CONSENSUS CONTROL FOR POWER SHARING IN AN ISLANDED MICROGRID USING AN ADAPTIVE VIRTUAL IMPEDANCE APPROACH
Saudi Digital Library
Power sharing among distributed generators (DG units) in islanded microgrid (MG) applications presents control challenges particularly under the condition of mismatched feeder lines. These challenges aggravate in the event of unbalanced and nonlinear loads which often induce poor reactive, apparent imbalanced, and harmonic power sharing. This dissertation details a mathematical model of an adaptive virtual impedance compensation approach based on a leaderless consensus control algorithm with a novel triangle mesh communication topology to ensure correct active, reactive, apparent imbalanced, and harmonic power sharing. The secondary leaderless consensus control adapts the virtual impedance loops in the primary control in order to ensure an effective equivalent impedance of the feeder lines. The contribution of this proposed control methodology is to extend the recent works to control the event where the DG system supplies power to different types of loads, balanced, unbalanced, and nonlinear, and ensure efficient power sharing among DG units with the same or different power ratings. A MATLAB/Simulink model with six DG units validates the proposed control performance under various situations. The simulation findings demonstrate that the proposed control gradually eliminated the variations in the output currents, positive and negative current sequences, and each harmonic current to share the reactive, apparent imbalanced, harmonic power accurately based on their power ratings. The triangle mesh communication topology provides an enhancement on the rate of convergence for all powers and prevents reliance on the leader of the DG unit agent. In addition, the simulation findings indicate that the proposed control retains a stable condition in the event of a delay in the communication links as long as the time delay is less than the maximum time delay.