A method, system and storage medium for distributed protection of power distribution network feeders

Abstract

This invention discloses a distributed protection method for distribution network feeders and a system incorporating this method. The distributed protection method utilizes FTUs (Feeder Terminal Units), with ring main units and incoming switches as processing units. It establishes a numbering rule for the FTU control switches, establishes communication between associated FTUs, and performs logical judgments based on the collected voltage, current, and frequency values ​​of switches and buses within the ring main unit, according to pre-defined fault identification, fault isolation, and network reconfiguration logics. This facilitates the exchange of inter-FTU blocking information, anomaly information, and reconfiguration information, thereby achieving fault isolation and network reconfiguration.

Description

Technical Field

[0001] This invention relates to the field of power distribution technology, and in particular to a method, system and storage medium for distributed protection of power distribution network feeders. Background Technology

[0002] During operation, power distribution networks inevitably experience faults due to equipment aging, natural disasters, and other factors. The radial structure of a power distribution network makes it susceptible to power outages during fault conditions, reducing power supply reliability and impacting user experience. In this context, fault self-healing in power distribution networks can improve fault handling efficiency, shorten power outage time for users, minimize the impact of faults and load interruption time, and thus better guarantee users' power experience.

[0003] Distribution automation is the foundation for self-healing faults in distribution networks, and feeder automation (FA) is its key core. The function of FA is to quickly locate faults, rapidly isolate faulty sections, and quickly restore power to non-faulty sections. FA fault handling modes can be divided into centralized FA, local FA, and intelligent distributed FA. With the continuous development of distribution networks, network structures are becoming increasingly complex, load types are increasing, and system operation modes are becoming more varied. This leads to a continuous increase in fault handling time for centralized and local FA, and their fault location and fault tolerance capabilities cannot meet the development needs of distribution networks.

[0004] With the development of new energy technologies and smart grids, distributed generation (DG) will be widely integrated and applied, and the distribution network is transforming from passive to active. These generators are mostly installed near or near consumer units, thus dispersed throughout the distribution network. Furthermore, the dispatch of these energy sources is uncontrolled, as is the control of active and reactive power. Since solar photovoltaic (PV) and wind power are intermittent or dependent on rainfall, their power generation is uncertain, and predicting and estimating the behavior and impact of power electronic generators during faults is complex. These devices have low or zero mechanical inertia, depending on the technology used, and lack inductive characteristics, failing to generate fault currents based on electromagnetic and rotational characteristics. Besides a very rapid envelope decay of the fault current, their behavior in these events depends primarily on the manufacturer's internal control strategies, rather than their physical parameters and the type and location of the fault. Moreover, the output current is finite due to the low thermal limits of the semiconductors used in their structure to avoid overheating and damage to their operation. Studies show that the fault current of these generators can range from 1.06 pu to 7.0 pu, depending on power, type, and embedded technology. Therefore, due to the limitation of fault current, traditional distributed protection methods are no longer applicable to distribution feeders that are mainly composed of photovoltaic distributed generators (PVDG).

[0005] Most existing FA logic uses switches as logical nodes and makes judgments based on the logical relationships between switches. However, considering that the feeder terminal units (FTUs) that generally execute FA are deployed with ring main units and incoming switches as objects, differential protection is more effective for faults within these objects. However, there is currently a lack of protection methods that use ring main units or incoming switches as logical processing objects. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a distributed protection method for distribution network feeders. The method uses FTUs (Feeder Terminal Units) and ring main units (RMUs) and incoming switches as processing units. It establishes a numbering rule for the FTU control switches, establishes associated FTU communication, and performs logical judgments based on the collected voltage, current, and frequency values ​​of the switches and buses within the RMU according to pre-defined fault identification, fault isolation, and network reconstruction logic. This completes the exchange of inter-FTU blocking information, abnormal information, and reconstruction information, achieving fault isolation and network reconstruction. The fault equipment and information transmission logic includes seven logics: non-power supply side fault blocking, non-power supply side fault abnormality handling, load side fault abnormality handling, power supply side grid fault abnormality handling, load side power supply fault abnormality handling, RMU internal fault handling, and simultaneous internal and external fault handling.

[0007] The present invention also proposes a system and storage medium having the above-mentioned distributed protection method for power distribution network feeders.

[0008] The method for distributed protection of distribution network feeders according to a first aspect of the present invention is characterized by comprising the following steps:

[0009] Using feeder terminal units, with ring main units and incoming switches as processing units, we formulate numbering rules for the control switches of feeder terminal units and establish communication between related feeder terminal units.

[0010] Based on the collected voltage, current, and frequency values ​​of the switches and busbars inside the ring main unit;

[0011] Based on the voltage, current, and frequency values ​​of the switch and bus, logical judgments are made according to preset fault identification logic, fault isolation logic, and network reconstruction logic to complete the interaction of inter-feed terminal unit blocking information, abnormal information, and reconstruction information.

[0012] According to some embodiments of the present invention, the numbering rule for the control switches of the feeder terminal unit can be divided into three parts, including:

[0013] The switches in the ring main unit are numbered by themselves, and the numbering consists of three digits. The switch numbers in the ring main unit cannot be repeated.

[0014] The associated feeder terminal unit number is the feeder terminal unit number to which the external switch of the ring main unit adjacent to the control switch of the feeder terminal unit belongs. The feeder terminal unit number is a three-digit number, which is uniformly set according to a power distribution feeder, and the number cannot be repeated within a feeder. If the control switch of the feeder terminal unit has no adjacent external switch of the ring main unit and its corresponding feeder terminal unit, the number is 000.

[0015] The associated feeder terminal unit switch status is 0, which indicates that it is open and 1 indicates that it is closed. The associated feeder terminal unit switch refers to the external switch of the ring network cabinet adjacent to the feeder terminal unit control switch. If the feeder terminal unit control switch has no adjacent external switch of the ring network cabinet and its corresponding feeder terminal unit, then the number is 0.

[0016] According to some embodiments of the present invention, the step of performing logical judgments according to the set fault identification logic, fault isolation logic, and network reconstruction logic to complete the interaction of inter-feeder terminal unit interlocking information, abnormal information, and reconstruction information includes:

[0017] Fault identification detects abnormal operating status of the busbar. Based on the current direction of all switches and the associated feeder terminal unit number, it performs fault handling and information transmission according to seven logics: non-power supply side fault blocking, non-power supply side fault abnormal handling, load side fault abnormal handling, power supply side grid fault abnormal handling, load side power supply fault abnormal handling, ring network cabinet internal fault handling, and simultaneous internal and external fault handling. Finally, it executes switch change refresh logic. If a switch is activated, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0018] Fault isolation is performed by processing the blocking and abnormal information sent by adjacent feeder terminal units. Based on the adjacent feeder terminal unit number, the corresponding associated switch is located. Based on the current direction of the associated switch, the blocking signal processing logic, abnormal signal processing logic, and trip relay execution processing logic are followed to perform fault isolation operation. Finally, the switch change refresh logic is executed. If a switch is activated, a switch change signal is sent to the associated feeder terminal unit. According to the numbering rules, the third part of the corresponding switch number is refreshed.

