When the project application was submitted in 2008 there were several research project at SINTEF Energy Research related to offshore wind, most of them associated with NOWITECH. However no projects had main focus on important converter basic characteristics such as reliability, efficiency and control problems related to converters interacting with complex grid systems. These are all crucial issues for offshore wind power conversion systems due to remote locations and harsh environment.
The main results from the project are summarized as follows:
- Detailed converter simulation models for testing control algorithms, component losses, thermal cycling etc.
- Loss models with input from measurements and output to life time estimators. Mainly for IGBTs but also for inductive components (winding losses)
- Multi-physics analysis (electric, thermal, mechanical) of IGBT stress – PhD student Tilo Poller
Laboratory equipment provided by the project and experiments:
- High Voltage Test Cell for Measurements of IGBT temperature dependent switching losses
for input to simulations
- Power Cycling Tester for life-time testing of high-power IGBTs – Input to life-time prediction
- Several PWM Voltage Source Converters in the range of 50 kW with advanced digital control algorithms for generator side and motor side operation and currently used in the SINTEF/ NTNU Renewable Energy Systems and Smart Grid Laboratory
- Case 1 and case 2 simulations of control algorithms, loss calculation and thermal stress
- Analysis of Converters Topologies for DC series connected wind turbines
Achievements within control strategies and algorithms:
- Algorithm for IGBT power cycling lifetime prediction for Wind Power converters
- Algorithms for AC side droop control, virtual synchronous machine etc.
- Control strategies for parallel converters based on AC droop
Post Doc work by Salvatore D'Arco on topologies and control strategies completed.
Well established cooperation with TU Chemnitz on power semiconductor reliability.