Génie électrique
Condition Monitoring of Rotating MachinesUsing Artificial Neural Networks andWavelet Transform
This paper deals with the application ofArtificial Neural Network (ANN) and Wavelet Transform(WT) for the prediction of the effect of unbalance fault onthe frequency components of vibration signature ofrotating machines. The suggested Technique is applied to realvibratory signals resulting from sensors placed on a test riginterfaced to a multi-channel data acquisition system OROS 25.The characteristic features of frequency domain vibrationsignals have been used as inputs to the ANN. Thesuggested ANN prediction model was implemented usingBayesian Evidence based training algorithm. It is foundthat the Bayesian Evidence based approach is much moreefficient than other techniques, which results in anaccurate detection of unbalance fault signals in theconsidered rotating machine. Voir les détails
Mots clés : Condition monitoring, Fault Diagnosis, ANN, wavelet, Vibration analysis, unbalance.
Study of a Solar Photovoltaic Regulator for Cathodic Protection Systems
Study of a Solar Photovoltaic Regulator for Cathodic Protection Systems Cathodic protection has divers known industrialapplications in buried or submerged pipes protection. The surrounding environment and the economic aspects are two decisiveparameters in the choice of the method of protection. When theenvironment conditions are well known and the method of protection properly mastered, the cathodic protection is generally cheap and efficient over a long period of time. The photovoltaic conversionrepresents a good issue to provide the needed autonomous energy forseveral applications. Since it has many applications, we are preciselyinterested in cathodic protection one. To well manage the use of thebattery, according to the desired application, it’s necessary to makean adequate choice of the type of the regulator of load. Theprevention opposes to the corrosion of the metallic deep pipes. Thus,a variable exit regulation for cathodic protection is studied. Thestabilization of the PV.G voltage guarantees a load of battery withfixed voltage. The charging current threshold takes into account oftwo parameters; the permanent measurement of the PV.G currentoutput and of the increase in its voltage. Voir les détails
Mots clés : corrosion, buried pipelines, photovoltaic System, cathodic protection, regulation, buck-boost converter, impressed current.
Condition Monitoring of Rotating Machines Using BayesianTrained Artificial Neural Networks
The paper deals with the application of Artificial Neural Network (ANN) for the prediction of the effect ofunbalance fault on the frequency components of vibration signature of rotating machines. The suggested Technique isapplied to real vibratory signals resulting from sensors placed on a test rig interfaced to a multi-channel dataacquisition system OROS 25. Several statistical characteristic features of frequency domain vibration signals havebeen used as inputs to the ANN. The suggested ANN prediction model was implemented using Bayesian Evidencebased training algorithm knowing for its established efficiency comparatively to other learning techniques. Theperformance of the suggested condition monitoring scheme was confirmed by the accurate results of detection ofunbalance fault signals in the considered rotating machine. Voir les détails
Mots clés : Condition monitoring, Fault Diagnosis, Artificial Neural Networks, Bayesian learning, Vibration analysis, unbalance, Rotating machines
Application of Wavelet Transform for Inner Race Fault (IRF) Diagnosis in Bearings of Rotating Machines
On-line vibration monitoring of Rotary Machines is a fundamental axis of development and industrialresearch. Its purpose is to provide knowledge about the working condition of machines at each moment withoutstopping the production line. This method allows avoiding the production losses related to breakdowns and reducingoverall maintenance costs. Bearing fault diagnosis is important in vibration monitoring of any rotating machine.Early fault detection in machineries can save millions of dollars in emergency maintenance cost. In this paper we areinterested to the vibration signal processing by Application of Wavelet Transform for Inner Race Fault (IRF)Diagnosis in bearings, the suggested Technique is applied to real vibratory signals obtained from the Case WesternReserve University Bearing Data Centre. From the monitoring results, the effectiveness of the Wavelet Transformmethod was proven. Voir les détails
Mots clés : Vibration analysis, Fault Diagnosis, Rotating machines, Wavelet transform, Envelope Detection
An Improved Method for Gear Fault diagnosis
Envelope analysis is especially suitable for fault diagnosis inducing periodic shocks or amplitude modulations such as gears and bearings and has been applied widely for mechanical fault detections over the last few decades. However, a critical limitation of this technique is that it requires a prior knowledge on filtering band. Due to this drawback, detecting machine defects at the incipient stage when defect-characteristic components are weak in amplitude and without a distinctive spectral pattern poses a challenge to the conventional enveloping spectral analysis technique .In order to overcome this limitation, this work gives a new signal processing approach for gear faults diagnosis based on Hilbert Transform (HT) and Fast Fourier Transform (FFT). It is applied on real measurement signals collected from an experimental vibration system. The monitoring results indicate that the proposed method improves the gear faults diagnosis relatively to other common techniques. Voir les détails
Mots clés : Vibration signal Analysis, gear Fault diagnosis, Hilbert Transform (HT), Envelope Analysis (EA), Fast Fourier Transform (FFT).
Dynamic Response of a Stand Alone DC Side Wind Energy Conversion System with Battery Energy Storage to a Wind Gust.
