Distributed Optimized Consensus-Based Frequency Synchronization in Isolated AC Microgrids

To achieve the autonomous frequency synchronization in isolated AC micro-grids (MG), a fully distributed optimal control framework with suppressing transient dynamics of each distributed generator (DG) is presented in this paper. The proposed distributed control scheme is proceeded by three steps. First, by exploring the input-output feedback linearization to a large-signal non-linear dynamical model of an isolated AC MG, each DG can be modelled as a decoupled linear system. Secondly, the linear system theory can be applied to each DG and the problem under study is re-formulated by a distributed optimization problem under DG dynamics and the frequency synchronization criterion. The objective function is defined as the sum of the integral of quadratic consensus errors and quadratic inputs. Finally, by exploiting the method of multipliers derived from the associated augmented Lagrangian, a fully distributed optimization algorithm can developed by integrating the alternating direction method of multipliers (ADMM) and the optimal control theory. To validate the performance of the proposed method, real-time simulations on OPAL-RT are conducted. Simulation results confirm that the proposed distributed optimized consensus-based control strategy can indeed improve optimal autonomous plug-and-play operations of the MG without large transient responses.