الفهرس 
1. INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This thesis investigates lightning protection for wind farms as it is used for keeping the farm continual service. The investigation is carried out concerning the strokes hitting the turbine blades and the corresponding backflow currents. A blade tip section is designed and experimentally implemented in order to evaluate the lightning protection systems reported in IEC-61400-24 standard. The lightning attachment manner to the blade is examined using standard lightning impulse voltages (positive and negative) for polluted and unpolluted blade surfaces. Two of the tested standard protection systems are improved for restricting blade punctures. Also, the experimental comparisons are exploited to propose a lightning protection system that is examined experimentally. The surge propagation is evaluated through simple wind farm consisting of ten wind turbines when the lightning hits a blade. Towards appropriate transient analyses, high frequency models of the wind farm components are developed. Identification parameters of the low voltage (LV) surge arrester model are introduced. Backflow current-overvoltages are evaluated concerning different transformer and grounding system models. The grounding system is modified to reduce these overvoltages. The surge arresters burnout is examined in order to verify this modification with considering different factors of lightning stroke inception angles, in service and out of service wind farms, and wind farm sizes. Generally, this thesis is contributing in producing reliable lightning protection system for the wind turbine blades and also in mitigating the backflow current-overvoltages using high frequency-based accurate simulated wind farm.