Simulation Study of Lightning Transient Overvoltage on Wind Turbine in Mongolia under Different Grounding Cases

In this paper, we presented real wind turbine model using the circuit simulator PSCAD/EMTDC to investigate the lightning transient grounding potential rise generating in wind turbine/kiosk earthing system and electrical devices under the different grounding cases. The influence of lightning current waveshape and grounding characteristics on the wind turbine lightning overvoltage have been conducted. The simulation result shows that the probable of peak current with 31 kA could produce 350 kV potential rise in case of Rt = 9.3 Ω and Rk = 1.5 Ω. In case of Rt = 2.3 Ω and Rk = 2.3 Ω, the potential rise on the main grounding bus bar is possible to reduce 170 kV, transient voltage on the low voltage terminal of power transformer reduced to approximately 40%. Double peaked waveshape gives oscillation compare with standard 2.6/50 μs waveform. Moreover, the grounding cable(PE) has shown negative impact during the lightning transient phenomena.