[1] Xi An Jiao Tong Univ, State Key Lab Elect Insulat & Power Equipment, Xian 710049, Peoples R China
[2] Univ Tennessee, Dept Elect Engn & Comp Sci, Knoxville, TN USA
[3] Northwest China Grid Co Ltd NWG, 50 Middle Segment East Huancheng Rd, Xian 710048, Shaanxi, Peoples R China