Robust Decomposition and Structured Control of an Islanded Multi-DG Microgrid

This paper presents a new robust control strategy for islanded operation of a microgrid consisting of several distributed generation (DG) units with arbitrary topology. Each DG unit is connected to its local load through a voltage-source converter, a series RL filter and a step-up transformer. The multi-DG microgrid with arbitrary connectivity graph is modeled as a linear time-invariant system subject to a parametric, norm-bounded uncertain block. By utilizing the developed model for multi-DG microgrids, a systematic approach for the design of structured dynamic output feedback control is proposed. A convex optimization problem is developed which yields a low-order dynamic controller of arbitrary structure such that the microgrid channels are all decoupled at the presence of load parameter uncertainties. Simulation case studies performed in MATLAB/SimPowerSystems Toolbox verify the performance of the proposed strategy.