A Residual-Generator-Based Plug-and-Play Control Scheme Toward Enhancing Power Quality in AC Microgrids

In this article, an active power quality control scheme centered on an observer-based residual generator is proposed for power quality improvement in ac microgrids. The active power quality controller is realized by a plug-and-play (PnP) configuration and consists of three parts: the control of the power electronic converter, the flexible structure, and the optimization algorithm. By means of the observer-based realization of the Youla parameterization of a stabilizing controller, the active power quality controller with the PnP flexible structure is designed. The proposed active controller has the advantage of improving power quality without changing the structure or parameters of the original controller. The optimization of the controller is implemented by tuning the Youla parameterization system in the PnP flexible structure. Here, a gradient descent optimizing algorithm is applied to estimate the optimal tuning/control parameters online. Finally, extensive hardware-in-the-loop experiments and simulations are given to demonstrate the effectiveness of the proposed power quality controller.