Converter monitoring in a wind turbine application

Two Converter Monitoring Units (CMU) which were retrofitted in a multi Mega Watt wind turbine converter are presented. Synchronized sampling of semiconductor voltage (vce_on) and semiconductor current (i_c) enables the condition monitoring of the power modules. A vce_on measurement circuitry for field operation is presented. A novel method of numerical integration of Rogowski coil voltage enables current sensing. Data from a whole year of operation show that the presented methods are consistent throughout long term operation, and that both the measurement principles and reference functions (model) are consistent during long time operation. It is thus expected that degradation of power modules and gate drives can be monitored.