To see the other types of publications on this topic, follow the link: Variable Speed Wind Turbines.
Dissertations / Theses on the topic 'Variable Speed Wind Turbines'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Variable Speed Wind Turbines.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Goodfellow, David. "Variable speed operation of wind turbines." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/7822.
Full textAbstract:
This work describes a control system in which a cycloconverter is connected between the secondary windings of a three phase induction machine and the a. c. mains supply to give variable speed sub- and super –synchronously. In order to control the system smoothly in an asynchronous mode a secondary emf signal generator has been designed, which enables the cycloconverter to operate in synchronism with the emf induced in the secondary windings of the machine. A computer programme has been written which calculates the required firing angles for the cycloconverter to produce secondary current in phase with the secondary emf in the machine. An electronic system has been built which ensures that these firing angles are used by the cycloconverter during actual operation. A cycloconverter has been built, using an effective six phases of mains supply, and has been successfully operated over a range of 20% about synchronous speed in both generating and motoring modes. Results show the ability of the cycloconverter to drive the machine up from standstill as a motor to just below 20% subsynchronous speed. An on-line computer simulation of a wind turbine has been developed which enables an assessment of variable speed generation applied to wind turbines to be achieved. This simulation, in connection with a d. c. machine and thyristor controller, can be used to drive the shaft of the induction machine and assess operation of the cycloconverter control scheme under actual wind turbine operating conditions.
2
Dadashnialehi, Ehsan. "Modeling And Control of Variable Speed Wind Turbines." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1356372607.
Full text
3
Iqbal, Muhammad Tariq. "Dynamic control strategies for fixed and variable speed wind turbines." Thesis, Imperial College London, 1994. http://hdl.handle.net/10044/1/7737.
Full text
4
Bourlis, Dimitrios. "Control algorithms and implementation for variable speed stall regulated wind turbines." Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/28800.
Full textAbstract:
In this research control algorithms and implementation for variable speed stall regulated wind turbines are presented. This type of wind turbine has a simpler and more robust construction and can have lower requirements for maintenance than the existing pitch regulated wind turbines. Due to these features these wind turbines can have reduced cost, which is a crucial parameter especially for large scale wind turbines. However, this type is not commercially available yet due to existing challenges in its control. In this research a complete control scheme for variable speed stall regulated wind turbines has been developed and implemented in a fully dynamic hardware-in-loop simulator for variable speed wind turbines. The simulator was developed as part of the project in order to validate the designed control algorithms. The developed control system uses novel adaptive methods in order to maximize the energy production of the wind turbines at below rated wind speeds as well as to control the power of the wind turbine at above rated wind speeds. In addition, several types of controllers including robust controllers have been used and tested, which resulted to novel control solutions for stall regulated wind turbines. The main advantage of the proposed control method is that it uses existing hardware without requiring additional sensors, so it more effectively exploits information coming from measurements available in existing wind turbine converters. Through software and hardware simulations the proposed control algorithms seem to be quite promising and give confidence for the future development of variable speed stall regulated wind turbines.
5
Markou, Helen. "Generic controller for a class of variable speed, stall regulated wind turbines." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401395.
Full text
6
Ahmed, Ibrahim. "Comparative evaluation of different power quality issues of variable speed wind turbines." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15920.
Full textAbstract:
The generation of wind energy deliberately becomes a significant part of generated electrical power in developed nations. Factors like fluctuation in natural wind speed and the use of power electronics present issues related power quality in wind turbine application. Following to the fact that there have been remarkable increase of wind energy in the electrical energy production worldwide, the effect on power quality and power system stability caused by wind power is considered significant, and hence the evaluation of this effect is crucial and obligatory. In order to examine and evaluate the characteristics of power quality of grid-integration of wind power in a persistent and authentic manner, several guidelines were introduced and established. One of the widely used guideline to define power quality of wind turbine is IEC standard 61400-21. Moreover, power system operator demands wind turbines to tolerate a certain voltage dip in some countries. The wind turbines concepts such as doubly-fed induction generator wind turbine and the direct driven wind turbine wind turbine with a permanent magnet synchronous generator are considered as the most promising concepts among other wind turbine types since they can operate in wide range of wind speed. The major goal of this PhD work is to examine the power quality character aspects of these wind turbine concepts. The power quality problems were calculated according to that devised by IEC- 61400-21 and then compared afterwards. The research includes the evaluation of the following power quality characteristics: voltage dip response, current harmonics distortion, control of active and reactive power and voltage flicker. Besides the IEC-standard 61400-21, the study also looks into the short-circuit current and fault-ride through with specifications provided by some grid codes, as power system stability is greatly influenced by these aspects. In order to achieve the research's goal, a reliable dynamic model of wind turbine system and control are required. Thus a complete model for both wind turbines systems was developed in PSCAD/EMTDC simulation-program which is the fanatical power system analysis tool, which can achieve a complete simulation of the system dynamic behaviour from the wind turbine. Two controllers are adopted for wind turbine system, converter control and pitch angle control. The converter controlled by a vector control in order to regulate the active and the reactive power whereas the pitch control scheme is put to function to limit the aerodynamic power in high wind speed. The ability of providing adequate state steady and dynamic performances are what wind turbine assures, as examined by simulation results, and via this, problems related to power quality caused by integrating wind turbines to the grid can be studied by wind turbine model.
7
Hand, M. Maureen. "Variable-speed wind turbine controller systematic design methodology : a comparison of non-linear and linear model-based designs /." Golden, CO : National Renewable Energy Laboratory, 1999. http://www.nrel.gov/docs/fy99osti/25540.pdf.
Full text
8
Licari, John. "Control of a variable speed wind turbine." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/46516/.
Full textAbstract:
Stop signal task of response inhibition, I find that response inhibition (stopping) is slowed in the presence of angry facial expressions, and such slowing is greater in individuals high in trait neuroticism. Further, as predicted, the influence of neuroticism is moderated by individual differences in emotion regulation, such that good emotion regulation ‘buffers’ the impact of neuroticism. The implications of these findings for current cognitive models of threat-processing are discussed.
9
Ramtharan, Gnanasambandapillai. "Control of variable speed wind turbine generators." Thesis, University of Manchester, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556174.
Full text
10
Koc, Erkan. "Modeling And Investigation Of Fault Ride Through Capability Of Variable Speed Wind Turbines." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612534/index.pdf.
Full textAbstract:
Technological improvements on wind energy systems with governmental supports have increased the penetration level of wind power into the grid in recent years. The high level of penetration forces the wind turbines stay connected to the grid during the disturbances in order to enhance system stability. Moreover, power system operators must revise their grid codes in parallel with these developments. This work is devoted to the modeling of variable speed wind turbines and the investigation of fault ride trough capability of the wind turbines for grid integration studies.
In the thesis, detailed models of different variable speed wind turbines will be presented. Requirements of grid codes for wind power integration will also be discussed regarding active power control, reactive power control and fault ride through (FRT) capability. Investigation of the wind turbine FRT capability is the main focus of this thesis. Methods to overcome this problem for different types of wind turbines will be also explained in detail. Models of grid-connected wind turbines with doubly-fed induction generator and permanent magnet synchronous generator are implemented in the dedicated power system analysis tool PSCAD/EMTDC. With these models and computer simulations, FRT capabilities ofvariable speed wind turbines have been studied and benchmarked and the influences on the grid during the faults are discussed.
11
Lloyd, Simon H. "Variable speed control of a small wind turbine." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/14376.
Full textAbstract:
An electronic controller has been developed for a wind turbine which uses a passive pitching mechanism and a permanent magnet generator. The turbine rotor is a 3 bladed, down wind horizontal axis design with a diameter of 3.4m. The machine, manufactured by Proven Engineering Ltd., produces 2.2kW at a wind speed of 12m/ s and a rotor speed of 30Orpm. Passive regulation is achieved through a variation of blade pitch controlled by balancing the aerodynamic, centrifugal and spring forces acting on each blade. A production machine has been instrumented and laboratory and field test data collected; from this data a mathematical model has been derived. A power electronic interface (DC-DC booster) was designed and built to transform the generator voltage to a fixed DC voltage. A controlled load is used together with feedback to the booster to set an appropriate load resistance according to operating conditions. Current demand from the generator (used in the control) is derived either from the difference between the rotor speed and a reference speed, or directly as a function of the rotor speed (feed-forward control). This thesis deals with the design and testing of the 3 compensators which govern the wind turbine control using both simulated and measured results. The overall objective of the controller is to maximise the energy yield from the wind turbine, subject to realistic constraints imposed by the power electronic design in the context of this particular design.
12
Gase, Zachary M. "Below-Rated Control of Swept-Blade Wind Turbines." Scholarly Commons, 2016. https://scholarlycommons.pacific.edu/uop_etds/225.
