Battery-based storage systems in high voltage-DC bus microgrids. A real-time charging algorithm to improve the microgrid performance

摘要

Battery-based energy storage systems (BESS) play a crucial role on renewable energy sources-based microgrids (RES-based microgrids) since they are responsible for lightening the difference between generation and consumption. For this purpose, a BESS is usually the only one device in RES-based microgrids that has two functions: (1) to supply energy when there is energy deficit between renewable sources and load demand, and (2) to absorb energy when there is energy excess. Then, the BESS operation and therefore its lifetime is closely related to the energy management strategy (EMS). However, most solutions found in the scientific literature are based exclusively on power balance and battery state of charge (SOC) as main decision parameters; but by contrast, in case of BESS, it is critical a suitable charge control to ensure the maximum efficiency and minimum degradation, increasing BESS lifespan as much as possible, especially for those RES-based microgrids where the BESS is responsible for supporting the DC bus. This paper presents a new charging algorithm designed to prevent and mitigate the BESS degradation, assuring high charging efficiency when it is integrated into the microgrid and directly connected to high voltage-DC bus connection. Additionally, the proposed algorithm contemplates the possibility of taking advantage of all available renewable energy sources, assuming an increase in BESS performance. Simulation and experimental results will show that the proposed algorithm can improve the BESS and microgrid operation with respect to solutions proposed in the market and in the scientific literature.