Key issues with lightning protection research of the large-scale wind farms

The paper summarized the advances and research fronts regarding lightning protection of the wind farms, for which the following aspects were included: the field observation of lightning strikes to wind farms and long air gaps experiments, the physical mechanism of the lightning attachment process, the lightning risk assessment and optimal design of the lightning protection system (LPS), the damage mechanism of wind turbine blade due to the lightning strikes, the electromagnetic transient effect inside wind turbines and the protection methodology, the testing technology for wind turbine LPS, as well as the new challenges for offshore wind farms. Based on the above analysis, five key issues were proposed for future investigations, namely, the rotation effect of wind turbines on distribution of the space charge, the polarity effect of lightning attachment and the physical model of negative leader propagation, the physical mechanism of multiple upward leaders inception and the lightning shielding effect of the wind farms, the damage mechanism of wind turbine blades due to lightning strikes and the dynamic modelling of the blade explosion effect, and the lightning risk assessment and testing methodology for wind turbines. Appropriate addressing of these pending issues will further improve understanding of the lightning physics with wind farms, and also provide feasible and efficient routes to achieve optimal design of the lightning protection system for wind turbine blades.