Search

An ultrahigh step-down converter with a low number of semiconductor devices is presented in this article. Important features of this converter are simple structure with low size and cost, low voltage and current stress on components, low output current ripple, and low conduction and switching losses. In this converter, the power switches are turned on under zero current switching (ZCS) condition, whereas the output diodes commutate under ZCS condition without any auxiliary circuit. Thereby, in addition to the converter efficiency improvement, the diodes reverse recovery problem is alleviated. The proposed topology has employed a two-phase interleaved structure to reduce current stress, three windings coupled inductors to further decrease the voltage gain, and two series capacitors to diminish the voltage stress on the semiconductors elements and recover the leakage inductances energy. The experimental results of an implemented prototype are provided to evaluate the effectiveness of the proposed topology at 100 kHz and 200 W, which converts a 400-V input voltage into a 12-V output voltage.

Reliability of power electronics is one most critical challenge to face in order to improve the reliability of wind turbine system (WTS). As the power of the wind turbine is increasing, different topologies of power converters are developed for wind turbine applications. The three-level Neutral-Point Clamped (NPC) converter is widely used in WTS, since it has many advantages like a large output capacity, high output voltage and low current Total Harmonic Distortion (THD). However, the topology of these converters has a large number of switches which are fragile components. Open circuit is one of the most common failures in these converters and causes considerable economic damage in wind power systems. This paper presents an open-circuit fault diagnosis method for a three-level NPC inverters based on current and charge distortion in the output of the inverter. The operation of the NPC inverter under normal and open-circuit fault are analyzed. Simulations results of the converter control and the fault diagnosis method are presented and discussed.

The load flow into hybrid grid needs to manage the level of electrical power generations and storage energy. The efficient control of energy storage to match the fluctuation of load demand and estimated generation of wind energy is the main contribution of this paper. The strategy used to control the constant time of frequency approach applied to batteries depend on the operation condition of wind farm turbine system. The charge and discharge of batteries is consider on the control strategy to keep its state of health and deliver the energy at bad weather conditions. The obtained results of proposed control are adopted to manage the efficient performance of the hybrid wind system.

Mining sites that combine energy-intensive operations with community living in areas remote from the electricity grid are increasingly developing dedicated micro-grids. Fossil oil gensets hybridization with renewable energy resources has gained momentum. Difficulties in assessing performance are experienced by operators who wish to benefit from improved performances. The designers of such systems also need additional knowledge to anticipate the solutions of the particular problems related to the power plant’s implementation area characteristics. The proposed approach gives more suitable tools on the effectiveness evaluation of hybridized microgrid, combining a Heavy Fuel Oil (HFO) thermal power station with photovoltaic generator powering mine activities in the Sahelian area. The authors provide key analyses and improvement factors by seasonal behavioral modelling (SBM) of the fuel consumption of the gensets related to the overall irradiance dynamics of the PV array. Several years of data analysis results have been integrated for sharper considerations on the transient interactions impact of the PV/Diesel Hybrid Power Plant operation. The results of simulations carried out using the proposed new models, including the case of an extended system with storage unit, have been used to evaluate the levelized cost of energy, and to discuss competitiveness. This very relevant approach provides additional knowledge for designers and energetic effectiveness analysts.

With the goals set for sustainable development and renewable energy technologies, major advancements have been observed in the domain of multi-source systems [...]

International audience; A freight transport hybrid electric boat (HEB) is investigated in order to improve the dynamic response of the boat during the rapid variations of the onboard load such as the acceleration/deceleration, the braking, the docking maneuvers operations, and the goods package lifting system. The propulsion architecture is based on a variable-speed diesel generator (DG) used as the main energy source, with the multiple energy storage system based on the supercapacitors (SC) and the batteries which are used in the HEB to answer the intermittent power due to a sudden load change. This solution compensates the fluctuations from the load by reducing their impacts for diesel engine. The variable-speed diesel generator is connected to the dc-bus using three-phase controlled rectifier to manage dc-bus voltage. The SC and the batteries are linked to dc-bus through two bidirectional dc/dc converters to control the high-frequency component independently to those of the average-frequency component. Two identical thrusters are, respectively, placed in the front of and the behind of the boat to emulate the propulsion operations. The HEB power demand includes the thruster's requirements and embedded appliances (elevator, package lifting system, heating system, TV, computer, and electronics device for navigation). The main contribution of this paper is focused on the HEB dynamic response improvement during the rapid variations of the load using the SC and the batteries. Other significant contributions are based on the LiFePO4-battery modeling using solartron analytical impedance spectroscopy and the load current sharing between the DG and the SC/batteries, where the high-frequency component of the load is assigned to SC due to its fast dynamic response and that of the average frequency is allocated to the batteries. The proposed energy management strategy is verified by the simulation and experimental tests in reduced scale using a specific driving cycle of the HEB for one trip.

