Far Field Region of Radiated Emissions from Wind Energy Conversion Systems

Wind energy conversion systems (WECS) or wind turbines (WTs), respectively, radiate electromagnetic (EM) emissions unintentionally. In order to ensure that radio broadcasting services or terrestrial navigation systems are not disturbed by WTs, the radiated EM emissions have to be measured and assessed in the CISPR Bands A to D (from 9 kHz to 1 GHz) according to the corresponding standards. Due to the enormous size of a WT, it seem to be reasonable to evaluate, whether the emission measurement is be carried out in the far field region. For this reason, numerical field calculations are carried out by means of an simplified WT model. It points out, that far field region of the radiated emissions is not located in the standardized measurement distance of 30 m, but a distance of more than 3 km with respect to the WT. Assuming that a real world WT behaves similarly than simulation model used for the numerical field calculations, the measuring locations defined in the corresponding standards are only conditionally suitable for electrical large radiators like wind turbines.