A distribution network primary and secondary fusion complete ring network box line protection method and device

Abstract

The application discloses a kind of distribution network primary-secondary fusion complete set looped network box line protection method and device.Method includes determining the line between any two adjacent distribution network primary-secondary fusion complete set looped network box as to be protected line;Any one of the two adjacent distribution network primary-secondary fusion complete set looped network box is determined as this side, and the other is determined as opposite side;If the power distribution terminal of this side interval unit detects fault and triggers node fault signal, and receives the action permission signal sent by the power distribution terminal of opposite side interval unit, issue command control this side outlet trip, complete fault removal;The power distribution terminal of opposite side interval unit sends action permission signal, and receives the node fault signal sent by this side, issue command control opposite side outlet trip, complete fault isolation.The application scheme can cut off fault part in time under the condition that 10 kilovolt primary-secondary fusion complete set looped network box line appears fault, avoid fault diffusion and escalation, protect the stable operation of 10 kilovolt distribution network system.

Description

Technical Field

[0001] This invention relates to the field of integrated primary and secondary distribution network ring network boxes, and particularly to a method and device for line protection of integrated primary and secondary distribution network ring network boxes. Background Technology

[0002] Distribution automation is a crucial component of power system automation, utilizing modern communication and computer technologies for real-time monitoring, management, and control of the distribution network. However, its functionality is relatively limited, primarily focusing on fault handling and power restoration. Despite significant progress in distribution automation in recent years, several problems and challenges remain in practical operation. Issues such as limited functionality, insufficient information sharing, and poor system compatibility still need to be addressed.

[0003] Patent CN201820365755.5 proposes a distribution network line protection control device. This patent describes the device structure and data interaction process, but does not conduct research on the rule logic of line protection itself. Patent CN202310957976.7 proposes an artificial intelligence algorithm that uses offline training models to protect previously accumulated data, improving the accuracy and reliability of model judgments. It only performs correlation analysis and experience accumulation on waveforms and actions during fault occurrences, without researching information interaction and judgment between devices. Patent CN201610807705.3 proposes a distributed line protection method for distribution networks. It only describes the protection method under specific line loop states, without researching line protection based on distributed feeder automation and 61850 communication under conventional operating conditions.

[0004] Based on this, there is still considerable room for improvement in the existing technology regarding the line protection of integrated primary and secondary ring network boxes for distribution networks. Summary of the Invention

[0005] To address the technical problem of failure to promptly disconnect lines in integrated primary and secondary distribution network ring network boxes when faults occur, this invention provides a method and device for protecting the lines of integrated primary and secondary distribution network ring network boxes.

[0006] The technical solution of this invention is implemented as follows:

[0007] This invention provides a method for protecting a distribution network integrated primary and secondary ring main unit (PNU) line. The method includes: determining the line between any two adjacent PNU integrated PNU ring main units as the line to be protected; designating one of the two adjacent PNU integrated PNU ring main units as the local side and the other as the opposite side; the PNU integrated PNU ring main unit includes a power supply side incoming circuit breaker, multiple feeder circuit breakers, a ring main unit busbar, and multiple distribution terminals; the current flowing into the PNU integrated PNU ring main unit flows through the power supply side incoming circuit breaker into the ring main unit busbar, and then from the ring main unit busbar into the multiple feeder circuit breakers. Outflow; each circuit breaker is connected to a corresponding distribution terminal, and each distribution terminal is used to collect and control data from the connected circuit breaker; each circuit breaker and its corresponding distribution terminal form a bay unit, and the distribution terminals can communicate with each other; if the distribution terminal of this bay unit detects a fault and triggers a node fault signal, and receives an action permission signal from the distribution terminal of the opposite bay unit, it issues a command to control the tripping of the output circuit breaker on this side to complete the fault clearing; the distribution terminal of the opposite bay unit sends an action permission signal, and receives a node fault signal from this side, and issues a command to control the tripping of the output circuit breaker on the opposite side to complete the fault isolation.

