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Chen, Wenjun. "Comparison of doubly-fed induction generator and brushless doubly-fed reluctance generator for wind energy applications." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2595.
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The Doubly-fed Induction Generator (DFIG) is the dominant technology for variable-speed wind power generation due in part to its cost-effective partially-rated power converter. However, the maintenance requirements and potential failure of brushes and slip rings is a significant disadvantage of DFIG. This has led to increased interest in brushless doubly-fed generators. In this thesis a Brushless Doubly-Fed Reluctance Generator (BDFRG) is compared with DFIG from a control performance point of view. To compare the performance of the two generators a flexible 7.5kW test facility has been constructed. Initially, a classical cascade vector controller is applied to both generators. This controller is based on the stator voltage field orientation method with an inner rotor (secondary stator) current control loop and an outer active and reactive power control loop. The dynamic and steady state performance of two generators are examined experimentally. The results confirm that the BDFRG has a slower dynamic response when compared to the DFIG due to the larger and variable inductance. Finally a sensorless Direct Power Control (DPC) scheme is applied to both the DFIG and BDFRG. The performance of this scheme is demonstrated with both simulation and experimental results.
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Edwards, Gregory W. "Wind turbine power generation emulation via doubly fed induction generator control." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FEdwards.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2009.<br>Thesis Advisor(s): Julian, Alexander L. Second Reader: Cristi, Roberto. "December 2009." Description based on title screen as viewed on January 28, 2010. Author(s) subject terms: Double Fed Induction Generator (DFIG), Space Vector Modulation (SVM), wind turbine, Field Programmable Gate Array (FPGA), bi-directional power flow. Includes bibliographical references (p. 75). Also available in print.
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Vu, Hoang Giang. "Estimation and diagnostic of doubly-fed asynchronous wind generator." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10151.
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Dans ce mémoire de thèse nous présentons une méthodologie pour le diagnostic et la surveillance en ligne des éoliennes de l'état de l'ensemble machine électrique onduleur à partir de la mesure du champ magnétique continu. Ce travail est scindé en deux parties complémentaires. Dans la première partie, nous donnons quelques contributions concernant l'estimation de l'état et des paramètres pour certaines classes de systèmes non linéaires. Ces mêmes estimateurs ont été validés en simulation et sur un banc d'essai. La deuxième partie porte sur la mise en œuvre et la conception de deux bancs d'essai utilisés pour l'étude des défauts dans un système double alimentation MADA et un ensemble moteur électrique onduleur classique pour l'analyse des défauts du convertisseur. L'identification des paramètres et la technique de contrôle du système en boucle fermé est introduite pour l'application MADA. De plus, les capteurs virtuels sont conçus pour estimer la vitesse mécanique qui est utilisée pour calculer les fréquences caractéristiques défectueuses, et le signal de couple mécanique qui exerce une influence sur l'amplitude de certaines des signatures défectueux typiquement. Finalement, sur la base de la mise en équation théorique des signaux électriques avec défauts puis des simulations correspondantes, une comparaison avec l'expérimentation est réalisée pour valider la technique proposée. Ces travaux montrent l'avantage d'une telle technique dans la simplicité de l'instrumentation mis en œuvre<br>This doctoral thesis presents a methodology for the online condition monitoring of the electrical power drive in wind energy systems based on the local measurement of the DC-bus magnetic field. The work is divided into two complementary parts. In the first part, some contributions related to the estimation of the state and parameters for certain classes of nonlinear systems are provided. The estimators have been validated in simulation and on test benches. The second part focuses on the implementation and control design of two benchmarks used to study defects in a doubly-fed induction generator (DFIG) system and an induction motor power drive. In the former benchmark, the parameters identification of the induction machine and the controller design of the DFIG system are carried out. For the latter test bench, the notable work is to build an induction machine drive for the purpose of fault investigation, in which a PWM generator is developed to control and create the fault of the converter. Furthermore, virtual sensors are designed to estimate mechanical speed that is used to calculate the characteristic frequencies, and mechanical torque signal that has influence on the amplitude of some typical fault signatures. Finally, based on the theoretical aspect of the selected faults, the relevant simulations are developed and experiments are implemented on the benchmarks in order to validate the proposed technique. It has been shown that the diagnostic relying on the magnetic field measurement is feasible and offers various advantages such as simplicity and cost-effectiveness
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Oraee, Ashknaz. "Optimal design of the brushless doubly-fed induction generator." Thesis, University of Cambridge, 2016. https://www.repository.cam.ac.uk/handle/1810/283976.
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Thomas, Andrew J. (Andrew Joseph) 1981. "A doubly-fed permanent magnet generator for wind turbines." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/18013.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.<br>Includes bibliographical references (p. 77-78).<br>Optimum extraction of energy from a wind turbine requires that turbine speed vary with wind speed. Existing solutions to produce constant-frequency electrical output under windspeed variations are undesirable due to complexity, cost, inefficiency or reliability issues. We propose a novel variation of a doubly-fed induction generator which aims to improve power density and simplify construction. Our design is a doubly-fed, dual-rotor, axial-flux, permanent-magnet machine. Progress in the construction of a prototype is described. Analysis of the steady state and dynamic behavior of the machine is detailed, and a control algorithm developed therefrom.<br>by Andrew Joseph Thomas.<br>M.Eng.
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Djurovich, Sinisha. "Analysis of doubly-fed induction generator under electrical fault conditions." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556617.
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This thesis investigates the effects of winding faults on the doubly fed induction generator (DFIG) operation. A DFIG is a wound rotor induction machine that is most commonly used in present day wind power applications. In combination with a back-toback converter in the rotor circuit the DFIG is capable of generating power at constant frequency while operating at variable speed. The aim of the research in this thesis is to develop analytical and experimental tools that would enable the work on establishing of DFIG condition monitoring techniques. DFIG winding faults are examined using the machine current signature analysis (MCSA) method. This method is based on exploring the machine current frequency spectra, and defining and monitoring the fault specific changes in the spectra harmonic content. For this purpose a detailed analytical machine model is developed in this work. The model is capable of representing the effects that various winding faults have on the current spectra and is based on the generalized harmonic analysis. Higher order m.m.f. ~ ·harmonics are taken into account in the model calculations. Combining the model with a connection matrix enables the machine current frequency analysis for various healthy and faulty DFIG winding configurations. The model equations are solved in a time stepping algorithm based on Euler's method. For the purpose of experimental work a DFIG laboratory test rig was built. The test rig is designed to enable the simulation of various DFIG operating regimes and winding faults. The test machine stator winding terminals are taken out to a specially constructed terminal box, where by simple reconnecting of the terminals different winding configurations are achieved. The effect that open-circuit and short-circuit faults have on the DFIG current spectra harmonic content, when compared to healthy operating conditions, was analyzed in both the analytical model and on the test rig. The comparison of the model results against the experimental results shows that they are in very good agreement, thus verifying that the developed model is capable of predicting the real life operating conditions that are present in the simulated system. Some fault specific harmonic components are defined from model predictions and corresponding test rig experiments for each of the winding fault scenarios and DFIG operating conditions analyzed. !tis shown that the frequency of the fault specific harmonic components is dependant on the DFIG operating speed.
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Lei, Ting. "Doubly-fed induction generator wind turbine modelling, control and reliability." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/doublyfed-induction-generator-wind-turbine-modelling-control-and-reliability(2ceb051a-a6fb-43e6-be40-a5023dae4bea).html.
