Robust voltage controller design for an isolated Microgrid using Kharitonov’s theorem and D-stability concept

This paper proposes a new robust voltage control strategy for an isolated Microgrid (MG). The MG consists of several Distributed Generation (DG) units and local loads, which should be capable to operate in both connected and disconnected modes. To achieve this goal and suitable performance in both modes, robust control may provide many advantages. The proposed control structure proceeds to design a robust voltage controller based on Kharitonov’s theorem for an isolated MG system. It utilizes an internal oscillator to frequency control and a proportional–integral (PI) controller to maintain voltage stability that is tuned by Kharitonov’s theorem. For fine-tuning of the PI controller, D-stability concept as a complementary method is used. The PI voltage controller endeavors to minimize errors between direct and quadrature voltage components and their reference values. Performance of the robust voltage control method and isolated MG system are evaluated by several simulations in the presence of uncertainty in the system parameters.

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► Microgrid (MG) concept in the modern power systems is an aggregation of loads and small sources.
► The MGs are usually working in connected mode but it is possible to go in islanded operating mode.
► Robust control is an essential need to stability preserving in the isolated MG systems.
► This paper proceeds to design a PI voltage controller for an isolated MG system.
► The controller is robustly tuned based on Kharitonov’s theorem and D-stability approach.