Chai Xueyan School of Electrical Engineering,Xi'an Jiaotong University,Shaanxi Key Laboratory of Smart Grid & the State Key Laboratory of Electrical Insulation and Power Equipment;Wang Hongbin Guangdong Power Grid Co., Ltd;Guangzhou power supply;Luan Le Guangzhou Power Supply Co., Ltd.;Zhou Kai Guangdong Power Grid Co., Ltd;Guangzhou power supply;Li Xue School of Electrical Engineering,Xi'an Jiaotong University,Shaanxi Key Laboratory of Smart Grid & the State Key Laboratory of Electrical Insulation and Power Equipment;Xie Minghui School of Electrical Engineering,Xi'an Jiaotong University,Shaanxi Key Laboratory of Smart Grid & the State Key Laboratory of Electrical Insulation and Power Equipment