Full textAbstract:
Modelling studies have shown that 1.5 and 3.0 MW wind turbines with blade sweep have an increased annual energy production (AEP) of approximately 5% when compared to straight-blade wind turbines. The objective of the research was to further increase below-rated, variable speed, power capture when using swept-blades. When operating in the variable speed region, the turbine’s torque is proportional to the square of the generator speed, and k is the proportionality constant (T = kΩ 2 ). Initial studies indicated that the value of k needed to be lowered from the original value to increase AEP. This proved to be slightly beneficial for the 3.0 MW turbine but not for the 1.5 MW turbine. The optimal tip speed ratio was too high for both turbines and limited the ability to increase AEP. Original swept-blade chords were designed to fit a linear pattern for manufacturing purposes, but it is believed this is no longer a necessary constraint. The blades were redesigned to have a non-linear chord distribution, which is based on the Betz optimal design method, and the resultant increase in solidity proved to be the solution for slowing down the blades’ rotational speed. The change in chord design proved to be beneficial for both 1.5 and 3.0 MW wind turbines and had immediate, measurable increases to AEP. An effort to further increase AEP was then conducted by using an alternative torque-speed controller, which used a different equation to relate speed and torque. This method only resulted in an increase of AEP for the 1.5 MW turbine. In conclusion, the highest recorded AEP increases from straight-blade values were 6.9% and 8.9% for the 1.5 and 3.0 MW turbines, respectively. The 1.5 MW turbine benefited from the custom controller and redesigned chords, whereas the 3.0 MW turbine only benefited from redesigned chords.
13
Mathiopoulos, Athanasios. "Development of a self-tuned drive-train damper for utility-scale variable-speed wind turbines." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/9922.
Full textAbstract:
This thesis describes the development of a procedure that tunes a wind turbine drivetrain damper (DTD) automatically. This procedure, when integrated into the controller of any utility-scale variable-speed wind turbine, will allow the turbine to autonomously and automatically tune its DTD on site. In practice this means that the effectiveness of the damper becomes independent on the accuracy of the model or the simulations used by the control engineers in order to tune the damper. This research is motivated by the fact that drive-train failures are still one of the biggest problems that stigmatises the wind turbine industry. The development of an automatically tuned DTD that alleviates the drive-train fatigue loads and thus increases the reliability and lifetime of the drive-train is thus considered very beneficial for the wind turbine industry. The procedure developed begins by running an experimental procedure to collect data that is then used to automatically system identify a linear model describing the drivetrain. Based on this model a single band-pass filter acting as a DTD is automatically tuned. This procedure is run for a number of times, and the resulting DTDs are compared in order to select the optimal one. The thesis demonstrates the effectiveness of the developed procedure and presents alternative procedures devised during research. Finally, insight into future work that could be performed is indicated in the last chapter of the thesis.
14
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.
Full textAbstract:
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.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.
15
Bu, Yiming. "Switching linear parameter-varying control of a variable-speed wind turbine." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1596455.
Full textAbstract:
For variable-speed wind energy conversion systems, control objectives may be different in partial and full load regions (or in low and high wind speed regions). Typical control objectives are to maximize the energy capture in low wind speeds, and to maintain the generated power and the rotational turbine speed within safety limits during high wind speeds. In such a case, it is difficult to design a single robust controller covering both partial load and full load conditions. This paper presents a systematic switching control method for a variable-speed variable-pitch wind turbine over a wide wind speed region. The whole framework is based on the linear parameter-varying (LPV) control theory, which is an extension of robust control for linear systems to nonlinear ones.
Two LPV controllers are designed, each suitable in a different wind speed region. A hysteresis switching logic is applied to guarantee the stability when the switching event occurs between the two controllers. Nonlinear simulations are conducted to demonstrate the proposed control scheme.
16
Irandoost, Hamid. "Fault Diagnosis of a Variable-Speed Wind Turbine via Support Vector Machines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15501/.
Full textAbstract:
In recent years, wind energy is considered as the most practical substitute energy to replace the fossil fuels. Wind turbines are massive and installed in locations, where a non-planned maintenance is very costly. Therefore, a fault-tolerant control system that is able to maintain the wind turbine connected after the occurrence of certain faults can avoid major economic losses.
To keep the wind turbine operational or at least safe, in severe cases, a reliable fault diagnosis methodology has to be exploited. It must detect, in the required time, any deviation of the system behaviour from its ordinary case, identify the location and type of the fault and reconfigure the control system to accommodate the so-called discrepancy.
To achieve the above goals, a vast number of methods have been suggested by many researchers all around the world. In this thesis, the promising classification framework of the Support Vector Machines is applied to fault detection for variable speed turbines, highlighting its features. In this regard, different fault scenarios are imposed on a benchmark model of a horizontal-axis wind turbine to check the functionality of the mentioned fault detector and the control reconfiguration module.
17
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/.
Full textAbstract:
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.
18
Fateh, Fariba. "Nonlinear control schemes for extremum power seeking and torsional vibration mitigation in variable speed wind turbine systems." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20553.
Full textAbstract:
Doctor of PhilosophyDepartment of Electrical and Computer Engineering
Don Gruenbacher
Warren White
This dissertation presents nonlinear control schemes to improve the productivity and lifespan of doubly fed induction generator (DFIG)-based and permanent magnet generator (PMG)-based variable speed wind turbines. To improve the productivity, a nonlinear adaptive control scheme is developed to maximize power capture. This controller consists of three feedback loops. The first loop controls electrical torque of the generator in order to cancel the nonlinear term of the turbine equation of motion using the feedback linearization concept. The nonlinearity cancelation requires a real-time estimation of aerodynamic torque. This is achieved through a second loop which estimates the ratio of the wind turbine power capture versus the available wind power. A third loop utilizes this estimate to identify the shaft speed at which the wind turbine operates at a greater power output. Contrary to existing techniques in literature, this innovative technique does not require any prior knowledge of the optimum tip speed ratio. The presented technique does not need a dither or perturbation signal to track the optimum shaft speed at the maximum power capture. These features make this technique superior to existing methods. Furthermore, the lifespan of variable speed wind turbines is improved by reducing stress on the wind turbine drivetrain. This is achieved via developing a novel vibration mitigation technique using sliding-mode control theory. The technique measures only generator speed as the input signal and then passes it through a high-pass filter in order to extract the speed variations. The filtered signal and its integral are then passed through identical band-pass filters centered at the dominant natural frequency of the drivetrain. These two signals formulate a sliding surface and consequently a control law to damp the drivetrain torsional stress oscillations caused by electrical and mechanical disturbances. This technique provides a robust mitigation approach compared with existing techniques. These control schemes are verified through holistic models of DFIG- and PMG-based wind turbines. Except for wind turbine aerodynamics, for which an existing simulator is used, the developed models of all components including DFIG, PMG, converters, multi-mass drivetrain, and power line are presented in this dissertation.
19
Rosmin, Norzanah. "Internal Model Control (IMC) design for a stall-regulated variable-speed wind turbine system." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/16850.
Full textAbstract:
A stall-regulated wind turbine with fixed-speed operation provides a configuration which is one of the cheapest and simplest forms of wind generation and configurations. This type of turbine, however, is non-optimal at low winds, stresses the component structure and gives rise to significant power peaks during early stall conditions at high wind speeds. These problems can be overcome by having a properly designed generator speed control. Therefore, to track the maximum power locus curve at low winds, suppress the power peaks at medium winds, limit the power at a rated level at high winds and obtain a satisfactory power-wind speed curve performance (that closely resembles the ideal power-wind speed curve) with minimum stress torque simultaneously over the whole range of the wind speed variations, the availability of active control is vital. The main purpose of this study is to develop an internal model control (IMC) design for the squirrel-cage induction generator (SCIG), coupled with a full-rated power converter of a small (25 kW), stall-regulated, variable-speed wind-turbine (SRVSWT) system, which is subject to variations in the generator speed, electromagnetic torque and rotor flux. The study was done using simulations only. The objective of the controller was to optimise the generator speed to maximise the active power generated during the partial load region and maintain or restrict the generator speed to reduce/control the torque stress and the power-peaking between the partial and full load regions, before power was limited at the rated value of 25 kW at the full load region. The considered investigation involved estimating the proportional-integral (PI) and integral-proportional (IP) controllers parameter values used to track the stator-current producing torque, the rotor flux and the angular mechanical generator speed, before being used in the indirect vector control (IVC) and the sensorless indirect vector control (SLIVC) model algorithms of the SCIG system. The design of the PI and IP controllers was based on the fourth-order model of the SCIG, which is directly coupled to the full-rated power converter through the machine stator, whereas the machine rotor is connected to the turbine rotor via a gearbox. Both step and realistic wind speed profiles were considered. The IMC-based PI and IP controllers (IMC-PI-IP) tuning rule was proven to have smoothened the power curve and shown to give better estimation results compared to the IMC-based PI controllers (IMC-PI), Ziegler-Nichols (ZN) and Tyreus-Luyben (ZN) tuning rules. The findings also showed that for the SRVSWT system that employed the IVC model algorithm with the IMC-PI-IP tuning rule, considering the application of a maintained/constant speed (CS) strategy at the intermediate load region is more profitable than utilizing SRVSWT with the modified power tracking (MoPT) strategy. Besides that, the finding also suggested that, for the IMC-PI-IP approach, the IVC does provide better power tracking performance than the SLIVC model algorithm.
