A device for detecting single-phase grounding fault of distribution network of primary and secondary fuse switch set

Abstract

The application relates to a network distribution single-phase grounding fault detection device for a secondary fusion switch set, which comprises a main control board, a collection board and an external terminal unit, the collection board is provided with voltage sensors and current sensors, the external terminal unit is integrated with voltage, current, control input and output interfaces, a power supply and a communication interface, the external terminal unit is connected with the main control board through the collection board; a primary switch unit leads out remote signaling, remote control lines as well as current lines and voltage lines, the three lines are respectively connected with the control, current and voltage input interfaces, the detection device corresponds to lead out three outgoing line connection controllers, the power supply and the communication interface are connected with the controller; the detection device collects the voltage and current signals of the primary switch unit, uploads the processed single-phase grounding fault signal and broken line fault signal to the controller, and sends the detection result to the main station through the controller. The device is not only beneficial to improving the accuracy of network distribution fault detection, but also simple in structure and easy to implement.

Description

Technical Field

[0001] This invention belongs to the field of power distribution network technology, and specifically relates to a single-phase grounding fault detection device for a power distribution network using a primary and secondary integrated switchgear. Background Technology

[0002] Key nodes such as the main protection section points of overhead lines, T-junctions of major branches, important boundary points, and main ring network substations of cable lines should be equipped with integrated primary and secondary protection systems. These systems should be capable of determining single-phase grounding faults based on zero-sequence voltage and current signals. However, traditional integrated primary and secondary protection systems are prone to false alarms and missed alarms, and have weak anti-interference capabilities, directly affecting the accuracy of fault diagnosis. Statistics show that 70% to 80% of distribution network faults are single-phase grounding faults. With the deepening construction of digital distribution networks, fault handling capabilities need further strengthening; therefore, improving the reliability of distribution network power supply remains a key focus of power grid construction.

[0003] In my country's power distribution network, the main neutral grounding methods are neutral point grounding via arc suppression coil and neutral point ungrounded grounding. The advantage of these methods is that the power grid can continue to operate for a period of time after a single-phase ground fault. The disadvantage is that the electrical characteristics after the fault are not obvious, making it difficult to quickly locate the fault point. When a single-phase ground fault occurs on a line, a fault point is formed. The line where the fault point is located is called the faulty line, and the lines outside the faulty line are called non-faulty lines. Before the fault, the line only has normal voltage and current. After the fault, the line exhibits zero-sequence voltage and zero-sequence current. Therefore, integrated primary and secondary equipment often uses zero-sequence voltage with large amplitude variations as the starting condition for fault analysis, and uses transient zero-sequence current signals with rich fault characteristics as the judgment condition for fault interval location or line selection. This method is generally called the transient zero-sequence power method.

[0004] The zero-sequence power direction judgment criterion of the integrated primary and secondary switching equipment has significant flaws. Relying solely on zero-sequence voltage for startup, it is prone to missed alarms when the zero-sequence voltage is set too high; conversely, when the zero-sequence voltage is set too low, due to technical loopholes in the traditional algorithm that fail to consider filtering for phase loss faults and interference signals during normal operation, false alarms are severe after commissioning. Therefore, upgrading the existing equipment is necessary. However, upgrading switchgear often involves power outages and requires the disassembly and modification of the existing equipment, resulting in high costs. Summary of the Invention

