End-to-End Efficiency Improvement Technique for Supercapacitor Energy Stores in Renewable Energy Applications

摘要

Traditional microgrid applications use of battery-supercapacitor hybrid converters as a common approach to mitigate the effects of fluctuations in renewable energy sources. With the hybrid supercapacitors having around 2.5 times higher energy density, in the future environmentally unfriendly batteries can be minimized or eliminated in micro grids. A battery receiving a charge of Q coulombs will store an energy content of QV joules, compared to a fully discharged capacitor bank receiving the same charge will store only QV/2 joules. Given this fundamental reason, if SC banks are only used for energy storage, an efficiency loss of up to 50% may be experienced. However, by inserting a useful resistive load within the charging loop of the capacitor bank this loss can be significantly minimized. This paper presents details of using this approach in a residential DC microgrid, where LED luminaires and inverter-driven white goods are connected to a solar powered DC bus.