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In this paper we address the problem of voltage restoration and control of inverter-based islanded microgrid. The problem is attacked from a multi-agent systems consensus-based perspective at the microgrid’s secondary control layer. An ad-hoc chattering-free second-order sliding-mode controlled is designed to achieve voltage restoration in a distributed way while enhancing the underlying system’s robustness. With respect to existing solutions, the proposal do not require neither the knowledge of any grid parameter nor model-based information on the distributed generators. Performance of the proposed control system is analyzed by Lyapunov tools, and a simple set of tuning rules, guaranteeing the achievement of exact finite-time voltage restoration, are obtained. Computer simulations support the effectiveness of the strategy.

This paper outlines some results concerning the application of second-order sliding-mode techniques to address estimation and fault detection problems involving fractional order (FO) dynamics. Perturbed and switched FO systems are dealt with throughout the paper. Simple tuning formulas for the suggested schemes are constructively developed along the paper by means of appropriate Lyapunov analysis. Simulation and experimental results confirm the expected performance.

This paper addresses a problem of state and disturbance estimation for an open channel hydraulic system. More precisely, a cascade of ncanal reaches, joined by gates, is considered, and, by using measurements of the water level in three points per reach, we design an observer capable of estimating both the infiltration and discharge in the middle point of each reach. To facilitate the observer design, the system dynamics is modeled by considering a linearized approximation of the underlying nonlinear dynamics around the subcritical uniform flow condition. The proposed solution is based on the unknown-input and proportional-integral observers theory. Simulation results are discussed to verify the effectiveness of the proposed schemes.

In the present paper, preliminary results towards the generalization to the infinite-dimensional setting of some finite-dimensional second-order sliding mode control algorithms are illustrated. The main focus of the present paper is on the rejection of non-vanishingexternal disturbances. The “Twisting” and “SuperTwisting” second-order sliding-mode control algorithms (see (Levant (1993))) are properly generalized to address the state tracking problem for the wave and heat equations. Constructive proofs of stability are developed via Lyapunov functional technique, which leads to simple tuning rules for the controller parameters. Simulation results are discussed to verify the effectiveness of the proposed schemes.

This paper deals with the motion control problem for an underwater vehicle (UV) prototype built at the University of Cagliari. The vehicle is equipped with a special propulsion system based on hydro-jets with variable-section nozzles. To cope with the heavy uncertainties affecting the prototype dynamics, the control system has been developed by means of the second-order sliding-mode control (2-SMC) approach. Chattering is removed since the 2-SMC approach confines the high-frequency switching to the higher derivatives of the control variable. The UV velocity is estimated in real-time by means of a recently-proposed variable-structure robust differentiator, and the experimental results show that a fast and accurate response can be obtained under several operating conditions. The control system and the main implementation issues are discussed in some detail.