Dissertations / Theses on the topic 'Small wind system'

The UK has committed to sourcing 15% of its energy from renewable sources by 2020 and wind turbines have the potential to contribute towards this target. Due to the Feed-In-Tariffs introduced by the UK Government in 2010, the potential uptake of micro-generation methods such as small wind is likely to increase. However, many barriers exist which prevent widespread implementation, such as noise concerns. There is little work available in the open literature quantifying the problem because much of the existing research focuses on large scale turbines. The need for an increase in interdisciplinary research in this area has also been called for. This research fills the gap in the literature by seeking to better understand the noise levels generated by small wind systems, the characteristics of the noise and people’s reactions to this noise. The research is interdisciplinary, incorporating engineering, to measure, characterise and model the noise from small wind systems and psychology, to identify the type of people who are most likely to perceive the noise. Environmental noise measurements have been taken at small wind system installations to quantify and characterise the noise levels. This work included an assessment of the attenuation of the noise. Studies have been carried out on individuals living close to small wind system installations, as well as individuals being played recordings of wind turbine noise to investigate the level and type of noise they perceive and to link this to an individual’s attitude towards wind turbines, personality traits and symptom reporting. CFD has been used to model the flow fields around 2D blade sections to identify the likely noise mechanisms associated with small wind systems by observing the turbulent regions near the aerofoil wall. Finally, a comparison of the three methods has been carried out to identify that the overall level of small wind system noise is low but it is the nature of the sounds that increase the likely perception of the noise.

Thesis (S.M. in System Design and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, June 2010.
"May 2010." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-80).
A student group at MIT in cooperation with the MIT Department of Facilities is currently working to install a Skystream 3.7 wind turbine on MIT's campus. This has raised several questions about how to best develop small wind projects in urban environments. The best wind resources in the country exist in relatively remote locations and require large investments in electricity transmission infrastructure to be effectively utilized. In the meantime, several large and small projects have been developed in the Boston area. The urban environment presents many challenges to development including the interaction of urban buildings with wind flow, concerns from neighbors and government over the aesthetics and safety of turbines that are installed near human populations, environmental effects including wildlife, noise, and shadows. There are also many opportunities including the ability to use net metering, little or no transmission infrastructure costs, and the ability to build on existing wind resource data and project assessments to develop a large number of installations. This document presents an overview of how the challenges of small wind turbine development in urban, suburban, and rural neighborhoods are currently being addressed by research in new and improved technology for turbines and siting, business strategies of existing companies, financing, and government policy. It looks at the strategy options available to businesses involved development of small wind turbines and evaluates the relative strengths and weaknesses of these strategies in a rapidly changing marketplace.
by Kevin Ferrigno.
S.M.in System Design and Management

This paper investigates the concept of an isolated small wind power system based on a three-phase generator and a direct ac-to-ac conversion. The ac-to-ac conversion is performed by a matrix converter and thus removing the need of a large smoothing capacitor in the typical rectifier-inverter solution. The paper is briefly presenting the operation for a particular topology of a three-phase to single-phase matrix converter. The control of this conversion ensures system’s frequency and voltage stability. Simulation results and practical results are presented to validate the frequency and voltage regulation of the isolated power system.

Small-scale renewable energy systems are becoming increasingly popular due to soaring fuel prices and due to technological advancements which reduce the cost of manufacturing. Solar and wind energies, among other renewable energy sources, are the most available ones globally. The hybrid photovoltaic (PV) and wind power system has a higher capability to deliver continuous power with reduced energy storage requirements and therefore results in better utilization of power conversion and control equipment than either of the individual sources. Power conditioning units (p.c.u.) for such small-scale hybrid PV-wind generation systems have been proposed in this study. The system was connected to the grid, but it could also operate in standalone mode if the grid was unavailable. The system contains a local controller for every energy source and the grid inverter. Besides, it contains the supervisory controller. For the wind generator side, small-scale vertical axis wind turbines (VAWTs) are attractive due to their ability to capture wind from different directions without using a yaw. One difficulty with VAWTs is to prevent over-speeding and component over-loading at excessive wind velocities. The proposed local controller for the wind generator is based on the current and voltage measured on the dc side of the rectifier connected to the permanent magnet synchronous generator (PMSG). Maximum power point tracking (MPPT) control is provided in normal operation under the rated speed using a dc/dc boost converter. For high wind velocities, the suggested local controller controls the electric power in order to operate the turbine in the stall region. This high wind velocity control strategy attenuates the stress in the system while it smoothes the power generated. It is shown that the controller is able to stabilize the nonlinear system using an adaptive current feedback loop. Simulation and experimental results are presented. The PV generator side controller is designed to work in systems with multiple energy sources, such as those studied in this thesis. One of the most widely used methods to maximize the output PV power is the hill climbing technique. This study gives guidelines for designing both the perturbation magnitude and the time interval between consecutive perturbations for such a technique. These guidelines would improve the maximum power point tracking efficiency. According to these guidelines, a variable step MPPT algorithm with reduced power mode is designed and applied to the system. The algorithm is validated by simulation and experimental results. A single phase H-bridge inverter is proposed to supply the load and to connect the grid. Generally, a current controller injects active power with a controlled power factor and constant dc link voltage in the grid connected mode. However, in the standalone mode, it injects active power with constant ac output voltage and a power factor which depends on the load. The current controller for both modes is based on a newly developed peak current control (p.c.c.) with selective harmonic elimination. A design procedure has been proposed for the controller. Then, the method was demonstrated by simulation. The problem of the dc current injection to the grid has been investigated for such inverters. The causes of dc current injection are analyzed, and a measurement circuit is then proposed to control the inverter for dc current injection elimination. Characteristics of the proposed method are demonstrated, using simulation and experimental results. At the final stage of the study, a supervisory controller is demonstrated, which manages the different operating states of the system during starting, grid-connected and standalone modes. The operating states, designed for every mode, have been defined in such a hybrid model to allow stability and smooth transition between these states. The supervisory controller switches the system between the different modes and states according to the availability of the utility grid, renewable energy generators, the state of charge (SOC) of energy storage batteries, and the load. The p.c.u. including the supervisory controller has been verified in the different modes and states by simulation.

