A Distributed Feeder Fault Handling and Load Restoration Method for a Multi-Segmented Ring Network

Abstract

The present invention provides a distributed feeder fault handling and load restoration method for a multi-segmented ring network, which relates to the technical field of distribution network feeder automation. It is used to achieve rapid fault location and isolation, and restore the load in the order of the electrical distances from the load nodes in the downstream area of the fault to the tie switch node from near to far. At the 10kV outgoing line switch of the substation and the intelligent terminal unit STU of each ring network, the intelligent terminal unit STU is internally provided with an overcurrent detection element, which real-time detects the current information flowing through each switch and the opening and closing state of the switch. At the same time, it realizes information exchange with adjacent intelligent terminal units STU through an optical fiber peer-to-peer communication network. Each intelligent terminal unit STU cooperates and communicates with each other, judges the fault location through information aggregation and fault criteria, issues commands to disconnect the switches at both ends of the fault to isolate the fault, and restores each load one by one in the order of the electrical distance close to the tie switch node, clarifies the steps and order of load restoration, can ensure the maximum degree of restoring the load near the tie switch, and has the characteristic of low feeder line loss.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network feeder automation, and specifically provides a distributed feeder fault handling and load restoration method for a multi-section ring network applicable to a multi-section multi-loop ring network. Background Art

[0002] With the increase in urban power supply load and the improvement of power supply reliability requirements, in order to improve the line utilization rate, on the basis of the conventional double-power single-loop network wiring method, a third or fourth power source is added to form a multi-power source wiring. Due to the variable actual distribution network operation mode, compared with the traditional ring network structure, the multi-loop distribution network has more load transfer paths and a more flexible operation mode, with the advantages of high efficiency and good economy. With the increase in tie switches, the distribution network operation mode has become more complex. While providing multiple power supply restoration path options for the distribution network after fault isolation, it also brings the trouble of how to quickly find the optimal restoration path.

[0003] Currently, there are mainly two types of widely used feeder automation systems: one is the local feeder automation system that cooperates the substation reclosing with sectional switches, but it can only work during a fault, and the fault handling process is strictly carried out according to the pre-setting principle, resulting in a long fault handling time; 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 achieve rapid fault location and isolation in a multi-section multi-loop ring network distribution network, and restore the load in the order of the electrical distances from the load nodes in the fault downstream area to the tie switch nodes from near to far, and provides a distributed feeder fault handling and load restoration method for a multi-section ring network.

[0005] The technical solution adopted by the present invention to solve the above technical problem is: a distributed feeder fault handling and load restoration method for a multi-section ring network, which is applied to a distributed feeder automation system. The distributed feeder automation system includes 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 units STU are both configured with overcurrent detection elements for real-time detection of current information and switch opening and closing states. 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 the intelligent terminal units of each group of ring networks are respectively used as a node. The method includes the following steps:

[0006] Step 1: Form an upstream and downstream relationship information table for each node. The table format is shown in Table 1. The upstream and downstream relationship information table includes at least the name of this node, the address of this node, the name of the adjacent node, the address of the adjacent node, the upstream and downstream relationship between this node and the adjacent node, the name of the connection switch of this node, whether the connection switch of this node is closed, the name of the connection switch of the adjacent node, whether the connection switch of the adjacent node is closed, whether this node is a power supply node, whether this node is a tie switch node, and whether this node is an end load node. Here, Table 1 is the format template of the upstream and downstream relationship information table.

[0007] Table 1 Upstream and Downstream Relationship Information Table

[0008]

[0009] Step 2: Each node intelligent terminal unit regularly collects the current values of the upstream switches in all lines of the node where it is located. The line refers to the line between the connection switch connecting this node and the adjacent downstream node and the connection switch connecting the adjacent downstream node and this node. It is required that the intelligent terminal unit STU of the node where the downstream connection switch is located transmits the current value of the downstream connection switch to it, compares the current values of the upstream connection switch and the downstream connection switch of each line segment, and determines whether a fault occurs in this line segment according to the pre-determined short-circuit current criterion for each line.

[0010] Step 3: If a fault occurs, the intelligent terminal unit STU of the node where the upstream connection switch of the fault section is located disconnects the upstream connection switch and notifies the intelligent terminal unit STU of the node where the downstream connection switch is located to disconnect the downstream connection switch to cut off the fault.

[0011] Step 4: Start searching for load nodes and tie switches in each branch downstream of the fault section from the intelligent terminal unit STU of the node where the downstream connection switch of the fault section is located.