Wind energy is an alternative to meet the growing energy demand. Control of wind turbines should help the reliability and stable operation of the power grid. Furthermore, they should respect the technical requirements according to the grid codes to inject the wind energy into the grid. In this paper, a well-known field-oriented control (FOC) method and a new control method based on the flatness properties (FBC) are presented and compared. These control methods are applied to a wind energy conversion system (WECS), which connects a variable-speed wind turbine (WT) based on a permanent magnet synchronous generator (PMSG) to the grid via a back-to-back converter. The main aim of both control methods is to extract the maximum power from the wind. For this purpose, the mathematical model of each subsystem, i.e., WT, PMSG, and electrical grid, is presented. To evaluate and to compare the dynamic behavior of the high-power wind energy conversion system, it is modeled and the control strategies are developed using SimPowerSystems Toolbox in MATLAB. The simulation results obtained in the time domain show that the FBC performs better at managing the energy in the studied system. Indeed, the proposed FBC is a high bandwidth control method with only one closed-loop control, which leads to a high dynamic performance. Therefore, that strategy can be used to provide ancillary services such as frequency control and spinning reserves according to the grid codes.

In this paper, a bidirectional zero voltage switching (ZVS) resonant converter with narrow control frequency deviation is proposed. Wide input–output voltage range applications, such as flywheel or supercapacitors storage units are targeted. Due to symmetrical topology of resonant circuit interfaces, the proposed converter has similar behavior in bidirectional operating mode. We call it Dual Active Bridge Converter (DABC). The proposal topology of the converter is subjected to multi resonant circuits which make it necessary to study with multiscale approaches. Thus, first harmonic approximation and use of selective per unit parameters are established in (2) Methods. Then, the forward direction and backward direction of power flux exchange are detailed according to switching sequences. Switching frequency control must be completed within a narrow range. So, the frequency range deterministic parameters are emphasized in the design procedure in (3) Methods. A narrow range of switching frequency and a wide range voltage control must be ensured to suit for energy storage units, power electronic devices capabilities and electromagnetic compatibility. A 3 kW test bench is used to validate operation principles and to proof success of the developed design procedure. The interest of proposed converter is compared to other solutions from the literature in (4) Results.

The main challenges for renewable energy integration in electrical grid system are their variability and prediction. Tidal renewable energy is considered low variability in comparison to wind energy generation and due to tides regular periodicity, it is often quoted as predictable. This paper presents the modeling of Orkney's distribution network with the integration of tidal energy. This multi-physics model is based on the graphical formalism tool, Energetic Macroscopic Representation (EMR). This tool has been used to analyze the Tidal energy conversion (TEC) system based on the behavior of permanent magnet synchronous machine (PMSM). The daily, monthly and yearly variations of marine water speed in Orkney were observed. The EMR has been efficiently used in the representation of Orkney energy system integration of Orbital O2 tidal systems, and showing its effectiveness to adopt the control strategy. More precisely, the data of current water profile for 2009 has been chosen from 10 years big data to test the adopted deduced control technique. The methodology of this tool is described in details and the simulation results obtained in MATLAB environment are presented.

International audience; In recent years with higher levels of wind power penetration to the grid, beside active power production, Wind Energy Conversion Systems (WECS) are controlled to provide ancillary services such as load balancing and grid power factor correction. Among several converter topology used to design the power converters connecting the Wind Turbine System (WTS) to the grid, the Neutral-Point-Clamped (NPC) topology is attracting the interest of researchers. However, the NPC converter suffers from the Neutral Point (NP) voltage unbalance and, as the case of all the PWM converters, generates the undesirable Common Mode Voltage (CMV). Therefore this paper proposes a predictive current control method for a threelevel NPC grid connected converter capable of simultaneously compensating the problems of : i) Load balancing and power factor correction, ii) NP voltage regulation and iii) CMV reduction. The simulation results show the good performance and the clear capacity of the proposed method to achieve simultaneously the three objectives.

