Electrical arc is a stochastic process; witch is the principal cause of power quality problems, i... more Electrical arc is a stochastic process; witch is the principal cause of power quality problems, including voltages dips, harmonic distortion, unbalance loads and flicker. So it is difficult to make an appropriate model for an EAF. The factors that effect EAF operation are the melting or refining materials, melting stage, electrode position (arc length), electrode arm control and short circuit power of the feeder. So arc voltages, current and power are defined as a nonlinear function of the arc length. In this article we propose our own empirical function of the EAF and model for the mean stages of the melting process. This study is important, because improvement of Electric Arc means high productivity (in tons/year) and lowest possible costs arising form energy consumption, electrode and refractory wear.
Zenodo (CERN European Organization for Nuclear Research), Jun 28, 2009
With the rapid advanced of technology, the industrial processes become increasingly demanding, fr... more With the rapid advanced of technology, the industrial processes become increasingly demanding, from the point of view, power quality and controllability. The advent of multi levels inverters responds partially to these requirements. But actually, the new generation of multi-cells inverters permits to reach more performances, since, it offers more voltage levels. The disadvantage in the increase of voltage levels by the number of cells in cascades is on account of series igbts synchronisation loss, from where, a limitation of cells in cascade to 4. Regarding to these constraints, a new topology is proposed in this paper, which increases the voltage levels of the three-cell inverter from 4 to 8; with the same number of igbts, and using less stored energy in the flaying capacitors. The details of operation and modelling of this new inverter structure are also presented, then tested thanks to a three phase induction motor.
Renewable & Sustainable Energy Reviews, Aug 1, 2019
Concentrator Solar Power (CSP) system is one of renewable solar energy, that has a crucial place ... more Concentrator Solar Power (CSP) system is one of renewable solar energy, that has a crucial place in the thermal production. The CSP is used for many different applications, as the turbine steam of electrical generator and cogeneration. These applications need thermal energy storage (TES) to allow the system to operate at nighttime. For this purpose, a new control system of CSP is proposed in this paper. The suggested system gives a new design of CSP where including a flexible collector and absorber. The proposed CSP does not control only the absorbed temperature but also aims to obtain the maximum CSP temperature under different illumination and improve the production of the plant. The CSP efficiency is discussed and the effects of including dynamic sensor and absorber in the proposed control system are highlighted and compared with SAM to show the technological advancement of the proposed design.
This paper proposes a new maximum power point tracking (MPPT) algorithm for photovoltaic (PV) sys... more This paper proposes a new maximum power point tracking (MPPT) algorithm for photovoltaic (PV) systems, which is tested in simulations and practical implementations. In the proposed PV-MPPT system, a new control strategy is applied to create two operating areas. In each area, the step-size is different in the function of the closeness to the MPP. Because of this strategy, some drawbacks of the conventional incremental conductance (IncCond) methods are eliminated. A single-ended primary-inductor converter (SEPIC) DC-DC converter is controlled with the proposed MPPT technique. The modified IncCond method is validated under simulation with test data, real data and real scenarios of solar irradiation. The results of the proposed approach show higher MPPT efficiencies and shorter convergence times than the conventional IncCond method even in rapidly changing conditions of solar radiation.
In this article, a solution to increase the reliability of powering the auxiliary equipment of po... more In this article, a solution to increase the reliability of powering the auxiliary equipment of power stations of major sources based on photovoltaic energy was examined. The investigations are carried out on the transformer station 220KV/90KV/60KV/30kV located at El Hadjar -Algeria, which uses the auxiliary service transformers 30/0.4 kV for its own power needs. Since the network itself provides this power, the station's low voltage equipment will felt any disturbance on the network (lack or drop of voltage, etc …). The function of the auxiliary service transformers 30/0.4 kV is to provide the energy required for the operation of network monitoring equipment (protection relays), high voltage (HV) controls (circuit breakers, disconnections, load adjuster), Signalizations, Telecommunications equipment (high frequency: HF network and optic fibers), Digital Control System. This whole system is intimately linked to the network. Hence the idea of an independent external source that will provide the energy necessary for its operation even in the case of a blackout. In addition, it will save the energy drawn from the grid for the needs of the interconnection transformer station.
