Decentralized Master-Slave Control for Series-Cascaded Islanded AC Microgrid

Series-cascaded microgrids (MGs) are gaining increasing popularity because of their control flexibility and ability to synthesize high voltage levels from low power rated modules. Several control schemes have been reported for autonomous power sharing in series-cascaded MGs that incorporate dispatchable distributed generators (DGs) only. In contrast, this article develops a series-cascaded MG formed by dispatchable and nondispatchable DGs. Achieving power balance as well as voltage and frequency regulation in this MG configuration is a challenging task. In this article, we propose a decentralized master-slave control scheme that regulates voltage and frequency and maintains power balance. The proposed scheme ensures the maximum utilization of nondispatchables, incorporates autonomous power curtailment under light-load conditions, and offers system reliability comparable with the traditional parallel structure. The proposed MG configuration and control scheme are thoroughly validated via simulations and experiments under various operating scenarios.