This dissertation aims to present detailed analysis of the small scale wind energy conversion system (WECS) design and implementation. The dissertation will focus on implementing a hardware prototype to be used for testing different control strategies applied to small scale WECSs. Novel control algorithms will be proposed to the WECS and will be verified experimentally in details. The wind turbine aerodynamics are presented and mathematical modeling is derived which is used then to build wind simulator using motor generator (MG) set. The motor is torque controlled based on the turbine mathematical model and the generator is controlled using the power electronic conversion circuits. The power converter consists of a three phase diode bridge followed by a boost converter. The small signal modeling for the motor, generator, and power converter are presented in details to help building the needed controllers. The main objectives of the small scale WECS controller are discussed. This dissertation focuses on two main regions of wind turbine operation: the maximum power point tracking (MPPT) region operation and the stall region operation. In this dissertation, the concept of MPPT is investigated, and a review of the most common MPPT algorithms is presented. The advantages and disadvantaged of each method will be clearly outlined. The practical implementation limitation will be also considered. Then, a MPPT algorithm for small scale wind energy conversion systems will be proposed to solve the common drawback of the conventional methods. The proposed algorithm uses the dc current as the perturbing variable and the dc link voltage is considered as a degree of freedom that will be utilized to enhance the performance of the proposed algorithm. The algorithm detects sudden wind speed changes indirectly through the dc link voltage slope. The voltage slope is also used to enhance the tracking speed of the algorithm and to prevent the generator from stalling under rapid wind speed slow down conditions. The proposed method uses two modes of operation: A perturb and observe (PandO) mode with adaptive step size under slow wind speed fluctuation conditions, and a prediction mode employed under fast wind speed change conditions. The dc link capacitor voltage slope reflects the acceleration information of the generator which is then used to predict the next step size and direction of the current command. The proposed algorithm shows enhanced stability and fast tracking capability under both high and low rate of change wind speed conditions and is verified using a 1.5-kW prototype hardware setup. This dissertation deals also with the WECS control design under over power and over speed conditions. The main job of the controller is to maintain MPPT while the wind speed is below rated value and to limit the electrical power and mechanical speed to be within the system ratings when the wind speed is above the rated value. The concept of stall region and stall control is introduced and a stability analysis for the overall system is derived and presented. Various stall region control techniques are investigated and a new stall controller is proposed and implemented. Two main stall control strategies are discussed in details and implemented: the constant power stall control and the constant speed stall control. The WECS is expected to work optimally under different wind speed conditions. The system should be designed to handle both MPPT control and stall region control at the same time. Thus, the control transition between the two modes of operation is of vital interest. In this dissertation, the light will be shed on the control transition optimization and stabilization between different operating modes. All controllers under different wind speed conditions and the transition controller are designed to be blind to the system parameters pre knowledge and all are mechanical sensorless, which highlight the advantage and cost effectiveness of the proposed control strategy. The proposed control method is experimentally validated using the WECS prototype developed. Finally, the proposed control strategies in different regions of operation will be successfully applied to a battery charger application, where the constraints of the wind energy battery charger control system will be analyzed and a stable and robust control law will be proposed to deal with different operating scenarios.
Ph. D.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008.
The sustainability and economy of the current South African National Antarctic Expedition IV (SANAE IV) base diesel-electric power system are threatened by the current high fuel prices and the environmental pollution reduction obligations. This thesis presents the potential technical, environmental and economical challenges associated with the integration of small wind energy conversion system (WECS) with the current SANAE IV diesel fuelled power system. Criteria derived from technical, environmental and economic assessments are applied in the evaluation of eight commercially available wind turbines as to determine the most technically and economically feasible candidates. Results of the coastal Dronning Maud Land and the local Vesleskarvet cold climate assessments based on long term meteorological data and field data are presented. Field experiments were performed during the 2007-2008 austral summer. These results are applied in the generation of a wind energy resource map and in the derivation of technical wind turbine evaluation criteria. The SANAE IV energy system and the electrical grid assessments performed are based on long term fuel consumption records and 2008 logged data. Assessment results led to the identification of SANAE IV specific avoidable wind turbine grid integration issues. Furthermore, electro-technical criteria derived from these results are applied in the evaluation of the eight selected wind turbines. Conceptual wind turbine integration options and operation modes are also suggested. Wind turbine micro-siting incorporating Vesleskarvet specific climatological, environmental and technical related issues are performed. Issues focusing on wind turbine visual impact, air traffic interference and the spatial Vesleskarvet wind distribution are analysed. Three potential sites suited for the deployment of a single or, in the near future, a cluster of small wind turbines are specified. Economics of the current SANAE IV power system based on the South African economy (May 2008) are analysed. The life cycle economic impact associated with the integration of a small wind turbine with the current SANAE IV power system is quantified. Results of an economic sensitivity analysis are used to predict the performance of the proposed wind-diesel power systems. All wind turbines initially considered will recover their investment costs within 20 years and will yield desirable saving as a result of diesel fuel savings, once integrated with the SANAE IV diesel fuelled power system. Finally, results of the technical and economical evaluation of the selected commercially available wind turbines indicated that the Proven 6 kWrated, Bergey 10 kWrated and Fortis 10 kWrated wind turbines are the most robust and will yield feasible savings.

Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.
24
Cataloged from PDF version of thesis. Title as it appears in June 6, 2014 commencement exercises program: Analysis of stability and dynamics of double-fed induction machines in the wind turbine system.
Includes bibliographical references (pages 76-77)
This project represents the physical modeling and experimental test of a Doubly-fed Induction Machine (DFIM), in order to substantially analyze the characteristic behaviors of wind turbines and its use in the micro-grid network. The environment set-up is based on a smart micro-grid system, which consists of the grid, a diesel generator, a solar panel, and a wind farm. The hardware work includes the design of a 2.5kW inverter and a L-C-L grid filter (including inductor design and construction). The goal of this research is to better emulate the operation principles of wind turbine system. Future work proposes developing a better control method to improve the stability and reliability of the wind turbine system. Keywords: DFIM, micro-grid, space vector PWM, DTC-SVM, back-to-back inverter, inductor design, and grid filter.
by Xuntuo Wang.
S.M.

In this dissertation I present my approach and findings regarding the development of a simulation model for a small scale renewable energy system. A brief introduction provides the reader with the background as to why there is a need for such a simulation package. The project objectives, research methodology and the research contributions originating from the project is also described. A literature study was done on all the relevant technologies constituting the renewable energy system as well as the techniques required to model the system. A system breakdown identified the various sub modules as well as how they interface with each other. The simulation model was tested by using Alexander bay, South Africa, as a case study. The results obtained from the various modules were discussed and found to correlate with what was expected. Although not contained within the project’s scope, an additional analysis of the effect of the wind data’s resolution on the probable power output of a wind turbine was performed leading to a hypothesis regarding the estimation of a more accurate probable power output extrapolation from data with a coarse resolution.
Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013

The aim of the research is to produce a methodology for the siting of small-scale, embedded wind generators, and implement this within a commercial software package designed to use existing digital data sets. There is a widespread opportunity to exploit smaller size developments, but potentially large numbers of suitable sites means that an automated screening process is essential. Much of the information required for such a siting study is spatial in nature and hence the site identification process can be facilitated using a geographical information system - GIS. The literature has revealed a number of GIS-based assessments, but these have concentrated on large wind farms, and have been undertaken at relatively coarse resolution. In contrast, this research has produced a much more sophisticated tool, allowing analysis at much finer resolution and encompassing a wider range of relevant factors. An attractive site for a wind turbine development requires more than just a suitable wind resource; factors such as environmental acceptability, public safety, physical constraints such as land use and impact on the electricity supply system will all determine the potential of a site. Constraints and parameters have been derived describing these factors and from these algorithms and inference rules have been developed. These have been coded up for use with a proprietary GIS package, producing a tool that can be widely applied. In particular, it has been demonstrated for a test region in Shropshire, UK. A particular emphasis of this study is the consideration of the impact on the electricity network. Relatively, few small installations have been connected to the national electricity grid in the UK; there is a range of reasons for this, a lack of suitable siting tool being one. Connection to the 11 kV network has been assumed given its relevance to smaller scale installations. This can result in a lower grid connection cost than for typical large-scale wind farm arrangements, for which connection usually represents a major element in the overall project costs. Often these low voltage lines are weak (i.e. susceptible to voltage variation), especially in remote rural areas. An appraisal of the impact of such embedded generators is important and is an intrinsic part of the methodology presented and implemented here.

According to the International Energy Agency 2016 statistics, Ethiopia is among the lowest countries in annual electricity consumption, 70 KWh/capita. Rural areas hold more than 80% of the country’s population and less than 30% of them have been electrified. Most of the population (the rural areas) still predominantly depend on traditional biomass energy sources for cooking and heating, and household lights are provided mainly by kerosene and biomass including this study area, Tadacha Rarasa, which consist of 4100 households with 6 members, totally 24,600 people[1, 2]. The feasibility study of hybrid system consisting of small Hydro, PV, Wind and Battery is carried out using HOMER as a tool for optimization and sensitivity analysis. TURBNPRO software also assists for the optimization of the small hydropower which is suggested to utilize the 2.2 m3/s ecological flow of the Genale 3 multipurpose hydropower plant’s reservoir. The wind speed and solar radiation data of the site is collected from NASA. Then, the wind speed, solar radiation, electric load and hydro data is input to HOMER in their respective appropriate format for simulation and analysis of the proposed hybrid system.  Electric loads of the community is estimated bearing in mind the irrigation, fishery and other opportunities which will arise after the multipurpose project completion in addition to basic household demands. The daily average estimated residential consumption by each family is 9.118 kWh and the daily average total energy consumption per person is 1.872 kWh.   After optimization and sensitivity analysis using HOMER, several different feasible configurations of Hydro, PV, Wind and Battery hybrid system has been displayed with a range of 0.049 to 0.067 $/kWh cost of energy. The optimum configuration becomes Hydro/PV/Battery hybrid system with 0.049 $/kWh levelized COE which is closer to the national energy tariff, 0.032 USD/kWh. The optimum Hydro/PV/Battery hybrid system generates annually 18,647,372 kWh with 0.18% capacity shortage and 0.15% unmet load. The hydropower supports the base load and the PV supplies for the peak load demand in the daytime which shares 19% of the total electric production.

Thesis (MScEng)--Stellenbosch University, 2013.
Wind energy has proven to be a viable source of clean energy, and the worldwide demand is growing rapidly. Variable speed topologies, with synchronous generators and full-scale converters, are becoming more popular, and the e ective control of these systems is a current trend in wind energy research. The purpose of this study is the modelling, design, simulation and implementation of a small-scale, variable speed wind energy conversion system, incorporating the position sensorless direct torque control with space vector modulation, of a permanent magnet synchronous generator, including an RLC converter lter. Another aim is the development of a gain scheduling algorithm that facilitates the high level control of the system. Mathematical models of the combined lter-generator model, in the stationary and rotating reference frames, are presented and discussed, from which equivalent approximate transfer functions are derived for the design of the controller gains. The design of the controller gains, RLC lter components, gain scheduling concept and maximum power point tracking controller are presented. It is discovered that the RLC lter damping resistance has a signi cant e ect on the resonance frequency of the system. The system is simulated dynamically in both Simulink and the VHDL-AMS programming language. Additionally, the maximum power point tracking controller is simulated in the VHDL-AMS simulation, including a wind turbine simulator. The simulation results demonstrate good dynamic performance, as well as the variable speed operation of the system. The practical results of torque and speed controllers show satisfactory performance, and correlate well with simulated results. The detailed gain scheduling algorithm is presented and discussed. A nal test of the complete system yields satisfactory practical results, and con rms that the objectives of this thesis have been reached.

