CN-224231943-U - Single-phase grounding fault line selection device for low-current grounding system

CN224231943UCN 224231943 UCN224231943 UCN 224231943UCN-224231943-U

Abstract

The utility model discloses a single-phase grounding fault line selection device for a small-current grounding system, which belongs to the technical field of single-phase grounding fault detection of power systems, and comprises a PT/CT analog input module, a signal conditioning module, a data acquisition module and a data processing and control module which are sequentially connected, wherein the data acquisition module is also connected with a data buffer module, and is also respectively connected with a data storage module, a display module, an alarm module and a communication module, the signal conditioning module comprises a signal voltage regulating circuit and a signal filtering circuit, the data acquisition module is connected with an FPGA chip by two A/D converters, and judges whether a single-phase grounding fault occurs or not by monitoring zero sequence voltage at a bus through the FPGA chip, and the data processing and control module adopts an STM32 singlechip to perform data processing and analysis to select a fault line. The device adopts an FPGA+STM32 dual-core structure to replace the prior single processing structure, so that faults can be rapidly detected, and fault lines can be accurately judged.

Inventors

ZHAO GUOFEI
AN XIAOYU
DOU ZHIFENG
MA XINYUAN
LIU YUDUO
WANG QIAN
LU FALONG

Assignees

郑州蒂德科技有限公司

Dates

Publication Date: 20260512
Application Date: 20250516

Claims (8)

1. The single-phase grounding fault line selection device for the low-current grounding system is characterized by comprising a PT/CT analog input module, a signal conditioning module, a data acquisition module and a data processing and control module which are sequentially connected, wherein the data acquisition module is also connected with a data buffer module, and the data processing and control module is also respectively connected with a data storage module, a display module, an alarm module and a communication module; The PT/CT analog input module comprises input quantities of two analog signals, namely zero sequence voltage and zero sequence current, which are connected to a bus; The signal conditioning module comprises a signal voltage regulating circuit and a signal filtering circuit, wherein the input end of the signal conditioning module is connected with the PT/CT analog input module to regulate and filter a received analog signal, the signal voltage regulating circuit comprises a voltage transformer and a current transformer, the signal filtering circuit adopts a Butterworth low-pass filter, and the filtering circuit comprises two resistors, two capacitors and an operational amplifier; The data acquisition module is formed by connecting two A/D converters with an FPGA chip, the input end of the data acquisition module is connected with the output end of the signal conditioning module, the received analog signals after voltage regulation and filtration are converted into digital signals, and whether single-phase grounding faults occur or not is judged by monitoring zero sequence voltages at the bus through the FPGA chip, and data before and after the faults occur are buffered in the data buffering module; The data processing and control module is connected with the output end of the data acquisition module to receive fault signals, the data processing and control module adopts an STM32 singlechip to process and analyze data, the STM32 singlechip performs data transmission between the FPGA chip through an FSMC communication protocol, the data processing and control module analyzes and processes the data to select fault lines by reading pre-fault data and post-fault data cached by the data buffering module, and the data storage module is connected with the data processing and control module to store fault data when faults occur each time.
2. The single-phase grounding fault line selection device for the low-current grounding system according to claim 1, wherein in the data acquisition module, a set threshold value of zero sequence voltage at a monitoring bus of the FPGA chip is 30V-50V, and when the zero sequence voltage of the bus exceeds the set threshold value, the single-phase grounding fault is judged to occur.
3. The single-phase grounding fault line selection device for a small-current grounding system according to claim 1, wherein in the signal voltage regulating circuit, a voltage transformer is of a model TR1102-1C, a current transformer is of a model TR1102-2C, and the transformation ratios of the voltage transformer and the current transformer are 220:5V and 5A:5V respectively.
4. The single-phase grounding fault line selection device for a small-current grounding system as claimed in claim 1, wherein the cut-off frequency of a Butterworth low-pass filter adopted in the signal filtering circuit is 4KHz, two resistors are 4K resistors, two capacitors are 0.01uf capacitors, and the model of an operational amplifier is LM324.
5. The single-phase grounding fault line selection device for a low-current grounding system as claimed in claim 1, wherein in the data acquisition module, the model numbers of the two A/D converters are AD7606, and the model number of the FPGA chip is EP4CE10F17C8N.
6. The single-phase grounding fault line selection device for the low-current grounding system according to claim 1, wherein the display module adopts a Kunlun on touch screen TPC7022EX, receives control signals of the data processing and control module, displays three-phase voltage and zero-sequence voltage values at a bus, states of various feeder lines and fault occurrence time and ending time in real time, and displays a fault line number when the display module receives fault information, and simultaneously displays a fault line indicator lamp with a page corresponding number to turn red.
7. The single-phase grounding fault line selection device for the low-current grounding system as set forth in claim 1, wherein the alarm module is a SIM900A GSM module, and when a single-phase grounding fault occurs, the data processing and control module sends fault information to the alarm module, and the alarm module receives alarm signals of the data processing and control module and sends the fault information to a worker in a short message mode through the communication module.
8. A single-phase earth fault line selection apparatus for a low current grounding system as claimed in claim 1, wherein the input voltage of the power supply module is 24V and the output voltages are 15V, 5V and 3.3V.