[0019] Network reconfiguration detects bus voltage loss. Based on the reconfiguration logic within the ring main unit, the external reconfiguration signal sending logic, and the reconfiguration signal processing logic, power is restored to the under-voltage ring main unit. Finally, the switch change refresh logic is executed. If a switch action occurs, a switch change signal is sent to the associated feeder terminal unit. According to the numbering rules, the third part of the corresponding switch number is refreshed.

[0020] Furthermore, in the fault identification step, the non-power supply side fault blocking, non-power supply side fault anomaly handling, load side fault anomaly handling, power supply side grid fault anomaly handling, load side power supply fault anomaly handling, ring mains cabinet internal fault handling, and simultaneous internal and external fault handling within the ring mains cabinet include:

[0021] Non-power supply side fault blocking includes: if any one of the following operating conditions is detected: low voltage, overvoltage, low frequency, or overfrequency on the bus or any switch overcurrent is detected, if the switch current flows to the bus or there is no current, then blocking information is sent to the associated feeder terminal unit; if there is no associated feeder terminal unit, then no blocking information is sent.

[0022] Non-power supply side grid fault abnormality handling includes: detecting any one of the following operating conditions: low voltage, overvoltage, low frequency, or overfrequency on the bus or any switch overcurrent. If the switch current flows out of the bus and the switch has an associated feeder terminal unit, the abnormal information of the switch is sent to its associated feeder terminal unit and the trip relay is triggered.

[0023] Load-side fault handling includes: if any one of the following conditions is detected: low voltage, overvoltage, low frequency, or overfrequency on the bus or any switch overcurrent is detected, if the switch current flows out of the bus, and if there is no associated feeder terminal unit or the associated feeder terminal unit is in the open state, then the switch will be tripped and locked.

[0024] Load-side power supply fault handling includes: detecting any one of the following operating conditions on the bus: low voltage, overvoltage, low frequency, or overfrequency, or any switch overcurrent. If all switches have no current and the waveform shows that the current flowed to the bus before the fault and there is no associated feeder terminal unit, the switch is tripped and locked.

[0025] Fault handling within the ring main unit includes: if the differential current of each switch bus tie exceeds the limit, all switches in the ring main unit will trip and be locked. If the switch current flows to the bus or there is no current, a lockout message will be sent to the associated feeder terminal unit. If there is no associated feeder terminal unit, no lockout message will be sent.

[0026] The handling of simultaneous faults in the ring main unit and external circuits includes: if the differential current of each switch bus tie exceeds the limit, all switches in the ring main unit will trip and be locked. If the switch current flows out of the bus and the switch has an associated feeder terminal unit, the abnormal information of the switch will be sent to its associated feeder terminal unit.

[0027] Furthermore, in the fault isolation step, the blocking signal processing logic, the abnormal signal processing logic, and the trip relay execution processing logic include:

[0028] The blocking signal processing logic clears the trip relay if a blocking signal is received.

[0029] The abnormal signal processing logic is as follows: if an abnormal signal is received, the corresponding associated switch is found according to the feeder terminal unit number from which the abnormal signal originates. If the switch current flows out of the bus or there is no current, the switch trips and is locked.

[0030] The trip relay executes the processing logic, and after the trip relay time expires, it trips the corresponding switch.

[0031] Furthermore, in the network reconfiguration step, the reconfiguration logic within the ring network cabinet, the external reconfiguration signal transmission logic, and the reconfiguration signal processing logic include:

[0032] The reconfiguration logic within the ring main unit indicates that the feeder terminal unit detects a bus voltage loss and that there is an open or unblocked switch. A time relay is activated, and after the time relay expires, the switch is closed. If multiple such switches exist, the switch with voltage on its other side is selected for execution; if all switches have voltage or none have voltage, one of them is selected.

[0033] The external reconfiguration signal sending logic is as follows: When the feeder terminal unit detects a bus voltage loss, there is a switch associated with the feeder terminal unit, but the switch status of the associated switch is open. A reconfiguration signal is sent to the feeder terminal unit associated with the switch. If there are multiple switches with associated feeder terminal units, any one of them is selected.

[0034] The reconfiguration signal processing logic is as follows: When the feeder terminal unit receives the reconfiguration signal, it determines whether there is voltage on the bus. If there is voltage, it determines whether the associated switch is closed based on the feeder terminal unit number of the source signal. If the switch is open and not locked, the time relay is activated. After the time relay expires, the switch is closed.

[0035] According to a second aspect of the present invention, a distributed protection system for distribution network feeders is characterized in that it comprises:

[0036] The rule-making module can use feeder terminal units, with ring main units and incoming switches as processing units, to formulate numbering rules for the control switches of feeder terminal units and establish communication between associated feeder terminal units.

[0037] The information acquisition module collects voltage, current, and frequency values ​​from the switches and busbars within the ring main unit.

[0038] The logic judgment module can perform logical judgments based on the voltage, current, and frequency values ​​of the switch and bus, according to preset fault identification logic, fault isolation logic, and network reconstruction logic, and complete the interaction of inter-feed terminal unit blocking information, abnormal information, and reconstruction information.

[0039] According to some embodiments of the present invention, the rule-making module divides the rule-making process into the following three rules:

[0040] The switches in the ring main unit are numbered by themselves, and the numbering consists of three digits. The switch numbers in the ring main unit cannot be repeated.

[0041] The associated feeder terminal unit number is the feeder terminal unit number to which the external switch of the ring main unit adjacent to the control switch of the feeder terminal unit belongs. The feeder terminal unit number is a three-digit number, which is uniformly set according to a power distribution feeder, and the number cannot be repeated within a feeder. If the control switch of the feeder terminal unit has no adjacent external switch of the ring main unit and its corresponding feeder terminal unit, the number is 000.

[0042] The associated feeder terminal unit switch status is 0, indicating open and 1, indicating closed. The associated feeder terminal unit switch refers to the external switch of the ring main unit adjacent to the feeder terminal unit control switch. If the feeder terminal unit control switch has no adjacent external switch of the ring main unit and its corresponding feeder terminal unit, then this number is 0.

