Analysis of transient overvoltage phenomena due to direct lightning strikes on wind turbine blade

The paper deals with transient overvoltage analysis of wind turbines under lightning strikes; with particular emphasis on low voltage surge mitigation, using metal oxide surge arresters. Lightning protection of modern wind turbines involves equipping the blades with metal receptors and internal down-conductors. However, there is still uncertainty in the behavior of such system under lightning strikes, specifically on wind turbines located in areas with high keraunic levels and high soil resistivity. The Electromagnetic Transient ProgramAlternative Transient Program (EMTP-ATP) software package was used to model a section of an existing wind farm, as a test system under lightning strikes; to determine the transient voltage develops at the top of the stricken tower and propagates to the low-voltage network of nearby turbines, when a wind turbine´ blade is struck by lightning. The results show that low voltage surge arresters are necessary in wind turbines, in reducing transient overvoltages in the low voltage network.