Estimation of the power electronic converter lifetime in fully rated converter wind turbine for onshore and offshore wind farms

A comparison has been made of the converter lifetime for a 3MW fully rated converter horizontal axis wind turbine located onshore and offshore. Simulated torque and speed of the turbine shaft were used to calculate voltage and current time series, that was used to calculate the junction temperatures of the diode and IGBT in the generator-side converter by a thermal-electrical model. A rainflow counting algorithm was applied to the junction temperature in combination with an empirical model of the lifetime estimation, to calculate the lifetime of the power electronic modules in the turbine. The number of parallel modules for each location to achieve 20 years life time has also been found. Simulations show the lifetime consumption rate of the diode and IGBT is decreased exponentially by increasing number of parallel modules, lowering the average temperature. The offshore wind turbine has a higher lifetime consumption rate, requiring a slightly higher converter rating to achieve a 20-year lifetime, but this difference is small, and both turbines will use the same number of modules.