Description

Single-phase grounding fault line selection device for low-current grounding system Technical Field The utility model belongs to the technical field of single-phase earth fault detection of power systems, and particularly relates to a single-phase earth fault line selection device for a low-current grounding system. Background The medium-voltage distribution network of 6-35 kv in China generally adopts a neutral point non-effective grounding operation mode, and can be roughly divided into a neutral point non-grounding system, a neutral point through arc suppression coil grounding system and a neutral point through high-resistance grounding system. The design characteristic of the operation mode is that when single-phase grounding faults occur, the phase voltage of the fault phase becomes zero, the phase voltage of the non-fault phase rises to be line voltage, the line voltage of the three phases still keeps symmetrical, the system can operate for 1-2 hours with faults, but the system can operate in a grounding mode for a long time, two or three phases are easy to break, and equipment is easy to damage. At present, when a single-phase grounding fault occurs in a small-current grounding system, the grounding fault current is small, the zero sequence current of each line is influenced by the structure and parameters of a power distribution network, the grounding mode of a neutral point and the transition resistance in grounding, and accurate line selection of the single-phase grounding fault of the resonant grounding system is difficult to realize by means of a small-current grounding line selection device formed by a single discrimination principle. Therefore, it is needed to design a single-phase ground fault line selection device, which can realize accurate detection of the phase ground fault of the low-current ground system. Disclosure of utility model The utility model aims to solve the problem of low detection accuracy of a small-current grounding line selection device in the prior art, and provides a single-phase grounding fault line selection device for a small-current grounding system, which can rapidly detect faults and accurately judge fault lines. The utility model adopts the following technical scheme that the single-phase grounding fault line selection device for the low-current grounding system comprises a PT/CT analog input module, a signal conditioning module, a data acquisition module and a data processing and control module which are sequentially connected, wherein the data acquisition module is also connected with a data buffer module, and the data processing and control module is also respectively connected with a data storage module, a display module, an alarm module and a communication module; the signal conditioning module comprises a signal voltage regulating circuit and a signal filtering circuit, the input end of the signal conditioning module is connected with the PT/CT analog input module to regulate and filter the received analog signals, the signal voltage regulating circuit comprises a voltage transformer and a current transformer, the signal filtering circuit adopts a Butterworth low-pass filter, the filtering circuit comprises two resistors, two capacitors and an operational amplifier, the data acquisition module is composed of two A/D converters connected with an FPGA chip, the input end of the data acquisition module is connected with the output end of the signal conditioning module to convert the received analog signals after voltage regulation and filtering into digital signals, the zero sequence voltage at the bus is monitored by the FPGA chip to judge whether single-phase grounding faults occur or not, the data buffer module buffers data before and after the faults occur, the input end of the data processing and control module is connected with the output end of the data acquisition module to receive fault signals, the data processing and control module adopts a single chip microcomputer (STM 32) to process and analyze the data, the STM32 singlechip is used for carrying out data transmission between the FSMC communication protocol and the FPGA chip, the data processing and control module is used for analyzing and processing the data to select a fault line by reading the pre-fault data and the post-fault data cached by the data buffer module, and the data storage module is connected with the data processing and control module and is used for storing fault data when faults occur each time. Further, in the data acquisition module, the set threshold value of the zero sequence voltage at the bus monitored by the FPGA chip is 30V-50V, and when the zero sequence voltage of the bus exceeds the set threshold value, the single-phase earth fault is judged to occur. Further, in the signal voltage regulating circuit, the model of the voltage transformer is TR1102-1C, the model of the current transformer is TR1102-2C, and the transformation ratio of the voltage transformer to the curr