Hybrid Electric Energy Storage Module for Distributed Energy Storage Systems Based on Ecologically Acceptable Supercapacitor

This paper deals with an electric energy storage system (ESS) of distributed structure composed from the hybrid energy storage modules (HESM). Each module consists of the lead acid battery and the supercapacitor (SC) pack, which are connected to each other by the bidirectional DC-DC converter. The uniqueness of the proposed structure is that the DC-bus of whole ESS is formed by means of adding the SC pack voltages of all modules. For low voltage modules, it is proposed to use an ecologically acceptable SC with aqueous solution of KOH. Such SC has a low production cost, but also low voltage, no more than 1.2 V. For increasing specific characteristics of the SC with nonorganic electrolyte, the technology of its production was developed. This technology includes the next stages: receiving the biocarbon material from flax fibers with a developed specific surface area, carbonization and activation of the flax biocarbon at optimum regimes, its doping with iron, folding the electrodes, filling them with electrolyte, and sealing the cells. A control system was developed for the created HESM. The proposed HESM is built by Matlab/Simulink to verify its feasibility. Finally, a prototype of HESM is also set up to test the performance.