Non-channel protection distribution line fault isolation and self-healing method and system

Abstract

The invention discloses a non-channel protection distribution line fault isolation and self-healing method and system, belongs to the technical field of power distribution network fault processing, and solves the problem of how to reduce the distribution line fault isolation range and the power supply recovery time. When the current and the voltage suddenly change, it is indicated that a fault occurs near the section switch, and finally the working state of the section switch adjacent to the fault position is controlled according to the fault occurrence position and the fault type, so that the fault is isolated from two sides or the fault is isolated from the power supply side and power supply recovery of a non-fault area is achieved. A main station and a channel do not need to be built, investment cost is effectively reduced, dependence on communication is reduced, meanwhile, the upstream and downstream switches adjacent to the fault point only need to act once, isolation of the fault point can be accurately achieved, power supply of a non-fault section can be rapidly recovered, and power supply reliability of a power distribution line is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network fault processing, and relates to a distribution line fault isolation and self-healing method and system for non-channel protection. Background Art

[0002] The existing 10kV distribution line automation technology is difficult to meet the users' growing demand for high power supply reliability. The short-circuit fault handling of distribution lines generally adopts current protection based on time difference. The protection setting value calculation is difficult, the configuration is complicated, and it is difficult to balance selectivity and speed. The existing distribution line short-circuit fault handling technology has the following shortcomings: (1) When a fault occurs at any point in the distribution line, in order to ensure the safety of the transformer, the distribution line outlet protection action is usually taken, causing the outlet circuit breaker to trip and the entire line to lose power. As a result, the loads in the non-fault distribution line section will inevitably stop supplying power, resulting in the distribution line fault isolation range being too large and lacking selectivity.

[0003] (2) The distribution line fault handling technology that relies on communication channels has a complex system structure and low reliability, and cannot meet the safety and reliability requirements of distribution line fault isolation.

[0004] (3) It takes a long time to restore power after fault isolation. Since the fault can only be located in a certain section, it takes a long time to locate the fault, which in turn prolongs the power restoration time.

[0005] Prior art, such as the invention patent with application publication number CN102447246A, discloses a method for fault isolation and self-healing of a distribution network. However, this method does not provide countermeasures for different fault types and coordination schemes for various protections on the feeder under the new operating mode after the power transfer. After the power transfer, the protections may lose selectivity and additional equipment automatic switching devices may be required.

[0006] For example, the invention patent with application publication number CN116316487A discloses a fault self-healing method for distribution lines, which uses on-site FA to achieve fault isolation and power transfer. However, the switches used in the distribution lines involved in this method are all phase switches, and currently, phase switches are not widely installed in distribution lines, and the number of phase switches is small. At the same time, when the protected line is too short, the quick-break protection will have no protection range, and there is a serious problem of over-tripping.

[0007] For example, the invention patent with application publication number CN112436479A discloses an adaptive protection device suitable for distribution lines. This method can achieve different isolation requirements for different fault types, but does not consider the problem of on-site self-healing after fault isolation. Moreover, the input of the interconnecting switch after fault isolation depends on manual remote control closing of the master station, which requires reliance on communication, and instead prolongs the time for restoring power supply in non-fault areas.

[0008] For example, the invention patent with application publication number CN117559370A discloses an on-site feeder automation fault handling method, which uses outgoing line switches and section switches to implement an on-site FA solution. However, after a fault, the outgoing line switch first trips non-selectively, causing the entire distribution line to be out of power, expanding the scope of the power outage and increasing the number of operations and burden of the outgoing line switch. Summary of the invention

[0009] The technical problem to be solved by the present invention is how to reduce the fault isolation range and power supply restoration time of the distribution line.

[0010] The present invention solves the above technical problems through the following technical solutions: A non-channel protection distribution line fault isolation and self-healing method, comprising: S100, using a non-channel protection device to obtain three-phase current and three-phase voltage at the corresponding section switch in real time; S200, determining the fault type and fault location according to changes in the three-phase current and the three-phase voltage; S300. According to the fault type and the fault location, control the working state of the section switch adjacent to the fault location, and according to the working state of the section switch, choose to isolate the fault from both sides or isolate the fault from the power supply side.

[0011] Furthermore, it also includes multiple distribution lines, the ends of two adjacent distribution lines are connected by a connecting switch, and multiple section switches are arranged on the distribution line to divide a single distribution line into multiple sections of distribution lines. Each section of the distribution line is connected to one end of the branch circuit, and the other end of the branch circuit is connected to the load. A non-channel protection device is installed at each section switch.

[0012] Further, the S200 includes the following steps: S210, based on the increase of any two-phase currents in the three-phase currents and the decrease of the voltages of the same two phases, determine that the fault type is a two-phase short circuit; based on the positive sequence power direction when the fault type is a two-phase short circuit, determine whether the power flow is forward or reverse to determine the working state of the non-channel protection device; based on the negative sequence power direction when the fault type is a two-phase short circuit, determine whether the fault is forward or reverse to determine the fault location; S220, based on the fact that the currents of the three phases in the three-phase current are all increased, determining that the fault type is a three-phase short circuit; based on the fact that the fault type is a three-phase short circuit, determining the fault location according to the time difference coordination.

[0013] Further, the S300 includes the following steps: S310, if the fault is isolated from both sides, the tie switch automatically closes to restore power supply to the non-fault area; S320: If the fault is isolated from the power supply side, after the interconnecting switch is automatically closed, the non-channel protection device performs reverse overcurrent action to isolate the fault and restore power supply.

[0014] Furthermore, the S310 is specifically as follows: S311, based on the fault type being a two-phase short circuit, and the fault location being between two sectionalizers, the sectionalizer adjacent to the fault location and located on the power supply side is controlled to be disconnected after a first preset time interval, and then the sectionalizer adjacent to the fault location and located on the load side is controlled to be disconnected after a second preset time interval, so as to isolate the fault from both sides; after the sectionalizer on the load side is disconnected, the contact switch is automatically closed after a third preset time interval to restore power supply to the non-fault area; or, S312, based on the fault type being a two-phase short circuit, and the fault location being between the section switch and the tie switch, controlling the section switch to disconnect after a fifth preset time interval to isolate the fault from both sides; or, S313, based on the fault type being a three-phase short circuit, and the fault location being between the sectionalizing switch and the connecting switch, the sectionalizing switch is controlled to be disconnected after the fifth preset time, and the connecting switch is automatically closed after the third preset time; after the connecting switch is closed, the connecting switch is controlled to be disconnected after the sixth preset time, so as to isolate the fault from both sides.