The atmospheric boundary layer (ABL) is the layer of air directly influenced by the Earth’s surface and is the layer of the atmosphere most important to humans as this is the air we live in. Methods for measuring the properties of the ABL include three general approaches: satellite-based, ground- based and airborne. A major research challenge is that many contemporary methods provide a restricted spatial resolution or coverage of variations of ABL properties such as how wind speed varies across a landscape with complex topography. To enhance our capacity to measure the properties of the ABL, this thesis presents a new technique that involves a small unmanned aircraft system (sUAS) equipped with a customized payload for measuring wind speed and particulate matter. The research presented herein outlines two key phases in establishing the proof-of-concept of the payload and its integration on the sUAS: (1) design and testing and (2) field demonstration. The first project focuses on measuring wind speed, which has been measured with fixed wing sUASs in previous research, but not with a helicopter sUAS. The second project focuses on the measurement of particulate matter, which is a major air pollutant typically measured with ground- based sensors. Results from both proof-of-concept projects suggest that ABL research could benefit from the proposed techniques.

Nowadays, power systems are dealing with some new challenges raisedby the major changes that have been taken place since 80’s, e.g., deregu-lation in electricity markets, significant increase of electricity demands andmore recently large-scale integration of renewable energy resources such aswind power. Therefore, system operators must make some adjustments toaccommodate these changes into the future of power systems.One of the main challenges is maintaining the system stability since theextra stress caused by the above changes reduces the stability margin, andmay lead to rise of many undesirable phenomena. The other important chal-lenge is to cope with uncertainty and variability of renewable energy sourceswhich make power systems to become more stochastic in nature, and lesscontrollable.Flexible AC Transmission Systems (FACTS) have emerged as a solutionto help power systems with these new challenges. This thesis aims to ap-propriately utilize such devices in order to increase the transmission capacityand flexibility, improve the dynamic behavior of power systems and integratemore renewable energy into the system. To this end, the most appropriatelocations and settings of these controllable devices need to be determined.This thesis mainly looks at (i) rotor angle stability, i.e., small signal andtransient stability (ii) system operation under wind uncertainty. In the firstpart of this thesis, trajectory sensitivity analysis is used to determine themost suitable placement of FACTS devices for improving rotor angle sta-bility, while in the second part, optimal settings of such devices are foundto maximize the level of wind power integration. As a general conclusion,it was demonstrated that FACTS devices, installed in proper locations andtuned appropriately, are effective means to enhance the system stability andto handle wind uncertainty.The last objective of this thesis work is to propose an efficient solutionapproach based on Benders’ decomposition to solve a network-constrained acunit commitment problem in a wind-integrated power system. The numericalresults show validity, accuracy and efficiency of the proposed approach.

The Doctoral Degrees issued upon completion of the programme are issued by Comillas Pontifical University, Delft University of Technology and KTH Royal Institute of Technology. The invested degrees are official in Spain, the Netherlands and Sweden, respectively.QC 20141028

As wind turbines are increasingly being adopted for meeting growing energy needs, their implementation for personal home use in the near future is imminent. There are very few studies conducted on small-scale turbines in the one to two meter diameter range because the power generated at this scale is currently not sufficient to justify the cost of installation and maintenance. The problem is further complicated by the fact that these turbines are normally mounted at low altitudes and thus there is necessity to have the optimum operating regime in the wind speed range of 3-10 mph (1.34 -- 4.47 m/s). This thesis discusses two methods for increasing the efficiency of horizontal axis small-scale wind energy conversion systems, 1) adding a diffuser to increase the wind speed at the rotor and 2) designing tubercles to enhance the flow characteristics over blades. Further, it was identified during the course of thesis that for simple installation and maintenance in the residential areas vertical axis turbines are advantageous. Thus, the second chapter of this thesis addresses the design of vertical axis turbines with power generation capability suitable for that of a typical US household.
    The study of the diffuser augmented wind turbine provides optimum dimensions for achieving high power density that can address the challenges associated with small scale wind energy systems; these challenges are to achieve a lower start-up speed and low wind speed operation. The diffuser design was modeled using commercial computational fluid dynamics code. Two-dimensional modeling using actuator disk theory was used to optimize the diffuser design. A statistical study was then conducted to reduce the computational time by selecting a descriptive set of models to simulate and characterize relevant parameters\' effects instead of checking all the possible combinations of input parameters. Individual dimensions were incorporated into JMP® software and randomized to design the experiment. The results of the JMP® analysis are discussed in this paper. Consistent with the literature, a long outlet section with length one to three times the diameter coupled with a sharp angled inlet was found to provide the highest amplification for a wind turbine diffuser.
    The second study consisted of analyzing the capabilities of a small-scale vertical axis wind turbine. The turbine consisted of six blades of extruded aluminum NACA 0018 airfoils of 0.08732 m (3.44 in) in chord length. Small-scale wind turbines often operate at Reynolds numbers less than 200,000, and issues in modeling their flow characteristics are discussed throughout this thesis. After finding an appropriate modeling technique, it was found that the vertical axis wind turbine requires more accurate turbulence models to appropriately discover its performance capabilities.
    The use of tubercles on aerodynamic blades has been found to delay stall angle and increase the aerodynamic efficiency. Models of 440 mm (17.33 in) blades with and without tubercles were fabricated in Virginia Tech\'s Center for Energy Harvesting Materials and Systems (CEHMS) laboratory. Comparative analysis using three dimensional models of the blades with and without the tubercles will be required to determine whether the tubercle technology does, in fact, delays the stall. Further computational and experimental testing is necessary, but preliminary results indicate a 2% increase in power coefficient when tubercles are present on the blades.

Master of Science

Buildings account for up to 40% of the total energy use in the world. Directives from the European Union have pointed out the significance of increasing the energy efficiency in buildings. New regulation in countries like Sweden has established that new buildings should fulfil regulations of Nearly Zero Energy Buildings (NZEB), providing the opportunity for renewable energy technologies to achieve these goals. In this paper, the retrofitting potential of renewable energy technologies for a single-family home in Sweden was investigated.The present work studied the characteristics of several renewable energy technologies and their applications for a single-family home in Sweden, including biomass, solar photovoltaics, solar thermal, heat pump, and small-scale wind turbine. Three renewable energy technologies (solar thermal, heat pump and small-scale wind turbine) and one renovation method (window) were selected to investigate. The analysis was made of the current energy use and the potential energy (and cost) savings from each retrofitting of these facilities by means of simulation models using IDA ICE software. The study results show that the proposed renewable energy technologies are technically feasible and economically viable as a source of alternative renewable energy in order to produce clean energy and reduce electricity bills for an electric-heated single-family home located in Sweden. Moreover, the combined retrofitting scheme consist of solar thermal system and window renovation was also proposed and explored. As a result the energy performance of the single-family home would satisfy the nearly-zero energy building requirements and thermal comfort could be maintained at an acceptable level.