[0012] Step 5: The intelligent terminal units STU of each tie switch node that can be used to restore the non-fault power outage section communicate with each other, all obtain the information of the load information table to be restored, compare the available remaining capacity of each tie switch node, and select the tie switch with the larger available remaining capacity as the tie switch for power restoration.

[0013] 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.

[0014] Step 7: Start searching for adjacent nodes that can be restored power supply one by one from the intelligent terminal unit STU of the tie switch node determined in Step 5 and restore their power supply.

[0015] Further, in the step 1, the specific formation method of the upstream and downstream relationship information table is as follows: when the smart terminal unit STU is put into operation, according to the electrical connection relationship of the distribution network, fill in the upstream and downstream relationship information table in the smart terminal unit STU of each node to form the initial upstream and downstream relationship information table of the smart terminal unit STU of each node. During the operation of the distribution network, start from the smart terminal unit STU of the power supply node and search for the opening and closing conditions of each switch one by one to each downstream node's smart terminal unit STU in each branch in real time and regularly, and modify the upstream and downstream relationship information table of the smart terminal unit STU of each node according to the real-time change situation.

[0016] Further, in the step 4, the search method for searching for 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 as follows:

[0017] Search for all the smart terminal units STU of the nodes connected to the smart 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 the smart terminal unit STU node, except for the smart terminal unit STU of the upstream node of the fault section. The smart terminal unit STU of this node sends a search command to all the smart terminal units STU of the nodes connected to it, except for the smart terminal unit STU of the upstream node of the fault section. The received smart terminal unit STU also sends a search command to all the smart terminal units STU of the nodes connected to it, except for the smart terminal unit STU of the upstream node of the fault section, and search for all the smart terminal units STU of the nodes downstream of the fault section one by one until all the tie switch nodes and the end load nodes are reached. Each searched load node and tie switch node is marked as a node downstream of the fault section. Each of the above-searched tie switches is marked as a tie switch available for restoring the non-fault power outage section. During the search process, a table of loads to be restored is gradually formed, and the name of the smart terminal unit STU of each load node to be restored and the load size of this node before the fault are recorded in sequence. Here, Table 2 is the format template of the table of loads to be restored, and the table format is shown in Table 2:

[0018] Table 2 Table of Loads to be Restored

[0019]

[0020] And send the final record table to the smart terminal unit STU of the tie switch node connected to the end load node.

[0021] Further, in the step 7, the specific search method for the tie switch STU to start searching for adjacent nodes that can resume power supply one by one in the vicinity is as follows: For any tie switch that can resume 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. The adjacent upstream node calculates whether the available remaining capacity is less than the load required to restore this node, and records the tie switch node name, the node names sequentially searched, the node load, the dynamic value of the available remaining capacity, and whether the node branch line has been traversed. The recorded content forms a dynamic record table of the nodes that can resume load for the tie switch node. Here, Table 3 is the format template of the dynamic record table of the nodes that can resume load for the tie switch node, and the table format is shown in Table 3:

[0022] Table 3 Dynamic Record Table of Nodes that can Resume Load for Tie Switch Node

[0023]

[0024] If the available remaining capacity is not less than the load required to restore this node, after deducting the load of this node, continue to send the dynamic record table of the nodes that can resume load for the tie switch node to other adjacent nodes of this node. The adjacent node continues 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, 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 this node. During the search process, continuously update the dynamic record table of the nodes that can resume load for the tie switch node, and pass the record table to the intelligent terminal unit STU required for the newly searched node until a certain node is searched and the available remaining capacity is less than the load required to restore this node. Then, add a record of the information of this node to the end of the dynamic record table of the nodes that can resume load for the tie switch node, and send the record table information to the intelligent terminal unit STU of the tie 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 upstream and downstream switches of the branch in the last row of the record table, notify the intelligent terminal unit STU of the node where the corresponding switch is located to open the upstream and downstream switches of this branch, indicating that the load of this node cannot be restored by this tie switch. According to each row of nodes other than the last row in the record table, send a load restored message to the intelligent terminal unit STU of each row of nodes, and the intelligent terminal unit STU of each node records this message. According to the node in the last row of the record table, send a load not restored message to the intelligent terminal unit STU of this node, and the intelligent terminal unit STU of this node records the load not restored message.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] (1) The present invention adopts a passive distribution network distributed fault section location and isolation scheme based on peer - to - peer communication between intelligent terminal units STU. This scheme uses the comparison of currents at both ends of the line as the principle for fault section location, with high location accuracy and strong reliability, quick - acting performance, sensitivity, and selectivity.

[0027] (2) The present invention adopts a distribution network topology information recognition and storage scheme applicable to the distributed control mode. This scheme has relatively low requirements for data calculation and storage of STU, only needs to configure basic static network topology information for the intelligent terminal unit STU, and automatically completes topology recognition and update during operation to adapt to changes in the operation mode of the distribution network, reducing the manual workload.

