1. Xi’an Jiaotong University,School of Energy and Power Engineering,Xi’an,China
2. Xi’an Jiaotong University,School of Chemical Engineering and Technology,Xi’an,China
3. Shandong Electric Power Equipment Co. Ltd,Jinan,China
4. Xi’an Jiaotong University,State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an,China