Maher Chaabene

Investigation on the Excitation Capacitor for a Wind Pumping Plant Using Induction Generator

This paper presents a SEIG-IM system using a self excited induction generator driven by wind turbine and supplying an induction motor which is coupled to a centrifugal pump. A method to describe the steady state performance based on nodal analysis is presented. Furthermore, a dynamic analysis and performance characteristics are examined. The pro-posed methodology is discussed in order to optimize the quantity of the pumped water. Therefore an optimal excitation capacitor for a given wind rotor speed is determined and a suitable operation mode of the system is established.

MPPT techniques for a photovoltaic pumping system

A study of some MPPT algorithms and type (central or distributed) for an off-grid photovoltaic installation is presented. First, the efficiency of using MPPT algorithms in a specific application (water pumping) has been proved. Then, some widely used MPPT algorithms (Table Look-up Neuro-fuzzy, Incremental Conductance and Perturb and Observe) are compared, independently on the application. Their performances are evaluated using measured data from the target area, and compared in similar conditions, thanks to simulations. Since the P&O algorithm is easy to implement, and it shows a fast dynamic performance, although the non-linearity of the photovoltaic panel model, it is selected to track the MPP and is successfully tested on a detailed model of a Buck converter, using PowerSim. Then, the power efficiency comparison between the central and distributed MPPT is discussed.

Fuzzy Energy Management for Photovoltaic Water Pumping System

A Fuzzy energy management algorithm for a photovoltaic water pumping installation is presented and validated experimentally, using a plant composed of photovoltaic panels, battery banks, DC/AC converters, relays and a water pump. Considering many criteria related to the battery safe operation, fulfilling the water volume needed by the crops and ensuring a continuous function of the pump, the algorithm decides the switching of the relays, which link the installation’ components. The algorithm is evaluated for a specific case study: tomato irrigation in Tunisia. Obtained results confirm that the irrigation water demand is covered during the season with a minimum use of the battery. General Terms Fuzzy logic, Photovoltaic Energy management.

Characterization tool for photovoltaic power sources

This paper presents a software that simulates and characterizes photovoltaic systems (PV). The tool reveals the effect of the climatic parameters and the state of the load on the behavior of the photovoltaic conversion system. Different approaches are programmed to track the maximum power point such as fuzzy logic, P&O, etc… Furthermore, several functionalities are supplied as diagrams of the electric characteristics (current, voltage, power). Simulation is executed using PV parameters according to either a set of PV known companies or by programming specific PV configuration. Validation is ensured thanks to a stored measurement database relative to Sfax, Tunisia. Thanks to an interactive graphic interface, the software offers a great flexibility when teaching, characterizing, modeling or sizing photovoltaic installations.

Energy scheduling strategy for a photovoltaic/batteries bank/diesel generator power supply system for an off-grid house

A novel algorithm is proposed to control the overall energy produced by a photovoltaic/battery bank/diesel generator renewable energy system. A renewable energy system is used to supply an off-grid connected house in Sfax, Tunisia. The algorithm computes recurrently the battery depth of discharge and diesel consumption of the diesel generator and then forecasts the photovoltaic subsystem output power every two minutes ahead. The estimated power is computed using an auto-regressive moving average model associated with a Kalman filter. During each calculation loop, hybrid system energy scheduling is accomplished considering criteria that guarantee the maximum use of generated renewable energy, minimum diesel generator operational time, and full-load need satisfaction during the whole day. Numerical simulations for two typical sunny and cloudy days in Sfax, Tunisia, are conducted in order to validate the algorithm and to compare the performance of managed system behavior with that of a standard unmanaged sys...

Energy management for a photovoltaic-wind system with non-controlable load

In this paper, an energy management study of a photovoltaic-windsystem for a non-controllable load supply is presented. The control methodology decides on the switching between the installation components. The decision is made by an energy management algorithm that depends on the photovoltaic power, the wind turbine power, the battery bank state of charge and the load demand. The algorithm aims to ensure the system autonomy, a continuous load supply and a safe operation for the battery bank. For this, first, a TOR and a Fuzzy algorithm are explained and used to decide on the connection of the installation components. The obtained results shows the efficiency of Fuzzy logic in maximizing the use of the renewable energy and ensuring a safe operating for the battery bank.

A robust nonlinear of an Electric Vehicle in traction

This paper treats the traction control in Electric Vehicle driven by a Doubly Fed Induction Motor (DFIM). A robust nonlinear control law at the torque level is presented to cope with the unknown tyre reaction force. A parameter estimation function is computed for the adaptative control of the system with unknown friction forces. The consequent generated torque control law is implemented in the DFIM. A vector control technique of a DFIM is proposed. The approach is based on a flux orientation of the rotor with scalar control on the stator. The control strategy achieves the aim of traction control and maintains the slip ratio at constant value 0.2 when road surface varies.

Smart model for the identification of the induction motor parameters

This paper presents a numerical model which allows a fast identification of the induction machine parameters. The algorithm uses a parameter reduced model for which the identification of parameters is based on series of measurements of the steady-state current, voltage and speed. The model is validated while a starting test of the induction motor connected to three phase grid. The approach assessment confirms that the NMBE is less than 2.07%.

Wind potential assessment for an efficient wind farm sizing

The effectiveness of autonomous wind plants depends basically on the characterization, sizing, and environmental design and analysis of its renewable energy conversion system. This article presents an assessment on wind potential characterization to be used to compute the size of a wind farm turbine. Different methods are adopted to estimate parameters of the Weibull distribution. The modified maximum likelihood method is selected as the most accurate with reference to comparison between many approaches output results and measurements provided by the National Institute of Meteorology. Also, an artificial neural network–based algorithm is developed to optimize the MMLM parameters. The monthly wind potential distribution is consequently computed for Sfax, Tunisia. Obtained results are used to optimize the size calculation of wind turbine blades and battery capacity for a standalone wind farm. The proposed approach profitability is evaluated upon the lost produced energy.

Charcterisation of an off grid hybrid system: Modelling and simulation

In this paper, a modelling and simulation of an hybrid system composed of photovoltaic panels, a lead-acid battery bank and a diesel generator connected in parallel, is studied. A non-linear model that depends on the solar radiation and the ambient temperature is adopted to model the photovoltaic panels. The battery is characterized by the depth of discharge deduced by a non-linear model. The genset model consists in modelling its three parts: the diesel engine, the synchronous generator and the excitation system. The system characterization and simulation demonstrate that the load is supplied during the day even in case of weather disturbs.