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The trend of future wind farms moving further offshore requires much higher reliability for each wind turbine in order to reduce maintenance cost. The drive-train system and power electronic converter system have been identified as critical sub-assemblies that are subject to higher failure rates than the other sub-assemblies in a wind turbine. Modern condition monitoring techniques may help schedule the maintenance and reduce downtime. However, when it comes to offshore wind turbines, it is more crucial to reduce the failure rates (or reduce the stresses) for the wind turbines during operation since the harsh weather and a frequently inaccessible environment will dramatically reduce their availability once a failure happens. This research examines the mechanical, electrical and thermal stresses in the sub-assemblies of a doubly-fed induction generator (DFIG) wind turbine and how to reduce them by improved control strategies. The DFIG control system (the rotor-side and the grid-side converter control) as well as the wind turbine control system are well established. The interactions of these control systems have been investigated. This research examines several further strategies to reduce the mechanical and electrical stresses. The control system's coordination with the protection schemes (crowbar and dc-chopper) during a grid fault is presented as well. An electro-thermal model of the power converter has been developed to integrate with the DFIG wind turbine model, for the evaluation of the thermal stresses under different operating states and control schemes. The main contributions of this thesis are twofold. A first contribution is made by providing all the control loops with well-tuned controllers in a more integrated methodology. The dynamics of these controllers are determined from their mathematical models to minimize the interference between different control-loops and also to reduce the electrical transients. This thesis proposes a coordination strategy for the damping control, pitch control and crowbar protection which significantly reduces the mechanical oscillations. On the other hand, an integrated model of the wind turbine and converter electro-thermal system is established that can illustrate the performance integration with different control strategies.
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Hamon, Camille. "Doubly-fed Induction Generator Modeling and Control in DigSilent Power Factory." Thesis, KTH, Elektriska energisystem, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119575.
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International agreements have set high demands on the share of renewable energy in the total energy mix. From the different renewable sources, significant investments are made in wind power. More and more wind turbines are being built and their number is due to rise dramatically. There are many different generator technologies, but this paper focuses on the doubly-fed induction generator (DFIG). DFIGs are generators which are connected to the grid on both stator and rotor sides. The machine is controlled via converters connected between the rotor and the grid. The size of these converters determines the speed range of the DFIG. Wind farm connections to the grid must satisfy grid requirements set by transmission system operators. This means that the study of their dynamic responses to disturbances has become a critical issue, and is becoming increasingly important for induction generators, due to their growing size and number. Several computer programs exist to carry out dynamical simulations and this work will focus on one of them, namely Power Factory from DigSilent. It offers a large choice of builtin components. These components can be controlled through input signals. It is therefore possible for the user to design control strategies. Power Factory has two models of DFIG. A new model has also been developed, based upon a controllable voltage source. These three models are compared, in terms of dynamical behavior and simulation time. One is then used to study the effect of introducing a certain signal to the control strategy.
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Hu, Zhouxing. "Development of laboratory doubly fed induction generator for wind energy research." Thesis, Wichita State University, 2010. http://hdl.handle.net/10057/3310.
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This thesis studies the basic concept of doubly-fed induction generators (DFIG) and develops a laboratory model to simulate DFIG wind turbine generators (WTG). “Doubly-fed” refers to the three-phase stator and rotor windings, both of which have electric power exchange with the ac power system. Different from synchronous generators installed in coal, oil, gas, hydro, and nuclear power plants, asynchronous DFIG generators are widely used for wind energy conversion because of the diversity of wind power.
Through the control of back-to-back PWM converters connected between the DFIG rotor and power system, a DFIG can operate at variable speed but constant stator frequency. Below rated wind speed, the DFIG controls the torque on the turbine shaft to track the best operating point (i.e. at best tip-speed ratio). Above rated wind speed, the pitch angle of the turbine blades is adjusted to limit the power captured from the wind. DFIG can provide power factor regulation by controlling the reactive power exchange with the grid.
In this laboratory DFIG experiment, a DC motor is open-loop controlled as a prime mover with variable mechanical power output. A wound-rotor induction motor is mechanically coupled to the DC motor and operated as a DFIG. An IGBT inverter is connected to a variable DC voltage source in order to provide a controllable three-phase voltage applied to the rotor windings. The reactive power output is controlled by setting the magnitude of the rotor excitation voltage. The active power (torque), reactive power output and speed can be controlled by setting the frequency of the rotor excitation voltage. Through manually adjusting the DC input and rotor excitation voltage, the laboratory DFIG is able to operate at a variable simulated wind speed (4 – 25 m/s) with desired power output following the GE 1.5 MW WTG. As an advanced control strategy, decoupled d-q vector control for DFIG using back-to-back converters is studied. Under a stator-flux oriented reference frame, for the rotor-side converter, the rotor d- component (i.e. vrd, ird) controls the stator reactive power (rotor excitation current), while the rotor q- component (i.e. vrq, irq) controls the stator active power (electrical torque); for the supply-side converter, the d- component (i.e. vd, id) controls the DC-link voltage, while the q- component (i.e. vq, iq) controls the reactive power.<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science.
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Zelaya, de la Parra H. "Microprocessor-controlled cycloconverter for excitation of a doubly-fed induction generator." Thesis, University of Bradford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376697.
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Subramanian, Chandrasekaran <1983>. "Grid Connected Doubly Fed Induction Generator Based Wind Turbine under LVRT." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6243/1/Grid_Connected_Doubly_Fed_Induction_Generator_Based_Wind_Turbine_under_LVRT.pdf.
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This project concentrates on the Low Voltage Ride Through (LVRT) capability of Doubly Fed Induction Generator (DFIG) wind turbine. The main attention in the project is, therefore, drawn to the control of the DFIG wind turbine and of its power converter and to the ability to protect itself without disconnection during grid faults. It provides also an overview on the interaction between variable speed DFIG wind turbines and the power system subjected to disturbances, such as short circuit faults. The dynamic model of DFIG wind turbine includes models for both mechanical components as well as for all electrical components, controllers and for the protection device of DFIG necessary during grid faults. The viewpoint of this project is to carry out different simulations to provide insight and understanding of the grid fault impact on both DFIG wind turbines and on the power system itself. The dynamic behavior of DFIG wind turbines during grid faults is simulated and assessed by using a transmission power system generic model developed and delivered by Transmission System Operator in the power system simulation toolbox Digsilent, Matlab/Simulink and PLECS.
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Subramanian, Chandrasekaran <1983>. "Grid Connected Doubly Fed Induction Generator Based Wind Turbine under LVRT." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6243/.
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This project concentrates on the Low Voltage Ride Through (LVRT) capability of Doubly Fed Induction Generator (DFIG) wind turbine. The main attention in the project is, therefore, drawn to the control of the DFIG wind turbine and of its power converter and to the ability to protect itself without disconnection during grid faults. It provides also an overview on the interaction between variable speed DFIG wind turbines and the power system subjected to disturbances, such as short circuit faults. The dynamic model of DFIG wind turbine includes models for both mechanical components as well as for all electrical components, controllers and for the protection device of DFIG necessary during grid faults. The viewpoint of this project is to carry out different simulations to provide insight and understanding of the grid fault impact on both DFIG wind turbines and on the power system itself. The dynamic behavior of DFIG wind turbines during grid faults is simulated and assessed by using a transmission power system generic model developed and delivered by Transmission System Operator in the power system simulation toolbox Digsilent, Matlab/Simulink and PLECS.
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Broekhof, Alexander. "Controlling the brushless doubly-fed induction generator (BDFIG) in wind turbine applications." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/283961.
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Lu, Bin Ph D. Massachusetts Institute of Technology. "Experimental verification for the design of a doubly-fed permanent magnetic generator." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42060.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Includes bibliographical references (p. 111-112).<br>This is a continuous work on the project of a doubly-fed permanent magnet (DFPM) generator for wind turbines. The construction of a prototype machine was finally finished and experiments were conducted to verify the design of the DFPM machine and to establish a basis for designing more powerful machines in industry usage. In the thesis, a finite element model of the machine is established, from which the parameters of the prototype machine are estimated. Then the experiment data are compared with the estimated values to verify the model of the machine. At last a vector control method is proposed with the stability analysis using the parameters developed from the model. Moreover, the damping effect of the permanent magnet (PM) rotor plate is explored. Keywords: doubly-fed induction, permanent magnet, finite element, open circuit, v-curve, damping coil, vector control, sensorless.<br>by Bin Lu.<br>S.M.
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Wyllie, Peter Bruce. "Electrothermal modelling for doubly fed induction generator converter reliability in wind power." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10902/.