[0015] Furthermore, the S320 is specifically: When the fault type is a three-phase short circuit and the fault location is between two section switches, or when the fault type is a two-phase short circuit and the accelerated low voltage protection module of the non-channel protection device located on the load side adjacent to the fault location fails, the section switch adjacent to the fault location and located on the power supply side is controlled to be disconnected after a first preset time interval to isolate the fault from the power supply side; after the section switch on the power supply side is disconnected, the connecting switch is automatically closed at a third preset time interval; after the connecting switch is closed, the section switch adjacent to the fault location and located on the load side is controlled to be disconnected at a fourth preset time interval to isolate the fault and restore power supply.

[0016] Furthermore, the time values ​​of the first preset time, the second preset time, the third preset time, the fourth preset time, the fifth preset time, and the sixth preset time are set according to the principle of step-type time limit coordination.

[0017] A non-channel protection distribution line fault isolation and self-healing system, comprising: An acquisition module, the acquisition module is used to acquire the three-phase current and three-phase voltage at the corresponding segment switch in real time by using a non-channel protection device; A determination module, the determination module is used to determine the fault type and fault location according to the changes of the three-phase current and the three-phase voltage; A control module is used to control the working state of a section switch adjacent to the fault location according to the fault type and the fault location, and to select to isolate the fault from both sides or from the power supply side according to the working state of the section switch.

[0018] Furthermore, it also includes multiple distribution lines, the ends of two adjacent distribution lines are connected by a connecting switch, and multiple section switches are arranged on the distribution line to divide a single distribution line into multiple sections of distribution lines. Each section of the distribution line is connected to one end of the branch circuit, and the other end of the branch circuit is connected to the load. A non-channel protection device is installed at each section switch.

[0019] Furthermore, the determination module includes: A two-phase short-circuit unit, the two-phase short-circuit unit is used to determine that the fault type is a two-phase short circuit based on the increase of any two-phase currents in the three-phase currents and the decrease of the same two-phase voltages; when the fault type is a two-phase short circuit, according to the positive sequence power direction, determine whether the power flow is forward or reverse, so as to determine the working state of the non-channel protection device; when the fault type is a two-phase short circuit, according to the negative sequence power direction, determine whether the fault is forward or reverse, so as to determine the fault location; The three-phase short-circuit unit is used to determine that the fault type is a three-phase short circuit based on the increase of the currents of the three phases in the three-phase current; when the fault type is a three-phase short circuit, the fault location is determined according to the time difference.

[0020] The advantages of the present invention are: The present invention firstly obtains the three-phase current and three-phase voltage at the segment switch connected to the non-channel protection device in real time through the non-channel protection device, and then analyzes the changes of the three-phase current and three-phase voltage. When the current and voltage suddenly change, it indicates that a fault occurs near the segment switch, and then the type of the fault is determined. Finally, according to the location and type of the fault, the working state of the segment switch adjacent to the fault location is controlled, so as to isolate the fault from both sides or isolate the fault from the power supply side and restore power supply to the non-fault area. The present invention does not rely on communication, does not need to build a main station and a channel, effectively reduces investment costs, and reduces dependence on communication. At the same time, the switches upstream and downstream of the adjacent fault point only need to act once to accurately isolate the fault point, can quickly restore power supply to the non-fault section, and improves the power supply reliability of the distribution line. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural diagram of a power distribution circuit according to a first embodiment of the present invention; Figure 2 This is a flow chart of a non-channel protection distribution line fault isolation and self-healing method according to the first embodiment of the present invention; FIG. 3 (a) to FIG. 3 (b) are schematic diagrams of the case where the fault position is located between the switch in the substation and the first section switch according to the first embodiment of the present invention; FIG. 4 (a) to FIG. 4 (b) are schematic diagrams of the first embodiment of the present invention when the fault position is located between the first section switch and the second section switch; 5(a) to 5(b) are schematic diagrams of the case where the fault position is located between the second section switch and the third section switch according to the first embodiment of the present invention; FIG. 6 (a) to FIG. 6 (b) are schematic diagrams of the first embodiment of the present invention when the fault position is located between the third segment and the tie switch; Figure 7 It is a structural diagram of a non-channel protection distribution line fault isolation and self-healing system according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments: Embodiment 1 like Figure 1 As shown, specifically, the present invention discloses a non-channel protected distribution line fault isolation and self-healing method, comprising at least two distribution lines, wherein the ends of two adjacent distribution lines are connected by a connecting switch, and a plurality of section switches are arranged on the distribution line to divide a single distribution line into a plurality of sections of distribution lines, each section of the distribution line is connected to one end of a branch circuit, and the other end of the branch circuit is connected to a load, and a non-channel protection device is installed at each section switch.

[0024] Furthermore, the interconnecting switch has an automatic closing function when one side loses pressure. When the distribution lines on both sides operate normally, the interconnecting switch is disconnected.

[0025] Furthermore, the distribution line operates in a single power source radial manner.

[0026] Furthermore, the non-channel protection device includes a forward overcurrent protection module, a reverse overcurrent protection module, and an accelerated low voltage protection module; the forward overcurrent protection module is used to detect whether the current exceeds the set forward threshold value to prevent damage to the equipment caused by overload or fault of the distribution line; the reverse overcurrent protection module is used to monitor and determine whether the current flows in the reverse direction. When a fault occurs, the reverse current may cause damage to the equipment; the accelerated low voltage protection module is used to protect against low voltage conditions. When the voltage at the section switch drops to the low voltage threshold, the protection action is triggered quickly to cut off the line.

[0027] In this embodiment, each first non-channel protection device located at the power supply side of the distribution line can be arranged inside the distribution station, and the non-channel protection device can be a three-stage overcurrent protection device.

[0028] In this embodiment, when there is no fault in the distribution network, the sectionalizer is in a closed state, and the non-channel protection device at the sectionalizer is not started; when a fault occurs in the distribution network, the non-channel protection device is started, and the corresponding sectionalizer is controlled to be disconnected to isolate the fault.

[0029] The working states of the interconnecting switch include closed and open states. The two adjacent distribution lines operate radially in a single power supply. When the distribution network operates normally, the interconnecting switch is in the open state. When the interconnecting switch is closed, the current can flow; when the interconnecting switch is open, the current cannot flow.

[0030] When a fault occurs in the distribution line, the non-channel protection device is activated and controls the section switch adjacent to the fault location to disconnect, isolating the fault from both ends or the power supply side. When the fault is isolated from both sides, the connecting switch will automatically close to restore power supply to the non-fault area; when the fault is isolated from the power supply side, after the connecting switch automatically closes, the reverse overcurrent protection module of the non-channel protection device is activated, thereby isolating the fault and restoring power supply.

