Single-phase-to-earth fault relay protection method based on fault impedance phase characteristics

Abstract

The invention discloses a single-phase line earth fault relay protection method based on a fault impedance phase characteristic. The method comprises the steps that line fault impedance from a single-phase earth fault point to a protection setting range of the power transmission line is calculated by utilizing fault phase voltage, fault phase negative-sequence voltage, fault phase current and zero-sequence current at protection mounting of a power transmission line; whether a phase angle of the line fault impedance from the single-phase earth fault point to the protection setting range of the power transmission line is between 135 degrees and 225 degrees is judged; and if so, a protection device emits an action trip signal. The method overcomes influences of transition resistance and load current on the protection action performance, can correctly and reliably act during a single-phase high-resistance earth fault of the power transmission line, and is suitable for the single-phase earth fault relay protection of the power transmission line in the whole fault process.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a single-phase ground fault relay protection method based on fault impedance phase characteristics. Background technique [0002] The calculation formula of measuring line fault impedance z for traditional grounding distance protection is ,because ,therefore , that is, the line fault impedance z measured by the traditional grounding distance protection is composed of two parts, one part is the line fault impedance xz reflecting the real fault distance 1 , the other part is the additional fault impedance caused by the transition resistance . In the above formula, is the fault phase voltage; is the fault point voltage; is the fault phase current; is the zero-sequence current; φ is the fault phase: A phase, B phase, C phase; z 1 is the positive sequence impedance of the transmission line per unit length; z 0 is the zero-sequence imp...

AI Technical Summary

Problems solved by technology

[0003] The additional fault impedance caused by the transition resistance is likely to cause the traditional grounding distance protection to refuse or malfunction

The refusal of the traditional grounding distance protection will make the fault unable to be isolated from the power grid in time, which is not good for the safe and stable operation of the power grid; the wrong operation of the traditional grounding distance protection will lead to the expansion of the fault range, and even lead to a large shift of the power grid power flow, which will lead to large-scale power outages in the power grid

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