Dissertations / Theses on the topic 'Photovoltaic power systems Design and construction'
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Liu, Guang. "A photovoltaic-powered pumping system." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30592.
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This thesis studies the optimal design for a photovoltaic-powered medium-head (30 meters) water pumping system, with the emphasis on improving the efficiency and reducing the maintenance requirements of the electrical subsystem. The reduction of maintenance requirements is realized by replacing the conventional brush-type permanent magnet dc motor with a brushless dc (BLDC) motor. Different BLDC motor control techniques such as position-sensorless operation, sinusoidal and trapezoidal excitations are investigated. The improvement in efficiency is achieved by maximizing the output power from the photovoltaic array and by minimizing the losses in various parts of the electrical sub-system. A microprocessor-based double-loop maximum power tracking scheme is developed for maximization of the photovoltaic array output power. Over 99% utilization factor is achieved for a typical clear day regardless of the season of the year. The system losses are minimized mainly by performing loss analysis and selecting most suitable switching topologies and switching components. Experimental results show that the combined converter-motor efficiency is comparable to those of high-efficiency brush-type dc motor systems.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Gurganus, Heath Alan. "Battery Energy Storage Systems to Mitigate the Variability of Photovoltaic Power Generation." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1495.
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Methods of generating renewable energy such as through solar photovoltaic (PV) cells and wind turbines offer great promise in terms of a reduced carbon footprint and overall impact on the environment. However, these methods also share the attribute of being highly stochastic, meaning they are variable in such a way that is difficult to forecast with sufficient accuracy. While solar power currently constitutes a small amount of generating potential in most regions, the cost of photovoltaics continues to decline and a trend has emerged to build larger PV plants than was once feasible. This has brought the matter of increased variability to the forefront of research in the industry. Energy storage has been proposed as a means of mitigating this increased variability -- and thus reducing the need to utilize traditional spinning reserves -- as well as offering auxiliary grid services such as peak-shifting and frequency control. This thesis addresses the feasibility of using electrochemical storage methods (i.e. batteries) to decrease the ramp rates of PV power plants. By building a simulation of a grid-connected PV array and a typical Battery Energy Storage System (BESS) in the NetLogo simulation environment, I have created a parameterized tool that can be tailored to describe almost any potential PV setup. This thesis describes the design and function of this model, and makes a case for the accuracy of its measurements by comparing its simulated output to that of well-documented real world sites. Finally, a set of recommendations for the design and operational parameters of such a system are then put forth based on the results of several experiments performed using this model.
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Ogaili, Hamid Hawi Kadham. "Measuring the Effect of Vegetated Roofs on the Performance of Photovoltaic Panels in Combined Systems." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2299.
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Recent studies suggest that integration of photovoltaic panels with green roofs may improve the performance of both. While vegetation may provide a benefit by reducing the net radiation load on the underside of the photovoltaic (PV) panels, it may also affect convective cooling of panels, and consequently, panel efficiency. Both effects likely diminish with the height of the PV panel above the roof, although placing PV panels too close to the vegetation increases the risk of the plants growing over the edges of, and shading the PV panel. There is a gap in the literature with respect to evaluating these competing effects. The present study aims to fill this gap.
Experiments were conducted over a two-month period during summer using two identical PV panels within an array of rooftop-mounted panels. These experiments were performed at two heights (18 cm and 24 cm) using three roofing types: white, black and green (vegetated). Results showed that the mean power output of the system in which the PV panel was mounted above a green roof was 1.2% and 0.8% higher than that of the PV-black roof and the PV-white roof at the 18 cm height. At the 24 cm height, the benefit of the green roof was slightly diminished with power output for the PV panel above a green roof being 1.0% and 0.7% higher than the black and white roof experiments, respectively. These power output results were consistent with measured variations in mean panel surface temperatures; the green roof systems were generally cooler by 1.5˚C to 3˚C. The panel surface mean heat transfer coefficients for the PV-green roof were generally 10 to 23% higher than for the white and black roof configurations, suggesting a mixing benefit associated with the roughness of the plant canopy. As expected, the results indicate that the best PV panel performance is obtained by locating the PV panel above a green roof. However, the relative benefits of the roof energy balance diminish with distance between the PV panel and the roof.
Moreover, the results of this study showed that the mean power output of the PV panel above the white roof was 0.7% and 0.44% higher than that of the PV panel above the black roof at 18 cm and 24 cm heights, respectively. The results of the power output differences in all the experiments were statistically significant at the 95% confidence interval (P < 0.01).
