Distribution network primary and secondary fusion complete ring main unit line protection method and device

Abstract

The invention discloses a distribution network primary and secondary fusion complete ring main unit line protection method and device. The method comprises the following steps: determining a line between any two adjacent distribution network primary and secondary fusion complete ring main units as a to-be-protected line; any one of the two adjacent distribution network primary and secondary fusion complete ring main units is determined as the local side, and the other one is determined as the opposite side; if the power distribution terminal of the spacing unit at the side triggers a node fault signal after detecting a fault and receives an action permission signal sent by the power distribution terminal of the spacing unit at the opposite side, a command is sent to control the outlet at the side to trip, and fault removal is completed; and the power distribution terminal of the opposite-side interval unit sends an action allowing signal, and sends a command to control an opposite-side outlet to trip after receiving a node fault signal sent by the side so as to complete fault isolation. According to the scheme, the fault part can be cut off in time under the condition that the 10-kilovolt primary and secondary fusion complete ring main unit line breaks down, fault diffusion and upgrading are avoided, and stable operation of a 10-kilovolt distribution network system is protected.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated primary and secondary distribution network ring main units, and particularly to a line protection method and device for an integrated primary and secondary distribution network ring main unit. Background Art

[0002] Distribution automation is an important part of power system automation. It uses modern communication technology and computer technology to monitor, manage, and control the distribution network in real time. However, its functions are relatively single, mainly focusing on fault handling and power restoration. Although significant progress has been made in distribution automation in recent years, there are still some problems and challenges in actual operation. Problems such as single functions, insufficient information sharing, and poor system compatibility still need to be solved.

[0003] Patent CN201820365755.5 proposed a line protection and control device for a distribution network. This patent elaborated on the device structure and data interaction process, but did not conduct relevant research on the rules and logic of line protection itself. Patent CN202310957976.7 proposed an artificial intelligence algorithm that protects relevant data accumulated previously through offline training of the model to improve the accuracy and reliability of model judgment. It only conducts correlation analysis and precipitates experience on the waveforms and actions during a fault, and does not conduct relevant research on information interaction and judgment between devices. Patent CN201610807705.3 proposed a distributed line protection for a distribution network, which only described the protection method under a specific line loop closing state and did not conduct research on line protection based on distributed feeder automation and 61850 communication under normal operating modes.

[0004] Based on this, there is still a large room for improvement in the line protection of integrated primary and secondary distribution network ring main units in the prior art. Summary of the Invention

[0005] To solve the technical problem that the line of the integrated primary and secondary distribution network ring main unit fails to be cut off in time when a fault occurs, an embodiment of the present invention provides a line protection method and device for an integrated primary and secondary distribution network ring main unit.

[0006] The technical solution of the embodiment of the present invention is realized as follows:

[0007] An embodiment of the present invention provides a line protection method for a primary-secondary integrated complete loop network cabinet in a distribution network. The method includes: determining the line between any two adjacent primary-secondary integrated complete loop network cabinets in the distribution network as the line to be protected; determining any one of the two adjacent primary-secondary integrated complete loop network cabinets as the local side, and the other as the opposite side; the primary-secondary integrated complete loop network cabinet includes a power supply side incoming breaker, a plurality of feeder breakers, a loop network cabinet bus, and a plurality of distribution terminals; the incoming current of the primary-secondary integrated complete loop network cabinet flows into the loop network cabinet bus through the power supply side incoming breaker, and then flows into the plurality of feeder breakers from the loop network cabinet bus and then flows out; each breaker is respectively connected to a distribution terminal, and each distribution terminal is used for data acquisition and control of the connected breaker; each breaker and the corresponding connected distribution terminal form an interval unit, and the distribution terminals can communicate with each other; if the distribution terminal of the local side interval unit detects a fault and triggers a node fault signal, and after receiving the action permission signal sent by the distribution terminal of the opposite side interval unit, issues a command to control the local side outlet trip to complete fault removal; the distribution terminal of the opposite side interval unit sends an action permission signal, and after receiving the node fault signal sent by the local side, issues a command to control the opposite side outlet trip to complete fault isolation.

[0008] In one embodiment, the distribution terminal of the opposite side interval unit sending an action permission signal includes: the distribution terminal of the opposite side interval unit does not detect CT disconnection, and after receiving node fault or low voltage start-up blocked by PT disconnection, current sudden change start-up or zero-sequence voltage start-up, and no fault is detected after a preset time delay, issues an "action permission" signal;

[0009] The CT disconnection includes:

[0010] The distribution terminal of the interval unit judges whether the preset CT disconnection protection condition is satisfied; in the case of judging that the preset CT disconnection protection condition is satisfied, triggers a CT disconnection alarm after a preset third time delay and issues a device alarm signal;

[0011] The preset CT disconnection protection condition is:

[0012] The maximum phase current is greater than 0.02In; and the maximum phase current is greater than 4 times that of any one phase current.

