Abstract:
Energy management systems (EMSs) are an integral part of power networks with distributed energy resources (DERs) for optimized energy transactions. Conventional EMS performs rule-based actions for energy transactions between the DERs without considering optimization of resource and network stability. This paper proposes a smart hybrid EMS for an AC microgrid with optimal energy transactions with the utility distribution grid for improved cost-benefits along with stabilizing the voltage levels at the point of common coupling (PCC) using VAr compensation. The proposed EMS incorporates a hybrid scheme of rule based prioritization combined with an optimization module for energy management based on forecasted data of AC microgrid under grid-connected and islanded conditions. This reduces the operational cost of energy by at least 20% compared to classical EMS through a systematic cost-benefit analysis of microgrid. Besides, it aims at reduction of carbon emissions by at least 30% compared to classical EMS by prioritizing renewable energy sources and optimizing energy transfers. The proposed EMS not only ensures the active power management of a photovoltaic (PV) source, a battery energy storage system (BESS) and a diesel generator under different operating conditions but also performs VAr compensation using the grid-tied converters of PV and BESS which are dynamically limited by the EMS depending on the rated VA of the respective entities and the real-time active power injected. The simulation results from MATLAB/SIMULINK, analysis along with validation using the laboratory grid-tied converter prototype with PV source and battery setups establish the effectiveness of the proposed smart EMS.