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This paper presents a new decentralized control strategy for the islanded operation of a microgrid under unknown load conditions. In the islanded mode of operation, the microgrid should provide the load with a set of regulated balanced three-phase voltages. The load which is parametrically and topologically uncertain can also be unbalanced and/or nonlinear. Thus, the use of conventional control strategies results in the poor performance and even instability of the microgrid system. The proposed method assumes that the load current is a measurable disturbance signal. The robust optimal controlapproaches are used to design a controller to overcome the disturbances resulting from the unknownloads dynamics. The optimization problem is converted to a convex problem and is solved using the linear matrix inequalities (LMIs). The performance of the designed controller is verified using time-domain simulations carried out in PSCAD/EMTDC software., QC 20160303

This paper presents an effective voltage control strategy for the autonomous operation of a medium voltage (MV) microgrid under nonlinear and unbalanced load conditions. The main objectives of this strategy are to effectively compensate the harmonic and negative-sequence currents of nonlinear and unbalanced loads using distributed generation (DG) units. The proposed control strategy consists of a multi-proportional resonant controller (MPRC) whose parameters are assigned with particle swarm optimization (PSO) algorithm. The optimization function is defined to minimize the tracking error at the specific harmonics considering the stability limitations. In this paper the performance of the proposed controller is investigated for a single DG unit. Due to the fact that DG units can be decentralized, this strategy generalizes for multi-DG unit networks. The performance of the proposed control scheme is verified by using digital time-domain simulation studies in the PSCAD/EMTDC software environment., QC 20160418