Distributed feeder fault processing and load recovery method for multi-segment looped network

Abstract

The invention provides a distributed feeder fault processing and load recovery method for a multi-segment looped network, relates to the technical field of feeder automation of a power distribution network, and is used for realizing rapid positioning and isolation of faults and recovering loads according to the sequence of the electrical distances from load nodes in a downstream area of the faults to contact switch nodes from near to far. A 10kV outgoing line switch of a transformer substation and an intelligent terminal unit STU of each group of looped network are arranged, overcurrent detection elements are arranged in the intelligent terminal units STU to detect information of current flowing through each switch and on-off states of the switches in real time, and meanwhile information exchange with the adjacent intelligent terminal units STU is achieved through an optical fiber peer-to-peer communication network. All the intelligent terminal units cooperate and communicate with one another, the fault position is judged through information sets and fault criteria, a command is sent to disconnect switches at the two ends of the fault to isolate the fault, loads are recovered one by one according to the sequence of being close to the electrical distance of a contact switch node, the steps and sequence of load recovery are defined, and the load recovery efficiency is improved. The method can ensure that the load near the interconnection switch is recovered to the maximum extent, and has the characteristic of low feeder line loss.

Description

Technical Field

[0001] The invention relates to the technical field of distribution network feeder automation, in particular to a distributed feeder fault processing and load recovery method for a multi-segment ring network applicable to a multi-segment multi-interconnection ring network. Background Art

[0002] With the increase of urban power supply load and the improvement of power supply reliability requirements, in order to improve line utilization, a third or fourth power supply is added to form a multi-power supply connection on the basis of the conventional dual-power single-ring network connection mode. Due to the changeable operation mode of the actual distribution network, compared with the traditional ring network structure, the multi-connection distribution network has more load transfer paths and more flexible operation modes, and has the advantages of high efficiency and good economy. With the increase of interconnection switches, the operation mode of the distribution network has become complicated. While providing multiple power supply recovery paths for the distribution network after fault isolation, it also brings the trouble of how to find the optimal recovery path in time.

[0003] There are two main types of feeder automation systems that are widely used at present: one is the local feeder automation system that cooperates with the substation reclosing switch and the section switch, but it can only work when a fault occurs, and the fault handling process is strictly carried out according to the pre-set principles, and the fault handling time is relatively long; the other is the centralized distribution network automation system, but it requires the participation of the distribution automation master station and relies on the communication network to monitor the distribution network in real time. Summary of the invention

