Operation strategies of hybrid energy storages in low-voltage distribution grids with a high degree of decentralized generation

With the assumption that photovoltaic sysetms will use all available roof areas in the future, it is not possible to integrate the entire PV potential in today's low-voltage distribution grids. Due to the enormous feed-in of fluctuating electrical power in low-voltage grids by small-scale photovoltaic plants, transformers and cables can reach their loading limits. Moreover, the grid voltage can exceed permissible thresholds. In this paper the maximum feed-in that low-voltage energy distribution networks can be supplied with is being evaluated. The results show that it is not possible at present to integrate the entire potential of photovoltaic power plants in the distribution grids. Local energy storages, which save the surplus generation, can be an alternative to grid reinforcement and can be essential for a stable and efficient energy network in the future. Optimization methods using forecasts can lead to a more efficient usage of energy storage systems and enhance the self-consumption of the local energy generation. The combination of at least two different storage technologies, so-called hybrid storage systems, provides a solution to combine the advantages and simultaneously minimizes the aging of the energy storage system.