PSCAD Simulation Research of Fault of Voltage Transformer of Coal Mine Power Network

The burning out of voltage transformer happens occasionally in coal mine power network because of single-phase grounded fault. According to equivalent model of single-phase grounded fault of power network, simulation analysis was presented on the transient characteristics of the primary side current of PT in the paper. It was considered that the causation of fault of PT is large single phase-toground capacitive current in coal mine power network. And a group of voltage transformer in 6 kV distribution system was simulated based on PSCAD/EMTDC. Three kinds of eliminating resonance method in different condition were compared including connecting a nonlinear resistance to neutral point of high voltage side of three-phase PT, connecting a damping resistance to the secondary assistant windings of three-phase PT, grouding neutral point through arc suppression coil. At last the paper indicated that neutral grounded by arc extinction coil is the best solution of single-phase grounding fault in coal mine(power network.