Electrotechnique
Novel and simplified model representing Current-Output Phase-Shift Full-Bridge DC-DC LCLC Resonant Converter in Arc Welding Application
In this paper, a novel and simplified model representing current-output phase-shift full-bridge DC-DC LCLC resonant converter in arc welding application is thoroughly presented. First, a switched model written in state space representation and featuring a bilinear form is proposed. The latter facilitates the derivation of both the reduced and full order averaged models in continuous conduction mode (ROAM and FOAM). Although the FOAM can be employed in linear or nonlinear control schemes and the derivation of steady state behavior, in this paper the ROAM is considered in designing both voltage mode control and current mode control by using the classical PID and the fractional order PID controllers. Simulation confirms that the switched model, ROAM and FOAM are quite accurate compared to the circuit simulation using SimPowerSystem toolbox of MATLAB/SIMULINK. Results clearly showed that depending on the switching frequency, the proposed topology can be applied either in constant voltage characteristic or dropped characteristic welding machines fulfilling either zero current Switching (ZCS) or zero voltage switching (ZVS). Besides, the fractional order PID controller seems to be more adapted for arc welding application than its traditional version. Voir les détails
Mots clés : LCLC resonant converter, switched model, reduced order averaged model, full order averaged model, arc welding, FOPID, IGWO
Particle Swarm Optimization of Fuzzy Fractional PDµ+I Controllerof a PMDC Motor for Reliable Operation of Wire-Feeder Units ofGMAW Welding Machine
In this article, we consider the development of an optimal control approach based on fuzzy fractional PDµ+I controller to improve thespeed error-tracking and control capability of a permanent magnet DC Motor (PMDC) driven wire-feeder systems (WFSs) of gas metal arc welding(GMAW) process. The proposed controller employs an optimized fractional-order proportional derivative + integral (PDµ+I) controller that serves toeliminate oscillations, overshoots, undershoots and steady state fluctuations of the PMDC motor and makes the wire-feeder unit (WFU) has fast andstable starting process as well as excellent dynamic characteristics. The fixed controller parameters are meta-heuristically selected via a particleswarm optimization (PSO) algorithm. Numerical simulations are performed in MATLAB/SIMULINK environment and the performance of the proposedfuzzy fractional PDµ+I controller is validated. The simulation tests clearly demonstrate the significant improvement rendered by the proposed fuzzyPDµ+I controller in the wire-feeder system's reference tracking performance, torque disturbance rejection capability and robustness against modeluncertainties. Voir les détails
Mots clés : GMAW process, Wire-feeder System (WFS), fuzzy fractional PDµ+I controller, Particle Swarm Optimization (PSO) algorithm
Optimal Tuning of Fractional Order Proportional-Integral-Derivative Controller for WireFeeder System Using Ant Colony Optimization
The goal of this work is to present a robust optimal control approach, in order to improve the speed error-tracking and control capability of a permanent magnet DC Motor (PMDC)driven wire-feeder systems (WFSs) of gas metal arc welding (GMAW) process. The proposed speed controller employs an optimized fractional-order proportional + integral+ derivative (FOPID) controller that serves to eliminate oscillations, overshoots, undershoots and steady state fluctuations of the PMDC motor and makes the wire-feeder unit (WFU) has fast and stable starting process as well as excellent dynamic characteristics. The fixed controller parameters are meta-heuristically selected via an ant colony optimization (ACO) algorithm. Numerical simulations are performed in Matlab/Simulink environment and the performance of the proposed ACO-FOPID controller is validated. The simulation results clearly demonstrate the significantimprovement rendered by the proposed approach in the wire-feeder system's reference tracking performance, torque disturbance rejection capability, and transient recovery time. Voir les détails
Mots clés : gas metal arc welding process, wire-feeder system, fractional-order-proportionalintegral-derivative controller, ant colony optimization algorithm
New Optimal Control of Permanent Magnet DC Motor for Photovoltaic Wire FeederSystems
