9Huang A Q,Crow M L, Heydt G T, et aI. The future renewable electric energy delivery and management (FREEDM) system: The energy internetl[J]. Proceedings of the IEEE,2011,99(1) :133-148.
10Ibrahim H,11inea A,Perron J. Energy storage systemscharacteristics and comparisons[J]. Renewable and Sustainable Energy Reviews,2008,12(5):1 221-1 250.