Low-voltage transformer area short-circuit fault accurate positioning method, short-circuit fault positioning terminal and low-voltage switch

Abstract

The invention relates to a low-voltage transformer area short-circuit fault accurate positioning method, a short-circuit fault positioning terminal and a low-voltage switch, and belongs to the field of power system short-circuit fault positioning. The method comprises the following steps: when a short-circuit fault tripping message sent by only one low-voltage switch is received, determining that a short-circuit fault occurs on a line between the low-voltage switch sending the short-circuit fault tripping message and the low-voltage switch of the next level; after a short-circuit fault tripping message sent by one low-voltage switch is received, a short-circuit fault indication message which is sent by other low-voltage switches on the downstream of a line where the low-voltage switch is located and sent when a short-circuit fault condition is met and a power failure occurs is also received. And if yes, determining that the short-circuit fault occurs on a line between the last-stage low-voltage switch sending the short-circuit fault indication message and the next-stage low-voltage switch. By comprehensively analyzing different message conditions and combining a topological structure, the short-circuit fault can be automatically and accurately positioned between two adjacent switches before and after.

Description

Technical Field

[0001] The invention relates to a method for accurately locating a short-circuit fault in a low-voltage station area, a short-circuit fault locating terminal and a low-voltage switch, and belongs to the field of short-circuit fault locating in a power system. Background Art

[0002] The topological structure of low-voltage stations in most areas of China is complex. Figure 1 , Figure 1 The following is a structural diagram of an existing low-voltage distribution system. Figure 1 As shown, the low-voltage substation outputs electricity from the transformer, passes through low-voltage switches, distribution rooms, branch boxes, and lines at various levels, and distributes it radially to end users for use.

[0003] When a short circuit occurs, the low-voltage switch is used for protection and removal to meet the safety and stability requirements of the power system. Due to the simple configuration of the low-voltage switch protection, although it is designed according to the requirements of relay protection such as rapidity, selectivity, and sensitivity, it still cannot meet the protection needs of the low-voltage area. Refusal to operate, false operation, and overstepping often occur. When a short circuit occurs, it is difficult to quickly locate the fault range. The traditional method is for the operation and maintenance personnel to check the fault point on site. This method is not only labor-intensive and inefficient, but also prolongs the power outage time and is prone to safety hazards. Summary of the invention

[0004] The purpose of the present invention is to provide a method for accurately locating short-circuit faults in low-voltage distribution areas, a short-circuit fault locating terminal and a low-voltage switch, so as to solve the problem in the prior art that it is difficult to quickly locate the fault range when a short-circuit fault occurs in a low-voltage distribution area.

[0005] To achieve the above object, the solution of the present invention includes:

[0006] A method for accurately locating a short-circuit fault in a low-voltage station area of ​​the present invention comprises:

[0007] When only one short-circuit fault tripping message is received from a low-voltage switch, it is determined that the short-circuit fault occurs on the line between the low-voltage switch that sends the short-circuit fault tripping message and the low-voltage switch at the next level;

[0008] After receiving a short-circuit fault tripping message sent by a low-voltage switch, when short-circuit fault indication messages sent by other low-voltage switches on the downstream of the line where the low-voltage switch is located are also received, it is determined that the short-circuit fault occurs on the line between the last-stage low-voltage switch that sends the short-circuit fault indication message and the low-voltage switch of the next stage;

[0009] When the low-voltage switch fails to deliver power after a short-circuit fault condition is met, the short-circuit fault indication message is sent.

[0010] Further, the short circuit fault condition includes:

[0011] If the sudden change current of the low-voltage switch is greater than or equal to the first preset current and the duration is within a preset time range, it is considered that the short-circuit fault condition is met.

[0012] Furthermore, the first preset current is greater than or equal to 150A; and the preset time range is [0.020s, 3s).

[0013] Furthermore, the low-voltage switch cuts off power for at least 200 milliseconds after the short-circuit fault condition is met, and sends a short-circuit fault indication message.

[0014] A short-circuit fault locating terminal of the present invention determines that the short-circuit fault occurs on the line between the low-voltage switch that sends the short-circuit fault tripping message and the next-level low-voltage switch when the short-circuit fault locating terminal receives a short-circuit fault tripping message sent by only one low-voltage switch;

[0015] After receiving a short-circuit fault tripping message sent by a low-voltage switch, the short-circuit fault locating terminal also receives a short-circuit fault indication message sent by other low-voltage switches downstream of the line where the low-voltage switch is located when the power is cut off after the short-circuit fault conditions are met. It is determined that the short-circuit fault occurs on the line between the last-level low-voltage switch that sends the short-circuit fault indication message and the low-voltage switch at the next level.

