Lifetime Evaluation of IGBT Module in DFIG Considering Wind Turbulence and Nonlinear Damage Accumulation Effect

The insulated-gate bipolar transistor (IGBT) is the weakest component in wind power system, of which lifetime mainly relies on its operation environment, especially for those in generator side of wind turbine where higher failure rate is expected, resulted from fluctuation of wind speed greatly. However, in most literatures, wind speed is just simplified as constant value, and then linear accumulation method is applied to evaluate the life of IGBT module in different wind farms, hardly obtain the relationship between wind speed distribution and lifetime consumption of IGBT module, let alone pertinent thermal lifetime management strategies. Therefore, in the paper, a probabilistic lifetime evaluation model of IGBT module in generator side (GSI) of doubly fed induction generator (DFIG) considering wind turbulence and nonlinear damage accumulation effect is proposed. Firstly, approach to calculate the mean time to failure (MTTF) of IGBT module based on nonlinear damage accumulation is presented; then, a probabilistic lifetime evaluation model is built and relationship between wind speed probability and lifetime consumption of GSI in three commercial wind plants is also analyzed. Furthermore, thermal lifetime extension measures are proposed based on the built multi-scale zones life evaluation model. Results indicate that the largest destructive point is close to synchronous wind speed, and the vulnerable zone of wind speed range is that higher than synchronous wind speed, with small probability density on the contrary. Based on the conclusion, new methods to extend lifetime of IGBT module in generator side converter (GSC) are presented through a case study, as well as validation of the proposed strategies.