Small wind turbines, and especially urban-mounted turbines which require no dedicated pole, have garnered great public enthusiasm in recent years. This enthusiasm has fueled widespread growth among energy conservationists, and estimates predict that the power produced nationally by small wind will increase thirty-fold by 2013. Unfortunately, most of the wind resources currently available have been designed for larger, rural-mounted turbines; thus, they are not well suited for this nascent market. A consequence of this is that many potential urban small wind turbine owners over-predict their local wind resource, which is both costly and inefficient. According to a recent study published by Encraft Ltd., small wind turbines mounted to buildings far underperformed their rural pole mounted counterparts. As a proposed solution to this problem, this project introduces the concept of a Web-based Wind Assessment System (WWAS). This system combines all the necessary resources for potential urban small wind turbine customers into a single web-based tool. The system also presents the concept of a modular wind measurement system, which couples with the WWAS to provide real-time wind data measurements. The benefits of the system include its ease of use, flexibility of installation, data accessibility from any web browser, and expert advice. The WWAS prevents potential clients from investing in a system that may not be viable for their location. In addition, a small wind turbine is designed in this project, which has a unique modular mounting system, allowing the same baseline wind turbine to attach to various structures using interchangeable mounting hardware. This includes such accessible urban structures as street lights, building corners, flag poles, and building walls, among others. This design also utilizes concepts that address some of the challenges associated with mounting small wind turbines to existing urban structures. These concepts include: swept tip blades and lower RPM to reduce noise; vibration suppression using rubber shims; a netted duct to protect wildlife; and a direct-drive permanent magnet generator to ensure low starting torque. Finally, the cost of this system is calculated using off-the-shelf components, which minimize testing and certification expense. This small wind turbine system is designed to be grid-connected, has a 6 foot diameter rotor, and is rated at 1 kW. This design features a unique modular interchangeable mounting system. The cost for this complete system is estimated to be $2,050. If a users' site has an average wind speed of 14 mph (6.5 m/s), this system will generate a return on investment in 8.5 years, leaving over 10 years of profit. The profit for this system, at this sample average wind speed, yields over $4,000 during its 20-year design life, which is a two-fold return on investment. This project has implications for various stakeholders in the small wind turbine market, including designers, engineers, manufacturers, and potential customers. Equally important is its potential role in guiding our future national--even global--energy agenda.

In recent years, the need for personal urban mobility has increased a lot especially in emerging and developing countries. It becomes increasingly important to explore propulsion systems that use alternative energy sources and are related to the chain of production, storage and use of renewable energy. Several studies have been conducted in this area, but very few have achieved solutions for the interaction of the vehicle with the building by which it is parked in terms of a multi-energy exchange. Technological innovation of house plant parts, of large residences / hotels, of shelter stations for vehicles, it is now crucial to implement the integration of more renewable energy sources within the same building structure: this is one of the aspects covered by the most general definition of "Smart Housing". Sustainable mobility is perceived as a strong need to match individual urban and sub-urban mobility, to the least environmental and social impact of such personal need. This research project proposes a possible scenario for energy integration between smart housing and smart mobility using a common energy platform that allows self-generation, storage and energy exchange between residential district buildings and smart vehicles. The project integrates multidisciplinary approaches with the aim of designing, evaluating technical and industrial feasibility for the development of: 1) Modular and scalable energy storage devices dedicated to a smart house. 2) a modular city vehicle, with high flexibility of use, with energy storage system and energy-efficient switching capabilities with smart building.

A detailed study of the fatigue life of wooden wind turbine blades for a new 10 kilowatt system was undertaken. A numerical model of the blades was created using the technical software package MATLAB in order to estimate the maximum stress occurring within the blade in response to changes in wind velocities based on a wind profile approximating the location where these turbines are expected to operate. The material properties of the wooden laminate were measured using an Instron tensile test machine and were found to be in line with published values. In parallel with this effort, a three dimensional part scanner was utilized to compare the as-built blade to the theoretical profile and large differences between these two profiles were observed. These studies were then used to guide the creation of a full scale fatigue test which subjected two blades to accelerated fatigue loads in order to monitor the damage accumulation within each blade. It was ultimately determined that this new blade design has a fatigue life greater than 20 years.

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 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.
B.S.
Bachelors
Engineering and Computer Science

The theory of Lagrangian Coherent Structures (LCS) enables prediction of material transport by turbulent winds, such as those observed in the Earth's Atmospheric Boundary Layer. In this dissertation, both theory and experimental methods are developed for utilizing small fixed-wing unmanned aircraft systems (UAS) in detecting these atmospheric coherent structures. The dissertation begins by presenting relevant literature on both LCS and airborne wind estimation. Because model-based wind estimation inherently depends on high quality models, a Flight Dynamic Model (FDM) suitable for a small fixed-wing aircraft in turbulent wind is derived in detail. In this presentation, some new theoretical concepts are introduced concerning the proper treatment of spatial wind gradients, and a critical review of existing theories is presented. To enable model-based wind estimation experiments, an experimental approach is detailed for identifying a FDM for a small UAS by combining existing computational aerodynamic and data-driven approaches. Additionally, a methodology for determining wind estimation error directly resulting from dynamic modeling choices is presented and demonstrated. Next, some model-based wind estimation results are presented utilizing the experimentally identified FDM, accompanied by a discussion of model fidelity concerns and other experimental issues. Finally, an algorithm for detecting LCS from a single circling fixed-wing UAS is developed and demonstrated in an Observing System Simulation Experiment. The dissertation concludes by summarizing these contributions and recommending future paths for continuing research.
Doctor of Philosophy
In a natural or man-made disaster, first responders depend on accurate predictions of where the wind might carry hazardous material. A mathematical theory of Lagrangian Coherent Structures (LCS) has shown promise in ocean environments to improve these predictions, and the theory is also applicable to atmospheric flows near the Earth’s surface. This dissertation presents both theoretical and experimental research efforts towards employing small fixed-wing unmanned aircraft systems (UAS) to detect coherent structures in the Atmospheric Boundary Layer (ABL). These UAS fit several “gaps” in available sensing technology: a small aircraft responds significantly to wind gusts, can be steered to regions of interest, and can be flown in dangerous environments without risking the pilot’s safety. A key focus of this dissertation is to improve the quality of airborne wind measurements provided by inexpensive UAS, specifically by leveraging mathematical models of the aircraft. The dissertation opens by presenting the motivation for this research and existing literature on the topics. Next, a detailed derivation of a suitable Flight Dynamic Model (FDM) for a fixed-wing aircraft in a turbulent wind field is presented. Special attention is paid to the theories for including aerodynamic effects of flying in non-uniform winds. In preparation for wind measurement experiments, a practical method for obtaining better quality FDMs is presented which combines theoretically based and data-driven approaches. A study into the wind-measurement error incurred solely by mathematical modeling is presented, focusing on simplified forms of the FDM which are common in aerospace engineering. Wind estimates which utilize our best available model are presented, accompanied by discussions of the model accuracy and additional wind measurement concerns. A method is developed to detect coherent structures from a circling UAS which is providing wind information, presumably via accurate model based estimation. The dissertation concludes by discussing these conclusions and directions for future research which have been identified during these pursuits.

This thesis describes the development of a nonlinear flight dynamics model for a small, fixed-wing unmanned aerial vehicle (UAV). Models developed for UAVs can be used for many applications including risk analysis, controls system design and flight simulators. Several challenges exist for system identification of small, low-cost aircraft including an increased sensitivity to atmospheric disturbances and decreased data quality from a cost-appropriate instrumentation system. These challenges result in difficulties in development of the model structure and parameter estimation. The small size may also limit the scope of flight test experiments and the consequent information content of the data from which the model is developed. Methods are presented to improve the accuracy of system identification which include data selection, data conditioning, incorporation of information from computational aerodynamics and synthesis of information from different flight test maneuvers. The final parameter estimation and uncertainty analysis was developed from the time domain formulation of the output-error method using the fully nonlinear aircraft equations of motion and a nonlinear aerodynamic model structure. The methods discussed increased the accuracy of parameter estimates and lowered the uncertainty in estimates compared to standard procedures for parameter estimation from flight test data. The significant contributions of this thesis are a detailed explanation of the entire system identification process tailored to the needs of a small UAV and incorporation of unique procedures to enhance identification results. This work may be used as a guide and list of recommendations for future system identification efforts of small, low-cost, minimally instrumented, fixed-wing UAVs.
MS

This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, C­p, vs. tip speed ratio, λ, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the wind turbine’s power performance as Reynolds number decreased. From Re = 2.76E5 to Re = 1.14E5, the rotor’s Cp_max changed from 0.30 to 0.19. The Cp vs. λ results also displayed a clear change in shape with decreasing Reynolds number. The analysis highlights the influence of the rotor’s Cl /Cd characteristics on the Cp vs. λ curve’s Reynolds number dependency. By not accounting for the effects of varying Reynolds number below the critical value for a rotor operating at constant λ, the design of the rotor planform may overestimate the actual performance of the turbine in real-world conditions. This problem is more evident in distributed-scale wind turbines, compared to utility-scale ones, because of the significantly shorter chord lengths, and therefore increased wind speed range where this effect occurs. Lastly, the wind turbine’s future control method and annual energy production are evaluated using the test results.