[0004] The technical problem to be solved by the present invention is to realize rapid fault location and isolation in a multi-segment multi-interconnection ring network distribution network, and to restore the load in order from near to far according to the electrical distance between the load nodes in the downstream area of ​​the fault and the interconnection switch nodes, thereby providing a distributed feeder fault processing and load recovery method for a multi-segment ring network.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a distributed feeder fault processing and load recovery method of a multi-segment ring network, which is applied to a distributed feeder automation system, wherein the distributed feeder automation system includes a substation 10kV outgoing line switch, multiple groups of intelligent terminal units STU and an optical fiber peer-to-peer communication network. The substation 10kV outgoing line switch and the intelligent terminal unit STU are both equipped with an overcurrent detection element for real-time detection of current information and switch opening and closing status. The optical fiber peer-to-peer communication network is used to realize information exchange with adjacent intelligent terminal units STU. The substation 10kV outgoing line switch and each group of intelligent terminal units of the ring network are respectively regarded as a node. The method comprises the following steps: Step 1, forming an upstream and downstream relationship information table of each node, the table format is shown in Table 1, the upstream and downstream relationship information table at least includes the name of the current node, the address of the current node, the name of the adjacent node, the address of the adjacent node, the upstream and downstream relationship between the current node and the adjacent node, the name of the current node connection switch, whether the current node connection switch is closed, the name of the adjacent node connection switch, whether the adjacent node connection switch is closed, whether the current node is a power supply node, whether the current node is a tie switch node, and whether the current node is a terminal load node; Table 1 is the format template of the upstream and downstream relationship information table; Table 1 Upstream and downstream relationship information table Step 2: The intelligent terminal unit of each node regularly collects the current value of the upstream switch in all the lines of the node, where the line refers to the line between the connecting switch connecting the node and the adjacent downstream node and the connecting switch connecting the adjacent downstream node and the node, and requires the intelligent terminal unit STU of the node where the downstream connecting switch of the line is located to transmit the current value of the downstream connecting switch to it, compares the current value of the upstream connecting switch and the downstream connecting switch of each section of the line, and determines whether the section of the line has a fault according to the predetermined short-circuit current criterion of each line; Step 3: If a fault occurs, the intelligent terminal unit STU at the node where the upstream connection switch of the faulty section is located disconnects the upstream connection switch, and notifies the intelligent terminal unit STU at the node where the downstream connection switch is located to disconnect the downstream connection switch to eliminate the fault; Step 4: Starting from the intelligent terminal unit STU at the node where the switch is located downstream of the fault section, search for load nodes and tie switches in each branch downstream of the fault section; Step 5: The intelligent terminal units STU of the tie switch nodes that can be used to restore the non-fault power outage section communicate with each other, obtain the load information table information to be restored, compare the available remaining capacity of each tie switch node, and select the tie switch with the largest available remaining capacity as the tie switch for restoring power supply; Step 6: If the remaining capacity of the tie switch is greater than the total load to be restored, close the tie switch to restore power to all loads in the non-fault power outage section. Otherwise, go to step 7; Step 7: Starting from the intelligent terminal unit STU of the contact switch node determined in step 5, search for adjacent nodes to which power supply can be restored one by one, and restore their power supply.

[0006] Furthermore, in step 1, the specific method for forming the upstream and downstream relationship information table is as follows: when the intelligent terminal unit STU is put into operation, the upstream and downstream relationship information table is filled in the intelligent terminal unit STU of each node according to the electrical connection relationship of the distribution network, so as to form the initial upstream and downstream relationship information table of the intelligent terminal unit STU of each node; during the operation of the distribution network, the opening and closing status of each switch is searched in real time and regularly from the intelligent terminal unit STU of the power supply node to each branch and to the intelligent terminal unit STU of the downstream node one by one, and the upstream and downstream relationship information table of the intelligent terminal unit STU of each node is modified according to the real-time changes.

[0007] Furthermore, in step 4, the search method for searching the load nodes and tie switches from the STU where the downstream switch of the fault section is located to each branch downstream of the fault section is: Find the intelligent terminal unit STU of all nodes connected to the intelligent terminal unit STU of the node where the switch downstream of the fault section is located in the upstream and downstream relationship information table except the intelligent terminal unit STU of the upstream node of the fault section, and the intelligent terminal unit STU of the node sends a search command to the intelligent terminal unit STU of all nodes connected to it except the intelligent terminal unit STU of the upstream node of the fault section. The intelligent terminal unit STU that receives the search command also sends a search command to the intelligent terminal unit STU of all nodes connected to it except the intelligent terminal unit STU of the upstream node of the fault section, and searches the intelligent terminal unit STU of all nodes downstream of the fault section one by one until all the tie switch nodes and the terminal load nodes are reached. Each searched load node and tie switch node is marked as a node downstream of the fault section, and each searched tie switch is marked as a tie switch that can be used to restore the non-fault power outage section. In the process of searching, a load information table to be restored is gradually formed, and the intelligent terminal unit STU name of each load node to be restored and the load size of the node before the fault are recorded in turn. Table 2 is the format template of the load information table to be restored, and the table format is shown in Table 2: Table 2 Load information table to be restored And send the final record table to the intelligent terminal unit STU of the interconnection switch node connected to the terminal load node.

