Single-phase ground high-resistance fault identification method and system suitable for new energy access flexible direct current network system

By using adaptive negative sequence reactors and in-phase section identification criteria, the problem of identifying single-phase grounding high-resistance faults in new energy access flexible DC grid systems has been solved, enabling reliable fault identification under communication interruption conditions and improving the sensitivity and selectivity of protection equipment.

CN122307245APending Publication Date: 2026-06-30TIANJIN UNIV +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
TIANJIN UNIV
Filing Date
2026-04-03
Publication Date
2026-06-30

AI Technical Summary

Technical Problem

In the flexible DC grid connection system for new energy sources, traditional relay protection equipment is difficult to effectively identify single-phase grounding high-resistance faults when communication is interrupted or optical cables are broken, resulting in reduced protection sensitivity, failure to operate or false operation, which makes it difficult to meet the requirements of reliability and sensitivity of fault identification in the independent power transmission network of power electronics.

Method used

By employing an adaptive negative sequence reactor combined with the phase angle ratio of the fault phase voltage and negative sequence current components, and through the identification criteria of the same phase section and the fuzzy zone sign function, the protection action equation is adaptively switched to achieve reliable identification of single-phase grounding high resistance faults inside and outside the zone, thereby improving protection sensitivity and resistance to transition resistance.

Benefits of technology

In communication interruption scenarios, faults can be reliably identified using only single-end electrical information, avoiding failure to operate and false operation, improving the sensitivity and selectivity of protection, and ensuring the power supply reliability of the new energy transmission grid.

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Abstract

This invention discloses a method and system for identifying single-phase grounding high-resistivity faults in new energy grids connected to flexible DC power grids. The method involves acquiring three-phase time-domain voltage and current signals, obtaining phasors through discrete Fourier transform, decomposing them into sequence components, and extracting the fault phase voltage and current phasors. Based on the fault phase voltage phasors and negative-sequence current components, and combining a sign function with a fuzzy region, an identification criterion for the same-phase section is calculated to identify the lead-lag state between the bus voltage and the fault point voltage. Based on the criterion results, the protection action equations are adaptively switched, and the adaptive negative-sequence reactor operating voltage is calculated using the fault phase electrical quantities and the set impedance. This completes the reliable identification of single-phase grounding high-resistivity faults both within and outside the protection zone. Compared with existing technologies, this invention solves the problem of difficult high-resistivity fault identification in power electronic grids and achieves reliable identification of high-resistivity faults both within and outside the protection zone.
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