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- Title
- THE SIMULATION AND CONTROL OF A GRID-CONNECTED WIND ENERGY CONVERSION SYSTEM.
- Creator
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McCartney, Shauna, Yuan, Jiann S., University of Central Florida
- Abstract / Description
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With the rising cost of petroleum, concerns about exhausting the fossil fuels we depend on for energy, and the subsequent impacts that the burning of these types of fuels have on our environment, countries around the world are paying close attention to the development of renewable types of energy. Consequently, researchers have been trying to develop ways to take advantage of different types of clean and renewable energy sources. Wind energy production, in particular, has been growing at an...
Show moreWith the rising cost of petroleum, concerns about exhausting the fossil fuels we depend on for energy, and the subsequent impacts that the burning of these types of fuels have on our environment, countries around the world are paying close attention to the development of renewable types of energy. Consequently, researchers have been trying to develop ways to take advantage of different types of clean and renewable energy sources. Wind energy production, in particular, has been growing at an increasingly rapid rate, and will continue to do so in the future. In fact, it has become an integral part in supplying our future energy needs, making further advancements in the field exceedingly critical. A 2 MW wind energy conversion system (WECS) is presented and has been simulated via the dynamic simulation software Simulink. This WECS consists of a 2 MW permanent magnet synchronous generator connected to the transmission grid through a power conversion scheme. The topology of this converter system consists of a passive AC/DC rectifier as well as a PWM DC/AC IGBT inverter, used to interface the DC link with the grid. The inverter has an integrated current control system for power factor correction to improve output power stability. The described WECS enhances grid-side tolerance by buffering wind power disturbances demonstrated by its capability to isolate the grid from wind speed fluctuations. It also optimizes wind energy capture through harmonic filtering, enhancing output power quality. These findings have the potential to lead to further advancements including the capability for island operation and integration to a smart grid.
Show less - Date Issued
- 2010
- Identifier
- CFE0003484, ucf:48972
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003484
- Title
- An Introductory Study of The Dynamics of Autorotation for Wind Energy Harvesting.
- Creator
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Salih, Bilal, Das, Tuhin, Kassab, Alain, Kauffman, Jeffrey, University of Central Florida
- Abstract / Description
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Wind turbines have been used for decades to harvest wind energy. They are suitable only to work on close to ground, and have several drawbacks that are related to the availability of the wind and the amount of extracted power compared with the cost of construction. On the other hand, there is an abundant wind power that is available at high altitudes. The wind jet streams at high elevations 8 ? 12 kms are pervasive and persistent, and can potentially produce immense wind energy. Even at...
Show moreWind turbines have been used for decades to harvest wind energy. They are suitable only to work on close to ground, and have several drawbacks that are related to the availability of the wind and the amount of extracted power compared with the cost of construction. On the other hand, there is an abundant wind power that is available at high altitudes. The wind jet streams at high elevations 8 ? 12 kms are pervasive and persistent, and can potentially produce immense wind energy. Even at moderate elevations of 4 ? 5 kms, wind power densities are much higher than on ground and more consistent. Consequently, in this thesis research, we investigate the topic of harvesting energy from high altitudes. First, we provide a comprehensive review of two existing theoretical methods that are proposed for airborne wind energy harvesting, the tethered airfoil, and the static autogyro. The latter approach has inherent advantages that warrant further investigation. Autorotation is a well-known phenomenon where a rotor sustains its angular velocity and maintains significant lift in the presence of strong aerodynamic forces and torques generated by interaction with a strong wind field. Autorotation has been researched in the context of free descent of helicopters but has not been considered for energy harvesting. Existing models have mainly focused on statics analysis. In this research, we propose a simple dynamic model of the Autogyro, with the goal of ultimately realizing an Autorotation Energy System (AES). The focus of our work is to provide a preliminary dynamic analysis of autorotation, which is largely absent in current literature, to explore the possibility of using autorotation for designing a multipurpose system that can simultaneously fly at high altitudes and generate energy from the wind. The proposed preliminary dynamic model is used to generate a simulation platform, which is used to explore the autogyros rudimentary maneuvers. Extensive simulation results are provided to evaluate the dynamic performance of AES. Energy harvesting analyses and results are also presented. It is expected that the results will guide the choice of actuations and control that will be necessary for generating combined autorotation and powered flights that would be net energy generating or energy efficient. The research will be relevant for both tethered and untethered AES and could also be incorporated into multi-rotor based UAVs such as quadrotors.
