1. School of Electrical Engineering, Shenyang University of Technology, No. 111 West Shenliao Road, Shenyang, Liaoning, P. R. China
2. Institute of Economics and Technology of, State Grid Liaoning Electric Power Co., No. 183-1 Wencui Road, Shenhe District, Shenyang, Liaoning, P. R. China
3. Electricity Intensive Control Department of State Grid Liaoning Marketing Service Center, No. 19-A-1 East Hunnan Road, Hunnan District, Shenyang, Liaoning, P. R. China
4. Department of Energy Technology, Aalborg University, Pontoppidanstraede 111, 9220 Alborg, Denmark