Robust Voltage Control in Inverter-Interfaced Microgrids Under Plug-and-Play Functionalities

In this article, a new scheme of designing decentralized extended proportional derivative (DEPD) controllers with combining novel disturbance observers is proposed for the issue of voltage control in islanded inverter-interfaced microgrids. A microgrid system under plug-and-play (PnP) functionality is described by an uncertain linear time-invariant system, and then, the stability of microgrid system is studied for voltage regulation based on the robust control theory and linear matrix inequality. The DEPD controller and the proposed disturbance observers are capable of minimizing undesirable oscillations in PnP operation of distributed generators and topology changes. To attenuate the effects of disturbances and uncertainties, a new nonlinear disturbance observer-based control strategy is provided in this article. The new disturbance observers proposed in this article can estimate any disturbances such as constant, harmonic, random walk, and any time-varying disturbances with slow varying rate. Some case studies and numerical simulations are investigated for evaluating the new control scheme via the MATLAB software. Simulations effectively validate the performance of the proposed approach.