International Journal of Electrical and Computer Engineering, May 26, 2011
The development of the power electronics has allowed increasing the precision and reliability of ... more The development of the power electronics has allowed increasing the precision and reliability of the electrical trainings, thanks to the adjustable inverters, as the Pulse Wide Modulation (PWM) five level inverters, which is the object of study in this article.The authors treat the relation between the law order adopted for a given system and the oscillations of the electrical and mechanical parameters of which the tolerance depends on the process with which they are integrated (paper factory, lifting of the heavy loads, etc.).Thus the best choice of the regulation indexes allows us to achieve stability and safety training without investment (management of existing equipment).
International Journal of Numerical Modelling-electronic Networks Devices and Fields, May 30, 2012
The commutating machines have a notable effect on the exchanges in brush-commutator contact area,... more The commutating machines have a notable effect on the exchanges in brush-commutator contact area, which is particularly obvious when determining the intensity of sparks located on the brush. With time, higher current density at the descending edge promote sparks excitation, which itself increases intensity of the electrical erosion, brush temperature and thus also the wear. So in order to make an analytical study of commutation phenomenon, the coupled circuit method was developed. Therefore, a generalized mathematical model of the commutation, for brush-commutator, is established and can be extended for any other types of commutation on the basis of electromagnetic field (e.g. transformers and phase shift transformer. This model provides a greater efficiency to explain the impact of the electromagnetic fluxes surrounding brush area (or switch), specially for the current transition of the commutation process. Successful commutation is defined as operation in normal service, with no serious damages to the commutator, brushes or switches due to sparking that might require abnormal maintenance. It is recognized that some visible sparking are not evidence of unsuccessful commutation. The recommendation to improve the commutation (to achieve longer brush life) is the implementation of the proposal (slotted brush), which provides a linear and a sweet transition of currents in the coils of commutation.
Renewable energy, especially solar photovoltaic (PV) panels, have been widely integrated into ene... more Renewable energy, especially solar photovoltaic (PV) panels, have been widely integrated into energy systems, indeed, this technology is eco-friendly and available almost everywhere. However, these systems exhibit some challenges in regards their performance. They must always track the maximum power point (MPP) to provide the highest power. This work investigates a novel maximum power point tracking (MPPT) procedure. In the suggested tracking system, a novel controller is applied to establish different operating regions. In both regions, the step is changed depending on the closeness to the MPP. Due to this technique, some disadvantages of the incremental conductance (IncCond) approach are avoided. The proposed method offers reliable and stable behaviour under rapidly changing atmospheric conditions. Moreover, it is easy as it does not need additional sensors. The theoretical assessment discussed in this investigation is validated by simulations via MATLAB/Simulink and experimental ...
Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transfo... more Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transformers are valuable equipment which makes a major contribution to the supply security of a power system. Consequently, it is of great importance to minimize the frequency and duration of unwanted outages of power transformers. So, Frequency Response Analysis (FRA) is found to be a useful tool for reliable detection of incipient mechanical fault in a transformer, by finding winding or core defects. The authors propose as first part of this article, the coupled circuits method, because, it gives most possible exhaustive modelling of transformers. And as second part of this work, the application of FRA in low frequency in order to improve and simplify the response reading. This study can be useful as a base data for the other transformers of the same categories intended for distribution grid.
International Journal of Applied Power Engineering, 2015
This paper deals the power control for three-level voltage source inverter NPC-VSI feeds the roto... more This paper deals the power control for three-level voltage source inverter NPC-VSI feeds the rotor of the doubly fed induction generator ‘DFIG’ based wind power generation system. This converter allows controlling the rotor voltage in magnitude and phase angle with a high flexibility and can therefore be used for active and reactive power control of DFIG. The control is especially designed to reduce the harmonic distortion of the generated currents and active power ripples of the classical control. In addition, it’s convenient for high power drive and variable speed generator applications with constant switching frequency. The detailed operation principle and simulation results for 3 MW of DFIG are also discussed.