[0016] Furthermore, the short-circuit fault condition includes: if the sudden change current of the low-voltage switch is greater than or equal to a first preset current and the duration is within a preset time range, it is considered that the short-circuit fault condition is met.

[0017] A low-voltage switch of the present invention sends a short-circuit fault indication message when the power is cut off after the short-circuit fault condition is met.

[0018] Furthermore, the short-circuit fault condition includes: if the sudden change current of the low-voltage switch is greater than or equal to a first preset current and the duration is within a preset time range, it is considered that the short-circuit fault condition is met.

[0019] Furthermore, the first preset current is greater than or equal to 150A; and the preset time range is [0.020s, 3s).

[0020] Furthermore, the low-voltage switch cuts off power for at least 200 milliseconds after the short-circuit fault condition is met, and sends a short-circuit fault indication message.

[0021] The beneficial effects of the present invention are as follows: as a pioneering invention, the present invention determines that the short-circuit fault occurs on the line between the low-voltage switch that sends the short-circuit fault tripping message and the low-voltage switch at the next level according to the topological structure when only a short-circuit fault tripping message sent by a low-voltage switch is received; after receiving a short-circuit fault tripping message sent by a low-voltage switch, short-circuit fault indication messages sent by other low-voltage switches are also received, and then, according to the topological structure, it is determined that the short-circuit fault occurs on the line between the low-voltage switch at the last level that sends the short-circuit fault indication message and the low-voltage switch at the next level. By comprehensively analyzing different message situations and combining the topological structure, it is possible to automatically and accurately locate the short-circuit fault between the two adjacent switches in front and behind. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an existing low-voltage distribution system;

[0023] Figure 2 It is a flow chart of a method for accurately locating a short-circuit fault in a low-voltage transformer area provided by an embodiment of the present invention;

[0024] Figure 3 It is a structural schematic diagram of a terminal in a low-voltage distribution system provided by an embodiment of the present invention when receiving a fault trip message;

[0025] Figure 4 It is a structural schematic diagram of a terminal in a low-voltage distribution system provided by an embodiment of the present invention when receiving a fault tripping message and two fault indication messages. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0027] The low-voltage switch of the present invention sends a short-circuit fault tripping message to the terminal after the fault trips, and when it is detected that the sudden change current is greater than or equal to the first preset current, it is considered that the fault starting condition is met; when the fault starting condition is met, if the fault time is less than the second preset time and greater than or equal to the first preset time, it is considered that the short-circuit fault condition is met, and a power outage occurs after the short-circuit fault condition is met, and a short-circuit fault indication message is sent to the terminal.

[0028] The terminal monitors the short-circuit fault tripping messages and short-circuit fault indication messages of each low-voltage switch in the low-voltage area in real time. When a short-circuit fault tripping message is received from a low-voltage switch, it is determined that the short-circuit fault occurs on the line between the low-voltage switch that sent the short-circuit fault tripping message and the low-voltage switch of the next level; when a short-circuit fault tripping message is received from a low-voltage switch, and short-circuit fault indication messages are received from other low-voltage switches downstream of the line where the low-voltage switch is located, it is determined that the short-circuit fault occurs on the line between the low-voltage switch at the last level that sent the short-circuit fault indication message and the low-voltage switch of the next level.

[0029] Method Example:

[0030] This embodiment provides a method for accurately locating short-circuit faults in a low-voltage station area.

[0031] The method of the present invention is implemented on a short-circuit fault locating terminal, which may be, for example, a concentrator, an intelligent fusion terminal, etc. The short-circuit fault locating terminal includes a topology identification part and a short-circuit fault information analysis part.

[0032] Among them, the topology identification part can collect the topology identification information reported by the low-voltage switches at all levels in the low-voltage substation, and generate the physical topology relationship of the low-voltage switches in the entire low-voltage substation according to the topology identification information.

[0033] As an optional implementation, the physical topological relationship of the low-voltage switches in the low-voltage area may be stored in the short-circuit fault locating terminal in advance for retrieval when needed.

