Method and system for identifying high-resistance faults of substation low-voltage ac system

By combining variational mode decomposition and skewness criterion, the residual current mutation characteristics of the substation low-voltage AC system are extracted, solving the problem of high-resistance fault identification, achieving high-sensitivity and low-false-judgment fault identification, and ensuring reliable power supply of station power and safe and stable operation of the substation.

CN122307218APending Publication Date: 2026-06-30POWER RES INST OF STATE GRID SHAANXI ELECTRIC POWER CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
POWER RES INST OF STATE GRID SHAANXI ELECTRIC POWER CO LTD
Filing Date
2026-03-27
Publication Date
2026-06-30

AI Technical Summary

Technical Problem

Existing technologies are insufficient to effectively identify high-resistance faults in low-voltage AC systems used in substations, especially when measurement quantities are limited, interference is complex, and faults are weak and irregular. Traditional methods suffer from missed detections and misjudgments.

Method used

The variational mode decomposition algorithm is used to extract features of residual current mutations. Combined with the skewness criterion, frequency structure features are constructed to distinguish between high-frequency and low-frequency modes, thereby achieving effective differentiation of arc grounding faults, power electronic equipment access, and system disturbances.

Benefits of technology

It significantly improves the sensitivity and accuracy of high-resistance fault identification, reduces the risk of misjudgment and missed detection, adapts to changes in on-site working conditions, and has good engineering deployability and rapid detection capabilities.

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Abstract

This invention discloses a method and system for identifying high-resistance faults in a substation low-voltage AC system. The method involves collecting the residual voltage and current of each line in the substation's low-voltage AC system, constructing residual voltage and current abrupt changes, triggering detection, and then performing variational mode decomposition on the abrupt change signals over three cycles. This decomposes the original signal into several intrinsic mode components, further calculating the center frequency of each mode, and classifying each mode according to the magnitude of the center frequency, thereby distinguishing between low-frequency and high-frequency modes. Based on the high-frequency and low-frequency modes, the method calculates the instantaneous frequency fluctuation index of the high-frequency mode and the amplitude enhancement index of the low-frequency mode. A frequency structure feature quantity is constructed based on these two indicators. The frequency structure feature quantity is compared with a preset threshold; if the corresponding criteria are met, the fault is determined to be an arc grounding fault, a power electronic equipment connection, or a system disturbance, and the corresponding detection result is output.
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