Show less - Date Issued
- 2014
- Identifier
- CFE0005245, ucf:50597
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005245
- Title
- SMALL-SCALE HYBRID ALTERNATIVE ENERGY MAXIMIZER FOR WIND TURBINES AND PHOTOVOLTAIC PANELS.
- Creator
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Kerley, Ross, Batarseh, Issa, University of Central Florida
- Abstract / Description
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This thesis describes the creation of a small-scale Hybrid Power System (HPS) that maximizes energy from a wind turbine and photovoltaic array. Small-scale HPS are becoming an increasingly viable energy solution as fossil fuel prices rise and more electricity is needed in remote areas. Modern HPS typically employ wind speed sensors and three power stages to extract maximum power. Modern systems also use passive rectifiers to convert AC from the wind turbine to DC that is usable by power...
Show moreThis thesis describes the creation of a small-scale Hybrid Power System (HPS) that maximizes energy from a wind turbine and photovoltaic array. Small-scale HPS are becoming an increasingly viable energy solution as fossil fuel prices rise and more electricity is needed in remote areas. Modern HPS typically employ wind speed sensors and three power stages to extract maximum power. Modern systems also use passive rectifiers to convert AC from the wind turbine to DC that is usable by power electronics. This passive system inefficiently wastes power and introduces damaging harmonic noise to the wind turbine. The HPS described in this thesis does not require external wind speed sensors, and has independent wind and solar Maximum Power Point Tracking (MPPT). It converts AC from the wind turbine to DC with a Vienna rectifier that can be controlled to improve efficiency, allow MPPT, and allow Power Factor Correction (PFC). PFC all but eliminates the harmonic noise that can damage the wind turbine. A prototype HPS was built and evaluated that combines the two renewable sources in such a way that only two power stages are necessary, the Vienna rectifier and a step-down converter. This thesis describes the prototype and reports the results obtained.
Show less - Date Issued
- 2011
- Identifier
- CFH0004087, ucf:44799
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004087
- Title
- A Lab-Scale Experimental Framework for Studying the Phenomenon of Autorotation.
- Creator
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Rimkus, Sigitas, Das, Tuhin, Xu, Yunjun, Simaan, Marwan, University of Central Florida
- Abstract / Description
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While wind energy has emerged as a popular source of renewable energy, the traditional wind turbine has an inherent limitation, namely that it only generates power in the presence of sufficiently high and consistent wind speeds. As a result, wind farms are typically built in areas with a high probability of the required wind speeds, which are geographically sparse. One way of overcoming this drawback is to tap into the energy available in winds at high altitudes which are not only consistent...
Show moreWhile wind energy has emerged as a popular source of renewable energy, the traditional wind turbine has an inherent limitation, namely that it only generates power in the presence of sufficiently high and consistent wind speeds. As a result, wind farms are typically built in areas with a high probability of the required wind speeds, which are geographically sparse. One way of overcoming this drawback is to tap into the energy available in winds at high altitudes which are not only consistent and of high magnitude, but also globally pervasive. An airborne wind energy device based upon the phenomenon of autorotation could potentially be used to exploit the abundance of wind of energy present at high altitudes.The work in this thesis first presents our study of a tethered-airfoil system as a candidate airborne wind energy (AWE) system. A mathematical model was used to show the feasibility of energy capture and the stability of the device in a wind field. Subsequently, the research identified the principle of autorotation to be better suited for high altitude energy harvesting. To this end, the thesis first presents a theoretical basis of the principle of autorotation, which is developed from existing models in literature. The model was adapted to predict aerodynamic conditions when used for harvesting energy. Encouraging simulation results prompted the main emphasis of this thesis, namely design of an experimental framework to corroborate the theory. Several experiments were devised to determine basic performance characteristics of an autogyro rotor and the data from each experiment is presented. A lab-scale experimental setup was developed as part of this thesis. The setup, consisting of a flapping-blade autogyro rotor and sensors, was used to acquire preliminary aerodynamic performance data. It is envisioned that refinements to this setup will ultimately provide a means of directly comparing analytical and experimental data. In this regard, we provide conclusions and make comments on improvements for future experiments.
Show less - Date Issued
- 2014
- Identifier
- CFE0005239, ucf:50593
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005239
- Title
- Dynamic Modeling of Autorotation for Simultaneous Lift and Wind Energy Extraction.
