Distributed secondary control of islanded microgrids using modified integral backstepping technique

This paper develops a nonlinear secondary voltage control scheme for a droop-controlled inverter-based islanded microgrid (MG). The proposed secondary voltage control is a distributed scheme that enjoys a simple communication network. The applied modified integral backstepping (MIB) controllers restore the voltage of each distribution generation (DG) to their reference values. An integral term is included in the conventional backstepping method to improve its dynamic performance in tracking a reference signal when voltage deviations and load disturbances exist. The control input law's design and the closed-loop system's stability are realized by the Lyapunov criterion in a step-by-step procedure. The proposed secondary voltage control's effectiveness for a prototype microgrid system is verified by simulating it on MATLAB and comparing the results with conventional backstepping and sliding mode control (SMC). A considerable improvement in the transient response of the MG system and computation time of the input generation is accomplished by applying the proposed MIB technique.