A method and system for fault isolation and self-healing of a non-channel protected distribution line

Abstract

A method and system for fault isolation and self-healing of a distribution line without channel protection, belonging to the technical field of distribution network fault processing, to solve the problem of how to reduce the fault isolation range and power supply restoration time of the distribution line. First, the non-channel protection device of the present invention obtains the three-phase current and three-phase voltage at the sectionalizing switch in real time. When the current and voltage mutate, it indicates that a fault has occurred near the sectionalizing switch. Finally, according to the location and type of the fault, the working state of the sectionalizing switch adjacent to the fault location is controlled, so as to achieve isolating the fault from both sides or isolating the fault from the power supply side and restoring the power supply to the non-fault area. The present invention does not rely on communication, does not require the construction of a master station and a channel, effectively reduces the investment cost, reduces the dependence on communication, and 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 the power supply to the non-fault section, and improves the power supply reliability of the distribution line.

Description

Technical Field

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

[0002] The existing 10kV distribution line automation technology is difficult to meet the increasing requirements of users for high power supply reliability. For the disposal of short-circuit faults in distribution lines, current protection based on time grading is generally adopted. The calculation of protection settings is difficult and the configuration is complicated, and it is difficult to balance selectivity and rapidity. The existing distribution line short-circuit fault handling technology has the following deficiencies:

[0003] (1) When a fault occurs at any point on the distribution line, in order to ensure the safety of the transformer, the protection at the outlet of the distribution line usually acts, resulting in the tripping of the outlet circuit breaker and a power outage of the entire line. As a result, the loads on the non-faulty sections of the distribution line will inevitably stop being powered, causing an overly large fault isolation range of the distribution line and a lack of selectivity.

[0004] (2) For the distribution line fault handling technology that relies on communication channels, its system composition is complex and the reliability is low, and it cannot meet the safety and reliability requirements for distribution line fault isolation.

[0005] (3) The power supply restoration time after fault isolation is long. Since the fault can only be located to a certain section, the time required for fault location is long, which in turn prolongs the power supply restoration time.

[0006] The prior art, such as the invention patent with the application publication number CN102447246A, discloses a method for distribution network fault isolation and self-healing. However, this method does not provide countermeasures for different fault types and the coordination scheme of each protection on the feeder under the new operation mode after transfer. After transfer, selectivity may be lost between protections, and an additional device automatic switching device needs to be added.

[0007] For example, the invention patent with the application publication number CN116316487A discloses a fault self-healing method for distribution lines, which uses local FA to achieve fault isolation and transfer. However, the switches adopted on the distribution lines involved in this method are all single-phase switches, and currently, single-phase switches are not popularly installed on distribution lines, and the number of single-phase switches is small. At the same time, when the protected line is too short in this method, the quick-break protection has no protection range, resulting in a serious problem of overstepping tripping.

[0008] The invention patent with the application publication number CN112436479A discloses an adaptive protection device applicable to distribution lines. This method can achieve different isolation requirements for different fault types, but it does not consider the in-situ self-healing problem after fault isolation. Moreover, the closing of the tie switch after fault isolation relies on manual remote control closing by the master station, which requires communication and instead prolongs the power restoration time of the non-fault area.

[0009] The invention patent with the application publication number CN117559370A discloses an in-situ feeder automation fault handling method, which uses the outgoing line switch and sectionalizing switch to implement the in-situ FA solution. However, after the fault, the outgoing line switch trips non-selectively first, resulting in a power outage of the entire distribution line, expanding the power outage range and increasing the operation times and burden of the outgoing line switch. Summary of the Invention

[0010] The technical problem to be solved by the present invention is how to reduce the fault isolation range and power restoration time of the distribution line.

[0011] The present invention solves the above technical problems through the following technical solutions:

[0012] A non-channel protection method for fault isolation and self-healing of distribution lines, including:

[0013] S100. Use a non-channel protection device to obtain the three-phase current and three-phase voltage at the corresponding sectionalizing switch in real time;

[0014] S200. Determine the fault type and fault location according to the changes in the three-phase current and three-phase voltage;

[0015] S300. According to the fault type and fault location, control the working state of the sectionalizing switch adjacent to the fault location, and according to the working state of the sectionalizing switch, select to isolate the fault from both sides or isolate the fault from the power source side.

[0016] Furthermore, it includes multiple distribution lines. The ends of two adjacent distribution lines are connected by a tie switch. Multiple sectionalizing 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 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 sectionalizing switch.

[0017] Furthermore, the S200 includes the following steps:

[0018] S210. Determine that the fault type is a two-phase short circuit based on the increase of any two-phase currents in the three-phase current and the decrease of the same two-phase voltages. 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 operating 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.

[0019] S220. Determine that the fault type is a three-phase short circuit based on the increase of all three-phase currents in the three-phase current. When the fault type is a three-phase short circuit, determine the fault location according to the time-step coordination.

[0020] Further, the S300 includes the following steps:

[0021] S310. If the fault is isolated from both sides, the tie switch automatically closes to restore power supply to the non-faulty area.

[0022] S320. If the fault is isolated from the power supply side, after the tie switch automatically closes, the non-channel protection device performs a reverse overcurrent operation to isolate the fault and restore power supply.

[0023] Further, the S310 is specifically as follows:

[0024] S311. When the fault type is a two-phase short circuit and the fault location is between two sectional switches, after an interval of the first preset time, control the sectional switch adjacent to the fault location and on the power supply side to disconnect, and then after an interval of the second preset time, control the sectional switch adjacent to the fault location and on the load side to disconnect, so as to isolate the fault from both sides. After the sectional switch on the load side disconnects, after an interval of the third preset time, the tie switch automatically closes to restore power supply to the non-faulty area; or,

[0025] S312. When the fault type is a two-phase short circuit and the fault location is between the sectional switch and the tie switch, after an interval of the fifth preset time, control the sectional switch to disconnect to isolate the fault from both sides; or,

[0026] S313. When the fault type is a three-phase short circuit and the fault location is between the sectional switch and the tie switch, after an interval of the fifth preset time, control the sectional switch to disconnect, and after an interval of the third preset time, the tie switch automatically closes. After the tie switch closes, after an interval of the sixth preset time, control the tie switch to disconnect to isolate the fault from both sides.

