Research On Selectivity Leakage Protection For Underground Low Voltage Distribution Network

Currently,leakage downground has become the main fault in the coal power supply system, leakage may not only lead to electric shock accidents for staff , and even may form single-phase short circuit earth-fault, which thereby expanding short-circuit accidents of two phase, and generates electric rods to cause gas explosion underground and other serious accidents. Leakage protection device is such a kind of protection device that it can prevent personal casualty by electric shock and gas explosion caused by leakage faults, which assembles in power supply network, and it is indispensable no matter whether in underground or upground, its application is very extensive.The condition of leakage accident in low-voltage power supply network is analyzed in the paper, based on which and the simulation result, a new kind of selective leakage protection system is put forward. In this system TMS320F2812 is selected as core processor, "three-stage leakage location method" is used as an option for leakage circuit, which means the triple judgment including zero sequence directional power detection,additional dc power test and zero sequence current group amplitude is all used , to realize comprehensive judgments of in many sets of leakage protection devices networked in the overall power grid, and thus to rapidly acknowledge leakage circuit, in order to achieve the correct choice of leakage circuit.