1. State Key Laboratory for Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power UniversityBeijingPeople's Republic of China
2. Bradley Department of Electrical and Computer EngineeringVirginia Polytechnic Institute and State UniversityBlacksburgVirginia24061USA
3. Department of Substation DesignState Nuclear Electric Power Planning Design and Research InstituteBeijing100095People's Republic of China