1. Faculty of Energy, Novosibirsk State Technical University, 20 K. Marx Ave., 630073 Novosibirsk, Russia
2. Ural Power Engineering Institute, Ural Federal University, 19 Mira Str., 620002 Yekaterinburg, Russia
3. Faculty of Electrical and Environmental Engineering, Riga Technical University, 12/1 Azenes Str., 1048 Riga, Latvia