External lightning protection system for wind turbine blades – further considerations

The installation of a lightning protection system for wind turbine blades has been adapted from other industries (i.e. building, aircraft) where a lightning down conductor is installed internally so as to preserve the aerodynamic performance of the blade. Having the down conductor internally within the blades would indeed preserve their aerodynamic performance. However the blades are, as a consequence, vulnerable to damage and burn resulting from lightning strikes. Owing to that, the authors believe that by having the down conductor on the external surface of the blade, the incidence of blade damage would be reduced. The authors have not found any literature in the public domain that quantifies the effect of having an external down conductor on the aerodynamic property. Hence, this aspect is being undertaken. Previous studies conducted by the authors were on two different arrangements. In one arrangement, a single 1 mm thick conductor was placed at 1m from the leading edge on the upper and lower parts of the blade. In the other arrangement, multiple conductors were placed at 1m intervals. The results from previous studies indicated that external down conductors affect the aerodynamic performance significantly but the first conductor (as encountered by the wind flow) appear to have the maximum influence. Hence, this paper addresses the question whether a single external down conductor could be deployed in an optimal position for least effect on the aerodynamic performance. The results show that the degradation on aerodynamic property is least at the trailing edge or the leading edge of the blade and these indicate that the installation of external down conductors may be viable in that region