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Increased reliance upon renewable energy sources, chiefly wind, places a growing emphasis on the reliability of the technology used in Wind Turbines. The current Wind Turbine fleet is dominated by the Doubly Fed Induction Machine WT, which utilises a partially rated power electronic converter to vary the speed of the rotor and thus ensure the maximum energy capture available from the wind. This converter is associated with a significant percentage of WT failures. This thesis examines the low frequency temperature cycling occurring in one half of the back to back converter which results in a high failure rate of the rotor side converter as compared to the grid side converter. To this end a MATLAB/PLECS model was constructed to demonstrate the temperature cycling occurring in a 2.5MW DFIG WT. Lifetime of the semiconductor devices was extrapolated. An adaptation to the standard Maximum Power Point Tracking control method was suggested in which the lowest operating frequencies (less than 2.33Hz) were avoided. In doing so, lifetime was observed to increase at a minor cost to energy yield from the WT.
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Ahmed, Eshita. "Hybrid Renewable Energy System Using Doubly-Fed Induction Generator and Multilevel Inverter." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26501.
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The proposed hybrid system generates AC power by combining solar and wind energy converted by a doubly-fed induction generator (DFIG). The DFIG, driven by a wind turbine, needs rotor excitation so the stator can supply a load or the grid. In a variable-speed wind energy system, the stator voltage and its frequency vary with wind speed, and in order to keep them constant, variable-voltage and variable-frequency rotor excitation is to be provided. A power conversion unit supplies the rotor, drawing power either from AC mains or from a PV panel depending on their availability. It consists of a multilevel inverter which gives lower harmonic distortion in the stator voltage. Maximum power point tracking techniques have been implemented for both wind and solar power. The complete hybrid renewable energy system is implemented in a PSIM-Simulink interface and the wind energy conversion portion is realized in hardware using dSPACE controller board.
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Wang, Lei. "Advanced control of doubly-fed induction generator based variable speed wind turbine." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/10575/.
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This thesis deals with the modeling, control and analysis of doubly fed induction generators (DFIG) based wind turbines (DFIG-WT). The DFIG-WT is one of the mostly employed wind power generation systems (WPGS), due to its merits including variable speed operation for achieving the maximum power conversion, smaller capacity requirement for power electronic devices, and full controllability of active and reactive powers of the DFIG. The dynamic modeling of DFIG-WT has been carried out at first in Chapter 2, with the conventional vector control (VC) strategies for both rotor-side and grid-side converters. The vector control strategy works in a synchronous reference frame, aligned with the stator-flux vector, became very popular for control of the DFIG. Although the conventional VC strategy is simple and reliable, it is not capable of providing a satisfactory transient response for DFIG-WT under grid faults. As the VC is usually designed and optimized based on one operation point, thus the overall energy conversion efficiency cannot be maintained at the optimal point when the WPGS operation point moves away from that designed point due to the time-varying wind power inputs. Compared with VC methods which are designed based on linear model obtained from one operation point, nonlinear control methods can provide consistent optimal performance across the operation envelope rather than at one operation point. To improve the asymptotical regulation provided by the VC, which can't provide satisfactory performance under voltage sags caused by grid faults or load disturbance of the grid, input-output feedback linearization control (IOFLC) has been applied to develop a fully decoupled controller of the active $\&$ reactive powers of the DFIG in Chapter 3. Furthermore, a cascade control strategy is proposed for power regulation of DFIG-WT, which can provide better performance against the varying operation points and grid disturbance. Moreover, to improve the overall energy conversion efficiency of the DFIG-WT, FLC-based maximum power point tracking (MPPT) has been investigated. The main objective of the FLC-based MPPT in Chapter 4 is to design a global optimal controller to deal with the time-varying operation points and nonlinear characteristic of the DFIG-WT. Modal analysis and simulation studies have been used to verify the effectiveness of the FLC-based MPPT, compared with the VC. The system mode trajectory, including the internal zero-dynamic of the FLC-MPPT are carefully examined in the face of varied operation ranges and parameter uncertainties. In a realistic DFIG-WT, the parameter variability, the uncertain and time-varying wind power inputs are existed. To enhance the robustness of the controller, a nonlinear adaptive controller (NAC) via state and perturbation observer for feedback linearizable nonlinear systems is applied for MPPT control of DFIG-WT in Chapter 5. In the design of the controller, a perturbation term is defined to describe the combined effect of the system nonlinearities and uncertainties, and represented by introducing a fictitious state in the state equations. As follows, a state and perturbation observer is designed to estimate the system states and perturbation, leading to an adaptive output-feedback linearizing controller which uses the estimated perturbation to cancel system perturbations and the estimated states to implement a linear output feedback control law for the equivalent linear system. Case studies including with and without wind speed measurement are carried out and proved that the proposed NAC for MPPT of DFIG-WT can provide better robustness performance against the parameter uncertainties. Simulation studies for demonstrating the performance of the proposed control methods in each chapter, are carried out based on MATLAB/SIMULINK.
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Van, Binh Nguyen [Verfasser]. "Control of synchronized doubly-fed induction generator under grid conditions / Nguyen Van Binh." Aachen : Shaker, 2015. http://d-nb.info/1080762493/34.
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Aravinthan, Abhiramy. "Linear quadratic regulator design for doubly fed induction generator using singular perturbation techniques." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5523.
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Doubly fed induction generators (DFIG) are widely used in wind power generation because of their ability to be operated at varying rotational speeds while producing power output at a constant frequency. Electrical dynamics of a DFIG is modeled using field oriented control and represented as fourth order system. This fourth order dynamics exposes a two-time scale behavior. Using singular perturbation techniques the time scales can be separated as slow and fast subsystems. Feedback control schemes can be designed and the closed-loop stability of each model can be compared. In this work, a linear quadratic feedback controller is designed for the DFIG electrical dynamics using exact, reduced order and composite models. The performances of the closed loop models are compared based on the system cost. The robustness and reliability of the control schemes are analyzed for each controller designs based on the nominal system. Based on the analysis and results, the reduced order controller performance is equally as good as the exact and composite designs during steady state operations.<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Abbey, Chad. "A doubly-fed induction generator and energy storage system for wind power applications /." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81522.
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Wind generation has become the most important alternate energy source and has experienced increased growth in Europe during the past decade while more recently, the same trends have been exhibited in North America. Although it has great potential as an alternative to less environmentally friendly energy sources, there are various technical challenges that cause wind to be regarded negatively by many utilities. Others are hesitant to accept its widespread implementation, particularly when the penetration of wind in a given area is high.<br>This work presents the addition of an energy storage system to a wind turbine design.<br>Various advantages are exhibited for the wind turbine with energy storage. Firstly, the generator is capable of accurately controlling the output power of the generator and inevitably of the wind park. Reactive power requirements are also reduced as a result of a more stable voltage at the point of interconnection. In addition, improved transient performance is exhibited for various local disturbances.
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Sam, Mahmodicherati. "Direct Power Control of a Doubly Fed Induction Generator in Wind Power Systems." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1470315542.
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Ozakturk, Meliksah. "Power electronic systems design co-ordination for doubly-fed induction generator wind turbines." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/power-electronic-systems-design-coordination-for-doublyfed-induction-generator-wind-turbines(ebe4de00-07ad-4b06-8b8d-79be291804e7).html.
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Wind turbine modelling using doubly-fed induction generators is a well-known subject. However, studies have tended to focus on optimising the components of the system rather than considering the interaction between the components. This research examines the interaction of the control methods for a doubly-fed induction generator (DFIG) in a wind turbine application integrating them with the crowbar protection control and DC-link brake control to make the best use of the converter. The controls of the rotor-side and the grid-side converters of the DFIG model are both well established and have been shown to work. Typically the crowbar protection is designed in order to protect the rotor-side converter and the power electronic components of the DFIG system from high currents occurring in the rotor due to the faults. The DC-link brake-overvoltage protection is also designed to prevent the overcharging of the DC-link capacitor placed between the rotor-side converter and the grid-side converter. In order to show that these protection schemes work and with thought can co-ordinate with each other, tests consisting of a number of balanced three-, two- and one-phase voltage sags are applied to the network voltage. The main contributions of this thesis are establishing operational tuning and design limits for the controllers and system subassemblies. This is to minimise the electrical subsystem interaction while maintaining adequate performance, and have an improved DC-link control. This work also includes a full electrical system study of the wind turbine and an essential literature review on significant references in the field of the DFIG wind turbine system modelling, control and protection. Specifically this research project makes a number of novel contributions to the literature: enhanced DC voltage control including operating point sensitivity analysis and dynamic stiffness assessment, sensitivity and robustness analyses of the power loop control and control loop segmentation by appropriately tuning the controller loops.