This paper presents a new approach for supercapacitors characterization using impedance spectroscopy taking into account the dynamics constraints, such as temperature, current ripple rate and cycling frequency. This characterization is done using Modulab XM test bench. The main goal of this study is to show the parameters evolution which can serve to find out the supercapacitor energetic performances. From experimental data, the parameters of the supercapacitor (series resistance and capacitance) are calculated from the Nyquist diagrams. The contribution of this paper is focused on the parameters dependence study according to the dynamics constraints listed previously (temperature, current ripple rate and the cycling frequency) and their combination (temperature-current ripple rate and current ripple rate-cycling frequency). Finally, the experimental results, which show a dependence of series resistance (ESR) and capacitance (C) compared to these constraints, are presented.

International audience; This paper presents a new approach for supercapacitors (SCs) characterization using temporal method taking into account the influence of the dynamics constraints, such as number of cycles and rms value of DC-current ripple. This characterization is done using supercapacitor cycler BT2000 test bench. From experimental data, the parameters of the supercapacitor (SC) (series resistance and capacitance) are calculated from the voltage response compared to current input. The contribution of this paper is focused on the parameters dependence study according to the dynamics constraints listed previously (number of cycles and rms value of DC-current ripple). Finally, the experimental results, which show a dependence of series resistance (ESR) and capacitance (C) compared to these constraints, are presented.; Cet article présente une nouvelle approche pour la caractérisation des supercondensateurs (SC) utilisant la méthode temporelle prenant en compte l'influence des contraintes dynamiques, telles que le nombre de cycles et la valeur efficace de l'ondulation du courant continu. Cette caractérisation est effectuée à l'aide du banc d'essai du cycleur à supercondensateur BT2000. À partir de données expérimentales, les paramètres du supercondensateur (SC) (résistance série et capacité) sont calculés à partir de la réponse en tension par rapport à l'entrée de courant. La contribution de cet article est centrée sur l'étude de la dépendance des paramètres en fonction des contraintes dynamiques listées précédemment (nombre de cycles et valeur efficace de l'ondulation du courant continu). Enfin, les résultats expérimentaux, qui montrent une dépendance de la résistance série (ESR) et de la capacité (C) par rapport à ces contraintes, sont présentés.

In this paper, a hybrid electric power supply system for an electric vehicle (EV) is investigated. The study aims to reduce electric stress on the main energy source (fuel cell) and boost energetic performances using energy sources with high specific power (supercapacitors, batteries) for rapid traction chain solicitations such as accelerations, decelerations, and braking operations. The multisource EV power supply system contains a fuel cell stack, a lithium batteries module, and a supercapacitors (Sc) pack. In order to emulate the EV energy demand (wheels, weight, external forces, etc.), a bidirectional load based on a reversible current DC-DC converter was used. Fuel cell (Fc) stack was interfaced by an interleaved boost converter. Batteries and the Sc pack were coupled to the DC point of coupling via buck/boost converters. Paper contribution was firstly concentrated on the distribution of energy and power between onboard energy sources in consonance with their dynamic characteristics (time response). Second contribution was based on a new Sc model, which takes into consideration the temperature and the DC current ripples frequency until 1000 Hz. Energy management strategy (EMS) was evaluated by simulations and reduced scale experimental tests. The used driving cycle was the US Federal Test Procedure known as FTP-75.

International audience; In this paper, an electrical energy management strategy to control the power flow in a battery/supercapacitor hybrid system is presented. The implemented approach relies on the dynamics response of the sources to share the required power. The concept of the system relies on isolated resonant converters. A primary phase-shifted LLC resonant converter is used to connect the batteries bank to the DC-link, while the supercapacitors bank is coupled to the DC-link through a bidirectional CLLC resonant converter controlled by variable frequency control. Performances of the proposed architecture and control method are validated through some simulations. It is shown that the proposed converters can achieve soft switching for all load conditions. That the efficacy and the power density of the system are enhanced. The simulation results validates also the proposed energy management strategy.