[0031] In this embodiment, if Figure 1As shown, the ends of distribution line 1 and distribution line 2 are connected through a connecting switch, and section switch 1, section switch 2, and section switch 3 are arranged on distribution line 1 in sequence, and section switch 4, section switch 5, and section switch 6 are arranged on distribution line 2 in sequence, each distribution line is divided into four sections of distribution lines, each section of distribution line is connected to one end of the branch circuit, L10, L11, L12, L13, L20, L21, L22 and L23 in the figure are all branch circuits, and the other end of the branch circuit is connected to the load; PTU1, PTU2, PTU3, PTU4, PTU5 and PTU6 in the figure are all non-channel protection devices, which are respectively installed at section switch 1, section switch 2, section switch 3, section switch 4, section switch 5 and section switch 6. The first non-channel protection device on the power supply side of the main distribution line can be set inside the distribution station, and the non-channel protection device can be a three-stage overcurrent protection device, such as Figure 1 shown.

[0032] like Figure 2 As shown, the present invention discloses a non-channel protection distribution line fault isolation and self-healing method, specifically, it also includes the following steps: S100. Using a non-channel protection device, obtain three-phase current and three-phase voltage at a corresponding section switch in real time.

[0033] In this embodiment, the non-channel protection device measures the three-phase current and three-phase voltage at the section switch corresponding to the non-channel protection device through the current transformer and the voltage transformer arranged on the distribution line.

[0034] S200. Determine the fault type and fault location according to changes in the three-phase current and the three-phase voltage.

[0035] Furthermore, the S200 includes the following specific steps: S210, determining that the fault type is a two-phase short circuit based on an increase in any two-phase current among the three-phase currents and a decrease in the voltage of the same two phases; When the fault type is a two-phase short circuit, the power flow is determined to be forward or reverse according to the positive-sequence power direction to determine the working status of the non-channel protection device; when the fault type is a two-phase short circuit, the fault is determined to be forward or reverse according to the negative-sequence power direction to determine the fault location.

[0036] S220, based on the increase in currents of the three phases in the three-phase current, determine that the fault type is a three-phase short circuit; when the fault type is a three-phase short circuit, determine the fault location based on the time difference to ensure selectivity. In this embodiment, using the time difference to determine the fault location is a prior art.

[0037] In this embodiment, the three-phase current includes A-phase, B-phase and C-phase currents, and the three-phase voltage includes A-phase, B-phase and C-phase voltages; when phenomenon (1) the A-phase current increases, the B-phase current increases, the A-phase voltage decreases and the B-phase voltage decreases, or phenomenon (2) the A-phase current increases, the C-phase current increases, the A-phase voltage decreases and the C-phase voltage decreases, or phenomenon (3) the B-phase current increases, the C-phase current increases, the B-phase voltage decreases and the C-phase voltage decreases, etc. occurs, it can be determined that a two-phase short circuit has occurred.

[0038] When the fault type is determined to be a two-phase short circuit, the positive-sequence power direction is obtained, and the flow is determined to be forward (flow from the power supply side to the load side) or reverse (flow direction of the fault current caused by the fault) according to the positive-sequence power direction, and then the working state of the non-channel protection device is determined, that is, whether the non-channel protection device performs forward overcurrent protection or reverse overcurrent protection. When the positive-sequence power direction is consistent with the normal flow direction, the non-channel protection device is forward overcurrent protection. At this time, the overcurrent protection will trigger the corresponding protection action according to the magnitude of the fault current, cut off the circuit in the fault area, and prevent equipment damage; when the fault causes the positive-sequence power direction to reverse, that is, the flow flows in the reverse direction, the non-channel protection device will start the reverse overcurrent protection to prevent the reverse current caused by the fault in the system from causing damage to the equipment or system.

[0039] When the fault type is determined to be a two-phase short circuit, the negative sequence power direction is obtained, and the fault is determined to be forward or reverse according to the negative sequence power direction, thereby determining the specific location of the fault. If the negative sequence power exists and the direction is clear, the reverse or positive change of the negative sequence power indicates the source direction of the fault. For example, if the direction of the negative sequence power points to a certain end, it means that the fault may occur on the line at that end.

[0040] When the currents of the three phases of the three-phase current all increase, it indicates that the fault type is a three-phase short circuit. In this embodiment, when the A-phase current, the B-phase current, and the C-phase current all increase, it indicates that a three-phase short circuit has occurred.

[0041] S300. According to the fault type and the fault location, control the working state of the section switch adjacent to the fault location, and according to the working state of the section switch, choose to isolate the fault from both sides or isolate the fault from the power supply side.

[0042] Furthermore, the S300 includes the following specific steps: S310. If the fault is isolated from both sides, the interconnecting switch automatically closes to restore power supply to the non-faulty area.

[0043] Furthermore, the S310 is specifically as follows: S311. When the fault type is a two-phase short circuit and the fault location is between two section switches, the section switch adjacent to the fault location and located on the power supply side is controlled to be disconnected after a first preset time, and then the section switch adjacent to the fault location and located on the load side is controlled to be disconnected after a second preset time to isolate the fault from both sides; after the section switch on the load side is disconnected, the connecting switch is automatically closed after a third preset time to restore power supply to the non-fault area.

[0044] In this embodiment, when the fault type is a two-phase short circuit and the fault location is located between two section switches, first, after a first preset time interval, the forward overcurrent module of the non-channel protection device adjacent to the fault location and located on the power supply side is started, and the non-channel protection device on the power supply side performs forward overcurrent protection (Over-Current, OC), and controls the corresponding section switch to be disconnected; then, after a second preset time, the accelerated low-voltage module of the non-channel protection device adjacent to the fault location and located on the load side is started, and the non-channel protection device on the load side performs accelerated directional under-voltage protection (Aduv), and controls the corresponding section switch to be disconnected, and by starting two non-channel protection devices adjacent to the fault location, the fault is quickly and accurately isolated from both sides; finally, because the connecting switch has an automatic closing function when one side loses voltage, when the fault is isolated from both sides, the distribution line where the fault occurs will have no voltage, and the connecting switch is automatically closed after a third preset time, so that another distribution line supplies power to the distribution line where the fault occurs, and the power supply is restored to the non-fault area on the distribution line where the fault occurs. Among them, the first preset time and the second preset time can be set according to the principle of step-type time limit coordination, with a time difference of 0.1s, and the third preset time can be 10s.

[0045] S312: Based on the fact that the fault type is a two-phase short circuit and the fault location is between the section switch and the tie switch, the section switch is controlled to be disconnected after a fifth preset time interval to isolate the fault from both sides.

