Wind Energy Conversion Systems as Active Filters: Steady-State and Transient Analysis

Wind is one of the most popular and promising renewable energy sources. In the last years, technological advances have resulted in wind power plants that are more reliable, efficient and compatible with the existing grid. Moreover, recent research developments show that Wind Energy Conversion Systems (WECSs) can provide ancillary services in addition to power generation. In particular, the WECS can be used as an Active Filter (AF) to sink the harmonic currents injected by NLLs connected to the same feeder.
This presentation details the steady-state and transient operation of a Wind Energy Conversion System (WECS) operating as power generator and AF simultaneously.
The main research contributions are as follows:
1) The definition of three new and alternative control systems that allow the described operation of the WECS.
2) The inclusion of compensation of triplen (zero-sequence) harmonics.
3) The calculation of power loss increase caused by harmonic currents injection; derating of the WECS components is necessary to reduce the power loss when it exceeds the rated value.
4) The estimation of voltage distortion due to harmonic current flow.
5) The comparison of the three control methods in terms of power loss, derating and voltage distortion.
6) The investigation of the control system response to voltage variations and wind speed variations.
Simulation results prove that the WECS can be effectively used as AF; an engineering economic study indicates under which conditions operating a WECS as described above is more convenient than the installation of a dedicated AF.
Grazia Todeschini earned her B.S. and M.S. in Electrical Engineering from the Polytechnic of Milan, Italy, in 2003 and 2005 respectively and her Ph.D. in Electrical and Computer Engineering from Worcester Polytechnic Institute, MA, in February 2010. Her research interests deal with Renewable Energies, Power Systems, Power Electronics and Control. In November 2009 she was awarded a Student Grant from the Power Sources Manufacturers Association (PSMA) for participating at the Applied Power Electronics Conference, APEC 2010, where she presented part of her doctorate research. She has been member of the working group on IEEE Standard 1459-2000 (2010 revision and reaffirmation).