[0008] Further, in step 7, the specific search method of the tie switch STU starting to search for adjacent nodes that can restore power supply one by one is as follows: for any tie switch that can restore power supply in the load information table to be restored, the intelligent terminal unit STU of the tie switch node sends the available remaining capacity to the adjacent upstream node, and the adjacent upstream node calculates whether the available remaining capacity is less than the load required to restore the node, and records the tie switch node name, the node name searched in sequence, the node load, the dynamic value of the available remaining capacity, and whether the node branch line is traversed, and forms a tie switch node restoreable load node dynamic record table with the record content. Here, Table 3 is a format template of the tie switch node restoreable load node dynamic record table, and the table format is shown in Table 3: Table 3 Dynamic record table of tie switch node recoverable load node If the available remaining capacity is not less than the load required to restore this node, then after deducting the load of this node, the dynamic record table of the recoverable load node of the liaison switch node will continue to be sent to other adjacent nodes of the node. The adjacent nodes continue to calculate whether the available remaining capacity after deducting the load of the previous node is less than the load required to restore this node. The above process is repeated until all nodes in the load information table to be restored have been searched, or the available remaining capacity is less than the load required to restore the node. During the search process, the dynamic record table of the recoverable load node of the liaison switch node is continuously updated, and the record table is passed to the intelligent terminal unit STU required for the newly searched node until a node is searched and the available remaining capacity is less than the load used to restore the node. Then a row of the dynamic record table of the recoverable load node of the liaison switch node is added to the end of the dynamic record table of the recoverable load node of the liaison switch node. The node information is recorded, and the record table information is sent to the intelligent terminal unit STU of the interconnecting switch node. The intelligent terminal unit STU closes the switch according to the name of the downstream switch in the first row of the record table. According to the names of the downstream switches on the branch in the last row of the record table, the intelligent terminal unit STU of the node where the corresponding switch is located is notified to open the downstream switches on the branch. The load of the node cannot be restored by this interconnecting switch. According to each row of nodes except the last row in the record table, a load restoration message is sent to the intelligent terminal unit STU of each row of nodes. The intelligent terminal unit STU of each node records the message. According to the node in the last row of the record table, a load non-restored message is sent to the intelligent terminal unit STU of the node. The intelligent terminal unit STU of the node records the load non-restored message.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention adopts a distributed fault section location and isolation scheme for passive distribution networks based on peer-to-peer communication between intelligent terminal units (STUs). The scheme uses the current comparison at both ends of the line as the principle of fault section location, with high positioning accuracy, strong reliability, speed, sensitivity and selectivity.

[0010] (2) The present invention adopts a distribution network topology information identification and storage solution suitable for distributed control mode. This solution has low requirements for STU data calculation and storage. It only needs to configure basic static network topology information for the intelligent terminal unit STU, and automatically completes topology identification and update during operation to adapt to changes in the distribution network operation mode, reducing manual workload.

[0011] (3) The method adopted by the present invention can quickly restore power supply to all loads in the upstream area of ​​the fault.

[0012] (4) The power supply restoration strategy of the present invention is to restore the loads in the downstream area of ​​the fault one by one in the order of the electrical distance from the tie switch from near to far. This strategy avoids the uncertainty of restoring different load nodes by multiple tie switches in a complex distribution network structure, and also minimizes the amount of calculation to determine the restored load nodes, ensuring that the loads that are close to the tie switch are restored quickly and preferentially, and restoring the power supply of nearby loads to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a flow chart of the fault handling and load recovery method of the present invention.