[0034] This part identifies the front and rear relationship of each low-voltage switch, and combines the fault information during short circuit to locate the short circuit fault between the two adjacent switches.

[0035] The method of the present invention also relies on a low-voltage switch arranged in a low-voltage station area, and the low-voltage switch includes a low-voltage switch topology identification part, a low-voltage switch short-circuit fault trip reporting part and a low-voltage switch short-circuit fault indication part.

[0036] Among them, the low-voltage switch topology identification part can enable the low-voltage switch to participate in the topology identification process and send the topology identification information to the short-circuit fault location terminal.

[0037] This part can help the short-circuit fault location terminal understand the topological relationship between each low-voltage switch and other low-voltage switches.

[0038] Among them, the low-voltage switch short-circuit fault trip reporting part can send a fault trip message to the short-circuit fault locating terminal after the low-voltage switch trips.

[0039] This part can protect the safety of the equipment behind the tripped low-voltage switch. The tripping of the low-voltage switch indicates that a short circuit fault has occurred in the line behind the low-voltage switch.

[0040] Among them, the short-circuit fault indication part of the low-voltage switch can enable the low-voltage switch to send a short-circuit fault indication message to the short-circuit fault locating terminal when the power is cut off after the short-circuit fault condition is met.

[0041] The short circuit fault conditions are:

[0042] When the sudden change current of the low-voltage switch is greater than or equal to the first preset current, it is considered that the fault start condition is met;

[0043] When the fault start condition is met, if the duration of the fault time is within a preset time range, it is considered that the short circuit fault condition is met.

[0044] Among them, the first preset current can be 150A, or other values, etc., which can be selected according to the actual situation, and the present invention does not make any special restrictions on this. The preset time range can be [0.020s, 3s), or other values, etc., which can be selected according to the actual situation, and the present invention does not make any special restrictions on this. The setting of the power outage time can be set according to the actual situation, and the present invention does not make any special restrictions on this. The following example takes the power outage time of at least 200 milliseconds (ms) as an example for exemplary explanation. After the low-voltage switch is powered off, the voltage disappears and the current also disappears.

[0045] This part can enable the low-voltage switch to detect a short-circuit fault before power failure, indicating that the upper-level low-voltage switch of this low-voltage switch has tripped, and the real short-circuit fault occurred after this switch.

[0046] The short-circuit fault location terminal communicates with each low-voltage switch in the low-voltage area through a communication module. The communication module can be a high-speed power line carrier communication (HPLC) module or a dual-mode communication module, etc. The present invention does not make any special limitation on this.

[0047] The communication module has a backup battery, which can maintain communication with the terminal for several times after a power outage.

[0048] Through the communication module, the short-circuit fault locating terminal can receive topology identification information, short-circuit fault tripping messages and short-circuit fault indication messages sent by the low-voltage switch.

[0049] The terminal short-circuit fault information analysis part is a central processor in the short-circuit fault identification, which is used to execute a low-voltage substation short-circuit fault accurate positioning method provided in this embodiment.

[0050] Specifically, please refer to Figure 2 . Figure 2 FIG. 1 is a flow chart of a method for accurately locating a short-circuit fault in a low-voltage transformer area provided by an embodiment of the present invention. Figure 2 As shown, during the operation of the short-circuit fault locating terminal, the short-circuit fault information analysis part of the terminal monitors the short-circuit fault tripping messages and short-circuit fault indication messages sent by each low-voltage switch, and then determines whether only a short-circuit fault tripping message sent by a low-voltage switch is received. If so, according to the topological structure of the low-voltage station area, the short-circuit fault is automatically located between the low-voltage switch that sent the short-circuit fault tripping message and the switch at the next level. If a short-circuit fault tripping message sent by a low-voltage switch is received, and short-circuit fault indication messages sent by other low-voltage switches on the downstream line of the low-voltage switch are also received, then according to the topological structure of the low-voltage station area, the short-circuit fault is automatically located on the line between the low-voltage switch at the last level that sent the short-circuit fault indication message and the low-voltage switch at the next level.

[0051] Combine the following Figure 3 and Figure 4 The following describes how a method for accurately locating short-circuit faults in a low-voltage transformer area provided by an embodiment of the present invention works in practical applications.