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Ropp, Michael Eugene. "Design issues for grid-connected photovoltaic systems." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13456.
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Carr, Anna J. "A detailed performance comparison of PV modules of different technologies and the implications for PV system design methods /." Access via Murdoch University Digital Theses Project, 2005. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050830.94641.
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Williams, Nathaniel John. "On the design and monitoring of photovoltaic systems for rural homes." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/1308.
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It is estimated that 1.6 billion people today live without access to electricity. Most of these people live in remote rural areas in developing countries. One economic solution to this problem is the deployment of small domestic photovoltaic (PV) systems called solar home systems (SHS). In order to improve the performance and reduce the life cycle cost of these systems, accurate monitoring data of real SHSs is required. To this end, two SHSs typical of those found in the field were designed and installed, one in a rural area of the Eastern Cape of South Africa and the other in the laboratory. Monitoring systems were designed to record energy ows in the system and important environmental parameters. A novel technique was developed to correct for measurement errors occurring during the utilization of pulse width modulation charge control techniques. These errors were found to be as large as 47.6 percent. Simulations show that correction techniques produce measurement errors that are up to 20 times smaller than uncorrected values, depending upon the operating conditions. As a tool to aid in the analysis of monitoring data, a PV performance model was developed. The model, used to predict the maximum power point (MPP) power of a PV array, was able to predict MPP energy production to within 0.2 percent over the course of three days. Monitoring data from the laboratory system shows that the largest sources of energy loss are charge control, module under performance relative to manufacturer specifications and operation of the PV array away from MPP. These accounted for losses of approximately 18-27 percent, 15 percent and 8-11 percent of rated PV energy under standard test conditions, respectively. Energy consumed by loads on the systems was less than 50 percent of rated PV energy for both the remote and laboratory systems. Performance ratios (PR) for the laboratory system ranged from 0.38 to 0.49 for the three monitoring periods. The remote system produced a PR of 0.46. In both systems the PV arrays appear to have been oversized. This was due to overestimation of the energy requirements of the loads on the systems. In the laboratory system, the loads consisting of three compact fluorescent lamps and one incandescent lamp, were used to simulate a typical SHS load pro le and collectively consumed only 85 percent of their rated power. The 8 predicted load profile for the remote system proved to be signi cantly overestimated. The results of the monitoring project demonstrate the importance of acquiring an accurate estimation of the energy demand from loads on the system. Overestimations result in over-sized arrays and energy lost to charge control while under-sized systems risk damaging system batteries and load shedding. Significant under-performance of the PV module used in the laboratory system, underlines the importance of measuring module IV curves and verifying manufacturer specifications before system deployment. It was also found that signi cant PV array performance gains could be obtained by the use of maximum power point tracking charge controllers. Increased PV array performance leads to smaller arrays and reduced system cost.
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Koran, Ahmed Mohammed. "Photovoltaic Source Simulators for Solar Power Conditioning Systems: Design Optimization, Modeling, and Control." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23681.
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This dissertation presents various systematic design techniques for photovoltaic (PV) source simulators to serve as a convenient tool for the dynamic performance evaluation of solar power conditioning systems and their maximum power point tracking algorithms. A well-designed PV source simulator should accurately emulate the static and the dynamic characteristic of actual PV generator. Four major design features should be adopted in any PV source simulator: (i) high power-stage efficiency, (ii) fast transient response-time, (iii) output impedance matching with actual PV generator, and (iv) precise reference generation technique. Throughout this research, two different PV source simulator systems are designed, modeled, and experimentally verified. The design of the first system focuses mainly on creating new reference generation techniques where the PV equivalent circuit is used to precisely generate the current-voltage reference curves. A novel technique is proposed and implemented with analog components to simplify the reference signal generator and to avoid computation time delays in digital controllers. A two-stage LC output filter is implemented with the switching power-stage to push the resonant frequency higher and thus allowing a higher control-loop bandwidth design while keeping the same switching ripple attenuation as in the conventional one-stage LC output filter. With typical control techniques, the output impedance of the proposed simulator did not match the closed-loop output impedance of actual PV generator due to the double resonant peaks of the two-stage LC output filter. Design procedures for both control and power-stage circuits are explained. Experimental results verify the steady-state and transient performance of the proposed PV source simulator at around 2.7 kW output.
