Wind power farm grid-connected power transmission line instant single-phase grounding fault single-end distance measuring method

Abstract

The invention discloses a wind power farm grid-connected power transmission line instant single-phase grounding fault single-end distance measuring method. Three-phase voltages and three-phase currents at two specific moments are acquired on a wind farm side, and are used as inputs, and the three-phase voltages and the three-phase currents acquired on the wind farm side at two specific moments are used to calculate corresponding positive, negative, zero sequence voltage, current phasors. Based on a power transmission line distribution parameter model, the calculated wind farm side voltage, current sequence components are used to establish voltage, current relations on two ends of a power transmission line. Power supply potential, equivalent system impedance, fault distances and transition resistors of a system side are adopted as unknown quantities, and an established non-linear electric equation set is solved by using an improved Levenbery-Marquardt method, and an accurate fault distance measuring result is acquired. A problem of wind power farm grid-connected power transmission line fault distance measurement is effectively solved.

Description

technical field [0001] The invention belongs to the technical field of power system protection and control, and in particular relates to a single-end single-end ranging method for instantaneous single-phase grounding faults of wind farm grid-connected transmission lines based on fault isolation multi-time information. [0002] technical background [0003] Accurate fault location when a fault occurs on a grid-connected transmission line of a wind farm can help shorten the line inspection time after a fault, speed up the troubleshooting of line faults and restore power supply, and is of great significance for improving the stability of the power system and ensuring the safe operation of the system. [0004] Actual operating data show that 80-90% of transmission line faults are single-phase ground faults, and most of them are instantaneous faults. The declared patent CN104198889A can well solve the problem of distance measurement of instantaneous single-phase ground faults on t...

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Problems solved by technology

The declared patent CN104198889A can well solve the problem of distance measurement of instantaneous single-phase ground faults on traditional transmission lines represented by thermal power transmission. The output characteristic is obviously different from the traditional thermal power supply, which makes the premise of the distance measurement method in the patent CN104198889A established: the equivalent impedance of the opposite end system remains constant during the entire fault isolation period, which is no longer true; in addition, the direct fault distance adopted in the patent CN104198889A The search algorithm is also not suitable for the weak fault current of the wind farm grid-connected transmission line. The above two factors lead to the inability of the existing method to perform accurate fault location

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