[0014] Figure 2 Schematic diagram of a multi-segment three-connection ring network of a distribution network in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0016] A distributed feeder fault processing and load recovery method for a multi-segmented ring network described in the present invention is applied to a distributed feeder automation system, wherein the distributed feeder automation system comprises a 10kV outgoing line switch of a substation, multiple groups of intelligent terminal units STU and an optical fiber peer-to-peer communication network. The 10kV outgoing line switch of the substation and the intelligent terminal unit STU are both equipped with an overcurrent detection element for real-time detection of current information and switch opening and closing status. The optical fiber peer-to-peer communication network is used to exchange information with adjacent intelligent terminal units STU. The 10kV outgoing line switch of the substation and each group of intelligent terminal units of the ring network are respectively used as a node, such as Figure 1 The method shown comprises the following steps: Step 1, forming an upstream and downstream relationship information table of each node, wherein the upstream and downstream relationship information table at least includes the name of the node, the address of the node, the name of the adjacent node, the address of the adjacent node, the upstream and downstream relationship between the node and the adjacent node, the name of the node connection switch, whether the node connection switch is closed, the name of the adjacent node connection switch, whether the adjacent node connection switch is closed, whether the node is a power supply node, whether the node is a tie switch node, and whether the node is a terminal load node. During the operation of the distribution network, the local intelligent terminal unit STU automatically updates the upstream and downstream relationship information table of each node intelligent terminal unit STU in real time through the regularly collected local node information and the information collected by communicating with the adjacent intelligent terminal unit STU, thereby ensuring the real-time and accuracy of the upstream and downstream relationship information table of each node intelligent terminal unit STU.

[0017] Step 2, each node intelligent terminal unit regularly collects the current value of the upstream switch in all the lines of the node, and the line refers to the line between the connecting switch connecting the current node and the adjacent downstream node to the connecting switch connecting the adjacent downstream node and the current node, and requires the intelligent terminal unit STU of the node where the downstream connecting switch of the line is located to transmit the current value of the downstream connecting switch to it, compares the current value of the upstream connecting switch and the downstream connecting switch of each section of the line, and determines whether the section of the line is faulty according to the predetermined short-circuit current criterion of each line.

[0018] The intelligent terminal units (STUs) of adjacent nodes communicate with each other regularly to collect and compare the current values ​​at both ends of the line, ensuring the timeliness and accuracy of fault location judgment.

[0019] Step 3: If a fault occurs, the intelligent terminal unit STU at the node where the upstream connection switch of the faulty section is located disconnects the upstream connection switch, and notifies the intelligent terminal unit STU at the node where the downstream connection switch is located to disconnect the downstream connection switch to eliminate the fault.

[0020] The intelligent terminal units STU at both ends of the fault issue commands promptly and accurately to disconnect the switches at both ends of the fault, ensuring that the upstream nodes of the fault remain powered.

[0021] Step 4: Starting from the intelligent terminal unit STU at the node where the switch is located downstream of the fault section, search for load nodes and tie switches in each branch downstream of the fault section.

[0022] The intelligent terminal unit STU where the downstream switch of the fault section is located is searched section by section according to the information of the intelligent terminal unit STU of the adjacent node in the upstream and downstream relationship information table of the intelligent terminal unit STU of each node, ensuring the completeness and speed of the search.

[0023] Step 5: The intelligent terminal units STU of the interconnection switch nodes that can be used to restore the non-fault power outage section communicate with each other, obtain the load information table information to be restored, compare the available remaining capacity of each interconnection switch node, and select the interconnection switch with a large available remaining capacity as the interconnection switch for restoring power supply.

[0024] The strategy of selecting the tie switch with the largest available remaining capacity ensures that power supply to as many loads as possible is restored to the greatest extent possible.

[0025] Step 6: If the remaining capacity of the tie switch is greater than the total load to be restored, close the tie switch to restore power supply to all loads in the non-fault power outage section; otherwise, go to step 7.

[0026] Step 7: Starting from the intelligent terminal unit STU of the contact switch node determined in step 5, search for adjacent nodes to which power supply can be restored one by one, and restore their power supply.

[0027] The loads in the downstream area of ​​the fault are restored one by one in the order of electrical distance from the tie switch from near to far. This strategy avoids the uncertainty of restoring different load nodes by multiple tie switches in a complex distribution network structure, and also minimizes the amount of calculation to determine the restored load nodes, ensuring fast and priority restoration of loads that are close to the tie switch in electrical distance, and restoring power supply to nearby loads to the greatest extent.

