Small power supply grounding fault line selection device

Abstract

The utility model relates to a small power source ground fault line selection device, which belongs to the technical field of ground fault line selection, and comprises a plurality of monitoring units, a processing unit and a cut-off unit, the plurality of monitoring units are respectively arranged on each node of each phase of a three-phase circuit and are used for collecting zero sequence current of each node; the processing unit is respectively connected with the plurality of monitoring units, and selects a branch with a grounding fault based on the zero-sequence current of each node so as to realize single-phase grounding fault line selection; the cut-off unit is connected in series to each node of each phase of the three-phase circuit, and the processing unit is connected with the cut-off unit and used for controlling the cut-off unit to act. Each node of the three-phase circuit is provided with the monitoring unit, the zero-sequence current of each node can be collected, the processing unit controls the cut-off unit corresponding to the zero-sequence current transformer to act based on the zero-sequence current of each node, the single-phase earth fault in the power transmission line can be rapidly and accurately positioned, and the cut-off unit controls the cut-off of the fault line.

Description

Technical Field

[0001] The utility model relates to the technical field of grounding fault line selection, and particularly relates to a small power source grounding fault line selection device. Background Technique

[0002] In a power transmission system, the small current grounding system with the neutral point not grounded or grounded through an arc suppression coil is two common grounding methods. Among them, the neutral point non-grounding system means that the neutral point of the power system (i.e., the common connection point of the three-phase power supply) is not directly connected to the ground. This grounding method is applicable to power transmission with a relatively low voltage level, short line length, and small capacitive current. When a single-phase grounding fault occurs in the neutral point non-grounding system, the grounding current is small, which will not cause a short-circuit current and will not immediately lead to power interruption, but the system can still continue to operate for a period of time. The arc suppression coil grounding system is based on the neutral point non-grounding system and compensates for the grounding capacitive current by connecting an arc suppression coil. The arc suppression coil is a magnetic component that compensates for the grounding capacitive current through inductance action, reducing the grounding current and thus reducing the impact of the grounding fault on the system. The arc suppression coil grounding system can improve the power supply reliability of the system and reduce the damage to equipment caused by grounding faults, but it also increases the complexity and cost of the system.

[0003] The two small current grounding system methods of the neutral point not grounded or grounded through an arc suppression coil have the following advantages: improving the reliability of the system: when a single-phase grounding fault occurs, the system can still continue to operate without immediate power outage, improving the continuity of power supply. Reducing the fault current: The grounding fault current in the small current grounding system is small, with lower requirements for the thermal stability of equipment, reducing the risk of equipment damage. Easy to maintain and repair: Due to the small grounding current, fault detection and location are relatively easy, facilitating maintenance and repair work.

[0004] However, they also have some limitations. When a single-phase grounding fault occurs in the system, the grounding fault current is often very small, and it may be relatively difficult to select and locate the grounding fault line. Content of the Utility Model

[0005] The purpose of the utility model is to provide a small power source grounding fault line selection device to solve the above technical problems.

[0006] To achieve the above purpose, the utility model provides the following technical solutions:

[0007] A small power source grounding fault line selection device, the device includes:

[0008] A plurality of monitoring units, the plurality of monitoring units are respectively used to be installed on each node of each phase of the three-phase circuit for collecting the zero-sequence current of each node;

[0009] A processing unit, which is respectively connected to a plurality of monitoring units, is configured to receive the zero-sequence currents of each node collected by the plurality of monitoring units, and select the branch where the ground fault occurs based on the zero-sequence currents of each node, so as to realize single-phase ground fault line selection;

[0010] A cut-off unit, which is connected in series to each node of each phase of the three-phase circuit, and the processing unit is connected to the cut-off unit, and is configured to control the cut-off unit to act.

[0011] Further, each of the plurality of monitoring units includes:

[0012] A zero-sequence current transformer, which is configured to collect the zero-sequence currents of each node of each phase of the three-phase circuit;

[0013] A differential protection control module, which is configured to collect the zero-sequence current collected by the zero-sequence current transformer at its corresponding node, and convert the zero-sequence current into a digital current signal.

[0014] Further, the processing unit is a main controller;

[0015] The main controller is connected to each differential protection control module, and is configured to receive and analyze the digital current signals of each node to determine the branch where the single-phase ground fault occurs, and control the cut-off unit corresponding to the zero-sequence current transformer to act.

[0016] Further, the main controller is a microcomputer.

[0017] Further, the device further includes a communication module;

[0018] The main controller is connected to the communication module, and is configured to upload the detected single-phase ground fault line selection information to the remote monitoring center in real time through the communication module.

[0019] Further, the device further includes a fault indication unit;

[0020] The processing unit is connected to the fault indication unit, and is configured to control the fault indication unit to alarm when a single-phase ground fault is detected.

