Smart hybrid energy management system for green microgrid with optimized energy and enhanced voltage stability

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.