Fault positioning method for common-tower double-circuit line

Abstract

A fault positioning method for a common-tower double-circuit line comprises the following steps: firstly, carrying out six-sequence decomposition for electrical quantity at two ends of the double-circuit line; next, calculating the fault distance by a long line equation of a transmission line of a same positive-sequence fault component of the six-sequence components, and obtaining six-sequence current of a fault point according to the electrical quantity at two ends of the double-circuit line, the fault distance and the long line equation; then converting the six-sequence current into six-phase current; and finally, judging a fault phase according to the amplitude value characteristic of the phase current of the fault point. According to the method provided by the invention, when fault phase-selection of the double-circuit line is carried out, the fault distance detection can be performed at the same time, and the advantages of clear principle, high distance detection accuracy, simple and reliable phase-selection logic and the like are provided. The method provided by the invention is free of the influence of fault point transitional resistance, circuit distributed capacitor current and load current, can automatically adapt to and regulate a definite value of the phase-selection criterion with the change of a system operation manner, and can provide effective phase-selection logic for distance protection of the common-tower double-circuit line.

Description

technical field [0001] The invention relates to a distance measurement and phase selection method for transmission line faults, belonging to the technical field of power transmission and distribution. Background technique [0002] With the development of modern power technology and the continuous increase of grid capacity, transmission line corridors are becoming more and more tense, especially in large and medium-sized cities. Since the two circuits share one tower, the double-circuit line on the same pole has the characteristics of narrow outlet corridor, less fertile land, fast construction speed, and significant economic benefits. It has been widely used in actual operation and planning and construction. [0003] The operation mode of the double-circuit line is complicated, and there are mutual inductance between lines and cross-line faults, which bring certain difficulties to fault location and phase selection of the six-line transmission system. In order to ensure uni...

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Problems solved by technology

The impedance phase selection method mainly confirms the fault phase based on the measurement results of the impedance measuring element, and can correctly select the fault phase under most simple faults, but it is greatly affected by the system operation mode and the transition resistance of the fault point, and the phase selection result is often not accurate. ideal

The voltage phase selection method needs to solve the sensitivity problem of long-distance faults on long lines and remote ground faults with transition resistance, and it cannot distinguish between phase-to-phase faults in the area or cross-line faults when used in a double-circuit line system on the same pole

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