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Mazari, Shukul. "Control design and analysis of doubly-fed induction generator in wind power application." Thesis, [Tuscaloosa, Ala. : University of Alabama Libraries], 2009. http://purl.lib.ua.edu/2183.
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Orfanos-Pepainas, Stamatios. "Adaptive control and parameter identification of a doubly-fed induction generator for wind power." Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5510.
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Approved for public release; distribution is unlimited.<br>The use of Doubly-Fed Induction Generators (DFIG) for wind energy conversion is addressed in this thesis. It is well known that when the stator is connected to the electric grid, the rotor voltage can control both mechanical torque and reactive electric power. To guarantee efficient wind energy conversion, it is important to research and design more advanced control schemes. In this thesis, we first review the basic theory behind DFIGs and Adaptive Control. Next we design an adaptive controller for a wind turbine using a DFIG and model and simulate the system. In order to create a valid assessment on the results of this method, we compare the system's performance with a standard control scheme based on proportional integral (PI) controllers as proposed in standard approaches.
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Pena, Guinez Ruben S. "Vector control strategies for a doubly-fed induction generator driven by a wind turbine." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318644.
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Bensadeq, Asim. "Design and control of the Brushless Doubly Fed Twin Induction Generator (BDFTIG) using dSPACE." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/32875.
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The aim of this research is to present indirect vector control (IVC) for a Brushless Doubly Fed Twin Induction Generator (BDFTIG) for wind energy conversion. The system is anticipated as an advanced solution to the conventional doubly fed induction generator (DFIG) to decrease the maintenance cost and increase the system reliability of the wind turbine system. The proposed BDFTIG employs two cascaded induction machine sets, which consists of two wound rotor induction machines with their rotors connected in cascade to eliminate the brushes and copper rings in the DFIG. This new machine would ideally have one common rotor, and the two stators to be integrated within one housing. For the practical purpose of this research two separate DFIG’s were coupled together to a single prime mover. The dynamic model of the BDFTIG with the two machines’ rotors electromechanically coupled in a back-to-back configuration is developed and implemented using Matlab/Simulink. Based on the model, the control scheme for flexible power flow control in the BDFTIG with a bidirectional converter is developed. Independent control of the active and reactive power flow is achieved by a four-quadrant power converter under the closed-loop stator flux oriented control scheme. In the proposed control strategy, the generator speed tracks the reference speed very well, and thus the maximum power extract. Which is the optimum speed derived from the maximum power point tracking of the wind turbine.
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Shi, Kai. "Advanced control of doubly-fed induction generator based wind turbines for dynamic performance improvement." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3018211/.
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Malik, Naveed ur Rehman. "Modelling, Analysis, and Control Aspects of a Rotating Power Electronic Brushless Doubly-Fed Induction Generator." Doctoral thesis, KTH, Elektrisk energiomvandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174349.
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This thesis deals with the modeling, analysis and control of a novel brushlessgenerator for wind power application. The generator is named as rotatingpower electronic brushless doubly-fed induction machine/generator (RPEBDFIM/G). A great advantage of the RPE-BDFIG is that the slip power recoveryis realized in a brushless manner. This is achieved by introducing an additionalmachine termed as exciter together with the rotating power electronicconverters, which are mounted on the shaft of a DFIG. It is shown that theexciter recovers the slip power in a mechanical manner, and delivers it backto the grid. As a result, slip rings and carbon brushes can be eliminated,increasing the robustness of the system, and reducing the maintenance costsand down-time of the turbine. To begin with, the dynamic model of the RPE-BDFIG is developed andanalyzed. Using the dynamic model, the working principle of the generatoris understood and its operation explained. The analysis is carried out atspeeds, ±20% around the synchronous speed of the generator. Moreover, thedynamics of the generator due to external load-torque disturbances are investigated.Additionally, the steady-state model is also derived and analyzed forthe machine, when operating in motor mode. As a next step, the closed-loop control of the generator is considered indetail. The power and speed control of the two machines of the generator andthe dc-link voltage control is designed using internal model control (IMC)principles. It is found that it is possible to maintain the stability of thegenerator against load-torque disturbances from the turbine and the exciter,at the same time maintain a constant dc-link voltage of the rotor converter.The closed-loop control is also implemented and the operation of the generatorwith the control theory is confirmed through experiments.In the third part of the thesis, the impact of grid faults on the behaviourof the generator is investigated. The operation of the generator and its responseis studied during symmetrical and unsymmetrical faults. An approachto successful ride through of the symmetrical faults is presented, using passiveresistive network (PRN). Moreover, in order to limit the electrical and mechanicaloscillations in the generator during unsymmetrical faults, the dualvector control (DVC) is implemented. It is found that DVC to a certain extentcan be used to safeguard the converter against large oscillations in rotorcurrents. Finally, for completeness of the thesis, a preliminary physical design ofthe rotating power electronic converter has been done in a finite elementsoftware called ANSYS. The thermal footprint and the cooling capability,with estimates of the heatsink and fan sizes, are presented. Besides, another variant of a rotating electronic induction machine whichis based on the Lindmark concept and operating in a single-fed mode is also investigated. It’s steady-state model is developed and verified through experiments.<br><p>QC 20151006</p>
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Pierce, Seth J. "Reducing stator current harmonics for a doubly-fed induction generator connected to a distorted grid." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/37693.
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Approved for public release; distribution is unlimited<br>The Department of Defense (DoD) is increasing its demand for reliable renewable energy sources. The doubly-fed induction generator (DFIG) is widely used to extract electrical energy from wind and is a useful means for the DoD to achieve its renewable energy goals. The DFIG is susceptible to electric grid voltage harmonics, which is a potential obstacle for implementing stable wind-energy systems. Two existing rotor voltage controllers are modeled in this thesis for eventual implementation in a laboratory DFIG wind energy system. The first controller uses multiple proportional-integral (PI) controllers to filter out the fifth and seventh stator current harmonics. Each PI controller operates in a reference frame that rotates in synchronicity with the harmonic that is being filtered. The second controller operates in the synchronous reference frame and simultaneously filters both the fifth and seventh stator current harmonics using a double integrator called a proportional-resonant controller (PR). The PI controller is shown to be more effective at eliminating the stator current than the PR controller but has a slower reaction time. The PR controller requires fewer computations but has more stability concerns. Both controllers reduce torque oscillations resulting from the grid distortion by approximately the same amount.
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Dehnavifard, Hossein. "Development of a scaled doubly-fed induction generator for assessment of wind power integration issues." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/23390.
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Years of experience have been dedicated to the advancement of thermal power plant technology, and in the last decade the investigation has focused on the wind energy conversion system (WECS). Wind energy will play an important role in the future of the energy market, due to the changing climate and the fossil fuel crisis. Initially, wind energy was intended to cover a small portion of the energy market, but in the long term it should compete with conventional fossil fuel power generation. The movement of the power system towards this new phenomena has to be investigated before the wind energy share increases in the network. Therefore, the wind energy integration issues serve as an interesting topic for authors to improve the perception of integration, distribution, variability and power flow issues. Several simulation models have been introduced in order to resolve this issue, however, the variety in types of wind turbines and the network policies result in these models having limited accuracy or being developed for specific issues. The micro-machine is introduced in order to overcome the challenges of simulation models and the costs involved in field tests. In the past, the grid integration issue of large turbo-alternators was solved by the micro-machines. A variety of tests are possible with the micro-machines and they also increase the flexibility of the system. The increased accuracy as well as the ability to carry out real-time analysis and compare actual field test data are strengths worth utilizing. This project involves the designing and the prototyping of a scaled doubly-fed induction generator (micro-DFIG). The machine is also analysed and tested. The scaling of the micro-machine is achieved by means of a dimensional analysis, which is a mathematical method that allows machines and systems to be downscaled by establishing laws of similitude between the reference model and its scaled model. MATLAB/SIMULINK, Maxwell and Solid Work are employed to achieve the objectives of this project.