2021 IEEE 1st International Maghreb Meeting of the Conference on Sciences and Techniques of Automatic Control and Computer Engineering MI-STA, 2021
For interconnection networks, stability and security of networks in each country are of major imp... more For interconnection networks, stability and security of networks in each country are of major importance for companies of generation and transmission of electrical energy and an objective of several research laboratories. For obvious technical and economic reasons, it is not possible to build networks free of malfunctions; they are particularly exposed at least to natural aggressions like lightning. Networks are therefore affected by disturbances that might affect the equipment durability and the quality of service provided and despite the existence of many traditional technical methods of stability, one always look for new methods that can improve the service quality. For this purpose, we will try in this thesis to address this issue through initially a thorough description of the interconnection network Algeria / Tunis then using the recorded incidents statistics, we focused our study on the disturbed line 220KV between AL Aouinette and Tajerouine with a proposed solution is to install a power transformer-type shifter "PST"
International Journal on Electrical Engineering and Informatics, 2018
In recent years, the solar energy has been considered as one of principal renewable energy source... more In recent years, the solar energy has been considered as one of principal renewable energy sources for electric power generation. However, the maximization of extracted power from PV system is a matter of concern as its conversion efficiency is low. Therefore, a maximum power point tracking (MPPT) controller is necessary in a PV system for maximum power extraction. This paper presents a new Maximum Power Point Tracking (MPPT) algorithm for Photovoltaic (PV) systems. The new method combines a novel strategy to identify the global maximum power point. In the proposed PV-MPPT system, a new control strategy creates two operating areas. In these two areas, the step-size changes adaptively from small step to large step. Thanks to this strategy all the drawbacks of the conventional technique have been eliminated. A SEPIC DC-DC converter was applied and controlled with MPPT techniques. The modified Incremental Conductance (IncCond) method is validated by simulation under real scenario of solar irradiation. Compared with conventional method, simulation results demonstrate the highest MPPT efficiency and the shortest convergence time of the proposed MPPT method even under fast changing of solar radiation.
Global Journal of Computer Sciences: Theory and Research, 2018
Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transfo... more Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transformers are valuable equipment which makes a major contribution to the supply security of a power system. Consequently, it is of great importance to disequilibria the three phases courant of power transformers. So, vector diagram Analysis is useful tool for reliable detection of incipient mechanical fault in a transformer, by finding winding or core defects. The authors propose this article, the coupled circuits method, because, it gives most possible exhaustive modelling of transformers. Measurement courant homopolaire in order to improve and simplify the response for à faults transformer.This study can be useful as a base data for the other transformers of the same categories intended for distribution grid. Keywords—Diagnostic; Short-Circuit; Transformer Faults; unbalanced current.
The lightning is a natural phenomenon, unforeseeable and behaves as a perfect generator of the el... more The lightning is a natural phenomenon, unforeseeable and behaves as a perfect generator of the electrical current which can reach the two hundred Ampere kilos and then it is a problem classified like a serious wonder for the researchers. The induced transient over-voltages in the electric systems following electromagnetic radiations of the lightning represent the most severe constraint and most significant on the electrical power networks.
The region of Adrar in Algeria is the windiest in the country; it is for this reason the electric... more The region of Adrar in Algeria is the windiest in the country; it is for this reason the electricity and gas company "Sonelgaz" has placed a wind farm of about 10 MW. Since it is a Saharan region, the wind is sandy, rich in silica that can damage the teeth of wind gearbox. The present work proposes a method which can make an early diagnosis of the broken tooth and its location in the gearbox, before the general breakdown. The modeling of defaults inside the turbine gearbox by symmetrical components technique is proposed successfully and for the first time in the field of diagnostics (usually this technique is used in the power grid lines short circuits analysis), associated with frequency response analysis. In addition, as it is impossible to install sensors at different parts, the increase in temperature and vibration inside the gearbox due to default, a sensor-less fault diagnosis based on the analysis of power signal generated by the wind turbine is presented and detailed. Furthermore, the peculiarity of this work is the modeling of unbalance forces caused by teeth failure on both the slow shaft and the fast shaft of the gearbox, which has never been considered before. It has been proven that this proposal allows a precise location of the broken tooth and the concerned gear inside the gearbox.
International Journal of Electrical Power & Energy Systems, 2012
The health of power transformer is important for the reliability of electrical power grid. There ... more The health of power transformer is important for the reliability of electrical power grid. There are various methods of evaluating the frequency spectrum to confirm the presence of an incipient fault. So, the accuracy of FRA method suggested by many researchers for predictive defections, has been discussed; and the robustness (efficiency, simplicity and fast diagnosis) of the proposed 2LFW as a substitution diagnostic process has been detailed and proved. It should be noted that the proposal is general and can be applied to different transformer, without any comparison to a reference signal. Furthermore the diagnosis can be done even for transformers in operation mode (in service), thus avoiding economical losses.