The design concept of the first simulator system is enhanced with a new type of PV source simulator that incorporates the advantages of both analog and digital based simulators. This simulator is characterized with high power-stage efficiency and fast transient response-time. The proposed system includes a novel three-phase ac-dc dual boost rectifier cascaded with a three-phase dc-dc interleaved buck converter. The selected power-stage topology is highly reliable and efficient. Moreover, the multi-phase dc-dc converter helps improve system transient response-time though producing low output ripple, which makes it adequate for PV source simulators.
The simulator circuitry emulates precisely the static and the dynamic characteristic of actual PV generator under different environmental conditions including different irradiance and temperature levels. Additionally, the system allows for the creation of the partial shading effect on PV characteristic. This dissertation investigates the dynamic performance of commercial and non-commercial solar power conditioning systems using the proposed simulator in steady-state and transient conditions. Closed-loop output impedance of the proposed simulator is verified at different operating conditions. The impedance profile --magnitude and phase- matches the output impedance of actual PV generator closely. Mathematical modeling and experimental validation of the proposed system is thoroughly presented based on a 2.0 kW hardware prototype. The proposed simulator efficiency including the active-front-end rectifier and the converter stages at the maximum power point is 96.4%.
Ph. D.
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Levy, Michael Yehuda. "Design, experiment, and analysis of a photovoltaic absorbing medium with intermediate levels." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24703.
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Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Committee Chair: Honsberg, Christiana; Committee Co-Chair: Citrin, David; Committee Member: Doolittle, Alan; Committee Member: First, Phillip; Committee Member: Ralph, Stephen; Committee Member: Rohatgi, Ajeet
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Hiranvarodom, Somchai. "Design and analytical evaluation of stand-alone photovoltaic power systems for rural areas in Thailand." Thesis, Northumbria University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340072.
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Mahdavi, Sareh. "RF power amplifiers and MEMS varactors." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112576.
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This thesis is concerned with the design and implementation of radio frequency (RF) power amplifiers and micro-electromechanical systems---namely MEMS varactors. This is driven by the many wireless communication systems which are constantly moving towards increased integration, better signal quality, and longer battery life.The power amplifier consumes most of the power in a receiver/transmitter system (transceiver), and its output signal is directly transmitted by the antenna without further modification. Thus, optimizing the PA for low power consumption, increased linearity, and compact integration is highly desirable.
Micro-electromechanical systems enable new levels of performance in radio-frequency integrated circuits, which are not readily available via conventional IC technologies. They are good candidates to replace lossy, low Q-factor off-chip components, which have traditionally been used to implement matching networks or output resonator tanks in class AB, class F, or class E power amplifiers. The MEMS technologies also make possible the use of new architectures, with the possibility of flexible re-configurability and tunability for multi-band and/or multi-standard applications.
The major effort of this thesis is focused on the design and fabrication of an RF frequency class AB power amplifier in the SiGe BiCMOS 5HP technology, with the capability of being tuned with external MEMS varactors. The latter necessitated the exploration of wide-tuning range MEMS variable capacitors, with prototypes designed and fabricated in the Metal-MUMPS process.
An attempt is made to integrate the power amplifier chip and the MEMS die in the same package to provide active tuning of the power amplifier matching network, in order to keep the efficiency of the PA constant for different input power levels and load conditions.
Detailed simulation and measurement results for all circuits and MEMS devices are reported and discussed.
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Schuss, C. (Christian). "Measurement techniques and results aiding the design of photovoltaic energy harvesting systems." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526215914.
