Line inter-phase fault distance measuring method based on discrete sampling value

Abstract

The invention discloses a line inter-phase fault distance measuring method based on a discrete sampling value. According to the method, effects of inter-phase short circuit fault point voltage instantaneous values on inter-phase fault distance measuring accuracy are considered in an algorithm model, differential discrete processing is performed on differential equations, and fault inter-phase electric quantity sampling values of three adjacent sampling moments are used for calculating fault distances from inter-phase short circuit fault points to electric transmission line protection mounting positions. The method is used for measuring fault distances of inter-phase distance protection, the data amount required to be calculated is small, the calculation speed is fast, the measuring result is not affected by fault positions, transition resistors, system operation modes and load currents, and the measuring accuracy is better than fault distance measuring accuracy of traditional inter-phase distance protection.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for measuring fault distance between line phases based on discrete sampling values. Background technique [0002] The premise of traditional phase-to-phase distance protection assumes that the transition resistance is zero, and the phase-to-phase short-circuit fault is a metallic phase-to-phase short-circuit fault. For the differential equation Differential discrete processing is carried out, and the fault distance from the phase-to-phase short-circuit fault point to the transmission line protection installation is calculated by using the fault phase electrical quantity sampling values ​​at three adjacent sampling times. In the above formula, u is the fault phase-to-phase voltage; x is the fault distance; i is the fault phase-to-phase current; l 1 、r 1 are the positive-sequence inductance and positive-sequence resistance of the transmiss...

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Problems solved by technology

[0003] In actual faults, phase-to-phase short-circuit faults are mostly arc-type short-circuit faults. Although the transition resistance of arc-type short-circuit faults is not very large, the maximum arc-type phase-to-phase transition resistance can reach 65 ohms. The existence of transition resistance makes the fault distance measured by traditional phase-to-phase distance protection There is a deviation from the actual fault distance, and it is easy to cause misoperation or refusal of the phase-to-phase distance protection near the protection setting range, which has great hidden dangers to the safety and stability of the power grid

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