Energy management system for optimal cost and storage utilization of renewable hybrid energy microgrid

• Improved energy management system was proposed for hybrid solar and wind energy microgrid with battery storage. • The improvement was based on a contribution factor to operate the battery storage and load shifting mechanism. • Different functions were applied for the contribution factor based on the grid tariffs. • The proposed EMS was assessed based on the energy cost and the battery degradation. • The proposed method provides better performance compared to conventional energy management system. This paper proposes an improved energy management system to reduce the energy cost and the storage utilization of a hybrid solar and wind energy microgrid with battery storage and grid-connected option. The performance improvement relies on a parameter, called the contribution factor, that provides an adequate amount of the required power from the battery based on the electricity price of the main grid. Different profiles, for that factor, are investigated to enhance the system performance. Load shifting mechanism has been integrated into the energy management to enhance the energy cost. The system uses the efficiencies of the components to accurately compute the energy cost. Simulations have been performed for different rates of the load demand and results have shown the superiority of the proposed energy management system compared to the conventional one with respect to reducing the energy cost, the battery degradation cost and increasing the battery lifespan. From the results, it has been found that using a linear profile for the contribution factor and the load shifting will result in daily costs of $68.27 and $0.81 for the energy and the degradation, respectively. These costs represent a 25.66 % decrease in energy cost and a 91.72 % decrease in battery degradation cost compared to the conventional energy management system where the grid electricity and the load shifting are not considered in the usage of the battery storage.