20
Al, Tubi Issa. "Effects of variable load and rotational speed conditions on gear micropitting in wind turbine gearboxes." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7173/.
Full textAbstract:
Micropitting damage is one of the failure modes commonly observed on gears and bearings in wind turbine (WT) gearboxes. It can lead to destructive failures which, in turn, lead to unplanned WT shutdown and expensive replacement. This research provides an insight into effects of variable load and rotational speed condition on micropitting in WT gearboxes. It also investigates in detail the occurrence of micropitting in WT gearboxes under various operational conditions using an experimental study and an analytical study, employing two methods: an analytical method based on selected SCADA (Supervisory Control and Data Acquisition) data and a probabilistic modelling of SCADA data method. This study focuses predominantly on the micropitting of the high speed shaft (HSS) gear of a WT gearbox operating under nominal and varying load and speed conditions. The SCADA datasets recorded from WT gearboxes in operation are used. Based on the SCADA data, the recorded WT generator power output and generator rotational speed are used to obtain the shaft torque of the HSS driven gear. Based on ISO Technical Report ISO/TR 15144-1 (2010) and various ISO gear standards, an analytical study is carried out to assess the risk of gear micropitting by determining the contact stress, sliding parameter, local contact temperature, lubricant film thickness and specific lubricant film thickness along the line of action of the gear tooth contact by considering the WT operating load and speed conditions. The experimental study investigates the initiation and progression of gear micropitting when gear tooth flanks are subjected to varying torque levels at a constant rotational speed. The study is conducted by carrying out gear micropitting testing and surface inspection, as well as validating implementing analytical evaluations by comparing the obtained results with that obtained by using various commercial software packages based on ISO Technical Report ISO/TR 15144-1 and AGMA 925-A03 standard. The surface inspection of tested gears is carried out using procedures of surface roughness measurement, replica of surface micropits and profile deviation measurement. The analytical results are compared to the experimental results to predict the occurrence of gear micropitting through evaluating tooth contact stress, sliding parameter, local contact temperature and specific lubricant film thickness at different points along the gear tooth flank. The surface roughness measurements, obtained from the tested gears after each cycle run under specific torque levels, are considered in the analytical investigation. The gear testing results show that micropitting initiates at the pinion dedendum, but escalates at the addendum because of the greater severity of progressive micropitting at the mating wheel dedendum. The micropitting initiates at the beginning of the tip relief area of the pinion and at the root of the pinion with which the wheel tip relief area first starts to mesh. The analytical results confirm that maximum contact stresses and minimum lubricant film thickness occur at these areas. The lubricant film thickness varies considerably because of changes in surface roughness after the gears undergo various running cycles under varying torque levels. The validation process reveals that the ISO/TR 15144-1 results provide a better correlation with experimental results, as compared to AGMA 925-A03 results. The analysis of WT operational condition using selected one month SCADA data identifies three regions of relationships between the generator power and wind speed, the generator speed and wind speed variations. Non-uniform distributions of contact stress, contact temperature and lubricant film thickness over the tooth flank are observed. This is due to the conditions of torque and rotational speed variations and sliding contact along the gear tooth flanks. The lubricant film thickness varies along the tooth flank and is at its lowest when the tip of the HSS wheel gear engages with the root of the HSS driven gear. The lubricant film thickness increases with the increase of the rotational speed and decreases as the torque and sliding increase. It can be concluded that micropitting is most likely to initiate at the dedendum of pinion gear. The lowest film thickness occurs when the torque is high and the rotational speed is at its lowest, which may cause direct tooth surface contact. In low torque condition, the varying rotational speed condition may cause a considerable variation in lubricant film thickness, thus interrupting the lubrication, which may result in micropitting. Finally, a probabilistic analysis is carried out to investigate the probabilistic risk of tooth flank micropitting failure using the entire SCADA datasets. A random number of datasets of smaller sizes of gear shaft torque and rotational speed are generated to substitute for the large amounts of data in the original SCADA datasets. Based on the selected random number datasets, the effect of variations in gear shaft torque and rotational speed on the probabilistic characteristics of gear tooth flank micropitting is investigated. The study shows that the HSS driven pinion gear is subject to overloading conditions, resulting in maximum contact stresses higher than the allowable contact stress of the material. Thus, the high torque value, which occurs at low rotational speed according to the data analysis, is the main cause of micropitting in WTs as it leads to high contact stress. In addition, the results of the analysis of specific lubricant film thickness show that there is a considerable risk of micropitting at the dedendum region of gear teeth under variable operational condition.
21
El-Helw, Hadi Maged. "Investigation of the compliance of fixed and variable speed wind turbines to the new UK grid code and the effect of variable frequency operation on optimizing converter rating." Thesis, Staffordshire University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492946.
Full textAbstract:
This thesis deals with the compliance of fixed speed and variable speed wind turbines based on doubly fed induction generator (DFIG) with the new UK grid code in terms of reactive power capability and fault ride through capability. Moreover, a new technique which enables the converter rating reduction of the DFIG based on variable frequency operation is proposed and evaluated in this thesis.
22
Andersson, Oskar. "Inclusion of Wind Turbines into Frequency Support Services : Exploring frequency stability issues and comparing regulation power market products." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-435076.
Full textAbstract:
There is a trend in Sweden towards increasing the electricity production from renewable energy sources in the electric grid. The increased share of renewables could be seen as essential for Sweden to be able to meet the obligated climate goals. Integration of renewables will enable Sweden to be a progressive part in reducing greenhouse gases and decreasing the global warming. However, one issue with renewable energy sources is the inverter governed production. This, together with the decommission of larger synchronous generators, results in decreasing the inertia and increasing the instability inthe grid. This thesis is dedicated to elaborating on frequency stability issues and investigating how Variable Speed Wind Turbines (VSWT) could contribute towards stabilized operation when included in frequency support services. The study is generated through an extensive research process where focus areas are identified. Questions are purposed and then discussed through interviews with experienced people in the field. Estimated power production series from a wind turbine park (WTP) are applied in a constructed model to study the possibilities appearing when including VSWTs in frequency support services. The income generated from including VSWTs in different regulation power market services is with the model compared against solely procuring the production capacity on the day ahead market. The studied frequency support services are then compared altogether to generate favorable solutions. The study examines both economic as well as technical features of the inclusion of VSWTs in frequency support services. Results found in the study were that inclusion of wind turbines for power regulation purposes could be seen as increasingly manageable and needed in the electric grid. The maturity of technical solutions alongwith a transition in the regulation power market could be observed as leading factors. The diversification of regulation abilities and the increasing economic incentives in the regulation power market was also found to be important reasons for including wind turbines in the regulation power market. In the study, it was also found thataggregating the power production from several VSWT could increase the ability to deliver the studied services. It was concluded that inclusion of VSWT in the frequency containment reserve during disturbed operation for down-regulation purposes as well as the fast frequency reserve was the most promising frequency support products for the inclusion of wind turbines. When including battery energy storages and to a larger part managing the durability demands for the services then the frequency contain reserve for normal operation and the frequency containment reserve for disturbed operation for upregulation purposes could be observed as preferable alternatives. Regulation abilities were concluded as achievable with the use of pitch and torque regulation techniques available in the variable speed wind turbine.
23
MACÊDO, Ana Vitória de Almeida. "Inclusão de energia eólica em sistemas elétricos e controle de frequência utilizando lógica Fuzzy." Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1549.