[0021] Further, the zero-sequence current transformer has a primary winding and a secondary winding;

[0022] The primary winding of the zero-sequence current transformer is sleeved on each node of each phase of the three-phase circuit;

[0023] Both ends of the secondary winding of the zero-sequence current transformer are provided with terminal blocks, and the secondary winding of the zero-sequence current transformer is connected to the differential protection control module at its corresponding node through the terminal blocks provided at both ends of the winding.

[0024] Further, the cut-off unit is a circuit breaker.

[0025] Advantages of the present utility model: By installing monitoring units at each node of the three-phase circuit, the zero-sequence current at each node can be collected and transmitted to the processing unit. The processing unit selects the branch where the grounding fault occurs based on the zero-sequence current of each node collected by each zero-sequence current transformer, realizes the line selection for three-phase grounding faults, can quickly and accurately locate the single-phase grounding fault in the transmission line, and controls the cut-off of the faulty line through the cut-off unit, providing a strong guarantee for the safe and stable operation of the power system;

[0026] It is equipped with a communication module, which can remotely upload and monitor fault information, improving the operation and maintenance efficiency.

[0027] These and other objects, features, and advantages of the present utility model are fully embodied through the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It shows a schematic block diagram of the principle of the small power source grounding fault line selection device of the present utility model.

[0029] Figure 2 It shows a schematic diagram of the use state of the small power source grounding fault line selection device of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following description is used to disclose the present utility model so that those skilled in the art can implement the present utility model. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description can be applied to other implementation schemes, variant schemes, improvement schemes, equivalent schemes, and other technical schemes that do not deviate from the spirit and scope of the present utility model.

[0031] Those skilled in the art should understand that in the disclosure of the specification, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or modules does not necessarily have to be limited to those steps or modules clearly listed, but may include other steps or modules that are not clearly listed or are inherent to these processes, methods, products, or devices. Therefore, the above terms should not be construed as limitations to the present utility model.

[0032] It can be understood that the term "one" should be understood as "at least one" or "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of the element can be multiple. The term "one" should not be construed as a limitation on the number.

[0033] A small power source grounding fault line selection device according to a preferred embodiment of the present utility model will be elaborated in detail below, in which, in combination withFigure 1 and Figure 2 , the device includes: a plurality of monitoring units, a processing unit, and a cut-off unit.

[0034] The plurality of monitoring units are respectively used to be installed on each node of each phase of the three-phase circuit for collecting the zero-sequence current of each node.

[0035] The processing unit is respectively connected to the plurality of monitoring units, and is used to receive the zero-sequence current of each node collected by the plurality of monitoring units, and select the branch where the ground fault occurs based on the zero-sequence current of each node, so as to realize single-phase ground fault line selection.

[0036] The cut-off unit is connected in series on each node of each phase of the three-phase circuit, and the processing unit is connected to the cut-off unit for controlling the cut-off unit to act.

[0037] By installing monitoring units on each node of the three-phase circuit, the utility model can collect the zero-sequence current on each node, and transmit the collected zero-sequence current to the processing unit. The processing unit selects the branch where the ground fault occurs based on the zero-sequence current of each node of each phase collected by each zero-sequence current transformer, realizes the line selection of three-phase ground faults, can quickly and accurately locate the single-phase ground fault in the transmission line, and controls the cut-off of the fault line through the cut-off unit, providing a strong guarantee for the safe and stable operation of the power system.

[0038] In this embodiment, each of the plurality of monitoring units includes a zero-sequence current transformer and a differential protection control module. The zero-sequence current transformer is used to collect the zero-sequence current on the nodes of the three-phase circuit. The differential protection control module is used to collect the zero-sequence current collected by the zero-sequence current transformer on its corresponding node, and convert the zero-sequence current into a digital current signal.

[0039] The zero-sequence current transformer is provided with a primary winding and a secondary winding. The primary winding of the zero-sequence current transformer is sleeved on the nodes of each phase of the three-phase circuit. Wiring terminals are arranged at both ends of the secondary winding of the zero-sequence current transformer. The secondary winding of the zero-sequence current transformer is connected to the differential protection control module on its corresponding node through the wiring terminals arranged at both ends of the winding.

[0040] In the three-phase circuit, when there is a single-phase ground fault, a zero-sequence current will be generated. The primary winding of the zero-sequence current transformer is sleeved on the nodes of the three-phase circuit. When there is a zero-sequence current in the three-phase circuit, the primary winding of the zero-sequence current transformer generates an induced electromotive force that is proportional to the magnitude of the zero-sequence current and has the opposite direction. The zero-sequence current transformer can detect this tiny current change, generate an induced electromotive force, and transmit the induced electromotive force to the differential protection control module through the secondary winding of the zero-sequence current transformer.

[0041] The differential protection control module monitors the change of the current collected by the zero-sequence current transformer, converts the collected current from an analog signal to a digital signal and transmits it to the processing unit. The processing unit collects the zero-sequence current from different nodes and determines whether there is a fault based on the collected zero-sequence current. If the processing unit determines that a ground fault has occurred, an alarm is issued.

