This work was supported in part by the Faculty of Engineering and Information Technologies, The University of Sydney, under the Faculty Research Cluster Program, in part by National Natural Science Foundation of China under Grant 61233008, Grant 51277014, Grant 51207014, and Grant 71371065, in part by the Scientific Research Fund of Hunan Provincial Education Department (No. 15B006), in part by the Natural Science Foundation of Hunan Province (No. 2015JJ4001), and in part by Hubei Provincial Collaborative Innovation Center for New Energy Microgrid, Hunan Provincial Collaborative Innovation Center for Clean Energy Generation and Electric Power Technology. Paper no. TPWRD-01425-2015.R2.