[0043] According to some embodiments of the present invention, the logic judgment module includes:

[0044] The fault identification unit can detect abnormal operating status of the bus. Based on the current direction of all switches and the associated feeder terminal unit number, it performs fault processing and information transmission according to seven logics: non-power supply side fault blocking, non-power supply side fault abnormal handling, load side fault abnormal handling, power supply side grid fault abnormal handling, load side power supply fault abnormal handling, ring network cabinet internal fault handling, and simultaneous internal and external fault handling. Finally, it executes the switch change refresh logic. If a switch is activated, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0045] The fault isolation unit processes the blocking and abnormal information sent by the adjacent feeder terminal units. Based on the adjacent feeder terminal unit number, it finds the corresponding associated switch. Based on the current direction of the associated switch, it performs fault isolation operation according to the blocking signal processing logic, abnormal signal processing logic, and trip relay execution logic. Finally, it executes the switch change refresh logic. If there is a switch action, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0046] The network reconfiguration unit detects bus voltage loss and restores power to the under-voltage ring main unit according to the reconfiguration logic within the ring main unit, the external reconfiguration signal sending logic, and the reconfiguration signal processing logic. Finally, it executes the switch change refresh logic. If there is a switch action, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0047] According to a third aspect of this application, a computer-readable storage medium is provided that stores computer-executable instructions for performing the above-described distributed protection method for power distribution network feeders.

[0048] This method, along with its corresponding system and storage medium, utilizes FTUs (Feeder Terminal Units) and ring main units (RMUs) and incoming switches as processing units. It establishes a numbering rule for FTU control switches, builds communication between associated FTUs, and performs logical judgments based on the collected voltage, current, and frequency values ​​of switches and buses within the RMU, according to pre-defined fault identification, fault isolation, and network reconstruction logic. This facilitates the exchange of inter-FTU blocking, anomaly, and reconstruction information, achieving fault isolation and network reconstruction. The fault equipment and information transmission logic includes seven logics: non-power supply side fault blocking, non-power supply side fault anomaly handling, load side fault anomaly handling, power supply side grid fault anomaly handling, load side power supply fault anomaly handling, RMU internal fault handling, and simultaneous internal and external fault handling. This method not only enables distributed protection and network optimization after distribution network faults by focusing solely on RMUs and incoming switches and relying on communication between adjacent FTUs, but also facilitates fault handling after renewable energy integration.

[0049] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0051] Figure 1 This is a schematic diagram of the steps of the distributed protection method for distribution network feeders according to an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram illustrating the numbering rules for the FTU control switch according to an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of the FTU and switch configuration according to an embodiment of the present invention;

[0054] Figure 4 for Figure 1 A detailed step diagram of step S300 is shown in the figure;

[0055] Figure 5 This is a schematic diagram of the power grid side fault handling logic according to an embodiment of the present invention;

[0056] Figure 6 This is a schematic diagram of the load-side fault handling logic according to an embodiment of the present invention;

[0057] Figure 7 This is a schematic diagram of the fault handling logic within the ring main unit according to an embodiment of the present invention;

[0058] Figure 8 This is a schematic diagram of the fault isolation processing logic in an embodiment of the present invention;

[0059] Figure 9 This is a schematic diagram of the network reconstruction processing logic in an embodiment of the present invention;

[0060] Figure 10 This is a typical feeder example 1 of the present invention;

[0061] Figure 11 This is a typical feeder example 2 of the present invention;

[0062] Figure 12 This is the result of processing a typical feeder fault scenario 1 according to an embodiment of the present invention;

[0063] Figure 13 This is the result of processing a typical feeder fault scenario 2 according to an embodiment of the present invention;

[0064] Figure 14 This is the result of processing a typical feeder fault scenario 3 according to an embodiment of the present invention;

[0065] Figure 15 This is the result of processing a typical feeder fault scenario 4 according to an embodiment of the present invention;

[0066] Figure 16 This is the result of processing a typical feeder fault scenario 5 according to an embodiment of the present invention;

[0067] Figure 17 This is a structural block diagram of a distributed protection system for power distribution network feeders according to an embodiment of the present invention. Detailed Implementation

[0068] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0069] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0070] To address the shortcomings of existing technical solutions, this application provides a distributed protection method for distribution network feeders. This method uses FTUs (Feeder Terminal Units) and ring main units and incoming switches as processing units. It establishes a numbering rule for FTU control switches, establishes associated FTU communication, and performs logical judgments based on the collected voltage, current, and frequency values ​​of switches and buses within the ring main unit, according to the set fault identification logic, fault isolation logic, and network reconstruction logic. This completes the interaction of inter-FTU blocking information, abnormal information, and reconstruction information, realizing fault isolation and network reconstruction. The fault equipment and information transmission logic includes seven logics: non-power supply side fault blocking, non-power supply side fault abnormal handling, load side fault abnormal handling, power supply side grid fault abnormal handling, load side power supply fault abnormal handling, ring main unit internal fault handling, and simultaneous internal and external fault handling within the ring main unit.

[0071] Reference Figure 1 The method includes at least the following steps:

[0072] Step S100: Using the feeder terminal unit, with the ring main unit and incoming switch as processing units, formulate the numbering rules for the control switches of the feeder terminal unit and establish communication between the associated feeder terminal units.

[0073] Step S200: Collect the voltage, current, and frequency values ​​of the switches and busbars inside the ring main unit.

[0074] Step S300: Based on the voltage, current, and frequency values ​​of the switch and bus, perform logical judgments according to the preset fault identification logic, fault isolation logic, and network reconstruction logic to complete the interaction of inter-feed terminal unit blocking information, abnormal information, and reconstruction information.

[0075] Furthermore, referring to Figure 2 The numbering rules in step S100 above can be divided into the following three parts:

[0076] (1) The first part is the switch number of the ring main unit, which consists of three digits. The switch numbers in the ring main unit cannot be repeated.

[0077] (2) The second part is the associated FTU number. The FTU number to which the external switch of the ring main unit adjacent to the FTU control switch belongs is the associated FTU number. The FTU number is a three-digit number, uniformly set according to a distribution feeder, and the number cannot be repeated within a feeder. If the FTU control switch has no adjacent external switch of the ring main unit and its associated FTU, the number is 000.

[0078] (3) The third part is the associated FTU switch status, where 0 indicates open and 1 indicates closed. The associated FTU switch refers to the external switch of the ring main unit adjacent to the FTU control switch. If the FTU control switch has no adjacent external switch of the ring main unit and its corresponding FTU, then this number is 0.

[0079] Reference Figure 3 The ring main unit is equipped with FTU02, adjacent to FTU01 and FTU03. FTU02 manages the following units within the ring main unit: A11-001-1 (001 is the FTU01 number, 1 indicates the adjacent switch is closed), A12-003-1 (003 is the FTU03 number, 1 indicates the adjacent switch is closed), A01-000-0 (000-0 indicates no adjacent switch or FTU), A02-000-0 (000-0 indicates no adjacent switch or FTU), A03-000-0 (000-0 indicates no adjacent switch or FTU), and A04-000-0 (000-0 indicates no adjacent switch or FTU). FTU02 can detect the voltage, current, and frequency values ​​of the switches and busbars within the ring main unit.

