Small-current earth fault line selection method based on fault signal transient state correlation analysis

Abstract

The invention relates to a small-current earth fault line selection method based on fault signal transient state correlation analysis, and belongs to the technical field of power distribution network automation. The technical problems in power distribution network single-phase earth fault line selection are solved. The small-current earth fault line selection method is characterized in that a feeder three-phase current is led in, the two-phase current difference of each feeder is obtained, correlation analysis is carried out on a feeder zero-sequence current and respective two-phase current differences, and a comprehensive correlation coefficient matrix E is formed; rhomax and rhomin in the E are selected, and if rhomax-rhomin>=rhoset, it is judged that the system has a single-phase earth fault, and fault lines are the feeders corresponding to rhomax; if rhomax-rhomin< rhoset, it is judged that the single-phase earth fault happens at the position of a busbar. The small-current earth fault line selection method is suitable for 35kV and 10kV voltage-class neutral-point non-effectiveness earthed line-cable mixed power distribution networks. The small-current earth fault line selection method has the advantages of being good in instantaneity, high in adaptability and high in accuracy rate, and the project practical value is achieved.

Description

Technical field [0001] The invention belongs to the technical field of electrical engineering, and relates to a small current grounding fault line selection method based on transient correlation analysis of a fault signal. Background technique [0002] Most of the domestic medium-voltage distribution networks use low-current grounding, that is, the neutral point is not grounded, grounded through high resistance, or grounded through arc suppression coils. When a single-phase grounding fault occurs, the fault current is small and the arc is unstable. Various fault line selection techniques based on steady-state quantities are not ideal in actual use. When a single-phase ground fault occurs, there is a relatively obvious transient process. In a short period of time, the transient grounding capacitance current is often several to several tens of times larger than its steady state. This process contains rich fault characteristics, which is the fault line selection Provides favorable ...

AI Technical Summary

Problems solved by technology

When a single-phase ground fault occurs on a feeder line composed of cables and overhead lines, the mixed line is prone to oscillation, and direct correlation analysis between it and the zero-sequence current of the line without oscillation will easily lead to inaccurate line selection; In the distribution network where the neutral point is grounded through the arc suppression coil, the compensation of the inductive current will affect the amplitude and phase of the zero-sequence current of the fault line, so that the traditional correlation analysis may cause line selection errors

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