A new approach for optimal sizing of battery energy storage system for primary frequency control of islanded Microgrid

• We used battery energy storage system for primary frequency control of Microgrid.
• Overloading power of battery energy storage system is used for frequency control.
• Permissible duration of overloading has a significant effect on frequency control.
• Overloading of BESS is able to support load-generation balance in short time.
• Optimal size of BESS mainly depends on the permissible duration of overloading.

This paper presents a method for determining optimal size of a battery energy storage system (BESS) for primary frequency control of a Microgrid. A Microgrid is assumed to be portion of a low voltage distribution feeder including sources such as microturbine, diesel generator, fuel cell and photovoltaic system with slow response for frequency control. A BESS due to its very fast dynamic response can play an important role in restoring balance between supply and demand. In this paper, overloading capacity of the BESS is employed for fast handling of the primary frequency control of a MG. To achieve this purpose, by considering overloading characteristics and limitations of the state of charge (SOC) of battery, a control scheme of dc/ac converter for the BESS is developed. Based on this scheme, overloading capacity of the BESS and its permissible duration for participating in primary frequency control is determined. Simulation studies are carried out using PSCAD/EMTDC software package to evaluate the performance of the proposed control scheme.