[0080] Furthermore, referring to Figure 4 Step S300 involves performing logical judgments based on the voltage, current, and frequency values ​​of the switch and bus, according to preset fault identification logic, fault isolation logic, and network reconfiguration logic, to complete the interaction of inter-feeder terminal unit blocking information, abnormal information, and reconfiguration information. Specifically, this may include:

[0081] Step S310, Fault Identification.

[0082] The system detects abnormal operating status of the busbar and, based on the current direction of all switches and the associated feeder terminal unit number, performs fault handling and information transmission according to seven logics: non-power supply side fault blocking, non-power supply side fault abnormal handling, load side fault abnormal handling, power supply side grid fault abnormal handling, load side power supply fault abnormal handling, ring mains cabinet internal fault handling, and simultaneous internal and external ring mains cabinet fault handling. Finally, it executes switch change refresh logic. If a switch is activated, a switch change signal is sent to the associated feeder terminal unit, and the third part of the corresponding switch number is refreshed according to the numbering rules.

[0083] Step S320: Fault isolation.

[0084] The system processes interlocking and abnormal information from adjacent feeder terminal units. Based on the adjacent feeder terminal unit number, it locates the corresponding associated switch. According to the current direction of the associated switch, it performs fault isolation operations by following the interlocking signal processing logic, abnormal signal processing logic, and trip relay execution logic. Finally, it executes the switch change refresh logic. If a switch is activated, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0085] Step S330: Network reconstruction.

[0086] If a busbar undervoltage is detected, the undervoltage ring main unit is restored to power according to the internal reconfiguration logic, external reconfiguration signal sending logic, and reconfiguration signal processing logic. Finally, the switch change refresh logic is executed. If a switch is activated, a switch change signal is sent to the associated feeder terminal unit. According to the numbering rules, the third part of the corresponding switch number is refreshed.

[0087] To describe the above steps in more detail, the operations in each step will be further described and illustrated with examples.

[0088] Specifically, the fault identification step S310 can be further divided into the following processes:

[0089] 1) Fault identification logic ① (non-power supply side fault blocking logic): If any one of the following operating conditions is detected: low voltage, overvoltage, low frequency, or overfrequency on the bus or overcurrent on any switch, if the switch current flows to the bus or there is no current (but there is current on other switches), then a blocking information is sent to the associated FTU. If there is no associated FTU, then no blocking information is sent.

[0090] 2) Fault identification logic ② (non-power supply side grid fault abnormality handling logic): If any one of the following operating conditions is detected: low voltage, overvoltage, low frequency, or overfrequency on the bus or any switch overcurrent, if the switch current flows out of the bus and the switch has an associated FTU, the abnormal information of the switch is sent to its associated FTU and the trip relay T1 is triggered.

[0091] 3) Fault identification logic ③ (load-side fault abnormality handling logic): If any one of the following operating conditions is detected: low voltage, overvoltage, low frequency, or overfrequency on the bus or any switch overcurrent, if the switch current flows out of the bus, and if there is no associated FTU or the associated FTU is in the open state, then the switch will trip and be locked.

[0092] 4) Fault identification logic ④ (Power supply side grid fault abnormality handling logic): If any one of the following operating conditions is detected: low voltage, overvoltage, low frequency, or overfrequency on the bus or any switch overcurrent, if there is no current in all switches and the waveform shows that the current flowed to the bus before the fault and there is an associated FTU, then the abnormal information of the switch will be sent to its associated FTU and the trip relay T1 will be triggered.

[0093] 5) Fault identification logic ⑤ (load-side power supply fault abnormal handling logic): If any one of the following operating conditions is detected: low voltage, overvoltage, low frequency, or overfrequency on the bus or overcurrent on any switch, if there is no current on all switches and the waveform shows that the current flowed to the bus before the fault and there is no associated FTU, then the switch will be tripped and locked.

[0094] 6) Fault identification logic⑥ (Fault handling logic within the ring main unit): If the differential current of each switch bus tie exceeds the limit, all switches in the ring main unit will trip and be locked. If the switch current flows to the bus or there is no current, the lockout information will be sent to the associated FTU. If there is no associated FTU, no lockout information will be sent.

[0095] 7) Fault identification logic ⑦ (simultaneous fault handling logic of ring main unit and external circuit): If the differential current of each switch bus tie exceeds the limit, all switches of the ring main unit will trip and be locked. If the switch current flows out of the bus and the switch has an associated FTU, the abnormal information of the switch will be sent to its associated FTU.

[0096] 8) Execute switch change refresh logic: If there is a switch action, send a switch change signal to the associated FTU, and refresh the third part of the corresponding switch number (associated FTU switch status) according to the numbering rules.

[0097] like Figure 5 As shown, if a fault occurs on the power grid side.

[0098] 1) When the fault is at the remote end of the power grid, switch A12-003-1 conforms to fault identification logic ② and sends an abnormal signal to FTU03. Switch A11-001-1 conforms to fault identification logic ① and sends a blocking signal to FTU01. Switches A01-000-0, A02-000-0, A03-000-0 and A04-000-0 conform to fault identification logic ① and do not send messages.

[0099] 2) When the fault is adjacent to the grid side, switch A12-003-0 conforms to fault identification logic ③. Because the adjacent switch is in the open state, this switch (A12-003-0) trips and is blocked. A11-001-1 conforms to fault identification logic ① and sends a blocking signal to FTU01. Switches A01-000-0, A02-000-0, A03-000-0, and A04-000-0 conform to fault identification logic ① and do not send messages.

[0100] 3) When a line fault occurs in the power supply section on the grid side, A11-001-1 conforms to fault identification logic ④ and sends an abnormal signal to FTU01.

[0101] like Figure 6 As shown, if a fault occurs on the load side.

[0102] 1) When the fault is on the load side, switches A11-001-1 and A12-003-1 meet the fault identification logic ① and send blocking signals to FTU01 and FTU03 respectively. Switches A02-000-0, A03-000-0, and A04-000-0 meet the fault identification logic ① and do not send any messages. Switch A01-000-0 meets the fault identification logic ③, trips this switch (A01-000-0), and is blocked.

[0103] 2) When there is a power supply failure on the load side, switches A11-001-1 and A12-003-1 are in the open state and are powered by the power supply under switch A01-000-0. Switch A01-000-0 meets the fault identification logic ⑤, while switches A01-000-0, A02-000-0, A03-000-0 and A04-000-0 meet the fault identification logic ① and no message is sent.

