Study On Single-phase Earth Fault Line Selection Of Underground High-voltage Grid In Coal Mine Based On Network

The zero-sequence current between fault line and normal line is quite different especially in thetransient process after single-phase earth fault occurred, according to which the equivalent circuit ofcoal mine HV grid is built to get the expressions of zero-sequence current and find the differencebetween fault line and normal line. It is analyzed and proved by theoretical derivation in the paperthat there is on transient pulse in the zero-sequence current, and can be used to select the fault line bythe amplitude and polarity of the pulse. Two methods according to the transient pulse characteristicis introduced to select fault line, which are called direct selection method and break-variableselection method respectively. Furthermore, the fault line selection method based on the DCcomponent of zero-sequence current is introduced to solve the problem that the transient pulse willnot be obvious when fault angle is small. In order to select the fault line correctly, the compositionand implementation of coal mine high-voltage (HV) grid base on network is introduced, taking onepractical renovation project as example. Finally the combination mechanism of line selectionmethods based on network is introduced in the paper, to judge the reliability and correctness of theselection result.