This article aims to improve the permanent magnet DC (PMDC) motor performance forphotovoltaic (PV) wire-feeder systems (PVWFSs) of arc welding machines. Theconsidered technique is designed by direct speed control based on optimal Fractional-orderFuzzy PID FO-Fuzzy-PID controller. The purpose is to ensure optimal control of wire feedspeed reference to reduce torque ripples and hence, the performance of the WFS isimproved. The dynamic reaction of the proposed solar PVWFS relies upon the scalingfactors of FO-Fuzzy-PID controller, which are optimized by using teaching-learningalgorithm based on Particle Swarm Optimization (PSO) method. The maximum powerpoint tracking (MPPT) is achieved using an intelligent FO-Fuzzy-PID current controllerbased Perturb and Observe (P&O) MPPT algorithm. The PVWFS system incorporatingthe proposed method is tested and compared with the conventional PID control schemeunder different weather conditions. The simulation of the proposed system byMATLAB\SIMULINK is carried out. The simulation results indicate the effectiveness ofthe considered control strategy in terms of the reduction in torque oscillations, optimizingelectrical power and wire feed speed. Voir les détails
Mots clés : Solar photovoltaic (PV) module, wire feeder systems (WFSs), DC-DC buck converter, MPPT control, FO-Fuzzy PID controller, Particle Swarm Optimization (PSO) algorithm
Fault tolerant control of energy processes
This work deals with the control of energy systems subject to faults. The objective is toaccommodate faults by the design of a control law that takes into account the existence ofinternal faults and dysfunctions caused by external environment.Energy systems are characterized by the dependence of their performance on energyefficiency, the total efficiency is the result of the operation of elementary energy processesto verify the final objective which is the production of energy in its final form. Thesupervision of these processes and tolerance to faults allow the improvement of individualperformances and the achievement of global efficiency at a lower cost.In this context, renewable energy conversion processes are characterized by the aspect oftheir dependence on climatic conditions and direct exposure to outdoor environment,resulting in the occurrence of different types of faults and dysfunctions. Solar photovoltaicrenewable energy generation systems are considered in this work as they dominaterenewable electricity capacity expansion. The study of the effect of various abnormalevents and degraded operating modes of solar photovoltaic systems is performed and afault-tolerant control law is proposed to enhance the efficiency of these energy processes.A reconfiguration of controller is designed to switch between an improved current-basedparticle swarm optimization technique and the incremental conductance algorithm.Practical implementation of the proposed approach shows excellent performance in realoperating conditions when compared to traditional maximum power point algorithms. Voir les détails
Mots clés : fault-tolerant control, energy systems, renewable energy, Solar energy, Photovoltaic, Maximum Power Point Tracking, Particle Swarm Optimization
Electric Field Distribution in point-insulating barrier-Plane System using experimental and Theoretical method
The present paper deals with the influence of insulating barriers on the breakdown and the electric field distribution in the Point –insulating barrier- plane air gap system. An experimental investigation on the influence of different parameters such as gap distance between electrodes and barrier dimensions, under AC voltage, have been studied. The results show that the width and thickness of the insulating barrier effect the electric field variation which increases with increasing applied voltage. The experimental results are compared with a numerical model. Voir les détails
Mots clés : Electric field, Finite Element Method, breakdown voltage, insulating barrier, point- plane system
Diagnosis Method for GTO Open Switch FaultApplied to Reconfigurable Three-Level 48-PulseSTATCOM
In the recent years, several research worksare focusing on the use of STATCOM in electrical net-works because it is used to regulate the voltage, to im-prove the dynamic stability of the power system be-sides allowing better management of the power ?ow.All these positive tasks have guaranteed an importantposition of STATCOM within a family of Flexible Al-ternating Current Transmission System (FACTS). Inthis paper study, the control and operation of a threelevels 48-pulse GTO based STATCOM is implementedwith series connected transformers. The system may,unfortunately, be prone to GTO switch faults and there-fore may a?ect reactive power transiting. In this pa-per, a new diagnostic approach is proposed based onthe Single-Sided Amplitude Spectrum (SSAS) methodof the three-leg converter currents for detection and lo-calization of open-circuit faults. The integration of theSTATCOM recon?gurable fault tolerant to the systemis also considered to ensure service continuity. Sev-eral results are presented and discussed in this paperto illustrate the performance of the STATCOM fault-tolerant diagnostic. Voir les détails