[0013] In one embodiment, the low voltage start-up is that when any one of the three-phase voltages is lower than the low voltage setting value without PT disconnection, the distribution terminal of the interval switch starts a signal; the low voltage setting value is 30% of the rated phase voltage;

[0014] The current sudden change start-up is that when the sudden change of any one phase current is continuously greater than the sudden change start-up setting value three times, the distribution terminal of the interval switch starts a signal;

[0015] The calculation formula is as follows:

[0016] ||i(t) - i(t - T)| - |i(t - T) - i(t - 2T)|| ≥ I QD

[0017] where T is the sampling period, I QD is the starting setting value of the mutation quantity, i(t) is the current at time t, i(t - T) is the current at time t minus one sampling period; i(t - 2T) is the current at time t minus two sampling periods;

[0018] The zero-sequence voltage startup is that when the collected zero-sequence voltage exceeds the zero-sequence voltage setting value, the distribution terminal of the disconnector switch starts the signal.

[0019] In an embodiment, if the circuit breaker of the local interval unit is the last switch, and the last switch is the switch of the outermost overhead line configured with the distributed feeder automation function in the single-radiation power supply grid of the distribution network; then the distribution terminal connected to the last switch trips when it does not detect the fault trigger action permission signal and receives the node fault signal of the opposite-side distribution terminal; trips and triggers the node fault signal when detecting a fault;

[0020] If the circuit breaker of the local interval unit is the first switch, and the first switch is the first switch connected to the substation outgoing line switch in the distribution network configured with the distributed feeder automation function; then after the loss-of-voltage protection function of this first switch is put into operation, if there is no voltage and no current at the node of this line, the switch of this node is tripped after the set loss-of-voltage tripping time limit of the first switch;

[0021] If the circuit breaker of the local interval unit is the feeder switch, and the feeder switch is the outgoing line switch of the ring network cabinet in the distribution network; then when the distribution terminal of this feeder switch detects a fault, it trips and triggers the node fault signal; trips when receiving the bus tripping command and the switch is in the closed position.

[0022] In an embodiment, when the GOOSE communication of the distribution terminal of the interval unit is abnormal, the CT disconnection locks the bus protection.

[0023] In an embodiment, when the positive-sequence voltage of the bus is less than 30V and there is current in the line or the negative-sequence voltage is greater than 8V, the PT disconnection alarm signal is sent after a first preset duration; and after the bus voltage returns to normal, the PT disconnection alarm signal returns after a second preset duration of broadening.

[0024] In one embodiment, when the distribution terminal receives the signal of successful isolation and single-sided voltage loss, it controls the closing of the tie switch after a delay confirmation time; when the load prediction function is enabled, it controls the closing of the tie switch after receiving the transfer permission within the delay time to complete the power supply restoration; the load prediction function refreshes the load of each node on the line every first time period. After successful isolation downstream of the fault area, it sends out the signal of successful isolation and the required transferred load. The transferred load is forwarded to the distribution terminals on both sides along with the signal of successful isolation. After the first switch of the non-faulty line receives the signal of successful isolation, it calculates the remaining load of the line based on the current configured capacity and the real-time load. When the remaining load is greater than the transferred load, it sends out the transfer permission signal.

[0025] In one embodiment, the distribution terminal executes the power supply restoration function under the charging condition; it does not execute the power supply restoration function under the discharging condition;

[0026] The charging condition is that it meets the preset first condition and has a second delay time;

[0027] The preset first condition is:

[0028] The sectionalizing switch of this node is in the off position; there is voltage on any adjacent sectionalizing switch on this side and the opposite side; and there is no discharging condition;

[0029] The discharging condition is instantaneous discharging when any of the following preset second conditions is met;

[0030] The preset second conditions are:

[0031] The distributed FA function is disabled;

[0032] There is no voltage on the adjacent sectionalizing switches on this side and the opposite side for a certain period of time;

[0033] The "node fault" GOOSE input from the adjacent side;

[0034] The "node refusal to trip" GOOSE input from the adjacent side;

[0035] The isolating switch is in the off position;

[0036] The grounding switch is in the on position;

[0037] The power supply restoration action.