4th International Conference on Power Engineering, Energy and Electrical Drives, 2013
Lightning fascinates and frightens us. The considerable damage it causes to property and its unfo... more Lightning fascinates and frightens us. The considerable damage it causes to property and its unfortunate victims plainly demonstrate that the imaginary is based on a phenomenon that is very real and can be fairly well explained, but cannot be combated. Lightning is one of those natural events which catches people's imagination with its obvious violence and the destructive power attributed to it. Only modest attempts can be made to control its effects and the consequences. The aim of the present paper is to dissect, to better understand the phenomenon of lightning and thus make more tools to help for designing a more effective means of protection against lightning, when we discuss the properties of transient electromagnetic fields of lightning (TEMFL) through the characterization of components (Static Induction and Radiant) that form the three vectors of electromagnetic fields (electric vertical, electric horizontal and magnetic Azimuthal). The development of simulation code under Matlab "Sim-Lightning" helped us to reconstitute the allure of the spatio-temporal variation (TEMFL). By comparison of the results obtained by our code Sim-Lightning with others in the literature, experimental or simulated were given a very satisfactory approximation.
Generally, lightning damage has mainly been to home appliances and telephones, Towers and power t... more Generally, lightning damage has mainly been to home appliances and telephones, Towers and power transmission and generation equipment mal functions and damage due to strikes on power lines. With the adoption of wind power generation equipment, however, lightning damage is also increasing in this area. Through his dimensional characteristics and the wind power system is more exposed in the nature of all others. Lightning damage is the single largest cause of unplanned downtime in wind turbines and that downtime is responsible for the loss of countless megawatts of power generation. Wind turbines are high structures and, like tall towers, they not only attract downward flashes but initiate upward flashes as well. The rotation of the blades may also trigger lightning and result in considerable increase in the number of strikes to a wind turbine unit. Since wind turbines are tall structures, the lightning currents that are injected by return strokes into the turbines will be affected by reflections at the top, at the bottom and at the junction of the blades with the static base of the turbine. We present in this study our contribution to study of the impact of direct and indirect lightning strokes on wind turbines.
Electrical arc is a stochastic process; witch is the principal cause of power quality problems, i... more Electrical arc is a stochastic process; witch is the principal cause of power quality problems, including voltages dips, harmonic distortion, unbalance loads and flicker. So it is difficult to make an appropriate model for an EAF. The factors that effect EAF operation are the melting or refining materials, melting stage, electrode position (arc length), electrode arm control and short circuit power of the feeder. So arc voltages, current and power are defined as a nonlinear function of the arc length. In this article we propose our own empirical function of the EAF and model for the mean stages of the melting process. This study is important, because improvement of Electric Arc means high productivity (in tons/year) and lowest possible costs arising form energy consumption, electrode and refractory wear.
Zenodo (CERN European Organization for Nuclear Research), Jun 28, 2009
With the rapid advanced of technology, the industrial processes become increasingly demanding, fr... more With the rapid advanced of technology, the industrial processes become increasingly demanding, from the point of view, power quality and controllability. The advent of multi levels inverters responds partially to these requirements. But actually, the new generation of multi-cells inverters permits to reach more performances, since, it offers more voltage levels. The disadvantage in the increase of voltage levels by the number of cells in cascades is on account of series igbts synchronisation loss, from where, a limitation of cells in cascade to 4. Regarding to these constraints, a new topology is proposed in this paper, which increases the voltage levels of the three-cell inverter from 4 to 8; with the same number of igbts, and using less stored energy in the flaying capacitors. The details of operation and modelling of this new inverter structure are also presented, then tested thanks to a three phase induction motor.
Renewable & Sustainable Energy Reviews, Aug 1, 2019
Concentrator Solar Power (CSP) system is one of renewable solar energy, that has a crucial place ... more Concentrator Solar Power (CSP) system is one of renewable solar energy, that has a crucial place in the thermal production. The CSP is used for many different applications, as the turbine steam of electrical generator and cogeneration. These applications need thermal energy storage (TES) to allow the system to operate at nighttime. For this purpose, a new control system of CSP is proposed in this paper. The suggested system gives a new design of CSP where including a flexible collector and absorber. The proposed CSP does not control only the absorbed temperature but also aims to obtain the maximum CSP temperature under different illumination and improve the production of the plant. The CSP efficiency is discussed and the effects of including dynamic sensor and absorber in the proposed control system are highlighted and compared with SAM to show the technological advancement of the proposed design.