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Abstract This thesis presents measuring techniques as well as measured and simulated results with the aim of helping the design of photovoltaic energy harvesting systems. Therefore, cost-effective measurement setups were developed for collecting the amount of irradiation, for both stationary and moving photovoltaic (PV) installations. The impact of the time resolution of solar radiation data on estimating the available solar energy was investigated. For moving PV installations, the dynamics and the rate of changes in the available irradiation were studied in order to analyse the effects on maximum power point tracking (MPPT) algorithms. In addition, possibilities for harvesting PV energy in indoor environments were also investigated. The main contribution of this thesis is the effective testing of PV cells and complete PV panels: instead of measuring the characteristic I-V (Current-Voltage) response under strictly controlled artificial illumination, photovoltaics are simply biased externally. Then, with the help of synchronized thermography (ST), infrared (IR) images of the PV panel self-heating are recorded. In the obtained IR-images, defected areas are seen as cold spots, since they are not biased by the external power supply. From the calculated temperature variations, the size of the defect area can be calculated and, thus, the loss in output power can be estimated. The method is shown to work both with and without glass encapsulationTiivistelmä Tämä työ esittelee mittaustekniikoita ja mitattuja ja simuloituja tuloksia aurinkoenergian keruujärjestelmien suunnittelun avuksi. Työtä varten kehitettiin kustannustehokas mittausjärjestelmä, jonka avulla arvioitiin aurinkoenergian määrää sekä stationaarisen että liikkuvan valokennon tapauksissa. Näiden lisäksi tutkittiin mittaustaajuuden vaikutusta arvioitaessa saatavilla olevan aurinkoenergian määrää. Liikkuvan PV (photovoltaic)-asennuksen avulla tutkittiin saatavilla olevan aurinkoenergian vaihtelun suuruutta ja nopeutta tarkoituksena analysoida näiden vaikutuksia käytettäviin MPPT-algoritmeihin. Tämä lisäksi tutkittiin myös valoenergian keruumahdollisuuksia sisätiloissa. Työn tärkein kontribuutio on valokennojen ja kokonaisten valopaneelien toiminnallisuuden testaamisen tehostaminen. Tyypillisesti PV:n toiminnallisuus varmistetaan tarkasti määritetyssä ympäristössä suoritetun I-V -ominaiskäyrämittauksen avulla. Tämän työn menetelmä on yksinkertaisesti biasoida PV:t ulkoisesti, minkä jälkeen ST (synchronized thermpgraphy) -kuvauksen avulla määritetään PV-paneelien itselämpenemistä kuvaavat infrapunakuvat. Paneelin vioittuneet alueet erottuvat IR-kuvissa kylminä alueina ulkoisen biasoinnin puuttuessa. IR-kuvista havaituista lämpötilavaihteluista on mahdollista määrittää vioittuneen alueen koko ja siten arvioida myös menetettyä lähtötehoa. Kyseisen metodin toimivuus osoitettiin niin lasikoteloiduilla kuin ilman sitä olevilla PV-paneeleilla
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Low, Yee Weng. "Techno-economic model for designing marine and offshore power generating systems." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/15868.
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Scherba, Adam. "Modeling the Impact of Roof Reflectivity, Integrated Photovoltaic Panels and Green Roof Systems on the Summertime Heat Island." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/246.
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This study presents the results of a modeling effort to explore the role that sustainable roofing technologies play in impacting the rooftop energy balance, and the resultant net sensible heat flux into the urban atmosphere with a focus on the summertime urban heat island. The model has been validated using data from a field experiment. Roofing technologies explored include control dark membrane roof, a highly reflective (cool) roof, a vegetated green roof, and photovoltaic panels elevated above various base roofs. Energy balance models were developed, validated with experimental measurements, and then used to estimate sensible fluxes in cities located in six climate zones across the US. To evaluate the impact on urban air temperatures, a mesoscale meteorological model was used. Sensible flux profiles calculated using a surface energy balance were used as inputs to the mesoscale model. Results for a 2-day period in Portland, OR are analyzed. Average findings indicate that the black roof and black roof with PV have the highest peak daily sensible flux to the environment, ranging from 331 to 405 W/m2. The addition of PV panels to a black roof had a negligible effect on the peak flux, but decreased the total flux by an average of 11%. Replacing a black roof with a white or green roof resulted in a substantial decrease in the total sensible flux. Results indicate that if a black membrane roof is replaced by a PV covered white or a PV covered green roof the corresponding reduction in total sensible flux is on the order of 50%. Mesoscale modeling results indicate peak daytime temperature reduction of approximately 1°C for both white and green roofs. However, there is a nighttime penalty on the order of 0.75°C for the green roof case, which has been attributed to the additional thermal storage of a green roof. Findings also reveal that the addition of PV panels to a roof has a nighttime cooling effect. This is most pronounced on a white roof, with magnitudes of 1°C. The methodology developed for this analysis provides a foundation for evaluating the relative impacts of roof design choices on the urban climate and should prove useful in guiding urban heat island mitigation efforts.
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Uluoglu, Arman. "Solar-hydrogen Stand-alone Power System Design And Simulations." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611884/index.pdf.