[0038] An embodiment of the present invention provides a line protection device for a primary-secondary integrated complete ring main unit in a distribution network. The device includes a plurality of primary-secondary integrated complete ring main units in the distribution network, and the line between any two adjacent primary-secondary integrated complete ring main units is a line to be protected; any one of the two adjacent primary-secondary integrated complete ring main units is determined as the local side, and the other is the opposite side; the primary-secondary integrated complete ring main unit includes a power supply side incoming line circuit breaker, a plurality of feeder circuit breakers, a ring main unit busbar, and a plurality of distribution terminals; the incoming current of the primary-secondary integrated complete ring main unit flows into the ring main unit busbar through the power supply side incoming line circuit breaker, and then flows from the ring main unit busbar into the plurality of feeder circuit breakers and then out; each circuit breaker is respectively connected to a distribution terminal, and each distribution terminal is used for data acquisition and control of the connected circuit breaker; each circuit breaker and the corresponding connected distribution terminal form an interval unit, and the distribution terminals can communicate with each other; the distribution terminal of the local interval unit is used for triggering a node fault signal after detecting a fault, and after receiving an action permission signal sent by the distribution terminal of the opposite interval unit, sending a command to control the local side to trip out, and completing fault removal; the distribution terminal of the opposite interval unit is used for sending an action permission signal, and after receiving the node fault signal sent by the local side, sending a command to control the opposite side to trip out and complete fault isolation.

[0039] In one embodiment, the distribution terminal includes:

[0040] The monitoring subsystem is used for real-time monitoring of the feeder status;

[0041] The fault detection subsystem is used for real-time identifying the interval unit fault and giving an alarm by analyzing the monitoring data;

[0042] The fault isolation subsystem is used for isolating the fault by tripping the interval switch after locating the fault position, so as to reduce the influence range of the fault;

[0043] The power supply restoration subsystem is used for starting the power supply restoration operation after isolating the fault, controlling the switches of relevant intervals to close, and restoring the power supply of the non-fault section.

[0044] The solution of this embodiment has the following beneficial effects:

[0045] (1) Data transmission efficiency and reliability. Distributed feeder automation directly maps the real-time data message coding to the data link layer, avoiding the complex processing of the network layer and the transport layer, thereby improving the reliability of data transmission and reducing the transmission delay.

[0046] (2) Avoid blind operation of equipment. From the perspective of traditional current quick-break protectors configured only at the feeder outlet, there may be a risk of blind operation of equipment, resulting in the entire feeder being cut off, which also affects non-faulty sections. This protection can achieve precise operation.

[0047] (3) Efficiency and accuracy. Compared with distributed feeder automation, traditional feeder automation may be less efficient and accurate in fault handling because it relies more on manual operation and empirical judgment and is easily interfered by subjective factors. This protection has high efficiency and accurate identification through real-time data monitoring and analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic flow chart of the line protection method for the integrated primary and secondary distribution network ring main unit in the embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the primary wiring of the integrated primary and secondary distribution network ring main unit in the embodiment of the present invention;

[0050] Figure 3 It is a schematic diagram of the primary wiring of the 10kV line in the embodiment of the present invention;

[0051] Figure 4 It is a schematic diagram of the physical object of the integrated primary and secondary distribution network ring main unit in the embodiment of the present invention;

[0052] Figure 5 It is a schematic diagram of the fault handling logic of the sectional switch in the embodiment of the present invention;

[0053] Figure 6 It is a schematic diagram of the non-fault recovery logic of the tie switch in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] The present invention will be further described in detail below with reference to the drawings and embodiments.

[0055] The embodiment of the present invention provides a line protection method for an integrated primary and secondary distribution network ring main unit, as Figure 1 shown, the method includes:

[0056] Step 101: Determine the line between any two adjacent primary-secondary integrated complete ring main units of the distribution network as the line to be protected; determine any one of the two adjacent primary-secondary integrated complete ring main units of the distribution network as the local side, and the other as the opposite side; the primary-secondary integrated complete ring main unit includes a power supply side incoming breaker, multiple feeder breakers, a ring main unit bus, and multiple distribution terminals; the incoming current of the primary-secondary integrated complete ring main unit flows into the ring main unit bus through the power supply side incoming breaker, and then flows from the ring main unit bus into the multiple feeder breakers and then out; each breaker is respectively connected to a distribution terminal, and each distribution terminal is used for data acquisition and control of the connected breaker; each breaker and the corresponding connected distribution terminal form an interval unit, and the distribution terminals can communicate with each other;

[0057] Step 102: If the distribution terminal of the local side interval unit detects a fault and triggers a node fault signal, and after receiving the action permission signal sent by the distribution terminal of the opposite side interval unit, issue a command to control the local side outlet to trip and complete the fault removal;

[0058] Step 103: The distribution terminal of the opposite side interval unit sends an action permission signal, and after receiving the node fault signal sent by the local side, issues a command to control the opposite side outlet to trip and complete the fault isolation.