[0104] like Figure 7 As shown, if a fault occurs inside the ring main unit...

[0105] 1) If only the busbar fails, switches A11-001-1, A12-003-1, A01-000-0, A02-000-0, A03-000-0 and A04-000-0 meet the fault identification logic ⑥. All switches will trip and be locked. Switches A11-001-1 and A12-003-1 will send lockout signals to FTU01 and FTU03 respectively.

[0106] 2) When a fault occurs simultaneously on the busbar and adjacent lines, switches A11-001-1, A01-000-0, A02-000-0, A03-000-0, and A04-000-0 meet the fault identification logic ⑥, and switch A12-003-1 meets the load fault identification logic ⑦. All switches trip and are locked. Switch A11-001-1 sends a lockout signal to FTU01. Switch A12-003-1 sends an abnormal signal to FTU03.

[0107] Specifically, step S320, fault isolation, can be divided into the following processes:

[0108] 1) Fault isolation logic ① (lockout signal processing logic): If a lockout signal is received, clear the trip relay T1. For example... Figure 8 As shown in the diagram, the remote fault blocking signal processing is illustrated. When FTU02 receives the blocking signal from FTU03, it clears the trip relay T1 of switch A12-003-1.

[0109] 2) Fault Isolation Logic ② (Abnormal Signal Handling Logic): If an abnormal signal is received, the corresponding associated switch is located based on the FTU number from which the abnormal signal originates. If the switch current flows out of the bus or there is no current, the switch trips and is locked. For example... Figure 8 As shown in the diagram, the abnormal signal processing of adjacent line faults is illustrated. When FTU02 receives the abnormal signal from FTU03, it finds the associated switch A12-003-1 according to the FTU number 03. The switch current flows out of the bus, and the switch A12-003-1 is tripped.

[0110] 3) Fault Isolation Logic ③ (Trip Relay Execution Processing Logic): After the trip relay T1 time expires, the corresponding switch trips. For example... Figure 8 As shown, the trip relay processing extended isolation is illustrated. FTU02 did not receive any signal from FTU03. After the T1 time of the trip relay A12-003-1 expires, the switch A12-003-1 will trip.

[0111] 4) Execute switch change refresh logic: If there is a switch action, send a switch change signal to the associated FTU, and refresh the third part of the corresponding switch number (associated FTU switch status) according to the numbering rules.

[0112] Specifically, step S330, network reconstruction, can be divided into the following processes:

[0113] 1) Reconfiguration Logic ① (Reconfiguration Logic within the Ring Main Unit): The FTU detects a busbar voltage loss and the presence of an open, unblocked switch. Time relay T2 is activated. After time relay T2 expires, the switch is closed. If multiple such switches exist, the switch with voltage on its other side is selected for execution; if all switches have voltage or none have voltage, one is selected. Figure 9 As shown, the processing logic inside the ring main unit is as follows: when the busbar loses voltage, switch A11-001-1 is opened and not locked, and time relay T2 is activated. After the time relay T2 expires, switch A11-001-1 is closed.

[0114] 2) Reconfiguration Logic ② (External Reconfiguration Signal Sending Logic): When the FTU detects a bus voltage loss, and there is a switch associated with that FTU, but the switch is in an open state, a reconfiguration signal is sent to that associated FTU. If there are multiple switches with associated FTUs, any one of them is selected. For example... Figure 9 As shown, the external reconfiguration signal sending logic is as follows: the bus loses voltage, switch A11-001-0 is merged, but according to the number, the adjacent switch is in the open state, so a reconfiguration signal is sent to the associated switch FTU (FTU01).

[0115] 3) Reconstruction Logic ③ (Reconstruction Signal Processing Logic): When the FTU receives the reconstruction signal, it determines whether there is voltage on the bus. If there is voltage, it determines whether the associated switch is closed based on the FTU number of the source signal. If the switch is in the open state and not blocked, it starts time relay T2. After time relay T2 expires, the switch is closed. For example... Figure 9 As shown, the reconfiguration signal processing logic receives the reconfiguration signal from FTU02 and the bus is energized. Based on the FTU02 number 02, it indexes the associated switch A12-002-1, confirms that it is in the open state, and starts the time relay T2. After the time relay T2 expires, the switch is closed.

[0116] 4) Execute switch change refresh logic: If there is a switch action, send a switch change signal to the associated FTU, and refresh the third part of the corresponding switch number (associated FTU switch status) according to the numbering rules.

[0117] It is conceivable that, since the detection process is continuous and sustained, steps S310 to S330 will be repeated continuously during operation to maintain the detection state.

[0118] According to embodiments of other aspects of this application, see reference to Figure 10 and Figure 11 It provides two typical power distribution structures and fault scenarios for the application of distributed protection methods.

[0119] in, Figure 10 As a typical feeder case 1, in the initial state, ring main unit 1 and ring main unit 2 are powered from the left side, and ring main unit 3 is powered from the right side. The switches are numbered according to the numbering rules, and four fault scenarios are set: K1 occurs in the line between switches A01-002-1 and A11-001-1, K2 occurs on the bus of ring main unit 1, K3 occurs in the line between switches A12-003-1 and A11-002-1, and K4 occurs in the line downstream of switch A01-000-0 of ring main unit 1.

[0120] Figure 11 In typical feeder case 2, ring main unit 1 and ring main unit 2 are powered from the left side in the initial state, and ring main unit 3 is powered from the right side. The two incoming switches of ring main unit 2 are disconnected and powered by the downstream distributed power source. Set up a fault scenario, K5 occurs on the line downstream of switch A01-000-0 of ring main unit 2.

[0121] The above Figure 10 and Figure 11 In the described case, FTU01 collects data from both sides of incoming switch A01-002-1 and executes operation logic; FTU02 collects data from switches and busbars in ring main unit 1 and executes operation logic; FTU03 collects data from switches and busbars in ring main unit 2 and executes operation logic; FTU04 collects data from switches and busbars in ring main unit 3 and executes operation logic; and FTU05 collects data from both sides of incoming switch A01-004-1 and executes operation logic.

[0122] Another embodiment of the present invention provides a distributed protection method based on fault scenario K1, which can be described as follows:

[0123] a) Fault identification

[0124] FTU01 detected an overcurrent in switch A01-002-1, which meets the fault identification logic ②. It then sent an abnormal signal to FTU02 and triggered trip relay T1.

[0125] FTU02 detected low voltage on the busbar. Before the fault in switch A11-001-1, the current flowed towards the busbar, which conforms to fault identification logic ④. It then sent an abnormal signal to FTU01 and triggered trip relay T1.

