1. School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China
2. Key Laboratory of Power Electronics for Energy Conservation and Drive Control of Hebei Province, Yanshan University, Qinhuangdao 066004, China
3. Department of Electric Power Station and Automation of Power Systems, The Institute of Energy, Peter the Great Saint-Petersburg Polytechnic University, 195251 Saint Petersburg, Russia