Effects of Wind Turbine Grounding System Interconnection on Electromagnetic Transients Caused by Lightning

The latest edition of the norm IEC-61400-24 recommends that the wind turbine’s grounding system should be interconnected to the other wind turbine’s grounding system erected in the wind park; this is in order to reduce abnormal earth potential distribution and mitigate dangerous overvoltages. Based on this statement, an analysis of the effects on transient current and voltage during lightning attachment is conducted.
A comparison between a stand-alone wind turbine (without grounding system interconnection) and a set of interconnected wind turbines (with grounding system interconnection) is presented and analyzed. Overvoltage and overcurrent in form of surges may be the result of electromagnetic traveling waves caused by lightning; these effects may impose additional requirements for the reliable operation of the low voltage and medium voltage grid against surges caused by lightning strikes.