This thesis focuses on vision-based detection and observation of small, slow-moving targets using a gimballed fixed-wing unmanned aircraft system (UAS). Generally, visual tracking algorithms are tuned to detect motion of relatively large objects in the scene with noticeably significant motion; therefore, applications such as high-altitude visual searches for human motion often ignore target motion as noise. Furthermore, after a target is identified, arbitrary maneuvers for transitioning to overhead orbits for better observation may result in temporary or permanent loss of target visibility. We present guidelines for tuning parameters of the Visual Multiple Target Tracking (Visual MTT) algorithm to enhance its detection capabilities for very small, slow-moving targets in high-resolution images. We show that the tuning approach is able to detect walking motion of a human described by 10-15 pixels from high altitudes. An algorithm is then presented for defining rotational bounds on the controllable degrees of freedom of an aircraft and gimballed camera system for maintaining visibility of a known ground target. Critical rotations associated with the fastest loss or acquisition of target visibility are also defined. The accuracy of these bounds are demonstrated in simulation and simple applications of the algorithm are described for UAS. We also present a path planning and control framework for defining and following both dynamically and visually feasibly transition trajectories from an arbitrary point to an orbit over a known target for further observation. We demonstrate the effectiveness of this framework in maintaining constant target visibility while transitioning to the intended orbit as well as in transitioning to a lower altitude orbit for more detailed visual analysis of the intended target.

Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Tsiotras, Panagiotis; Committee Member: Corban, Eric; Committee Member: Feron, Eric; Committee Member: Johnson, Eric; Committee Member: Vachtsevanos, George.

The main contributions of this work are applications of robust control and analysis methods to complex engineering systems, namely, small fixed-wing unmanned aircraft systems (UAS). Multiple path-following controllers for a small fixed-wing Telemaster UAS are presented, including a linear parameter-varying (LPV) controller scheduled over path curvature. The controllers are synthesized based on a lumped path-following and UAS dynamic system, effectively combining the six degree-of-freedom aircraft dynamics with established parallel transport frame virtual vehicle dynamics. The robustness and performance of these controllers are tested in a rigorous MATLAB simulation environment that includes steady winds, turbulence, measurement noise, and delays. After being synthesized off-line, the controllers allow the aircraft to follow prescribed geometrically defined paths bounded by a maximum curvature. The controllers presented within are found to be robust to the disturbances and uncertainties in the simulation environment. A robust analysis framework for mathematical validation of flight control systems is also presented. The framework is specifically developed for the complete uncertainty characterization, quantification, and analysis of small fixed-wing UAS. The analytical approach presented within is based on integral quadratic constraint (IQC) analysis methods and uses linear fractional transformations (LFTs) on uncertainties to represent system models. The IQC approach can handle a wide range of uncertainties, including static and dynamic, linear time-invariant and linear time-varying perturbations. While IQC-based uncertainty analysis has a sound theoretical foundation, it has thus far mostly been applied to academic examples, and there are major challenges when it comes to applying this approach to complex engineering systems, such as UAS. The difficulty mainly lies in appropriately characterizing and quantifying the uncertainties such that the resulting uncertain model is representative of the physical system without being overly conservative, and the associated computational problem is tractable. These challenges are addressed by applying IQC-based analysis tools to analyze the robustness of the Telemaster UAS flight control system. Specifically, uncertainties are characterized and quantified based on mathematical models and flight test data obtained in house for the Telemaster platform and custom autopilot. IQC-based analysis is performed on several time-invariant H∞ controllers along with various sets of uncertainties aimed at providing valuable information for use in controller analysis, controller synthesis, and comparison of multiple controllers. The proposed framework is also transferable to other fixed-wing UAS platforms, effectively taking IQC-based analysis beyond academic examples to practical application in UAS control design and airworthiness certification. IQC-based analysis problems are traditionally solved using convex optimization techniques, which can be slow and memory intensive for large problems. An oracle for discrete-time IQC analysis problems is presented to facilitate the use of a cutting plane algorithm in lieu of convex optimization in order to solve large uncertainty analysis problems relatively quickly, and with reasonable computational effort. The oracle is reformulated to a skew-Hamiltonian/Hamiltonian eigenvalue problem in order to improve the robustness of eigenvalue calculations by eliminating unnecessary matrix multiplications and inverses. Furthermore, fast, structure exploiting eigensolvers can be employed with the skew-Hamiltonian/Hamiltonian oracle to accurately determine critical frequencies when solving IQC problems. Applicable solution algorithms utilizing the IQC oracle are briefly presented, and an example shows that these algorithms can solve large problems significantly faster than convex optimization techniques. Finally, a large complex engineering system is analyzed using the oracle and a cutting-plane algorithm. Analysis of the same system using the same computer hardware failed when employing convex optimization techniques.
Ph. D.

An evaluation is made of the potential fuel and financial savings possible when a small, autonomous diesel system sized to meet the demands of an individual, domestic consumer is adapted to include: (1) combined heat and power (CUP) generation. (2) wind turbine generation. (3) direct load control. The potential of these three areas is investigated by means of time-step simulation modelling on a microcomputer. Models are used to evaluate performance and a Net Present Value analysis used to assess costs. A cost/benefit analysis then enables those areas, or combination of areas, that facilitate the greatest savings to be identified. The modelling work is supported by experience gained from the following: (1) field study of the Lundy Island wind/diesel system. (2) laboratory testing of a small diesel generator set. (3) study of a diesel based CUP unit. (4) study of a diesel based direct load control system. (5) statistical analysis of data obtained from the long-term monitoring of a large number of individual household's electricity consumption. Rather than consider the consumer's electrical demand in isolation, a more flexible approach is adopted, with consumer demand being regarded as the sum of primarily two components: a small, electricity demand for essential services and a large, reschedulable demand for heating/cooling. The results of the study indicate that: (1) operating a diesel set in a CUP mode is the best strategy for both financial and fuel savings. A simple retrofit enables overall conversion efficiencies to be increased from 25% to 60%, or greater, at little cost. (2) wind turbine generation in association with direct load control is a most effective combination. (3) A combination of both the above areas enables greatest overall financial savings, in favourable winds resulting in unit energy costs around 20% of those of diesel only operation.