This paper presents utilization of the Energetic Macroscopic Representation (EMR) which is a graphical formalism tool to analyze the behavior of a wind energy conversion (WEC) system based on a permanent magnet synchronous generator (PMSG). The aims of this paper are showing the clarity of this tool in the representation of complicated energy systems and the effectiveness of the control strategy deduced from this representation. More precisely, this paper starts from a synoptic with a simple knowledge of a wind energy conversion system to deduce a diagram for the control law based on the action and reaction principle. The methodology of this tool is described in details and the simulation results obtained in MATLAB environment are presented.

This paper presents the new model of LiFePO4- battery dedicated to multi-source systems such as the transport applications or that of the renewables energies. Generally, an application needs a specific model of the battery which takes in to account the real constraints of the using such as the battery State Of Charge, the number of charge/discharge cycle, the DC- current magnitude and its frequency. These physical constraints affect the electric parameters of a lithium-battery. In others terms, the presented physical constraints in above reduce the battery capacitance and they increase the internal resistances.The paper contribution is focused on the proposed model of the LiFePO4-battery with a new method for electric parameters extraction. The specificity of this model is due to the parameters of the parallel circuits that are function of the battery’s open circuit voltage which depends on the state of charge of the battery and the series resistance according to the DC-current ripples frequency. The proposed model of the lithium iron phosphate include two different time constants which are constant during all operations. To do the battery characterization and modeling, the experimental tests based on the battery charge/discharge operations with the fluctuating DC-current are done. From experimental data of the battery, the equivalent- electric circuit parameters are computed. To show the performances of the proposed model, the simulations results are compared to experimental ones obtained with a dynamic current profile.

This paper discusses two control strategies for a small-scale wind energy conversion system developed for micro-grids applications. Whereas control of small-scale Doubly Fed Induction Generator (DFIG)-based wind turbines is not easy to achieve we have developed control strategies for the rotor-side converter, as well as mathematical modeling of the configuration that has been employed. Fixed speed control (direct speed control) and variable speed control (indirect speed control) of the generator rotor are developed, in which a simple maximum power point tracking method was used without taking into account the turbine blade angle. The control approaches are then simulated in MATLAB/Simulink, and the developed models are then used to highlight the behavior of the system. The simulation results are presented and discussed in order to compare the two control strategies especially developed for small-scale wind turbines.

DC-DC resonant converters are increasingly used in renewable energy systems and hybrid electric vehicles because of their high power density and high efficiency. This paper establishes a global study of the most popular topologies of DC-DC resonant converters that is series, parallel, series-parallel, LLC and CLLC resonant converters. First harmonic approximation method (FHA) is used to define the equivalent circuit and to analyse the gain characteristics and limitations of each topology.

Purpose – The purpose of this paper is to propose a new nonlinear control algorithm to control a wind turbine based on permanent magnet synchronous generator (PMSG) connected to the grid via a back-to-back converter. The control algorithm is composed of a flatness-based method for the machine side convertor (MSC) and a voltage-oriented method for the grid side converter (GSC). Design/methodology/approach – For the MSC control, the output variable is chosen properly to prove that the system is flat at first. Then, the appropriate reference trajectories are planned on its components. The reference trajectories are such designed that the system operates in maximum power point tracking (MPPT) mode. Finally, state feedback regulators are used to force the system output to follow its reference. To control the GSC, a classical voltage-oriented control method is used. Findings – The simulation results obtained with a random wind speed are presented in order to prove the validity of the proposed control algorithm. These results show that the system is controlled successfully while it operates in the MPPT mode or in its maximum power limitation mode. Originality/value – In this paper, a new algorithm based on flatness property is presented to control a variable speed wind turbine based on a PMSG. The proposed control method allows the system to operate in optimal operating modes.