Full textAbstract:
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-08-24T14:29:39Z
No. of bitstreams: 1
ANA VITÓRIA DE ALMEIDA MACÊDO - TESE (PPgEE) 2017.pdf: 3449345 bytes, checksum: ff78e54595b43261343d5050a8dc3e50 (MD5)Made available in DSpace on 2018-08-24T14:29:39Z (GMT). No. of bitstreams: 1 ANA VITÓRIA DE ALMEIDA MACÊDO - TESE (PPgEE) 2017.pdf: 3449345 bytes, checksum: ff78e54595b43261343d5050a8dc3e50 (MD5) Previous issue date: 2017-03-29
CNPq
Um controle para auxílio do controle de frequência é projetado utilizando um método baseado em lógica fuzzy e no controle do ângulo de passo de turbinas eólicas de velocidade variável. O controle visa que as turbinas eólicas operem abaixo do seu valor nominal, estando sempre prontas para aumentar sua geração no caso de evento na rede elétrica, contribuindo para o controle de frequência. Com os esforços para converter tanta energia quanto seja possível com o vento disponível, a potência desperdiçada pela maioria dos controles estudados para elaboração desta tese vale a pena em relação aos benefícios do controle de frequência em sistemas com grande penetração das usinas eólicas, proporcionando a participação da energia eólica nos serviços ancilares. Ressaltando que a introdução de qualquer nova tecnologia de geração no sistema deve ser feita de modo que seja compatível com os princípios operacionais do sistema existente. O controle fuzzy de potência foi desenvolvido no Matlab®/Simulink e permite o bom funcionamento da turbina eólica utilizando uma metodologia alternativa aos controles clássicos. Com isto foi desenvolvido o controle de frequência também baseado em lógica fuzzy. Como grande vantagem do controle fuzzy destaca-se sua fácil adaptação a outros modelos de turbina que utilizem o controle de pitch (turbinas eólicas de velocidade variável), uma vez que o algoritmo é o mesmo, havendo a necessidade apenas de fazer testes para adaptação das faixas de operação do controle.
A control to support the frequency control is designed using a method based on fuzzy logic and pitch angle control in variable speed wind turbines. The control aims that some wind turbines operate below their rated value (derated or deloaded), being always ready to increase their generation in case of some event in the power grid, contributing to the frequency control. With efforts to convert as much energy as possible with the available wind, the power wasted by most controls studied in this work worth of the benefits of frequency control in systems with high power plants penetration, providing wind power to participate on ancillary services. Recalling that the introduction of any new generation technology into the system must be made in a way that is compatible with the operating principles of the existing system. The fuzzy control developed in Matlab®/Simulink for power control enables a suitable operation of the wind turbine using an alternative methodology to the classic controls, it was developed the frequency control also based on fuzzy logic. The fuzzy control great advantage highlight is its easy adaptation to other turbine design which use pitch control (variable speed wind turbines), since the algorithm is the same, just by doing tests for adjustment of the control operation ranges.
24
Guenoune, Ibrahim. "Commandes non linéaires robustes de systèmes éoliens." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0003/document.
Full textAbstract:
Le travail de cette thèse s’inscrit dans la commande non linéaire des structures éoliennes. Le premier objectif de cette thèse est la commande d’une éolienne standard fonctionnant à vitesse et angle de calage variables. Les stratégies de commande proposées permettant de commander l’éolienne dans des zones de fonctionnement différentes (optimisation et limitation de la puissance produite). Le deuxième objectif consiste en la conception de commande d’une nouvelle structure d’éolienne à double rotor. L’originalité de cette structure réside dans le fait qu’elle peut pivoter face au vent sans actionneur dédié, et ce grâce à la rotation libre du bras portant les deux éoliennes. Deux architectures de commande sont proposées afin d’orienter la structure face au vent : l’une crée un différentiel des angles de calage des pales des deux éoliennes, l’autre agissant via la différence de puissance produite par les deux génératrices. Étant donné que l’environnement est incertain et fortement perturbé (variations du vent, erreurs de modélisation, bruits de mesure), des lois de commande non linéaires robustes sont proposées. L’efficacité des stratégies de commande a été vérifiée selon différents scénariosThis work deals the nonlinear control of wind turbine structures. The first objective is the design of control laws of a standard wind turbine with variable speed-variable pitch angle. The proposed control strategies allow controlling the wind turbine indifferent operating areas (optimization and powerlimitation).The second objective consists in controlling a new structure of twin wind turbines. The originality of this structure lies in the fact that it can rotate face the wind without using a dedicated actuator, thanks to the free rotation of the arm carrying the wind turbines. Two control architectures are proposed in order to ensure the structure face the wind : pitch angles differential and the produced power difference. Given that the environment is uncertain (windvariations, modeling errors, noise), robust nonlinear control laws are proposed for a multiple objectives. The efficiency of the control strategies have been carried out according to several scenarios
25
Gaptia, Maï Moussa Lawan. "Gestion optimale d'énergie électrique à partir des sources d'énergies renouvelables dédiées aux sites isolés Power control for decentralized energy production system based on the renewable energies — using battery to compensate the wind/load/PV power fluctuations Three level Neutral-Point-Clamped Inverter Control Strategy using SVPWM for Multi-Source System Applications Wind turbine and Batteries with Variable Speed Diesel Generator for Micro-grid Applications." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMLH28.
Full textAbstract:
Les travaux de thèse s’inscrivent dans les problématiques des travaux de recherche de l’équipe thématique : Maitrise des Energies Renouvelables et systèmes de Stockage (MERS) du laboratoire GREAH-EA3220. Ils englobent le dimensionnement des éléments constitutifs du système et la gestion optimale de l’énergie électrique pour un système hybride (Diesel à vitesse variable, Eolien, PV et Batteries) dédié aux sites isolés. Les sources de production d'énergie alimentent des charges par le biais de convertisseurs multi-niveaux d’électronique de puissance. Le groupe électrogène comportant un moteur diesel à vitesse variable est considéré comme la principale source d’énergie utilisée pour contrôler la tension continue du point de couplage. Ce type de groupe électrogène est choisi pour optimiser la consommation du carburant. Il est sollicité pour délivrer une puissance électrique compatible avec le régime du moteur qui supporte mal les variations fréquentes et rapides. Les sources d’énergie renouvelables dont on cherche à augmenter la part d’énergie pour satisfaire la demande sont pilotées de manière à extraire instantanément le maximum de puissances disponible par les ressources (ensoleillement, vent). Celles-ci imposent ainsi leurs dynamiques et leurs intermittences au point de couplage. Le pack des batteries sert à compenser les fluctuations rapides de l’énergie provenant des sources d’énergie renouvelables par rapport à une évolution plus lente prise en charge par le groupe électrogène. La gestion des interactions au sein du système électrique hybride résultant est assurée au moyen de convertisseurs statiques multi-niveaux (AC / DC, DC / DC et DC / AC). Une approche de gestion d’énergie électrique fondée sur la répartition fréquentielle des perturbations induites au point de couplage par les sources renouvelables. Une plateforme expérimentale à échelle réduite (1/22) a été développée pour valider expérimentalement les approches théoriques et les simulations. Les résultats de simulations obtenus dans l’environnement logiciel Matlab/Simulink/SimPowerSystems et ceux issus du dispositif expérimental réalisé et piloté par dSPACE-1104 prouvent l’adéquation des méthodes de contrôle proposéesThe thesis works are part of the research work of the thematic team: Mastery of Renewable Energies and Storage Systems (MERS) of the GREAH-EA3220 laboratory. They include the dimensioning of the constituent elements of the system and the optimal management of electrical energy for a hybrid system (Variable speed Diesel, Wind, PV and Batteries) dedicated to isolated sites. Power sources supply loads through multi-level converters of power electronics. The generator set with a variable speed diesel engine is considered to be the main source of energy used to control the DC voltage at the coupling point. This type of generator is chosen to optimize fuel consumption. It is used to deliver an electrical power compatible with the engine speed which does not tolerate frequent and rapid variations. Renewable energy sources whose share of energy is sought to meet demand are managed so as to instantly extract the maximum power available from resources (sunshine, wind). These thus impose their dynamics and their intermittences at the coupling point. The battery pack is used to compensate for rapid fluctuations in energy from renewable energy sources compared to a slower evolution supported by the generator. Interactions within the resulting hybrid electrical system are managed by means of multi-level static converters (AC / DC, DC / DC and DC / AC). An electrical energy management approach based on the frequency distribution of disturbances induced at the coupling point by renewable sources. An experimental platform on a reduced scale (1/22) has been developed to experimentally validate theoretical approaches and simulations. The results of simulations obtained in the Matlab / Simulink / SimPowerSystems software environment and those from the experimental device produced and piloted by dSPACE-1104 prove the adequacy of the proposed control methods
26
Simley, Eric J. "Wind Speed Preview Measurement and Estimation for Feedforward Control of Wind Turbines." Thesis, University of Colorado at Boulder, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3721887.
Full textAbstract:
Wind turbines typically rely on feedback controllers to maximize power capture in below-rated conditions and regulate rotor speed during above-rated operation. However, measurements of the approaching wind provided by Light Detection and Ranging (lidar) can be used as part of a preview-based, or feedforward, control system in order to improve rotor speed regulation and reduce structural loads. But the effectiveness of preview-based control depends on how accurately lidar can measure the wind that will interact with the turbine.