[0059] This embodiment mainly cuts off the faulty part in time when a fault occurs in the 10 kV primary-secondary integrated complete ring main unit line, avoids the spread and escalation of the fault, and protects the stable operation of the 10 kV distribution network system.

[0060] The primary-secondary integrated complete ring main unit is a set of equipment in a power distribution system, mainly composed of an incoming line cabinet, an outgoing line cabinet, and corresponding protection and measurement and control devices. The primary-secondary integrated complete ring main unit integrates the primary and secondary distribution, protection, and control devices in one box. See Figure 2 、 Figure 3 and Figure 4, in the ring main unit, 301, 303, 305, 307, 309, and 311 are sectionalizing circuit breakers, where 301 is the incoming line circuit breaker on the power supply side, and 303, 305, 307, 309, and 311 are feeder circuit breakers. The copper bars connecting the above circuit breakers are the busbars of the ring main unit. Current flows into the ring main unit through 301 and flows through the busbars to the feeder circuit breakers 303, 305, 307, 309, and 311 until it reaches the downstream user load. Different from traditional ring main units, each interval loop of the integrated primary and secondary ring main unit is equipped with a distribution terminal (protection and measurement control device). The distribution terminal can realize real-time acquisition and monitoring of data such as voltage, current, and switch information of this loop. When a fault such as a short circuit occurs, the circuit breaker can be selectively, quickly, reliably, and sensitively isolated from the fault through the secondary protection device of this loop. The device can not only realize the line protection function of this interval unit but also, based on the mutual communication of each distribution terminal, realize the distributed feeder automation function.

[0061] The specific action logic of the solution in this embodiment is as follows:

[0062] Figure 2 Shown is the primary main wiring diagram of the integrated primary and secondary ring main unit. As Figure 3 shown, the line protection range is from the 303 switch of this ring main unit to the 301 switch of the downstream ring main unit on the same line. Therefore, the switch on this side refers to Figure 2 the interval 303 shown, and the switch on the opposite side refers to the 301 switch of the downstream ring main unit connected to this ring main unit.

[0063] See Figure 5 , and the line protection logic includes the following:

[0064] Fault removal: After the distribution terminal (protection and measurement control device) of the switch in this interval detects a fault, it triggers the "node fault" signal. At the same time, after receiving the "action permission" signal confirmation from the distribution terminal (protection and measurement control device) of the switch in the opposite interval, it trips out.

[0065] Fault isolation: The distribution terminal (protection and measurement control device) of the switch in this interval triggers the "action permission" signal. At the same time, after receiving the "node fault" signal from the distribution terminal (protection and measurement control device) of the switch in the opposite interval, it issues a command to trip out and open the switch in this interval.

[0066] CT disconnection of any switch on both sides of the line locks the line protection. When the GOOSE communication of the distribution terminal (protection and measurement control device) of each interval is abnormal, the corresponding line protection is locked.

[0067] "Operation Permitted" signal: The signal that permits the operation of the switch upstream of the fault area. The distribution terminal (protection and measurement control device) of the switch in this switch bay does not detect CT disconnection. The distribution terminal (protection and measurement control device) of the bay switch receives "Node Fault" or low-voltage start-up, sudden change in current start-up, or zero-sequence voltage start-up blocked by PT disconnection. If no fault is detected after a 20-ms delay, the "Operation Permitted" signal is output.

[0068] Low-voltage start-up: In the case of no PT disconnection, when the amplitude of any one of the three-phase voltages is lower than the low-voltage setting value, the distribution terminal (protection and measurement control device) of the bay switch starts the signal. The low-voltage setting value is defaulted to 30% of the rated phase voltage.

[0069] Sudden change in current start-up:

[0070] ||i(t)-i(t-T)|-|i(t-T)-i(t-2T)||≥I QD

[0071] where: T — sampling period, I QD — sudden change in current start-up setting value; i(t) is the current at time t, i(t-T) is the current at time t minus one sampling period; i(t-2T) is the current at time t minus two sampling periods.

[0072] When the sudden change in current of any one phase is greater than the start-up threshold for three consecutive times, the distribution terminal (protection and measurement control device) of the bay switch starts the signal.

[0073] Zero-sequence voltage start-up: When the collected zero-sequence voltage exceeds the zero-sequence voltage setting value, the distribution terminal (protection and measurement control device) of the bay switch starts the signal.

[0074] Protection setting value: The protection setting value is a protection measure for specific numerical values or set values. In some systems or devices, in order to protect their normal operation and stability, some specific numerical values or set values may be set. The purpose of the protection setting value is to ensure that the system does not exceed or cross these set numerical ranges during operation to prevent system failures, equipment damage, or other adverse consequences.

