Windfarm earthing

A windfarm earthing system is normally large when compared to an earthing system typically used in a transmission or distribution substation. The performance of large earthing systems subject to an injection of power system frequency or transient current can differ to the response expected from a smaller system. Typical methods used to design the earthing system of a substation may not be applicable for use on a windfarm. Any earthing system must be designed to meet a number of requirements. Some of the factors that have to be accounted for when designing an earthing system to satisfy all such requirements for windfarms include the windfarm soil resistivity, the power system earth fault level at each wind turbine, the operating speed of the power system protection and the level of lightning protection required. A number of these are discussed in this paper