Mitigation of Transient Overvoltages under Lightning in Networks with Wind Farms Connection using MOV Surge Arresters

The effectiveness of surge arresters to mitigate transient overvoltages in Wind power plant (WPP) located in areas with high lightning activity and high soil resistivity is investigated in this paper. WPP is dispersed over large areas of land with several hundred metres of overhead lines and underground cables. However, the insulations of the WPP components are exposed to severe overvoltage stress when lightning strikes the overhead lines and propagates through the WPP cable networks. These overvoltages can damage the surge arresters being used to protect WPP cable network and other components if the ground resistance is relatively high. The ground resistance can be reduced significantly in areas with high soil resistivity but at a high financial cost. EMTP was used to analyse the effects of lightning surge at different ground resistances at the WPP towers. The results show that the energy absorbed by the arresters increase with higher ground resistance.