[0126] b) Fault isolation

[0127] FTU01 receives an abnormal signal from FTU02. According to the number index, the corresponding switch A01-002-1 meets the fault isolation logic ②. Switch A01-002-1 trips and is locked.

[0128] FTU02 receives an abnormal signal from FTU01. According to the number index, the corresponding switch A11-001-1 meets the fault isolation logic ②. Switch A11-001-1 trips and is locked. The switch number is revised after the corresponding switch trips.

[0129] c) Network Restructuring

[0130] The 02 busbar of the ring main unit is undervoltage, and the switch A12-004-0 shows that the adjacent switch is in the open state. According to the number index, a reconfiguration signal is sent to FTU04.

[0131] FTU04 receives the reconfiguration signal from FTU03. Based on the index number, it retrieves the corresponding switch A11-003-1, confirms it is in the open state, and activates time relay T2. After time relay T2 expires, the switch is closed. The switch number is then revised after the corresponding switch trips.

[0132] The result after reconstruction is as follows Figure 12 As shown, ring main unit 1, ring main unit 2 and ring main unit 3 are all powered by the power supply on the right.

[0133] Another embodiment of the present invention provides a K2 distributed protection based on fault scenarios, which can be described as follows:

[0134] a) Fault identification

[0135] FTU01 detected an overcurrent in switch A01-002-1, which meets the fault identification logic ②. It then sent an abnormal signal to FTU02 and triggered trip relay T1.

[0136] FTU02 detected that the bus tie differential exceeded the limit. All switches met the fault identification logic ⑥, and all switches tripped and were locked, sending lockout signals to FTU01 and FTU03 respectively. The switch numbers were revised after the corresponding switches tripped.

[0137] b) Fault isolation

[0138] FTU01 receives a blocking signal from FTU02 and cancels the trip relay T1 according to the number index, keeping switch A01-002-1 in the closed state.

[0139] c) Network Restructuring

[0140] The 02 busbar of the ring main unit is undervoltage, and the switch A12-004-0 shows that the adjacent switch is in the open state. According to the number index, a reconfiguration signal is sent to FTU04.

[0141] FTU04 receives the reconfiguration signal from FTU03. Based on the index number, it retrieves the corresponding switch A11-003-1, confirms it is in the open state, and activates time relay T2. After time relay T2 expires, the switch is closed. The switch number is then revised after the corresponding switch trips.

[0142] The result after reconstruction is as follows Figure 13 As shown, ring main unit 1 is de-energized, while ring main units 2 and 3 are both powered by the power source on the right.

[0143] Another embodiment of the present invention provides a K3 distributed protection based on a fault scenario, the process of which includes:

[0144] a) Fault identification

[0145] FTU01 detected an overcurrent in switch A01-002-1, which meets the fault identification logic ②. It then sent an abnormal signal to FTU02 and triggered trip relay T1.

[0146] FTU02 detected an overcurrent in switch A11-001-1, with current flowing to the bus, which conforms to fault identification logic ①, and sent a lockout signal to FTU01;

[0147] FTU02 detected an overcurrent in switch A11-003-1, with current flowing out of the bus, which meets the fault identification logic ②. It then sent a lockout signal to FTU03 and triggered trip relay T1.

[0148] FTU03 detected low voltage on the busbar. Before the fault in switch A11-002-1, the current flowed towards the busbar, which conforms to fault identification logic ④. It then sent an abnormal signal to FTU02 and triggered trip relay T1.

[0149] b) Fault isolation

[0150] FTU01 receives a blocking signal from FTU02 and cancels the trip relay T1 according to the number index, keeping switch A01-002-1 in the closed state.

[0151] FTU02 received an abnormal signal from FTU02. According to the number index, the current direction of switch A11-001-1 is flowing to the bus, which does not meet the fault isolation logic ②. Therefore, switch A11-001-1 is kept closed.

[0152] FTU02 received an abnormal signal from FTU03. According to the number index, the corresponding switch A12-003-1 meets the fault isolation logic ②. Switch A12-003-1 trips and is locked.

[0153] FTU03 received an abnormal signal from FTU02. According to the number index, the corresponding switch A11-002-1 meets the fault isolation logic ②. Switch A11-002-1 trips and is locked.

[0154] The switch number is revised after the corresponding switch trips.

[0155] c) Network Restructuring

[0156] The 02 busbar of the ring main unit is undervoltage, and the switch A12-004-0 shows that the adjacent switch is in the open state. According to the number index, a reconfiguration signal is sent to FTU04.

[0157] FTU04 receives the reconfiguration signal from FTU03. Based on the index number, it retrieves the corresponding switch A11-003-1, confirms it is in the open state, and activates time relay T2. After time relay T2 expires, the switch is closed. The switch number is then revised after the corresponding switch trips.

[0158] The result after reconstruction is as follows Figure 14 As shown, ring main unit 1 is powered by the power supply on the left, while ring main units 2 and 3 are both powered by the power supply on the right.

[0159] Another embodiment of the present invention provides a K4 distributed protection based on a fault scenario, the process of which includes:

[0160] a) Fault identification

[0161] FTU01 detected an overcurrent in switch A01-002-1, which meets the fault identification logic ②. It then sent an abnormal signal to FTU02 and triggered trip relay T1.

[0162] FTU02 detected an overcurrent in switch A11-001-1, with current flowing to the bus, which conforms to fault identification logic ①, and sent a lockout signal to FTU01;

[0163] FTU02 detected an overcurrent in switch A01-000-0, with current flowing out of the bus, which meets the fault identification logic ③. The switch (A01-000-0) was tripped and locked.

[0164] The switch number is revised after the corresponding switch trips.

[0165] b) Fault isolation

[0166] FTU01 receives a blocking signal from FTU02 and cancels the trip relay T1 according to the number index, keeping switch A01-002-1 in the closed state.

[0167] FTU02 received an abnormal signal from FTU02. According to the number index, the current direction of switch A11-001-1 is flowing to the bus, which does not meet the fault isolation logic ②. Therefore, switch A11-001-1 is kept closed.

[0168] c) Network Restructuring

[0169] Not involved.

[0170] After processing, the result is as follows Figure 15 As shown, ring main unit 1 and ring main unit 2 are powered by the power supply on the left, while ring main unit 3 is powered by the power supply on the right.

[0171] Another embodiment of the present invention provides a K5 distributed protection based on fault scenarios, the process of which includes:

[0172] a) Fault identification

[0173] FTU03 detected low voltage on busbar 2 of the ring main unit, and the current flowed to the busbar before the fault of switch A01-000-0, with no associated FTU. This meets the fault handling logic 6, so switch A01-000-0 is tripped and locked.