[0075] Fault handling logic for the last switch (the switch of the outermost overhead line with distributed feeder automation function in the single-radiation power supply network of the distribution network): After meeting the start-up conditions, if the distribution terminal (protection and measurement control device) does not detect a fault and triggers the "Operation Permitted" signal, and at the same time receives the "Node Fault" signal from the opposite-side distribution terminal (protection and measurement control device), it trips out. After detecting a fault, the distribution terminal (protection and measurement control device) trips out through the conventional protection and triggers the "Node Fault" signal.

[0076] Fault handling logic for the first switch (the first switch connected to the substation outgoing switch in a distribution network configured with distributed feeder automation function): After the under-voltage protection of the first switch is enabled, if there is no voltage and no current at the nodes of this line, the distribution terminal (protection and measurement device) will trip the switch at this node after the set time limit for under-voltage tripping of the first switch.

[0077] Fault handling logic for the feeder switch (the outgoing switch of the ring main unit in the cable line of the distribution network): After the conventional protection trips and exports after the distribution terminal (protection and measurement device) in this interval detects a fault, it triggers the "node fault" signal. When receiving the "bus trip command" and the switch is in the closed position and has not tripped, it should be immediately tripped.

[0078] PT disconnection logic: When the positive-sequence voltage of the bus is less than 30V and there is current in the line or the negative-sequence voltage is greater than 8V, a "PT disconnection alarm" signal is sent after a delay of 10s. When the bus voltage returns to normal, after a 1.25s delay extension, the "PT disconnection alarm" returns.

[0079] CT disconnection logic:

[0080] 1. The maximum phase current is greater than 0.02In;

[0081] 2. The maximum phase current is greater than 4 times that of any other phase current.

[0082] When the above two conditions are met, a "CT disconnection alarm" is reported after a delay of 10 seconds, and the device alarm signal is sent.

[0083] See Figure 6 , and the restoration logic includes:

[0084] For the sectionalizing switch (in a medium-voltage distribution network with a network structure of closed-loop design and open-loop operation, used to isolate multi-terminal power supply sources, the sectionalizing switch or tie switch that is normally in the open position), after the distribution terminal (protection and measurement device) in the interval receives the signal of successful isolation and unilateral under-voltage, it controls the sectionalizing switch to close after the delay confirmation time. When the load prediction function is enabled, it is necessary to receive the transfer permission at the same time within the delay time to control the sectionalizing switch to close.

[0085] Load prediction: Each node on the line refreshes its own load every 30s. After successful isolation downstream of the fault area, it sends the signal of successful isolation and the required transferred load. The transferred load is forwarded to the distribution terminals (protection and measurement devices) on both sides along with the successful isolation signal. After the first switch of the non-faulty line receives the successful isolation signal, it calculates the remaining load of the line based on the current configured capacity and the real-time load. When the remaining load is greater than the transferred load, a transfer permission signal is sent.

[0086] Power supply restoration charging and discharging conditions:

[0087] a) Charging conditions:

[0088] 1) The sectionalizing switch of this node is in the off position;

[0089] 2) There is voltage on any adjacent sectionalizing switch on this side and the opposite side;

[0090] 3) There are no discharge conditions.

[0091] (After the above conditions are all met, it will turn to the charging state after a certain delay (default is 15s), and it is determined that the sectionalizing switch of this interval is the open-loop point.)

[0092] b) Discharge conditions:

[0093] 1) The distributed FA function is exited;

[0094] 2) There is no voltage on the adjacent sectionalizing switches on this side and the opposite side for a certain delay (default is 15s);

[0095] 3) The "node fault" GOOSE input from the adjacent side;

[0096] 4) The "node refuses to trip" GOOSE input from the adjacent side;

[0097] 5) The isolating switch is in the off position;

[0098] 6) The earthing switch is in the on position;

[0099] 5) The power supply restoration action.

[0100] (When any of the above conditions is met, the power supply restoration will instantaneously discharge.)

[0101] To determine whether there is voltage on the opposite side, the PT acquisition method or subscribing to the GOOSE signal of the opposite node having voltage can be used.

[0102] Malfunction judgment conditions: If the switch changes from closed to open and there is no current within the switch malfunction time, then trigger the "fault isolation successful" GOOSE output signal; if the switch of this node still fails to trip within the switch malfunction time, then trigger the "switch refuses to trip" GOOSE output signal. The time range should comply with Appendix C.

