Unified framework for frequency and voltage control of autonomous microgrids

A general and effective framework for the secondary control of islanded microgrids (MGs) including inverter-based distributed generators and conventional generator is proposed in this study. The proposed framework works based on fuzzy potential function method and provides a clear vision for system designer in order to set the cooperation of different distributed energy resources (DERs) in regulating MG variables. Different potential functions are defined for each controllable microsource such that the minimum value of the potential function represents the microsource control target. The set points of DER units are dynamically updated by the optimisation unit located in MG central controller using available communication links. In addition, the small signal stability assessment is used to determine the parameter of the fuzzy potential function to guarantee the system stability. The simulation studies are carried out in the time-domain, using the developed program in MATLAB environment. The results demonstrate the effectiveness and flexibility of the proposed framework in the frequency and voltage control of islanded MGs.