In this thesis, lidar measurement error is determined using a statistical frequency-domain wind field model including wind evolution, or the change in turbulent wind speeds between the time they are measured and when they reach the turbine. Parameters of the National Renewable Energy Laboratory (NREL) 5-MW reference turbine model are used to determine measurement error for a hub-mounted circularly-scanning lidar scenario, based on commercially-available technology, designed to estimate rotor effective uniform and shear wind speed components. By combining the wind field model, lidar model, and turbine parameters, the optimal lidar scan radius and preview distance that yield the minimum mean square measurement error, as well as the resulting minimum achievable error, are found for a variety of wind conditions. With optimized scan scenarios, it is found that relatively low measurement error can be achieved, but the attainable measurement error largely depends on the wind conditions. In addition, the impact of the induction zone, the region upstream of the turbine where the approaching wind speeds are reduced, as well as turbine yaw error on measurement quality is analyzed.
In order to minimize the mean square measurement error, an optimal measurement prefilter is employed, which depends on statistics of the correlation between the preview measurements and the wind that interacts with the turbine. However, because the wind speeds encountered by the turbine are unknown, a Kalman filter-based wind speed estimator is developed that relies on turbine sensor outputs. Using simulated lidar measurements in conjunction with wind speed estimator outputs based on aeroelastic simulations of the NREL 5-MW turbine model, it is shown how the optimal prefilter can adapt to varying degrees of measurement quality.
27
Caliskan, Ahmet. "Constant Voltage, Constant Frequency Operation Of A Self-excited Induction Generator." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606678/index.pdf.
Full textAbstract:
In this thesis, control schemes for the self-excited induction generator are developed with Matlab/Simulink. Self-excited induction generator is considered as a constant voltage-constant frequency supply for an isolated load. A wind turbine is assumed to be the variable-speed drive of the induction generator. Control schemes aim to ensure a constant voltage-constant frequency operation of the induction generator in case of the variations in the wind speed and/or the load.
From the general model of the self-excited induction generator, the characteristics of the system and the dynamic responses of the system in case of any disturbance are
examined. Next, the control strategies are developed both for the squirrel-cage rotor induction generator and for the wound-rotor induction generator. Two control loops are necessary for constant voltage-constant frequency operation of a variable speed induction generator, one for the voltage regulation and the other for the frequency regulation. After developing the control loops, constant voltage-constant frequency
operation of the self-excited induction generator is simulated with a cage type saturation adaptive induction generator, a fixed capacitor with thyristor controlled reactor (TCR) used for frequency regulation and switched external resistors
connected to the stator terminals used for voltage regulation.
28
Poole, Sean. "The development of a segmented variable pitch small horizontal axis wind turbine with active pitch control." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020583.
Full textAbstract:
Small scale wind turbines operating in an urban environment produce dismal amounts of power when compared to their expected output [1-4]. This is largely due to the gusty wind conditions found in an urban environment, coupled with the fact that the wind turbines are not designed for these conditions. A new concept of a Segmented Variable Pitch (SVP) wind turbine has been proposed, which has a strong possibility to perform well in gusty and variable wind conditions. This dissertation explains the concept of a SVP wind turbine in more detail and shows analytical and experimental results relating to this concept. Also, the potential benefits of the proposed concept are mentioned. The results from this dissertation show that this concept has potential with promising results on possible turbine blade aerofoil configurations. Scaled model tests were completed and although further design optimisation is required, the tests showed good potential for the SVP concept. Lastly a proof-of-concept full scale model was manufactured and tested to prove scalability to full size from concept models. Along with the proof-of-concept full scale model, a wireless control system (to control the blade segments) was developed and tested.
29
Pawsey, N. C. K. Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Development and evaluation of passive variable-pitch vertical axis wind turbines." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2002. http://handle.unsw.edu.au/1959.4/18805.
Full textAbstract:
Vertical-axis wind turbines do not need to be oriented to the wind direction and offer direct rotary output to a ground-level load, making them particularly suitable for water pumping, heating, purification and aeration, as well as stand-alone electricity generation. The use of high-efficiency Darrieus turbines for such applications is virtually prohibited by their inherent inability to self-start. The provision of blade-articulation (variable-pitch blades) has been demonstrated by a number of researchers to make Darrieus turbines self-starting. One aim of this thesis is to evaluate the various concepts manifested in the numerous specific passive variable-pitch designs appearing in the literature, often without theoretical analysis. In the present work, two separate mathematical models have been produced to predict the performance of passive variable-pitch Darrieus-type turbines. A blade-element/momentum theory model has been used to investigate the relationships between the key parameter values and turbine steady-state performance. A strategy for parameter selection has been developed on the basis of these results. A free vortex wake model for passive variable-pitch turbines has been developed, allowing the study of unsteady performance. Significant reduction of average ef- ficiency in a turbulent wind is predicted for a Darrieus turbine. The improved low-speed torque of passive variable-pitch turbines is predicted to significantly improve turbulent wind performance. Two new design concepts for passive variable-pitch turbines are presented that are intended to allow greater control of blade pitch behaviour and improved turbulent wind performance. A prototype turbine featuring these design concepts has been designed, constructed and tested in the wind tunnel. As part of this testing, a technique has been developed for measuring the pitch angle response of one of the turbine blades in operation. This allows comparison of predicted and measured pitch histories and gives insight into the performance of turbines of this type. Results have demonstrated the usefulness of the mathematical models as design tools and have indicated the potential of one of the new design concepts in particular to make a vertical axis wind turbine self-starting.
30
Feytout, Benjamin. "Commande crone appliquée à l'optimisation de la production d'une éolienne." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2014BOR14946/document.
Full textAbstract:
Les études, menées en collaboration entre la société VALEOL et le laboratoire IMS, proposent des solutions pour optimiser la production et le fonctionnement d'une éolienne. Il s’agit de travailler sur les lois de commande du système ou des sous-systèmes en utilisant la commande CRONE, répondant à un besoin de robustesse. Chaque étude met en avant des aspects de modélisation, d’identification et de synthèse de lois de commande avant mises en application au travers de simulations ou d’essais sur modèles réduits et taille réelle.Le chapitre 1 donne une vision d’ensemble des problématiques traitées dans ce manuscrit, à l’aide d’états de l’art et de remise dans le contexte économique et industriel de 2013.Le chapitre 2 introduit la commande CRONE pour la synthèse de régulateurs robustes. Cette méthodologie est utilisée pour réaliser l’asservissement de la vitesse de rotation d’une éolienne à vitesse variable, présentant une architecture innovante avec un variateur de vitesse mécanique et génératrice synchrone.Le chapitre 3 établit la comparaison de trois nouveaux critères d’optimisation pour la méthodologie CRONE. Le but est de réduire sa complexité et de faciliter sa manipulation par tout utilisateur. Les résultats sur les différents critères sont obtenus par simulations sur un exemple académique, puis sur un modèle d’éolienne de type MADA.Le chapitre 4 porte sur la réduction des charges structurelles transmises par le vent à l’éolienne. Il est question d’une amélioration du contrôle de l’angle de pitch par action indépendante sur chaque pale en fonction de la position du rotor ou encore des perturbations liées au ventLe chapitre 5 est consacré à la conception d’un système d’antigivrage et dégivrage d’une pale dans le cadre d’un projet Aquitain. Après modélisation et identification du procédé, la commande CRONE est utilisée pour réguler la température d’une peinture polymère chauffante sous alimentation électrique disposée sur les pales. L’étude est complétée par la mise en place d’un observateur pour la détection de présence de givreThe research studies, in collaboration with VALEOL and IMS laboratory, propose several solutions to optimize the production and the efficiency of a wind turbine. The general theme of the work is based on control laws of the system or subsystems using the CRONE robust design. Each part highlights aspects of modeling, system identification and design before simulations or tests of scale and full size models. Chapter 1 provides an overview of the issues discussed in this manuscript, using states of the art and precisions on the industrial and economic context of 2013.Chapter 2 introduces the CRONE command for robust design. It is used to achieve the control of the rotation speed of a variable speed wind turbine, with an innovative architecture - mechanical variable speed solution and synchronous generator.Chapter 3 makes a comparison of three new optimization criteria for CRONE design. The aim is to reduce the methodology complexity and to facilitate handling by any user. The results are obtained through simulations on an academic example, then with a DFIG wind turbine model. Chapter 4 focuses on the reduction of structural loads transmitted by the wind on the turbine. It is about better control of the pitch angle by individual pitch control, depending on the rotor position or wind disturbances.Chapter 5 deals with the design of an anti-icing/de-icing system for blades. After the modeling and identification steps, the CRONE design is used to control the temperature of a heating coating disposed on the blades. An observer is finally designed to detect the presence of ice
31
Dler, Dler Kamiran. "STUDYING THE STABILITY OF FIXED SPEED WIND TURBINES BY DETERMINING THE CRITICAL ROTOR SPEED." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/569.
