Performance of a smart microgrid with battery energy storage system's size and state of charge

A mini-grid with various distributed energy technologies such as micro-turbine, micro-hydro, wind, solar, and biomass is known as microgrid. A microgrid can either be connected to the main grid or operate stand-alone. Due to variable nature of renewable resources such wind and solar plants, energy storage becomes necessary to maintain reliability of power supply to critical loads if high level of wind and solar power penetration is to be maximized. Moreover, advanced energy management systems are critical to make intelligent decisions that minimize power outage to critical loads, and maximize the utilization of renewable sources of energy. The primary contribution of this paper is to investigate the impact of size and state of charge (SOC) of a battery energy storage system (BESS) for a given microgrid with dynamic energy management systems (DEMS). Results are presented to show the relative performance of two types of DEMS for a microgrid with different BESS size and initial SOC. The performance of an intelligent DEMS developed using an adaptive critic designs approach is compared with of a DEMS developed using a decision tree based approach.