1. Electrical Power Engineering and Mechatronics Department, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
2. Institute of Industrial Electronics and Electrical Engineering, Riga Technical University, 12/1 Azenes Street, LV-1048 Riga, Latvia
3. Department of Engineering Sciences, University of Agder, Postboks 422, 4604 Kristiansand, Norway
4. Department of Computer Science and Communications Technologies, Vilnius Gediminas Technical University, Saulėtekio al. 11, LT-10223 Vilnius, Lithuania