A simplified algorithm for predicting power cycling lifetime in Direct Drive wind power systems

Direct Drive (DD) Wind Energy Conversion Systems (WECS) represent a valid alternative to more conventional geared configurations for increasing efficiency and reliability. However, DD WECS can operate at lower electrical frequencies and be more susceptible to power cycling stress that ultimately affects the lifetime of power electronics converters. An accurate prediction of power converters lifetime in a DD WECS can involve complex and time consuming simulations. The paper analyzes the power cycling lifetime and introduces a simplified procedure to reduce the computational complexity. The procedure refers to a two level back to back topology with standard IGBT modules but can be easily extended to other configurations. A numerical example is reported with wind data measured on a wind farm in mid Norway.