Decentralized Voltage and Frequency Control in an Autonomous ac Microgrid using Gain Scheduling Tuning Approach

The renewable energy resources provide us with green energy and flexible integration into power grids, but due to their variable nature, they cause significant frequency, voltage and power fluctuation for power system so that a sophisticated control strategy is needed to cope with these challenges. In this paper, the proposed control strategy consists of inner voltage and current controller and outer power loop. In this study, at first, coefficients of conventional PI controllers are obtained by a proposed objective function, and then it is shown that this PI controller with constant parameters doesn’t work properly over wide range of load variation, and the system is likely to be unstable. To obtain better performance, gain scheduling tuning approach is proposed to adjust PI coefficients for resistive, inductive and capacitive loads. This approach is applied to an autonomous three bus ac microgrid using Particle Swarm Optimization