Full textAbstract:
The stability of fixed-speed wind turbines in case of fault happening in the grid is studied in this thesis by determining the critical rotor speed. Fixed-speed wind turbines are subjected to various types of fault when they are connected directly to grid [3]. In this study, the critical rotor speed is the maximum speed that the rotor of the wind turbine can reach before the wind turbine loses its stability. The factors that can affect the critical rotor speed are investigated such as the generator parameters, the duration of the fault, the parameters of the grid, and the type of the fault. Simulation studies are carried out in this thesis. The results of the simulation studies show the effect of the factors mentioned above on the stability of fixed-speed wind turbines. The results also show that the time of the fault duration varies with the type of the fault; therefore, designing a protection unit by observing the rotor speed of the rotor during the fault is more suitable that designing a control unit depending on the fault duration.
32
Sangpanich, Umarin. "Optimization of wind-solar energy systems using low wind speed turbines to improve rural electrification." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=18944.
Full textAbstract:
Electricity is significant in improving the quality of life for people in rural and remote areas in developing countries. There are two main options for Rural Electrification (RE), namely grid extension and stand-alone systems. The governments and developers face the challenges of their limitations, namely technical, economic and environmental effects of each RE choice. This thesis intends to improve RE by focusing on renewable energy technologies, namely Wind Turbine (WT) and Photovoltaic (PV) systems. They have been developed and applied to RE because they are simple and environmentally friendly. They can be installed as separate units and they are sustainable alternative energy solutions. Installation, cost and performance are crucial issues of WT and PV applications, and are based on the terrain and climate where the renewable are installed. The efficiency of WTs and PV modules has increased, while their cost has declined continuously. However, a PV system still has installatio n costs around two times more expensive per watt than WTs. Most WTs using current technology can be financially worthwhile for high wind speed areas, having wind speeds greater than 6.4 m/s at 10 m hub height, but most rural areas have wind speeds of less than 6 m/s at the same height. Therefore, Low Wind Speed Turbines (LWSTs) have evolved, by increasing rotor diameter and while maintaining similar generator capacity. This is to reduce Levelized Cost of Energy (LCOE) for WTs in low wind speed areas. This thesis proposes simple cost models, namely the Sum-component cost model and the Total-cost model in order to calculate the LCOE of LWSTs. In addition, novel aspects of this thesis are that the optimization processes of stand-alone hybrid WT-PV systems and hybrid WT-PV systems using batteries at peak demand in remote area power systems provide simple, fast and flexible methods, by applying Multi-objective Evolutionary Algorithm (MOEA). The MOEA can analyze complex objective problems a nd provide an accurate multi-objective method. Results from relevant case studies show that the cost models and the optimization processes proposed are novel and are valuable tools for analysis and design, including the approaches for improving the system reliability and for estimating the Initial Capital Cost (ICC) of WTs having different rated wind speeds. The proposed algorithms are generic and can be utilized for other energy planning problems.
33
Ndzukuma, Sibusiso. "Statistical tools for wind energy generation." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1020627.
Full textAbstract:
In this study we conduct wind resource assessment to evaluate the annual energy production of a wind turbine. To estimate energy production of a wind turbine over a period of time, the power characteristics of the wind turbine are integrated with the probabilities of the wind speed expected at a chosen site. The first data set was obtained from a wind farm in Denmark. We propose several probability density functions to model the distribution of the wind speed. We use techniques from nonlinear regression analysis to model the power curve of a wind turbine. The best fit distribution model is assessed by performing numeric goodness–of–fit measures and graphical analyses. Johnson’s bounded (SB) distribution provides the best fit model with the smallest Kolmogorov–Smirnov (K-S) test statistic . 15. The four parameter logistic nonlinear regression (4PL) model is determined to provide the best fit to the power curve data, according to the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). The estimated annual energy yield is compared to the actual production of the wind turbine. Our models underestimate the actual energy production by a 1 difference. In Chapter Six we conduct data processing, analyses and comparison of wind speed distributions using a data set obtained from a measuring wind mast mounted in Humansdorp, Eastern Cape. The expected annual energy production is estimated by using the certified power curve as provided by the manufacturer of the wind turbine under study. The commonly used Weibull distribution is determined to provide the best fit distribution model to our selected models. The annual energy yield is estimated at 7.33 GWh, with a capacity factor of 41.8 percent.
34
Stott, Paul Anthony. "Renewable variable speed hybrid system." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4781.
Full textAbstract:
At present many remote and Island communities rely solely on diesel powered generators to provide electricity. Diesel fuel is both expensive and polluting and the constant speed operation of the diesel engine is inefficient. In this thesis the use of renewable energy sources to help offset diesel fuel usage and an alternative way of running the diesel generator with the aim of reducing electrical energy costs is investigated. Diesel generators have to be sized to meet peak demand, in one or two diesel generator island grids, these generators will be running at a fraction of maximum output for most of the time. A new variable speed diesel generator allows for a reduction in fuel consumption at part load compared to constant speed operation. Combining the variable speed diesel generator with renewable generation should maximise the diesel fuel offsetting of the renewable source due to the increased efficiency at low loads. The stability issues of maintaining transient performance in a renewable variable speed hybrid system have been modelled and simulated. A control strategy has been developed and the use of energy storage as a buffer for any remaining stability problems has been explored. The control strategy has then been experimentally tested along with one of the possible energy storage solutions. An economic feasibility study has been performed on a case study community to validate the main aim of this research of reducing the cost of electrical energy in diesel generator grids.
35
Burnham, David James. "Control of wind turbine output power via a variable rotor resistance." Thesis, [Austin, Tex. : University of Texas, 2009. http://hdl.handle.net/2152/ETD-UT-2009-05-105.
Full text
36
Ross, Ian Jonathan. "Wind Tunnel Blockage Corrections: An Application to Vertical-Axis Wind Turbines." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1271306622.
Full text
37
Pietrangeli, Sven. "Comparison of fixed diameter and variable diameter wind turbines driving a permanent magnet hub motor." Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/1283.
Full textAbstract:
Thesis submitted in fulfilment of the requirements for the degree
MAGISTER TECHNOLOGIAE: Mechanical Engineering
in the
FACULTY OF ENGINEERING
at the
CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2012The amount of power a horizontal axis wind turbine (HAWT) can produce is determined by two main factors, wind velocity and rotor swept area. Theory dictates that the power production of a horizontal wind turbine is related to the cube of wind velocity and the square of the turbine diameter (or radius). The power produced at any given time is thus dependent on of the wind velocity and the rotor swept area of the turbine. Wind is variable in availability and consistency. Very little can be done to effect the wind velocity passing through the turbine rotor area and its effect is minimal. Thus understandably if more power is required, from the same wind velocity, the rotor diameter must be increased. A variable length blade can adapt lengthwise to accommodate low wind velocities and similarly high wind velocities during extreme conditions, thus increasing the operational time and power production of the turbine. The work undertaken in this thesis is a comparative study between standard design, fixed length blades to that of a modified design, variable length blade. The project entailed the design and development of small diameter HAWT blades and experimental testing. The turbine blades were designed using applicable theory and manufactured from available materials. For the experiments, the turbine was mounted on a vehicle and driven at various speeds. Due to size limitations, no dynamic adaption was done during testing. The variable length design blade was obtained by cutting increments off. The results obtained from each test were compared at corresponding points and conditions. Final interpretation of results lead to the conclusion that by increasing or decreasing the turbine blade length the area of turbine energy capture can be adjusted to affect the amount of power produced. Additional benefits included, force reduction during extreme operating conditions, extended production period for the turbine and a mechanical start up method during low wind speeds. The financial feasibility did not form part of the scope of this thesis and the technical feasibility of the concept can be thoroughly addressed in future research.
38
Benjanirat, Sarun. "Computational studies of the horizontal axis wind turbines in high wind speed condition using advanced turbulence models." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-08222006-145334/.
Full textAbstract:
Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2007.Samual V. Shelton, Committee Member ; P.K. Yeung, Committee Member ; Lakshmi N. Sankar, Committee Chair ; Stephen Ruffin, Committee Member ; Marilyn Smith, Committee Member.
39
Dib, Tamara S. "Relationship between Anisotropy and Dispersive Stress in Wind Plants with Variable Spacing." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4335.
Full textAbstract:
Large eddy simulations are considered for wind plants with varied spanwise and streamwise spacing. Data from five different configurations of staggered and aligned LES wind turbine arrays with a neutrally stratified atmospheric boundary layer are employed for analysis. Fields are analyzed by evaluating the anisotropy stress invariants based on the Reynolds shear stresses and dispersive stress tensor. The relationship between quantities are drawn as a function of the wind plant packing. Reynolds stresses and dispersive stresses are investigated alongside a domain altered version of the second and third scalar invariants, ξ, η, as well as the combination of the two invariants described by the function F = 1−27η 2 + 54ξ 3. F is a measure of the approach to either a two-component turbulence (F=1) or an isotropic turbulence (F=0). The invariant η describes the degree of anisotropy while ξ describes the characteristic shape. For the purposes of this study, the LES data is analyzed to understand the effects of canopy density on anisotropy and dispersive stresses, adding further insight and detail for future modeling techniques.
