Modeling, Control and Prototyping of a Highly Integrated Battery-Ultracapacitor System for Microgrids

A Highly-Integrated Battery-UltraCapacitor system (HIBUC) is presented in this paper. It consists of a battery pack and an ultracapacitor module, which are coupled to each other through a three-level neutral-point-clamped converter. The latter is connected to the point of common coupling between a microgrid and the main electric grid through a step-up transformer, which enables lower DC-link voltage rating and, thus, eases HIBUC prototyping without affecting its performances significantly. The DC-link is also connected to a dissipative voltage regulator, which has been designed with the dual purpose of preventing DC-link overvoltage and improving DC-link voltage regulation simultaneously. The effectiveness of the proposed configuration has been verified through a simulation study, which has been carried out in the Matlab-Simulink environment and refers to different HIBUC operating conditions.