[0174] b) Fault isolation

[0175] none

[0176] c) Network Restructuring

[0177] FTU03 detected a voltage loss on the 03 busbar of the ring main unit. There were open and unlocked switches A11-002-1 and A12-004-1. Switch A11-002-1 was selected to start time relay T2. After the time relay T2 expired, switch A11-002-1 was closed.

[0178] The switch number is revised after the corresponding switch trips.

[0179] The result after reconstruction is as follows Figure 16 As shown, ring main unit 1 and ring main unit 2 are powered by the power supply on the left, while ring main unit 3 is powered by the power supply on the right.

[0180] Another embodiment of this application provides a distributed protection system for distribution network feeders, such as... Figure 17As shown, the distributed protection system 20 for the power distribution network feeder includes: a rule-making module 201, an information acquisition module 202, and a logic judgment module 203.

[0181] The rule-making module 201 can use the feeder terminal unit, with the ring main unit and the incoming switch as the processing unit, to formulate the numbering rules of the control switch of the feeder terminal unit and establish communication between the associated feeder terminal units.

[0182] Information acquisition module 202 is capable of acquiring voltage, current, and frequency values ​​of switches and busbars within the ring main unit;

[0183] The logic judgment module 203 can perform logical judgments based on the voltage, current, and frequency values ​​of the switches and buses of the information acquisition module, according to preset fault identification logic, fault isolation logic, and network reconstruction logic, and complete the interaction of inter-feed terminal unit blocking information, abnormal information, and reconstruction information.

[0184] The embodiments of this application use FTUs, with ring main units and incoming switches as processing units, to formulate numbering rules for FTU control switches, establish associated FTU communication, and perform logical judgments according to the set fault identification logic, fault isolation logic and network reconstruction logic based on the collected voltage, current and frequency values ​​of switches and buses in the ring main unit. This completes the interaction of inter-FTU interlocking information, abnormal information and reconstruction information, thereby realizing fault isolation and network reconstruction.

[0185] Furthermore, when formulating rules, the rule-making module 201 can specifically divide the rules into the following three categories:

[0186] The switches in the ring main unit are numbered by themselves, and the numbering consists of three digits. The switch numbers in the ring main unit cannot be repeated.

[0187] The associated feeder terminal unit number is the feeder terminal unit number to which the external switch of the ring main unit adjacent to the control switch of the feeder terminal unit belongs. The feeder terminal unit number is a three-digit number, which is uniformly set according to a power distribution feeder, and the number cannot be repeated within a feeder. If the control switch of the feeder terminal unit has no adjacent external switch of the ring main unit and its corresponding feeder terminal unit, the number is 000.

[0188] The associated feeder terminal unit switch status is 0, indicating open and 1, indicating closed. The associated feeder terminal unit switch refers to the external switch of the ring main unit adjacent to the feeder terminal unit control switch. If the feeder terminal unit control switch has no adjacent external switch of the ring main unit and its corresponding feeder terminal unit, then this number is 0.

[0189] Furthermore, the logic judgment module 202 specifically includes:

[0190] The fault identification unit can detect abnormal operating status of the bus. Based on the current direction of all switches and the associated feeder terminal unit number, it performs fault processing and information transmission according to seven logics: non-power supply side fault blocking, non-power supply side fault abnormal handling, load side fault abnormal handling, power supply side grid fault abnormal handling, load side power supply fault abnormal handling, ring network cabinet internal fault handling, and simultaneous internal and external fault handling. Finally, it executes the switch change refresh logic. If a switch is activated, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0191] The fault isolation unit processes the blocking and abnormal information sent by the adjacent feeder terminal units. Based on the adjacent feeder terminal unit number, it finds the corresponding associated switch. Based on the current direction of the associated switch, it performs fault isolation operation according to the blocking signal processing logic, abnormal signal processing logic, and trip relay execution logic. Finally, it executes the switch change refresh logic. If there is a switch action, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0192] The network reconfiguration unit detects bus voltage loss and restores power to the under-voltage ring main unit according to the reconfiguration logic within the ring main unit, the external reconfiguration signal sending logic, and the reconfiguration signal processing logic. Finally, it executes the switch change refresh logic. If there is a switch action, it sends a switch change signal to the associated feeder terminal unit and refreshes the third part of the corresponding switch number according to the numbering rules.

[0193] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A power distribution network feeder distributed protection method, characterized by, The method comprises the following steps: Using feeder terminal units, taking ring main units and incoming switch as processing units, formulating the numbering rule of feeder terminal unit control switch, establishing the communication of associated feeder terminal unit; Collecting the voltage, current and frequency values of switch and bus in ring main unit; Based on the voltage, current and frequency values of switch and bus, logical judgment is made according to preset fault identification logic, fault isolation logic and network reconstruction logic to complete the interaction of blocking information, abnormal information and reconstruction information between feeder terminal units, including: fault identification, detecting abnormal working state of bus, according to the current direction of all switches and the number of associated feeder terminal unit, seven logics of non-power side fault blocking, non-power side fault abnormal processing, load side fault abnormal processing, power side power grid fault abnormal processing, load side power fault abnormal processing, ring main unit fault processing and ring main unit and external fault processing are used for fault processing and information sending, and finally switch change refresh logic is executed, if there is switch action, switch change signal is sent to associated feeder terminal unit, and the third part of corresponding switch number is refreshed according to the numbering rule; fault isolation, processing blocking information and abnormal information sent by adjacent feeder terminal unit, finding corresponding associated switch according to the number of adjacent feeder terminal unit, according to the current direction of the associated switch, using blocking signal processing logic, abnormal signal processing logic and trip relay execution processing logic to perform fault isolation operation, and finally executing switch change refresh logic, if there is switch action, sending switch change signal to associated feeder terminal unit, and refreshing the third part of corresponding switch number according to the numbering rule; network reconstruction, detecting loss of voltage of bus, and according to ring main unit reconstruction logic, external reconstruction signal sending logic and reconstruction signal processing logic to restore power supply of loss of voltage ring main unit, and finally executing switch change refresh logic, if there is switch action, sending switch change signal to associated feeder terminal unit, and refreshing the third part of corresponding switch number according to the numbering rule.

2. The method of claim 1, wherein, The numbering rule of feeder terminal unit control switch, which is divided into three parts, comprises: Self-numbering of switch of ring main unit, the self-numbering of switch of ring main unit is composed of three digits, and the self-numbering of switch in ring main unit cannot be repeated; Number of associated feeder terminal unit, the number of associated feeder terminal unit is three digits, which is uniformly set according to one distribution feeder, and the numbers in one feeder cannot be repeated; if there is no adjacent ring main unit switch and its belonging feeder terminal unit, the number is 000; Switch state of associated feeder terminal unit, 0 represents disconnection, and 1 represents connection; the switch state of associated feeder terminal unit refers to the adjacent ring main unit switch of feeder terminal unit control switch, and if there is no adjacent ring main unit switch and its belonging feeder terminal unit, the number is 0.