- Creator
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Mackertich, Sadaf, Das, Tuhin, Moslehy, Faissal, Xu, Yunjun, University of Central Florida
- Abstract / Description
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The goal of this thesis is to develop a multi-body dynamics model of autorotation with the objective of studying its application in energy harvesting. A rotor undergoing autorotation is termed an Autogyro. In the autorotation mode, the rotor is unpowered and its interaction with the wind causes an upward thrust force. The theory of an autorotating rotorcraft was originally studied for achieving safe flight at low speeds and later used for safe descent of helicopters under engine failure. The...
Show moreThe goal of this thesis is to develop a multi-body dynamics model of autorotation with the objective of studying its application in energy harvesting. A rotor undergoing autorotation is termed an Autogyro. In the autorotation mode, the rotor is unpowered and its interaction with the wind causes an upward thrust force. The theory of an autorotating rotorcraft was originally studied for achieving safe flight at low speeds and later used for safe descent of helicopters under engine failure. The concept can potentially be used as a means to collect high-altitude wind energy. Autorotation is inherently a dynamic process and requires detailed models for characterization. Existing models of autorotation assume steady operating conditions with constant angular velocity of the rotor. The models provide spatially averaged aerodynamic forces and torques. While these steady-autorotation models are used to create a basis for the dynamic model developed in this thesis, the latter uses a Lagrangian formulation to determine the equations of motion. The aerodynamic effects on the blades that produce thrust forces, in-plane torques, and out-of-plane torques, are modeled as non-conservative forces within the Lagrangian framework. To incorporate the instantaneous aerodynamic forces, the above-mentioned spatial averaging is removed. The resulting model is causal and consists of a system of differential equations. To investigate the dynamics under energy-harvesting operation, an additional in-plane regenerative torque is added to simulate the effect of a generator. The aerodynamic effects of this regenerative braking is incorporated into the model. In addition, the dynamic model relaxes assumptions of small flapping angles, and the periodic flapping behavior of the blades are naturally generated by the dynamics instead of assuming Fourier expansions. The dynamic model enables the study of transients due to change in operating conditions or external influences such as wind speeds. It also helps gain insight into force and torque fluctuations.Model verification is conducted to ensure that the dynamic model produces similar steady-operating conditions as those reported in prior works. In addition, the behavior of autorotation under energy harvesting is evaluated. The thesis also explores the viability of achieving sufficient lift while extracting energy from prevailing winds. A range of regenerative torques are applied to determine the optimal energy state. Finally, a complete high-altitude energy harvesting system is modeled by incorporating a tether utilizing a catenary model. Overall, the thesis lends support to the hypothesis that a tethered autogyro can support its weight while harvesting energy from strong wind-fields, when augmented with appropriate control systems.
Show less - Date Issued
- 2016
- Identifier
- CFE0006138, ucf:51173
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006138
- Title
- Sustainability Assessment of Wind Energy for Buildings.
- Creator
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Noori, Mehdi, Tatari, Mehmet, Oloufa, Amr, Nam, Boo Hyun, University of Central Florida
- Abstract / Description
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Due to increasing concerns for global climate change, onshore and offshore wind energy technologies have stimulated a tremendous interest worldwide, and are considered as a viable solution to mitigate the environmental impacts related to electricity generation. Although wind energy technologies have been considered as one of the cleanest energy sources, they have a wide range of direct and indirect environmental impacts when the whole supply chain is considered. This study aims to quantify...