The United Nations (UN) project "Sustainable energy for all" sets three ambitious objectives to favor a sustainable development and to limit climate change: - Universal access to modern energy services. Electricity is currently not available for 1.3 billion people and the global energy demand is expected to grow of about 35% within 2040, due to the increasing world population and the expanding economies - Double the global rate of improvement in energy efficiency - Double the share of renewable energy sources (RESs) in the global energy mix In addition, according to the climate scenario assessed in the fifth assessment report (AR5) of the International Panel on Climate Change (IPCC), the prevention of undesirable climate effects requires a 40-70% reduction of greenhouse gas (GHG) emissions, compared with 2010 levels, by mid-century, and to near-zero by the end of this century (IPCC, 2014). The achievement of such objectives requires and encourages the spread of RESs in the global energy mix, gradually replacing depleting and polluting energy sources based on fossil fuels, which still have the main incidence on the energy sector. RESs already play a major role in several countries, due to the technological development and the increasing market competitiveness, and the world renewable power capacity reached 22.1% in 2013, showing an increasing trend in 2014 (REN, 2014). However, supporting policies, robust investments from the private sector and efforts from the scientific community are still crucial to demonstrate the technical and economic sustainability and effectiveness of RESs, helping their large-scale diffusion. Starting from such a background, this Ph.D dissertation focuses on the study, design and development of methods and tools for the optimization and enhancement of renewable energy technologies and their effective integration with energy storage solutions and traditional energy sources powered by fossil fuels (hybrid energy systems). The analysis of the major literature and the different scenarios and perspectives of RESs in the national and international contexts have shown that their economic sustainability, and then their diffusion, is closely connected to a number of technical, economic/financial and geographical parameters. Such parameters are the input of the analytic models developed for the techno-economic design of photovoltaic (PV) plants and small wind turbines (SWTs) and applied to the economic feasibility study, through multi-scenario analysis, of such systems in some of the main European Union (EU) Countries. Among the obtained results, the self-consumption of the produced energy plays a crucial role in the economic viability of SWTs and PV plants and, particularly, after the partial or total cut of incentives and uncertainties related to supporting policies within the EU context. The study of the energy demand profile of a specific user and the adoption of battery energy storage (BES) systems have been identified as effective strategies to increase the energy self-consumption contribution. Such aspects have led to the development of an analytic model for the techno-economic design of a grid connected hybrid energy system (HES), integrating a PV plant and a BES system (grid connected PV-BES HES). The economic profitability of the grid connected PV-BES HES, evaluated for a real case study, is comparable with PV plants without storage in case of a significant gap between the cost of energy purchased from the grid and the price of energy sold to the grid, but high BES system costs due to the initial investment and the maintenance activities and the eventual presence of incentives for the energy sold to the grid can make the investment not particularly attractive. Thus, the focus has shifted to the techno-economic analysis of off-grid HES to meet the energy demand of users in remote areas. In this context, BES systems have a significant role in the operation and management of the system, in addition to the storage of exceeding energy produced by the intermittent and variable RESs. The analysis has also been strengthened by an industrial application with the aim to configure, test and install two off-grid HESs to meet the energy demand of a remote village and a telecommunication system. In parallel, two experimental activities in the context of solar concentrating technology, a promising and not fully developed technology, have been carried out. The former activity deals with the design, development and field test of a Fresnel lens pilot-scale solar concentrating prototype for the PV energy distributed generation, through multi-junction solar cells, and the parallel low temperature heat recovery (micro-cogeneration CPV/T system). The latter activity deals with the development of a low cost thermal energy (TES) storage prototype for concentrating solar power (CSP) plants. TES systems show a great potential in the CSP plants profitability since they can overcome the intermittent nature of sunlight and increase the capacity factor of the solar thermal power plant. Concluding, the present Ph.D dissertation describes effective methods and tools for the optimization and enhancement of RESs. The obtained results, showing their critical issues and potential, aim to contribute to their diffusion and favor a sustainable development
Il progetto delle Nazioni Unite "Sustainable energy for all" ha fissato tre obiettivi ambiziosi per favorire uno sviluppo sostenibile e limitare l'impatto del cambiamento climatico: - Accesso universale a moderni servizi elettrici. Tali servizi sono attualmente indisponibili per circa 1.3 miliardi di persone ed è previsto un aumento del 40% della domanda globale di energia elettrica entro il 2040, a causa dell'incremento della popolazione mondiale e delle economie in crescita nei paesi in via di sviluppo - Raddoppio del tasso globale di miglioramento dell'efficienza energetica - Raddoppio del contributo di fonti di tipo rinnovabile nel mix energetico globale Inoltre, lo scenario climatico proposto nel "fifth assessment report (AR5)" redatto da "International Panel on Climate Change (IPCC)" stabilisce la necessità di ridurre l'emissione di gas ad effetto serra del 40-70%, rispetto ai valori registrati nel 2010, entro il 2050 ed eliminarli in modo quasi definitivo entro la fine del secolo con lo scopo di evitare effetti climatici indesiderati. Il raggiungimento di tali obiettivi richiede e incoraggia la diffusione di fonti energetiche rinnovabili (FER) all'interno del mix energetico globale, rimpiazzando gradualmente le fonti di energia convenzionali basate su combustibili fossili, inquinanti e in via di esaurimento, che hanno ancora l'incidenza principale nel settore energetico. A seguito nel loro sviluppo tecnologico e la crescente competitività nel mercato, le FER rivestono già un ruolo fondamentale nel mix energetico di numerose Nazioni ricoprendo il 22.1% del fabbisogno globale di energia nel 2013 e mostrando un andamento in rialzo nel 2014 (REN, 2014). Tuttavia, sono ancora cruciali politiche di supporto, ingenti investimenti privati e contributi della comunità scientifica per dimostrare l'efficacia e la sostenibilità tecnica ed economica delle FER e favorire, quindi, una loro diffusione in larga scala. In questo contesto, la seguente tesi di dottorato è rivolta allo studio, progettazione e sviluppo di metodi e strumenti per l'ottimizzazione e la valorizzazione di tecnologie energetiche rinnovabili e la loro integrazione efficace con fonti di produzione di energia convenzionali alimentate da combustibili fossili e sistemi di accumulo di energia (Sistemi energetici di tipo ibrido). I contributi scientifici disponibili in letteratura e l'analisi dei diversi scenari e delle prospettive delle FER nei vari contesti nazionali ed internazionali hanno dimostrato che la loro sostenibilità economica, e quindi la loro diffusione, è strettamente legata ad una serie di parametri tecnici, economico / finanziari e geografici. Tali parametri sono stati impiegati come input in due modelli analitici sviluppati per la progettazione tecnico-economica di impianti fotovoltaici (FV) e micro turbine eoliche e applicati per lo studio della loro fattibilità economica, attraverso analisi multi-scenario, in alcuni dei maggiori Paesi Europei. I risultati ottenuti hanno mostrato come l'autoconsumo dell'energia prodotta rivesta un ruolo fondamentale nella redditività economica dei citati impianti ed, in particolare, a seguito del taglio parziale o totale dei sistemi di incentivazione e l'incertezza attorno alle politiche di supporto all'interno del panorama Europeo. Lo studio specifico del profilo di domanda elettrica delle utenze e l'impiego di sistemi di accumulo di energia sono stati identificati come strategie efficaci al fine di incrementare la quota di autoconsumo. Tali considerazioni hanno portato allo sviluppo di un modello analitico utile alla progettazione tecnico-economica un sistema energetico ibrido connesso alla rete Nazionale integrante un impianto FV e un sistema di accumulo a batterie. La redditività del sistema, valutata su un caso reale, risulta comparabile a un impianto fotovoltaico privo di batterie in caso di un gap significativo tra il costo dell'energia elettrica acquistata dalla rete e il prezzo di vendita dell'energia elettrica ceduta in rete. Tuttavia, gli elevati costi dovuti all'acquisto iniziale e alle attività di manutenzione, e l'eventuale incentivazione sulla vendita dell'energia in rete, non rendono l'investimento particolarmente attrattivo per impianti connessi alla rete. L'attenzione si è quindi rivolta all'analisi tecnico-economica di sistemi energetici ibridi non connessi alla rete, comunemente definiti in isola o off-grid, per soddisfare il fabbisogno energetico di utenti in area remote e quindi prive di allaccio a una rete elettrica. In tali sistemi, i sistemi di accumulo a batterie, oltre alla capacità di accumulo dell'energia prodotta in eccesso variabili e intermittenti FER, hanno funzioni fondamentali nella gestione del sistema stesso. L'attività è stata anche rafforzata da un'applicazione industriale per la configurazione, test e installazione di due sistemi energetici ibridi in isola impiegati per soddisfare il fabbisogno energetico di un villaggio e di un sistema di telecomunicazione situati in aree remote. In parallelo, sono state svolte due attività sperimentali applicate alla promettente, ma non ancora completamente sviluppata a livello industriale, tecnologia solare a concentrazione. La prima attività riguarda la progettazione, sviluppo e test sperimentali di un prototipo in scala ridotta di concentratore solare a lenti di Fresnel per la produzione distribuita di energia elettrica, mediante l'uso di celle fotovoltaiche multi giunzione, ed energia termica a bassa temperatura, tramite un sistema di recupero termico. La seconda attività concerne lo sviluppo e test sperimentali di un prototipo di sistema di accumulo termico per impianti termodinamici alimentati da sistemi a concentrazione solare. Il sistema di accumulo consente di compensare la natura intermittente e variabile della fonte solare incrementando le ore di funzionamento dell'impianto termodinamico con i conseguenti benefici economici. Concludendo, la presente tesi di dottorato include la descrizione di metodi e strumenti per l'ottimizzazione e valorizzazione delle FER. I risultati evidenziano le criticità e potenzialità dei sistemi studiati con lo scopo di contribuire a una loro diffusione e favorire uno sviluppo sostenibile

碩士
聖約翰科技大學
電機工程系碩士在職專班
98
This study is to use the Visual Basic programming software, with various types of sensors for alternative comparison, research and development of the replacement of expensive research equipment, such as the use of proximity switches and tachometer head replacement anemometer, using the angle sensor alternative wind meter, digital meter and by Modbus transmission interface, the generation of small wind power system conditions and wind conditions to monitor the situation and record data. The research and development of the monitoring program the number of bits directly from the header extraction records, not through the data acquisition or data capture device to capture wind power generation system of information, and save them for the information form, as the system power data analysis and wind conditions query expansion and maintenance of the system is very convenient, and can serve as multi-function power monitor and capture data recording equipment to use

碩士
國立臺北科技大學
電機工程系研究所
99
To find an optimal operational point which can maximize wind energy output from the small wind turbine and provide favorable condition for batteries and loads, the research falls into two categories: the performance of the wind turbine generator and the parameters monitoring in both small wind turbines and wind electric systems. Since the wind power output relies on variable parameters, i.e. wind speed, the characteristic of turbines and the performance of the generator, we need more detailed information to make sure wind turbine working properly before to connect into the grid system. For this purpose, we include both smart grid system and the micro grid system in parallel with the small wind electric system, it not only establishes precise parameters but also collects information from the small wind electric system, to ensure enough wind energy to operate the wind turbine generator at a stable condition. On micro grid system, we use a lead-acid car battery as a power storage media to connect the small wind electric system. In order to get the correct performance of our 3kW synchronous wind generator, we set up a test platform to observe the voltage and current variations in both of different loads and different rotational speeds. Furthermore, in order to get the detailed information from the nature wind, we use the microchip which is processing unit of smart grid system to collect and compute the data from the measurement devices. The calculation results will be delivered to the remote host, therefore the operator can utilize these information to control and adjust the wind turbine system. With this data we finally establish a small wind electric system’s fuzzy archives which use fuzzy control method to find the optimal operation point. At this operation point, the wind power output can be maximized in various wind speeds, and the suitable condition for batteries and loads also can be reached.

