Loss comparison of matrix and back-to-back converters for offshore WECS

Abstract

In this paper is presented a wind park layout of series-connected wind turbines. The wind energy conversion system (WECS) inside the nacelle is described and the main technical challenges presented by this wind park topology are briefly discussed. The WECS requires a full scale AC-AC converter as the generator is a Permanent Magnet (PM) synchronous machine. The matrix converter is an interesting candidate for offshore applications because it is compact and reliable as it does not feature the DC link capacitor which is required by the conventional back-to-back (B2B) converter. Performance of the matrix converter in terms of efficiency is the object of this paper. Losses of both direct and indirect matrix converter are assessed by simulation and compared with those of the B2B converter showing that the matrix converter performs better. Different switch implementations are also included in the comparison: single high rating IGBTs and diodes or series and parallel connections of low rating IGBTs and diodes and Reverse Blocking IGBTs. The series and parallel connection of low rating IGBTs and diodes is found to perform superiorly.