Discontinuous-Modulation-Based Active Thermal Control of Power Electronic Modules in Wind Farms

With the increasing renewable energy injected into the electrical distribution grid, the reliability of the power converter is gaining importance for the power system. In order to address the wear-out caused failure mechanisms of power semiconductors and thereby increasing the reliability, this paper aims at balancing the thermal stress caused during operation between different power converters in a wind park. An active thermal control strategy based on the discontinuous pulsewidth modulation is proposed for reducing the thermal stress of the semiconductors under a fluctuating power profile, while maintaining good power quality. The proposed method is introduced for multiple converters, which are connected to the same grid feeder and its impact on the lifetime of the semiconductors is investigated analytically. Finally, the effectiveness of the proposed method is experimentally validated for a two-level voltage source converter.