[0028] Furthermore, in the step 1, the specific method for forming the upstream and downstream relationship information table is as follows: when the intelligent terminal unit STU is put into operation, the upstream and downstream relationship information table is filled in the intelligent terminal unit STU of each node according to the electrical connection relationship of the distribution network, so as to form the initial upstream and downstream relationship information table of the intelligent terminal unit STU of each node; during the operation of the distribution network, the opening and closing status of each switch is searched in real time and regularly from the intelligent terminal unit STU of the power supply node to each branch and to the intelligent terminal unit STU of the downstream node one by one, and the upstream and downstream relationship information table of the intelligent terminal unit STU of each node is modified according to the real-time changes, thereby ensuring the real-time and accuracy of the upstream and downstream relationship information table of each node STU.

[0029] Furthermore, in step 4, the search method for searching the load nodes and tie switches from the intelligent terminal unit STU where the downstream switch of the fault section is located to each branch downstream of the fault section is: Find the intelligent terminal unit STU node of the node where the downstream switch of the fault section is located in the upstream and downstream relationship information table of all nodes connected to it except the intelligent terminal unit STU of the upstream node of the fault section, and the intelligent terminal unit STU of the node A search command is sent to the intelligent terminal units STU of all nodes connected to it except the intelligent terminal unit STU of the upstream node of the faulty section. The intelligent terminal unit STU that receives the search command also sends a search command to the intelligent terminal units STU of all nodes connected to it except the intelligent terminal unit STU of the upstream node of the faulty section, and searches the intelligent terminal units STU of all nodes downstream of the faulty section one by one until all the interconnecting switch nodes and the terminal load nodes are reached. Each searched load node and interconnecting switch node is marked as a node downstream of the faulty section, and each interconnecting switch searched above is marked as an interconnecting switch that can be used to restore the non-faulty power outage section. In the process of searching, a load information table to be restored is gradually formed, and the intelligent terminal unit STU name and load size of each load node to be restored are recorded in turn, and the final record table is sent to the intelligent terminal unit STU of the interconnecting switch node connected to the terminal load node. The formed table records the load size for subsequent restoration decision-making.

[0030] Furthermore, in step 7, the specific search method for the tie switch STU to start searching for adjacent nodes that can restore power supply one by one is as follows: for any tie switch that can restore power supply in the load information table to be restored, the intelligent terminal unit STU of the tie switch node sends the available remaining capacity to the adjacent upstream node, and the adjacent upstream node calculates whether the available remaining capacity is less than the load required to restore the node, and records the tie switch node name, the node name searched in sequence, the node load, the dynamic value of the available remaining capacity, and whether the node branch line is traversed, and forms a tie switch node restoreable load node dynamic record table with the record content. If the available remaining capacity is not less than the load required to restore the node, then after deducting the load of the node, the tie switch node restoreable load node dynamic record table is continued to be sent to other adjacent nodes of the node, and the adjacent nodes continue to calculate whether the available remaining capacity after deducting the load of the previous node is less than the load required to restore the node, and repeat the above process until all nodes in the load information table to be restored have been searched, or the available remaining capacity is less than the load required to restore the node. In the search process In the process, the dynamic record table of load nodes that can be restored by the contact switch node is continuously updated, and the record table is passed to the intelligent terminal unit STU of the newly searched node until a node is searched, and the available remaining capacity is less than the load required for restoring the node. Then, a row of records of the node information is added to the end of the dynamic record table of load nodes that can be restored by the contact switch node, and the record table information is sent to the intelligent terminal unit STU of the contact switch node. The intelligent terminal unit STU closes the switch according to the name of the downstream switch in the first row of the record table, and notifies the intelligent terminal unit STU of the node where the corresponding switch is located according to the name of the downstream switch on the branch in the last row of the record table, and opens the downstream switch on the branch. The load of the node cannot be restored by this contact switch. According to each row of nodes other than the last row in the record table, a load restoration message is sent to the intelligent terminal unit STU of each row of nodes above, and the intelligent terminal unit STU of each node records the message. According to the node in the last row of the record table, a load non-restored message is sent to the intelligent terminal unit STU of the node, and the intelligent terminal unit STU of the node records the load non-restored message. The dynamic record table tracks the available capacity and traversal conditions to ensure that the nearest load is restored first to avoid overload.