[0046] In this embodiment, when the fault type is a two-phase short circuit and the fault location is between the section switch and the connecting switch, the forward overcurrent module of the non-channel protection device is started after the fifth preset time interval, and the non-channel protection device performs forward overcurrent protection and controls the corresponding section switch to disconnect, thereby isolating the fault from both sides and restoring power supply to the non-fault area.

[0047] S313, based on the fault type being a three-phase short circuit, and the fault location being between the sectionalizing switch and the connecting switch, the sectionalizing switch is controlled to be disconnected after the fifth preset time, and the connecting switch is automatically closed after the third preset time; after the connecting switch is closed, the connecting switch is controlled to be disconnected after the sixth preset time, so as to isolate the fault from both sides.

[0048] In this embodiment, when the fault type is a three-phase short circuit and the fault location is between the section switch and the connecting switch, the forward overcurrent module of the non-channel protection device is first started after the fifth preset time, and the non-channel protection device performs forward overcurrent protection and controls the corresponding section switch to disconnect; then the connecting switch detects that one side has lost pressure, and the connecting switch automatically closes after the third preset time; finally, after the sixth preset time, the connecting switch is controlled to disconnect and forward overcurrent protection is performed to isolate the fault from both ends.

[0049] S320: If the fault is isolated from the power supply side, after the interconnecting switch is automatically closed, the non-channel protection device performs reverse overcurrent action to isolate the fault and restore power supply.

[0050] Furthermore, the S320 is specifically: S321. When the fault type is a three-phase short circuit and the fault location is between two section switches, the section switch adjacent to the fault location and located on the power supply side is controlled to be disconnected after a first preset time interval to isolate the fault from the power supply side; after the section switch on the power supply side is disconnected, the connecting switch is automatically closed at a third preset time interval; after the connecting switch is closed, the section switch adjacent to the fault location and located on the load side is controlled to be disconnected at a fourth preset time interval to isolate the fault and restore power supply.

[0051] In this embodiment, when the fault is a three-phase short circuit and the fault location is located between two section switches, first, after an interval of a first preset time, the forward overcurrent module of the non-channel protection device adjacent to the fault location and located on the power supply side is started, and the corresponding section switch is controlled to be disconnected, and the non-channel protection device on the power supply side performs forward overcurrent protection to isolate the fault from the power supply side; then the connecting switch detects a voltage loss on one side, and the connecting switch automatically closes after an interval of a third preset time; finally, after an interval of a fourth preset time, the reverse overcurrent protection module of the non-channel protection device adjacent to the fault location and located on the load side is started, and the non-channel protection device on the load side performs reverse overcurrent protection, controls the corresponding section switch to be disconnected, isolates the fault from both ends, and restores power supply to the non-fault area.

[0052] S322. Based on the fact that the fault type is a two-phase short circuit and the accelerating low voltage protection module of the non-channel protection device located on the load side adjacent to the fault position fails, the section switch adjacent to the fault position and located on the power supply side is controlled to be disconnected after a first preset time interval to isolate the fault from the power supply side; after the section switch on the power supply side is disconnected, the connecting switch is automatically closed at a third preset time interval; after the connecting switch is closed, the section switch adjacent to the fault position and located on the load side is controlled to be disconnected at a fourth preset time interval to isolate the fault and restore power supply.

[0053] In this embodiment, when the fault is a two-phase short circuit and the accelerated low-voltage protection module of the non-channel protection device located on the load side adjacent to the fault position fails, first, after an interval of a first preset time, the forward overcurrent module of the non-channel protection device adjacent to the fault position and located on the power supply side is started, the corresponding segmented switch is controlled to be disconnected, and the non-channel protection device on the power supply side performs forward overcurrent protection to isolate the fault from the power supply side; then the connecting switch detects that one side has lost voltage, and the connecting switch automatically closes after an interval of a third preset time; finally, after an interval of a fourth preset time, the reverse overcurrent protection module of the non-channel protection device adjacent to the fault position and located on the load side is started, the non-channel protection device on the load side performs reverse overcurrent protection, and the corresponding segmented switch is controlled to be disconnected, so that when the accelerated low-voltage protection of the non-channel protection device on the load side refuses to operate due to various reasons (such as excessive transition resistance), the fault is isolated from both ends and power supply is restored to the non-fault area.

[0054] like Figure 1 As shown, in this embodiment, the preset time values ​​involved in the station protection, non-channel protection device and tie switch are set according to the step-type time limit coordination principle, and the time difference is 0.1s. Figure 1 The direction of the middle arrow indicates the forward or reverse current direction. The time setting value of the non-channel protection device for station protection is set to 0.8s. The time setting value of the forward overcurrent protection (forward OC) of the non-channel protection devices PTU1 and PTU4 is 0.7s, the time setting value of the reverse overcurrent protection (reverse OC) is 0.1s, and the time setting value of the accelerated undervoltage protection (ADUV) is 0.8s+. In this embodiment, 0.8s+ means that the minimum time setting value of ADUV is 0.8s. The time setting value of ADUV will be adjusted according to the actual situation of the distribution line to maintain Minimum time setting or extended time setting; the time setting of the forward overcurrent protection of non-channel protection devices PTU2 and PTU5 is 0.6s, the time setting of the reverse overcurrent protection is 0.2s, and the time setting of the accelerated low-voltage protection is 0.7s+; the time setting of the forward overcurrent protection of non-channel protection devices PTU3 and PTU6 is 0.5s, the time setting of the reverse overcurrent protection is 0.3s, and the time setting of the accelerated low-voltage protection is 0.6s+; the time setting of the forward overcurrent protection and reverse overcurrent protection of the tie switch are both 0.4s.

[0055] As shown in Figure 3 (a), the fault type and fault location meet S311, the first preset time is 0.8s, the second preset time is 0.8s, and the third preset time is 10s; when a two-phase short circuit fault occurs between the substation switch and the first section switch, take Figure 3 (a) as an example, a two-phase short circuit fault occurs near the branch circuit L10 in the distribution line 1. When the main line distribution line fault is detected 0.8s later, the station protection is turned on, and the station protection performs overcurrent protection. Then, after 0.8s, the accelerated low voltage protection module of the non-channel protection device PTU1 is turned on, and the section switch 1 corresponding to PTU1 is controlled to be disconnected, thereby isolating the fault from both ends. When the contact switch detects that there is voltage on one side and no voltage on the other side, it closes after a delay of 10s to restore power supply to the non-fault area.