[0008] In one embodiment, the power distribution terminal of the opposite side bay unit sends an operation permission signal, including: the power distribution terminal of the opposite side bay unit does not detect CT disconnection, and receives a node fault or low voltage start, current surge start or zero sequence voltage start blocked by PT disconnection, and after a preset delay, if no fault is detected, it issues an "operation permission" signal.

[0009] The CT line break includes:

[0010] The power distribution terminal of the bay unit determines whether the preset CT disconnection protection conditions are met; if the preset CT disconnection protection conditions are met, the CT disconnection alarm is triggered after a preset third time delay, and a device alarm signal is issued.

[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 any phase current.

[0013] In one embodiment, the low-voltage start is a distribution terminal start signal of the switchgear when the amplitude of any one of the three-phase voltages is lower than the low-voltage setting value in the absence of PT disconnection; the low-voltage setting value is 30% of the rated phase voltage.

[0014] The current surge trigger is a signal that activates the distribution terminal of the bay switch when the current surge of any phase exceeds the surge trigger value three times consecutively.

[0015] The calculation formula is:

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

[0017] Where T is the sampling period, I QD The setpoint is set for the sudden change, i(t) is the current at time t, i(tT) is the current at time t minus one sampling period, and i(t-2T) is the current at time t minus two sampling periods.

[0018] The zero-sequence voltage start-up is the start signal of the distribution terminal of the interval switch when the zero-sequence voltage exceeds the zero-sequence voltage set value.

[0019] In one embodiment, if the circuit breaker of the local bay unit is the last switch, and the last switch is the last overhead line switch in the single radial power supply network of the distribution network with distributed feeder automation function; then the distribution terminal connected to the unswitched unit will trip at the output if no fault triggering action permission signal is detected and a fault signal of the distribution terminal node on the other side is received; and the output will trip and trigger the node fault signal if a fault is detected.

[0020] If the circuit breaker of this side bay unit is the first switch, and the first switch is the first switch connected to the substation outgoing switch in a distribution network with distributed feeder automation function; then after the undervoltage protection function of this first switch is put into operation, if there is no voltage and no current at this line node, the switch of this node will trip after the set undervoltage tripping time limit of the first switch.

[0021] If the circuit breaker of this side bay unit is a feeder switch, and the feeder switch is an outgoing switch of the ring network box in the distribution network; then, if the distribution terminal of this feeder switch detects a fault, the output trips and triggers a node fault signal; if a bus trip command is received and the switch is in the closed position, the output trips.

[0022] In one embodiment, the CT disconnection blocking busbar protection is performed when the GOOSE communication of the distribution terminal of the bay unit is abnormal.

[0023] In one 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 power distribution terminal of the bay unit sends a PT disconnection alarm signal after a first preset time delay; and after the bus voltage returns to normal, the PT disconnection alarm signal is returned after a second preset time extension.

[0024] In one embodiment, the distribution terminal receives a signal indicating successful isolation and unilateral power loss, and controls the tie switch to close after a delay confirmation time. When the load prediction function is activated, it simultaneously receives a transfer permission signal within the delay time and controls the tie switch to close, thus completing the power supply restoration. The load prediction function refreshes the load of each node on the line every first time interval. After successful isolation downstream of the fault area, it sends a signal indicating successful isolation and the required transfer load. The transfer load is forwarded to the distribution terminals on both sides along with the successful isolation signal. After receiving the successful isolation signal, the first switch of the non-faulty line calculates the remaining load of the line based on the current configured capacity and real-time load. When the remaining load is greater than the transfer load, it sends a transfer permission signal.

[0025] In one embodiment, the power distribution terminal performs a power restoration function under charging conditions; it does not perform a power restoration function under discharging conditions.

[0026] The charging condition is that a preset first condition is met and a second time delay is applied.

[0027] The preset first condition is:

[0028] The interval switch at this node is in the open position; and both the interval switches on this side and the opposite side are under voltage; and there is no condition for discharge.

[0029] The discharge condition is instantaneous discharge under any of the following preset second conditions;

[0030] The preset second condition is:

[0031] Distributed FA function exited;

[0032] Neither the adjacent bay switches on this side nor the opposite side have a pressure delay time.