[0028] (3) The method adopted by the present invention can quickly restore power supply to all loads in the upstream area of the fault.

[0029] (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 near to far from the tie switch. This strategy avoids the uncertainty of multiple tie switches restoring different load nodes in a complex distribution network structure, and also minimizes the calculation amount for determining the load nodes to be restored, ensuring that the loads with a short electrical distance from the tie switch can be quickly and preferentially restored, and maximizing the restoration of power supply to adjacent loads. Brief Description of the Drawings

[0030] Figure 1 is a flowchart of the fault handling and load restoration method of the present invention.

[0031] Figure 2 is a schematic diagram of a multi - section three - tie loop network of the distribution network in an embodiment of the present invention. Detailed Embodiment

[0032] The technical solution of the present invention will be described in detail below in conjunction with the drawings and embodiments.

[0033] A distributed feeder fault handling and load restoration method for a multi - section loop network according to the present invention is applied to a distributed feeder automation system. The distributed feeder automation system includes a 10kV outgoing switch of a substation, multiple groups of intelligent terminal units STU, and an optical fiber peer - to - peer communication network. The 10kV outgoing switch of the substation and the intelligent terminal units STU are both equipped with over - current detection elements for real - time detection of current information and switch opening and closing states. The optical fiber peer - to - peer communication network is used to exchange information with adjacent intelligent terminal units STU. The 10kV outgoing switch of the substation and the intelligent terminal units of each group of loop networks are respectively used as a node, as Figure 1 shown, the method includes the following steps:

[0034] Step 1: Form an upstream and downstream relationship information table for each node. The upstream and downstream relationship information table includes at least the name of this node, the address of this node, the name of the adjacent node, the address of the adjacent node, the upstream and downstream relationship between this node and the adjacent node, the name of the connection switch of this node, whether the connection switch of this node is closed, the name of the connection switch of the adjacent node, whether the connection switch of the adjacent node is closed, whether this node is a power source node, whether this node is a tie switch node, and whether this node is an end load node. During the operation of the distribution network, the local intelligent terminal unit STU automatically and real-time updates the upstream and downstream relationship information table of each node's intelligent terminal unit STU through regularly collected local node information and information collected through communication with adjacent intelligent terminal units STU, ensuring the timeliness and accuracy of the upstream and downstream relationship information table of each node's intelligent terminal unit STU.

[0035] Step 2: Each node's intelligent terminal unit regularly collects the current values of the upstream switches in all the lines of the node where it is located. The line refers to the line between the connection switch connecting this node and the adjacent downstream node and the connection switch connecting the adjacent downstream node and this node. And it is required that the intelligent terminal unit STU of the node where the downstream connection switch of the line is located transmits the current value of the downstream connection switch to it. Compare the current values of the upstream and downstream connection switches of each line segment, and determine whether a fault has occurred in this line segment according to the pre-determined short-circuit current criterion for each line.

[0036] The intelligent terminal units STU of adjacent nodes regularly communicate with each other to collect and compare the current values at both ends of the line, ensuring the timeliness and accuracy of the fault location judgment.

[0037] Step 3: If a fault occurs, the intelligent terminal unit STU of the node where the upstream connection switch of the fault section is located disconnects the upstream connection switch and notifies the intelligent terminal unit STU of the node where the downstream connection switch is located to disconnect the downstream connection switch, cutting off the fault.

[0038] The intelligent terminal units STU at both ends of the fault issue commands in a timely and accurate manner to disconnect the switches at both ends of the fault, ensuring that the upstream nodes of the fault always remain powered.

[0039] Step 4: Start searching for load nodes and tie switches in each branch downstream of the fault section from the intelligent terminal unit STU of the node where the downstream connection switch of the fault section is located.

[0040] Search section by section from the intelligent terminal unit STU of the downstream switch of the fault section according to the information of the intelligent terminal units STU of adjacent nodes in the upstream and downstream relationship information table of each node's intelligent terminal unit STU, ensuring the integrity and rapidity of the search.

[0041] Step 5: The intelligent terminal units STU of each tie switch node that can be used to restore the non-fault power outage section communicate with each other, all obtain the information of the load information table to be restored, compare the available remaining capacity of each tie switch node, and select the tie switch with the larger available remaining capacity as the tie switch for power restoration.

[0042] Adopting the strategy of selecting the tie switch with the largest available remaining capacity ensures the restoration of power supply to as many loads as possible to the greatest extent.