[0042] Exemplarily, circuit breakers are installed at each node where the zero-sequence current transformer is installed. When the processing unit determines that a ground fault has occurred, it controls the circuit breakers corresponding to the zero-sequence current transformers at both ends of the faulty line to trip, so as to cut off the faulty circuit.

[0043] Exemplarily, the processing unit is a main controller, which is connected to each differential protection control module and is used to receive and analyze the digital current signals of each node to determine the branch where a single-phase ground fault occurs, and control the circuit breaker corresponding to the zero-sequence current transformer to disconnect, so as to realize the selection of the single-phase ground fault line. The main controller is a microcomputer.

[0044] Exemplarily, the device further includes a communication module. The main controller is connected to the communication module and is used to upload the detected single-phase ground fault line selection information to the remote monitoring center in real time through the communication module, so as to improve the operation and maintenance efficiency.

[0045] Exemplarily, the device further includes a fault indication unit. The processing unit is connected to the fault indication unit and is used to control the fault indication unit to alarm when a single-phase ground fault is detected.

[0046] Working principle:

[0047] This device includes a zero-sequence current transformer that can be installed on a branch. The zero-sequence current transformer is used to monitor the zero-sequence current in the branch. When a single-phase ground fault occurs, the zero-sequence current of the faulty line increases significantly, and the zero-sequence current of the faulty line will be much larger than that of the non-faulty line. The zero-sequence current transformer transmits the detected analog current signal to the differential protection control module, and the differential protection control module converts the analog signal into a digital signal and transmits it to the processing unit.

[0048] The processing unit receives the zero-sequence current signals from each node and performs a threshold judgment on the magnitudes of the received zero-sequence current signals of each node to determine whether there is a single-phase ground fault in the line between two adjacent nodes. In this embodiment, the processing unit is a main controller, and the main controller is a microcomputer.

[0049] When the main controller determines that a single-phase ground fault has occurred in a certain branch, it will immediately trigger the fault indication unit. The fault indication unit alarms through a buzzer to remind the operation and maintenance personnel to pay attention.

[0050] At the same time, the main controller uploads the fault information to the remote monitoring center through the communication module to realize the remote monitoring of the fault.

[0051] Those skilled in the art should understand that the embodiments of the present utility model described above and shown in the accompanying drawings are only examples and do not limit the present utility model. The advantages of the present utility model have been fully and effectively realized. The functions and structural principles of the present utility model have been shown and described in the embodiments, and the embodiments of the present utility model may have any variations or modifications without departing from the said principles.

Claims

1. A small power supply grounding fault line selection device, characterized in that The device includes: A plurality of monitoring units, which are respectively used to be installed on each node of each phase of the three-phase circuit for collecting the zero-sequence current of each node; A processing unit, which is connected to the plurality of monitoring units respectively, and is used to receive the zero-sequence current of each node collected by the plurality of monitoring units, and select the branch where the ground fault occurs based on the zero-sequence current of each node to realize single-phase ground fault line selection; A cutting-off unit, which is connected in series on each node of each phase of the three-phase circuit, and the processing unit is connected to the cutting-off unit for controlling the cutting-off unit to act.

2. The small power source grounding fault line selection device according to claim 1, wherein Each of the plurality of monitoring units includes: A zero-sequence current transformer, which is used to collect the zero-sequence current on the nodes of each phase of the three-phase circuit; A differential protection control module, which is used to collect the zero-sequence current collected by the zero-sequence current transformer at its corresponding node and convert the zero-sequence current into a digital current signal.

3. The small power source grounding fault line selection device according to claim 2, wherein The processing unit is a main controller; The main controller is connected to each differential protection control module, and is used to receive and analyze the digital current signals of each node to determine the branch where the single-phase ground fault occurs, and control the cutting-off unit corresponding to the zero-sequence current transformer to act.

4. The small power source grounding fault line selection device according to claim 3, characterized in that, The main controller is a microcomputer.

5. The small power source grounding fault line selection device according to claim 4, characterized in that, The device further includes a communication module; The main controller is connected to the communication module, and is used to upload the detected single-phase ground fault line selection information to the remote monitoring center in real time through the communication module.

6. The small power source grounding fault line selection device according to claim 1, characterized in that The device further includes a fault indication unit; The processing unit is connected to the fault indication unit, and is used to control the fault indication unit to alarm when a single-phase ground fault is detected.

7. The small power source grounding fault line selection device according to claim 2, characterized in that, The zero-sequence current transformer is provided with a primary winding and a secondary winding; The primary winding of the zero-sequence current transformer is sleeved on the nodes of each phase of the three-phase circuit; Both ends of the secondary winding of the zero-sequence current transformer are provided with connection terminals, and the secondary winding of the zero-sequence current transformer is connected to the differential protection control module at its corresponding node through the connection terminals arranged at both ends of the winding.

8. The small power source grounding fault line selection device according to claim 1, characterized in that The cutting-off unit is a circuit breaker.

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