Souhir Sallem

Three-phase self-excited induction generator analysis in stand-alone mode

Currently, to supply power for a modern life, many researchs are being directed at alternative energy sources. One of the most promising sources is wind energy. In isolated systems, squirrel cage induction generators with capacitor excitation, known as self-excited induction generators (SEIG), are very popular. This paper presents a steady state analysis of three-phase self-excited induction generator with parallel compensation. An arrangement using a variable speed drive and a 4.4 KW induction machine excited with a capacitor bank to supply resistive or resistive-inductive loads was the subject of investigation. A new method, for determining the minimum and maximum capacities ensuring the performance of self-excited induction generator by a simple mathematical model, is presented.

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.

An improved Backstepping technique using sliding mode control for transient stability enhancement and voltage regulation of SMIB power system

Abstract The problem of transient stability and voltage regulation for a single machine infinite bus (SMIB) system is addressed in this paper. An improved Backstepping design method for transient stability enhancement and voltage regulation of power systems is discussed beginning with the classical Backstepping to designing the nonlinear excitation control of synchronous generator. Then a more refined version of this technique will be suggested incorporating the sliding mode control to enhance voltage regulation and transient stability. The proposed method is based on a standard third-order model of a synchronous generator connected to the grid (SMIB system). It is basically implemented on the excitation side of the synchronous generator and compared to the classical Backstepping controller as well as the conventional controllers which are the automatic voltage regulator and the power system stabiliser. Simulation results prove the effectiveness of the proposed method which ameliorates to a great extent the transient stability compared to the other methods.

Optimal tuning of power system stabilizer using genetic algorithm to improve power system stability

In the few past decades, power system stabilizers play an important role in power systems by ensuring the stability of the single machine infinite bus power system. In this context, several researchers have devoted their work to design the structure of the PSS and to optimize its parameters. In this paper, the structure of the integrated PSS is described. In order to optimize the PSS parameters, the genetic algorithm approach is proposed, developed and used. The performance of the proposed optimization method was evaluated by applying a short circuit default on a single machine infinite bus power system. Different results demonstrated that the genetic algorithm is able to find the optimal parameters of the PSS ensuring the stability of the power system.

A comparative study of PI and Sliding mode controllers for autonomous wind energy conversion system based on DFIG

Nowadays, the electricity demand in remote areas is increasing. Among a variety kinds of renewable energy sources, wind energy is very used. This type of energy presents a realistic alternative for power production. Therefore, to ensure optimal use of this energy, different control strategies are well studied in the literature. In this work, an autonomous wind energy conversion system based on a double fed induction generator (DFIG) is studied and modeled. The main goal of this work is to maintain the stator voltage and frequency to their reference values (220V, 50Hz) under variable mechanical speed and load variations. To achieve this purpose, two types of controllers are studied and compared: The vector control (PI) and the sliding mode controllers. Simulation results demonstrate the high precision and the robustness of the sliding mode controller compared with the vector controller (PI) mainly in case of wind speed variations and load demand changes.