Harmonics Reduction in a Wind Energy Conversion System with a Permanent Magnet Synchronous Generator

Abstract

This paper is mainly doing simulation using Matlab to filter harmonics which are found in a Permanent Magnet Synchronous Generator (PMSG) Wind Energy Conversion System (WECS) connected to a three-phase load through a full converter (AC/DC/AC). Harmonics are caused by the converter system. To reduce these harmonics, an effective filter is needed. There are two types of filters that are usually used, active and passive filters. Among the types of passive filters are band pass which block lower harmonics orders such as 5^th, 7^th, 11^th, and 13^th, and high pass filters which are responsible to filter higher harmonics such as 24^th. So, we use two stages of harmonic filtering. The first stage includes a c- type high pass filter (for lower orders), a double – tuned filter (for 11^th and 13^th) and high pass filter (for higher orders). Secondly, this stage includes a single – tuned filter instead of C- type filter with keeping the other filters. We applied Fast Fourier Transform (FFT) to determine the harmonics and purposes. In this thesis, we investigate and analyse the level of harmonic content of two AC/DC converters working at different wind speeds. Our findings indicate significant improvements in Total Harmonic Distortion (THD) with best results in the second method.