1. Digital Grid Research Institute of China Southern Power Grid Guangzhou 510663 China
2. Power Generation Company China Southern Power Grid Co. Ltd. Guangzhou 510630 China
3. Guangdong Key Laboratory of Clean Energy Technology South China University of Technology Guangzhou 510640 China
4. Department of Electrical Engineering School of Automation Guangdong University of Technology Guangzhou 510006 China
5. Department of Electronic and Electrical Engineering University of Sheffield Sheffield S1 3JD UK