[0052] like Figure 3 and Figure 4 As shown, the terminal is set on a busbar of the transformer, and the busbar is connected to the distribution room busbar through a low-voltage switch QF10. A plurality of branch lines are connected in parallel on the distribution room busbar, and each branch line is connected to the distribution room busbar through a low-voltage switch. For example, the first branch line of the distribution room busbar is connected to the distribution room busbar through a low-voltage switch QF11, the second branch line of the distribution room busbar is connected to the distribution room busbar through a low-voltage switch QF12, and the third branch line of the distribution room busbar is connected to the distribution room busbar through a low-voltage switch QF13... and so on.

[0053] Each branch line on the busbar in the distribution room will be connected to the corresponding branch box busbar through the corresponding low-voltage switch. Figure 3 and Figure 4 The following explanations are given by taking the second branch line of the distribution room busbar as an example to connect to the branch box busbar through the low-voltage switch QF20.

[0054] There are multiple branch lines connected in parallel on the branch box bus, and each branch line is connected to the branch box bus through a low-voltage switch. For example, the first branch line of the branch box bus is connected to the branch box bus through a low-voltage switch QF21, the second branch line of the branch box bus is connected to the branch box bus through a low-voltage switch QF22, the third branch line of the branch box bus is connected to the branch box bus through a low-voltage switch QF23... and so on.

[0055] Each branch line on the branch box busbar will be connected to the corresponding other branch box busbars through the corresponding low-voltage switch. Figure 3 and Figure 4 The following examples are used to illustrate the connection of the second branch line of the branch box to the busbars of other branch boxes through the low-voltage switch QF30.

[0056] The second branch line of the branch box is connected to the other branch box bus through the low-voltage switch QF30 is called the second branch box bus.

[0057] There are multiple branch lines connected in parallel on the second branch box bus, and each branch line is connected to the second branch box bus through a low-voltage switch. For example, the first branch line of the second branch box bus is connected to the second branch box bus through a low-voltage switch QF31, the second branch line of the second branch box bus is connected to the second branch box bus through a low-voltage switch QF32, and the third branch line of the second branch box bus is connected to the second branch box bus through a low-voltage switch QF33... and so on.

[0058] Each branch line of the second branch box busbar will be connected to the corresponding user's home for the user to use.

[0059] Figure 3 1 is a schematic diagram of a structure of a terminal in a low-voltage distribution system provided by an embodiment of the present invention when receiving a fault trip message, such as Figure 3 As shown, when the terminal only receives the short-circuit fault tripping message sent by the low-voltage switch QF12, combined with the topological structure, it is located that the short-circuit fault occurs on the line between the low-voltage switch QF12 and the next-level low-voltage switch QF20.

[0060] Figure 4 1 is a schematic diagram of a structure of a terminal in a low-voltage distribution system provided by an embodiment of the present invention when receiving a fault trip message and two fault indication messages, such as Figure 4 As shown, after the terminal receives the short-circuit fault tripping message sent by the low-voltage switch QF12, it receives the short-circuit fault indication message sent by the low-voltage switch QF20, and then receives the short-circuit fault indication message sent by the low-voltage switch QF22, indicating that the low-voltage switch in the low-voltage substation has tripped beyond the level, causing a short-circuit fault. The terminal comprehensively analyzes the short-circuit fault tripping message and the short-circuit fault indication message, and combines the topological structure to conclude that the low-voltage switch QF22 is the last low-voltage switch to send a fault indication message, and the actual short-circuit fault occurs on the line between the low-voltage switch QF22 and the low-voltage switch QF30.

[0061] The embodiment of the present invention provides a method for accurately locating short-circuit faults in a low-voltage substation. When only a short-circuit fault tripping message sent by a low-voltage switch is received, the method determines, based on the topological structure, that the short-circuit fault occurs on the line between the low-voltage switch that sends the short-circuit fault tripping message and the low-voltage switch of the next level; after receiving a short-circuit fault tripping message sent by a low-voltage switch, short-circuit fault indication messages sent by other low-voltage switches are also received. Then, based on the topological structure, it is determined that the short-circuit fault occurs on the line between the low-voltage switch of the last level that sends the short-circuit fault indication message and the low-voltage switch of the next level. By comprehensively analyzing different message situations and combining the topological structure, it is possible to automatically and accurately locate the short-circuit fault between the two adjacent switches in front and behind, reduce the work pressure of the operation and maintenance personnel, reduce the duration of power outages, and thus reduce the occurrence of safety accidents.

