Two-point in-phase grounding fault analysis method and related device for small-resistance grounding system

Abstract

The invention discloses a two-point in-phase grounding fault analysis method and a related device for a small-resistance grounding system, and the method comprises the steps: drawing an equivalent zero-sequence network when a two-point grounding fault of the small-resistance grounding system occurs, and using a phasor analysis method to analyze the two-outlet in-phase grounding fault or a bus and outlet in-phase grounding fault of the system; extracting zero-sequence current phasors of all outgoing lines and neutral lines, and extracting the relative relation between the amplitude and the phase of all the zero-sequence currents. The fault feature focuses on describing the relative relation between zero-sequence currents of all measuring points after the fault instead of the absolute value, is not influenced by the fault distance and the fault point transition resistance, and still exists in the high-resistance grounding fault. And the maximum capacitance current extreme value 50A of a single line is analyzed, and the result has universality. And a theoretical basis is provided for solving two-point grounding protection and high-resistance grounding protection of a small-resistance grounding system.

Description

Technical field [0001] Technical Field The present application relates to electric power, in particular, it relates to a failure analysis method and related apparatus for low resistance grounding system with two-phase ground. Background technique [0002] Low resistance grounding system often use the field current flowing through the ground capacitive current protection feature of this zero sequence line formed when a ground fault occurs after the fault zero sequence current lines other than line failure, as a single-phase ground fault protection. The system when a lower resistance single-phase earth fault protection reliable operation, but in the high-resistance ground fault occurs, the fault detection difficult, are often protected tripping. When two o'clock same phase earth fault, since the zero sequence power increases, the ground becomes zero sequence current increases, increased zero-sequence voltage bus, as well as the respective fault line zero sequence current magnitude ...

AI Technical Summary

Problems solved by technology

[0004] This application provides a two-point in-phase ground fault analysis method and related devices for a small resistance grounding system, which are used to solve the technical problems caused by low protection sensitivity and poor universality in the prior art

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