[0027] Further, the S320 is specifically as follows:

[0028] Based on the fault type being a three-phase short circuit and the fault location being between two sectionalizing switches, or based on the fault type being a two-phase short circuit and the accelerating low-voltage protection module of the non-channel protection device adjacent to the fault location on the load side malfunctioning, after an interval of the first preset time, control the sectionalizing switch adjacent to the fault location and on the source side to disconnect, isolating the fault from the source side; after the sectionalizing switch on the source side disconnects, after an interval of the third preset time, the tie switch automatically closes; after the tie switch closes, after an interval of the fourth preset time, control the sectionalizing switch adjacent to the fault location and on the load side to disconnect, so as to isolate the fault and restore power supply.

[0029] Furthermore, the time settings 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 stepped time limit coordination.

[0030] A non-channel protection power distribution line fault isolation and self-healing system, comprising:

[0031] An acquisition module, which is used to use the non-channel protection device to acquire the three-phase current and three-phase voltage at the corresponding sectionalizing switch in real time;

[0032] A determination module, which is used to determine the fault type and fault location according to the changes in the three-phase current and three-phase voltage;

[0033] A control module, which is used to control the working state of the sectionalizing switch adjacent to the fault location according to the fault type and fault location, and select to isolate the fault from both sides or isolate the fault from the source side according to the working state of the sectionalizing switch.

[0034] Furthermore, it also includes multiple power distribution lines. The ends of two adjacent power distribution lines are connected by a tie switch. Multiple sectionalizing switches are arranged on the power distribution line, dividing a single power distribution line into multiple sections of power distribution lines. Each section of power 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 sectionalizing switch.

[0035] Furthermore, the determination module includes:

[0036] A two-phase short circuit unit, which is used to determine that the fault type is a two-phase short circuit based on any two-phase currents in the three-phase current increasing and the same two-phase voltages decreasing; 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;

[0037] Three-phase short-circuit unit, which is used to determine that the fault type is three-phase short-circuit based on the increase of the currents of all three phases in the three-phase current; and determine the fault location according to the time-grade coordination when the fault type is three-phase short-circuit.

[0038] The advantages of the present invention are as follows:

[0039] The present invention first obtains the three-phase current and three-phase voltage at the sectional 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 mutate, it indicates that a fault has occurred near the sectional switch, and then determines the type of the fault. Finally, according to the location and type of the fault, the working state of the sectional switch adjacent to the fault location is controlled, so as to realize isolating the fault from both sides or isolating the fault from the power supply side and restoring the power supply of the non-fault area. The present invention does not rely on communication, does not require the construction of a master station and a channel, effectively reduces the investment cost, reduces the dependence on communication, and at the same time, the switches upstream and downstream of the fault point only need to act once to accurately isolate the fault point, can quickly restore the power supply of the non-fault section, and improves the power supply reliability of the distribution line. Description of the Drawings

[0040] Figure 1 is the structural diagram of the distribution line in the first embodiment of the present invention;

[0041] Figure 2 is the flowchart of a non-channel protection method for isolating and self-healing distribution line faults in the first embodiment of the present invention;

[0042] Figures 3(a) to 3(b) are schematic diagrams when the fault location is between the substation switch and the first sectional switch in the first embodiment of the present invention;

[0043] Figures 4(a) to 4(b) are schematic diagrams when the fault location is between the first sectional switch and the second sectional switch in the first embodiment of the present invention;

[0044] Figures 5(a) to 5(b) are schematic diagrams when the fault location is between the second sectional switch and the third sectional switch in the first embodiment of the present invention;

[0045] Figures 6(a) to 6(b) are schematic diagrams when the fault location is between the third sectional switch and the tie switch in the first embodiment of the present invention;

[0046] Figure 7 is the structural diagram of a non-channel protection system for isolating and self-healing distribution line faults in the second embodiment of the present invention. Detailed Embodiments

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will, in combination with the embodiments of the present invention, clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0048] The following further describes the technical solutions of the present invention in combination with the accompanying drawings of the specification and specific embodiments:

[0049] Embodiment 1

[0050] As Figure 1 shown, specifically, the present invention discloses a method for fault isolation and self-healing of a non-channel protection distribution line, including at least two distribution lines. The ends of adjacent two distribution lines are connected by a tie switch. A plurality of sectional 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 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 sectional switch.

[0051] Further, the tie switch has a function of automatically closing when one side loses voltage. When the two distribution lines on both sides are operating normally, the tie switch is open.

[0052] Further, the operation mode of the distribution line is single-source radial.

[0053] Further, 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 a set forward threshold to prevent equipment damage caused by overload or fault of the distribution line. The reverse overcurrent protection module is used to monitor and judge whether the current flows reversely. When a fault occurs, the reverse flow of the current causes damage to the equipment. The accelerated low-voltage protection module is used to protect against low voltage. When the voltage at the sectional switch drops to the low-voltage threshold, the protection action is quickly triggered to cut off the line.

[0054] In this embodiment, the first non-channel protection device on the power supply side of each distribution line can be arranged inside the substation, and this non-channel protection device can be a three-stage overcurrent protection device.

[0055] In this embodiment, when there is no fault in the distribution network, the sectional switch is in the closed state, and the non-channel protection device at the sectional switch is not activated either. When a fault occurs in the distribution network, the non-channel protection device is activated to control the corresponding sectional switch to open and isolate the fault.

[0056] The working states of the tie switch include the closed state and the open state. The adjacent two distribution lines operate in a single - source radial manner. When the distribution network is operating normally, the tie switch is in the open state. When the tie switch is closed, current can flow; when the tie switch is open, current cannot flow.

