Omar Naifar

Improving grid connected hybrid generation system supervision with sensorless control

In this paper, speed identification and control problems are simultaneously considered for a micro-grid power generation system (MG-PGS). To eliminate mechanical sensors, an observer has been designed to identify the speed of a wind energy conversion system based on a permanent magnet synchronous machine (PMSM). The proposed observer is an adaptive interconnected structure with online parametric estimation. Moreover, a new control based on the Lyapunov theory has been developed in order to improve sensorless control of a flywheel energy storage system based on induction machine. In fact, the main idea of this control technique is based on an appropriate choice of voltage control values that guaranty the global stability of the controlled system. Simulation results indicate that the sensorless control applied to the MG-PGS improves performances of the global control. The PMSM mechanical speed, the stator resistance, and inductance could be estimated precisely, and the dynamical property of the system is ob...

A vector control of a cascaded doubly fed induction generator for a wind energy conversion system

This paper presents a study developed about variable speed wind turbine system based on doubly fed twin stator induction machine (DFTSIG). In this paper we discuss the different architectures of the cascaded DFTSIG, in the case of direct coupling and indirect coupling. The wind generators modeling and control are presented; we have chosen a model with direct oriented vector control to ordering the power exchange between the machine stator controlled via a bidirectional converter. This control is developed and tested by synthesizing proportional integrator regulator.

Practical stability for a class of nonlinear time varying systems including delayed perturbation

In this paper we deal with the stability analysis problem of a class of nonautonomous delayed nonlinear systems. Using a Lyapunov-Krasovskii functional, some stability conditions are formulated and the practical stability of the proposed system is proved. Finally, illustrative examples with simulation results are given to demonstrate the validity of the result.

FTS and FTB of Conformable Fractional Order Linear Systems

In this paper, an extension of some existing results related to finite-time stability (FTS) and finite-time boundedness (FTB) into the conformable fractional derivative is presented. Illustrative example is presented at the end of the paper to show the effectiveness of the proposed result.

Discussion on Barbalat Lemma extensions for conformable fractional integrals

ABSTRACT In this paper, the Barbalat-type lemmas for conformable fractional order integrals which can be used to conclude the convergence of a function to zero is discussed.

Sliding mode control for induction machine based on the Lyapunov theory

In this paper, we develop a new control approach for IM. The IM mechanical speed variable perfectly follows its references through a PI controller based on the sliding mode. The associate PI gains of the flux regulator are calculated by pole placement method. The basic idea of this technic is to make stable the closed loop system in the sense of Lyapunov. This method compared with traditional IM control use a simple calculation by the fact that we obtain a global asymptotic stability. The objective of this control technic is based on an appropriate choice of the voltage control values that guaranty a global stability of the closed loop system.

Observation of IM mechanical speed Comparative study of a high gain interconnected observer and an adaptive observer

In the context of a more detailed knowledge of nonlinear observers, we become interested in studying the behavior of the speed error of the induction machines for various function regimes. The aim of this work is the comparison between two types of observers applied to the induction machine to allow the proper selection of the solution. The observers selected are the adaptive observer and the interconnected observer.

A new control technic for induction machine based on the Lyapunov theory

In this paper, we develop a new control approach for IM. The basic idea of this technic is to make stable the closed loop system in the sense of Lyapunov. This method compared with traditional IM control use a simple calculation by the fact that we obtain a global asymptotic stability. The objective of this control technic is based on an appropriate choice of the voltage control values that guaranty a global stability of the closed loop system. The IM mechanical variables perfectly follow their references through two PI controllers. The associate PI gains are calculated by pole placement method.