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Yunus, A. M. Shiddiq. "Application of SMES Unit to improve the performance of doubly fed induction generator based WECS." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/1450.
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Due to the rising demand of energy over several decades, conventional energy resources have been continuously and drastically explored all around the world. As a result, global warming is inevitable due to the massive exhaust of CO2 into the atmosphere from the conventional energy sources. This global issue has become a high concern of industrial countries who are trying to reduce their emission production by increasing the utilization of renewable energies such as wind energy. Wind energy has become very attractive since the revolution of power electronics technology, which can be equipped with wind turbines. Wind energy can be optimally captured with wind turbine converters. However, these converters are very sensitive if connected with the grid as grid disturbances may have a catastrophic impact on the overall performance of the wind turbines.In this thesis, superconducting magnetic energy storage (SMES) is applied on wind energy conversion systems (WECSs) that are equipped with doubly fed induction generators (DFIGs) during the presence of voltage sags and swells in the grid side. Without SMES, certain levels of voltage sags and swells in the grid side may cause a critical operating condition that may require disconnection of WECS to the grid. This condition is mainly determined by the voltage profile at the point of common coupling (PCC), which is set up differently by concerned countries all over the world. This requirement is determined by the transmission system operator (TSO) in conjunction with the concerned government. The determined requirement is known as grid codes or fault ride through (FRT) capability.The selection of a SMES unit in this thesis is based on its advantages over other energy storage technologies. Compared to other energy storage options, the SMES unit is ranked first in terms of highest efficiency, which is 90-99%. The high efficiency of the SMES unit is achieved by its low power loss because electric currents in the coil encounter almost no resistance and there are no moving parts, which means no friction losses. Meanwhile, DFIG is selected because it is the most popular installed WECS over the world. In 2004 about 55% of the total installed WECS worldwide were equipped with DFIG. There are two main strategies that can be applied to meet the grid requirements of a particular TSO. The first strategy is development of new control techniques to fulfil the criterion of the TSOs. This strategy, however, is applicable only to the new WECS that have not been connected to the power grid. If new control techniques are applied to the existing gridconnected WECSs, they will not be cost effective because the obsolete design must be dismantled and re-installed to comply with current grid code requirements. The second strategy is the utilization of flexible AC transmission system (FACTS) devices or storage energy devices to meet the grid code requirements. This strategy seems more appropriate for implementation in the existing WECS-grid connection in order to comply with the current grid code requirements. By appropriate design, the devices might be more cost effective compared to the first strategy, particularly for the large wind farms that are already connected to the grid.A new control algorithm of a SMES unit, which is simple but still involves all the important parameters, is employed in this study. Using the hysteresis current control approach in conjunction with a fuzzy logic controller, the SMES unit successfully and effectively improves the performance of the DFIG during voltage sag and swell events in the grid side; thus, this will prevent the WECS equipped with DFIG from being disconnected from the grid according to the selected fault ride through used in this study. The dynamic study of DFIG with SMES during short load variation is carried out as an additional advantage of SMES application on a DFIG system. In this study, the proposed SMES unit is controlled to compensate the reduced transfer power of DFIG during the short load variation event. Moreover, the SMES unit is also engaged in absorbing/storing some amount of excessive power that might be transferred to the grid when the local loads are suddenly decreased. Finally, the studies of intermittent misfires and fire-through that take place within the converters of DFIG are carried out in order to investigate the impact of these converter faults on the performance of DFIG. In this part, the proposed SMES unit is controlled to effectively improve the DFIG’s performance in order to prevent it from being disconnected or shut down from the power grid during the occurrence of these intermittent switching faults.
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Zafar, Jawwad. "Winding short-circuit fault modelling and detection in doubly-fed induction generator based wind turbine systems." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209854.
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Abstract<p><p>This thesis deals with the operation of and winding short-circuit fault detection in a Doubly-Fed Induction Generator (DFIG) based Wind Turbine Generator System (WTGS). Both the faulted and faultless condition of operation has been studied, where the focus is on the electrical part of the system. The modelled electrical system is first simulated and the developed control system is then validated on a test bench. The test-bench component dimensioning is also discussed.<p><p>The faultless condition deals with the start-up and power production mode of operation. Control design based on the Proportional Integral (PI) control technique has been compared for power and torque control strategies against the Linear Quadratic Gaussian (LQG) control technique, at different operating points through the variable-speed region of WTGS operation following the maximum power curve of the system. It was found that the torque control strategy offered less degradation in performance for both the control techniques at operating points different for the one for which the control system was tuned. The start-up procedure of the DFIG based WTGS has been clarified and simplified. The phase difference between the stator and the grid voltage, which occurs due to the arbitrary rotor position when the rotor current control is activated, is minimized by using a sample-and-hold technique which eliminates the requirement of designing an additional controller. This method has been validated both in simulation and experiments.<p><p>The faulted condition of operation deals with the turn-turn short-circuit fault in the phase winding of the generator. The model of the generator, implemented using the winding-function approach, allows the fault to be created online both in a stator and a rotor phase. It has been demonstrated that the magnitude of the current harmonics, used extensively in literature for the Machine Current Signature Analysis (MCSA) technique for winding short-circuit fault detection, is very different when the location of the fault is changed to another coil within the phase winding. This makes the decision on the threshold selection for alarm generation difficult. Furthermore, the control system attenuates the current harmonics by an order of magnitude. This attenuation property is also demonstrated through experiments. The attention is then shifted to the negative-sequence current component, resulting from the winding unbalance, as a possible fault residual. Its suitability is tested in the presence of noise for scenarios with different fault locations, fault severity in terms of the number of shorted-turns and grid voltage unbalance. It is found that due to the presence of a control system the magnitude of the negative-sequence current, resulting from the fault, remains almost the same for all fault locations and fault severity. Thus, it was deemed more suitable as a fault residual. In order to obtain a fast detection method, the Cumulative Sum (CUSUM) algorithm was used. The test function is compared against a threshold, determined on the basis of expected residual magnitude and the time selected for detection, to generate an alarm. The validation is carried out with noise characteristics different from the ones used during the design and it is shown that the voltage unbalance alone is not able to trigger a false alarm. In all the scenarios considered, the detection was achieved within 40 ms despite the presence of measurement filters.<br>Doctorat en Sciences de l'ingénieur<br>info:eu-repo/semantics/nonPublished
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Zou, Yu. "Modeling, Control and Maximum Power Point Tracking (MPPT) of Doubly-fed Induction Generator (DFIG) Wind Power System." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342445136.
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Konopinski, Ryan. "Voltage security assessment with high penetration levels of utility-scale doubly fed induction generator wind plants." [Ames, Iowa : Iowa State University], 2009.
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Kim, Hyong Sik. "Brushless Doubly-Fed Reluctance Generator under Voltage Dips for Wind Energy Conversion System: Modelling and Simulation." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/12482.
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Under current trends in the wind energy market, the Brushless Doubly-Fed Reluctance Generator (BDFRG) is regarded as one of the generators that could replace the Doubly-Fed Induction Generator (DFIG), which dominates the current wind energy market. In various literature, BDFRG is proposed to possess advantages over DFIG under current trends, such as the use of offshore wind and the stricter grid codes, while possessing the advantages of DFIG. Thus, some aspects of BDFRG have been researched; however, other aspects have not yet been investigated, including its behaviour under voltage dips, which is one of the main grid issues for wind energy conversion systems (WECS). This thesis aims, therefore, to investigate the behaviour of BDFRG under voltage dips using simulations, in order to compare the dynamic behaviours of the two generators, DFIG and BDFRG, in four different cases varying in power ratings (4kW and 2MW) and the magnitude of the voltage dips (50% and 95%) under both symmetrical and unsymmetrical voltage dips. The findings of this study show that BDFRG is superior to DFIG under all cases of voltage dips tested. The reasons for these phenomena are explained in the discussion chapter, which is followed by the conclusion and suggestions for future work.
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Shen, Baike 1972. "Slip frequency phase lock loop (PLL) for decoupled P-Q control of doubly-fed induction generator (DFIG)." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81568.