[0005] The purpose of this invention is to provide a single-phase grounding fault detection device for distribution networks using integrated primary and secondary switches. This device not only improves the accuracy of distribution network fault detection, but also has a simple structure and is easy to implement.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a single-phase grounding fault detection device for a distribution network using a primary and secondary integrated switchgear, comprising a main control board, a data acquisition board, and an external terminal unit. The data acquisition board is equipped with voltage sensors and current sensors for acquiring voltage and current signals. The external terminal unit integrates input and output interfaces for voltage, current, and control, as well as power and communication interfaces. The external terminal unit is connected to the main control board via the data acquisition board to transmit the acquired signals to the main control board for processing. Two lines are led out from the primary switchgear unit of the primary and secondary integrated switchgear, one of which... The control line and current line branch into remote signaling line, remote control line, and current line, with another line being a voltage line. These three lines are respectively connected to the control, current, and voltage input interfaces of the detection device. The control, current, and voltage output interfaces of the detection device have three corresponding outgoing lines connected to the controller of the primary and secondary integrated equipment. The power supply and communication interfaces of the detection device are connected to the controller. The detection device is connected in series between the primary switching unit and the controller, collecting the voltage and current signals of the primary switching unit, uploading the processed single-phase ground fault signal and open-circuit fault signal to the controller, and sending the detection results to the main station through the controller.

[0007] Furthermore, the current loop adopts a series structure, that is, the current sensor on the acquisition board is connected in series between the current input interface and the current output interface to acquire the current signal of the primary switching unit.

[0008] Furthermore, the voltage circuit adopts a parallel structure, that is, the voltage sensor on the acquisition board is connected in parallel on the connection line between the voltage input interface and the voltage output interface, so that the controller and the detection device can acquire the voltage signal of the secondary voltage terminal of the primary switching unit in parallel.

[0009] Furthermore, the remote signaling and remote control circuits adopt a parallel structure, that is, the remote signaling and remote control access terminals on the acquisition board are connected in parallel to the connection line between the control input interface and the control output interface, so that the controller and the detection device can simultaneously acquire the remote signaling and remote control signals of the primary switching unit.

[0010] Furthermore, the power supply and communication circuit adopt a direct connection structure, that is, the detection device is directly connected to the controller for communication through the power supply and communication interface, without connecting to the primary switching unit, and the controller supplies power to the detection device through the power supply and communication interface.

[0011] Furthermore, the detection device has an all-aluminum waterproof housing, and the main control board, acquisition board and external terminal unit are located inside the all-aluminum waterproof housing. The all-aluminum waterproof housing has interface embedding holes for embedding each interface, and all interfaces use waterproof aviation plugs.

[0012] Furthermore, the operating method of the detection device is as follows:

[0013] 1) When a single-phase ground fault occurs on the line, the detection device calculates the detection result based on the collected signal, sends the detection result to the controller, the controller configures the detection result at the single-phase ground fault point in the original point table, and uploads the detection result to the main station;

[0014] 2) When a line break occurs, the detection device calculates the detection result based on the collected signal, sends the detection result to the controller, the controller configures the detection result at the new point in the original point table, and uploads the detection result to the main station;

[0015] 3) When a single-phase ground fault and a line break fault occur simultaneously on the line, the detection device shall simultaneously detect and handle the single-phase ground fault and the line break fault in accordance with the methods in 1) and 2).

[0016] Compared with existing technologies, this invention has the following advantages: It provides a single-phase grounding fault detection device for distribution networks using integrated primary and secondary switchgear, suitable for 10kV distribution network systems. This device overcomes the problems of false alarms, missed alarms, and low accuracy in existing technologies, improving the accuracy and convenience of detecting single-phase grounding faults and network outages in distribution networks. Furthermore, the device has a simple and compact structure, is easy to implement, and requires no line shutdown, no changes to the equipment structure, and no disassembly of existing equipment. By using an external single-phase grounding fault detection device in conjunction with integrated primary and secondary switchgear, it overcomes the problems of lack of open-circuit fault detection and low accuracy in single-phase grounding fault detection. This provides an effective solution for uninterrupted upgrades of existing integrated primary and secondary switchgear, effectively ensuring the safe and stable operation of the distribution system. Therefore, this invention has strong practicality and broad application prospects. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the device connection circuit according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the current loop connection in an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the voltage loop connection in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the remote signaling and remote control circuit connection in an embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the power supply and communication circuit connection in an embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] like Figure 1-5 As shown, this embodiment provides a single-phase grounding fault detection device for a distribution network using a primary and secondary integrated switchgear. The detection device includes a main control board, a data acquisition board, and an external terminal unit. The data acquisition board is equipped with voltage and current sensors for acquiring voltage and current signals. The external terminal unit integrates input and output interfaces for voltage, current, and control signals, as well as power and communication interfaces. The external terminal unit is connected to the main control board via the data acquisition board to transmit the acquired signals to the main control board for processing. Two lines are led out from the primary switchgear unit of the primary and secondary integrated switchgear, one for control... The control line and current line branch into remote signaling line, remote control line, and current line, with another line being a voltage line. These three lines are respectively connected to the control, current, and voltage input interfaces of the detection device. The control, current, and voltage output interfaces of the detection device have three corresponding outgoing lines connected to the controller of the primary and secondary integrated equipment. The power supply and communication interfaces of the detection device are connected to the controller. The detection device is connected in series between the primary switching unit and the controller, collecting the voltage and current signals of the primary switching unit, uploading the processed single-phase ground fault signal and open-circuit fault signal to the controller, and sending the detection results to the main station through the controller.