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In this thesis, solar-hydrogen Stand-Alone Power System (SAPS) which is planned to be built for the emergency room of a hospital is designed. The system provides continuous, off-grid electricity during the whole period of a year without any external electrical power supply. The system consists of Photovoltaic (PV) panels, Proton Exchange Membrane (PEM) based electrolyzers, PEM based fuel cells, hydrogen tanks, batteries, a control mechanism and auxiliary equipments such as DC/AC converters, water pump, pipes and hydrogen dryers. The aim of this work is to investigate the optimal system configuration and component sizing which yield to high performance and low cost for different user needs and control strategies. TRNSYS commercial software is used for the overall system design and simulations.
Numerical models of the PV panels, the control mechanism and the PEM electrolyzers are developed by using theoretical and experimental data and the models are integrated into TRNSYS. Overall system models include user-defined components as well as the default software components. The electricity need of the emergency room without any shortage is supplied directly from the PV panels or by the help of the batteries and the fuel cells when the solar energy is not enough. The pressure level in the hydrogen tanks and the overall system efficiency are selected as the key design parameters. The major component parameters and various control strategies affecting the hydrogen tank pressure and the system efficiency are analyzed and the results are presented.
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Kamanzi, Janvier. "Thermal electric solar power conversion panel development." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2527.
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Thesis (DTech (Engineering))--Cape Peninsula University of Technology, 2017.The world has been experiencing energy-related problems following pressuring energy demands which go along with the global economy growth. These problems can be phrased in three paradoxical statements: Firstly, in spite of a massive and costless solar energy, global unprecedented energy crisis has prevailed, resulting in skyrocketing costs. Secondly, though the sun releases a clean energy, yet conventional plants are mainly being run on unclean energy sources despite their part in the climate changes and global warming. Thirdly, while a negligible percentage of the solar energy is used for power generation purposes, it is not optimally exploited since more than its half is wasted in the form of heat which contributes to lowering efficiency of solar cells and causes their premature degradation and anticipated ageing. The research is geared at addressing the issue related to unsatisfactory efficiencies and anticipated ageing of solar modules. The methodology adopted to achieve the research aim consisted of a literature survey which in turn inspired the devising of a high-efficiency novel thermal electric solar power panel. Through an in-depth overview, the literature survey outlined the rationale of the research interest, factors affecting the performance of PVs as well as existing strategies towards addressing spotted shortcomings. While photovoltaic (PV) panels could be identified as the most reliable platform for sunlight-to-electricity conversion, they exhibit a shortcoming in terms of following the sun so as to maximize exposure to sunlight which negatively affects PVs’ efficiencies in one hand. On the other hand, the inability of solar cells to reflect the unusable heat energy present in the sunlight poses as a lifespan threat. Strategies and techniques in place to track the sun and keep PVs in nominal operational temperatures were therefore reviewed.
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Krygowski, Thomas Wendell. "A novel simultaneous diffusion technology for low-cost, high-efficiency silicon solar cells." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/22973.
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Ginn, James. "Broadband Rectifying Antenna Design for Low Power Applications." Honors in the Major Thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/710.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucfBachelors
Engineering and Computer Science
Electrical Engineering
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Ferris, Jennifer. "The Design, Implementation, Assessment, and Evaluation of a Power Systems Protection Laboratory Curriculum." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1623.
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Over the last the last three decades, there has been a significant and documented decrease of power engineering curriculum within U.S. electrical engineering programs. Development of lifelong learners capable of critical and independent thinking is required to replace the large number of upcoming retirees from the industry and to prepare for the engineering challenges new technologies, laws and regulations are bringing to the electrical power system. In response to these challenges, Portland State University redesigned its BSEE and MSECE power engineering programs in order to create a launching pad for successful power engineering careers. A course series on power system protection is part of the requisite curriculum for both programs. Due to the complex and applied nature of this subject, the course features a laboratory component.
This thesis addresses the pedagogical and engineering problems associated with developing power systems protection laboratory curriculum. Laboratory equipment and curriculum design were guided by outcomes defined by ABET EC2000 and specific outcomes defined for the laboratory that we adopted from research commissioned by ABET. Hands-on experience with industry equipment and software enhances classroom-based course curriculum, expanding student understanding of the complexities of the subject of power system protection. Intergroup and intragroup communication is required in the laboratory, as are weekly written reports synthesizing subject material and experimental results. The outcomes of the laboratory are evaluated through a combination of grading rubrics and student participation in individual laboratory assignment surveys.
