Distributed Secondary Control of Virtual Synchronous Generator Integrated Microgrid via Extremum Seeking

In this paper, an islanded microgrid with virtual synchronous generator integration is investigated and virtual synchronous generator dynamic model under dq reference is presented. Moreover, the distributed secondary controllers of microgrid are designed and allocated to each distributed generator by taking advantage of the simple structure of Extremum Seeking algorithm for purpose of adjusting the frequency of microgrid to its nominal value cooperatively during disturbance. The dynamic behavior of overall proposed two-layer system is analyzed. Regarding on frequency changing pattern, modifications is made on variable Extremum Seeking convergence gain and variable virtual synchronous generator inertia constant in order to achieve faster frequency restoration. Finally, simulation results regarding the frequency within microgrid physical network, active power allocation and control among distributed generators are given. Both theoretical analysis and simulation results reveal that the participation of distributed secondary controller recovers the frequency of microgrid to its nominal value quickly even though load disturbance occurs.