A new scheme of selective leakage protection of mine low-voltage power network based on differential variable of zero-sequence current

In allusion to low reliability and sensitivity of existing selective leakage protection devices used in mine low-voltage power network, a new scheme of selective leakage protection was proposed which was based on differential variable of zero-sequence current. In the scheme, differential variable of zero-sequence current is gotten at different measured points in each branch when single-phase leakage fault occurred in mine low-voltage power network. Lateral selectivity and fault section location of leakage protection are achieved according to differences of amplitude and phase of the differential variable between fault branch and normal branch. Simulation via Matlab/Simulink and calculation via Fast Fourier caused by Transform show that the scheme avoids influences by load capacity and initial phase angle of voltage of from power network and has high reliability and sensitivity of fault line selection and section location.