A PWM Current-Source Converter-Based Wind Energy Conversion System

Current-source converters (CSCs) are a good candidate for the series-connected wind energy conversion system (WECS). However, the existing CSCs either exhibit poor generator stator current harmonics, require bulky low-frequency transformers, are limited in their application to synchronous generator-based wind systems, or necessitate complicated modulation and commutation. In this work, a new CSC is proposed and investigated. It features a unique hybrid structure consisting of a modular medium-frequency transformer-based voltage-source converter on the generator side and a conventional CSC on the grid side. The proposed converter offers superior generator stator current harmonics performance, a smaller size, simplified modulation and commutation schemes, and suitability for both synchronous and induction generator-based wind systems compared with the existing converters. In addition, all the advantages of the existing CSC-based WECS are retained. The proposed converter is discussed and analyzed, its control scheme is introduced, and its performance is investigated by both simulations and experiments.