40
Faley, Katherine A. "Control System Design for Offshore Wind Turbines Under Extreme Icy/Tide-Variable Weather Conditions." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1321990494.
Full text
41
Kjellin, Jon. "Vertical Axis Wind Turbines : Electrical System and Experimental Results." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182438.
Full textAbstract:
The wind power research at the division of Electricity at Uppsala University is aimed towards increased understanding of vertical axis wind turbines. The considered type of wind turbine is an H-rotor with a directly driven synchronous generator operating at variable speed. The experimental work presented in this thesis comprises investigation of three vertical axis wind turbines of different design and size. The electrical, control and measurement systems for the first 12 kW wind turbine have been designed and implemented. The second was a 10 kW wind turbine adapted to a telecom application. Both the 12 kW and the 10 kW were operated against dump loads. The third turbine was a 200 kW grid-connected wind turbine, where control and measurement systems have been implemented. Experimental results have shown that an all-electric control, substituting mechanical systems such as blade-pitch, is possible for this type of turbine. By controlling the rectified generator voltage, the rotational speed of the turbine is also controlled. An electrical start-up system has been built and verified. The power coefficient has been measured and the stall behaviour of this type of turbine has been examined. An optimum tip speed ratio control has been implemented and tested, with promising results. Use of the turbine to estimate the wind speed has been demonstrated. This has been used to get a faster regulation of the turbine compared to if an anemometer had been used.
42
Aguilar, Milton Ernesto Barrios. "Sintonia dos controladores para aerogeradores de velocidade variável com geradores de indução de dupla alimentação utilizando um algoritmo meta-heurístico de inteligência coletiva." Universidade Estadual do Oeste do Parana, 2016. http://tede.unioeste.br:8080/tede/handle/tede/1036.
Full textAbstract:
Made available in DSpace on 2017-07-10T16:41:35Z (GMT). No. of bitstreams: 1
Dissert Milton Ernesto Barrios Aguilar 3.pdf: 9539969 bytes, checksum: 3ccd249e45fb24533b33236925ee74dc (MD5)
Previous issue date: 2016-08-04Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The increase in wind power integration into power systems is currently a general trend in many countries and the Variable-Speed Wind Turbine (VSWT) Equipped with a Doubly Fed Induction Generator System with back-to-back power converters are most often used for this purpose. There is the need for its control system to operate properly to ensure stability and to achieve the desired performance when they are subjected to different transient disturbances, which is a difficult taste due to nonlinearities and strong coupling between electrical and mechanical variables in this type of wind turbine. In this context, this work aims to tune the gains of the PI controllers that make up the control system using a collective intelligence meta-heuristic algorithm for two normal perturbations in the operation of a wind farm: a wind variation and electrical fault. For that, it was modeled the wind turbine taking advantage of detailed modeling, considering the stator voltage oriented control structure, with active and reactive power control loops and their respective current controls, all equipped with PI controllers. Therefore, a set of objective functions was generated penalizing the most important variables directly from the dynamic simulation. Next, a multi-objective PSO algorithm has been enhanced, to be used as a tuning tool. Then the algorithm was applied to the VSWT for Single-machine infinite bus system for wind speed variation and electrical fault. Finally, the robustness of the tunings was tested on the in Single-machine infinite bus system and a 32 nodes feeder. The PSO showed good ability to exploitation and intensification of the search space reaching the preset tuning requirements in all cases. Stability and satisfactory performance results were obtained for transient disturbances thanks to key variables penalty in the objective functions. The tuning resulted robust enough for variations of feeder parameters and operating conditions besides the proper stiffness coefficient of the turbine generator mechanical coupling, whenever the wind turbine was subjected to disturbances considered in the tuning. It is also noted that exploring the objective functions and the algorithm itself can attain a large improvement in the performance of the tuned wind turbine control system for wind variations and electrical faults
O aumento da integração da geração eólica em sistemas elétricos de potência é atualmente uma tendência generalizada em muitos países e os Aerogeradores de Velocidade Variáveis (AVV) com Geradores de Indução de Dupla Alimentação (DFIG) com conversores de potência de tipo back-to-back são os mais empregados para este fim. Existe a necessidade de que seu sistema de controle atue corretamente para garantir a estabilidade e obter o desempenho desejado quando estes são submetidos a diferentes perturbações transitórias, o que resulta difícil devido às não-linearidades e à forte relação entre as grandezas elétricas e mecânicas deste tipo de aerogerador. Neste contexto, esta dissertação tem como objetivo a sintonia dos ganhos dos controladores PI que compõem o sistema de controle, utilizando um algoritmo meta-heurístico de inteligência coletiva, para duas perturbações normais na operação de uma usina eólica: variação de vento e falta elétrica. Para isso, foi modelado o DFIG aproveitando modelos detalhados, considerando a estrutura de controle orientada pela tensão do estator, com malhas de controle de potência ativa e reativa e seus respetivos controles de correntes, todas equipadas com controladores tipo PI. Logo foi gerado um conjunto de funções objetivos, penalizando diretamente das simulação dinâmica as variáveis de maior importância. A seguir, foi aprimorado um algoritmo PSO multi-objetivo, o qual é utilizado como ferramenta de sintonia. Em seguida, o algoritmo foi aplicado ao DFIG na configuração máquina barra-infinita para variação de vento e falta elétrica. Finalmente foi testada a robustez das sintonias obtidas no sistema de máquina barra-infinita e em um alimentador de 32 nós. O PSO apresentou uma boa capacidade de exploração e intensificação do espaço de busca alcançando os requisitos de sintonia preestabelecidos em todos os casos. Os resultados de estabilidade e desempenhos foram satisfatórios para as perturbações transitórias utilizadas graças à penalização de variáveis chaves nas funções objetivos. A sintonia resultou suficientemente robusta para variações de parâmetros do alimentador e de condições operativas, além do próprio coeficiente de rigidez do acoplamento mecânico turbina-gerador, sempre que a usina esteja submetida a perturbações consideradas na sintonia. Observa-se também que explorando as funções objetivo e o próprio algoritmo pode-se atingir uma ampla melhoria no desempenho do sistema de controle do DFIG sintonizado para as variações de vento e faltas elétricas. Palavras-chave: Geração Eólica, Aerogeradores
43
Weiss, Austin M. "REMOVING VEHICLE SPEED FROM APPARENT WIND VELOCITY." UKnowledge, 2019. https://uknowledge.uky.edu/bae_etds/67.
Full textAbstract:
Variable-rate technologies for sprayer applications stand to increase efficacy by ensuring the right amount of chemical is applied at the right location. However, external environmental factors such as droplet drift caused by variable ambient condition, are not yet integrated into modern sprayer systems. Real-time wind velocity measurements can be used to control droplet spectra for reducing spray drift by actuating a variable-orifice nozzle. This work aimed to develop data processing methods needed to filter noise and remove vehicle speed from wind velocity measurements collected with an ultrasonic anemometer aboard a moving platform. Using a global navigation satellite system (GNSS), vehicle speed was calculated in the field and subtracted from apparent wind velocity for comparison to static measurements. Experiments under stationary and dynamic sensor deployments were used to develop an algorithm to provide instantaneous local wind velocity and to better understand the local spatiotemporal variability of wind under field conditions.
44
Alkan, Deniz. "Investigating CVT as a Transmission System Option for Wind Turbines." Thesis, KTH, Energiteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121187.
Full textAbstract:
In this study, an innovative solution is examined for transmission problems and frequency control for wind Turbines. Power electronics and the gear boxes are the parts which are responsible of a significant amount of failures and they are increasing the operation and maintenance cost of wind turbines. Continuously transmission (CVT) systems are investigated as an alternative for conventional gear box technologies for wind turbines in terms of frequency control and power production efficiency. Even though, it has being used in the car industry and is proven to be efficient, there are very limited amount of studies on the CVT implementation on wind turbines. Therefore, this study has also an assertion on being a useful mechanical analyse on that topic. After observing several different types of possibly suitable CVT systems for wind turbines; a blade element momentum code is written in order to calculate the torque, rotational speed and power production values of a wind turbine by using aerodynamic blade properties. Following to this, a dynamic model is created by using the values founded by the help of the blade element momentum theory code, for the wind turbine drive train both including and excluding the CVT system. Comparison of these two dynamic models is done, and possible advantages and disadvantages of using CVT systems for wind turbines are highlighted. The wind speed values, which are simulated according to measured wind speed data, are used in order to create the dynamic models, and Matlab is chosen as the software environment for modelling and calculation processes. Promising results are taken out of the simulations for both in terms of energy efficiency and frequency control. The wind turbine model, which is using the CVT system, is observed to have slightly higher energy production and more importantly, no need for power electronics for frequency control. As an outcome of this study, it is possible to say that the CVT system is a candidate of being a research topic for future developments of the wind turbine technology.
