A Study of Current Waveforms Distortion of Doubly-fed Generator for Wind Turbine Application by Space Higher Harmonic

Abstract

This paper describes a method to analyze higher harmonic currents resulting from higher space harmonics, depending on the winding pattern of a doubly-fed generator. A 1.5-MW generator was used for the analysis, and the results are compared using finite element magnetic field analysis and measurements.
The results revealed that the proposed analysis, which focuses on the winding pattern and takes into account higher space harmonics, allows us to calculate higher harmonic currents at high precision, understand the mechanism of changing higher harmonic currents due to the slip or the load of the generator and considerably reduce higher harmonic currents at the armature by restricting higher harmonic currents at the magnetic field. In addition, the sensitivity analysis of design parameters clarified the relationship between current distortion and basic characteristics on electric designs.