[0033] The adjacent "node failure" GOOSE input;

[0034] The adjacent "node refuses to jump" GOOSE input;

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

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

[0037] Power restoration action.

[0038] This invention provides a protection device for a distribution network integrated primary and secondary ring main unit (PNU) line. The device includes multiple PNU integrated PNU ring main units, with the line between any two adjacent PNU ring main units designated as the line to be protected. One of the two adjacent PNU ring main units is designated as the local side, and the other as the opposite side. Each PNU integrated PNU ring main unit includes a power supply side incoming circuit breaker, multiple feeder circuit breakers, a ring main unit busbar, and multiple distribution terminals. The current flowing into the PNU ring main unit flows through the power supply side incoming circuit breaker into the ring main unit busbar, and then from the ring main unit busbar into the multiple feeder circuit breakers. Then it flows out; each circuit breaker is connected to a corresponding distribution terminal, and each distribution terminal is used to collect and control data of the connected circuit breaker; each circuit breaker and the corresponding connected distribution terminal form a bay unit, and the distribution terminals can communicate with each other; the distribution terminal of this bay 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 bay unit, it issues a command to control the tripping of the output of this side to complete the fault clearing; the distribution terminal of the opposite bay unit is used to send an action permission signal and, after receiving a node fault signal sent by this side, issue a command to control the tripping of the output of the opposite side to complete the fault isolation.

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

[0040] The monitoring subsystem is used to monitor the feeder status in real time;

[0041] The fault detection subsystem is used to identify faults in the interval unit and issue alarms in real time by analyzing monitoring data;

[0042] The fault isolation subsystem is used to isolate the fault by tripping the interval switch after locating the fault location, so as to reduce the scope of the fault's impact.

[0043] The power restoration subsystem is used to initiate power restoration operations after the fault is isolated, control the closing of switches in the relevant bays, and restore power supply to the non-faulty sections.

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

[0045] (1) Data transmission efficiency and reliability. Distributed feeder automation improves data transmission reliability and reduces transmission latency by directly mapping real-time data packet encoding to the data link layer, avoiding complex processing through the network and transport layers.

[0046] (2) Avoid blind operation of equipment. Traditionally, if only the current instantaneous overcurrent protection device is configured at the feeder outlet, there may be a risk of blind operation of the equipment, which may result in the entire feeder being cut off and also affect 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 experience judgment, and is easily affected by subjective factors. This protection system is highly efficient and accurate in identification through real-time data monitoring and analysis. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating the integrated primary and secondary ring network box line protection method for distribution networks according to an embodiment of the present invention.

[0049] Figure 2 This is a schematic diagram of the primary wiring of the secondary fusion complete ring network box according to Embodiment 1 of the present invention;

[0050] Figure 3 This is a schematic diagram of the primary wiring of a 10kV line according to an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram of a secondary fusion complete ring network box according to Embodiment 1 of the present invention;

[0052] Figure 5 This is a schematic diagram of the fault handling logic for the segmented switch according to an embodiment of the present invention;

[0053] Figure 6 This is a schematic diagram of the non-fault recovery logic of the interconnection switch in an embodiment of the present invention. Detailed Implementation

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

[0055] This invention provides a method for protecting integrated primary and secondary ring network box lines in distribution networks, such as... Figure 1 As shown, the method includes:

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

[0057] Step 102: If the power distribution terminal of this side bay unit detects a fault and triggers a node fault signal, and receives an action permission signal sent by the power distribution terminal of the opposite side bay unit, it issues a command to control the tripping of the local output circuit breaker to complete the fault clearing.

[0058] Step 103: The distribution terminal of the opposite bay unit sends an action permission signal, and after receiving the node fault signal sent from this side, it issues a command to control the opposite output to trip, thus completing the fault isolation.

[0059] This embodiment is mainly used to promptly disconnect the faulty part in the event of a fault in the 10 kV integrated primary and secondary ring network box line, so as to prevent the fault from spreading and escalating, and protect the stable operation of the 10 kV distribution network system.

