1. Engineering Laboratory of Power Equipment Reliability in Complicated Coastal Environments, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
2. Institute of Materials, China Academy of Engineering Physics, Mianyang 621907, China
3. State Grid Jiangxi Electric Power Research Institute, Nanchang 330096, China
4. School of Electrical Engineering, Chongqing University, Chongqing 400044, China
5. State Key Laboratory of Power System Operation and Control, Tsinghua University, Beijing 100084, China