Browsing by Author "Djabali, Sarah"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Control and power quality improvement of three-phase PWM-Rectifier
    (2020) Djabali, Sarah; Ait Hamou Ali, Melissa; Ammar, Abdelkarim (Supervisor)
    This thesis presents performance enhancement of PWM-rectifiers. Several control strategies have been proposed for the PWM-rectifier, such as voltage-oriented control (VOC), direct power control (DPC) and their combination: DPC with space vector modulation (DPC-SVM). Moreover, various virtual flux estimation techniques have been presented as a sensorless control algorithm in order to rise system reliability by decreasing the number of sensors and improving line-voltage estimation accuracy. Finally, a recent control strategy based on model predictive control has been introduced; this strategy reduces the complexity of the control circuit. All presented techniques have been investigated through simulation using MATLAB/Simulink software. The simulation results validate the presented control strategies. Sensorless predictive control features excellent PWM-rectifier performance as well as high robustness to network distortions.
  • Thumbnail Image
    Item
    Enhanced sensorless predictive direct power control for PWM rectifier with constant switching frequency under grid disturbances
    (IEEE, 2021) Djabali, Sarah; Ammar, Abdelkarim; Kheldoun, Aissa
    This work presents a voltage sensorless predictive direct power control strategy for PWM-rectifier. Firstly, the line-voltages are estimated using Second-Order Generalized Integrators (SOGI) coupled with Frequency Locked Loop (FLL). SOGI are inherent noise rejectors and FLL provides instantaneous tracking of the grid frequency. Their combination offers high robustness against grid disturbances, distinctively: harmonics distortion and frequency fluctuations. Secondly, Model Predictive Control (MPC) with Finite Control Set (FCS) attributes conceptual simplicity and higher accuracy than conventional controllers but suffers from variable switching frequency. In this paper, we propose MPC approach that solves the switching frequency problem while maintaining the accu- racy of FCS. Last, the decoupled control between active and reactive powers of Direct Power Control (DPC) offers flexibility of operation over variable power factors. The effectiveness and reliability of the proposed approach are investigated through simulation using MATLAB/SIMULINK software
  • No Thumbnail Available
    Item
    Improved virtual Flux-Direct power control for PWM rectifier based on Second-Order generalized integrators
    (IEEE, 2020) Djabali, Sarah; Ait Hamou Ali, Melissa; Ammar, Abdelkarim
    The AC-DC conversion system in the power system use generally the diode-bridge based rectifiers that cannot be reversible and causes high current distortion. Besides, they reduce the power factor and energy quality. recently, the application of three-phase pulse width modulation (PWM) rectifier has been risen quickly due to breakthrough advancement in the power devices. This converter is widely used in many applications such as electrical drives and renewable energy conversion systems. It offers plenty of advantages, mainly sinusoidal input currents and minimized harmonic distortion and unity power factor. This work presents an improved sensorless control for performance enhancement purpose of the PWM-rectifier. The proposed control strategy uses the virtual flux principle with second-order generalized integrator (SOGI) in order to overcome the accompanying drawbacks of using pure integrator of low-pass filters for estimation. The integration of improved virtual flux estimator with direct power control saves the cost of using many voltage sensors which can increase the reliability and effectivity of the control system. The different proposed approaches have been investigated through simulation using MATLAB/Simulink software