The laboratory is comprised of three stations consisting of electromechanical (EM) relays and digital relay equipment. The practical experience with industry standard relays types happens in concert with a software-based simulation program. There are three phases of development; Phase I includes the design of the physical laboratory and the procural, or design and fabrication, of necessary equipment. Phase II involves the teaching term of the laboratory and the active assessment. Phase III involves the design and specification of a model-scale laboratory, to be built in future terms, which will provide students with the ability to test power system protection equipment in a physically simulated environment. This model-scale system will also provide a platform for future expansions of the power system protection laboratory in terms of distance protection, generation control, phasor measurement units, and system control schemes.
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Liu, Xinghua, and 刘兴华. "Power system operation integrating clean energy and environmental considerations." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085866.
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Shen, Ming. "Distributed Solar Photovoltaic Grid Integration System : A Case Study for Performance." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/945.
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The needs to the sustainable development of electricity, energy efficiency improvement, and environment pollution reduction have favored the development of distributed generation (DG). But the problems come with increasing DG penetration in distribution networks. This thesis presents the Solar Energy Grid Integration System (SEGIS) Stage III project done by Portland General Electric (PGE), Advanced Energy, Sandia National Lab on a PGE selected distribution feeder. The feeder has six monitored commercial solar PV systems connected. The total power output from the PV systems has the potential to reach 30% of the feeder load. The author analyzes the performance of the solar feeder on both generation and voltage effects. As a project report, it introduced a new islanding detection done by other team members to give an islanding solution of future high penetration distribution networks. At last, the author describes micro-grid and grid support concepts in a SEGIS concept paper with some examples.
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Poon, Kai-yin Kenny, and 潘啟然. "An investigation on the application of nonlinear robust adaptive control theory in AC/DC power systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38898949.
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DeLucia, Dominic. "A Parametric Study on Power Variation for Model Wind Turbine Arrays." PDXScholar, 2013. http://pdxscholar.library.pdx.edu/open_access_etds/1120.
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This thesis presents the results of wind tunnel experiments performed for various model wind turbine arrays. The aim is to understand how siting affects power output. To optimize wind farm efficiency the experiments vary the parameters of the model wind turbines and the layout of the wind turbine array. The parameters include the alignment, height, spacing, and the rotational direction of the model wind turbines. These experiments employ mechanical torque sensors to simultaneously measure the torque and rotor angular velocity, which yields a direct measurement of the fluid mechanical power extracted by the turbine at multiple locations. For a 4 × 3 array, the power is calculated at the center turbine in each of the rows. Variations in wind farm efficiency ranging from 55% to 90% are observed between the 13 different layouts tested. Modifications to the layout of the wind turbine array clearly affects the power output of the wind turbines downstream. The results of such experiments highlight the importance of studying the relationship between wind farm layout and power output.
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Pham, Tien Ke. "Low-power, high-accuracy, and fast-tuning integrated continuous-time 450-KHz bandpass filter." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/13525.
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Mang, Xuesi. "Hardware and software control for the NASA EOS satellite power system testbed." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-05092009-040507/.
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Barnes, Lemuel Gregory III. "Voltage-source inverter output waveform compensation using adaptive intelligent control." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/39997.
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A single-layer neural network-based voltage compensation technique which generates minimum-distortion sinusoidal output voltages from a three-phase PWM inverter used for uninterruptible power supplies (UPS) is described. The proposed compensation technique is implemented in a microprocessor-based controller constructed in the stationary d-q frame where the controller sampling rate is twice the inverter switching frequency. The structure of a feed-forward artificial neural network connects network inputs and outputs through multiple linear or nonlinear
neuron models, and processes these input/output data associations in a
parallel distributed manner. Network inputs in the form of UPS load voltage commands and load current feedback are propagated forward in the network each controller sampling period generating the inverter output voltage commands, the network outputs, which are converted to three phase inverter switching Signals using the space vector PWM waveform generation process.Ph. D.
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Moore, Christopher Wayne. "Microfabricated Fuel Cells To Power Integrated Circuits." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7106.