[0060] A primary and secondary integrated ring main unit is a type of equipment in a power distribution system, mainly consisting of incoming and outgoing cabinets, as well as corresponding protection and control devices. It integrates primary and secondary side power distribution, protection, and control equipment into a single enclosure. (See also...) Figure 2 , Figure 3 and Figure 4In the ring main unit, circuit breakers 301, 303, 305, 307, 309, and 311 are bay circuit breakers. 301 is the incoming power supply circuit breaker, while 303, 305, 307, 309, and 311 are feeder circuit breakers. The copper plates connecting these circuit breakers form the ring main unit busbar. Current flows into the ring main unit from 301, through the busbar to the feeder circuit breakers 303, 305, 307, 309, and 311, and finally to the downstream user load. Unlike traditional ring main units, each bay circuit in this integrated primary and secondary ring main unit is equipped with a distribution terminal (protection and control device). The distribution terminal can collect and monitor data such as voltage, current, and switch information in real time for this circuit. In the event of a short circuit or other fault, the secondary protection device of this circuit enables the circuit breaker to selectively, rapidly, reliably, and sensitively isolate the fault. The device can not only realize the line protection function of this bay unit, but also realize the distributed feeder automation function based on the mutual communication of each power distribution terminal.

[0061] The specific operational logic of this embodiment is as follows:

[0062] Figure 2 The diagram shown is the primary main wiring diagram of a primary and secondary integrated ring network box. (See diagram for example.) Figure 3 As shown, the line protection range includes switch 303 in this ring main unit and switch 301 in the same ring main unit downstream of the line. Therefore, the switch on this side refers to... Figure 2 The switch shown in interval 303 refers to switch 301 of the downstream ring network box connected to this ring network box.

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

[0064] Fault clearance: After the power distribution terminal (protection and control device) of the switch on this side detects a fault, it triggers a "node fault" signal. At the same time, after receiving a "operation permission" signal from the power distribution terminal (protection and control device) of the switch on the opposite side, it trips the circuit breaker.

[0065] Fault isolation: When the power distribution terminal (protection and control device) of the switch on this side triggers the "operation permission" signal, and at the same time receives the "node fault" signal from the power distribution terminal (protection and control device) of the switch on the opposite side, it issues a command to trip the output circuit breaker and disconnect the switch on this side.

[0066] The line protection is blocked if any switch CT on either side of the line is disconnected. The corresponding line protection is blocked if the GOOSE communication of each distribution terminal (protection and control device) in each bay is abnormal.

[0067] "Action Allowed" Signal: The upstream switch in the fault area is allowed to operate. The distribution terminal (protection and control device) of this switch bay did not detect the CT disconnection. When the distribution terminal (protection and control device) of the bay received a "node fault" or a low voltage start, current surge start or zero sequence voltage start blocked by PT disconnection, and no fault was detected after a 20ms delay, the "Action Allowed" signal was issued.

[0068] Low-voltage start: When the amplitude of any phase voltage in the three phases falls below the low-voltage setting without any PT disconnection, the distribution terminal (protection and control device) of the time-limited switch is activated. The default low-voltage setting is 30% of the rated phase voltage.

[0069] Start-up due to sudden current change:

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

[0071] Where: T—sampling period, I QD —The start-up setpoint for the sudden change; i(t) is the current at time t, i(tT) is the current at time t minus one sampling period, and i(t-2T) is the current at time t minus two sampling periods.

[0072] When the sudden change in current of any phase exceeds the starting threshold three times consecutively, the distribution terminal (protection and control device) of the interval switch is activated.

[0073] Zero-sequence voltage start: The start signal of the distribution terminal (protection and control device) of the interval switch is collected when the zero-sequence voltage exceeds the zero-sequence voltage setting.

[0074] Protection settings: Protection settings are protective measures targeting specific values ​​or setpoints. In some systems or equipment, specific values ​​or setpoints may be set to protect their normal operation and stability. The purpose of protection settings is to ensure that the system does not exceed or deviate from these set value ranges during operation, thereby preventing system failures, equipment damage, or other adverse consequences.

