A system level lifetime enhancement method for power converters of Type-4 wind turbines

This study proposes a new system level lifetime enhancement method for back-to-back connected power converters of Type-4 wind turbines. The method is based on swapping both the position and roles of MSC (machine side converter) and GSC (grid side converter) periodically at ultra low frequency with additional mechanical switches so that the lifetime consumption of electrical switches (IGBTs and diodes) is shared by the inverter and rectifier operating modes. Moreover, the aging effect of the semiconductors have been considered and tested as an additional evaluation. The proposed method is tested with PSCAD (for the simulation of wind turbine and converter system) and MATLAB (for the development of thermal models, loss calculation and lifetime calculations) tools. The results show the effectiveness of the proposed method with significantly increased lifetime values.