[0026] like Figure 2 As shown, the current loop adopts a series structure, that is, the current sensor on the acquisition board is connected in series between the current input interface and the current output interface, and the primary switching unit, detection device, and controller are connected in series to acquire the current signal of the primary switching unit. The current input interface of the detection device adopts an open-circuit protection design, and the output interface uses a fixed cable configuration to prevent misoperation. Hot-plugging is achieved during installation and removal, solving the problem of ineffective power outage during the upgrade and transformation of integrated primary and secondary equipment, and reducing the difficulty of the transformation.

[0027] like Figure 3As shown, the voltage loop adopts a parallel structure, meaning the voltage sensor on the acquisition board is connected in parallel to the connection line between the voltage input interface and the voltage output interface, allowing the controller and detection device to acquire the voltage signal from the secondary voltage terminal of the primary switching unit in parallel. The voltage loop employs voltage threshold protection measures; when the acquired voltage value is too high, automatic limit protection is applied to prevent equipment damage.

[0028] like Figure 4 As shown, the remote signaling and remote control circuits adopt a parallel structure, that is, the remote signaling and remote control access terminals on the acquisition board are connected in parallel to the connection line between the control input interface and the control output interface, so that the controller and the detection device can simultaneously acquire the remote signaling and remote control signals of the primary switching unit. The remote control circuit adopts a virtual parallel structure, where the controller can directly control the switching state, but the detection device cannot control the switching state.

[0029] like Figure 5 As shown, the power supply and communication circuit adopt a direct connection structure, that is, the detection device is directly connected to the controller for communication through the power supply and communication interface, without connecting to the primary switching unit, and the controller supplies power to the detection device through the power supply and communication interface.

[0030] The detection device, as a supporting component of the primary and secondary integrated equipment, integrates a data acquisition board, a main control board, and external terminals. The data acquisition board mainly consists of voltage and current transformers, responsible for acquiring voltage and current signals at a sampling rate of 256 points / cycle, twice that of traditional equipment. The acquisition board transmits the acquired voltage and current signals to the main control board. The main control board mainly consists of a high-performance STM32H743 CPU and some peripheral communication circuits, responsible for signal acquisition, analysis, and processing. The STM32H743 chip features a Cortex-M7 core (with double-precision floating-point units), operating at 480MHz, with a CPU clock speed of 400MHz. The Flash execution program utilizes its L1 cache to achieve zero-wait execution.

[0031] In this embodiment, the detection device has an all-aluminum waterproof housing. The main control board, data acquisition board, and external terminal unit are located inside the all-aluminum waterproof housing. The all-aluminum waterproof housing has interface embedding holes for embedding each interface. All interfaces adopt a waterproof aviation plug design, and the structure is the same as the original equipment's aviation plug structure. There is no need to change the original equipment's hardware structure. The overall equipment protection level reaches IP65, and it can operate stably for a long time in a humid and hot environment.