International audience; In this paper, an improved bidirectional resonant converter for wide battery voltage applications is proposed. The topology has a symmetrical resonant circuit which guarantees an identical behaviour for both energy transfer directions. The proposed converter has the capability to achieve soft switching for both bridges and the ability to operate under wide input/output voltage with narrow switching frequency variation. That increases the efficiency for both energy transfer directions. First harmonic approximation method (FHA) is used to define the equivalent circuit and to analyse the gain characteristics of the converter. Performances of the proposed converter for wide battery voltage application are evaluated through some simulations using Matlab/Simulink software.

International audience; This paper describes an energy management strategy for an electric vehicle (EV). The proposed EV architecture contains a pack of the batteries which presents the energy source and a pack of the supercapacitors (SC) used as power source. The pack of the batteries produces the necessary energy to move forward the vehicle while the pack of the SC produces the lacking power in acceleration and in braking phases. Two DC-DC converters are used to interface the energy sources with the DC-bus. A bidirectional DC-AC converter is used to connect the traction motor to the DC-bus. The proposed control method is focused on the power flow management within the EV depending on electrical behavior of the energy sources. The validity of the proposed control strategy is proofed through some reduced scale simulations tests using the New European Driving Cycle (NEDC).

International audience; In this paper, the control and energy management strategy are proposed for an electric vehicle (EV) application. The hybrid source is composed of Fuel Cell (FC) and Ultracapacitors (UCs). The proposed energy management is used to share the EV energy requirement between the hybrid energy source, where the UCs are connected to DC-bus through a bidirectional DC/DC converter, and the FC is linked to the DC-bus through unidirectional DC/DC converter. The main purpose of this paper is focused on EV requested power sharing in real time operations between the FC stack and the UCs according to the electrical characteristics of these sources using polynomial correctors. In this study, only the traction operation mode is considered. The validity of the control is proofed through reduced scale experimental tests.

This paper proposes an effective control strategy to enhance the Low Voltage Ride-Through (LVRT) capability of an offshore wind turbine connected to the grid. A new nonlinear control method based on differential flatness property of systems is applied to control the wind turbines in where, the system control is carried out by planning the appropriate trajectories on components of the output variables vector of the system. Also, the reactive power of variable speed wind turbine is managed in this work in order to respect the grid code requirements during voltage dips as well as to reduce their impacts on the grid. Simulation of the system model is carried out in Matlab/SimPowerSystems. The simulation results are presented to demonstrate the effectiveness and robustness of the Flatness-Based Control (FBC) to enhance LVRT of the offshore wind turbine.

This paper proposes an effective control strategy to enhance the Primary Frequency Control (PFC) capability of an offshore wind farm connected to the grid. A new nonlinear control method based on differential flatness properties of systems is applied to control the wind turbines in where, the control system is done by planning the appropriate trajectories on components of the output variables vector of the system. The PFC is assured by use of the energy reserve margins of the Wind Turbine Generators (WTGs). By starting from an imposed droop by the Transmission System Operator (TSO), news trajectories for the output variables of the system are generated and applied to the system control. Consequently, it allows the offshore wind farm to provide relief for the grid during depressed frequency conditions. Advantages of the proposed control method are in the one part, the simplicity of the system control strategy and in the other part, control and smoothing power of the wind farm during the transient state.

This paper presents an analytical solution for prediction of the armature reaction magnetic field in slotted surface mounted permanent magnet radial flux synchronous machines. This technique is used in the case of internal and external rotor radial-field machines. The magnetic field expressions are developed in both slots regions and magnetic airgap region leading to an exact calculation of the effects of slotting on the airgap magnetic quantities. Results from this analytical model are compared to corresponding finite element analyses. This analytical model is then used to estimate the self and mutual inductances.

This paper proposes an improved control strategy for a three phase, four leg inverter used for the simultaneous supply of three phase and single phase AC loads in a transformerless hybrid power system (HPS) application. First, the mathematical model of the inverter is obtained by using the average technique, which allows converter systems to be rapidly and accurately simulated. Then, two control strategies are described. The first one uses the conventional dq0 frame rotating with the angular frequency ω (ω = 314 rad/s) and PI (proportional integral) controllers to ensure voltage and current regulation. The second one is an improved control strategy based on the decomposition of the supply three phase voltage and current into instantaneous positive, negative and homopolar sequence components using phasor representation. These three sequences are controlled independently in their own reference frames as DC signals. The positive sequence is regulated by the PI controllers in a positive reference frame, which rotates counterclockwise, while the negative sequence is regulated by the PI controllers in a negative reference frame, which rotates clockwise at the same angular frequency. Since the proposed strategy uses phasor representation, the actually superposed phasors of the homopolar sequence are spatially displaced at 120°. Then, using a negative reference frame system, the obtained DC signals are regulated by the PI controllers. Simulation results show the validity of the innovative control strategy.