45
Den, Heijer Francois Malan. "Development of an active pitch control system for wind turbines / F.M. den Heijer." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2635.
Full textAbstract:
A wind turbine needs to be controlled to ensure its safe and optimal operation, especially during high wind speeds. The most common control objectives are to limit the power and rotational speed of the wind turbine by using pitch control.
Aero Energy is a company based in Potchefstroom, South Africa, that has been developing and manufacturing wind turbine blades since 2000. Their most popular product is the AE1kW
blades. The blades have a tendency to over-speed in high wind speeds and the cut-in wind speed must be improved. The objective of this study was to develop an active pitch control system for wind turbines. A prototype active pitch control system had to be developed for the AE1kW blades. The objectives of the control system are to protect the wind turbine from over-speeding and to improve start-up performance.
An accurate model was firstly developed to predict a wind turbine’s performance with active
pitch control. The active pitch control was implemented by means of a two-stage centrifugal
governor. The governor uses negative or stalling pitch control. The first linear stage uses a soft spring to provide improved start-up performance. The second non-linear stage uses a hard spring to provide over-speed protection. The governor was manufactured and then tested with the AE1kW blades. The governor achieved both the control objectives of over-speed protection and improved start-up performance. The models were validated by the results.
It was established that the two-stage centrifugal governor concept can be implemented on any
wind turbine, provided the blades and tower are strong enough to handle the thrust forces
associated with negative pitch control. It was recommended that an active pitch control system be developed that uses positive pitching for the over-speed protection, which will eliminate the large thrust forces. Keywords: pitch control, wind turbine, centrifugal governor, over-speed protection, cut-in wind speed, blade element-momentum theory, rotor, generator, stall, feathering.Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2009.
46
EL, Itani Samer. "Short-term frequency support utilizing inertial response of variable-speed wind plants." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104853.
Full textAbstract:
In regions with increasing penetration of variable-speed wind generators, grid operators are concerned about frequency security as system inertia is decreasing. The partial replacement of conventional plants with modern wind plants may cause system frequency regulation to fall below acceptable levels, especially in isolated power systems. This study investigates the contribution of variable-speed wind generators to short-term frequency support. This contribution is obtained by transiently releasing part of the stored kinetic energy in the turbine blades, namely the inertial response. Some inertial response schemes have been researched to be incorporated as auxiliary loops in the controllers of wind generators. First, we compare the performance of these earlier implementations and identify their shortcomings. Then, we quantify the extractable inertial power from a modern wind turbine, given its power characteristic, equivalent inertia, and prevailing wind condition. From this understanding, a new controller, based on the asynchronous release of kinetic energy, is proposed to achieve a superior, more controllable performance. The controller is composed of a 'detection and triggering' scheme that detects the frequency event, a 'power shaping' function that decides the duration and amount of inertial power released, and a 'rotor speed recovery' scheme that brings the turbine back to its optimal speed which corresponds to maximum power tracking. Time-domain simulations were performed to examine the performance of this controller. Based on its impact on system frequency and wind farm operation, the new controller was compared to earlier implementations of wind plant inertial response. The results show that the proposed controller is capable of bringing together the advantages of the different earlier implementations for better grid integration of wind turbine generators. Its effectiveness in reducing the initial frequency fall after a load-generation mismatch promises significant contribution to system inertia. Its controllable, predictable nature is a distinct advantage that enables grid operators to understand, forecast and quantify the impact of incorporating this controller into grid-connected wind generators.Dans les régions à forte pénétration d'éoliennes à vitesse variable, les opérateurs de réseau sont concernés par la sécurité de la fréquence lorsque l'inertie du système décroît. La substitution partielle d'usines conventionnelles par des usines éoliennes modernes pourrait causer le réglage de la fréquence du système à chuter sous des niveaux acceptables, surtout dans le cas de systèmes d'alimentation isolés. Cette étude se penche sur comment les éoliennes à vitesse variable peuvent contribuer au support de la fréquence à court terme. Cette contribution est obtenue grâce au relâchement transitoire d'une partie de l'énergie cinétique contenue dans les aubes de turbine, plus spécifiquement la réponse transitoire. Quelque programmes de réponse inertielle ont été étudiés afin d'être incorporés comme boucle auxiliaire dans les contrôles des génératrices à vent. En premier lieu, on compare la performance d'implémentations préexistantes entre-elles afin d'en identifier les défauts respectifs. En second lieu, on quantifie la puissance inertielle capable d'être extraite d'une génératrice à vent moderne tout en prenant en considération les caractéristiques de puissance, son inertie équivalente ainsi que les conditions de vent dominantes. Avec cette notion, un nouveau régulateur qui est basé sur un relâchement non-synchronisé d'énergie cinétique est proposé afin d'obtenir une performance supérieure et plus contrôlable. Le contrôleur est composé d'un programme de «détection et déclenchement» qui détecte la variation de la fréquence, d'une fonction «formatrice de puissance» qui calcule la durée ainsi que la quantité de puissance cinétique relâchée, et d'un programme de «récupération de vitesse du rotor» qui ramène la turbine à sa vitesse optimale qui correspond au suivi de la vitesse maximale. Des simulations dans le domaine du temps ont été effectuées afin d'examiner la performance du régulateur. À partir de son impact sur la fréquence du système et l'opération de plants éolien, le nouveau contrôleur a été comparé aux implémentations antérieures de réponse inertielle d'usines de vent. Les résultats démontrent que le contrôleur proposé est capable d'unifier les avantages des implémentations précédentes afin d'avoir une meilleure intégration des éoliennes. Sa capacité de réduire la chute de fréquence initiale qui suit un décalage au niveau de la génération de charge promet une contribution significative sur l'inertie du système. En fait, sa nature contrôlable et prévisible lui donne un avantage distinct qui permet aux opérateurs de réseau de pouvoir comprendre, prédire et quantifier l'impact potentiel de l'implémentation de ce régulateur dans des génératrices à vent connectées au réseau.
47
Wise, John Nathaniel. "Optimization of a low speed wind turbine using support vector regression." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2737.
Full textAbstract:
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009.NUMERICAL design optimization provides a powerful tool that assists designers in improving their products. Design optimization automatically modifies important design parameters to obtain the best product that satisfies all the design requirements. This thesis explores the use of Support Vector Regression (SVR) and demonstrates its usefulness in the numerical optimization of a low-speed wind turbine for the power coe cient, Cp. The optimization design problem is the three-dimensional optimization of a wind turbine blade by making use of four two-dimensional radial stations. The candidate airfoils at these stations are selected from the 4-digit NACA range. A metamodel of the lift and drag coe cients of the NACA 4-digit series is created with SVR by using training points evaluated with XFOIL software. These SVR approximations are used in conjunction with the Blade Element Momentum theory to calculate and optimize the Cp value for the entire blade. The high accuracy attained with the SVR metamodels makes it a viable alternative to using XFOIL directly, as it has the advantages of being faster and easier to couple with the optimizer. The technique developed allows the optimization procedure the freedom to select profiles, angles of attack and chord length from the 4-digit NACA series to find an optimal Cp value. As a result of every radial blade station consisting of a NACA 4-digit series, the same lift and drag metamodels are used for each station. This technique also makes it simple to evaluate the entire blade as one set of design variables. The thesis contains a detailed description of the design and optimization problem, the implementation of the SVR algorithm, the creation of the lift and drag metamodels with SVR and an alternative methodology, the BEM theory and a summary of the results.
48
Tsang, Ho-on Frederick, and 曾可安. "Time variable parameter estimation on the wind speed air quality modelin Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31253283.
Full text
49
Medin, Christian. "Gross Annual Energy Production for Wind Turbines in Sweden as a Function of Wind Speed from the MIUU Mesoscale Atmospheric Model." Thesis, Uppsala universitet, Matematiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-221854.
Full textAbstract:
In this thesis I find a function for how Gross Annual Energy Production per square meter of rotor area depends on wind data from the MIUU Mesoscale Atmospheric Model. The result can be used in the early stages of the process of finding a suitable site for a new wind farm. The relationship is found by looking at 325 wind turbines in Sweden and calculating the GAEP/m2 and plotting it against the wind speed given by MIUU. The final function is given by a linear regression and is stated in the equation below: GAEP/m2 = -576.96 + 209.18*MIUU Wind farm producers will be able to get a estimate of the GAEP by using the equation and the easily available data from the MIUU-model and can then make a shortlist of possible locations for the new turbines.
50
Harman, John E. "Feasibility and optimum design study of a low speed wind turbine rotor system for underground communication power." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5688.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains ix, 85 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 58-59).