A single-phase-to-ground fault line selection method based on post-fault waveform correlation analysis

Abstract

The invention relates to a single-phase earth fault line selection method based on post-fault wave correlation analysis, which relates to the electric system's power distribution field. The method comprises: accurately capturing the three-phase and zero-sequence current and the data of two sampling periods of the voltage signal after the fault through the measuring terminals installed on the lines; determining whether the two waveforms are similar or not through the solution of the correlation coefficient of the data of the same signal in two sampling periods; through the correlation coefficient calculation module, solving the correlation coefficients of the six pairs of waveforms respectively and comparing the correlation coefficients with the set value; if the number of the lines goes beyond the set number, then, determining that a single-phase earth fault takes place on the lines. According to the invention, the method is not influenced by the operation manners of the neural points. The method can be performed at a low cost and in a simple manner. Through the correlation coefficients of multiple signal waveforms to determine, the errors that arise from the use of a single waveform can be avoided so as to achieve the purpose of accurately determine a single-phase earth fault line.

Description

technical field [0001] The invention relates to the field of distribution of electric power systems, in particular to a method for line selection of single-phase grounding faults in a low-voltage distribution network. Background technique [0002] At present, my country's low-voltage distribution network generally adopts a small-current grounding method, mainly including a resonant grounding system grounded through an ungrounded system and an arc-suppression coil, and single-phase grounding faults are prone to occur during long-term operation. Single-phase-to-ground fault is the most frequent type of fault in distribution network. With the expansion of the power system, the number of outgoing lines is greatly increased, and the capacitive current of the system is greatly increased. After a fault occurs, the overvoltage of the power system will be caused, resulting in damage to the power equipment and endangering the safe operation of the system. Therefore, when a single-pha...

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Problems solved by technology

[0003] It is very difficult to find out the specific fault point with the traditional line inspection method

The line inspection method not only consumes a lot of manpower and material resources, but also prolongs the power outage time and affects the reliability of power supply

However, the electrical characteristic quantity after the single-phase ground fault in the distribution network is not obvious, and under different closing angles and distribution network operation modes, its characteristic quantity is complex and diverse

Due to the complexity of fault conditions and the influence of line structure parameters, nonlinear characteristics of transformers, electromagnetic interference and other factors, the spectrum characteristics, energy distribution and attenuation characteristics of fault transient zero-sequence currents are very different, so the distribution network has been lacking Reliable single-phase ground fault line selection method, traditional methods cannot comprehensively analyze and cause line selection difficulties

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