A grounding fault judgment method and device based on wavelet analysis

Through a new first half-wave algorithm based on wavelet analysis, high-frequency interference is filtered out and transient and steady-state feature quantities are combined, the problem of distinguishing single-phase grounding faults in the prior art is solved, and accurate identification under high-resistance grounding and high-frequency disturbances is achieved.

CN114977077BActive Publication Date: 2025-07-22NANJING DAQO AUTOMATION TECH
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Patent Information

Application Number
CN202210597213.1
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2022-05-30
Publication Date
2025-07-22
Estimated Expiration
2042-05-30

AI Technical Summary

Technical Problem

In the prior art, when judging a single-phase grounding fault, especially in high-resistance grounding situations and high-frequency disturbances, it is difficult to accurately distinguish between inside and outside the zone.

Method used

A new first half-wave algorithm based on wavelet analysis is used to filter out high-frequency interference signals in zero-sequence voltage and zero-sequence current, combined with transient and steady-state characteristic quantities, the phase relationship between zero voltage and zero current is used to determine the position of the ground fault point.

Benefits of technology

It improves the accuracy of ground fault identification in high-resistance grounding and high-frequency disturbances, and can adapt to a variety of system operation modes and ground fault types, achieving rapid and accurate partitioning of intra- and out-of-zone ground faults.

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Abstract

The present invention discloses a grounding fault judgment method and device based on wavelet analysis, which relates to the technical field of distribution automation of power systems, and includes the following steps: performing wavelet analysis on the instantaneous value U of zero-sequence voltage 01 and the instantaneous value I of zero-sequence current 01 to obtain the filtered instantaneous value U0 of zero-sequence voltage and the filtered instantaneous value I0 of zero-sequence current, and then judging whether the effective value U of the filtered zero-sequence voltage 0T > the setting value U of zero-sequence voltage 0SET and the effective value I of zero-sequence current 0T > the setting value I of zero-sequence current 0SET are both satisfied to determine whether there is a grounding fault, and then judging whether it is an in-zone grounding fault or an out-of-zone grounding fault through the results of transient analysis and steady-state analysis. The main advantage of this algorithm is that it can use wavelet analysis to filter out the interference signals entering the AD sampling chip in the FTU, and then use the filtered zero voltage and zero current for fault identification, and can adapt to various system operation modes such as ungrounded neutral point, arc suppression coil grounded neutral point, and small resistance grounded neutral point.
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