[0075] The fault handling logic for the last switch (the last overhead line switch in a single-radial power supply network with distributed feeder automation) is as follows: After the start-up conditions are met, if the distribution terminal (protection and control device) does not detect a fault triggering the "action allowed" signal, and simultaneously receives a "node fault" signal from the opposite distribution terminal (protection and control device), the circuit breaker will trip. If a fault is detected, the distribution terminal (protection and control device) will trip its normal protection output and trigger the "node fault" signal.

[0076] The fault handling logic of the first switch (the first switch connected to the substation outgoing switch in a distribution network with distributed feeder automation function): If there is no voltage and no current at this line node after the first switch undervoltage protection is activated, the distribution terminal (protection and control device) will trip the switch at this node after the first switch undervoltage trip time limit is set.

[0077] Feeder switch (outgoing switch of ring mains cabinet in cable line in distribution network) fault handling logic: After the distribution terminal (protection and control device) of this bay detects a fault, the conventional protection trips and triggers the "node fault" signal. If a "bus trip command" is received and the switch is closed but 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 when the negative sequence voltage is greater than 8V, a "PT disconnection alarm" signal is sent after a 10-second delay. After the bus voltage returns to normal, the "PT disconnection alarm" signal returns after a 1.25-second extension.

[0079] CT disconnection logic:

[0080] 1. Maximum phase current greater than 0.02In;

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

[0082] If the above two conditions are met, a "CT disconnection alarm" will be reported after a 10-second delay, and an alarm signal will be issued by the device.

[0083] See Figure 6 The recovery logic includes:

[0084] In medium-voltage distribution networks with a closed-loop design and open-loop operation, the tie switch (a tie switch or sectionalizing switch used to isolate multiple power supplies, normally in the open position) in the distribution terminal (protection and control device) receives a signal indicating successful isolation and single-sided voltage loss, and controls the tie switch to close after a delay confirmation period. When the load prediction function is activated, the tie switch can only be closed after receiving a transfer permission simultaneously within the delay period.

[0085] Load prediction: Each node of the line refreshes its own load every 30 seconds. After the downstream of the fault area is successfully isolated, it sends a signal of successful isolation and the required transfer load. The transfer load is forwarded to the distribution terminals (protection and control 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 real-time load. When the remaining load is greater than the transfer load, it sends a transfer permission signal.

[0086] Power supply restoration charging and discharging conditions:

[0087] a) Charging conditions:

[0088] 1) The interval switch at this node is in the open position;

[0089] 2) Both adjacent switches on this side and the opposite side are under pressure;

[0090] 3) No discharge conditions.

[0091] (After all the above conditions are met, the circuit will switch to charging mode after a certain delay (default is 15s), and this interval switch will be considered an open loop point.)

[0092] b) Discharge conditions:

[0093] 1) Distributed FA function exits;

[0094] 2) Neither the adjacent bay switches on this side nor the opposite side have a pressure delay time (default is 15s);

[0095] 3) Input "Next-side node fault" GOOSE;

[0096] 4) Input the adjacent "node refuses to jump" GOOSE;

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

[0098] 6) The grounding switch is in the closed position;

[0099] 5) Power restoration action.

[0100] (Power supply is restored momentarily when any of the above conditions are met.)

[0101] To determine if there is pressure on the opposite side, you can use PT acquisition or subscribe to the GOOSE signal indicating that there is pressure on the opposite node.

[0102] Failure judgment conditions: If the switch changes from closed to open and there is no current during the failure period of the interval switch, the "Fault Isolation Successful" GOOSE output signal is triggered; if the switch at this node still does not trip during the failure period, the "Switch Refuses to Trip" GOOSE output signal is triggered. The time range should comply with Appendix C.

[0103] Distributed FA Enabling / Deactivation: Deactivation of any terminal's distributed FA soft or hard switch disables the entire line's intelligent distributed FA and enables conventional protection; activation of all terminals' distributed FA soft and hard switches enables the entire line's intelligent distributed FA. The activation and deactivation of the entire line's intelligent distributed FA are controlled by the output blocking and reset values ​​of the trunk switch.

