A practical approach to determining lightning risk for Wind Turbine Generators as per IEC 61400-24

Abstract:
Lightning strikes to tall structures pose a safety risk to personnel, as well as risk of damage to electrical equipment located within the structure. Wind Turbine Generators (WTGs), which are naturally tall structures, are frequently subjected to lightning strikes, often resulting in damage to the turbine and its equipment. As per IEC 61400-24, it is required that WTGs are manufactured with an integrated Lightning Protection System (LPS) to minimum Lightning Protection Level I (LPL I). It is, however, not always clear to engineers, designers, and operators that such an LPS, although being inte-grated, has a limited lifespan, and requires preventative maintenance. To determine the frequency of maintenance, a lightning risk analysis could be useful, if conducted correctly. It is com-monly seen that incorrect standards for determining the frequency of lightning events are used in calculation, such as standards for buildings, resulting in a misrepresented expectation for frequency of lightning strikes and incorrect selection of the maintenance intervals. Failure to monitor and conduct maintenance to the LPS could result in damage or catastrophic failure of the WTG as a result of lightning.