[0057] When a fault occurs in the distribution line, the non - channel protection device starts, controls the sectionalizing switch adjacent to the fault location to open, and isolates the fault from both ends or the power supply side. After the fault is isolated from both sides, the tie switch will automatically close, thereby restoring power supply to the non - fault area; after the fault is isolated from the power supply side, after the tie switch automatically closes, the reverse over - current protection module of the non - channel protection device operates, thereby achieving fault isolation and power supply restoration.

[0058] In this embodiment, as Figure 1 shown, the ends of distribution line 1 and distribution line 2 are connected by a tie switch. Sectionalizing switches 1, 2, and 3 are sequentially arranged on distribution line 1, and sectionalizing switches 4, 5, and 6 are sequentially arranged on distribution line 2. Each distribution line is divided into four sections of distribution lines. Each section of distribution line is connected to one end of a branch circuit. In the figure, L10, L11, L12, L13, L20, L21, L22, and L23 are all branch circuits, and the other ends of the branch circuits are connected to loads; in the figure, PTU1, PTU2, PTU3, PTU4, PTU5, and PTU6 are all non - channel protection devices, which are respectively installed at sectionalizing switches 1, 2, 3, 4, 5, and 6. The first non - channel protection device on the power supply side of the main distribution line can be arranged inside the substation, and this non - channel protection device can be a three - stage over - current protection device, as Figure 1 shown.

[0059] As Figure 2 shown, the present invention discloses a method for fault isolation and self - healing of a non - channel - protected distribution line. Specifically, it further includes the following steps:

[0060] S100. Use the non - channel protection device to continuously obtain the three - phase current and three - phase voltage at the corresponding sectionalizing switch.

[0061] In this embodiment, the non - channel protection device measures the three - phase current and three - phase voltage at the sectionalizing switch corresponding to it through current transformers and voltage transformers arranged on the distribution line.

[0062] S200. Determine the fault type and fault location according to the changes in the three - phase current and three - phase voltage.

[0063] Further, the S200 includes the following specific steps:

[0064] S210. Determine that the fault type is a two-phase short circuit based on the increase of any two-phase currents in the three-phase current and the decrease of the same two-phase voltages.

[0065] 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.

[0066] S220. Determine that the fault type is a three-phase short circuit based on the increase of the currents in all three phases of the three-phase current; when the fault type is a three-phase short circuit, determine the fault location according to the time difference coordination to ensure selectivity. In this embodiment, using the time difference to determine the fault location is a prior art.

[0067] In this embodiment, the three-phase current includes the currents of phase A, phase B, and phase C, and the three-phase voltage includes the voltages of phase A, phase B, and phase C; when the following phenomena occur: (1) the current of phase A increases, the current of phase B increases, the voltage of phase A decreases, and the voltage of phase B decreases, or (2) the current of phase A increases, the current of phase C increases, the voltage of phase A decreases, and the voltage of phase C decreases, or (3) the current of phase B increases, the current of phase C increases, the voltage of phase B decreases, and the voltage of phase C decreases, etc., it can be determined that a two-phase short circuit has occurred.

[0068] When the fault type is determined to be a two-phase short circuit, obtain the positive-sequence power direction, and determine whether the power flow is forward (from the power source side to the load side) or reverse (the direction of the fault current caused by the fault) according to the positive-sequence power direction, and then determine the working state of the non-channel protection device, 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 power flow direction, the non-channel protection device is for forward overcurrent protection. At this time, the overcurrent protection will trigger corresponding protection actions according to the magnitude of the fault current to 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 power flow reverses, the non-channel protection device will start reverse overcurrent protection to prevent the reverse current caused by the fault in the system from causing harm to the equipment or system.

[0069] When the fault type is determined to be a two-phase short circuit, obtain the negative-sequence power direction, and determine whether the fault is forward or reverse according to the negative-sequence power direction, so as to determine the specific location of the fault. If the negative-sequence power exists and the direction is clear, the reverse or forward 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 one end, it means that the fault may occur on the line at that end.

[0070] When the currents in all three phases of the three-phase current increase, it indicates that the fault type is a three-phase short circuit. In this embodiment, when the currents of phase A, phase B, and phase C all increase, it indicates that a three-phase short circuit has occurred.

[0071] S300. Control the operating state of the sectionalizing switch adjacent to the fault location according to the fault type and fault location, and select to isolate the fault from both sides or from the power supply side according to the operating state of the sectionalizing switch.

[0072] Further, the S300 includes the following specific steps:

[0073] S310. If isolating the fault from both sides, the tie switch automatically closes to restore power supply to the non-fault area.

[0074] Further, the S310 is specifically:

[0075] S311. Based on the fault type being a two-phase short circuit and the fault location being between two sectionalizing switches, after an interval of the first preset time, control the sectionalizing switch adjacent to the fault location and on the power supply side to disconnect, and then after an interval of the second preset time, control the sectionalizing switch adjacent to the fault location and on the load side to disconnect, isolating the fault from both sides; after the sectionalizing switch on the load side disconnects, after an interval of the third preset time, the tie switch automatically closes to restore power supply to the non-fault area.

[0076] In this embodiment, when the fault type is a two-phase short circuit and the fault location is between two sectionalizing switches, first, after an interval of the first preset time, start the forward over-current module of the non-channel protection device adjacent to the fault location and on the power supply side. The non-channel protection device on the power supply side performs forward over-current protection (Over-Current, OC) to control the corresponding sectionalizing switch to disconnect; then, after the second preset time, start the accelerated low-voltage module of the non-channel protection device adjacent to the fault location and on the load side. The non-channel protection device on the load side performs accelerated directional under-voltage protection (Accelerated Directional Under-Voltage, ADUV) to control the corresponding sectionalizing switch to disconnect. By starting the two non-channel protection devices adjacent to the fault location, the fault is quickly and accurately isolated from both sides; finally, since the tie switch has the function of automatic closing 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 tie switch automatically closes after the third preset time, enabling another distribution line to supply power to the distribution line where the fault occurs and restoring power supply 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 stepped time limit coordination principle, and the time difference is 0.1 s. The third preset time can be 10 s.

