Method for acquiring zero-sequence current transient starting point during single-phase earth fault of power distribution network

Abstract

The invention relates to a method for acquiring a zero-sequence current transient starting point during a single-phase earth fault of a power distribution network. The method comprises the following steps of: alternating-current sampling is made on an outgoing line end and each branch line of a transformer substation at the same sampling frequency by adopting a PMU and a transient recording type fault indicator; when a single-phase earth fault occurs, the PMU and the transient wave recording type fault indicator upload a fault wave recording waveform to a main station; the main station analyzes the bus zero-sequence voltage waveform uploaded by the PMU and finds the position of a zero-sequence voltage sudden change point through a periodic amplitude comparison method; and the transient starting point position of the zero-sequence current of the transient recording type fault indicator is acquired through time conversion. The acquisition of the transient starting point of the zero-sequence current signal of the high-frequency unstable transient recording type fault indicator is converted into the acquisition of the abrupt change point of the zero-sequence voltage signal of the low-frequency stable PMU, so that the error probability is reduced, and the acquisition accuracy is improved.

Description

technical field [0001] The invention belongs to the technical field of state monitoring of overhead lines in a distribution network, and in particular relates to a method for acquiring a zero-sequence current transient starting point when a single-phase grounding fault occurs in a distribution network. Background technique [0002] The distribution network is the carrier of urban and rural power supply. The stability and safety of the distribution network are directly related to the safety of power supply for thousands of households, and have important economic value and social significance. Single-phase ground fault is the most common form of fault in the distribution network. In the past, after the fault occurred, manual investigation was required, and the troubleshooting took a long time and was inefficient. [0003] Transient state recording type fault indicator is an effective single-phase ground fault automatic positioning tool and means. The product integrates new tec...

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Problems solved by technology

The zero-sequence current of the transient recording type fault indicator is synthesized by the current waveform of the three-phase acquisition unit. The sampling errors of the three acquisition units are superimposed. At the same time, the structure of the line itself and the load condition are relatively complex, and the load fluctuation is unstable. ; figure 2 It is the real zero-sequence current waveform interception of the transient wave-recording type fault indicator. From the waveform, there are a lot of glitches in the zero-sequence current waveform. The master station searches for the starting point of the transient signal through the zero-sequence current waveform itself, and obtains the first half-wave data after the fault. very difficult

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