[0056] As shown in FIG3 (b), the fault type and fault location meet S321 or S322, the first preset time is 0.8s, the third preset time is 10s, and the fourth preset time is 0.1s; when a three-phase short circuit fault occurs between the switch in the substation and the first section switch, or a two-phase short circuit fault occurs but the accelerated low voltage protection module of the non-channel protection device corresponding to the first section switch fails, take FIG3 (b) as an example to illustrate, when a three-phase short circuit fault occurs near the branch circuit L10 in the distribution line 1, or a two-phase short circuit fault occurs near the branch circuit L10 in the distribution line 1 When a two-phase short circuit fault occurs but the accelerated low voltage protection module of the non-channel protection device PTU1 fails, the station protection is turned on 0.8s after detecting the fault in line 1 to perform overcurrent protection; then when the connecting switch detects that there is voltage on one side and no voltage on the other side, it is closed after a delay of 10s; finally, 0.1s later, the reverse overcurrent protection module of the non-channel protection device PTU1 is turned on, and the section switch 1 corresponding to PTU1 is controlled to be disconnected, and the non-channel protection device PTU1 performs reverse overcurrent protection, thereby isolating the fault from both ends and restoring power supply to the non-fault area.

[0057] As shown in Figure 4 (a), the fault type and fault location meet S311, the first preset time is 0.7s, the second preset time is 0.7s, and the third preset time is 10s; when a two-phase short circuit fault occurs between the first section switch and the second section switch on the distribution line, take Figure 4 (a) as an example to illustrate, when a two-phase short circuit fault occurs near the branch circuit L11 in the distribution line 1, the forward overcurrent protection module of the non-channel protection device PTU1 is turned on 0.7s after the fault of line 1 is detected, and the section switch 1 corresponding to PTU1 is controlled to be disconnected, and the non-channel protection device PTU1 performs forward overcurrent protection; then after 0.7s, the accelerated low voltage protection module in the non-channel protection device PTU2 is turned on, and the section switch 2 corresponding to PTU2 is controlled to be disconnected, thereby isolating the fault from both ends. When the tie switch detects that there is voltage on one side and no voltage on the other side, it closes after a delay of 10s to restore power supply to the non-fault area.

[0058] As shown in Figure 4 (b), the fault type and fault location meet S321 or S322, the first preset time is 0.7s, the third preset time is 10s, and the fourth preset time is 0.2s; when a three-phase short circuit fault occurs between the first section switch and the second section switch on the distribution line, or a two-phase short circuit fault occurs but the accelerated low voltage protection module of the non-channel protection device corresponding to the second section switch fails, take Figure 4 (b) as an example to illustrate, when a three-phase short circuit fault occurs near the branch circuit L11 in the distribution line 1, or a two-phase short circuit fault occurs near the branch circuit L11 in the line 1 of the distribution line but the non-channel protection device PTU2 When the accelerated low voltage protection module fails, the forward overcurrent protection module of the non-channel protection device PTU1 is turned on 0.7s after the fault in line 1 is detected, and the section switch 1 corresponding to PTU1 is controlled to be disconnected, and the non-channel protection device PTU1 performs forward overcurrent protection; then when the connecting switch detects that there is voltage on one side and no voltage on the other side, it is closed after a delay of 10s; finally, 0.2s later, the reverse overcurrent protection module of the non-channel protection device PTU2 is turned on, and the section switch 2 corresponding to PTU2 is controlled to be disconnected, and the non-channel protection device PTU2 performs reverse overcurrent protection, thereby isolating the fault from both ends and restoring power supply to the non-fault area.

[0059] As shown in Figure 5 (a), the fault type and fault location meet S311, the first preset time is 0.6s, the second preset time is 0.6s, and the third preset time is 10s; when a two-phase short circuit fault occurs between the second section switch and the third section switch on the distribution line, take Figure 5 (a) as an example to illustrate, when a two-phase short circuit fault occurs near the branch circuit L12 in the distribution line 1, the forward overcurrent protection module of the non-channel protection device PTU2 is turned on 0.6s after the fault of line 1 is detected, and the section switch 2 corresponding to PTU2 is controlled to be disconnected, and the non-channel protection device PTU2 performs forward overcurrent protection; then after 0.6s, the accelerated low voltage protection module of the non-channel protection device PTU3 is turned on, and the section switch 3 corresponding to PTU3 is controlled to be disconnected, thereby isolating the fault from both ends. When the tie switch detects that there is voltage on one side and no voltage on the other side, it closes after a delay of 10s to restore power supply to the non-fault area.

[0060] As shown in Figure 5 (b), the fault type and fault location meet S321 or S322, the first preset time is 0.6s, the third preset time is 10s, and the fourth preset time is 0.3s; when a three-phase short circuit fault occurs between the second section switch and the third section switch on the distribution line, or a two-phase short circuit fault occurs but the accelerated low voltage protection module of the non-channel protection device corresponding to the third section switch fails, take Figure 5 (b) as an example to illustrate, when a three-phase short circuit fault occurs near the branch circuit L12 in the distribution line 1, or a two-phase short circuit fault occurs near the branch circuit L12 in the line 1 of the distribution line but the accelerated low voltage protection module of the non-channel protection device PTU3 fails. When the low-speed low-voltage protection module fails, the forward overcurrent protection module of the non-channel protection device PTU2 is turned on 0.6s after the fault on line 1 is detected, and the section switch 2 corresponding to PTU2 is controlled to be disconnected, and the non-channel protection device PTU2 performs forward overcurrent protection; then when the connecting switch detects that there is voltage on one side and no voltage on the other side, it is closed after a delay of 10S; finally, the reverse overcurrent protection module of the non-channel protection device PTU3 is turned on 0.3s later, and the section switch 3 corresponding to PTU3 is controlled to be disconnected, and the non-channel protection device PTU3 performs reverse overcurrent protection, thereby isolating the fault from both ends and restoring power supply to the non-fault area.

[0061] As shown in Figure 6 (a), the fault type and fault location meet S312, and the fifth preset time is 0.5s; when a two-phase short circuit fault occurs between the third section switch and the connecting switch on the distribution line, taking Figure 6 (a) as an example, when a two-phase short circuit fault occurs near the branch circuit L13 in the distribution line 1, the forward overcurrent protection module of the non-channel protection device PTU3 is turned on 0.5s after the fault of line 1 is detected, and the section switch 3 corresponding to PTU3 is controlled to be disconnected, and the non-channel protection device PTU3 performs forward overcurrent protection, thereby isolating the fault from both ends.