[0077] S312. Based on the fault type being a two-phase short circuit and the fault location being between the sectionalizing switch and the tie switch, after an interval of the fifth preset time, control the sectionalizing switch to disconnect, isolating the fault from both sides.

[0078] In this embodiment, when the fault type is a two-phase short circuit and the fault location is between the sectionalizing switch and the tie switch, after an interval of the fifth preset time, the forward overcurrent module of the non-channel protection device is started, and the non-channel protection device performs forward overcurrent protection to control the corresponding sectionalizing switch to open, so as to isolate the fault from both sides and restore power supply to the non-fault area.

[0079] S313. Based on the fault type being a three-phase short circuit and the fault location being between the sectionalizing switch and the tie switch, after an interval of the fifth preset time, control the sectionalizing switch to open, and after an interval of the third preset time, the tie switch automatically closes; after the tie switch closes, after an interval of the sixth preset time, control the tie switch to open to isolate the fault from both sides.

[0080] In this embodiment, when the fault type is a three-phase short circuit and the fault location is between the sectionalizing switch and the tie switch, first, after an interval of the fifth preset time, start the forward overcurrent module of the non-channel protection device, and the non-channel protection device performs forward overcurrent protection to control the corresponding sectionalizing switch to open; then, when the tie switch detects a loss of voltage on one side, after an interval of the third preset time, the tie switch automatically closes; finally, after an interval of the sixth preset time, control the tie switch to open and perform forward overcurrent protection to isolate the fault from both ends.

[0081] S320. If the fault is isolated from the power supply side, after the tie switch automatically closes, the non-channel protection device performs a reverse overcurrent operation to isolate the fault and restore power supply.

[0082] Further, S320 is specifically:

[0083] S321. Based on the fault type being a three-phase short circuit and the fault location being between two sectionalizing switches, after an interval of the first preset time, control the sectionalizing switch adjacent to the fault location and on the power supply side to open to isolate the fault from the power supply side; after the sectionalizing switch on the power supply side opens, after an interval of the third preset time, the tie switch automatically closes; after the tie switch closes, after an interval of the fourth preset time, control the sectionalizing switch adjacent to the fault location and on the load side to open to isolate the fault and restore power supply.

[0084] In this embodiment, when the fault is a three-phase short circuit and the fault location is between two sectionalizing switches, first, after an interval of the first preset time, the forward overcurrent module of the non-channel protection device adjacent to the fault location and on the power supply side is started, and the corresponding sectionalizing switch is controlled to disconnect. The non-channel protection device on the power supply side performs forward overcurrent protection to isolate the fault from the power supply side. Then, when the tie switch detects a loss of voltage on one side, the tie switch automatically closes after an interval of the third preset time. Finally, after an interval of the fourth preset time, the reverse overcurrent protection module of the non-channel protection device adjacent to the fault location and on the load side is started. The non-channel protection device on the load side performs reverse overcurrent protection, controls the corresponding sectionalizing switch to disconnect, isolates the fault from both ends, and restores power supply to the non-fault area.

[0085] S322. Based on the fault type being a two-phase short circuit and the accelerating low-voltage protection module of the non-channel protection device adjacent to the fault location and on the load side malfunctioning, after an interval of the first preset time, control the sectionalizing switch adjacent to the fault location and on the power supply side to disconnect, isolating the fault from the power supply side. After the sectionalizing switch on the power supply side disconnects, the tie switch automatically closes after an interval of the third preset time. After the tie switch closes, after an interval of the fourth preset time, control the sectionalizing switch adjacent to the fault location and on the load side to disconnect to isolate the fault and restore power supply.

[0086] In this embodiment, when the fault is a two-phase short circuit and the accelerating low-voltage protection module of the non-channel protection device adjacent to the fault location and on the load side malfunctions, first, after an interval of the first preset time, the forward overcurrent module of the non-channel protection device adjacent to the fault location and on the power supply side is started, and the corresponding sectionalizing switch is controlled to disconnect. The non-channel protection device on the power supply side performs forward overcurrent protection to isolate the fault from the power supply side. Then, when the tie switch detects a loss of voltage on one side, the tie switch automatically closes after an interval of the third preset time. Finally, after an interval of the fourth preset time, the reverse overcurrent protection module of the non-channel protection device adjacent to the fault location and on the load side is started. The non-channel protection device on the load side performs reverse overcurrent protection, controls the corresponding sectionalizing switch to disconnect, and realizes isolating the fault from both ends and restoring power supply to the non-fault area when the accelerating low-voltage protection of the non-channel protection device on the load side refuses to operate due to various reasons (such as too large transition resistance).

[0087] As Figure 1 shown, in this embodiment, the preset time values related to the in-station protection, non-channel protection device, and tie switch are set according to the stepped time limit coordination principle, and the time step is 0.1 s. Figure 1The arrow direction in the figure indicates the forward or reverse current direction. The time setting value of the non-channel protection device for in-station protection is set to 0.8 s. The time setting value of the forward overcurrent protection (forward OC) of the non-channel protection devices PTU1 and PTU4 is 0.7 s, the time setting value of the reverse overcurrent protection (reverse OC) is 0.1 s, and the time setting value of the accelerated low-voltage protection (ADUV) is 0.8 s+. In this embodiment, 0.8 s+ means that the minimum time setting value of ADUV is 0.8 s, and the time setting value of ADUV will be adjusted according to the actual situation of the distribution line, maintaining the minimum time setting value or extending the time setting value; the time setting value of the forward overcurrent protection of the non-channel protection devices PTU2 and PTU5 is 0.6 s, the time setting value of the reverse overcurrent protection is 0.2 s, and the time setting value of the accelerated low-voltage protection is 0.7 s+; the time setting value of the forward overcurrent protection of the non-channel protection devices PTU3 and PTU6 is 0.5 s, the time setting value of the reverse overcurrent protection is 0.3 s, and the time setting value of the accelerated low-voltage protection is 0.6 s+; the time setting values of the forward overcurrent protection and the reverse overcurrent protection of the tie switch are both 0.4 s.