In this paper, the Rainflow Cycles Counting Method is applied to estimate the supercapacitors lifetime. Several studies can be found in the literature but in most of them, estimation methods of supercapacitors lifetime are based only on the Ac-Impedance Spectroscopy Method or on the Cyclic voltammetry. The using of these methods is very fastidious and need a very high number of experimental cycling tests. Sometimes, it can be interesting to have a simplest but accurate method to estimate the life cycles of the supercapacitor. So, abacus can be realized by manufacturer to guide users or to be used in the Supercapacitor Energy Management System (SEMS) simulations. In this paper, a strategy, based on the Rainflow Cycle Counting Method, is established from long term experimental tests. This can facilitate an online estimation of the supercapacitor lifetime and storage energy management.

International audience; This paper presents energy management improvement for a Hybrid Electric Boat (HEB) using frequency approach. Diesel generator is assisted by supercapacitors and lithium-battery to satisfy energetic demand of hybrid electric boat. Supercapacitors and lithium-battery are linked to DC-bus through two bidirectional converters, and diesel generator is connected to DC-bus using three phase controlled rectifier. DC/AC converters connected to two electric motors are used as thrusters system which enables to emulate energetic demand of Hybrid Electric Boat (HEB) in propulsion operations. The power requirement of thrusters is added to embedded appliances demand to obtain load's profile. The contribution of this paper is focused on load's profile sharing between Diesel generator, supercapacitors and lithium-battery according to the dynamic responses of these sources. Proposed method performances are evaluated through some simulations using MATALB/Simulink software.

The main goal of this work is to develop specific procedures for implementation in wind turbine simulators designed especially for small machines. Using blade element methodology, we establish procedures for the torque and power characteristics of a small wind turbine, where some physical construction parameters are known. The algorithm is developed for two simulation procedures, which differ by the parameter used for the set of characteristics (wind speed or pitch angle).

A stochastic ellipsoid modelling of repeatability is proposed for industrial manipulator robots. The covariance matrix of angular position is determined introducing the jump process, which reveals to be a first and second order stationary Gaussian process.From this accurate covariance matrix, the stochastic ellipsoid theory gives the density of position in the workspace around the mean position. Hence the pose repeatability index can be computed in different locations. Computed and experimental repeatability are compared. Experimental repeatability variability is studied. A new “intrinsic repeatability index” is proposed. In conclusion, the modelling reflects well the location and load influence on the repeatability.

A quasi-three-dimensional (3-D) analytical model of the magnetic field in an axial flux permanent-magnet synchronous machine is presented. This model is derived from an exact two-dimensional analytical solution of the magnetic field extended to the 3-D case by a simple and effective radial dependence modeling of the magnetic field. The obtained quasi-3-D solution allows rapid parametric studies of the air-gap magnetic field. Then, analytical modeling of the cogging torque is presented. It is based on the obtained quasi-3-D analytical solution. Results issued from the proposed model in the air gap are compared with those stemming from a 3-D finite-element method simulation as well as with prototype measured values.

La presentation de l'etat de l'art 1 des travaux menes dans le cadre du GdR ME 2 MS sur la modelisation et le diagnostic des defauts de la machine asynchrone a cage, forme l'objectif principal de cet article. Nous y exposons les principales methodes de modelisation fine de la machine asynchrone a cage defectueuse comme le modele de Park etendu, la methode des circuits electriques magnetiquement couples, la methode des reseaux de permeances ainsi que la methode des elements finis. Du point de vue des methodes de diagnostic proprement dites, nous passerons en revue celles basees sur l'analyse spectrale du courant de phase statorique, celles basees sur l'estimation parametrique ainsi que celles mettant en oeuvre des techniques heuristiques telles que la reconnaissance des formes, la logique floue et les reseaux neuronaux. Ces differentes methodes de diagnostic et de modelisation fine pour le diagnostic sont illustrees dans le cas d'un defaut de rupture de barres et d'un defaut de court-circuit interspires dans les bobinages statoriques.