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Microfabricated fuel cells have been designed and constructed on silicon integrated circuit wafers using many processes common in integrated circuit fabrication, including sputtering, polymer spin coating, reactive ion etching, and photolithography. Fuel delivery microchannels were made through the use of sacrificial polymers. The characteristics of different sacrificial polymers were studied to find the most suitable for this work. A polypropylene carbonate solution containing a photo-acid generator could be directly patterned with ultraviolet exposure and thermal decomposition. The material that would serve as the fuel cells proton exchange membrane (PEM) encapsulated the microchannels. Silicon dioxide deposited by plasma enhanced chemical vapor deposition (PECVD) at relatively low temperatures exhibited material properties that made it suitable as a thin-film PEM in these devices. By adding phosphorous to the silicon dioxide recipe during deposition, a phosphosilicate glass was formed that had an increased ionic conductivity. Various polymers were tested for use as the PEM or in combination with oxide to form a composite PEM. While it did not work well alone, using Nafion on top of the glass layer to form a dual-layer PEM greatly enhanced the fuel cell performance, including yield and long-term reliability. Platinum and platinum/ruthenium catalyst layers were sputter deposited. Experiments were performed to find a range of thicknesses that resulted in porous layers allowing contact between reactants, catalyst, and the PEM. When using the deposited glasses, multiple layers of catalyst could be deposited between thin layers of the electrolyte, resulting in higher catalyst loading while maintaining porosity. The current and power output were greatly improved with these additional catalyst layers.
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Nsumbu, Cassandra Daviane. "Development of a soft-core based power electronic conversion controller." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/2379.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2014.The application of digital control techniques has become dominant in power electronics owing to several advantages they present, when compared to analogue solutions. Their development is based on the use of microprocessors and microcontrollers, such as Application Specific Integrated Circuit (ASIC), Digital signal processors (DSP), Field Programmable Gate Arrays (FPGA), or a combination of these devices. This thesis presents an investigation of a soft-core based FPGA control system as a solution for power electronic applications. The aim was the development and implementation of a conversion controller, which purpose is to supply control inputs in the form of digital Pulse Width Modulation (PWM) signals, to a number of power electronic applications, such as single half and full bridge DC-DC converters, three phase and multicell inverters. The PWM control technique is achieved via their power semiconductor switching devices. These PWM control signals are necessary for the high frequency conversion of an analog input voltage (AC, DC or unregulated) to an analog output voltage of another level (AC or DC). This was intended to be achieved by exploiting and combining the advantages that FPGA and embedded processors provide such as high reconfigurability and multipurpose ability. This controller’s digital outputs, namely PWM switching signals, can be directly delivered to an analog signal amplification circuit to create an adequate voltage level before being processed by the converters’ switches.
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Poellabauer, Christian. "Q-Fabric: System Support for Continuous Online Quality Management." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-04082004-134256/unrestricted/poellabauer%5Fchristian%5F200405%5Fphd.pdf.
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Thesis (Ph. D.)--Computing, Georgia Institute of Technology, 2004.Pande, Santosh, Committee Member ; Pu, Calton, Committee Member ; Schwan, Karsten, Committee Chair ; Franke, Hubertus, Committee Member ; Eisenhauer, Greg, Committee Member. Vita. Includes bibliographical references (leaves 158-169).
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Lambert, Darcy Erin. "Nanostructured Extremely Thin Absorber (ETA) Hybrid Solar Cell Fabrication, Optimization, and Characterization." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/637.
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Traditional sources of electrical energy are finite and can produce significant pollution. Solar cells produce clean energy from incident sunlight, and will be an important part of our energy future. A new nanostructured extremely thin absorber solar cell with 0.98% power conversion efficiency and maximum external quantum efficiency of 61% at 650 nm has been fabricated and characterized. This solar cell is composed of a fluorine-doped tin oxide base layer, n-type aluminum doped zinc oxide nanowires, a cadmium selenide absorber layer, poly(3-hexylthiophene) as a p-type layer, and thermally evaporated gold as a back contact. Zinc oxide nanowire electrodeposition has been investigated for different electrical environments, and the role of a zinc oxide thin film layer has been established. Cadmium selenide nanoparticles have been produced and optimized in-house and compared to commercially produced nanoparticles. Argon plasma cleaning has been investigated as a method to improve electronic behavior at cadmium selenide interfaces. The thermal anneal process for cadmium selenide nanoparticles has been studied, and a laser anneal process has been investigated. It has been found that the most efficient solar cells in this study are produced with a zinc oxide thin film, zinc oxide nanowires grown under constant -1V bias between the substrate material and the anode, cadmium selenide nanoparticles purchased commercially and annealed for 24 hours in the presence of cadmium chloride, and high molecular weight poly(3-hexylthiophene) spin-coated in a nitrogen environment.