[0104] Interlocking tripping requirements for switch failure: When a switch fails to trip, a "Switch Failure to Trip" GOOSE signal should be triggered. When a sectionalizing switch node receives a "Switch Failure to Trip" GOOSE signal from the other side, and its switch is in the closed position and has not tripped, it should immediately trip. Upon receiving a "Switch Failure to Trip" GOOSE signal from another node on the busbar, the sectionalizing switch trips and issues a "Busbar Trip Command". If the sectionalizing switch does not detect a fault and trips successfully, a "Fault Isolation Successful" GOOSE signal should be triggered.

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

[0106] (1) Data transmission efficiency and reliability. Distributed feeder automation improves data transmission reliability and reduces transmission latency by directly mapping real-time data packet encoding to the data link layer, avoiding complex processing through the network and transport layers.

[0107] (2) Avoid blind operation of equipment. Traditionally, if only the current instantaneous overcurrent protection device is configured at the feeder outlet, there may be a risk of blind operation of the equipment, which may result in the entire feeder being cut off and also affect 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 experience judgment, and is easily affected by subjective factors. This protection system is highly efficient and accurate in identification through real-time data monitoring and analysis.

[0109] This invention provides a protection device for a distribution network integrated primary and secondary ring main unit (PNU) line. The device includes multiple PNU integrated PNU ring main units, with the line between any two adjacent PNU ring main units designated as the line to be protected. One of the two adjacent PNU ring main units is designated as the local side, and the other as the opposite side. Each PNU integrated PNU ring main unit includes a power supply side incoming circuit breaker, multiple feeder circuit breakers, a ring main unit busbar, and multiple distribution terminals. The current flowing into the PNU ring main unit flows through the power supply side incoming circuit breaker into the ring main unit busbar, and then from the ring main unit busbar into the multiple feeder circuit breakers. Then it flows out; each circuit breaker is connected to a corresponding distribution terminal, and each distribution terminal is used to collect and control data of the connected circuit breaker; each circuit breaker and the corresponding connected distribution terminal form a bay unit, and the distribution terminals can communicate with each other; the distribution terminal of this bay 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 bay unit, it issues a command to control the tripping of the output of this side to complete the fault clearing; the distribution terminal of the opposite bay unit is used to send an action permission signal and, after receiving a node fault signal sent by this side, issue a command to control the tripping of the output of the opposite side to complete the fault isolation.

[0110] This embodiment's method, based on intelligent algorithms and line feeder characteristics, identifies variations and fault locations, enabling real-time monitoring and fault handling of various power system parameters. In this embodiment, the distribution terminal mainly consists of the following components:

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

[0112] Fault Detection Subsystem: Encapsulated and built into the distribution terminal (protection and control device) of each bay unit, this subsystem further applies the data collected by the monitoring subsystem. By analyzing the monitoring data, it identifies bay unit (feeder) faults in real time and issues alarms. This technology can quickly and accurately detect and locate various faults in the power system, including overload, short circuit, and grounding.

[0113] The fault isolation subsystem, encapsulated within the distribution terminal (protection and control device) of each bay unit, further utilizes the data collected by the monitoring subsystem. After locating the fault, it isolates the fault by tripping the bay switch to reduce the scope of its impact. This helps to minimize the impact of the fault, ensuring the stable operation of the power system. The time from protection action to successful fault isolation may only take tens of milliseconds.

[0114] The power restoration subsystem, encapsulated within the distribution terminals (protection and control devices) of each bay unit, further utilizes the data collected by the monitoring subsystem. After isolating the fault, it initiates the power restoration operation, controlling the closing of switches in the relevant bays to restore power to the non-faulty sections. The power restoration process is relatively rapid, potentially taking only 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 upgrading, and optimized operation of power systems, particularly offering significant advantages in fault detection and location, remote monitoring, and management. Specific application scenarios include status monitoring and fault handling of cable branches, utility poles, and equipment connected to substations, distribution rooms, and prefabricated substations.

[0115] The apparatus provided in this embodiment and the method embodiment described above belong to the same concept. For details of its implementation, please refer to the method embodiment, which will not be repeated here.

