Field-measurement based hygrothermal modelling of the converter-cabinet climate in wind turbines

Power converters in wind turbines suffer from frequent failures. Root-cause analyses point to environmental influences as important drivers of converter failure. Based on comprehensive field measurements in wind turbines, we derive hygrothermal models describing the dependence of temperature and humidity in the converter cabinet on the ambient climatic conditions and turbine operation. The results show that lumped-parameters models of minimal complexity are suitable for describing the conditions with reasonable accuracy and that publicly available ERA5 reanalysis data may be used to consider the site-specific climatic conditions outside of the wind turbine. In addition, we demonstrate that the hygrothermal model derived for a turbine type can successfully be transferred to identical turbines operating in other countries. The models can therefore serve as a basis for refined requirement specifications as well as for the derivation of application-specific test procedures for power converters and their components.