[0088] As shown in Fig. 3(a), the fault type and fault location satisfy S311. The first preset time is 0.8 s, the second preset time is 0.8 s, and the third preset time is 10 s. When a two-phase short-circuit fault occurs between the in-station switch of the substation and the first sectionalizing switch, taking Fig. 3(a) as an example, a two-phase short-circuit fault occurs near the branch circuit L10 in the distribution line 1. After 0.8 s of detecting a fault in the main distribution line, the in-station protection is activated. The in-station protection performs overcurrent protection. Then, after 0.8 s, the accelerated low-voltage protection module of the non-channel protection device PTU1 is activated, and the sectionalizing switch 1 corresponding to PTU1 is controlled to disconnect, so as to isolate 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 10 s to restore power supply to the non-fault area.

[0089] As shown in Figure 3(b), when the fault type and fault location satisfy S321 or S322, the first preset time is 0.8 s, the third preset time is 10 s, and the fourth preset time is 0.1 s. Taking Figure 3(b) as an example, when a three-phase short-circuit fault occurs between the in-station switch and the first sectionalizing switch in the substation, or a two-phase short-circuit fault occurs but the accelerating low-voltage protection module of the non-channel protection device corresponding to the first sectionalizing switch fails, when a three-phase short-circuit fault appears near the branch circuit L10 in the distribution line 1, or a two-phase short-circuit fault appears near the branch circuit L10 in the distribution line 1 but the accelerating low-voltage protection module of the non-channel protection device PTU1 fails, the in-station protection starts after 0.8 s of detecting the fault on line 1 and performs over-current protection. Then, 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 10 s. Finally, after 0.1 s, the reverse over-current protection module of the non-channel protection device PTU1 is turned on, controlling the sectionalizing switch 1 corresponding to PTU1 to disconnect, and the non-channel protection device PTU1 performs reverse over-current protection, realizing the isolation of the fault from both ends and restoring power supply to the non-faulty area.

[0090] As shown in Figure 4(a), when the fault type and fault location satisfy S311, the first preset time is 0.7 s, the second preset time is 0.7 s, and the third preset time is 10 s. Taking Figure 4(a) as an example, when a two-phase short-circuit fault occurs between the first sectionalizing switch and the second sectionalizing switch on the distribution line, when a two-phase short-circuit fault appears near the branch circuit L11 in the distribution line 1, after 0.7 s of detecting the fault on line 1, the forward over-current protection module of the non-channel protection device PTU1 is turned on, controlling the sectionalizing switch 1 corresponding to PTU1 to disconnect, and the non-channel protection device PTU1 performs forward over-current protection. Then, after 0.7 s, the accelerating low-voltage protection module in the non-channel protection device PTU2 is turned on, controlling the sectionalizing switch 2 corresponding to PTU2 to disconnect, 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 10 s to restore power supply to the non-faulty area.

[0091] As shown in Figure 4(b), the fault type and fault location satisfy S321 or S322, the first preset time is 0.7 s, the third preset time is 10 s, and the fourth preset time is 0.2 s. When a three-phase short-circuit fault occurs between the first sectionalizing switch and the second sectionalizing switch on the distribution line, or a two-phase short-circuit fault occurs but the accelerating low-voltage protection module of the non-channel protection device corresponding to the second sectionalizing switch fails, taking Figure 4(b) as an example for illustration. When a three-phase short-circuit fault appears near the branch circuit L11 in the distribution line 1, or a two-phase short-circuit fault appears near the branch circuit L11 in the distribution line 1 but the accelerating low-voltage protection module of the non-channel protection device PTU2 fails, after 0.7 s of detecting the fault on line 1, the forward over-current protection module of the non-channel protection device PTU1 is turned on, controlling the sectionalizing switch 1 corresponding to PTU1 to disconnect, and the non-channel protection device PTU1 performs forward over-current protection. Then, 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 10 s. Finally, after 0.2 s, the reverse over-current protection module of the non-channel protection device PTU2 is turned on, controlling the sectionalizing switch 2 corresponding to PTU2 to disconnect, and the non-channel protection device PTU2 performs reverse over-current protection, realizing the isolation of the fault from both ends and restoring power supply to the non-faulty area.

[0092] As shown in Figure 5(a), the fault type and fault location satisfy S311, the first preset time is 0.6 s, the second preset time is 0.6 s, and the third preset time is 10 s. When a two-phase short-circuit fault occurs between the second sectionalizing switch and the third sectionalizing switch on the distribution line, taking Figure 5(a) as an example for illustration. When a two-phase short-circuit fault appears near the branch circuit L12 in the distribution line 1, after 0.6 s of detecting the fault on line 1, the forward over-current protection module of the non-channel protection device PTU2 is turned on, controlling the sectionalizing switch 2 corresponding to PTU2 to disconnect, and the non-channel protection device PTU2 performs forward over-current protection. Then, after 0.6 s, the accelerating low-voltage protection module of the non-channel protection device PTU3 is turned on, controlling the sectionalizing switch 3 corresponding to PTU3 to disconnect, 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 10 s to restore power supply to the non-faulty area.