[0062] As shown in Figure 6 (b), the fault type and fault location meet S313, the third preset time is 10s, the fifth preset time is 0.5s, and the sixth preset time is 0.4s; when a three-phase short circuit fault occurs between the third section switch and the tie switch on the distribution line, take Figure 6 (b) as an example to illustrate that when a three-phase short circuit fault occurs near the branch circuit L13 in the distribution line 1, the forward overcurrent protection module of the non-channel protection device PTU3 is turned on 0.5s after the fault of line 1 is detected, and the section switch 3 corresponding to PTU3 is controlled to be disconnected, and the non-channel protection device PTU3 performs forward overcurrent protection; then when the tie switch detects that there is voltage on one side and no voltage on the other side, it is closed after a delay of 10s; finally, the tie switch is disconnected after 0.4s, and forward overcurrent protection is performed. Thus, the fault is isolated from both ends.

[0063] This embodiment first obtains the three-phase current and three-phase voltage at the section switch connected to the non-channel protection device in real time through the non-channel protection device, and then analyzes the changes in the three-phase current and three-phase voltage. When the current and voltage suddenly change, it indicates that a fault has occurred near the section switch, and then the type of fault is determined. Finally, according to the location and type of the fault, the working state of the section switch adjacent to the fault location is controlled, so as to isolate the fault from both sides or isolate the fault from the power supply side and restore power supply to the non-fault area. This embodiment does not rely on communication, does not need to build a main station and a channel, effectively reduces investment costs, and reduces dependence on communication. At the same time, the switches upstream and downstream of the adjacent fault point only need to act once to accurately isolate the fault point, and can quickly restore power supply to the non-fault section, thereby improving the power supply reliability of the distribution line.

[0064] Embodiment 2 like Figure 7As shown, the present invention also discloses a non-channel protected distribution line fault isolation and self-healing system, comprising at least two distribution lines, the ends of two adjacent distribution lines are connected by a connecting switch, a plurality of section switches are arranged on the distribution line, a single distribution line is divided into a plurality of distribution lines, each section of the distribution line is connected to one end of a branch circuit, the other end of the branch circuit is connected to a load, and a non-channel protection device is installed at each section switch.

[0065] Furthermore, the interconnecting switch has an automatic closing function when one side loses pressure. When the distribution lines on both sides operate normally, the interconnecting switch is disconnected.

[0066] Furthermore, the distribution line operates in a single power source radial manner.

[0067] Furthermore, the non-channel protection device includes a forward overcurrent protection module, a reverse overcurrent protection module, and an accelerated low voltage protection module; the forward overcurrent protection module is used to detect whether the current exceeds the set forward threshold value to prevent damage to the equipment caused by overload or fault of the distribution line; the reverse overcurrent protection module is used to monitor and determine whether the current flows in the reverse direction. When a fault occurs, the reverse current may cause damage to the equipment; the accelerated low voltage protection module is used to protect against low voltage conditions. When the voltage at the section switch drops to the low voltage threshold, the protection action is triggered quickly to cut off the line.

[0068] In this embodiment, each first non-channel protection device located at the power supply side of the distribution line can be arranged inside the distribution station, and the non-channel protection device can be a three-stage overcurrent protection device.

[0069] In this embodiment, when there is no fault in the distribution network, the sectionalizer is in a closed state, and the non-channel protection device at the sectionalizer is not started; when a fault occurs in the distribution network, the non-channel protection device is started, and the corresponding sectionalizer is controlled to be disconnected to isolate the fault.

[0070] The working states of the interconnecting switch include closed and open states. The two adjacent distribution lines operate radially in a single power supply. When the distribution network operates normally, the interconnecting switch is in the open state. When the interconnecting switch is closed, the current can flow; when the interconnecting switch is open, the current cannot flow.

[0071] When a fault occurs in the distribution line, the non-channel protection device is activated and controls the section switch adjacent to the fault location to disconnect, isolating the fault from both ends or the power supply side. When the fault is isolated from both sides, the connecting switch will automatically close to restore power supply to the non-fault area; when the fault is isolated from the power supply side, after the connecting switch automatically closes, the reverse overcurrent protection module of the non-channel protection device is activated, thereby isolating the fault and restoring power supply.

[0072] The present invention discloses a non-channel protection distribution line fault isolation and self-healing system, which also includes an acquisition module, a determination module and a control module; The acquisition module is used to acquire the three-phase current and three-phase voltage at the corresponding section switch in real time by using the non-channel protection device; In this embodiment, the non-channel protection device measures the three-phase current and three-phase voltage at the section switch corresponding to the non-channel protection device through the current transformer and the voltage transformer arranged on the distribution line.

[0073] The determination module is used to determine the fault type and fault location according to the changes of the three-phase current and the three-phase voltage; Further, the determination module includes a two-phase short-circuit unit and a three-phase short-circuit unit; The two-phase short-circuit unit is used to determine that the fault type is a two-phase short circuit based on an increase in any two-phase current in the three-phase current and a decrease in the voltage of the same two phases; when the fault type is a two-phase short circuit, determine whether the power flow is forward or reverse according to the positive-sequence power direction to determine the working state of the non-channel protection device; when the fault type is a two-phase short circuit, determine whether the fault is forward or reverse according to the negative-sequence power direction to determine the fault location.

[0074] The three-phase short-circuit unit is used to determine that the fault type is a three-phase short circuit based on the increase in the currents of the three phases in the three-phase current; when the fault type is a three-phase short circuit, the fault location is determined according to the time difference to ensure selectivity. In this embodiment, the use of time difference to determine the fault location is a prior art.

[0075] In this embodiment, the three-phase current includes A-phase, B-phase and C-phase currents, and the three-phase voltage includes A-phase, B-phase and C-phase voltages; when phenomenon (1) the A-phase current increases, the B-phase current increases, the A-phase voltage decreases and the B-phase voltage decreases, or phenomenon (2) the A-phase current increases, the C-phase current increases, the A-phase voltage decreases and the C-phase voltage decreases, or phenomenon (3) the B-phase current increases, the C-phase current increases, the B-phase voltage decreases and the C-phase voltage decreases, etc. occurs, it can be determined that a two-phase short circuit has occurred.

[0076] When the fault type is determined to be a two-phase short circuit, the positive-sequence power direction is obtained, and the flow is determined to be forward (flow from the power supply side to the load side) or reverse (flow direction of the fault current caused by the fault) according to the positive-sequence power direction, and then the working state of the non-channel protection device is determined, that is, whether the non-channel protection device performs forward overcurrent protection or reverse overcurrent protection. When the positive-sequence power direction is consistent with the normal flow direction, the non-channel protection device is forward overcurrent protection. At this time, the overcurrent protection will trigger the corresponding protection action according to the magnitude of the fault current, cut off the circuit in the fault area, and prevent equipment damage; when the fault causes the positive-sequence power direction to reverse, that is, the flow flows in the reverse direction, the non-channel protection device will start the reverse overcurrent protection to prevent the reverse current caused by the fault in the system from causing damage to the equipment or system.