[0031] like Figure 2 As shown, the feeder network is a multi-segment three-tie ring network. There are 11 load nodes and 3 tie switches in the feeder network, and each node is equipped with an intelligent terminal unit STU. The load information of the embodiment is shown in Table 4, and the available margin of the tie switch in the initial state of the embodiment is shown in Table 5: Table 4 Example load information table Table 5: Available residual capacity of tie switch in initial state A distributed feeder fault processing and load recovery method for a multi-segment ring network of the present invention comprises the following processing steps: Step 1: Form an upstream and downstream relationship information table of each node intelligent terminal unit STU. When the intelligent terminal unit STU is put into operation, fill in the upstream and downstream relationship information table of each node intelligent terminal unit STU in each node intelligent terminal unit STU according to the electrical connection relationship of the distribution network as shown in Table 6 to Table 19. The upstream and downstream relationship information table of each node intelligent terminal unit STU is stored in the database of each node; Table 6 Upstream and downstream relationship information table of node 1 Table 7 Upstream and downstream relationship information table of node 2 Table 8 Upstream and downstream relationship information table of node 3 Table 9 Upstream and downstream relationship information table of node 4 Table 10 Upstream and downstream relationship information table of node 5 Table 11 Upstream and downstream relationship information table of node 6 Table 12 Upstream and downstream relationship information table of node 7 Table 13 Upstream and downstream relationship information table of node 8 Table 14 Upstream and downstream relationship information table of node 9 Table 15 Upstream and downstream relationship information table of node 10 Table 16 Upstream and downstream relationship information table of node 11 Table 17 Upstream and downstream relationship information table of node 12 Table 18 Upstream and downstream relationship information table of node 13 Table 19 Upstream and downstream relationship information table of node 14 Step 2: The intelligent terminal unit STU7 collects the current value of the upstream connection switch K0708 in the line 7-8, and requires STU8 to transmit the current value of the downstream connection switch K0807 to it. The intelligent terminal unit STU7 compares the current values ​​of K0708 and K08071. When the current values ​​differ greatly, it is determined that the line 7-8 is faulty. The method for determining whether the other lines are faulty is the same as the method for determining the line 7-8 mentioned above.

[0032] Step 3: When line 7-8 fails, according to step 2, intelligent terminal unit STU7 determines that line 7-8 fails, and intelligent terminal unit STU7 immediately disconnects K0708 and notifies intelligent terminal unit STU8 to disconnect K0807 to eliminate the fault.

[0033] Step 4: A search command is issued from the intelligent terminal unit STU8 where the switch K0807 downstream of the fault section is located to the intelligent terminal unit STU9 on the opposite side of the downstream branch. The intelligent terminal units STU8 and STU9 are marked as downstream nodes of the fault section. The intelligent terminal unit STU9 issues the search command to the intelligent terminal units STU12 and STU10. The intelligent terminal unit STU12 is marked as a contact switch that can be used to restore the non-fault power outage section. The intelligent terminal unit STU10 is marked as a downstream node of the fault section. The intelligent terminal unit STU10 issues the search command to the intelligent terminal unit STU11. The intelligent terminal unit STU11 is marked as a downstream node of the fault section and the search command is issued to the intelligent terminal unit STU14. The intelligent terminal unit STU14 is marked as a contact switch that can be used to restore the non-fault power outage section. In the process of searching, the load information table to be restored in the embodiment is formed, as shown in Table 20: Table 20 Example load information table to be restored Finally, the load information table information to be restored is transmitted to the intelligent terminal unit STU14 of the node where the tie switch adjacent to the intelligent terminal unit STU11 of the terminal load node is located.