The injection of wind farm production into a grid, needs optimal strategies for energy transfer management. Usually, the power produced by the wind farms does not fulfil all the grid code requirements. The main problem is generally based on the way to reduce the impacts of power production fluctuations on the grid voltage and its frequency. To solve this problem, some authors suggest the use of an interface such as energy storage devices in order to compensate the wind power fluctuations. In fact, the storage devices installed between the wind farm and the grid can improve the power quality in terms of stability but in other hand the size and the cost of the system can be increased. In this paper, two solutions have been proposed in case the power quality produced by the wind farm is out of the grid code requirements. The improvement of the energy quality of an offshore wind farm without storage and connected to the grid is discussed. The proposed solution is to operate the wind turbines with a reserve of power. To distribute this reserve equitably among wind turbines, a proportional distribution algorithms has been developed. The results obtained show clearly the effectiveness of the strategy.

Common-mode voltage (Vcm) generated by voltage inverters is observed on motor windings. This voltage may induce bearing currents, which can eventually damage AC motors and cause larger common-mode currents. Many methods are proposed to eliminate or reduce the common-mode voltage. Most of these methods reduce the DC-bus voltage utilization and increase the output voltage harmonics. This paper introduces a new Active Common-Mode Elimination (ACME) modulation for three-Level Neutral Point Clamped (3L-NPC) inverters. This method is based on a Modified Space Vector Modulation (MSVM) method and a power circuit system located between the inverter and the induction motor. MSVM eliminates the redundant switching states that produce high Vcm levels. Then, the power circuit system eliminates entirely the Vcm. Simulation results show the effectiveness of the proposed method. This method can increase the utilization rate of the DC bus voltage and to reduce voltage harmonics.

In this paper, an intelligent control strategy based on combination of the "flatness based control technique" and the "perturbation and observation (P&O) MPPT algorithm" is developed and investigated to control a hybrid electric energy source (HEPS). This EHPS is composed of a fuel cell system (FC) and a solar panel (SP), as the main source and a supercapacitor bank (SC), as the auxiliary sources. The main property of this strategy is that the system power flow is managed in different operating modes with the same control algorithm (without algorithm commutation). The power flows between the fuel cell, the SC is controlled by the flatness based control technique while a P&O MPPT technique is developed to control power of the SP. To validate performance of the proposed control of the HEPS, the simulation results are presented.

International audience; This paper describes the modeling and control of Permanent Magnet Synchronous Generator (PMSG) of 5MW for wind farms applications. The generators are linked to the grid by means of a fully controlled frequency converter, which consists of two three phase rectifiers, an intermediate DC-bus, and an inverter. The full system is connected to AC grid with phase to phase RMS voltage of 20kV. Proposed control strategies include the Maximum Power Point Tracking (MPPT) for the PMSG speed control, the active/reactive power control, and the DC-bus voltage management. To show the performances of the control strategies, some simulation results are presented and analyzed using Matlab/Simulink software.

In this paper, a new nonlinear control method based on differential flatness is applied to a high-power wind energy conversion system connected to the grid. The control system is done by planning the appropriate trajectories on components of the output variable vector of the system. The main advantage of the proposed method is control of the system even during the transient state as well as the high performance. The studied system includes a three-bladed horizontal wind turbine and a permanent magnet synchronous generator (PMSG) which is connected to the grid through a back to back converter and a filter. In order to study performance of the control strategy, a random profile of the wind speed has been used. The simulation results obtained in Matlab/Simulink environment are presented to validate efficiency of the control strategy.

This paper deals with an electromagnetic device optimization for a new de-stacking process of aluminum sheets. In a first step, we present the principle for generation of the adequate field strength by an electromagnetic separator device. In a second step, we use a simple and efficient method to calculate the three-dimensional (3D) electromagnetic field and we propose a pattern of current density distribution in an aluminum sheet. Finally, this modeling process leads to the calculation of the de-stacking strength and in so doing to the optimum design for an electromagnetic separator device.