[0032] This invention possesses both single-phase grounding fault detection and open-circuit fault detection functions. The single-phase grounding fault detection function replaces this function in the original integrated primary and secondary equipment, improving the accuracy of single-phase grounding fault detection. The open-circuit fault detection function is a new addition, absent in the original equipment. The operating method of the detection device is as follows:

[0033] 1) When a single-phase ground fault occurs on the line, the detection device calculates the detection result based on the collected signal, sends the detection result to the controller, the controller configures the detection result at the single-phase ground fault point in the original point table, and uploads the detection result to the main station;

[0034] 2) When a line break occurs, the detection device calculates the detection result based on the collected signal, sends the detection result to the controller, the controller configures the detection result at the new point in the original point table, and uploads the detection result to the main station;

[0035] 3) When a single-phase ground fault and a line break fault occur simultaneously on the line, the detection device shall simultaneously detect and handle the single-phase ground fault and the line break fault in accordance with the methods in 1) and 2).

[0036] In real-world field tests, this device achieved a fault identification efficiency of over 90%, significantly improving identification accuracy and greatly reducing false alarms and missed alarms.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A single-phase grounding fault detection device for a distribution network using a primary and secondary integrated switchgear, characterized in that, The system includes a main control board, a data acquisition board, and an external terminal unit. The data acquisition board is equipped with a voltage sensor for acquiring voltage signals and a current sensor for acquiring current signals. The external terminal unit integrates input and output interfaces for voltage, current, and control, as well as power and communication interfaces. The external terminal unit is connected to the main control board via the data acquisition board to transmit the acquired signals to the main control board for processing. The primary switching unit of the integrated primary and secondary equipment has two leads: one for control and current, branching into remote signaling, remote control, and current lines; and the other for voltage. These three lines are respectively connected to the control, current, and voltage input interfaces of the detection device. The control, current, and voltage output interfaces of the detection device have three corresponding leads connected to the controller of the integrated primary and secondary equipment. The power and communication interfaces of the detection device are connected to the controller. The detection device is connected in series between the primary switching unit and the controller, acquiring the voltage and current signals of the primary switching unit, uploading the processed single-phase grounding fault signal and open-circuit fault signal to the controller, and then sending the detection results to the main station through the controller. The current loop adopts a series structure, connecting the current sensor on the acquisition board in series between the current input interface and the current output interface to acquire the current signal of the primary switching unit; The voltage circuit adopts a parallel structure, with the voltage sensor on the acquisition board connected in parallel on the connection line between the voltage input interface and the voltage output interface, so that the controller and the detection device can acquire the voltage signal of the secondary voltage terminal of the primary switching unit in parallel. The remote signaling and remote control circuits adopt a parallel structure, connecting the remote signaling and remote control access terminals on the acquisition board in parallel on the connection line between the control input interface and the control output interface, so that the controller and the detection device can simultaneously acquire the remote signaling and remote control signals of the primary switching unit. The power supply and communication circuit adopts a direct connection structure. The detection device is directly connected to the controller for communication interaction through the power supply and communication interface, without being connected to the primary switching unit. The controller supplies power to the detection device through the power supply and communication interface. The detection device has an all-aluminum waterproof housing. The main control board, data acquisition board and external terminal unit are located inside the all-aluminum waterproof housing. The all-aluminum waterproof housing has interface embedding holes for embedding each interface. All interfaces use waterproof aviation plugs. The operating method of the distribution network single-phase grounding fault detection device for integrated primary and secondary switches is as follows: 1) When a single-phase ground fault occurs on the line, the detection device calculates the detection result based on the collected signal, sends the detection result to the controller, the controller configures the detection result at the single-phase ground fault point in the original point table, and uploads the detection result to the main station; 2) When a line breakage fault occurs, the detection device calculates the detection result based on the collected signal, sends the detection result to the controller, the controller configures the detection result at the new point in the original point table, and uploads the detection result to the main station; 3) When a single-phase ground fault and a line break fault occur simultaneously on the line, the detection device shall simultaneously detect and process the single-phase ground fault and the line break fault in accordance with the methods of 1) and 2).

Images