On the Robust Distributed Secondary Control of Islanded Inverter-Based Microgrids

In this chapter, some recent results of applications of sliding-mode control strategies for solving the AC microgrid secondary restoration control problem are discussed. The control problem is formulated in a distributed way in accordance with the leader–follower consensus paradigm thus avoiding centralized decision-making. The control schemes are robust in the sense that the voltage and frequency restoration of an inverter-based islanded microgrid is achieved under severe uncertainties affecting the grid and load dynamical models and parameters. In this chapter, two distributed sliding-mode-based control strategies are discussed. The first approach performs the task in finite time exploiting instantaneous communications among distributed generators, whereas the second one attains the goal with an exponential convergence rate by taking into account delayed communications among generators. Both the proposed strategies yield continuous control actions, with discontinuous time derivative, that can safely be pulse-width modulated by a fixed-frequency carrier, as required to not hurt the switching power artifacts. The performance of the proposed schemes is analyzed by means of Lyapunov tools and verified by means of numerical simulations taken in different operative scenarios.