[0103] Distributed FA input / exit: If any of the distributed FA soft or hard pressure plates of the terminals is exited, the intelligent distributed FA for the whole line will be exited and the conventional protection will be enabled; if all the distributed FA soft and hard pressure plates of the terminals on the whole line are input, the intelligent distributed FA for the whole line will be input. The intelligent distributed input and exit for the whole line are controlled by the locking value and reset value output by the trunk line switch.

[0104] Requirements for tripping due to switch failure: When a switch fails to trip, the "switch refusal to operate" GOOSE signal should be triggered. When the sectionalizing switch node receives the "switch refusal to operate" GOOSE signal from the opposite side, and the switch at this node is in the closed position and has not tripped, it should immediately trip. After receiving the "switch refusal to operate" GOOSE signal from other nodes on the bus, the sectionalizing switch trips and issues the "bus tripping command". If the sectionalizing switch does not detect a fault and trips successfully, the "fault isolation successful" GOOSE signal should be triggered.

[0105] The solution of this embodiment has the following beneficial effects:

[0106] (1) Data transmission efficiency and reliability. Distributed feeder automation maps the real-time data message encoding directly to the data link layer, avoiding the complex processing of the network layer and the transport layer, thus improving the reliability of data transmission and reducing the transmission delay.

[0107] (2) Avoiding blind operation of equipment. Considering only the traditional current quick-break protector configured at the feeder outlet, there may be a risk of blind operation of the equipment, resulting in the entire feeder being cut off and affecting non-faulty sections. This protection can achieve precise operation.

[0108] (3) Efficiency and accuracy. Compared with distributed feeder automation, traditional feeder automation may be less efficient and accurate in fault handling because it relies more on manual operation and empirical judgment and is easily interfered by subjective factors. This protection has high efficiency and accurate identification through real-time data monitoring and analysis.

[0109] An embodiment of the present invention provides a line protection device for a primary-secondary integrated complete loop network cabinet in a distribution network. The device includes a plurality of primary-secondary integrated complete loop network cabinets in the distribution network. The line between any two adjacent primary-secondary integrated complete loop network cabinets is a line to be protected. Any one of the two adjacent primary-secondary integrated complete loop network cabinets is determined as the local side, and the other is the opposite side. The primary-secondary integrated complete loop network cabinet includes a power supply side incoming breaker, a plurality of feeder breakers, a loop network cabinet bus, and a plurality of distribution terminals. The incoming current of the primary-secondary integrated complete loop network cabinet flows into the loop network cabinet bus through the power supply side incoming breaker, and then flows into the plurality of feeder breakers from the loop network cabinet bus and then flows out. Each breaker is respectively connected to a distribution terminal, and each distribution terminal is used to collect data and control the connected breaker. Each breaker and the corresponding connected distribution terminal form an interval unit, and the distribution terminals can communicate with each other. The distribution terminal of the local side interval unit is used to trigger a node fault signal after detecting a fault, and after receiving an action permission signal sent by the distribution terminal of the opposite side interval unit, issue a command to control the local side outlet to trip and complete fault removal. The distribution terminal of the opposite side interval unit is used to send an action permission signal and, after receiving the node fault signal sent by the local side, issue a command to control the opposite side outlet to trip and complete fault isolation.

[0110] The method of this embodiment identifies changes and fault locations based on intelligent algorithms and line feeding characteristics, and realizes real-time monitoring and fault handling of various parameters of the power system. In this embodiment, the distribution terminal mainly consists of the following aspects:

[0111] Monitoring subsystem: Encapsulated and built into the distribution terminal (protection and measurement control device) of each interval unit, it is responsible for real-time monitoring of the feeder status, including the collection and transmission of parameters such as current and voltage. This helps to promptly detect abnormal conditions during the operation of the feeder.

[0112] Fault detection subsystem: Encapsulated and built into the distribution terminal (protection and measurement control device) of each interval unit, it deeply applies the data collected by the monitoring subsystem. By analyzing the monitoring data, it can identify interval unit (feeder) faults in real time and give an alarm. This technology can quickly and accurately detect and locate various faults in the power system, including overload, short circuit, grounding, etc.

[0113] Fault isolation subsystem: Encapsulated and built into the distribution terminal (protection and measurement control device) of each interval unit, it deeply applies the data collected by the monitoring subsystem. After locating the fault location, it isolates the fault by tripping the interval switch to reduce the fault influence range. This helps to control the fault influence within the smallest range and ensure the stable operation of the power system. It may only take dozens of milliseconds from the protection action to the successful fault isolation.