[0093] As shown in Fig. 5(b), when the fault type and fault location satisfy S321 or S322, the first preset time is 0.6 s, the third preset time is 10 s, and the fourth preset time is 0.3 s. Taking a three-phase short-circuit fault occurring between the second sectionalizing switch and the third sectionalizing switch on the distribution line, or a two-phase short-circuit fault occurring but the accelerating low-voltage protection module of the non-channel protection device corresponding to the third sectionalizing switch fails as an example, as shown in Fig. 5(b), when a three-phase short-circuit fault appears near the branch circuit L12 in the distribution line 1, or a two-phase short-circuit fault appears near the branch circuit L12 in the line 1 of the distribution line but the accelerating low-voltage protection module of the non-channel protection device PTU3 fails, after 0.6 s from detecting the fault on line 1, the forward over-current protection module of the non-channel protection device PTU2 is turned on, controlling the sectionalizing switch 2 corresponding to PTU2 to disconnect, and the non-channel protection device PTU2 performs forward over-current protection. Then, 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 10 s. Finally, after 0.3 s, the reverse over-current protection module of the non-channel protection device PTU3 is turned on, controlling the sectionalizing switch 3 corresponding to PTU3 to disconnect, and the non-channel protection device PTU3 performs reverse over-current protection, achieving the isolation of the fault from both ends and restoring power supply to the non-fault area.

[0094] As shown in Fig. 6(a), when the fault type and fault location satisfy S312, the fifth preset time is 0.5 s. Taking a two-phase short-circuit fault occurring between the third sectionalizing switch and the tie switch on the distribution line as an example, as shown in Fig. 6(a), when a two-phase short-circuit fault appears near the branch circuit L13 in the distribution line 1, after 0.5 s from detecting the fault on line 1, the forward over-current protection module of the non-channel protection device PTU3 is turned on, controlling the sectionalizing switch 3 corresponding to PTU3 to disconnect, and the non-channel protection device PTU3 performs forward over-current protection, thus achieving the isolation of the fault from both ends.

[0095] As shown in Fig. 6(b), when the fault type and fault location satisfy S313, the third preset time is 10 s, the fifth preset time is 0.5 s, and the sixth preset time is 0.4 s. Taking a three-phase short-circuit fault occurring between the third sectionalizing switch and the tie switch on the distribution line as an example, as shown in Fig. 6(b), when a three-phase short-circuit fault appears near the branch circuit L13 in the distribution line 1, after 0.5 s from detecting the fault on line 1, the forward over-current protection module of the non-channel protection device PTU3 is turned on, controlling the sectionalizing switch 3 corresponding to PTU3 to disconnect, and the non-channel protection device PTU3 performs forward over-current protection. Then, 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 10 s. Finally, after 0.4 s, the tie switch disconnects and performs forward over-current protection. Thus, the isolation of the fault from both ends is achieved.

[0096] In this embodiment, the three-phase current and three-phase voltage at the sectionalizing switch connected to the non-channel protection device are first obtained in real time by the non-channel protection device, and then the changes in the three-phase current and three-phase voltage are analyzed. When the current and voltage mutate, it indicates that a fault has occurred near the sectionalizing switch, and then the type of the fault is determined. Finally, according to the location of the fault and the type of the fault, the working state of the sectionalizing switch adjacent to the fault location is controlled, so as to realize isolating the fault from both sides or isolating the fault from the power supply side and restoring the power supply of the non-fault area. This embodiment does not rely on communication, does not require the construction of a master station and a channel, effectively reduces the investment cost, reduces the dependence on communication, and at the same time, the switches upstream and downstream of the fault point only need to operate once to accurately isolate the fault point, can quickly restore the power supply of the non-fault section, and improves the power supply reliability of the distribution line.

[0097] Embodiment Two

[0098] As Figure 7 shown, the present invention also discloses a non-channel protection-based distribution line fault isolation and self-healing system, including at least two distribution lines. The ends of two adjacent distribution lines are connected by a tie switch. A plurality of sectionalizing switches are arranged on the distribution line, dividing a single distribution line into multiple sections of distribution lines. Each section of 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 sectionalizing switch.

[0099] Furthermore, the tie switch has a function of automatically closing when one side loses voltage. When the two distribution lines are operating normally, the tie switch is open.

[0100] Furthermore, the operation mode of the distribution line is single-source radial.

[0101] Furthermore, the non-channel protection device includes a forward overcurrent protection module, a reverse overcurrent protection module, and an accelerating low voltage protection module. The forward overcurrent protection module is used to detect whether the current exceeds the set forward threshold to prevent equipment damage caused by overload or fault of the distribution line. The reverse overcurrent protection module is used to monitor and judge whether the current flows reversely. When a fault occurs, the reverse flow of the current causes damage to the equipment. The accelerating low voltage protection module is used to protect under the condition of too low voltage. When the voltage at the sectionalizing switch drops to the low voltage threshold, the protection action is quickly triggered to cut off the line.

[0102] In this embodiment, the first non-channel protection device at the power supply side of each distribution line can be arranged inside the substation, and this non-channel protection device can be a three-stage overcurrent protection device.

[0103] In this embodiment, when there is no fault in the distribution network, the sectionalizing switch is in the closed state, and the non-channel protection device at the sectionalizing switch is not activated either. When a fault occurs in the distribution network, the non-channel protection device is activated to control the corresponding sectionalizing switch to open and isolate the fault.

[0104] The working states of the tie switch include the closed state and the open state. The adjacent two distribution lines operate in a single-source radial manner. When the distribution network is operating normally, the tie switch is in the open state. When the tie switch is closed, current can flow. When the tie switch is open, current cannot flow.

[0105] When a fault occurs in the distribution line, the non-channel protection device is activated to control the sectionalizing switch adjacent to the fault location to open, isolating the fault from both ends or the power supply side. After the fault is isolated from both sides, the tie switch will automatically close, thus restoring power supply to the non-fault area. After the fault is isolated from the power supply side, after the tie switch automatically closes, the reverse overcurrent protection module of the non-channel protection device operates, thus achieving fault isolation and power supply restoration.

[0106] The present invention discloses a distribution line fault isolation and self-healing system with non-channel protection, further including an acquisition module, a determination module, and a control module.