Mots clés : Detection, diagnosis, FACTS, GTO, open switch fault, recon?guration, SSAS, STATCOM
CONTRIBUTION TO RECONFIGURATION OF FAULT-TOLERANT INVERTER APPLIED TO THE WIND PARK CONNECTED TO THE ELECTRICAL NETWORK
This paper proposes a new diagnostic technique based on Park vectors associated with polar coordinates for the detection and location of open circuit (OC) faults, as well as the integration of fault-tolerant reconfigurable inverter in order to enable continuity of service of the wind farm system. The model used is that of a variable speed wind turbine coupled to a double-fed induction generator (DFIG) connected to the power grid via a fault-tolerant converter to improve performance after the appearance of the fault. This converter is used based on IGBT to obtain an acceptable accuracy with high switching frequencies. This model is well suited for the observation of harmonics and the dynamic performance of the control system over relatively short periods of time (typically hundreds of milliseconds to one second). This method allows extracting the maximum wind energy during a low wind speed by optimizing the turbine speed while minimizing the mechanical stress on the turbine during gusts of wind. To illustrate the diagnostic improvement of fault-tolerant inverter open circuit faults, several results are presented and discussed in this article. Voir les détails
Mots clés : DFIG Turbine, Inverter, diagnosis, Detection, Location, Reconfiguration, fault, Open-Circuit, IGBT
A Robust Adaptive Fuzzy Fast Terminal Synergetic Voltage Control Scheme for DC/DC Buck Converter
In this paper, an adaptive fuzzy fast terminal synergetic voltage control scheme for DC/DC buck converter is proposed based on recently developed synergetic theory and a terminal attractor method. The advantages of presented synergetic control include the characteristics of finite time convergence, insensitive to parameters variation and chattering free phenomena. Rendering the design more robust, fuzzy logic systems are used to approximate the unknown parameters in the proposed controller without calling upon usual model linearization and simplifications. Taking the DC/DC buck converter in continuous conduction mode as an example, the algorithm of proposed synergetic control is analyzed in detail. All the simulation results demonstrate the effectiveness and the high dynamic capability of the proposed AF-FTSC control technique over the FTSC strategy. Voir les détails
Mots clés : synergetic control, fuzzy logic system; terminal technique; finite time convergence; DC/DC buck converter.
Predictive Control of a Grid Connected PV System Incorporating Active power Filter functionalities
This article proposes a multifunction of a double stage grid connected photovoltaic (PV) system, with insertion the active power filter (APF) functionalities. This system is used to compensate the harmonics currents, compensate reactive power, supply the nonlinear loads and inject the PV system's active power into grid. This study is based on grid side, a perturb and observe algorithm is used to extract the maximum power point tracking (MPPT) from the PV array regardless of solar irradiance. On the grid side, a modified instantaneous active and reactive power theory (P-Q) based on a multi-variable filter (MVF) is applied to correctly identify the harmonics currents reference under distorted source voltage condition, also a modified predictive current control (PCC) algorithm is used to generate the switching signals for the source voltage inverter in order to ensure compensate reactive power and harmonic currents, feed the non linear load and inject the surplus of active powerinto the grid. In Matlab/Simulink™ software environment, the performance of the proposed control scheme is investigated under load change and irradiance change conditions. Simulations results demonstrate that the proposed PCC of the APF ensure a manage of active power exchanges with the grid with power factor correction. Furthermore, the grid current recovers its sinusoidal waveform with a total harmonic distortion (THD) meet to IEEE-519 standard. Voir les détails
Mots clés : Photovoltaic system (PV), activ power filter (APF), Predictive current control (PCC), active and reactive power theory (P-Q), multivariable filter (MVF), total harmonic distortion (THD)