Power sharing scheme for an islanded microgrid including renewables and battery storage

Microgrids provide an effective way to increase renewable energy (RE) penetration level in the power network. The cooperation of renewable microsources, energy storage systems (ESSs) and conventional dispatchable microsources is an important issue in the operation of an islanded microgrid. In this paper, the designed power sharing scheme aims to maximize renewable penetration level by giving RE the priority of power supply. This requires RE to be able to regulate grid voltage rather than only operating under power control mode (PCM) in the conventional way. Droop control strategy is modified to support a microsource operating under both voltage control mode (VCM) and PCM, and switching between both modes automatically. It also enables 'peer to peer' and 'plug and play' operation of a microgrid. Meanwhile, the characteristics of power sources (photovoltaic and batteries) are considered. DC/DC converter controller is proposed correspondingly with the aim of keeping the system stable. Simulations have been conducted to verify its effectiveness.