[0043] 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 the power supply to all loads in the non-fault power outage section; otherwise, go to Step 7.

[0044] Step 7: Starting from the intelligent terminal unit STU of the tie switch node determined in Step 5, search for adjacent nodes that can be restored power supply one by one in the vicinity and restore their power supply.

[0045] Restore the loads in the fault downstream area one by one in the order of the electrical distance from the tie switch from near to far. This strategy avoids the uncertainty of multiple tie switches restoring different load nodes in a complex distribution network structure, and also minimizes the computational workload of determining the load nodes to be restored. It can ensure the rapid and priority restoration of the loads with a short electrical distance from the tie switch and restore the power supply to the adjacent loads to the greatest extent.

[0046] Furthermore, in the above Step 1, the specific formation method of the upstream and downstream relationship information table is as follows: When the intelligent terminal unit STU is put into operation, according to the electrical connection relationship of the distribution network, fill in the upstream and downstream relationship information table in the intelligent terminal unit STU of each node 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, start from the intelligent terminal unit STU of the power supply node and search for the opening and closing conditions of each switch one by one to the downstream nodes of each branch in real time and regularly, and modify the upstream and downstream relationship information table of the intelligent terminal unit STU of each node according to the real-time change situation, ensuring the timeliness and accuracy of the upstream and downstream relationship information table of each node STU.

[0047] Furthermore, in the above Step 4, the search method for searching for 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 as follows:

[0048] Search for all the intelligent terminal unit STUs of the 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, excluding the intelligent terminal unit STU of the node upstream of the fault section. The intelligent terminal unit STU of this node sends a search command to all the intelligent terminal unit STUs of the nodes connected to the intelligent terminal unit STU of the node upstream of the fault section. The intelligent terminal unit STU that receives the search command also sends a search command to all the intelligent terminal unit STUs of the nodes connected to the intelligent terminal unit STU of the node upstream of the fault section, and searches for all the intelligent terminal unit STUs of the nodes downstream of the fault section one by one until all the tie switch nodes and the end load nodes are reached. Each searched load node and tie switch node is marked as a node downstream of the fault section. Each of the above-searched tie switches is marked as a tie switch available for restoring the non-fault power outage section. During the search process, a table of loads to be restored is gradually formed, recording the name of the intelligent terminal unit STU and the load size of each load node to be restored in sequence, and sending the final record table to the intelligent terminal unit STU of the tie switch node connected to the end load node. The formed table records the load size for subsequent restoration decision-making.

[0049] Further, in the step 7, the specific search method for the tie switch STU to start searching adjacent nodes that can be restored to power one by one in the vicinity is as follows: For any tie switch that can be restored to power 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. The adjacent upstream node calculates whether the available remaining capacity is less than the load required to restore this 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 has been traversed. The recorded content forms a dynamic record table of the load nodes that can be restored by the tie switch node. If the available remaining capacity is not less than the load required to restore this node, after deducting the load of this node, continue to send the dynamic record table of the load nodes that can be restored by the tie switch node to other adjacent nodes of this node. The adjacent node continues 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, and repeats 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 this node. During the search process, continuously update the dynamic record table of the load nodes that can be restored by the tie switch node, and pass the record table to the intelligent terminal unit STU of the newly searched node until a certain node is searched and the available remaining capacity is less than the load required to restore this node. Then, add a record of the information of this node to the end of the dynamic record table of the load nodes that can be restored by the tie switch node, and send the record table information to the intelligent terminal unit STU of the tie 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 upstream and downstream switches of the branch in the last row of the record table, notify the intelligent terminal unit STU of the node where the corresponding switch is located to open the upstream and downstream switches of this branch, indicating that the load of this node cannot be restored by this tie switch. According to each row of nodes other than the last row in the record table, send a load restored message to the intelligent terminal unit STU of each row of nodes, and the intelligent terminal unit STU of each node records this message. According to the node in the last row of the record table, send a load not restored message to the intelligent terminal unit STU of this node, and the intelligent terminal unit STU of this node records the load not restored message. The dynamic record table tracks the available capacity and traversal situation to ensure that the nearest load is restored first and overload is avoided.