3. The method of claim 1, wherein, The fault identification step, the non-power supply side fault lockout, the non-power supply side fault abnormality processing, the load side fault abnormality processing, the power supply side power grid fault abnormality processing, the load side power supply fault abnormality processing, the ring network cabinet internal fault processing, and the ring network cabinet internal and external simultaneous fault processing, comprise: The non-power supply side fault lockout comprises: detecting any one of bus low voltage, overvoltage, low frequency, over frequency or any switch overcurrent, if the switch current flows to the bus or has no current, sending the lockout information to the associated feeder terminal unit, and not sending to the unassociated feeder terminal unit; The non-power supply side power grid fault abnormality processing comprises: detecting any one of bus low voltage, overvoltage, low frequency, over frequency or any switch overcurrent, if the switch current flows out of the bus and the switch is associated with the feeder terminal unit, sending the abnormality information of the switch to the associated feeder terminal unit, and triggering the trip relay; The load side fault abnormality processing comprises: detecting any one of bus low voltage, overvoltage, low frequency, over frequency or any switch overcurrent, if the switch current flows out of the bus, if there is no associated feeder terminal unit or the state of the associated feeder terminal unit is off, tripping the switch and locking; The load side power supply fault abnormality processing comprises: detecting any one of bus low voltage, overvoltage, low frequency, over frequency or any switch overcurrent, if all switches have no current and the recorded wave shows that the current flows to the bus before the fault, the switch is tripped and locked; The ring network cabinet internal fault processing comprises: detecting the bus differential current of each switch, executing the trip and lock of all switches of the ring network cabinet, if the switch current flows to the bus or has no current, sending the lockout information to the associated feeder terminal unit, and not sending to the unassociated feeder terminal unit; The ring network cabinet and external simultaneous fault processing comprises: detecting the bus differential current of each switch, executing the trip and lock of all switches of the ring network cabinet, if the switch current flows out of the bus and the switch is associated with the feeder terminal unit, sending the abnormality information of the switch to the associated feeder terminal unit.

4. The method of claim 1, wherein, The fault isolation step, the lockout signal processing logic, the abnormality signal processing logic and the trip relay execution processing logic, comprise: The lockout signal processing logic, if the lockout signal is accepted, clearing the trip relay; The abnormality signal processing logic, if the abnormality signal is accepted, finding the corresponding associated switch according to the feeder terminal unit number of the abnormality signal source, if the switch current flows out of the bus or has no current, the switch is tripped and locked; The trip relay execution processing logic, after the time of the trip relay, tripping the corresponding switch.

5. The method of claim 1, wherein, The network reconstruction step, the ring network cabinet internal reconstruction logic, the external reconstruction signal sending logic and the reconstruction signal processing logic, comprise: The ring network cabinet internal reconstruction logic, the feeder terminal unit detecting the bus voltage loss, there being a switch that is off and not locked, starting the time relay, after the time of the time relay, closing the switch, if there are multiple such switches, selecting the switch on the side with voltage to execute, if all have voltage or all have no voltage, selecting one of them; The external reconfiguration signal sending logic, when the feeder terminal unit detects that the bus loses voltage, sends a reconfiguration signal to the associated feeder terminal unit if there is a switch associated with the feeder terminal unit and the switch state of the associated switch is off; The reconfiguration signal processing logic, when the feeder terminal unit receives the reconfiguration signal, judges whether the bus has voltage, and if so, judges whether the associated switch is closed according to the feeder terminal unit number of the source signal, and if the switch is open and not locked, starts a time relay, and after the time relay time is up, closes the switch.

6. A distribution feeder protection system for an electrical distribution network, characterized by Comprise: The rule making module can use the feeder terminal unit to make a number rule of the feeder terminal unit control switch with the ring main unit and the incoming line switch as a processing unit, and establish an associated feeder terminal unit communication; The information acquisition module can acquire the voltage, current and frequency values of the switch and the bus in the ring main unit; The logic judgment module can judge the voltage, current and frequency values of the switch and the bus in the information acquisition module according to the preset fault identification logic, fault isolation logic and network reconfiguration logic, complete the locking information, abnormal information and reconfiguration information interaction between the feeder terminal units, including: the fault identification unit can detect the abnormal working state of the bus, and according to the current direction of all switches and the associated feeder terminal unit number, seven logics of non-power side fault locking, non-power side fault abnormal processing, load side fault abnormal processing, power side power grid fault abnormal processing, load side power fault abnormal processing, ring main unit fault processing and ring main unit and external fault processing are used for fault processing and information sending, and finally the switch change refreshing logic is executed, if there is switch action, the switch change signal is sent to the associated feeder terminal unit, and the third part of the corresponding switch number is refreshed according to the number rule; the fault isolation unit processes the locking information and abnormal information sent by the adjacent feeder terminal unit, finds the corresponding associated switch according to the adjacent feeder terminal unit number, and processes the locking signal processing logic, the abnormal signal processing logic and the trip relay according to the current direction of the associated switch, and finally executes the switch change refreshing logic, if there is switch action, the switch change signal is sent to the associated feeder terminal unit, and the third part of the corresponding switch number is refreshed according to the number rule; the network reconfiguration unit detects that the bus loses voltage, and restores power supply of the voltage loss ring main unit according to the ring main unit reconfiguration logic, the external reconfiguration signal sending logic and the reconfiguration signal processing logic, and finally executes the switch change refreshing logic, if there is switch action, the switch change signal is sent to the associated feeder terminal unit, and the third part of the corresponding switch number is refreshed according to the number rule.

7. The system of claim 6, wherein, The rule making module makes the following three rules when making the rules: The switch self-numbering of the ring main unit, the switch self-numbering consists of three digits, and the switch self-numbering in the ring main unit cannot be repeated; The associated feeder terminal unit number controls the switch adjacent to the ring main unit switch outside the feeder terminal unit to which the number belongs. The associated feeder terminal unit number is a three-digit number, which is uniformly set according to a power distribution feeder, and the number in a feeder cannot be repeated. If the feeder terminal unit control switch has no adjacent ring main unit switch outside the feeder terminal unit and the feeder terminal unit to which the number belongs, the number is 000. The associated feeder terminal unit switch state, 0 indicates open, 1 indicates closed, the associated feeder terminal unit switch refers to the ring main unit switch adjacent to the feeder terminal unit control switch, and if the feeder terminal unit control switch has no adjacent ring main unit switch outside the feeder terminal unit and the feeder terminal unit to which the number belongs, the number is 0.

8. A computer readable storage medium storing computer executable instructions for performing the method of any one of claims 1 to 5.

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