Secondary droop for frequency and voltage restoration in microgrids

Droop based autonomous control offers several advantages such as communication independence, plug-n-play capability and enhanced reliability of the system. Despite these advantages, frequency and voltage of droop controlled microgrid varies with the load change which is one of the major drawback of the droop control. Presently, the frequency and voltage restoration in microgrid is achieved through secondary control using low bandwidth communication links. This paper presents secondary-droop based frequency and voltage restoration method which is fully autonomous and independent of communication links. With the proposed method, the microgrid frequency and voltage can be restored back to nominal value without affecting the power sharing performance of the generation sources. The proposed scheme performance has been validated in simulation for several cases of active and reactive power load conditions.