Power Electronics for Reliable and Energy efficient Renewable Energy Systems

The research project has now been completed. Several milestones have been achieved in the process for establishing tools, algorithms etc. for providing efficient and reliable offshore conversion systems. These tools utilize the combination of component modelling, laboratory experiments and numerical simulations. *Component modelling: - 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 - Power Cycling Tester for life-time testing of IGBT single chips - 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 Smart Grid Laboratory *Case simulations - 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 - Researcher and student exchange program also with support from the German DAAD program - Test methodologies and test equipment *Competence building for the SINTEF staff and students on all planned activities - The SINTEF staff is well prepared for continuing joint and/or bilateral projects - The project has contributed to the master and PhD education, especially on IGBT reliability and converter control *Status for Publications and dissemination of results (by June) - 21 conference papers and 4 journal papers - About 50 Technical Reports/Project Memos submitted to the project eRoom The most comprehensive research tasks have been on IGBT reliability and on converter control, where also the most significant results have been gained. Especially mentioned is the valuable contribution from TU Chemnitz on IGBT reliability, including the accomplishment the PhD scholarship of Tilo Poller, the researcher exchange (also supported by two DAAD projects), and the production and commissioning of the of the Power Cycling Tester for life-time testing of high-power IGBTs. On converter control is especially mentioned the main focus on control methods for conventional grid connected converters, where substantial work was accomplished by the PostDoc work of Salvatore D'Arco leading to further work on a new and more robust control algorithms. SINTEF is prepared to utilize the achieved competence and experience from the project by contributing to further advances on reliable and energy efficient power electronics for the renewable energy sectors, as well as for other sectors involving power systems including complex and demanding power electronics conversion systems: - By continuing generic research - e.g. on reliability. - As bilateral projects with the project partners - By 3rd part verification and qualification of converter system topologies, control systems etc.

Successful realization of high power renewable energy projects like offshore wind parks bring about quite a few new challenges regarding power electronics. The project applicant believes that two of the most important challenges that need to be met will b e energy efficient conversion of energy from high cost production units, and to substantiate sufficient reliability and availability of conversion units. Efficient and reliable conversion will be the two most important sub-goals for the project. On compon ent fault mechanisms involving semiconductor devices the Chemnitz University of Technology will be a valuable partner. Other sub-goals are advanced control strategies for grid-connected converters, wide-band models for various power components, and real-t ime emulators for power components. The ambition for the applied project is to give a significant contribution to the already significant international R&D work on within these areas. It is also the ambition to provide the project partners with decision b ases and software tools for developing new applications of power electronics. Also new concepts for power grids will be made possible by power electronic conversion and control. The project goals will be approached by accomplishing realistic scenario anal ysis of renewable energy system grids, supported by numerical simulations and energy laboratory experiments. As an integrated part of the project the SINTEF staffs involved is also planned for guidance of MSc and PhD students at NTNU, thereby giving a sub stantial contribution of new expertise to the industry. The project plan includes financing of one PhD scholarship and one Post doc.