes: voltage data and current data of the line node corresponding to the current differential protection device; a differential ring contains several differential protection devices with different ends; Based on the set value of the equipment input matrix, determine whether each differential protection device included in the current differential ring is engaged in differential protection, and determine the differential protection logic corresponding to the current differential ring based on the differential protection devices that are engaged in differential protection. Obtain the second electrical quantity information of the other differential protection devices that have activated differential protection in the current differential ring, and determine whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If they do not satisfy, control the current differential protection device to operate and perform differential protection on the line node where the current differential protection device is located. If they satisfy, differential protection is not required.

2. The distribution network multi-terminal differential protection method as described in claim 1, characterized in that, Each differential protection device is equipped with two single-mode fiber optic interfaces, and each differential protection device communicates with the other differential protection devices through the two single-mode fiber optic interfaces via a fiber optic ring network.

3. The distribution network multi-terminal differential protection method as described in claim 2, characterized in that, The differential protection device sends a data frame containing its own differential data information to other differential protection devices through the single-mode fiber optic interface; The transmission field information in the data frame includes: destination MAC, source MAC, Ethernet frame type, application identifier, data length, transmission delay correction field, counter, sampling delay, current data, quality bit, and switch status information.

4. The distribution network multi-terminal differential protection method as described in claim 3, characterized in that, The step of obtaining the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, and determining whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential loop, includes: Obtain the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, the sampling delay of all differential protection devices, and the transmission delay between all differential protection devices; Based on the sampling delay and transmission delay, the sampling time of each data in the first electrical quantity information and the second electrical quantity information is determined. The data in the first electrical quantity information and the second electrical quantity information are time-synchronized according to the sampling time. It is then determined whether the data in the first electrical quantity information and the second electrical quantity information at the same time satisfy the differential protection logic corresponding to the current differential loop.

5. A multi-terminal differential protection device for distribution networks, characterized in that, include: Data acquisition module, differential protection logic determination module, and differential protection module; The data acquisition module is used to acquire the first electrical quantity information corresponding to the current differential protection device and the equipment activation matrix setting of the current differential ring where the current differential protection device is located when the current differential protection device is put into differential protection; wherein, the first electrical quantity information includes: voltage data and current data of the line node corresponding to the current differential protection device; a differential ring contains a number of differential protection devices at different ends; The differential protection logic determination module is used to determine whether each differential protection device included in the current differential ring is engaged in differential protection according to the equipment engagement matrix setting, and to determine the differential protection logic corresponding to the current differential ring according to the differential protection devices engaged in differential protection. The differential protection module is used to obtain the second electrical quantity information of the other differential protection devices that have activated differential protection in the current differential ring, and to determine whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential ring. If they do not satisfy, the module controls the current differential protection device to operate and performs differential protection on the line node where the current differential protection device is located. If they satisfy, differential protection is not required.

6. The distribution network multi-terminal differential protection device as described in claim 5, characterized in that, Each differential protection device is equipped with two single-mode fiber optic interfaces, and each differential protection device communicates with the other differential protection devices through the two single-mode fiber optic interfaces via a fiber optic ring network.

7. The distribution network multi-terminal differential protection device as described in claim 6, characterized in that, The differential protection device sends a data frame containing its own differential data information to other differential protection devices through the single-mode fiber optic interface; The transmission field information in the data frame includes: destination MAC, source MAC, Ethernet frame type, application identifier, data length, transmission delay correction field, counter, sampling delay, current data, quality bit, and switch status information.

8. The distribution network multi-terminal differential protection device as described in claim 7, characterized in that, The step of obtaining the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, and determining whether the first electrical quantity information and the second electrical quantity information satisfy the differential protection logic corresponding to the current differential loop, includes: Obtain the second electrical quantity information of the remaining differential protection devices that are engaged in differential protection within the current differential loop, the sampling delay of all differential protection devices, and the transmission delay between all differential protection devices; Based on the sampling delay and transmission delay, the sampling time of each data in the first electrical quantity information and the second electrical quantity information is determined. The data in the first electrical quantity information and the second electrical quantity information are time-synchronized according to the sampling time. It is then determined whether the data in the first electrical quantity information and the second electrical quantity information at the same time satisfy the differential protection logic corresponding to the current differential loop.

9. An electronic device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the distribution network multi-terminal differential protection method as described in any one of claims 1 to 4.

10. A storage medium, characterized in that, The storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device where the storage medium is located to perform the distribution network multi-terminal differential protection method as described in any one of claims 1 to 4.

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