[0116] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0117] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for line protection of a distribution network one-two fusion complete ring main unit, characterized in that, The method comprises: determining that the line between any two adjacent distribution network primary and secondary fusion integrated ring network boxes is a to-be-protected line; determining any one of the two adjacent distribution network primary and secondary fusion integrated ring network boxes as a local side and the other as an opposite side; the distribution network primary and secondary fusion 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 power distribution terminals; the inflow current of the distribution network primary and secondary fusion 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 and then flows out; each circuit breaker is connected to one power distribution terminal respectively, and each power distribution terminal is used for collecting and controlling the connected circuit breaker; each circuit breaker and the corresponding connected power distribution terminal form an interval unit, and the power distribution terminals can communicate with each other; if the power distribution terminal of the local side interval unit detects a fault and receives an action permission signal sent by the power distribution terminal of the opposite side interval unit, a command is sent to control the local side outlet to trip, and fault removal is completed; the power distribution terminal of the opposite side interval unit sends an action permission signal, and receives a node fault signal sent by the local side, and sends a command to control the opposite side outlet to trip, and fault isolation is completed; the power distribution terminal of the opposite side interval unit sends an action permission signal, and receives a node fault signal sent by the local side, and sends a command to control the opposite side outlet to trip, and fault isolation is completed; if the power distribution terminal of the opposite side interval unit does not detect a CT disconnection, and receives a node fault or a low voltage start, a current mutation variable start or a zero sequence voltage start, and does not detect a fault after a delay of a preset time, an "action permission" signal is sent; the CT disconnection comprises: the power distribution terminal of the interval unit judges whether a preset CT disconnection protection condition is met; in the case where it is judged that the preset CT disconnection protection condition is met, a CT disconnection alarm is triggered after a delay of a preset third time length, and a device alarm signal is sent; 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 any phase current.

2. The method of claim 1, wherein the line protection method is a ring network method. the low voltage start is a power distribution terminal start signal of an interval switch when any one of three-phase voltages is lower than a low voltage setting value without PT disconnection; the low voltage setting value is 30% of the rated phase voltage; the current mutation variable start is a power distribution terminal start signal of an interval switch when any one of three-phase currents is greater than a mutation variable start setting value for three times continuously; the calculation formula is: where T is a sampling period, is a constant for the mutation variable, is the current at time t, is the current at time t minus one sampling period; is the current at time t minus two sampling periods; the zero sequence voltage start is a power distribution terminal start signal of an interval switch when a collected zero sequence voltage is greater than a zero sequence voltage setting value.

3. The method of claim 1, wherein the line protection method is a ring network method. if the circuit breaker of the local side interval unit is a terminal switch, the terminal switch is the most terminal overhead line switch configured with a distributed feeder automation function in a single radiation power distribution network framework; the power distribution terminal connected to the terminal switch trips in the case where no fault is detected and no action permission signal is received, and trips in the case where a fault is detected and a node fault signal is received. If the circuit breaker of the local interval unit is a first switch, the first switch is the first switch connected with the switch of the transformer substation in the distribution network configured with the distributed FA function; if there is no voltage and no current at the local line node after the first switch loss-of-voltage protection function is put into operation, the switch at the local node is tripped after the first switch loss-of-voltage tripping time limit is set; If the circuit breaker of the local interval unit is a feeder switch, the feeder switch is the switch of the ring main unit in the distribution network; in the case that the distribution terminal of the feeder switch detects a fault, the outlet is tripped and a node fault signal is triggered; in the case that the busbar tripping command is received and the switch is in the closed position, the outlet is tripped.

4. The method of claim 1, wherein the line protection method is a ring network method. When the GOOSE communication of the distribution terminal of the interval unit is abnormal, the CT disconnection blocks the busbar protection.

5. The method of claim 1, wherein the line protection method is a ring network method. When the busbar positive sequence voltage is less than 30V and the line has current or the negative sequence voltage is greater than 8V, the distribution terminal of the interval unit sends a PT disconnection alarm signal after a first preset time delay; and after the busbar voltage returns to normal, the PT disconnection alarm signal returns after a second preset time delay.