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The term "sensor-less" in power electronic drives refers to measurement of mechanical shaft position and/or speed from the currents and voltages of the electrical machine. This thesis presents innovative sensor-less means (a Slip Frequency Phase Lock Loop (PLL) and a gamma-delta Axes Aligner) for implementing decoupled P-Q control of a doubly-fed induction generator (DFIG) for wind-turbine application. Proofs of concepts are by digital simulations.<br>The accuracy of the Slip Frequency Phase Lock Loop in speed estimation is evaluated; the origin of a shortcoming (small phase lag) located and compensated for.<br>The Slip Frequency Phase Lock Loop (PLL) and a gamma-delta Axes Aligner are then evaluated as parts of the decoupled P-Q control of a wind turbine driven doubly-ed induction generator. The research succeeds in realizing robust decoupled P-Q control, that is one in which the generator parameters do not have to be known precisely and can have minor variations such as drifts with temperature. The system has been successfully tested for optimal wind power acquisition.
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Sae-Kok, Warachart. "Converter fault diagnosis and post-fault operation of a doubly-fed induction generator for a wind turbine." Thesis, University of Strathclyde, 2008. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21980.
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Wind energy has become one of the most important alternative energy resources because of the global warming crisis. Wind turbines are often erected off-shore because of favourable wind conditions, requiring lower towers than on-shore. The doubly-fed induction generator is one of the most widely used generators with wind turbines. In such a wind turbine the power converters are less robust than the generator and other mechanical parts. If any switch failure occurs in the converters, the wind turbine may be seriously damaged and have to stop. Therefore, converter health monitoring and fault diagnosis are important to improve system reliability. Moreover, to avoid shutting down the wind turbine, converter fault diagnosis may permit a change in control strategy and/or reconfigure the power converters to permit post-fault operation. This research focuses on switch fault diagnosis and post-fault operation for the converters of the doubly-fed induction generator. The effects of an open-switch fault and a short-circuit switch fault are analysed. Several existing open-switch fault diagnosis methods are examined but are found to be unsuitable for the doubly-fed induction generator. The causes of false alarms with these methods are investigated. A proposed diagnosis method, with false alarm suppression, has the fault detection capability equivalent to the best of the existing methods, but improves system reliability. After any open-switch fault is detected, reconfiguration to a four-switch topology is activated to avoid shutting down the system. Short-circuit switch faults are also investigated. Possible methods to deal with this fault are discussed and demonstrated in simulation. Operating the doubly-fed induction generator as a squirrel cage generator with aerodynamic power control of turbine blades is suggested if this fault occurs in the machine-side converter, while constant dc voltage control is suitable for a short-circuit switch fault in the grid-side converter.
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Kareem, Amer Obaid. "Performance analysis of doubly-fed induction generator (DFIG)-based wind turbine with sensored and sensorless vector control." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3539.
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Conventional energy sources are limited and pollute the environment. Therefore more attention has been paid to utilizing renewable energy resources. Wind energy is the fastest growing and most promising renewable energy source due to its economically viability. Wind turbine generator systems (WTGSs) are being widely manufactured and their number is rising dramatically day by day. There are different generator technologies adopted in wind turbine generator systems, but the most promising type of wind turbine for the future market is investigated in the present study, namely the doubly-fed induction generator wind turbine (DFIG). This has distinct advantages, such as cost effectiveness, efficiency, less acoustic noise, and reliability and in addition this machine can operate either in grid-connected or standalone mode. This investigation considers the analysis, modeling, control, rotor position estimation and impact of grid disturbances in DFIG systems in order to optimally extract power from wind and to accurately predict performance. In this study, the dynamic performance evaluation of the DFIG system is depicted the power quantities (active and reactive power) are succeed to track its command signals. This means that the decouple controllers able to regulating the impact of coupling effect in the tracking of command signals that verify the robust of the PI rotor active power even in disturbance condition. One of the main objectives of this study is to investigate the comparative estimation analysis of DFIG-based wind turbines with two types of PI vector control using PWM. The first is indirect sensor vector control and the other type includes two schemes using model reference adaptive system (MRAS) estimators to validate the ability to detect rotor position when the generator is connected to the grid. The results for the DFIG-based on reactive power MRAS (QRMRAS) are compared with those of the rotor current-based MRAS (RCMRAS) and the former scheme proved to be better and less sensitive to parameter deviations, its required few mathematical computations and was more accurate. During the set of tests using MATLAB®/SMULINK® in adjusting the error between the reference and adaptive models, the estimated rotor position can be obtained with the objective of achieving accurate rotor position information, which is usually measured by rotary encoders or resolvers. The use of these encoders will conventionally lead to increased cost, size, weight, and wiring ii complexity and reduced the mechanical robustness and reliability of the overall DFIG drive systems. However the use of rotor position estimation represents a backup function in sensor vector control systems when sensor failure occurs. The behavioral response of the DFIG-based wind turbine system to grid disturbances is analyzed and simulated with the proposed control strategies and protection scheme in order to maintain the connection to the network during grid faults. Moreover, the use of the null active and reactive reference set scheme control strategy, which modifies the vector control in the rotor side converter (RSC) contributes to limiting the over-current in the rotor windings and over-voltage in the DC bus during voltage dips, which can improve the Low Voltage Ride-through (LVRT) ability of the DFIG-based wind turbine system.
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ZHENG, XIANGPENG. "Control method for the wind turbine driven by doubly fed induction generator under the unbalanced operating conditions." Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1367717182.
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Kunzler, Júnior Júlio Vítor. "Análises teórica e experimental do Gerador Assíncrono de Dupla Alimentação - o GEADA, e contribuição à sua operação." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/8686.
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Este trabalho apresenta a análise teórica e experimental do gerador assíncrono de dupla alimentação, denominado GEADA ao longo deste trabalho, operando em regime permanente com velocidade não fixa, mas com freqüência da armadura constante. Compreende o escopo do trabalho a análise teórica a partir do circuito equivalente do gerador, a análise teórica e experimental da curva de magnetização do GEADA operando em freqüência do rotor variável, uma proposta de adaptação da curva de capacidade aplicada na operação dos geradores síncronos para o GEADA e a sua análise considerando-o como máquina síncrona a partir dos seus terminais, os ensaios normalizados e complementares necessários para o levantamento dos parâmetros para este circuito equivalente e ensaios do GEADA operando com carga para verificação de seu desempenho Os resultados obtidos permitem um melhor entendimento desse sistema de geração, de suas condições de operação e utilização em sistemas de geração de velocidade não fixa como, por exemplo, sistemas eólicos e hidrelétricos.<br>The study presents the theoretical and experimental analysis of the double fed asynchronous generator, called GEADA, operating in steady state with non-fixed speed but with constant armature frequency. It comprehends the theoretical analysis based on the equivalent circuit of this generator, the theoretical and experimental analysis of the curve of magnetization of the GEADA operating with variable rotor frequency. A proposal of adaptation of the capability curve applied in the operation of the synchronous generators for the GEADA is also presented, its analysis considering it as a synchronous machine from its terminals, the standard and complementary tests necessary for the calculation of the parameters for the equivalent circuit and the tests with the GEADA operating under on-load conditions to verify its performance. The achieved results allow a better understanding of this generation system, its operational conditions and applicability to the power generation systems based on variable speed, such as wind and hydroelectric power plants.
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Naggar, Ahmed el [Verfasser], and István [Akademischer Betreuer] Erlich. "Advanced modeling and analysis of the doubly-fed induction generator based wind turbines / Ahmed El Naggar ; Betreuer: István Erlich." Duisburg, 2017. http://d-nb.info/1139640623/34.
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Feehally, Thomas. "Electro-mechanical interaction in gas turbine-generator systems for more-electric aircraft." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/electromechanical-interaction-in-gas-turbinegenerator-systems-for-moreelectric-aircraft(64606031-8744-4925-a8e1-3bf4ea108696).html.