This paper proposes a new maximum power point tracking (MPPT) algorithm for photovoltaic (PV) sys... more This paper proposes a new maximum power point tracking (MPPT) algorithm for photovoltaic (PV) systems, which is tested in simulations and practical implementations. In the proposed PV-MPPT system, a new control strategy is applied to create two operating areas. In each area, the step-size is different in the function of the closeness to the MPP. Because of this strategy, some drawbacks of the conventional incremental conductance (IncCond) methods are eliminated. A single-ended primary-inductor converter (SEPIC) DC-DC converter is controlled with the proposed MPPT technique. The modified IncCond method is validated under simulation with test data, real data and real scenarios of solar irradiation. The results of the proposed approach show higher MPPT efficiencies and shorter convergence times than the conventional IncCond method even in rapidly changing conditions of solar radiation.
In this article, a solution to increase the reliability of powering the auxiliary equipment of po... more In this article, a solution to increase the reliability of powering the auxiliary equipment of power stations of major sources based on photovoltaic energy was examined. The investigations are carried out on the transformer station 220KV/90KV/60KV/30kV located at El Hadjar -Algeria, which uses the auxiliary service transformers 30/0.4 kV for its own power needs. Since the network itself provides this power, the station's low voltage equipment will felt any disturbance on the network (lack or drop of voltage, etc …). The function of the auxiliary service transformers 30/0.4 kV is to provide the energy required for the operation of network monitoring equipment (protection relays), high voltage (HV) controls (circuit breakers, disconnections, load adjuster), Signalizations, Telecommunications equipment (high frequency: HF network and optic fibers), Digital Control System. This whole system is intimately linked to the network. Hence the idea of an independent external source that will provide the energy necessary for its operation even in the case of a blackout. In addition, it will save the energy drawn from the grid for the needs of the interconnection transformer station.
International Journal of Electrical and Computer Engineering, May 26, 2011
The development of the power electronics has allowed increasing the precision and reliability of ... more The development of the power electronics has allowed increasing the precision and reliability of the electrical trainings, thanks to the adjustable inverters, as the Pulse Wide Modulation (PWM) five level inverters, which is the object of study in this article.The authors treat the relation between the law order adopted for a given system and the oscillations of the electrical and mechanical parameters of which the tolerance depends on the process with which they are integrated (paper factory, lifting of the heavy loads, etc.).Thus the best choice of the regulation indexes allows us to achieve stability and safety training without investment (management of existing equipment).
International Journal of Numerical Modelling-electronic Networks Devices and Fields, May 30, 2012
The commutating machines have a notable effect on the exchanges in brush-commutator contact area,... more The commutating machines have a notable effect on the exchanges in brush-commutator contact area, which is particularly obvious when determining the intensity of sparks located on the brush. With time, higher current density at the descending edge promote sparks excitation, which itself increases intensity of the electrical erosion, brush temperature and thus also the wear. So in order to make an analytical study of commutation phenomenon, the coupled circuit method was developed. Therefore, a generalized mathematical model of the commutation, for brush-commutator, is established and can be extended for any other types of commutation on the basis of electromagnetic field (e.g. transformers and phase shift transformer. This model provides a greater efficiency to explain the impact of the electromagnetic fluxes surrounding brush area (or switch), specially for the current transition of the commutation process. Successful commutation is defined as operation in normal service, with no serious damages to the commutator, brushes or switches due to sparking that might require abnormal maintenance. It is recognized that some visible sparking are not evidence of unsuccessful commutation. The recommendation to improve the commutation (to achieve longer brush life) is the implementation of the proposal (slotted brush), which provides a linear and a sweet transition of currents in the coils of commutation.
Renewable energy, especially solar photovoltaic (PV) panels, have been widely integrated into ene... more Renewable energy, especially solar photovoltaic (PV) panels, have been widely integrated into energy systems, indeed, this technology is eco-friendly and available almost everywhere. However, these systems exhibit some challenges in regards their performance. They must always track the maximum power point (MPP) to provide the highest power. This work investigates a novel maximum power point tracking (MPPT) procedure. In the suggested tracking system, a novel controller is applied to establish different operating regions. In both regions, the step is changed depending on the closeness to the MPP. Due to this technique, some disadvantages of the incremental conductance (IncCond) approach are avoided. The proposed method offers reliable and stable behaviour under rapidly changing atmospheric conditions. Moreover, it is easy as it does not need additional sensors. The theoretical assessment discussed in this investigation is validated by simulations via MATLAB/Simulink and experimental ...
Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transfo... more Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transformers are valuable equipment which makes a major contribution to the supply security of a power system. Consequently, it is of great importance to minimize the frequency and duration of unwanted outages of power transformers. So, Frequency Response Analysis (FRA) is found to be a useful tool for reliable detection of incipient mechanical fault in a transformer, by finding winding or core defects. The authors propose as first part of this article, the coupled circuits method, because, it gives most possible exhaustive modelling of transformers. And as second part of this work, the application of FRA in low frequency in order to improve and simplify the response reading. This study can be useful as a base data for the other transformers of the same categories intended for distribution grid.
International Journal of Applied Power Engineering, 2015
This paper deals the power control for three-level voltage source inverter NPC-VSI feeds the roto... more This paper deals the power control for three-level voltage source inverter NPC-VSI feeds the rotor of the doubly fed induction generator ‘DFIG’ based wind power generation system. This converter allows controlling the rotor voltage in magnitude and phase angle with a high flexibility and can therefore be used for active and reactive power control of DFIG. The control is especially designed to reduce the harmonic distortion of the generated currents and active power ripples of the classical control. In addition, it’s convenient for high power drive and variable speed generator applications with constant switching frequency. The detailed operation principle and simulation results for 3 MW of DFIG are also discussed.
2021 IEEE 1st International Maghreb Meeting of the Conference on Sciences and Techniques of Automatic Control and Computer Engineering MI-STA, 2021
For interconnection networks, stability and security of networks in each country are of major imp... more For interconnection networks, stability and security of networks in each country are of major importance for companies of generation and transmission of electrical energy and an objective of several research laboratories. For obvious technical and economic reasons, it is not possible to build networks free of malfunctions; they are particularly exposed at least to natural aggressions like lightning. Networks are therefore affected by disturbances that might affect the equipment durability and the quality of service provided and despite the existence of many traditional technical methods of stability, one always look for new methods that can improve the service quality. For this purpose, we will try in this thesis to address this issue through initially a thorough description of the interconnection network Algeria / Tunis then using the recorded incidents statistics, we focused our study on the disturbed line 220KV between AL Aouinette and Tajerouine with a proposed solution is to install a power transformer-type shifter "PST"
International Journal on Electrical Engineering and Informatics, 2018
In recent years, the solar energy has been considered as one of principal renewable energy source... more In recent years, the solar energy has been considered as one of principal renewable energy sources for electric power generation. However, the maximization of extracted power from PV system is a matter of concern as its conversion efficiency is low. Therefore, a maximum power point tracking (MPPT) controller is necessary in a PV system for maximum power extraction. This paper presents a new Maximum Power Point Tracking (MPPT) algorithm for Photovoltaic (PV) systems. The new method combines a novel strategy to identify the global maximum power point. In the proposed PV-MPPT system, a new control strategy creates two operating areas. In these two areas, the step-size changes adaptively from small step to large step. Thanks to this strategy all the drawbacks of the conventional technique have been eliminated. A SEPIC DC-DC converter was applied and controlled with MPPT techniques. The modified Incremental Conductance (IncCond) method is validated by simulation under real scenario of solar irradiation. Compared with conventional method, simulation results demonstrate the highest MPPT efficiency and the shortest convergence time of the proposed MPPT method even under fast changing of solar radiation.
Global Journal of Computer Sciences: Theory and Research, 2018
Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transfo... more Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transformers are valuable equipment which makes a major contribution to the supply security of a power system. Consequently, it is of great importance to disequilibria the three phases courant of power transformers. So, vector diagram Analysis is useful tool for reliable detection of incipient mechanical fault in a transformer, by finding winding or core defects. The authors propose this article, the coupled circuits method, because, it gives most possible exhaustive modelling of transformers. Measurement courant homopolaire in order to improve and simplify the response for à faults transformer.This study can be useful as a base data for the other transformers of the same categories intended for distribution grid. Keywords—Diagnostic; Short-Circuit; Transformer Faults; unbalanced current.
