Coupled field, circuit and mechanical modelling of wind-turbine

Purpose - To identify interactions existing between electromagnetic, electric and mechanical phenomena in variable speed permanent generator wind-turbines and propose a methodology enabling oscillations analysis. Design/methodology/approach - Evaluation of the accuracy of alternative approaches such as traditional fundamental and higher harmonic representation as well as coupled field, circuit and mechanical techniques based on the finite element method to represent such phenomena. Findings - Low frequency oscillations observed experimentally necessitate strong coupling between electromagnetic, electrical and mechanical phenomena. Research limitations/implications - The techniques adopted are limited to two-dimensional configurations, while possible three-dimensional air-gap eccentricity is not considered. Practical implications - Special consideration should be paid by the wind turbine controller to attenuate the studied oscillations. Originality/value - Development of an adequate modelling methodology enabling consideration of low frequency oscillations.