Impact of wind conditions on thermal loading of PMSG wind turbine power converters

Abstract

Power converter reliability is critical for permanent magnet synchronous generator (PMSG) wind turbines. Converter failures are linked to power module thermal loading but studies often neglect turbine dynamics, control and the impact of wind speed sampling rate on lifetime estimation. This study addresses this using a 2 MW direct-drive PMSG wind turbine model with a two-level converter, and simulating junction temperatures (Tj) using a power module thermal equivalent circuit under various synthetic wind speed conditions. These synthetic wind conditions include constant and square wave profiles representing stable and gusty wind conditions. Responses to square wave wind speeds showed that the lower the gust frequency, the higher ΔTj becomes, demonstrating that low turbulence sites have greater thermal variation in the converter. In contrast, wind speed variations with frequencies >0.25 Hz deliver only small increases in ΔTj. It is concluded that reasonable approximations of Tj profiles can be made with 0.25 Hz wind speed data, but that lower data rate wind measurements miss essential, damaging characteristics.