Energy storage sizing for effective primary and secondary control of low-inertia microgrids

Microgrids are poised to become a major worldwide development in light of the numerous benefits they offer. However, the control and management of such systems require keen attention, as stability issues in microgrids have proven to be an important topic of research. It is a point of emphasis, that microgrids operating as stand-alone systems are particularly unforgiving in the sense that the combined inertia of local synchronous generators may not be significant enough to ensure good stability margins. Therefore, energy storage may be prescribed as a mitigation option for achieving frequency and voltage stability in low-inertia systems. This paper considers the electrical frequency dynamics of low-inertia microgrids as well as the voltage regulation implications of associated power electronic interfaces. A design criterion for sizing energy storage systems (ESS) is provided to ensure that frequency and voltage stability margins are not violated in face of an electrical disturbance.