[0034] Step 5: The intelligent terminal units STU14 and STU12 of the interconnection switch nodes that can be used to restore the non-fault power outage sections communicate with each other, compare the intelligent terminal units STU14 and STU12 of the interconnection switch nodes, and select the interconnection switch No. 12 with a larger available remaining capacity as the interconnection switch for restoring power supply.

[0035] Step 6: Comparing the remaining capacity of the No. 12 tie switch with the total load in the load information table to be restored, it can be seen that the remaining capacity of the No. 12 tie switch is less than the total load in the load information table to be restored.

[0036] Step 7: The intelligent terminal unit STU12 communicates with STU9 to search whether the load of node 9 can be restored, and continues to search the adjacent nodes 8, 10 and 11 that have not been searched, until the remaining capacity of the terminal load node or the tie switch 12 cannot be used to restore the node, forming a dynamic record table of the restorable load of the tie switch node 12 as follows: Table 21 Dynamic record table of restorable load nodes of No. 12 tie switch node According to the dynamic record table of the load nodes that can be restored by the contact switch node No. 12, the intelligent terminal unit STU12 closes the switch K1209, sends a command to the intelligent terminal unit STU11 to open the switch K1110, and restores the power supply to nodes 8, 9, and 10.

[0037] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A distributed feeder fault handling and load recovery method for a multi-segment ring network, applied to a distributed feeder automation system, the distributed feeder automation system comprising a substation 10kV outlet switch, multiple groups of intelligent terminal units STU and an optical fiber peer-to-peer communication network, the substation 10kV outlet switch and the intelligent terminal unit STU are both equipped with an overcurrent detection element for real-time detection of current information and switch opening and closing status, the optical fiber peer-to-peer communication network is used to exchange information with adjacent intelligent terminal units STU, the substation 10kV outlet switch and each group of intelligent terminal units of the ring network are respectively used as a node, characterized in that: The method comprises the following steps: Step 1, forming an upstream and downstream relationship information table of each node, wherein the upstream and downstream relationship information table at least includes the name of the node, the address of the node, the name of the adjacent node, the address of the adjacent node, the upstream and downstream relationship between the node and the adjacent node, the name of the connection switch of the node, whether the connection switch of the node is closed, the name of the connection switch of the adjacent node, whether the connection switch of the adjacent node is closed, whether the node is a power supply node, whether the node is a tie switch node, and whether the node is a terminal load node; Step 2: The intelligent terminal unit of each node regularly collects the current value of the upstream switch in all the lines of the node, where the line refers to the line between the connecting switch connecting the node and the adjacent downstream node and the connecting switch connecting the adjacent downstream node and the node, and requires the intelligent terminal unit STU of the node where the downstream connecting switch of the line is located to transmit the current value of the downstream connecting switch to it, compares the current value of the upstream connecting switch and the downstream connecting switch of each section of the line, and determines whether the section of the line has a fault according to the predetermined short-circuit current criterion of each line; Step 3: If a fault occurs, the intelligent terminal unit STU at the node where the upstream connection switch of the faulty section is located disconnects the upstream connection switch, and notifies the intelligent terminal unit STU at the node where the downstream connection switch is located to disconnect the downstream connection switch to eliminate the fault; Step 4: Starting from the intelligent terminal unit STU at the node where the switch is located downstream of the fault section, search for load nodes and tie switches in each branch downstream of the fault section; Step 5: The intelligent terminal units STU of the tie switch nodes that can be used to restore the non-fault power outage section communicate with each other, obtain the load information table information to be restored, compare the available remaining capacity of each tie switch node, and select the tie switch with the largest available remaining capacity as the tie switch for restoring power supply; Step 6: If the remaining capacity of the tie switch is greater than the total load to be restored, close the tie switch to restore power supply to all loads in the non-fault power outage section; otherwise, go to step 7; Step 7: Starting from the intelligent terminal unit STU of the contact switch node determined in step 5, search for adjacent nodes to which power supply can be restored one by one, and restore their power supply.

