Experimental investigation of the electrification of wind turbine blades in fair-weather and artificial charge-compensation to mitigate the effects

Abstract

Wind turbines are tall structures immersed in the electrified Earth's atmosphere. Even in fair-weather, a modern wind turbine can be subjected to several tens of kilovolts of atmospheric potential. In this work, we conduct two series of experiments to investigate the expected electrification of wind turbine blades in fair-weather conditions, as well as the possibility of mitigating this electrification using an artificial charge-compensation system. The first set of experiments is conducted in the laboratory, using a real wind turbine blade tip in a configuration whose down conductor is electrically isolated from the rest of the system. Under the influence of an atmospheric electric field, the isolated blade tip polarizes. Two main timescales are identified: a fast mechanism attributed to the polarization of the blade down conductor and a slow mechanism attributed to charge accumulation on the insulating blade's glass fiber exterior. The second set of experiments is conducted in the field and uses vertical wires lifted by a multirotor drone. In these experiments, it was shown that a vertical isolated wire of 100 m reached a potential of more than 5 kV due to the effects of the fair-weather electricity. In both sets of experiments, an artificial charge-compensation system is tested to explore the possibility of mitigating blade electrification. It is proposed that charge control of wind turbine blades may mitigate the electrostatic discharge typically observed at the root and tips of the blades.