Ultra-high voltage AC transmission line three-phase short circuit fault distinguishing method based on single-end electric quantity

Abstract

The invention discloses an ultra-high voltage AC transmission line three-phase short circuit fault distinguishing method based on single-end electric quantity. Three-phase short circuit fault happens to an ultra-high voltage AC transmission line protection setting range, an angle of an inter-phase voltage at a protection mounting place when the ultra-high voltage AC transmission line operates normally ahead of an inter-phase voltage at the ultra-high voltage AC transmission line protection setting range after the three-phase short circuit fault happens to the ultra-high voltage AC transmission line falls in a range (90DEG 270 DEG), an angle of an another-phase voltage at the protection mounting place when the ultra-high voltage AC transmission line operates normally ahead of an another-phase voltage at the ultra-high voltage AC transmission line protection setting range after the three-phase short circuit fault happens to the ultra-high voltage AC transmission line falls in a range (90DEG 270 DEG), and when the above three conditions are true at the same time, the ultra-high voltage AC transmission line three-phase short circuit fault can be accurately distinguished, and influences of factors such as transition resistance, load current, a power system operation mode and the like on performance of a protection action can be eliminated.

Description

Technical field [0001] The invention relates to the technical field of power system relay protection, in particular to a method for judging three-phase short-circuit faults based on single-ended electrical quantities of UHV AC transmission lines. Background technique [0002] The power frequency variation distance protection constitutes distance protection by reflecting the sudden change of the working voltage amplitude. This method has the advantages of being less affected by the operation mode of the power system and strong resistance to transition resistance. However, because the sudden change of the working voltage amplitude used by this method only exists in the initial stage of the fault, it cannot be used as a backup protection for the ultra-high voltage AC transmission line. [0003] The impedance distance protection reflects the length of the fault distance according to the size of the fault impedance to distinguish whether the fault point is located in the protection zone...

AI Technical Summary

Problems solved by technology

Considering the influence of the ground capacitance along the line, the relationship between the fault impedance and the fault distance is a hyperbolic tangent function. The characteristics of the hyperbolic tangent function determine that the resistance of the impedance relay is poor, and the additional impedance brought by the transition resistance will seriously affect the impedance of the impedance relay. action performance

The ultra-voltage AC transmission line transmits large-capacity electric energy, and it is a heavy-duty transmission line. The heavy-load current will reduce the action sensitivity of the impedance distance protection, and the impact of the heavy-load current on the action performance of the impedance distance protection cannot be ignored.

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