1. Key Laboratory of Modern Power System Simulation and Control and Renewable Energy Technology (Ministry of Education), Changchun, China
2. College of Geo-Exploration Sciences and Technology, Jilin University, Changchun, China
3. College of Instrumentation and Electrical Engineering, Jilin University, Changchun, China
4. School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou, Guangdong, China