Fusion fault line selection method of small current grounding fault based on VMD

Abstract

At present, the fault line selection method of coal mine distribution network has the problem of fault line selection failure when the relevant fault features are not obvious. The fault line selection method based on single modal component and single fault feature has low accuracy. In order to solve the above problems, a method of small current grounding fusion fault line selection based on variational mode decomposition (VMD) is proposed. VMD is used to decompose the fault zero-sequence current of each outgoing line in the bus into multiple modal components. The layer number of the VMD is determined according to the fault features of the modal components. The modal components with obvious fault features are selected as effective modal components for fault line selection. The transient energy and the waveform similarity of the effective modal component of the zero sequence current of each outgoing line fault are calculated respectively. According to the proportion of transient energy and the proportion of waveform similarity of effective modal components of each outgoing line, a fault line selection criterion based on transient energy and a fault line selection criterion based on waveform similarity are constructed. The two fault line selection criteria are fused to form a fault fusion line selection algorithm based on VMD. A coal mine distribution network model is built by using the electromagnetic transient simulation software ATP/EMTP. The proposed fusion fault line selection method is verified under single-phase-to-ground fault scenarios with different ground fault resistances, fault initial phase angles and fault locations. The results show that when various single-phase ground faults occur in the distribution network, the fusion line selection method of small-current grounding fault based on VMD is not affected by the fault location. The fault line selection accuracy is respectively improved by 17% and 50% compared with the energy method and the correlation clustering method. The fusion line selection method is not affected by the fault type, and can be applied to the small current grounding fault line selection.

Keywords

• coal mine distribution network
• small current grounding system
• fusion fault line selection
• variational mode decomposition
• high-frequency oscillation component
• modal component
• transient energy
• waveform similarity