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Modern 'more-electric' aircraft demand increased levels of electrical power as non-propulsive power systems are replaced with electrical equivalents. This electrical power is provided by electrical generators, driven via a mechanical transmission system, from a rotating spool in the gas turbine core. A wide range of electrical loads exist throughout the aircraft, which may be pulsating and high powered, and this electrical power demand is transferred though the generators to produce a torque load on the drivetrain. The mechanical components of the drivetrain are designed for minimum mass and so are susceptible to fatigue, therefore the electrical loading existing on modern airframes may induce fatigue in key mechanical components and excite system resonances in both mechanical and electrical domains. This electro-mechanical interaction could lead to a reduced lifespan for mechanical components and electrical network instability.This project investigates electro-mechanical interaction in the electrical power offtake from large diameter aero gas turbines. High fidelity modelling of the drivetrain, and generator, allow the prediction of system resonances for a generic gas turbine-generator system. A Doubly-Fed Induction Generator (DFIG) is considered and modelled. DFIGs offer opportunities due to their fast dynamics and their ability to decouple electrical and mechanical frequencies (e.g. enabling a constant frequency electrical system with a variable speed mechanical drive). A test platform is produced which is representative of a large diameter gas turbine and reproduces the electro-mechanical system behaviour. The test platform is scaled with respect to speed and power but maintains realistic sizing between component dimensions which include: a gas turbine mechanical spool emulation, transmission driveshafts and gearbox, and accessory loads such as a generator. This test platform is used to validate theoretical understanding and suggest alternative mechanical configurations, and generator control schemes, for the mitigation of electro-mechanical interaction.The novel use of a DFIG and an understanding of electro-mechanical interaction allow future aircraft designs to benefit from the increased electrification of systems by ensuring that sufficient electrical power can be provided by a robust gas turbine-generator system.
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Almada, Janaina Barbosa. "Modeling, Control and Management of Microgrids Operation with Renewable Sources." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11122.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico<br>Nowadays, the distribution networks of electricity are the segment of the electrical power systems that has experienced more changes, due in particular to the presence of distributed generation and the technological advances in the areas of instrumentation, automation, measurement, information technology and comunication. This work aims to present the modelling, the control and the operation management of a group of small-scale energy resources connected to the low voltage, which coordinated form a microgrid. The microgrid energy resources are solar photovoltaic sources, wind energy based on double fed induction generator and hydrogen fuel cell, and a storage system with batteries. Two conceptions are developed: a single-phase microgrid and a three-phase microgrid, both operating in connected mode and isolated from the utility. Each energy resource is connected to a point of common coupling through power converters. For each converter was designed a set of control loops. The master-slave strategy was used to control the converters and to microgrid management. In master-slave configuration only the master converter is designed to be the voltage reference and others operate as a current source. For managing the steady state operation of microgrids different operating scenarios were considered, with variation of load and generation levels, as well as changes in tariff flags, for load supply with economy and sources operating at maximum efficiency. The proposed systems operate satisfactorily fulfill the requirements of utility for synchronization and disconnection. The injected currents are below the allowed distortion level. In stand-alone mode, the system voltage remains within the appropriate level of amplitude and frequency.<br>Atualmente, as redes de distribuiÃÃo de energia elÃtrica sÃo o segmento dos siste-mas elÃtricos de potÃncia que mais tem experimentado mudanÃas, devido, em es-pecial, à presenÃa da geraÃÃo distribuÃda e aos avanÃos tecnolÃgicos nas Ãreas de instrumentaÃÃo, automaÃÃo, mediÃÃo, tecnologia da informaÃÃo e comunicaÃÃo. Este trabalho tem por objetivo apresentar a modelagem, o controle e o gerenciamento da operaÃÃo de um conjunto de recursos energÃticos de pequeno porte, conectados à baixa tensÃo, que coordenados formam uma microrrede. Os recursos energÃticos da microrrede sÃo fontes solar fotovoltaica, eolielÃtrica com gerador de induÃÃo de dupla alimentaÃÃo e cÃlula combustÃvel a hidrogÃnio, e um sistema de armazenamento de energia a baterias. Duas concepÃÃes de microrredes sÃo desenvolvidas: microrrede monofÃsica e microrrede trifÃsica, ambas operando em modo conectado e isolado da rede elÃtrica principal. Cada recurso energÃtico à conectado a um ponto comum de conexÃo atravÃs de conversores de potÃncia. Para cada conversor foi projetado um conjunto de malhas de controle. A estratÃgia mestre-escravo foi usada para o controle dos conversores e gerenciamento da microrrede. Na configuraÃÃo mestre-escravo apenas o conversor mestre à designado para ser a referÃncia de tensÃo que os outros conversores necessitam para operarem como fonte de corrente. Para o gerenciamento da operaÃÃo das microrredes em regime permanente, foram considerados diferentes cenÃrios de operaÃÃo, com variaÃÃo de nÃveis de carga e de geraÃÃo, bem como variaÃÃo de bandeiras e postos tarifÃrios, visando atender a carga com economicidade e fontes operando em mÃxima eficiÃncia. Os sistemas propostos operam de forma satisfatÃria obedecendo aos requisitos da concessionÃria para a sincronizaÃÃo e desconexÃo. As harmÃnicas de corrente injetada estÃo abaixo do nÃvel de distorÃÃo permitido. No modo isolado, a tensÃo dos sistemas permanece dentro do nÃvel adequado de amplitude e frequÃncia.
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Naranjo, Rafael Ricardo Avila. "Alternatives to the use of the crowbar circuit in DFIG based wind turbines during balanced voltage dips." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-30122014-112624/.
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Most of the modern wind turbines are based on doubly fed induction generators (DFIG), with a back to back power converter connecting the rotor to the network. It is known that voltage dips at the stator terminals can cause overcurrents in the rotor windings, which could threaten the converter integrity. In order to protect the converter, several strategies have been proposed in technical literature, requiring in some cases the converter deactivation, which disables the control that the converter has over the power transference between the generator and the system. This last is not a desirable behavior since it can put on risk the voltage stability of the electric system. It is the aim of this dissertation to introduce and compare five of those protection strategies, through the computational simulation of their performance in case of balanced voltage dips. In order to achieve this, the electromagnetic dynamic model of the DFIG was theoretically developed, as well as the models of the strategies of interest. Subsequently, the computational model of the system was assembled in the software Matlabs Simulink to finally perform the desired simulations and its corresponding analysis.<br>A maioria das turbinas eólicas modernas é baseada em geradores de indução duplamente alimentados (GIDE), com um back to back conversor de energia que liga o rotor para a rede. Sabe-se que as quedas de tensão nos terminais do estator podem causar sobrecorrentes nos enrolamentos do rotor, que podem ameaçar a integridade do conversor. A fim de proteger o conversor, várias estratégias têm sido propostas na literatura técnica, exigindo, em alguns casos, a desativação do conversor, o qual desativa o controlo do conversor, que possui ao longo da transferência de energia entre o gerador e o sistema. Este último não é um comportamento desejável, uma vez que pode colocar em risco a estabilidade de tensão do sistema elétrico. É o objetivo desta dissertação apresentar e comparar cinco dessas estratégias de proteção, através da simulação computacional de seu desempenho em caso de quedas de tensão equilibrada. A fim de alcançar este objetivo, o modelo dinâmico eletromagnética do DFIG teoricamente foi desenvolvido, bem como os modelos das estratégias de interesse. Subsequentemente, o modelo computacional do sistema foi montado no software Simulink do Matlab para finalmente executar as simulações desejadas e sua análise correspondente.
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Baggu, Murali Mohan. "Advanced control techniques for doubly fed induction generator-based wind turbine converters to improve low voltage ride-through during system imbalances." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Baggu_09007dcc806684bd.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.<br>Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 27, 2009) Includes bibliographical references (p. 126-130).
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Khamaira, Mahmoud Yousef. "A New Converter Station Topology to Improve the Overall Performance of a Doubly Fed Induction Generator-Based Wind Energy Conversion System." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/2397.
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This thesis presents a reliable and cost effective technique that calls for reconfiguration of the existing converters of a typical Doubly Fed Induction Generator to include a coil of low internal resistance. A coil within the DC link is the only hardware component required to implement this technique. With a proper control scheme, activated during fault conditions, this coil can provide the same degree of performance as a superconducting magnetic energy storage unit during fault conditions.
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Valencia, Guerrero Gabriel Andrés. "Análise em regime permanente de parques eólicos com máquinas SCIG e DFIG." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/100164.