碩士
南台科技大學
電機工程系
97
This thesis aimed to develop a small wind generation system which can be connected with the Grid-Operation the maximum power points tracking and the islanding detection. First, the system used an AC-DC converter to transfer the wind generator’s three phase output voltage to a stable DC voltage. The DC-DC converter stepped up the AC-DC converter output voltage, and injected power to the Grid by the DC-AC converter. The wind generator’s maximum power points were drifted by external effects . This thesis proposed a technique of maximum power points tracking. It was adjusting the input current command from the DC-AC converter and feedback output voltage of the AC-DC converter to achieve maximum power points. When the wind generator is connected to the Grid operation, the DC-AC converter need to pay attention to synchronous operation to Grid, and the islanding detection is important. This thesis proposed an improved method to detect islanding phenomenon, and improved non-detection zone of passive methods and Slip Mode Frequency Shift method (SMS).

碩士
明道大學
光電暨能源工程學系碩士班
100
Increase in the power efficiency of a small vertical-axis wind turbine (VAWT) elevates its potential that compares with a horizontal-axis wind turbine (HAWT). The power efficiency depends on the power coefficient of the wind turbine, the efficiency of the generator, the loss of the control circuits, and the algorithm of the optimal control. A good turbine has an airfoil with a high lift coefficient and is constructed by composite material to increase the power and to decrease the mass of the turbine. Besides, a generator having two windings keeps high efficiency at a lot of rotational speeds. To maximize the electricity output of the wind turbine system, this thesis used a straight wing non-articulated VAWT having the airfoils NACA3418 and NACA0018 and directly coupled a permanent magnet synchronous generator having 1kW winding and 3kW winding with the turbine as a 4kW wind power system. Meanwhile, a back to back voltage source converter controls the operation of the generator. A maximum power point tracking adapts the wind turbine so that it gives its best performance. The maximum efficiency of the wind power system is 0.272 through field tests. The results demonstrate that the 4kW small VAWT system has the same potential as the small HAWT.

碩士
國立聯合大學
電機工程學系碩士班
99
Small wind turbine generator has the disadvantages of low efficiency, vibration and acoustic noise by using conventional boost-based driver. The maximum power point tracking (MPPT) precision and response speed is also a critical problem in fast wind speed variation region. The braking and constant power control in high speed region raises the reliability problem, too. To cope with these problems, this thesis proposes a variable speed three-phase inverter-based drive for PMSG wind turbine generator. Due to sinusoidal and continuous conduction mode current the low efficiency, vibration and acoustic noise problems is alleviated. A fast MPPT method and an operating point deviation approach to reduce the requirement of resistor braking are presented along with the constant speed control. This thesis also develops a grid-connected inverter, through which the wind power can feed to the grid with low distorted and three-phase balanced manner. A 5kW prototype system is designed and implemented, the effectiveness of the proposed methods is confirmed with some simulation and experimental results.

碩士
建國科技大學
自動化工程系暨機電光系統研究所
97
This research aims to discuss the power generation performance of small capacity wind energy system. A blow-down open-type wind tunnel was specifically designed for the small capacity wind turbine generator according to experimental design, and the characteristics of wind turbine generator were tested using the velocities generated by the wind tunnel, and finally the test data was analyzed and discussed. With the measurement method of CNS7779 standard, a hot-wire anemometer was used to measure the wind velocity of the test section at outlet of wind tunnel, showing that the mean velocity ranged between 1.7 ~ 9.1 m/s. The experiment found that, the power of small capacity wind turbine generator would increase exponentially with the growing wind velocity. When the wind velocity is 4.6 m/s, the optimum wind energy conversion efficiency is about 16.86 Watt; the wind power coefficient ( ) is evaluated as 0.42, and the number of wind turbine generator’s impeller revolution is approximate 390 rpm. This study also found that, the rotation speed of wind turbine generator’s impeller would generate braking action with the reduction of system impedance. When the wind turbine generator is operated stably at the wind velocity of 6.22 m/s, the rotation speed of impeller is 488 rpm. When the system impedance declines gradually to 4.5 Ω, the rotation speed would slow down to about 350 rpm. On the whole, six-blades resistance wind turbine generator has an efficiency 10 ~ 20 % higher than conventional multiple-blades one. The monitoring system, experimental method and results here to can provide necessary concept and data for experimental analysis of small capacity wind turbine generator in the future.

Thesis (M.S.)--University of Nebraska-Lincoln, 2010.
Title from title screen (site viewed April 22, 2010). PDF text: v, 67 p. : col. ill. Publication: Electrical Engineering Theses and Dissertations. Includes bibliographical references.

碩士
國立宜蘭大學
機械與機電工程學系碩士班
97
Wind turbine generators are divided into two types - horizontal axis wind turbine generators and vertical axis wind turbine generators. Having been in use longer, the horizontal axis wind turbine generators are better developed and highly efficient. They are presently the most commonly used as well. However, because Taiwan is so crowded, the wind’s direction is unstable and the wind’s speed is usually low, thus making the horizontal axis wind turbine generators unsuitable for use in Taiwan cities. The vertical axis wind turbine generators are more suitable for these cities and have become a focal point of development in recent years. In the related references, most of the research focused on different areas of analysis, such as the design of the turbine blades, the efficiency of the rotor, the design of the generator, or the design of the structures, separately. Designing the wind turbine generator as a whole system was never considered, such as matching the most powerful generator with the turbine blades. This thesis is directed towards designing a completely integrated set of small-scale vertical axis wind turbine generator system that are suitable for the cities in Taiwan. ANSYS CFX was utilized to simulate the dynamics of turbine blades. The characteristics of the rotor, such as the output power under various rotational speeds to produce the maximum efficiency, were then obtained. According to these results, the selected generator was chosen since it would produce the maximum output of power for the system. Finally, the structures were designed to complete the whole system of a small-scale vertical axis wind turbine generator.

碩士
清雲科技大學
電機工程所
98
This thesis a small-scaled vertical axis wind power generation system was development. In the wind turbine side, the maximum power point tracking method was adopted to control the DC/DC boost chopper to achieve optimum maximum power output and enhance conversion efficiency. In the batteries side, a boost dc chopper was used to get the maximum power association with variation wind speed from the wind power generation system and supply power to batteries charge. Finally, DC power can be transformed into AC power by a single phase full-bridge inverter. The voltage source voltage control method was used to control the inverter for independent system. In this thesis, the artificial wind tunnel was used to measure the characteristic curve of wind turbines to build the mathematical models. Then, a high-performance, low-cost digital signal processor (DSP,TMS320LF2407A) was adopted to implement the system for reducing the circuit components and cost. Experimental results for 300W small-scaled vertical axis wind power system. The rated output voltage is 110V, the frequency is 60Hz.

碩士
南台科技大學
機械工程系
92
In order to meet the governmental development trend of the pure green energy and establish the school characteristic of the public facility demonstration system, the Southern Taiwan University of Technology installs a small wind power system in 2002. The main purpose for this study is to define the electricity transfer efficiency of the wind power generator. The monitoring software design for the system was written by using the LabVIEW. Then use the record data from monitoring the strategy locations in the circuit system, to calculate the system electricity generator efficiency. In addition, to estimate load demand, we will compare the inverter (DC/AC) with commutator (EZ-WIRE) in performance of their transform loses. The elevation angle ψ of the wind turbine can help to decelerate the rotor of the generator in typhoon day. Moreover in order to research the relation between the elevation angle of the wind turbine and the aerodynamic flow field around the blades, a digital particle image velocimetry (DPIV) system has been developed to measure instantaneous and ensemble-averaged flow fields around one two-dimensional blade. The flow phenomenon also utilized CFD software-FLUENT to carry out the numerical results for verifying the experimental data. It disclose that the vortex reaction in the downstream of the blade will be the main role for causing the elevation of the wind turbine.