[0107] The acquisition module is used to utilize the non-channel protection device to acquire the three-phase current and three-phase voltage at the corresponding sectionalizing switch in real time.

[0108] In this embodiment, the non-channel protection device measures the three-phase current and three-phase voltage at the sectionalizing switch corresponding to the non-channel protection device through current transformers and voltage transformers arranged on the distribution line.

[0109] The determination module is used to determine the fault type and fault location according to the changes in the three-phase current and three-phase voltage.

[0110] Further, the determination module includes a two-phase short-circuit unit and a three-phase short-circuit unit.

[0111] The two-phase short-circuit unit is used to determine that the fault type is two-phase short-circuit based on any two-phase currents in the three-phase current increasing and the same two-phase voltages decreasing. Based on the fault type being two-phase short-circuit, according to the positive-sequence power direction, determine whether the power flow is forward or reverse to determine the working state of the non-channel protection device. Based on the fault type being two-phase short-circuit, according to the negative-sequence power direction, determine whether the fault is forward or reverse to determine the fault location.

[0112] The three-phase short-circuit unit is used to determine that the fault type is three-phase short-circuit based on all three-phase currents in the three-phase current increasing. Based on the fault type being three-phase short-circuit, determine the fault location according to the time difference coordination to ensure selectivity. In this embodiment, using the time difference to determine the fault location is a prior art.

[0113] In this embodiment, the three-phase current includes the A-phase, B-phase, and C-phase currents, and the three-phase voltage includes the A-phase, B-phase, and C-phase voltages; when the following phenomena occur: (1) the A-phase current increases, the B-phase current increases, the A-phase voltage decreases, and the B-phase voltage decreases, or (2) the A-phase current increases, the C-phase current increases, the A-phase voltage decreases, and the C-phase voltage decreases, or (3) the B-phase current increases, the C-phase current increases, the B-phase voltage decreases, and the C-phase voltage decreases, etc., it can be determined that a two-phase short circuit has occurred.

[0114] When the fault type is determined to be a two-phase short circuit, the positive-sequence power direction is obtained, and based on the positive-sequence power direction, it is determined whether the power flow is forward (from the power supply side to the load side) or reverse (the direction of the fault current caused by the fault), and then the operating 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 power flow direction, the non-channel protection device performs forward overcurrent protection. At this time, the overcurrent protection will trigger corresponding protection actions according to the magnitude of the fault current to 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 power flow reverses, the non-channel protection device will start reverse overcurrent protection to prevent the reverse current caused by the fault in the system from causing harm to the equipment or system.

[0115] When the fault type is determined to be a two-phase short circuit, the negative-sequence power direction is obtained, and based on the negative-sequence power direction, it is determined whether the fault is forward or reverse, so as to determine the specific location of the fault. If the negative-sequence power exists and the direction is clear, the reverse or forward 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.

[0116] When the currents of all three phases in the three-phase current increase, it indicates that the fault type is a three-phase short circuit. In this embodiment, when the A-phase current, B-phase current, and C-phase current all increase, it indicates that a three-phase short circuit has occurred.

[0117] The control module is used to control the operating state of the sectional switch adjacent to the fault location according to the fault type and fault location, and select to isolate the fault from both sides or isolate the fault from the power supply side according to the operating state of the sectional switch;

[0118] Furthermore, the control module includes a two-side isolation unit and a power supply side isolation unit:

[0119] The two-side isolation unit is used to judge that if the fault is isolated from both sides, the tie switch automatically closes to restore power supply to the non-fault area.

[0120] Furthermore, the two-side isolation unit is specifically:

[0121] Based on the fault type being a two-phase short circuit and the fault location being between two sectionalizing switches, after an interval of the first preset time, control the sectionalizing switch adjacent to the fault location and on the power supply side to open, and then after an interval of the second preset time, control the sectionalizing switch adjacent to the fault location and on the load side to open, isolating the fault from both sides; after the sectionalizing switch on the load side opens, the tie switch automatically closes after an interval of the third preset time to restore power supply to the non-fault area.

[0122] In this embodiment, when the fault type is a two-phase short circuit and the fault location is between two sectionalizing switches, first, after an interval of the first preset time, start the forward over-current module of the non-channel protection device adjacent to the fault location and on the power supply side. The non-channel protection device on the power supply side performs forward over-current protection (Over-Current, OC) to control the corresponding sectionalizing switch to open; then, after an interval of the second preset time, start the accelerated under-voltage module of the non-channel protection device adjacent to the fault location and on the load side. The non-channel protection device on the load side performs accelerated under-voltage protection (Accelerated Directional Under-Voltage, ADUV) to control the corresponding sectionalizing switch to open. By starting the two non-channel protection devices adjacent to the fault location, the fault can be quickly and accurately isolated from both sides; finally, since the tie 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 tie switch automatically closes after an interval of the third preset time, enabling another distribution line to supply power to the distribution line where the fault occurs and restoring power supply 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 stepped time limit cooperation principle, with a time difference of 0.1 s, and the third preset time can be 10 s.

[0123] Based on the fault type being a two-phase short circuit and the fault location being between a sectionalizing switch and a tie switch, after an interval of the fifth preset time, control the sectionalizing switch to open to isolate the fault from both sides.

[0124] In this embodiment, when the fault type is a two-phase short circuit and the fault location is between a sectionalizing switch and a tie switch, after an interval of the fifth preset time, start the forward over-current module of the non-channel protection device. The non-channel protection device performs forward over-current protection to control the corresponding sectionalizing switch to open, which can isolate the fault from both sides and restore power supply to the non-fault area.

[0125] Based on the fault type being a three-phase short circuit and the fault location being between a sectionalizing switch and a tie switch, after an interval of the fifth preset time, control the sectionalizing switch to open, and after an interval of the third preset time, the tie switch automatically closes; after the tie switch closes, after an interval of the sixth preset time, control the tie switch to open to isolate the fault from both sides.