6. The method of claim 1, wherein the line protection method is a ring network method. The distribution terminal receives the isolation success and unilateral loss-of-voltage signal, and controls the tie switch to close after a delay confirmation time; When the load prediction function is put into operation, the tie switch is controlled to close after a delay time and the transfer of the load is completed after the tie switch is closed. The load prediction function is that the load of each node of the line is refreshed every first time interval, and after the isolation downstream of the fault area is successful, an isolation success signal and a required transfer load are sent, the transfer load is forwarded to the distribution terminals on both sides with the isolation success signal, and when the isolation success signal is received by the first switch of the non-fault line, the remaining load of the line is calculated according to the current capacity and the real-time load, and when the remaining load is greater than the transfer load, a transfer permission signal is sent.

7. The method of claim 6, wherein the line protection method is a ring network method. The distribution terminal executes the power supply recovery function under the charging condition; and does not execute the power supply recovery function under the discharging condition; The charging condition is that a preset first condition is met and a second time delay is met; The preset first condition is that: The interval switch at the local node is in the open position; and any adjacent interval switch on the local side and the opposite side has voltage; and there is no discharging condition; The discharging condition is that any one of the following preset second conditions is met: The distributed FA function is exited; The adjacent interval switches on the local side and the opposite side have no voltage for a certain time; The "node fault" GOOSE input of the adjacent side; The "node refusal to trip" GOOSE input of the adjacent side; The isolation switch is in the open position; The grounding switch is in the closed position; The power supply recovery action is performed. ​ 8. A primary and secondary fusion complete ring net box line protection device, characterized in that, The device comprises a plurality of distribution network primary and secondary fusion integrated ring network boxes, lines between any two adjacent distribution network primary and secondary fusion integrated ring network boxes are to be protected lines; any one of the two adjacent distribution network primary and secondary fusion integrated ring network boxes is determined as a local side, and the other is determined as an opposite side; the distribution network primary and secondary fusion 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; an inflow current of the distribution network primary and secondary fusion integrated ring network box flows into the ring network box bus through the power supply side incoming line circuit breaker, and then flows out after flowing into the plurality of feeder circuit breakers; each circuit breaker is connected with one distribution terminal respectively, and each distribution terminal is used for collecting and controlling the connected circuit breaker; each circuit breaker and the 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 for triggering a node fault signal after detecting a fault, and sending a command to control the local side outlet tripping after receiving an action permission signal sent by the distribution terminal of the opposite side interval unit, so as to complete fault removal; The distribution terminal of the opposite side interval unit is used for sending a command to control the opposite side outlet tripping after sending an action permission signal and receiving a node fault signal sent by the local side, so as to complete fault isolation; the distribution terminal of the opposite side interval unit sends an action permission signal, which comprises that the distribution terminal of the opposite side interval unit does not detect a CT disconnection, and receives a node fault or a low voltage start, a current mutation variable start or a zero sequence voltage start after a PT disconnection lockout, and does not detect a fault after a delay of a preset time, and sends an "action permission" signal; the CT disconnection comprises that the distribution terminal of the interval unit judges whether a preset CT disconnection protection condition is met; in the case that the preset CT disconnection protection condition is met, a CT disconnection alarm is triggered after a delay of a preset third time length, and a device alarm signal is sent; the preset CT disconnection protection condition is that a maximum phase current is greater than 0.02In, and the maximum phase current is greater than 4 times of any phase current.

9. The primary and secondary fusion set ring main unit line protection device according to claim 8, characterized in that, The distribution terminal comprises: A monitoring subsystem is used for monitoring a feeder state in real time; A fault detection subsystem is used for identifying an interval unit fault in real time and sending an alarm by analyzing monitoring data; A fault isolation subsystem is used for isolating a fault by opening an interval switch after locating a fault position, so as to reduce a fault influence range; A power supply recovery subsystem is used for starting a power supply recovery operation after isolating a fault, controlling a switch of a related interval to be closed, and recovering power supply of a non-fault section.

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