碩士
淡江大學
航空太空工程學系碩士班
99
This thesis is concerned with the research and development of a small horizontal-axis wind turbine system for moving vehicles. Specifically, this study investigates the characteristics matching problems between the rotor blade and generator, and develops a generator output control system using a micro-controller. The characteristics of some available generators are tested using a generator test bench. These generators are combined with the existing rotor blades to evaluate the matching availability. The controller designed of this system uses a microchip PIC16F917 to control the core through the planning and controlling software, with the boost and buck converter module circuit, to achieve objectives of maximum power tracking, charging control and generator overload protection. The design of the controller system from the study, applying to constant voltage of 13V for providing lead-acid battery to charge and provides 12V and 5V USB-type connector for DC electricity outputs, by using experiment and implementation to test and verify feasibility. When installing the wind turbine in vehicles, the wind turbine starts generating electricity with vehicle moving, and providing battery charge ability is able to extend the endurance of electrical vehicles. The 12V electricity output can be used to electronics, while the 5V USB-type electricity output can be used for charging the cell phone, led light, and so on. These enhance the usefulness and convenience of small wind turbines to achieve the goal of green energy saving.

碩士
中原大學
機械工程研究所
101
The main objective of this paper is to use a number of measurement sensors that efficiently measure significant properties of the wind turbine. All the information is transmitted by wireless network to monitor the status of the small wind turbine generators. The monitoring data contain wind speed and wind direction of the external environment, temperature and humidity, speed and steering angle as well as level of the wind turbine generators, and so on. In addition, the internal state of the generator can be monitored by accelerometer and temperature sensor, and a set of noise sensors are implemented to detect the noise level. All of the monitoring data, for example the wind speed, the cut-in wind speed, the rated wind speed, and the extreme speed, can provide enough information that verify the performance of the wind turbine generator. In comparison with the measurement data, the related designed parameters can be modified in order to improve the design procedures and increase the reliability and steadiness as well as safety of the entire system.

碩士
國立臺灣科技大學
電機工程系
104
This thesis presents the analysis and implementation of three-phase permanent-magnet synchronous generator (PMSG) and its drive system, including horizontal wind turbine, permanent-magnet synchronous machine, bidirectional power converter for motor as well as generator modes of operation. Finite element analysis (FEA) software Maxwell/2D is used to determine PMSG's geometry for physical build-up through the comparison of the total harmonic distortions (THD) of induced electro-motive-force for different pole numbers as well as magnet pole-arc to pole-pitch ratios. Three-phase three-leg bidirectional power converter using six-step square-wave pulse-width modulation is proposed to drive the synchronous machine. Specifically, in motor mode, speed closed-loop control is given to drive permanent-magnet synchronous motor. While in the generator mode, current closed-loop and maximum power point tracking controls are introduced for PMSG to yield optimum phase current commands corresponding to various wind speeds. Futhermore, digital Hall-effect sensors are used to detect the rotational speed with low cost. As for the wind turbine blades, three-blade horizontal wind turbine, which has the advantages of high tip-speed ratio and low pull-in torque, is proposed to result in the expected rotational speed and generate the power in the low wind speed environment. FEA shows the no-load voltage of this machine under generator mode at 180 rpm is 11.51 V, and the THD is 1.46 %. The corresponding experimental results are 11.43 V and 1.60 %, respectively. Close agreement between analysis and measurement is obtained. In addition, the 32-bit digital signal processor, TMS320F28069, is adopted as the control core, and most of the control strategy is accomplished by software program. Experimental results show that under the motor mode, with the dc-link input voltage of 12 V , the motor can reach the rotational speed of 60 rpm and operate stably. Whereas, in generator mode, under the wind speed of 6 m/s, which is equivalent to the rotational speed of 160 rpm, generator phase current command of 1.8 A will yield output dc voltage, current and power of 20 V, 1.2 A and 24 W, respectively, with the constant battery charging current of 0.8 A. In short, both the simulated and experimental results verify the feasibility of the proposed system design and control strategy.

碩士
國立虎尾科技大學
機械與機電工程研究所
101
The purpose of this study is to construct an available small wind power system in the car, so we can recycle wind energy by using this equipment when driving the car. Cars using fossil fuel are facing critical challenging dioxide produced by combustion when driving the car is making green house effect increasingly serious. Therefore, it’s very important to design a vehicle that can be partly driven by alternative energy. The perspective of the study is to recycle wind energy when a car is moving and develop small wind power generator which can be used by car to be an assistant power source. We calculate the length of chord-length and rotation angle with aerodynamic of power generator and TRIZ; after the specification and the shape is decided, the blade can be produced by aluminum to demonstrate its at line and angle wing the technique of benchwork. Aluminum which has an advantage of high strength but light weight is widely used in automobile and aerospace machines. By integrating power generator, transmission equipment, and power adapter into transportation vehicles, we can now convert the surrounded wind energy into electricity and store it so as to utilize it easily at any time. With the actual of relative wind speed data recorded when the car is driving, total energy production of blade and the power system is known.

Approaching problems with global warming due to the use of fossil fuels, means that new system solutions have to be investigated. This report investigates the possibility to expand an existing photovoltaic system with a wind turbine generator to simplify the expansion of renewable energy sources. Through an extensive literature study and simulation in SIMULINK the result has been developed and tested. It shows that it is possible to connect a wind turbine generator to the same inverter as the PV-modules if no MPPT algorithm for the PV-modules is integrated. To protect the inverter a dump load has to be connected. Because of the complexity a DC-coupled system brings, AC-coupling is advised when expanding PV-modules with a WTG. The optimal wind turbine is considered to be a permanent magnet synchronous generator connected to the AC-bus through a full-effect inverter. The turbine should be chosen according to the intended location based on wind conditions and desired energy production.

碩士
義守大學
電子工程學系碩士班
99
As technology advances, a variety of products facilitate the life consequentially. Increasingly consumed energy becomes a major issue today, and energy saving subject is widely discussed. At present, the problem is that a variety of energy-saving products are too expensive to be accepted by masses. Taking the public works as the started target is a good ideal. Among those public works, the street lighting is in the first place that consumed the most energy, and the LED street lighting becomes the first candidate for implementing energy saving device. The thermal dissipation of the LED lamp is a headache problem. On the other hand, if we can collect this thermic energy to transfer into wind energy to rotate small wind generator, a double benefit is been created. A small wind generator mounted on the LED thermal dissipation plate is studied in this thesis. Started from a conceptual design, a Venturi tube is used to guiding the thermic through the Venturi pipe, so the thermal flow can rotate the wind generator. To enhance the pipe function, an outer hood is designed to form a flow field to conduct the heated wind. During the day time, the sun energy can also be collected to form a thermal channel that also goes through the Venturi tube. During the evening and night, LED is powered on, the dispelled heat can easily flow through the pipe. The simulation tools, such as AutoCad, ANSYS and Fluent CFD simulation software, are used to analyze the flow of thermal energy and wind energy. The finished work can successfully catch the heat and wind energy. We hope the designed energy saving device can run smoothly night and day.

碩士
國立中興大學
生物產業機電工程學系所
101
Develop a windowless livestock buildings excess energy recycling - Small scale wind turbine system application prototype architecture in this study. In general, ventilation fan must be set at windowless livestock buildings. There a stable wind energy, the rear end of the ventilation fan. In this study, the wind turbines set at the rear of the ventilation fan. And set the wind guide and rectifying mechanism between the ventilation fan and wind turbine. This study established wind turbine control system mode with the battery used in lighting equipment. The internal control system designed to manage battery charge and discharge. The establishment of the control system, the use of electricity generated from wind turbines to the windowless livestock buildings lighting equipment.That approach to achieve the effect of energy recycling and reuse. This application prototype model of wind turbine system generating power for 55.5 W, in other words to produce 486 kWh of electricity per year and decreased by approximately 260 kg CO2e. In this study, not only to achieve the purpose of energy recovery and reuse, as well as practical work in carbon reduction.

碩士
國立高雄應用科技大學
電機工程系碩士班
94
This thesis presents the dynamic behavior of a wind-small hydro hybrid synchronous power generation system operating under normal and abnormal conditions. The components of the system were developed using Simulink together with SimPowerSystems and then employed to cater for the dynamic behavior of the systems, including hydraulic turbine prime mover model, wind turbine model, induction generator model, three-phase power transformer model, capacitor bank model, and static load model. Various operational modes were simulated for the system, and the simulation results showed that the system operated acceptably under those conditions and should be coincident with practical operations. The dynamic behavior studies for hybrid inductive power generation systems are essential for system planning, operation, and further expansion

碩士
中原大學
電機工程研究所
99
This report analyzes the differences of maximum power point tracking (MPPT) methods by using MATLAB simulations. Considering the small wind power system composed of a small wind turbine, permanent-magnet synchronous generator, three-phase full bridge rectifier, DC/DC converter, MPPT power controller, and load, we will find the problems for using traditional MPPT methods. Here the fuzzy logic control method as well as perturbation and observation method is utilized for the MPPT control under several cases with step, fixed, and variable speed wind. By the MATLAB simulation tests, the fuzzy logic control MPPT method is better than the perturbation and observation method.