ZHANG Ling1?覮,TIAN Ke2,ZHANG Wei1,SUN Yu-ming3
(1. Customer Service Center,State Grid Henan Electric Power Research Institute,Zhengzhou,Henan 450000,China; 2. Marketing Department of State Grid Henan Electric Power Company,Zhengzhou,Henan 450000,China; 3. Electric Power Research Institute,State Grid Henan Electric Power Company,Zhengzhou,Henan 450000,China)