Distance measuring method and type diagnostic method of single-phase grounding fault of electric transmission line

Abstract

The invention discloses a distance measuring method and a type diagnostic method of the single-phase grounding fault of an electric transmission line. In the distance measuring method, an amplitude value is calculated by utilizing the voltage, the current, the negative-sequence current and the zero-sequence current (phi is a fault phase: A phase, B phase, C phase) of the fault phase in a formed vector triangle according to the side-angle relationship of the vector triangle, because the fault distance x from a single-phase grounding fault point to a protected installation position is a positive real number, the fault distance x is obtained by utilizing division, the transition resistance value of the single-phase grounding fault is further calculated, and then the type of the single-phase grounding fault is diagnosed according to the condition of the transition resistance value of the single-phase grounding fault.

Description

technical field The invention relates to a diagnosis method for a single-phase ground fault of a power transmission line, in particular to a method for measuring the distance of a single-phase ground fault of a power transmission line and a method for diagnosing a fault type. Background technique Because distance protection is less affected by power system operation mode and structural changes, it can selectively remove various faults of transmission lines in an instant, and has been widely used in power system transmission line protection. The distance protection on the high-voltage transmission line is used as the main protection of the transmission line, and the distance protection on the EHV / UHV AC transmission line is used as the backup protection of the transmission line. At present, the distance protection widely used in power system transmission lines mainly includes power frequency variation distance protection and impedance distance protection. The power frequenc...

AI Technical Summary

Problems solved by technology

In the actual power system, the additional impedance generated by the transition resistance will seriously affect the action performance of the impedance distance protection

If the additional impedance generated by the transition resistance is resistive and inductive, it is easy to cause the impedance distance protection to refuse to operate when the ground fault occurs in the protected area;

High / super / extreme voltage AC transmission lines are often also heavy-load transmission lines. Heavy-load currents will reduce the action sensitivity of impedance distance protection, and the impact of heavy-load current on the action performance of impedance distance protection cannot be ignored.