Najib Essounbouli

New stable adaptive fuzzy approach to control uncertain nonlinear SISO systems

This paper deals with the synthesis of a new robust adaptive fuzzy control for a class of nonlinear and disturbed single-input single-output (SISO) systems. To attenuate the effect of both of the approximation errors and the external disturbances to a prescribed level, two signals are added to the indirect adaptive fuzzy control law: the first deduced from a fuzzy system allows approximation errors and external disturbances to eliminated; the second signal deduced from the Riccati equation attenuates the effect of the residual errors to a prescribed level. To illustrate the efficiency of the proposed approach, a simulation example is presented.

Robust smooth sliding type-2 interval fuzzy control for uncertain system

A new second order sliding modes type-2 fuzzy controller for nonlinear uncertain perturbed systems is developed in this paper. To overcome the constraint on the knowledge of the system model, local models related to some operating points were used to synthesize a type-2 nominal fuzzy global model. For sliding modes, two adaptive fuzzy type-2 systems have been introduced to generate the two super twisting signals to avoid both the chattering and the constraint on the knowledge of upper bounds disturbances and uncertainties. These adaptive fuzzy type-2 systems are adjusted on-line by two adaptation laws deduced from the stability analysis in Lyapunov sense. Many simulation results for a robot arm actuated by a DC motor are given to illustrate the good tracking performances and the smooth signal control obtained by the proposed approach.

Design and simulation of fuzzy controller and supervisor for a micro-hydro power plant

Micro-hydro power plants (MHPP) are usually built on mountains to provide electricity for rural areas. Most of MHPP are isolated from national electrical grid network, which requires a good control system to keep the MHPP frequency and voltage outputs constant in spite of changing user loads. This paper focuses on the development of a control system that consists of a fuzzy controller and a fuzzy supervisor. The fuzzy controller is used to ensure good frequency regulation and to limit the waste of the available water on the reservoir. The proposed fuzzy supervisor manages the electrical production between departures that form the mini-grid. It is able either to disconnect or connect the less preferred departures, according to the level of the available water. The proposed control system can be considered to be a mean of power quality control, to improve the frequency fluctuations caused by random power fluctuations on the load side. Simulation results show overall the effectiveness and feasibility of the proposed fuzzy control system.

DC-Bus Voltage Control Based on Power Flow Management Using Direct Sliding Mode Control for Standalone Photovoltaic Systems

Abstract Standalone PhotoVoltaic System (SPVS) performance is heavily dependent on the DC-bus voltage. A robust control of the DC-bus voltage results in a good stable-working system. This paper presents a new strategy, of controlling the different elements of the system, that helps to regulate the DC-bus voltage against abrupt load variation, and keeps the system working effectively even during the lack of batteries. It uses Sliding Mode Controllers (SMC) for DC-DC converters to improve the dynamic performance of the PV system. It protects the batteries by using them only when they are needed, and therefore extends the lifetime of the installation. The system is designed to supply both DC and AC loads in remote sites where no grid utility is available. It is composed of three photovoltaic arrays, a bank of batteries, a set of DC-DC and DC-AC converters, and DC/AC loads. The operations of the system are categorized into 04 modes, and their selection depends on the supply and demand of energy on one side, and the state of charge of the batteries on the other. The system is modeled and simulated in Simulink environment. Tests are done under very hard and quick variations of load, and results bear witness to the robustness of the controllers and to the high performance of the system as well.

Adaptive type-2 fuzzy second order sliding mode control for nonlinear uncertain chaotic system.

In this paper, a robust adaptive type-2 fuzzy higher order sliding mode controller is designed to stabilize the unstable periodic orbits of uncertain perturbed chaotic system with internal parameter uncertainties and external disturbances. In Higher Order Sliding Mode Control (HOSMC),the chattering phenomena of the control effort is reduced, by using Super Twisting algorithm. Adaptive interval type-2 fuzzy systems are proposed to approximate the unknown part of uncertain chaotic system and to generate the Super Twisting signals. Based on Lyapunov criterion, adaptation laws are derived and the closed loop system stability is guaranteed. An illustrative example is given to demonstrate the effectiveness of the proposed controller.

Adaptive fuzzy sliding mode control for MIMO nonlinear systems subject to actuator faults and external disturbances

A class of MIMO unknown nonlinear systems subject to uncertain actuator faults and external disturbances is studied in this paper using fuzzy approximation theory and sliding modes. Using the universal approximation theorem, an adaptive fuzzy control law is proposed to accommodate the uncertain actuator faults during operation. The considered faults are modeled as both loss of effectiveness and lock-in-place (stuck at some unknown place). Thanks to sliding mode technique, we proved that the proposed control scheme can guarantee that all signals of the closed-loop system to be semi-globally uniformly ultimately bounded and the convergence of the tracking error. A simulation example is presented to show the efficiency of the proposed approach.

Improvement of a photovoltaic pumping system for irrigation of greenhouses: Case study for Laghouat, Algeria

This paper aims to enhance the performance of a photovoltaic (PV) pumping system used for crop irrigation in greenhouses. Usually, most of the PV panels, which are used in such kind of systems, are sized and directly connected to the motopumps in a way that provide the maximum of its power. This configuration is simple, cheap, and efficient only under Standard Test Conditions (STC). In fact, environmental conditions are timevariables, and cause important power losses. In order to reduce the power losses and by consequence increasing the water flow, a dc-dc converter, controlled by a Maximum Power Point Tracking (MPPT) algorithm, has been inserted between the source and the charge. Simulation results proved a good performance of the system regarding to the gained solar energy and the daily pumped water.

Robust adaptive fuzzy tracking control for a class of nonlinear systems

This paper deals with the design of a robust adaptive fuzzy tracking control for a class of uncertain and disturbed nonlinear systems. In addition to the desired performances and the convergence of the tracking error, the proposed approach guarantees the uniformly ultimately boundedness of the resulting closed-loop system. Furthermore, it allows overcoming many problems related to adaptive fuzzy controllers like singularity problem and constraints on the control gain, and reducing the number of used parameters, which encourage the real-time implementation. Finally two simulation examples are presented to show the effectiveness and the performances of the proposed approach.

Forecasting of PWM-regulator dynamics

PWM energy converters (PEC) are rich in nonlinear dynamics. Thereupon in practical application increase of PEC efficiency is hold in the restrictions stipulated by nonlinear phenomena presence. A variant of this contradiction resolve seems to be in calling of the methods of PEC dynamics forecasting which allow applying of necessary control actions before abnormal process appearance. Fundamental problems of abnormal process forecasting are considered in the paper. Variants of problem solutions are analyzed within the bounds of the fractal method. Perspective ways of development are marked on the basis of this analysis results.