A comprehensive lightning surge analysis in offshore wind farm

Abstract

The structure of offshore wind farm is completely different from that onshore, and it is threatened by intruding lightning surge from various routes. Little attention has been paid to the electric equipment installed on offshore power station so far. A comprehensive lightning surge analysis for offshore wind farm is investigated in this paper. The detailed model of electric equipment in the system is firstly developed, including the transmission tower, the power station, the wind turbine and so on. The supporting structure and the platform of offshore power station are then modelled based on method of partial element equivalent circuit. Considering three lightning strike scenarios, the overvoltages at critical nodes of the system are obtained, the mechanism for lightning surge characteristics within the farm are elucidated, the influence of submarine cable length on the transient overvoltage is discussed, and two surge arrester schemes have been proposed. The results indicate that the surge originating from onshore overhead line is the most serious situation. The submarine cable is beneficial to the lightning protection, and the incoming surge onshore decreases remarkably as the cable length increases. Surge arrester configuration needs to be adjusted based on the scale and the topology the system.