METHOD OF PROTECTING A CONVERTER OF A WIND TURBINE AND PROTECTION SYSTEM

A method of protecting a converter (110) of a wind turbine and a respective protection system are provided. The converter (110) is coupled to a generator (20) of the wind turbine to perform conversion of electrical power produced by the generator, the converter (110) comprising plural semiconductor components (150) that are operational to provide the conversion of the electrical power. The method includes the performing of a step of estimating a junction temperature (Tj) of at least one of said semiconductor components (150) by determining a current (I1, I2, I3) in the converter (110) associated with power loss in one or more of the semiconductor components (150); estimating power loss (PL) associated with the one or more semiconductor components (150) based on the determined current and on a state (sw) of the one or more semiconductor components; and using a thermal model (600, 700) of the one or more semiconductor components (150) to estimate the junction temperature (Tj) of at least one of the one or more semiconductor components (150) based on the estimated power loss (PL). The estimating step is repeatedly performed.