This paper deals with errors inherent in modelling wind turbine simulators. Firstly, different wind turbine simulators are categorised. The work concerns simulators having a real-time soft simulator and an electromechanical tracking system, using any type of servomotor 15–17. Having presented the wind turbine linearised models, with respect to types of servomotor control (in speed or in torque), an analysis is made of simulator mathematical models and simulation performance evaluation, according to the dynamical behaviour of the electromechanical tracking systems. Next, the simulator performances calculation is presented, followed by a simulation error analysis for some particular cases, in order to highlight the differences between the speed and torque control structures. Finally, a servomotor choice principle is established, illustrated by numerical results obtained with the servomotor of a real time wind turbine simulator.

This paper presents the control strategy of a wind turbine based on a Permanent Magnet Synchronous Generator (PMSG). The final objective is to conceive a wind-tidal hybrid real time emulator. In the first part, the hardware in the loop simulator (HIL Simulator) is presented. The second section is dedicated to explain the structure of wind-tidal coupling adopted in our approach. Finally the modeling of the wind turbine system and the control strategy are presented. Matlab / Simulink software is used to modeling the system in order to analyze the performances of the control strategy.

The purpose of this paper is to present a real time wind simulator and it's different uses. Given the fact that the simulator is based on a doubly fed induction generator, one of the uses can be the study of different aspects of grid connection and impacts of different faults that may occur in normal operation of wind systems. The studied system is a variable speed wind turbine system with a Doubly Fed Induction Generator (DFIG). The stator of the generator is directly connected to the grid while the rotor is connected through a back-to-back converter which is dimensioned to stand only for a fraction of the generator rated power. The simulator is developed using Hardware-in the-Loop techniques and in order to provide the static and dynamic characteristics of a wind turbine system. We analyzed and developed an experimental system consisting of two main parts: a real time software simulator and an electromechanical system. The Electromechanical System is composed from three electrical drives: an asynchronous machine that emulates the wind turbine, an asynchronous generator, used to study the energy conversion and grid connection problems. The Software simulator is a supervising and control subsystem and is composed from a computational unit and different interface devices. This subsystem is designed equally to study the capability of the classical network to support wind turbine penetration and grid faults impacts. Experimental results from the simulator are presented in order to compare different simulation procedures.

This paper presents a modular photovoltaic power system designed for large-scale power plants integrated into the grid medium voltage. The Maximum Power Point Tracker (MPPT) box using the constant voltage algorithm is embedded in the inverter control system. To avoid the utilization of a DC-DC boost converter, the use of modules' strings with high level of voltage (around 1000 V) has been applied for efficient power transfer in accordance with the inverter phase to phase output voltage (400 V) in the case of 500 kWp photovoltaic system. Furthermore, the DC-link voltage is maintained at a constant value using a Matlab script. A photovoltaic power plant of 20 MWp has been designed, and simulations made by using Simpower System Tool box of Matlab/Simulink. The system shows control ability and an accurate response in terms of maximum power point, unitary power factor and complex power exchanged.

This paper shows that the optimization of the electrical energy production from a tidal turbine is dependent on the constraints of the site. The Raz Blanchard area is presented as an example. The proposed turbine is based on the 0.55MW Doubly Feed Induction Generator (DFIG) connected to a turbine with a radius of 10m. The proposed model is implemented in Matlab/Simulink software for system simulations. The simulations are done using the tidal current magnitude calculated with a hydrodynamic model. The obtained results are presented and analyzed.

International audience; This paper presents the control strategies of an offshore wind energy system based on 5MW Doubly Fed Induction Generator (DFIG). The DFIG seems to be interesting for such high power wind generator systems. The proposed control strategies include the Maximum Power Tracking (MPPT) for the DFIG speed control, the active/reactive power control, and the DC-bus voltage control method. To show the performances of the control strategies, some simulation results are presented and analyzed using Matlab/Simulink software.

The present study attempts to model and simulate the power system of Sonabel, Burkina National Electricity Company under the flexible environment of Simpower System Tool box of Matlab/Simulink. The Burkina high-voltage transmission networks as well as its generation capacities are highlighted. Afterwards, the model has been validated by comparison simulation results with real grid data provided by Sonabel.