Show moreDue to increasing concerns for global climate change, onshore and offshore wind energy technologies have stimulated a tremendous interest worldwide, and are considered as a viable solution to mitigate the environmental impacts related to electricity generation. Although wind energy technologies have been considered as one of the cleanest energy sources, they have a wide range of direct and indirect environmental impacts when the whole supply chain is considered. This study aims to quantify the direct and indirect environmental impacts of onshore and offshore wind power technologies by tracing all of the economy-wide supply chain requirements. To accomplish this goal, we developed a comprehensive hybrid life cycle assessment (LCA) model in which process-based LCA model is combined with the economic input-output (EIO) analysis. The analysis results show that on average, concrete and steel and their supply chains are responsible for 37% and 24% of carbon footprint, consequently. On average, offshore wind turbines produce 48% less greenhouse gas emissions per kWh produced electricity than onshore wind turbines. For the onshore wind turbines, concrete, aggregates, and crushed stone approximately consume 95% of total water in this construction phase. On the other hand, concrete, lead, copper, and aggregate are responsible for around 90% of total water for the offshore wind turbines. It is also found that the more capacity the wind turbine has, the less environmental impact the wind turbine generates per kWh electricity. Moreover, based on the economic and environmental impacts of studied wind turbines and also three more nonrenewable energy sources, this study develops a decision making framework to understand the best energy source mix for a building in the state of Florida. This framework accounts for the uncertainty in the input material by deploying a Monte Carlo simulation approach. The results of decision making framework show that natural gas is a better option among nonrenewable sources. On the other hand, V90-3.0 MW offshore wind turbine is the best source of energy among renewable energy sources for a building.The findings of this research are critical for policy makers to understand the direct and indirect environmental impacts of different onshore and offshore wind energy systems. Also this study furnishes the decision maker with a range of possible energy mixes based on different economic and environmental weights.
Show less - Date Issued
- 2013
- Identifier
- CFE0005038, ucf:50017
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005038
- Title
- Data-driven Predictive Analytics For Distributed Smart Grid Control: Optimization of Energy Storage, Voltage and Demand Response.
- Creator
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Valizadehhaghi, Hamed, Qu, Zhihua, Behal, Aman, Atia, George, Turgut, Damla, Pensky, Marianna, University of Central Florida
- Abstract / Description
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The smart grid is expected to support an interconnected network of self-contained microgrids. Nonetheless, the distributed integration of renewable generation and demand response adds complexity to the control and optimization of smart grid. Forecasts are essential due to the existence of stochastic variations and uncertainty. Forecasting data are spatio-temporal which means that the data correspond to regular intervals, say every hour, and the analysis has to take account of spatial...
Show moreThe smart grid is expected to support an interconnected network of self-contained microgrids. Nonetheless, the distributed integration of renewable generation and demand response adds complexity to the control and optimization of smart grid. Forecasts are essential due to the existence of stochastic variations and uncertainty. Forecasting data are spatio-temporal which means that the data correspond to regular intervals, say every hour, and the analysis has to take account of spatial dependence among the distributed generators or locations. Hence, smart grid operations must take account of, and in fact benefit from the temporal dependence as well as the spatial dependence. This is particularly important considering the buffering effect of energy storage devices such as batteries, heating/cooling systems and electric vehicles. The data infrastructure of smart grid is the key to address these challenges, however, how to utilize stochastic modeling and forecasting tools for optimal and reliable planning, operation and control of smart grid remains an open issue.Utilities are seeking to become more proactive in decision-making, adjusting their strategies based on realistic predictive views into the future, thus allowing them to side-step problems and capitalize on the smart grid technologies, such as energy storage, that are now being deployed atscale. Predictive analytics, capable of managing intermittent loads, renewables, rapidly changing weather patterns and other grid conditions, represent the ultimate goal for smart grid capabilities.Within this framework, this dissertation develops high-performance analytics, such as predictive analytics, and ways of employing analytics to improve distributed and cooperative optimization software which proves to be the most significant value-add in the smart grid age, as new network management technologies prove reliable and fundamental. Proposed optimization and control approaches for active and reactive power control are robust to variations and offer a certain level of optimality by combining real-time control with hours-ahead network operation schemes. The main objective is managing spatial and temporal availability of the energy resources in different look-ahead time horizons. Stochastic distributed optimization is realized by integrating a distributed sub-gradient method with conditional ensemble predictions of the energy storage capacity and distributed generation. Hence, the obtained solutions can reflect on the system requirements for the upcoming times along with the instantaneous cooperation between distributed resources. As an important issue for smart grid, the conditional ensembles are studied for capturing wind, photovoltaic, and vehicle-to-grid availability variations. The following objectives are pursued:- Spatio-temporal adaptive modeling of data including electricity demand, electric vehicles and renewable energy (wind and solar power)- Predictive data analytics and forecasting- Distributed control- Integration of energy storage systemsFull distributional characterization and spatio-temporal modeling of data ensembles are utilized in order to retain the conditional and temporal interdependence between projection data and available capacity. Then, by imposing measures of the most likely ensembles, the distributed control method is carried out for cooperative optimization of the renewable generation and energy storage within the smart grid.
Show less - Date Issued
- 2016
- Identifier
- CFE0006408, ucf:51481
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006408