[0114] Power restoration subsystem: Encapsulated and built into the distribution terminals (protection and measurement control devices) of each interval unit, it deeply applies the data collected by the monitoring subsystem. After isolating the fault, it initiates the power restoration operation, controls the closing of the switches in the relevant intervals, and restores the power supply to the non-faulty sections. The power restoration process is also relatively rapid, and it may only take a few hundred milliseconds from successful fault isolation to power restoration. Line protection based on distributed feeder automation can be widely applied to the automated management, intelligent upgrade, and optimized operation of power systems, especially having significant advantages in aspects such as fault detection and location, remote monitoring and management. Specific application scenarios include the status monitoring and fault handling of cable branches, utility poles, and equipment connected to substations, distribution rooms, box-type substations, etc.

[0115] The above device provided in this embodiment and the above method embodiment belong to the same concept. For the specific implementation process, please refer to the method embodiment and will not be elaborated here.

[0116] It should also be noted that the term "including", "comprising", or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, commodity, or device. Without further limitations, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity, or device including the element.

[0117] The above are only the embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for protecting the line of a distribution network primary and secondary integrated ring network box, characterized in that: The method comprises: Determine the line between any two adjacent primary and secondary integrated ring network boxes of the distribution network as the line to be protected; determine any one of the two adjacent primary and secondary integrated ring network boxes as the local side, and determine the other as the opposite side; the primary and secondary integrated ring network box of the distribution network includes a power supply side incoming line circuit breaker, multiple feeder circuit breakers, a ring network box bus and multiple distribution terminals; the inflow current of the primary and secondary integrated ring network box of the distribution network flows into the ring network box bus through the power supply side incoming line circuit breaker, and then flows into the multiple feeder circuit breakers from the ring network box bus before flowing out; each circuit breaker is respectively connected to a corresponding distribution terminal, and each distribution terminal is used to collect data and control the connected circuit breaker; each circuit breaker and the correspondingly connected distribution terminal form an interval unit, and the distribution terminals can communicate with each other; If the distribution terminal of the bay unit on this side detects a fault and triggers a node fault signal, and receives an action permission signal sent by the distribution terminal of the bay unit on the opposite side, it issues a command to control the outlet on this side to trip and complete the fault removal; The power distribution terminal of the opposite bay unit sends an action permission signal, and after receiving the node fault signal sent by this side, it issues a command to control the opposite outlet to trip and complete fault isolation.

2. The method for protecting the line of the primary and secondary integrated ring network box of the distribution network according to claim 1 is characterized in that: The power distribution terminal of the opposite bay unit sends an action permission signal, including: The power distribution terminal of the opposite bay unit does not detect CT disconnection, and receives a node fault or low voltage start, current sudden change start or zero sequence voltage start locked by PT disconnection. After the preset delay time, no fault is detected and an "action allowed" signal is issued; The CT disconnection includes: The power distribution terminal of the bay unit determines whether the preset CT disconnection protection condition is met; if it is determined that the preset CT disconnection protection condition is met, a preset third time length is delayed to trigger the CT disconnection alarm, and a device alarm signal is issued; The preset CT disconnection protection condition is: The maximum phase current is greater than 0.02In; and the maximum phase current is greater than 4 times the current of any phase.

3. The method for protecting the line of the primary and secondary integrated ring network box of the distribution network according to claim 2 is characterized in that: The low voltage start is a start signal of the power distribution terminal of the interval switch when the amplitude of any phase of the three-phase voltage is lower than the low voltage setting value in the case of no PT disconnection; the low voltage setting value is 30% of the rated phase voltage; The current sudden change start is a start signal of the distribution terminal of the interval switch when the current sudden change of any phase is greater than the sudden change start setting value for three consecutive times; The calculation formula is: ||i(t)-i(t-T)|-|i(t-T)-i(t-2T)||≥I QD Where T is the sampling period, I QD is the starting constant of the sudden change, i(t) is the current at time t, i(tT) is the current at time t minus one sampling cycle; i(t-2T) is the current at time t minus two sampling cycles; The zero-sequence voltage start-up is to collect the distribution terminal start-up signal of the interval switch when the zero-sequence voltage exceeds the zero-sequence voltage set value.

4. The method for protecting the line of the primary and secondary integrated ring network box of the distribution network according to claim 1 is characterized in that: If the circuit breaker of the interval unit on this side is the last switch, the last switch is the last overhead line switch configured with distributed feeder automation function in the single radial power supply grid of the distribution network; the distribution terminal connected to the last switch trips at the outlet when no fault triggering action permission signal is detected and a node fault signal of the opposite distribution terminal is received; when a fault is detected, the outlet trips and triggers a node fault signal; If the circuit breaker of the bay unit on this side is the primary switch, the primary switch is the first switch connected to the outgoing line switch of the substation in the distribution network configured with the distributed feeder automation function; then after the undervoltage protection function of the primary switch is put into operation, if there is no pressure and no current at the node of the line, the switch of this node will be tripped after the set undervoltage tripping time limit of the primary switch; If the circuit breaker of the interval unit on this side is a feeder switch, and the feeder switch is the outlet switch of the ring network box in the distribution network; then when the distribution terminal of this feeder switch detects a fault, the outlet trips and triggers a node fault signal; when the bus tripping command is received and the switch is in the closed position, the outlet trips.