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A geração de energia elétrica com fontes renováveis está em aumento e uma das que tem maior crescimento é a eólica. A instalação das máquinas que aproveitam este recurso pode trazer alguns problemas para a rede elétrica devido à intermitência da velocidade do vento. O presente trabalho tem por objetivo analisar o comportamento de dois tipos de aerogeradores que utilizam gerador de indução e sua interação com o sistema elétrico de potência. Os aerogeradores assíncronos analisados são o de velocidade variável com gerador de indução duplamente alimentado (Doubly-Fed Induction Generator-DFIG) e o de velocidade fixa com gerador de indução de rotor de gaiola de esquilo (Squirrel Cage Induction Generator-SCIG). O caso de estudo está baseado no parque eólico Jepirachi na Colômbia, o qual na atualidade tem aerogeradores de velocidade fixa. Para isto inicialmente foi feita a modelagem do parque eólico considerando alguns parâmetros dos aerogeradores comerciais de velocidade variável e velocidade fixa, junto com os principais componentes da rede elétrica da região para obter uma aproximação da mesma. Posteriormente realizaram-se simulações computacionais para obter o comportamento do sistema elétrico de potência alimentado por estes tipos de aerogeradores. Finalmente, foi realizada uma análise dos efeitos que produzem cada tipo de máquina, no fluxo de potência e no nível de tensão da rede elétrica funcionando em regime permanente, considerando os distúrbios ocasionados pelas mudanças da velocidade do vento.<br>The generation of electricity from renewable sources is increasing, one of the largest growth is the wind power. However the installation of the machines that leverage this resource could bring some problems to the grid due to the intermittency of the wind speed. This work analyzes the behavior of variable speed wind turbines with Doubly-Fed Induction Generator (DFIG) and fixed-speed wind turbines with Squirrel Cage Induction Generator (SCIG). The case study is based in Jepirachi wind farm in Colombia, that at the present has fixed-speed wind turbines with Squirrel Cage Induction Generator (SCIG). To do this study, initially the modeling of the wind farm considering some parameters of commercial wind turbines with variable speed and fixed speed, also modeling the main components of the electric grid of the region to obtain an approximation of it, after computer simulations we made in order to obtain the behavior of the electric power system powered by these types of turbines. Finally the analysis of the effects produced by each type of machine, in the power flow and the voltage level of the grid operating in steady state, but considering the disturbances caused by changes in wind speed are made.
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Gogas, Kyriakos. "Design of a robust speed and position sensorless decoupled P-Q controlled doubly-fed induction generator for variable-speed wind energy applications." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99762.
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Wind energy is a relatively young but rapidly expanding industry. In order for wind generation to be cost effective, it must produce energy at a minimum cost per dollar of investment. Performance characteristics such as power output versus wind speed must be optimized in order to compete with other energy sources. Also, if the utility uses wind power for a part of its generation, the output power of these turbines must have the same high quality and reliability when it enters the utility grid. The ability to vary operating speed is important in wind generation because it allows for an optimization of the transfer of power from the wind to the turbine shaft. Doubly-fed induction generators (DFIG) are an interesting solution for variable-speed systems with limited variable speed range, and are typically used in wind energy conversion systems.<br>The objectives of this thesis are to implement a decoupled P-Q control of a DFIG that does not rely on mechanical sensors and to design a speed and position sensorless algorithm that is robust to variations of the values of the machine parameters. The sensorless DFIG control algorithm presented in this thesis is based on a modified phasedlock loop with an improved positioning algorithm. With the measured stator voltages, stator and rotor currents, the speed and position of the DFIG are estimated. The speed is estimated independent of machine parameters, which results in a significant improvement in speed control robustness to parameter variations. In addition, the algorithm avoids using differentiation, which significantly improves its immunity to noise and does not require the measurement of the rotor voltages. Also, it is shown that the positioning algorithm has an improved operation in generator mode. Although the accuracy of the positioning algorithm is depended on machine parameters; it is shown with the designed controller that the P-Q decoupled control is robust to changes of machine parameters. Theoretical and simulation results are validated on an experimental setup.
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Melo, Fábio Alexandre Amorim. "Doubly-fed induction generator wind turbine system." Master's thesis, 2019. http://hdl.handle.net/1822/73469.
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Dissertação de mestrado em Eletrónica Industrial e Computadores<br>The production of electrical energy resorting to fossil fuels contributes to the increase in the emissions of greenhouse gases, more specifically CO2, for the atmosphere. In the last decades, there have been increasing environmental concerns regarding the current status of the electrical energy production, which has increased the investment in the renewable energies, in hopes for a more sustainable energy, without the emission of greenhouse gases. One of these renewable energies, is wind energy, which has enormous potential in Portugal, and that has been getting a bigger active role in the world.
The concept of wind energy production with a variable speed generator has gotten a lot of attention due to the fact that the control methods used need to be improved and more efficient. As such, this project is focused on the development of a control system for a doubly-fed induction generator (DFIG), so that it is possible to extract the maximum power possible. To make this possible, it is used a back-to-back converter composed of two converters, a AC-DC converter (Alternating Current – Direct Current), called rectifier, and a DC-AC converter (Direct Current – Alternating Current), called inverter, and a DC-link capacitor connected in between them. These converters are controlled by means of a control circuit, and are inserted in a wind turbine generator system (WTGS). The system is tested in computer simulation environment to prove the concept.
To develop this project, it is necessary a study of each component of the WTGS, specially the DFIG and its mathematical model, to make possible the development of the control system as well as all of the interface circuits.<br>A produção de energia Elétrica com recurso a combustíveis fósseis contribui para o aumento das emissões dos gases de efeito de estufa, mais especificamente de CO2, para a atmosfera. Nas últimas décadas tem havido maiores preocupações ambientais no que diz respeito ao estado atual da produção de energia elétrica, o que tem aumentado o investimento nas energias renováveis, na esperança de se obter uma energia mais sustentável, sem a emissão dos gases de efeito de estufa. Uma dessas energias renováveis, é a energia eólica, que tem enorme potencial em Portugal, e que tem tomado cada vez mais um papel ativo maior no mundo.
O conceito de produção de energia eólica com um gerador de velocidade variável tem recebido muita atenção devido ao facto de os métodos de controlo utilizados terem que ser melhorados e mais eficientes. Assim sendo, nesta dissertação é desenvolvido um sistema de controlo para um gerador indutivo duplamente alimentado (DFIG), por forma a extrair o máximo de potência possível. Para que tal seja possível, é utilizado um conversor back-to-back composto por dois conversores, um conversor AC-DC (Corrente Alternada – Corrente Contínua), denominado retificador, e um por um conversor DC-AC (Corrente Contínua – Corrente Alternada), denominado inversor, e por um condensador DC-link ligado entre ambos. Estes conversores são controlados através de um circuito de controlo, e inseridos num sistema gerador de turbina eólica (WTGS). O sistema é testado em contexto de simulação em computador para provar o conceito.
Para realizar esta dissertação, é necessário um estudo teórico de cada componente do WTGS, em especial do gerador DFIG e do seu modelo matemático, para possibilitar o desenvolvimento do sinal de controlo e de todo o circuito de interface.
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Chou, Chien-Hung, and 周建宏. "Control of Doubly-Fed Induction Generator for Wind Power Generation." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/8394x3.
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碩士<br>國立交通大學<br>電控工程研究所<br>101<br>In this thesis, we analysised the impact of grid voltage sags on Doubly-Fed Induction Generator(DFIG). The over current in transient state will cause damage to power electronic devices without proper control or protection. Therefore, it is necessary to use the protection units and study the control. Nowadays, the generator system usually use the Crowbars to avoid over current pass through converters. Although it can properly work during voltage dips, but, if voltage fluctuations are frequent, excessive switching will cause control difficulties and ineffieicney in power tracking.
The purpose of the thesis is to improve control scheme under lightly three phase voltage dip. System can keep connected to grid during fault occurred. Simulation was buid in Matlab/Simulink, using an induction generator and mechanical turbine math model. Different rotor speed(sub-synchronous and super-synchronous) are tested to observe system responses in three phase voltage faults, and the result are analysed at last.