Power distribution networksingle-phase grounding fault handling method based on dual-mode function

Abstract

The invention provides a power distribution networksingle-phase grounding fault handling method based on a dual-mode function, and belongs to the technical field of powerdistribution automation. The technical scheme is mainly suitable for a delaylow-resistanceinputgrounding mode of a neutral point, and can be compatible with grounding modessuch as non-grounding of the neutral point, grounding of the neutral point through an arc suppression coil and grounding of the neutral point through low resistance. According to the scheme, a transientpower direction protection / grounding overcurrent protection dual-mode function is deployed for a first-stage section switch of a 10kV outgoing line of a transformer substation, thetransientpower direction protection / grounding overcurrent protection dual-mode function or a voltage-time type feeder automation function is deployed for a later-stage section switch, and when grounding faults occur, rapid handling of single-phase grounding faults is realizedby logic cooperation of all stages of switches.

Description

technical field [0001] The invention relates to the technical field of distribution automation, in particular to a method for processing a single-phase grounding fault of a distribution network based on a dual-mode function. [0002] technical background [0003] Distribution network faults are the main factor causing power outages for users, and single-phase ground faults account for more than 80% of all faults in distribution lines. Based on factors such as personal safety, equipment safety, and power supply reliability, some internationally advanced regions have realized line selection and nearby rapid isolation of permanent single-phase ground faults. The latest "Technical Guidelines for Distribution Networks" promulgated by the State Grid Corporation of China clearly states that for the neutral point ungrounded and arc suppression coil grounded systems, after a permanent ground fault occurs, it should be handled according to the principle of rapid and nearby fault isolat...

AI Technical Summary

Problems solved by technology

For systems whose neutral point is grounded via an arc-suppression coil or whose neutral point is not grounded, the steady-state characteristics are not obvious after a single-phase ground fault, and it is technically difficult to use steady-state quantities for fault detection. Theoretically, the transient power direction method can Fault detection is realized, but the principle is relatively complicated, and the technical principle and performance requirements of the measurement and control device are relatively high, which is still a difficulty in engineering practice

For the neutral point grounding system through a small resistance, the principle of single-phase ground fault judgment is relatively simple, and the difficulty of technical implementation is relatively low, so the judgment accuracy for most single-phase ground faults is relatively high, but the ability of this scheme to withstand transition resistance is weak. According to calculations, when the grounding overcurrent setting is 40A, the transition resistance of the small resistance grounding system is only about 150Ω, which is not conducive to the realization of high-resistance ground fault protection. about 15%

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