Diagnosis method of multiple fault types of single-phase disconnection and grounding in distribution network based on zero-sequence voltage

Abstract

The invention discloses a method for diagnosing multiple fault types of single-phase disconnection and grounding in a distribution network based on zero-sequence voltage. By determining the small current grounding mode, the starting value of zero-sequence voltage is set; The phase difference relationship between the fault phase voltage before the fault and the steady-state zero-sequence voltage phase after the fault and the reference function is obtained by calculating the phase voltage sampling data of N cycles after the fault moment by FFT and the symmetrical component algorithm as the judgment basis; judgment Whether the zero-sequence voltage exceeds the start-up value, if so, continue to extract, and judge whether the phase difference between the zero-sequence voltage phase and the fault phase voltage phase before the fault corresponds to the grounding range of the load side of the criterion, if yes, it is single-phase disconnection plus Ground fault on the load side, otherwise it is a single-phase disconnection plus a ground fault on the power side. The invention has good versatility, and is applicable to distribution networks with ungrounded neutral points or grounded through arc suppressing coils of various voltage levels, and the offset angle characteristics are not affected by voltage levels.

Description

technical field [0001] The invention relates to a zero-sequence voltage-based method for diagnosing multiple fault types of a single-phase disconnection and grounding of a power distribution network. Background technique [0002] The distribution network generally has the characteristics of wide distribution, short towers, thin wires, complex geographical environment, and is easily damaged by external forces. Failures happen from time to time. In the past, my country has always adopted the power construction development model of "emphasis on power generation, light supply, and no use". The construction of distribution network is seriously lagging behind, bottlenecks are common, and the adaptability is poor. The neutral point operation mode of my country's distribution network adopts the neutral point ungrounded mode or the arc suppressing coil grounded mode. After a single-phase ground fault occurs, no short-circuit loop is formed, and only a small zero-sequence current cau...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the above problems, the present invention proposes a zero-sequence voltage-based diagnosis method for single-phase disconnection and grounding complex faults in distribution networks. The fault electrical quantity used is the amplitude and phase of the steady-state zero-sequence voltage after the fault occurs. The invention fully considers the small current grounding method, the position of the grounding point after the line is broken, the influence of the transition resistance of the grounding point, and the sequence impedance characteristics of loads of different natures when there is a phase loss, and deeply analyzes the amplitude and phase of the zero-sequence voltage on the power supply side. The single-phase disconnection and grounding complex fault diagnosis method of the traditional distribution network single-phase disconnection and ground fault type based on sequence voltage amplitude and phase, solves the problem that the position of the grounding point cannot be judged after the disconnection

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