Power distribution network singlephase earth fault positioning method and system based on frequency sweep injection

Abstract

The invention provides a power distribution network singlephase earth fault positioning method and system based on frequency sweep injection; the system comprises a plurality of to-be-positioned lines; input ends of the plurality of to-be-positioned lines are respectively connected with output ends of a three-phase bus; the output ends of the plurality of to-be-positioned lines are respectively electrically connected in order with a three-phase voltage transformer and three high voltage switches; the system also comprises a controllable power supply respectively electrically connected with thethree high voltage switches, and a plurality of fault indicators respectively scattered on the plurality of to-be-positioned lines and respectively located behind the three high voltage switches; thecontrollable power supply can inject the current with a wide frequency and an adjustable amplitude into the three-phase bus; the injection process employs a frequency sweep method; the injection current can be set according to different power grid framework parameters; the current with the optimal injection characteristics is selected; aiming at the current with the optimal injection characteristics, the real time characteristic current value in each phase of the three-phase bus can be returned by the fault indicators, thus determining a fault area. Compared with the existing positioning mode, the power distribution network singlephase earth fault positioning method and system are higher in accuracy.

Description

technical field [0001] The invention belongs to the field of single-phase ground fault location of distribution network lines in a three-phase neutral point ungrounded system, and in particular relates to a single-phase ground fault location method and system of distribution network based on sweep frequency injection. Background technique [0002] The medium-voltage distribution network at home and abroad widely adopts the neutral point ungrounded or arc suppression coil grounded operation mode. Compared with the high-voltage transmission network, the medium-voltage distribution network has a high probability of failure, and single-phase ground faults occur frequently. When a single-phase fault is grounded, the non-fault phase-to-ground voltage rises, and the overvoltage may cause the ground fault to be transformed into a phase-to-phase short circuit fault, seriously endangering the system insulation and equipment safety, resulting in tripping and power supply interruption. ...

AI Technical Summary

Problems solved by technology

However, this method has the influence of the injection signal being limited by the capacity of the voltage transformer and the shunting of the distributed capacitance on the injection signal. For the distribution network line architecture with different parameter distributions, using this method will easily lead to failure of fault location.

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