5. The method for protecting the line of the primary and secondary integrated ring network box of the distribution network according to claim 1 is characterized in that: When the GOOSE communication of the power distribution terminal of the bay unit is abnormal, the CT disconnection and busbar protection are locked.

6. The method for protecting the line of the primary and secondary integrated ring network box of the distribution network according to claim 1 is characterized in that: When the bus positive sequence voltage is less than 30V and there is current in the line or the negative sequence voltage is greater than 8V, the distribution terminal of the interval unit sends a PT line break alarm signal after a delay of the first preset time; and after the bus voltage returns to normal, the PT line break alarm signal is returned after a second preset time extension.

7. The method for protecting the line of the primary and secondary integrated ring network box of the distribution network according to claim 1 is characterized in that: The power distribution terminal receives the signal of successful isolation and one-side voltage loss, and controls the contact switch to close after the delayed confirmation time; When the load prediction function is activated, the interconnection switch is controlled to close after receiving the power transfer permission within the delay time to complete the power supply restoration; The load prediction function is that each node of the line refreshes its own load every first period of time. After the downstream isolation of the fault area is successful, the isolation success and the required transfer load are issued. The transferred load is forwarded to the distribution terminals on both sides along with the isolation success signal. After the first switch of the non-fault line receives the isolation success signal, the remaining load of the line is calculated based on the current configuration capacity and real-time load. When the remaining load is greater than the transfer load, a transfer permission signal is issued.

8. The method for protecting the line of the primary and secondary integrated ring network box of the distribution network according to claim 7 is characterized in that: The power distribution terminal performs a power supply recovery function under charging conditions; and does not perform a power supply recovery function under discharging conditions; The charging condition is that the charging is delayed for a second time period when a preset first condition is met; The preset first condition is: The interval switch of this node is in the open position; and any adjacent interval switch on this side and the opposite side is pressurized; and there is no discharge condition; The discharge condition is instantaneous discharge under any of the following preset second conditions; The preset second condition is: Distributed FA function exits; There is no pressure delay for a certain period of time for the adjacent interval switches on this side and the opposite side; Adjacent side "node failure" GOOSE input; Adjacent side "node rejection" GOOSE input; The isolation switch is in the open position; The grounding switch is in the closed position; Power restoration action.

9. A distribution network primary and secondary integrated ring network box line protection device, characterized in that: The device comprises a plurality of distribution network primary and secondary integrated ring network boxes, and the line between any two adjacent distribution network primary and secondary integrated ring network boxes is a line to be protected; any one of the two adjacent distribution network primary and secondary integrated ring network boxes is determined as the local side, and the other is the opposite side; the distribution network primary and secondary integrated ring network box comprises a power supply side incoming line circuit breaker, a plurality of feeder circuit breakers, a ring network box bus and a plurality of distribution terminals; the inflow current of the distribution network primary and secondary integrated ring network box flows into the ring network box bus through the power supply side incoming line circuit breaker, and then flows into the plurality of feeder circuit breakers from the ring network box bus before flowing out; each circuit breaker is respectively connected to a corresponding distribution terminal, and each distribution terminal is used to collect data and control the connected circuit breaker; each circuit breaker and the correspondingly connected distribution terminal form an interval unit, and the distribution terminals can communicate with each other; The power distribution terminal of the bay unit on this side is used to trigger a node fault signal after detecting a fault, and after receiving an action permission signal sent by the power distribution terminal of the bay unit on the opposite side, issue a command to control the outlet on this side to trip and complete the fault removal; The power distribution terminal of the opposite side interval unit is used to send an action permission signal and issue a command to control the opposite side outlet to trip after receiving the node fault signal sent by this side to complete fault isolation.

10. The distribution network primary and secondary integrated ring network box line protection device according to claim 9 is characterized in that: The power distribution terminal comprises: The monitoring subsystem is used to monitor the feeder status in real time; The fault detection subsystem is used to identify the fault of the bay unit in real time and issue an alarm by analyzing the monitoring data; The fault isolation subsystem is used to locate the fault position and isolate the fault by tripping the interval switch to reduce the scope of the fault impact; The power supply restoration subsystem is used to start the power supply restoration operation after isolating the fault, control the closing of the switches in the relevant intervals, and restore the power supply to the non-fault sections.

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