Abdellatif Obbadi

Passive filter for harmonics mitigation in standalone PV system for non linear load

Several studies have been presented regarding the harmonics mitigation by using different types of filters. Passive filter is one of them and is employed due to his simplicity, economical cost and high reliability in power system. This paper presents an analysis and study of three types of passive filters to minimize harmonics distortion caused by non linear loads in standalone PV system. In order to achieve the certain filtering effect, it is necessary to combine different filter topologies; generally these topologies can be divided into two categories: series AC reactor and shunt passive filter such as tuned filters and high pass filters. This paper presents firstly the basic design and components of PV system, secondly describes the causes of harmonics and their effects and presents the means to improve power quality and to protect the equipment in our power system. The proposed system is verified by the simulation using Matlab/Simulink environment.

Design and sliding mode control for PMSG based wind power system connected to a non-ideal grid voltages

This study presents a control scheme of the electronic interface of a grid connected Variable Speed Wind Energy Generation System (VS-WEGS) based on a Permanent Magnet Synchronous Generator (PMSG). The proposed system consists of wind turbines (WT) and 2 PMSGs connected to the electric network by back-to-back Voltage Source Converter (VSC) with a common dc-link. The generator-side converters are employed to attain Maximum Power Point Tracking (MPPT). The grid-side regulator controls the reactive power flow, the voltage at the dc link between both sides and the power factor during wind variations. The reliability and effectiveness of wind energy is shown to be depending on the applied control strategy. So, the control schemes are based on Sliding Mode Control (SMC) for control of both generators and grid-side converters of a VS-WEGS. The performance of the system has been demonstrated under varying wind conditions and under a grid voltage dip. The proposed SMC strategy is compared with the conventional Vector Control (VC) method. The simulation results show a good performance of the proposed sliding mode control.

Power Extraction Control of Variable Speed Wind Turbine Systems Based on Direct Drive Synchronous Generator in All Operating Regimes

Due to the increased penetration of wind energy into the electrical power systems in recent years, the turbine controls are actively occupied in the research. This paper presents a nonlinear backstepping strategy to control the generators and the grid sides of a Wind Farm System (WFS) based Direct Drive Synchronous Generator (DDSG). The control objectives such as Tracking the Maximum Power (TMP) from the WFS, pitch control, regulation of dc-link voltage, and reactive and active power generation at varying wind velocity are included. To validate the proposed control strategy, simulation results for 6-MW-DDSG based Wind Farm System are carried out by MATLAB-Simulink. Performance comparison and evaluation with Vector Oriented Control (VOC) are provided under a wide range of functioning conditions, three-phase voltage dips, and the probable occurrence of uncertainties. The proposed control strategy offers remarkable characteristics such as excellent dynamic and steady state performance under varying wind speed and robustness to parametric variations in the WFS and under severe faults of grid voltage.

Photovoltaic (PV) parameter estimation of a multicrystalline panel using developed iterative and non-iterative methods

Mathematical modeling of photovoltaic (PV) modules is essential for any performance optimization operation or diagnostic of the photovoltaic generator under changing environmental conditions. The limited data available are provided by commercial manufacturing datasheets. The accurately estimating of these parameters remains a challenge for researchers. There is great diversity in the models and the estimation methods i.e., iterative and non-iterative methods. In this paper we are interested in estimating the parameters of both complete (5-parameter) and simplified (4-parameter) single-diode PV models by non-iterative and iterative methods i.e., the Newton-Raphson and Halleys method. The aim is to predict the behavior of a multicrystalline Kyocera KC200GT module under real environmental conditions. A new parameter Series/Parallel Ratio (SPR) ranking photovoltaic modules is defined. Depending on the value SPR, we can neglect the series or shunt resistance of single-diode model without compromising accuracy. The proposed approach is a quick and non-iterative method that allows the estimation of PV parameters. It can be used in tracking applications of Maximum Power Point Tracking (MPPT) for on-line. The results obtained with non-iterative and iterative methods are compared with experimental data. The results are discussed in terms of precision and order statistical errors. They show the limits of the use of these approaches and their relevance. The method is verified by the simulation using MATLAB/Simulink environment.

