This paper mainly introduces the distribution law and characteristics of capacitive current when single-phase grounding occurs in the high-voltage power supply network underground in coal mines,as well as the basic principle and application status of leakage protection in coal mine underground power grids.It summarizes the current technical drawbacks.A new type of leakage protection method for underground high-voltage power grids in coal mines is proposed based on on-site engineering practice.This method uses injection of diagnostic current signals and internal protectors of switches,and uses algorithms to detect diagnostic signals in a dispersed manner to identify and protect faulty power lines in the power grid.It compensates for the shortcomings of traditional leakage protection in detecting grounding lines through zero sequence current,improves the accuracy of high-voltage leakage protection in coal mines,and ensures the safety of underground power supply.
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