2. A distributed feeder fault handling and load recovery method for a multi-segment ring network according to claim 1, characterized in that: In step 1, the specific method for forming the upstream and downstream relationship information table is as follows: when the intelligent terminal unit STU is put into operation, the upstream and downstream relationship information table is filled in the intelligent terminal unit STU of each node according to the electrical connection relationship of the distribution network, so as to form the initial upstream and downstream relationship information table of the intelligent terminal unit STU of each node; during the operation of the distribution network, the opening and closing status of each switch is searched in real time and regularly from the intelligent terminal unit STU of the power supply node to each branch and to the intelligent terminal unit STU of the downstream node one by one, and the upstream and downstream relationship information table of the intelligent terminal unit STU of each node is modified according to the real-time changes.

3. A distributed feeder fault handling and load recovery method for a multi-segment ring network according to claim 1, characterized in that: In step 4, the specific search method is: Search the upstream and downstream relationship information table of the intelligent terminal unit STU node of the node where the downstream switch of the fault section is located for all the intelligent terminal unit STUs of the nodes connected to it except the intelligent terminal unit STU of the upstream node of the fault section, and the intelligent terminal unit STU of the node sends a search command to the intelligent terminal unit STUs of all the nodes connected to it except the intelligent terminal unit STU of the upstream node of the fault section. The intelligent terminal unit STU that receives the search command also sends a search command to the intelligent terminal unit STUs of all the nodes connected to it except the intelligent terminal unit STU of the upstream node of the fault section, and searches the intelligent terminal unit STUs of all the nodes downstream of the fault section one by one until all the contact switch nodes and the terminal load nodes are reached. Each searched load node and contact switch node is marked as a node downstream of the fault section, and each searched contact switch is marked as a contact switch that can be used to restore the non-fault power outage section. In the process of searching, a load information table to be restored is gradually formed, and the intelligent terminal unit STU name and load size of each load node to be restored are recorded in turn, and the final record table is sent to the intelligent terminal unit STU of the contact switch node connected to the terminal load node.

4. A distributed feeder fault handling and load recovery method for a multi-segment ring network according to claim 1, characterized in that: In step 7, the specific search method is: for any interconnecting switch that can restore power supply in the load information table to be restored, the intelligent terminal unit STU of the interconnecting switch node sends the available remaining capacity to the adjacent upstream node, and the adjacent upstream node calculates whether the available remaining capacity is less than the load required to restore the node, and records the interconnecting switch node name, the node name searched in sequence, the node load, the dynamic value of the available remaining capacity and whether the node branch line is traversed, and the record content forms a dynamic record table of the interconnecting switch node that can restore the load node. If the available remaining capacity is not less than the load required to restore the node, then after deducting the load of the node, the interconnecting switch node dynamic record table of the load node that can be restored is sent to other adjacent nodes of the node, and the adjacent nodes continue to calculate whether the available remaining capacity after deducting the load of the previous node is less than the load required to restore the node. Repeat the above process until all nodes in the load information table to be restored have been searched, or the available remaining capacity is less than the load required to restore the node. During the search process, the interconnecting switch node is continuously updated. Load node dynamic record table, and pass the record table to the intelligent terminal unit STU of the newly searched node, until a node is searched, the available remaining capacity is less than the load required to restore the node, then the interconnection switch node can restore the load node dynamic record table. A row of records of the node information is added to the end, and the record table information is sent to the intelligent terminal unit STU of the interconnection switch node. The intelligent terminal unit STU closes the switch according to the downstream switch name in the first row of the record table, and notifies the intelligent terminal unit STU of the node where the corresponding switch is located according to the downstream switch name on the branch in the last row of the record table, opens the downstream switch on the branch, and the node load cannot be restored by this interconnection switch. According to each row of nodes other than the last row in the record table, a load recovery message is sent to the intelligent terminal unit STU of each row of nodes, and the intelligent terminal unit STU of each node records the message. According to the node in the last row of the record table, a load non-recovery message is sent to the intelligent terminal unit STU of the node, and the intelligent terminal unit STU of the node records the load non-recovery message.

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