Using Distributed Parameters to Realize the Distance Protection Method of Line Single-phase-to-Earth Fault

Abstract

The invention discloses a line single-phase earth fault distance protection method implemented by the aid of distributed parameters. The line single-phase earth fault distance protection method includes computing line impedance from a power transmission line protection setting range position to a single-phase earth fault point by the aid of a distributed parameter model and fault-phase voltages, fault-phase currents, fault-phase negative-sequence currents and a zero-sequence current at a power transmission line protection mounting position; judging whether a line impedance phase angle between the power transmission line protection setting range position and the single-phase earth fault point is within a range between 60 degrees and 120 degrees or not so as to enable a protection device to transmit an action trip signal. The line single-phase earth fault distance protection method has the advantages that a physical model used in the method is the distributed parameter model, and the distributed parameter model has natural ability of resisting influence of distributed capacitance currents and is suitable for ultrahigh / extra-high-voltage alternating-current power transmission line single-phase earth fault relay protection methods; influence of transition resistance to the protection action performance is eliminated by the method in principle, and the ability of resisting the influence of the transition resistance is excellent.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for realizing line single-phase grounding fault distance protection by using distributed parameters. Background technique [0002] Impedance distance protection reflects the fault distance according to the measured impedance to distinguish whether the fault point is inside the protection zone or outside the protection zone. Impedance distance protection is less affected by power system operation mode and structural changes, and the electrical quantity used to calculate and measure impedance is the total fault component, which is applicable to the entire fault process. Therefore, impedance distance protection can be used not only for the main protection of high-voltage transmission lines, but also for the backup protection of EHV / UHV AC transmission lines. However, the action performance of impedance distance protection is seriously affecte...

AI Technical Summary

Problems solved by technology

Considering the influence of the distributed capacitive current along the transmission line, the relationship between the fault impedance and the fault distance is a hyperbolic tangent function. The amplitude and phase characteristics of the hyperbolic tangent function determine that the impedance relay has poor resistance to transition resistance, and the additional impedance brought by the transition resistance will seriously affect Action performance of impedance relay

EHV / UHV transmission lines transmit large-capacity electric energy and are heavy-duty 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.

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