Diagnosis method for single-phase line breakage grounding complex fault type of power distribution network based on zero sequence voltage

Abstract

The invention discloses a diagnosis method for a single-phase line breakage grounding complex fault type of a power distribution network based on a zero sequence voltage, and the method comprises the steps: setting a start value of the zero sequence voltage through determining a small current grounding mode; extracting voltage sampling data of each phase of N cyclic waves before a line breakage moment and N cyclic waves after a fault moment, and calculating and obtaining the phase difference relation between the phase of the fault phase voltage before the fault and the phase of the steady-state zero sequence voltage after the fault and a reference function as the criterion through the FFT and a symmetrical component algorithm; judging whether the zero sequence voltage exceeds the start value or not: carrying out the extraction if the zero sequence voltage exceeds the start value and judging whether the phase difference between the phase of the zero sequence voltage and the phase of the fault phase voltage before the fault is corresponding to a load side grounding range of the criterion or not: determining that the fault is a single line breakage and load side grounding fault if the phase difference is corresponding to the load side grounding range of the criterion, or else determining that the fault is a single line breakage and power side grounding fault. The method is good in universality, and is suitable for power distribution networks at various voltage levels, wherein the neutral points of the power distribution networks are not grounded or the power distribution networks are grounded through arc suppression coils. Moreover, the deviation angle is not affected by the voltage level.

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...

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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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