[0126] In this embodiment, when the fault type is three-phase short circuit and the fault location is between the sectionalizing switch and the tie switch, first, after an interval of the fifth preset time, the forward overcurrent module of the non-channel protection device is started, and the non-channel protection device performs forward overcurrent protection to control the corresponding sectionalizing switch to open; then, when the tie switch detects a loss of voltage on one side, the tie switch automatically closes after an interval of the third preset time; finally, after an interval of the sixth preset time, the tie switch is controlled to open to perform forward overcurrent protection, so as to isolate the fault from both ends.

[0127] The power supply side isolation unit is used to judge that if the fault is isolated from the power supply side, after the tie switch automatically closes, the non-channel protection device performs reverse overcurrent operation to isolate the fault and restore power supply.

[0128] Further, the power supply side isolation unit is specifically:

[0129] Based on the fault type being three-phase short circuit and the fault location being between two sectionalizing switches, after an interval of the first preset time, the sectionalizing switch adjacent to the fault location and on the power supply side is controlled to open to isolate the fault from the power supply side; after the sectionalizing switch on the power supply side opens, the tie switch automatically closes after an interval of the third preset time; after the tie switch closes, after an interval of the fourth preset time, the sectionalizing switch adjacent to the fault location and on the load side is controlled to open to isolate the fault and restore power supply.

[0130] In this embodiment, when the fault is three-phase short circuit and the fault location is between two sectionalizing switches, first, after an interval of the first preset time, the forward overcurrent module of the non-channel protection device adjacent to the fault location and on the power supply side is started, and the corresponding sectionalizing switch is controlled to open. The non-channel protection device on the power supply side performs forward overcurrent protection to isolate the fault from the power supply side; then, when the tie switch detects a loss of voltage on one side, the tie switch automatically closes after an interval of the third preset time; finally, after an interval of the fourth preset time, the reverse overcurrent protection module of the non-channel protection device adjacent to the fault location and on the load side is started, and the non-channel protection device on the load side performs reverse overcurrent protection to control the corresponding sectionalizing switch to open, so as to isolate the fault from both ends and restore power supply to the non-fault area.

[0131] Based on the fault type being two-phase short circuit and the accelerating low-voltage protection module of the non-channel protection device adjacent to the fault location and on the load side failing, after an interval of the first preset time, the sectionalizing switch adjacent to the fault location and on the power supply side is controlled to open to isolate the fault from the power supply side; after the sectionalizing switch on the power supply side opens, the tie switch automatically closes after an interval of the third preset time; after the tie switch closes, after an interval of the fourth preset time, the sectionalizing switch adjacent to the fault location and on the load side is controlled to open to isolate the fault and restore power supply.

[0132] In this embodiment, when the fault is a two-phase short circuit and the accelerating low-voltage protection module of the non-channel protection device on the load side adjacent to the fault location fails, first, after an interval of the first preset time, the forward over-current module of the non-channel protection device on the power side adjacent to the fault location is started, and the corresponding sectional switch is controlled to disconnect. The non-channel protection device on the power side performs forward over-current protection to isolate the fault from the power side. Then, when the tie switch detects a loss of voltage on one side, the tie switch automatically closes after an interval of the third preset time. Finally, after an interval of the fourth preset time, the reverse over-current protection module of the non-channel protection device on the load side adjacent to the fault location is started, and the non-channel protection device on the load side performs reverse over-current protection to control the corresponding sectional switch to disconnect, achieving the isolation of the fault from both ends when the accelerating low-voltage protection of the non-channel protection device on the load side fails due to various reasons (such as too large transition resistance), and restoring power supply to the non-fault area.

[0133] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate 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; 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; S220, determining that the fault type is a three-phase short circuit based on that the currents of the three phases of the three-phase current are all increased; S300, according to the fault type and the fault location, controlling the working state of the section switch adjacent to the fault location, and according to the working state of the section switch, selecting to isolate the fault from the power supply side; If the fault is isolated from the power supply side, after the tie switch is automatically closed, the non-channel protection device performs reverse overcurrent action to isolate the fault and restore power supply; 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 adjacent to the fault location and located on the load side fails, the forward overcurrent module of the non-channel protection device adjacent to the fault location and located on the power supply side is started after a first preset time interval, and the corresponding section switch is controlled to disconnect, thereby isolating the fault from the power supply side; after a third preset time interval, the connecting switch is automatically closed, and after a fourth preset time interval, 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 corresponding section switch is controlled to disconnect, thereby restoring power supply to the non-fault area.

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: When the fault type is 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 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; When the fault type is a three-phase short circuit, the fault location is determined based on the time difference coordination.

4. A non-channel protection distribution line fault isolation and self-healing method according to claim 1, 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.

5. 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; Based on the increase of any two-phase current among the three-phase currents and the decrease of the voltage of the same two phases, the fault type is determined to be a two-phase short circuit; Based on the fact that the currents of the three phases of the three-phase current all increase, it is determined that the fault type is a three-phase short circuit; A control module, 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 select to isolate the fault from the power supply side according to the working state of the section switch; If the fault is isolated from the power supply side, after the tie switch is automatically closed, the non-channel protection device performs reverse overcurrent action to isolate the fault and restore power supply; 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, the forward overcurrent module of the non-channel protection device located on the power supply side adjacent to the fault location is started after a first preset time interval, and the corresponding section switch is controlled to be disconnected to isolate the fault from the power supply side; After the third preset time, the connecting switch is automatically closed. After the 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 corresponding section switch is controlled to disconnect, thereby restoring power supply to the non-fault area.

6. A non-channel protection distribution line fault isolation and self-healing system according to claim 5, 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.

7. A non-channel protection distribution line fault isolation and self-healing system according to claim 5, characterized in that: The determination module comprises: When the fault type is 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 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; When the fault type is a three-phase short circuit, the fault location is determined based on the time difference coordination.

Images