[0077] When the fault type is determined to be a two-phase short circuit, the negative sequence power direction is obtained, and the fault is determined to be forward or reverse according to the negative sequence power direction, thereby determining the specific location of the fault. If the negative sequence power exists and the direction is clear, the reverse or positive change of the negative sequence power indicates the source direction of the fault. For example, if the direction of the negative sequence power points to a certain end, it means that the fault may occur on the line at that end.

[0078] When the currents of the three phases of the three-phase current all increase, it indicates that the fault type is a three-phase short circuit. In this embodiment, when the A-phase current, the B-phase current, and the C-phase current all increase, it indicates that a three-phase short circuit has occurred.

[0079] The control module is used to control the working state of the section switch adjacent to the fault location according to the fault type and the fault location, and to select to isolate the fault from both sides or from the power supply side according to the working state of the section switch; Furthermore, the control module includes a two-side isolation unit and a power supply side isolation unit: The two-side isolation unit is used to determine if the fault is isolated from both sides, and the connecting switch is automatically closed to restore power supply to the non-fault area.

[0080] Furthermore, the isolation units on both sides are specifically: When the fault type is a two-phase short circuit and the fault location is between two section switches, the section switch adjacent to the fault location and located on the power supply side is controlled to be disconnected after the first preset time, and then the section switch adjacent to the fault location and located on the load side is controlled to be disconnected after the second preset time to isolate the fault from both sides; after the section switch on the load side is disconnected, the connecting switch is automatically closed after the third preset time to restore power supply to the non-fault area.

[0081] In this embodiment, when the fault type is a two-phase short circuit and the fault location is located between two section switches, first, after a first preset time interval, the forward overcurrent module of the non-channel protection device adjacent to the fault location and located on the power supply side is started, and the non-channel protection device on the power supply side performs forward overcurrent protection (Over-Current, OC), and controls the corresponding section switch to be disconnected; then, after a second preset time, the accelerated low-voltage module of the non-channel protection device adjacent to the fault location and located on the load side is started, and the non-channel protection device on the load side performs accelerated directional under-voltage protection (Aduv), and controls the corresponding section switch to be disconnected, and by starting two non-channel protection devices adjacent to the fault location, the fault is quickly and accurately isolated from both sides; finally, because the connecting switch has an automatic closing function when one side loses voltage, when the fault is isolated from both sides, the distribution line where the fault occurs will have no voltage, and the connecting switch is automatically closed after a third preset time, so that another distribution line supplies power to the distribution line where the fault occurs, and the power supply is restored to the non-fault area on the distribution line where the fault occurs. Among them, the first preset time and the second preset time can be set according to the principle of step-type time limit coordination, with a time difference of 0.1s, and the third preset time can be 10s.

[0082] When the fault type is a two-phase short circuit and the fault location is between the section switch and the contact switch, the section switch is controlled to be disconnected after a fifth preset time interval to isolate the fault from both sides.

[0083] In this embodiment, when the fault type is a two-phase short circuit and the fault location is between the section switch and the connecting switch, the forward overcurrent module of the non-channel protection device is started after the fifth preset time interval, and the non-channel protection device performs forward overcurrent protection and controls the corresponding section switch to disconnect, thereby isolating the fault from both sides and restoring power supply to the non-fault area.

[0084] When the fault type is a three-phase short circuit and the fault location is between the section switch and the connecting switch, the section switch is controlled to be disconnected after the fifth preset time, and the connecting switch is automatically closed after the third preset time; after the connecting switch is closed, the connecting switch is controlled to be disconnected after the sixth preset time to isolate the fault from both sides.

[0085] In this embodiment, when the fault type is a three-phase short circuit and the fault location is between the section switch and the connecting switch, the forward overcurrent module of the non-channel protection device is first started after the fifth preset time, and the non-channel protection device performs forward overcurrent protection and controls the corresponding section switch to disconnect; then the connecting switch detects that one side has lost pressure, and the connecting switch automatically closes after the third preset time; finally, after the sixth preset time, the connecting switch is controlled to disconnect and forward overcurrent protection is performed to isolate the fault from both ends.

[0086] The power supply side isolation unit is used to determine if the fault is isolated from the power supply side, and after the tie switch is automatically closed, the non-channel protection device performs a reverse overcurrent action to isolate the fault and restore power supply.

[0087] Furthermore, the power supply side isolation unit is specifically: When the fault type is a three-phase short circuit and the fault location is between two section switches, the section switch adjacent to the fault location and located on the power supply side is controlled to be disconnected after the first preset time interval to isolate the fault from the power supply side; after the section switch on the power supply side is disconnected, the connecting switch is automatically closed at a third preset time interval; after the connecting switch is closed, the section switch adjacent to the fault location and located on the load side is controlled to be disconnected at a fourth preset time interval to isolate the fault and restore power supply.

[0088] In this embodiment, when the fault is a three-phase short circuit and the fault location is located between two section switches, first, after an interval of a first preset time, the forward overcurrent module of the non-channel protection device adjacent to the fault location and located on the power supply side is started, and the corresponding section switch is controlled to be disconnected, and the non-channel protection device on the power supply side performs forward overcurrent protection to isolate the fault from the power supply side; then the connecting switch detects a voltage loss on one side, and the connecting switch automatically closes after an interval of a third preset time; finally, after an interval of a fourth preset time, the reverse overcurrent protection module of the non-channel protection device adjacent to the fault location and located on the load side is started, and the non-channel protection device on the load side performs reverse overcurrent protection, controls the corresponding section switch to be disconnected, isolates the fault from both ends, and restores power supply to the non-fault area.

[0089] Based on the fact that the fault type is a two-phase short circuit and the accelerated low voltage protection module of the non-channel protection device located on the load side adjacent to the fault position fails, the section switch adjacent to the fault position and located on the power supply side is controlled to be disconnected after a first preset time interval to isolate the fault from the power supply side; after the section switch on the power supply side is disconnected, the connecting switch is automatically closed at a third preset time interval; after the connecting switch is closed, the section switch adjacent to the fault position and located on the load side is controlled to be disconnected at a fourth preset time interval to isolate the fault and restore power supply.

