Search

The application of microgrids (MG) has a vital role in grid modernization. However, a larger number of installations of electronically coupled distributed energy resources (DER) units in MGs have created opportunities and threats for grid operations. Therefore, efficient and reliable control strategies for MG operation are essential. This article introduces the concept of sector design to show the stabilization of voltage source converter-interfaced DER units in MG applications. The sliding sector design is advanced sliding mode control to obtain a region of attraction such that the state space is divided into attractive and nonattractive regions. In addition, a variable structure-based controlling method has been introduced to drive the trajectories of a plant from the exterior to the interior of the sector and strictly inside throughout the process. In autonomous MG operation, the proposed controller focuses on stabilizing the electronically coupled DER unit's voltage and frequency response. Besides, it confirms the safety of the power conversion system from external disturbances. The system stability is proven using the Lyapunov candidate function. The proposed strategy has been effectively validated through PSCAD/EMTDC. The simulation results have examined the impact of balanced, unbalanced, nonlinear, and dynamic loading patterns in islanded MG. [ABSTRACT FROM AUTHOR]

In this article, an implicit Euler algorithm for digital implementation of constrained stabilization is studied for the second‐order systems. For that, a switching controller is designed in a discrete‐time framework such that the system's position output converges to some predefined range, that is, ϱ ∈ (−ε, ε) in finite‐time while the velocity output converges to the origin, that is, ϱ˙=0, in finite‐time. The switching controller is switched to the implicit Euler implementation of twisting algorithm when ϱ ∉ (−ε, ε) and to an implicit Euler implementation of first‐order sliding mode control when ϱ ∈ (−ε, ε). The combination of the two implicit Euler implementations achieves discrete‐time constrained stabilization of second‐order systems, avoiding the chattering caused by conventional explicit integration schemes. The usefulness of the proposed algorithm for constrained stabilization is illustrated by considering the container‐slosh coupled dynamical system. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of traditional sliding mode control design subject to the mismatched disturbance. Existing methods fail to provide an efficient and simple solution. To counteract the unmatched disturbance in the system, a new sliding mode control strategy based on a non-smooth integral sliding manifold is proposed. The proposed sliding manifold has two important features. First, it acts like a reduced order disturbance observer since it estimates the mismatched disturbances by itself without any requirement of an additional observer design. Secondly, the system always starts from the sliding surface, hence, there is no reaching phase dynamics. Thus, the system trajectory is insensitive towards the disturbance from the initial point. The proposed method is tested on a coupled tank system to demonstrate its effectiveness. Both the simulation and experimental results are provided. • A non-smooth integral sliding manifold is proposed with modified sliding mode control design. • Act as reduced order disturbance observer to estimate mismatched disturbances without any additional observer design. • System trajectory is insensitive towards the disturbance as there is no reaching phase dynamics. • Proposed work is tested on a coupled tank system to demonstrate its effectiveness. [ABSTRACT FROM AUTHOR]

Abstract This paper studies the formation of multiple mobile agents with double integrator dynamics and their target tracking. An algorithm consisting of an observer and a feedback control law of the nonsmooth type is proposed for the purpose of achieving finite-time formation and target tracking. The development is based on the Multi-input Multi-output (MIMO) super-twisting like approach aiming at finite time convergence without chattering. In addition to the formation; tracking, chattering prevention and robustness is also provided by the sliding mode mechanism which is demonstrated by simulations. Highlights • Formation of multiple mobile agents and their target tracking is studied. • An observer based feedback control algorithm for finite-time tracking is proposed. • The design is based on the Multi-input Multi-output super twisting like approach. • Tracking and chattering prevention of the robust system are shown by simulations. [ABSTRACT FROM AUTHOR]