[0062] An embodiment of a short-circuit fault locating terminal:

[0063] Regarding the implementation example of the short-circuit fault locating terminal, reference may be made to the related description about the short-circuit fault locating terminal in the aforementioned method for accurately locating short-circuit faults in low-voltage substations, which will not be described in detail here.

[0064] The short-circuit fault locating terminal provided in the embodiment of the present invention can achieve the same beneficial effects as the aforementioned method for accurately locating short-circuit faults in a low-voltage substation area, and will not be described in detail here.

[0065] An embodiment of a low voltage switch:

[0066] Regarding the implementation example of the low-voltage switch, reference may be made to the related description about the low-voltage switch in the aforementioned method for accurately locating a short-circuit fault in a low-voltage station area, which will not be repeated here.

[0067] The low-voltage switch provided by the embodiment of the present invention sends a short-circuit fault indication message, so that the short-circuit fault locating terminal can grasp the real short-circuit fault position. The low-voltage switch provided by the embodiment of the present invention, combined with the short-circuit fault locating terminal in the aforementioned embodiment, can automatically and accurately locate the short-circuit fault interval of the low-voltage station area to reduce the work pressure of the operation and maintenance personnel.

Claims

1. A method for accurately locating short-circuit faults in low-voltage areas, characterized in that: include: When only one short-circuit fault tripping message is received from a low-voltage switch, it is determined that the short-circuit fault occurs on the line between the low-voltage switch that sends the short-circuit fault tripping message and the low-voltage switch at the next level; After receiving a short-circuit fault tripping message sent by a low-voltage switch, when short-circuit fault indication messages sent by other low-voltage switches on the downstream of the line where the low-voltage switch is located are also received, it is determined that the short-circuit fault occurs on the line between the last-stage low-voltage switch that sends the short-circuit fault indication message and the low-voltage switch of the next stage; When the low-voltage switch fails to deliver power after a short-circuit fault condition is met, the short-circuit fault indication message is sent.

2. The method for accurately locating short-circuit faults in low-voltage substations according to claim 1 is characterized in that: The short circuit fault conditions include: If the sudden change current of the low-voltage switch is greater than or equal to the first preset current and the duration is within a preset time range, it is considered that the short-circuit fault condition is met.

3. The method for accurately locating short-circuit faults in low-voltage substations according to claim 2 is characterized in that: The first preset current is greater than or equal to 150A; the preset time range is [0.020s, 3s).

4. The method for accurately locating short-circuit faults in low-voltage substations according to any one of claims 1 to 3, characterized in that: The low-voltage switch cuts off power for at least 200 milliseconds after the short-circuit fault condition is met, and sends the short-circuit fault indication message.

5. A short-circuit fault location terminal, characterized in that: When the short-circuit fault locating terminal receives a short-circuit fault tripping message sent by only one low-voltage switch, it determines that the short-circuit fault occurs on the line between the low-voltage switch that sends the short-circuit fault tripping message and the low-voltage switch at the next level; After receiving a short-circuit fault tripping message sent by a low-voltage switch, the short-circuit fault locating terminal also receives a short-circuit fault indication message sent by other low-voltage switches downstream of the line where the low-voltage switch is located when the power is cut off after the short-circuit fault conditions are met. It is determined that the short-circuit fault occurs on the line between the last-level low-voltage switch that sends the short-circuit fault indication message and the low-voltage switch of the next level.

6. The short-circuit fault location terminal according to claim 5, characterized in that: The short-circuit fault condition includes: if the sudden change current of the low-voltage switch is greater than or equal to the first preset current and the duration is within a preset time range, it is considered that the short-circuit fault condition is met.

7. A low voltage switch, characterized in that: When the low-voltage switch fails to supply power after a short-circuit fault condition is met, a short-circuit fault indication message is sent.

8. The low voltage switch according to claim 7, characterized in that: The short-circuit fault condition includes: if the sudden change current of the low-voltage switch is greater than or equal to the first preset current and the duration is within a preset time range, it is considered that the short-circuit fault condition is met.

9. The low voltage switch according to claim 8, characterized in that: The first preset current is greater than or equal to 150A; the preset time range is [0.020s, 3s).

10. The low voltage switch according to any one of claims 7 to 9, characterized in that: The low-voltage switch cuts off power for at least 200 milliseconds after the short-circuit fault condition is met, and sends the short-circuit fault indication message.

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