Stochastic Distributed Secondary Control for AC Microgrids via Event-Triggered Communication

This paper proposes a stochastic distributed secondary control scheme for both frequency/voltage restoration and optimal active power sharing (e.g., minimize the total generation cost) of ac microgrids by employing event-triggered communication mechanism in noisy environments. Compared with existing ideal and periodic communication among distributed generations (DG), the proposed stochastic distributed secondary control scheme can achieve mean-square synchronization for frequency and voltage restoration of DGs and the optimal active power sharing for their economic operation through a sparse communication network, even though the communication channels are susceptible to noise interferences and limited bandwidth constraints. The stochastic distributed control protocols are designed to be employed into the secondary control stage for microgrids, which is a fully distributed control paradigm. With the proposed control protocols, control deviations of frequency and voltage produced during the primary control stage can be well remedied and the optimal active power sharing for their economic operation can be well achieved simultaneously. Furthermore, the graph theory, stochastic theory and Lyapunov functional approach are employed to derive the stability and convergence analysis of the proposed dynamic event-triggered conditions considering noise interferences. Simulation results on an islanded microgrid test system are presented to demonstrate the effectiveness of the proposed control protocols.