The study concerns particularly the DC side of the wind system, the continuity of the AC one being already studied in. Then,this work elaborates an analysis of the DC components, particularly the system conversion and storage of the wind system conversion. Indeed, the battery is a storage buffer essential in our case for isolated network. We emphasize its importance by evaluating its various features. The AC study concerned the analysis and simulation of a low speed Permanent Magnet Synchronous Generator (PMSG) driven by a vertical wind turbine through a Pulse-Width Modulation (PWM) voltage inverter. Renewable resources are in constant fluctuation. Therefore, in order to maximize the efficiency of the renewable energy system it is necessary to track the maximum power point of the input source. In this system, the maximizing is assured while considering the optimal power curve as load characteristic, with the knowledge of the turbine characteristic Cp (λ). The study was accomplished on MATLAB/Simulink and Script platforms. Voir les détails
Mots clés : Permanent Magnet Synchronous generator, mdel, DC side, Storage, Small Wind Turbine
Dynamic Response of a Stand Alone AC Side Wind Energy Conversion System
This Paper consists on the study of one part of wind energy system conversion, its ACside. Renewable resources are in constant fluctuation. This situation could put in peril the energizing efficiency towards a given demand requirement. Therefore, in order to maximize the efficiency of the renewable energy system, it is necessary to track the maximum powerpoint of the input source, a study established under MATLAB/Simulink platform. For the wind system, the maximizing is assured while considering the optimal power curve as load characteristic, with the knowledge of the turbine characteristic C_p (λ).Then, this work elaboratesthe analysis and simulation of a low speed Permanent Magnet Synchronous Generator (PMSG) driven by a vertical wind turbine through a Pulse-Width Modulation (PWM) voltage inverter, independently of the DC components of the wind system conversion, usingMATLAB computer simulation. Voir les détails
Mots clés : Wind, Optimal load characteristic, Compensation decoupling, IP regulator, Permanent Magnet Synchronous Generator.
PV Cell Temperature/ PV Power Output Relationships Homer Methodology Calculation
Because of the intermittent solar irradiation whichhighly influences the resulting energy production, the majoraspects in the design of PV power generation systems are thereliable power supply of the consumer under varyingatmospheric conditions and the corresponding total system cost.Thus it is necessary to select the number of PV modules andbatteries, and their installation details such as the power will beuninterruptedly supplied to the electrical load, andsimultaneously the minimum system cost would be achieved.But it’s especially so judicious to take into account the wholesystem parameters such as cell temperature, a task ensured byseveral software tools as Homer from the NREL Laboratory.As known, meteorological parameters especially the arraytemperature, do not remain constant the whole day long, butchange considerably. Then, it is worth investigating the influenceof the daily average temperature variation on the predictedperformances of the optimized system.It’s so important to seize how such software proceeds to get around any result calculation and a possible problem at the same time.So, the goal achieved through this study is to investigate theinfluence of the cell temperature and head changing effects onthe system performances. So an approach by a mathematical formalism is then indispensable. Voir les détails
Mots clés : solar layer, PV cell temperature, PV power output, mathematical formulation, calculation, Homer.
MPPT Control of a Small PV Generation System under Diverse Weather Conditions
The power induced in the photovoltaic modules is influenced by the intensity of solar cell irradiation, temperature of solar cells and moreover by the load. Therefore, to maximize the efficiency of the renewable energy system, it is necessary to track the maximum power point of the input source. In this work, we tie to present the constituent of a weak power PV chain dedicated to the storage on battery. The battery bank is connected to the DC network via a DC/DC boost converter, called the storage converter, used for controlling the network.Indeed, the battery is only imperative buffer storage in this case. The PV units are connected to the DC network via its own DC/DC converter, called PV converter, to ensure the required power flow. The purpose of the proposed model is the simulation of the complete system behavior from the electric and energy point of view. A maximum power point tracker (MPPT) scheme is applied through the boost converter to improve the energy conversion efficiency. Fuzzy algorithm based on linguistic rules describing the operator’s control strategy is applied to control the step-up converter for MPPT. On the other hand, Fuzzy logic control based on coarse and fine mode is incorporated in order to reduce not only the time required to track the maximum power point but also power fluctuation. A confrontation with a P and O method performed. Another fuzzy battery-charge controller is also applied. Simulation results show that the proposed fuzzy controller exhibits a better performance than the controller based upon the P and O method. Voir les détails
Mots clés : Photovoltaic, simulation, MPPT; DC-DC converter, Fuzzy controller
AC Corrosion Induced by High Voltage Power Line on Cathodically Protected Pipeline
The implications of the influence of alternating currents on buried pipelines are of great concern to all pipeline owners in world. The relevance of the interference is always increasing for operational personnel and for the protection of buried metallic structures from corrosion. The paper studies the electromagnetic interference problem between an existing high voltage power line and a newly designed underground pipeline cathodically protected. Induced voltages and currents are evaluated for steady state operating conditions of the power line. It is found that on pipelines suffering from A.C. interference traditional pipe-to-soil potential measurements do not guarantee efficient cathodic protection against corrosion. A specific approach to assess the effectiveness of cathodic protection should be adopted. Voir les détails
Mots clés : Induced Voltages, Electric Power Transmission Lines, pipeline, AC Corrosion, cathodic protection, soil resistivity, AC interference