[0090] In this embodiment, when the fault is a two-phase short circuit and the accelerated low-voltage protection module of the non-channel protection device located on the load side adjacent to the fault position fails, first, after an interval of a first preset time, the forward overcurrent module of the non-channel protection device adjacent to the fault position and located on the power supply side is started, the corresponding segmented switch is controlled to be disconnected, and the non-channel protection device on the power supply side performs forward overcurrent protection to isolate the fault from the power supply side; then the connecting switch detects that one side has lost voltage, and the connecting switch automatically closes after an interval of a third preset time; finally, after an interval of a fourth preset time, the reverse overcurrent protection module of the non-channel protection device adjacent to the fault position and located on the load side is started, the non-channel protection device on the load side performs reverse overcurrent protection, and the corresponding segmented switch is controlled to be disconnected, so that when the accelerated low-voltage protection of the non-channel protection device on the load side refuses to operate due to various reasons (such as excessive transition resistance), the fault is isolated from both ends and power supply is restored to the non-fault area.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-channel protection distribution line fault isolation and self-healing method, characterized in that: include: S100, using a non-channel protection device to obtain the three-phase current and three-phase voltage at the corresponding segment switch in real time, wherein the non-channel protection device includes a forward overcurrent protection module, a reverse overcurrent protection module, and an accelerated low voltage protection module; S200, determining the fault type and fault location according to changes in the three-phase current and the three-phase voltage; S300. According to the fault type and the fault location, control the working state of the section switch adjacent to the fault location, and according to the working state of the section switch, choose to isolate the fault from both sides or isolate the fault from the power supply side.

2. A non-channel protection distribution line fault isolation and self-healing method according to claim 1, characterized in that: It also includes multiple distribution lines, the ends of two adjacent distribution lines are connected by a connecting switch, and multiple section switches are arranged on the distribution line to divide a single distribution line into multiple sections. Each section of the distribution line is connected to one end of a branch circuit, and the other end of the branch circuit is connected to a load. A non-channel protection device is installed at each section switch.

3. A non-channel protection distribution line fault isolation and self-healing method according to claim 1, characterized in that: The S200 includes: S210, based on the increase of any two-phase currents in the three-phase currents and the decrease of the voltages of the same two phases, determine that the fault type is a two-phase short circuit; based on the positive sequence power direction when the fault type is a two-phase short circuit, determine whether the power flow is forward or reverse to determine the working state of the non-channel protection device; based on the negative sequence power direction when the fault type is a two-phase short circuit, determine whether the fault is forward or reverse to determine the fault location; S220, based on the fact that the currents of the three phases in the three-phase current are all increased, determining that the fault type is a three-phase short circuit; based on the fact that the fault type is a three-phase short circuit, determining the fault location according to the time difference coordination.

4. A non-channel protection distribution line fault isolation and self-healing method according to claim 3, characterized in that: The S300 includes: S310, if the fault is isolated from both sides, the tie switch automatically closes to restore power supply to the non-fault area; S320: If the fault is isolated from the power supply side, after the interconnecting switch is automatically closed, the non-channel protection device performs reverse overcurrent action to isolate the fault and restore power supply.

5. A non-channel protection distribution line fault isolation and self-healing method according to claim 4, characterized in that: The S310 is specifically as follows: S311, based on the fault type being a two-phase short circuit, and the fault location being between two sectionalizers, after a first preset time interval, the sectionalizer adjacent to the fault location and located on the power supply side is controlled to be disconnected, and then after a second preset time interval, the sectionalizer adjacent to the fault location and located on the load side is controlled to be disconnected, so as to isolate the fault from both sides; After the section switch on the load side is disconnected, the contact switch is automatically closed after a third preset time interval to restore power supply to the non-fault area; or, S312, based on the fault type being a two-phase short circuit, and the fault location being between the section switch and the tie switch, controlling the section switch to disconnect after a fifth preset time interval to isolate the fault from both sides; or, S313, based on the fault type being a three-phase short circuit, and the fault location being between the sectionalizing switch and the connecting switch, the sectionalizing switch is controlled to be disconnected after the fifth preset time, and the connecting switch is automatically closed after the third preset time; after the connecting switch is closed, the connecting switch is controlled to be disconnected after the sixth preset time, so as to isolate the fault from both sides.

6. A non-channel protection distribution line fault isolation and self-healing method according to claim 5, characterized in that: The S320 is specifically: When the fault type is a three-phase short circuit and the fault location is between two section switches, or when the fault type is a two-phase short circuit and the accelerating low voltage protection module of the non-channel protection device located on the load side adjacent to the fault location fails, after a first preset time interval, the section switch adjacent to the fault location and located on the power supply side is controlled to be disconnected to isolate the fault from the power supply side; After the sectionalizing switch on the power supply side is disconnected, the contact switch is automatically closed after the third preset time interval; After the tie switch is closed, the section switch adjacent to the fault location and located on the load side is controlled to be opened at a fourth preset time interval to isolate the fault and restore power supply.

7. A non-channel protection distribution line fault isolation and self-healing method according to claim 6, characterized in that: The time values ​​of the first preset time, the second preset time, the third preset time, the fourth preset time, the fifth preset time and the sixth preset time are set according to the principle of step-type time limit coordination.

8. A non-channel protection distribution line fault isolation and self-healing system, characterized in that: include: An acquisition module, the acquisition module is used to acquire the three-phase current and three-phase voltage at the corresponding segment switch in real time by using a non-channel protection device; A determination module, the determination module is used to determine the fault type and fault location according to the changes of the three-phase current and the three-phase voltage; A control module is used to control the working state of a section switch adjacent to the fault location according to the fault type and the fault location, and to select to isolate the fault from both sides or from the power supply side according to the working state of the section switch.

9. A non-channel protection distribution line fault isolation and self-healing system according to claim 8, characterized in that: It also includes multiple distribution lines, the ends of two adjacent distribution lines are connected by a connecting switch, and multiple section switches are arranged on the distribution line to divide a single distribution line into multiple sections. Each section of the distribution line is connected to one end of a branch circuit, and the other end of the branch circuit is connected to a load. A non-channel protection device is installed at each section switch.

10. A non-channel protection distribution line fault isolation and self-healing system according to claim 8, characterized in that: The determination module comprises: A two-phase short circuit unit, wherein the two-phase short circuit unit determines that the fault type is a two-phase short circuit based on an increase in any two-phase current among the three-phase currents and a decrease in the voltage of the same two phases; when the fault type is a two-phase short circuit, the power flow is determined to be forward or reverse according to the positive sequence power direction to determine the working state of the non-channel protection device; when the fault type is a two-phase short circuit, the fault is determined to be forward or reverse according to the negative sequence power direction to determine the fault location; A three-phase short circuit unit, wherein the three-phase short circuit unit determines that the fault type is a three-phase short circuit based on the increase of the currents of the three phases in the three-phase current; when the fault type is a three-phase short circuit, the fault location is determined according to the time difference.

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