The lightning is a natural phenomenon, unforeseeable and behaves as a perfect generator of the el... more The lightning is a natural phenomenon, unforeseeable and behaves as a perfect generator of the electrical current which can reach the two hundred Ampere kilos and then it is a problem classified like a serious wonder for the researchers. The induced transient over-voltages in the electric systems following electromagnetic radiations of the lightning represent the most severe constraint and most significant on the electrical power networks.
The region of Adrar in Algeria is the windiest in the country; it is for this reason the electric... more The region of Adrar in Algeria is the windiest in the country; it is for this reason the electricity and gas company "Sonelgaz" has placed a wind farm of about 10 MW. Since it is a Saharan region, the wind is sandy, rich in silica that can damage the teeth of wind gearbox. The present work proposes a method which can make an early diagnosis of the broken tooth and its location in the gearbox, before the general breakdown. The modeling of defaults inside the turbine gearbox by symmetrical components technique is proposed successfully and for the first time in the field of diagnostics (usually this technique is used in the power grid lines short circuits analysis), associated with frequency response analysis. In addition, as it is impossible to install sensors at different parts, the increase in temperature and vibration inside the gearbox due to default, a sensor-less fault diagnosis based on the analysis of power signal generated by the wind turbine is presented and detailed. Furthermore, the peculiarity of this work is the modeling of unbalance forces caused by teeth failure on both the slow shaft and the fast shaft of the gearbox, which has never been considered before. It has been proven that this proposal allows a precise location of the broken tooth and the concerned gear inside the gearbox.
International Journal of Electrical Power & Energy Systems, 2012
The health of power transformer is important for the reliability of electrical power grid. There ... more The health of power transformer is important for the reliability of electrical power grid. There are various methods of evaluating the frequency spectrum to confirm the presence of an incipient fault. So, the accuracy of FRA method suggested by many researchers for predictive defections, has been discussed; and the robustness (efficiency, simplicity and fast diagnosis) of the proposed 2LFW as a substitution diagnostic process has been detailed and proved. It should be noted that the proposal is general and can be applied to different transformer, without any comparison to a reference signal. Furthermore the diagnosis can be done even for transformers in operation mode (in service), thus avoiding economical losses.
4th International Conference on Power Engineering, Energy and Electrical Drives, 2013
Lightning fascinates and frightens us. The considerable damage it causes to property and its unfo... more Lightning fascinates and frightens us. The considerable damage it causes to property and its unfortunate victims plainly demonstrate that the imaginary is based on a phenomenon that is very real and can be fairly well explained, but cannot be combated. Lightning is one of those natural events which catches people's imagination with its obvious violence and the destructive power attributed to it. Only modest attempts can be made to control its effects and the consequences. The aim of the present paper is to dissect, to better understand the phenomenon of lightning and thus make more tools to help for designing a more effective means of protection against lightning, when we discuss the properties of transient electromagnetic fields of lightning (TEMFL) through the characterization of components (Static Induction and Radiant) that form the three vectors of electromagnetic fields (electric vertical, electric horizontal and magnetic Azimuthal). The development of simulation code under Matlab "Sim-Lightning" helped us to reconstitute the allure of the spatio-temporal variation (TEMFL). By comparison of the results obtained by our code Sim-Lightning with others in the literature, experimental or simulated were given a very satisfactory approximation.
Generally, lightning damage has mainly been to home appliances and telephones, Towers and power t... more Generally, lightning damage has mainly been to home appliances and telephones, Towers and power transmission and generation equipment mal functions and damage due to strikes on power lines. With the adoption of wind power generation equipment, however, lightning damage is also increasing in this area. Through his dimensional characteristics and the wind power system is more exposed in the nature of all others. Lightning damage is the single largest cause of unplanned downtime in wind turbines and that downtime is responsible for the loss of countless megawatts of power generation. Wind turbines are high structures and, like tall towers, they not only attract downward flashes but initiate upward flashes as well. The rotation of the blades may also trigger lightning and result in considerable increase in the number of strikes to a wind turbine unit. Since wind turbines are tall structures, the lightning currents that are injected by return strokes into the turbines will be affected by reflections at the top, at the bottom and at the junction of the blades with the static base of the turbine. We present in this study our contribution to study of the impact of direct and indirect lightning strokes on wind turbines.
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