[0050] As Figure 2 shown, the feeder network is a multi-segment three-tie loop 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 initial available margin of the tie switches in the embodiment is shown in Table 5:

[0051] Table 4 Embodiment Load Information Table

[0052]

[0053] Table 5 Available Remaining Quantity Table of the Initial State of the Connection Switch

[0054]

[0055] A distributed feeder fault handling and load restoration method for a multi-section loop network of the present invention includes the following processing steps:

[0056] Step 1: Form an upstream and downstream relationship information table for each node intelligent terminal unit STU. When the intelligent terminal unit STU is put into operation, according to the electrical connection relationship of the distribution network, fill in the upstream and downstream relationship information table of each node intelligent terminal unit STU in each node intelligent terminal unit STU as shown in Table 6 - Table 19 below. The upstream and downstream relationship information table of each node intelligent terminal unit STU is stored in the database of each node;

[0057] Table 6 Upstream and Downstream Relationship Information Table of Node 1

[0058]

[0059] Table 7 Upstream and Downstream Relationship Information Table of Node 2

[0060]

[0061] Table 8 Upstream and Downstream Relationship Information Table of Node 3

[0062]

[0063] Table 9 Upstream and Downstream Relationship Information Table of Node 4

[0064]

[0065] Table 10 Upstream and Downstream Relationship Information Table of Node 5

[0066]

[0067] Table 11 Upstream and Downstream Relationship Information Table of Node 6

[0068]

[0069] Table 12 Upstream and Downstream Relationship Information Table of Node 7

[0070]

[0071] Table 13 Upstream and Downstream Relationship Information Table of Node 8

[0072]

[0073] Table 14 Upstream and Downstream Relationship Information Table of Node 9

[0074]

[0075] Table 15 Upstream and downstream relationship information table of Node 10

[0076]

[0077] Table 16 Upstream and downstream relationship information table of Node 11

[0078]

[0079] Table 17 Upstream and downstream relationship information table of Node 12

[0080]

[0081] Table 18 Upstream and downstream relationship information table of Node 13

[0082]

[0083] Table 19 Upstream and downstream relationship information table of Node 14

[0084]

[0085] Step 2:

[0086] The intelligent terminal unit STU7 collects the current value of the upstream connection switch K0708 in line 7 - 8 where it is located, and requests 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 significantly, it is determined that a fault has occurred in line 7 - 8. The method for determining whether a fault has occurred in the remaining lines is the same as the method for determining line 7 - 8 described above.

[0087] Step 3:

[0088] When a fault occurs in line 7 - 8, according to Step 2, the intelligent terminal unit STU7 determines that a fault has occurred in line 7 - 8. The intelligent terminal unit STU7 immediately disconnects K0708 and notifies the intelligent terminal unit STU8 to disconnect K0807 to cut off the fault.

[0089] Step 4:

[0090] A search command is issued from the intelligent terminal unit STU8 where the downstream switch K0807 of the faulty section is located to the intelligent terminal unit STU9 at the opposite node of the downstream branch. The intelligent terminal units STU8 and STU9 are marked as downstream nodes of the faulty 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 the tie switch available for restoring the non-faulty power outage section, and the intelligent terminal unit STU10 is marked as a downstream node of the faulty 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 faulty section and issues the search command to the intelligent terminal unit STU14. The intelligent terminal unit STU14 is marked as the tie switch available for restoring the non-faulty power outage section. During the search process, a table of load information to be restored in the embodiment is formed, as shown in Table 20:

[0091] Table 20 Table of Load Information to be Restored in the Embodiment

[0092]

[0093] And finally, the information in the table of load information to be restored is transmitted to the intelligent terminal unit STU14 at the node where the tie switch adjacent to the intelligent terminal unit STU11 of the end load node is located.

[0094] Step 5:

[0095] The intelligent terminal units STU14 and STU12 at the tie switch nodes available for restoring the non-faulty power outage section communicate with each other. The intelligent terminal units STU14 and STU12 at the tie switch nodes are compared, and the No. 12 tie switch with a larger available remaining capacity is selected as the tie switch for power restoration.

[0096] Step 6:

[0097] By comparing the remaining capacity of the No. 12 tie switch with the total load in the table of load information 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 table of load information to be restored.

[0098] Step 7:

[0099] 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 un-searched nodes 8, 10, and 11 until the remaining capacity of the end load node or the tie switch 12 cannot be used to restore this node, and a dynamic record table of the load that can be restored at the No. 12 tie switch node is formed as follows:

[0100] Table 21 Dynamic Record Table of Load Nodes that can be Restored at the No. 12 Tie Switch Node

[0101]

[0102] According to the dynamic record table of the load nodes that can be restored based on the 12th connection switch node, the intelligent terminal unit STU12 closes the switch K1209 and sends a command to the intelligent terminal unit STU11 to disconnect the switch K1110, restoring the power supply to nodes 8, 9, and 10.

[0103] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be modified or equivalently replaced, and any modification or partial replacement without departing from the spirit and scope of the present invention shall be covered by 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, the adjacent nodes whose power supply can be restored are searched one by one nearby, and their power supply is restored; 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.

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.

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