Converter Monitoring Unit for Retrofit of Wind Power Converters

A converter monitoring unit (CMU), which will enable condition monitoring of wind turbine converters is presented in this paper. Reducing the cost of corrective maintenance by means of condition monitoring is a way of lowering operation and maintenance costs for wind turbine systems. The CMU must be able to detect a broad range of failure modes related to Insulated Gate Bipolar Transistor (IGBT) power modules and associated gate drives. IGBT collector-emitter on-state voltage (vceon) and current (ic) is sampled in the CMU and used for detection of emerging failures. A new method for compensation of unwanted inductive voltage drop in the vceonmeasurement path is presented, enabling retrofitting of CMUs in existing wind turbines. Finally, experimental results obtained on a prototype CMU are presented. Experimentally the vceondependency to IGBT junction temperature and deterioration of gate drive voltage is investigated. The proposed method shows good detectability of both thermally related degradations of the power module and detectability of deterioration of gate drive voltage. It is also expected that the proposed method will enable detectability of other failure mechanisms.