1. North China Electric Power University,School of Electrical and Electronic Engineering,Beijing,China
2. China Southern Power Grid; National Energy Power Grid Technology R&D Centre,State Key Laboratory of HVDC, Electric Power Research Institute,Guangzhou,China
3. China Southern Power Grid; Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System,State Key Laboratory of HVDC, Electric Power Research Institute,Guangzhou,China