Notice of Violation of IEEE Publication Principles Parameters identification of a Thin-Film photovoltaic panels

In this paper, our work consist to identify the parameters of both complete (5-parameter) and simplified (4-parameter) single-diode PV models by non-iterative and iterative methods. The objective is to predict the behavior of a Thin-Film module under real environmental conditions. A new parameter Series/Parallel Ratio (SPR) ranking photovoltaic modules is defined. According to the value SPR, we can neglect the series or shunt resistance of single-diode model without affect the accuracy. The results obtained with non-iterative and iterative methods are compared with experimental data. Simulations are performed in the MATLAB/Simulink environment.

Direct torque control method applied to the WECS based on the PMSG and controlled with backstepping approach

This paper proposes a Direct Torque Control (DTC) method for Wind Power System (WPS) based Permanent Magnet Synchronous Generator (PMSG) and Backstepping approach. In this work, generator side and grid-side converter with filter are used as the interface between the wind turbine and grid. Backstepping approach demonstrates great performance in complicated nonlinear systems control such as WPS. So, the control method combines the DTC to achieve Maximum Power Point Tracking (MPPT) and Backstepping approach to sustain the DC-bus voltage and to regulate the grid-side power factor. In addition, control strategy is developed in the sense of Lyapunov stability theorem for the WPS. Simulation results using MATLAB/Simulink validate the effectiveness of the proposed controllers.

Direct torque control strategy applied to the grid connected wind farm based on the PMSG and controlled with variable structure approach

This study proposes a direct torque control (DTC) and variable structure (VS) scheme for grid connected variable speed wind farm (VS-WF) based on the permanent magnet synchronous generators (PMSGs). The control strategy combines the DTC to achieve maximum power point tracking (MPPT) and nonlinear sliding mode (SM) control theory to sustain the DC-bus voltage and to regulate the grid-side power factor. Moreover, control strategies are developed in the sense of Lyapunov stability theorem for the VS-WF to satisfy multiple objectives. The performance of controllers is evaluated for fault conditions as well as for normal working conditions. The validity and the effectiveness of the proposed scheme are verified by simulation with Matlab/Simulink. Also, a comparison of simulation results based on the proposed algorithm and proportional-integral (PI) scheme shows that the proposed approach is superior.

Proposal of a backstepping control strategy for dynamic performance improvement of PMSG Wind Farm with common DC bus

This study proposes a control system design for Electrical Network Connected Wind Farm (ENCWF) using Direct Drive Permanent Magnet Synchronous Generator (DD-PMSG). The generators are connected to the power network by Voltage Source Converter (VSC) with a dc-link. The proposed scheme is based on Backstepping technique and regulates the powers exchanged between the ENCWF and the electric network to ensure a Maximum Power Tracking (MPT) of the wind system. The overall system model was implemented with MATLAB/Simulink. The proposed control technique is compared with Vector Control (VC) method. The effectiveness of the proposed control approach has been evaluated under various operating regimes of the ENCWF system and with three-phase to ground fault. The simulation results show a good performance of the proposed Backstepping strategy.

Nondestructive inverse approach for determining thermal and geometrical properties of internal defects in CFRP composites by lock-in thermography

Resolution approach of an inverse problem by lock-in thermography was developed for research geometric and thermal properties of internal defects, which are found in composites (CFRP), as depth, size, thermal conductivity and heat capacity. We have developed a new hybrid algorithm that uses the adaptive simulated annealing algorithm and the generalized patterns search algorithm to calculate the depth, size, thermal conductivity and heat capacity of defects. The gaps between results and literature values are very small, they do not exceed 4%. For optimizing the inverse problem objective function, the proposed algorithm has converged faster than literature algorithms.

Neural networks for back wall geometry reconstruction using the active thermography

In this work we propose a 3D reconstruction of a defect that exists in the inaccessible side of a material by an artificial neural network. We used a neural network that contains a single hidden layer with the sigmoid activation function to treat the standard thermal contrast deduced from the pulsed infrared thermography data. Three different data sets were used in the learning phase. The use of standard thermal contrast for training the neural network has significantly reduced the processed data number. This represented a considerable gain in data processing time and memory space. The 3D reconstructions were made by estimating the depth of each point of the defect geometry in the controlled material face. The differences between real and network estimated geometries are very low and are not exceeding 3%. The experimental results and the simulations by finite elements confirmed the performance of the presented method.