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Mukhopadhyay, Rajarshi. "Broadband and Low-Power Signal Generation Techniques for Multi-Band Reconfigurable Radios in Silicon-based Technologies." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14097.
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Wireless communication is witnessing tremendous growth with the proliferation of various standards covering wide, local, and personal area networks, which operate at different frequency bands. Future wireless terminals will not only need to support multiple standards, but also need to be multi-functional to keep pace with the demands of the consumers. For such an implementation, the local oscillator (LO) turns out to be the bottleneck, which must exhibit frequency agility by generating a very wide range of carrier frequencies in order to access all the specified communication standards.
This dissertation presents various design techniques to realize compact low-cost low-power and broadband oscillators in silicon-based technologies. The two most suitable techniques for broadband signal generation: (1) Use of widely tunable active inductor, and (2) Use of switched resonator have been thoroughly evaluated. A fully reconfigurable active inductor with a widely tunable feedback resistor has been proposed. Using the proposed tunable active inductor in a VCO generates frequency tuning ranges higher than 100%, and helps achieve the highest PFTN Figure-of-Merit among Si-based active inductor VCOs reported in literature till date. The large-signal non-linearity of the active inductor has been utilized to develop the first reported broadband harmonic active inductor-based VCO. The degradation of phase noise due to active inductors is partially solved by a noise optimization guideline for active inductors. Utilizing the low saturation voltage of HBT technologies and high-Q short line inductors seems to be very useful to reduce power consumption of cross-coupled VCOs while achieving low phase noise performance simultaneously.
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Fisher, Kate School of Photovoltaic & Renewable Energy Engineering UNSW. "The pitfalls of pit contacts: electroless metallization for c-Si solar cells." Awarded by:University of New South Wales. School of Photovoltaic and Renewable Energy Engineering, 2007. http://handle.unsw.edu.au/1959.4/29568.
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This thesis focuses on improving the adhesion of electroless metal layers plated to pit contacts in interdigitated, backside buried contact (IBBC) solar cells. In an electrolessly plated, pit contact IBBC cell, the contact grooves are replaced with lines of pits which are interconnected by the plated metal. It is shown, however, that electroless metal layers, plated by the standard IBBC plating sequence, are not adherent on pit contact IBBC solar cells. The cause of this adhesion problem is investigated by examining the adhesive properties of each of the metal layers in the electroless metallization sequence on planar test structures. This investigation reveals that Pd activation of heavily P diffused Si impedes Ni silicide growth and that, in the absence of a silicide at the Ni/Si interface, an electrolessly plated Cu layer will cause the underlying Ni layer to peel away from the substrate. It is also found that the Ni silicidation process itself intermittently causes the unreacted Ni to spontaneously peel away from the substrate. An electroless metallization sequence that results in thick, adhesive Cu deposits on planar < 100> surfaces is developed in this thesis. It is shown that this process leads to the formation of a Ni silicide on both n- and p- type, heavily diffused surfaces. Fully plated, pit contact IBBC solar cells were not able to be fabricated during the course of this work but it is reasonable to expect that the modified plating sequence developed in this work will result in the metal layers being adhesive on these cells.
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Li, Xiao. "Nonlinearity Analysis and Predistortion of 4G Wireless Communication Systems." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/992.
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The nonlinearity of RF power amplifiers (PA) is one of critical concerns for RF designers because it causes spectral regrowth related to in-band and out-of-band spurious emissions control in communication standards. Traditionally, RF power amplifiers must be backed off considerably from the peak of their power level in order to prevent spectral regrowth. The digital predistortion (DPD) technique is being widely used for compensation of the nonlinearity of RF power amplifiers, as the high power efficiency becomes increasely important in wireless communication systems.
However, the latest generations of communication systems, such as Wi-Fi, WiMAX, and LTE, using wider bandwidth have some additional memory distortion, other than the traditional memoryless distortion. The distortion caused by memory effect makes the traditional predistorter not precise any more for the PA linearization.
In this dissertation, the traditional prediction of 3rd order memoryless spectrum regrowth is applied to 4G communication signals in terms of the 3rd intercept point of PAs, based on the previous researches in Portland State University led by Professor Fu Li. Then, the spectrum regrowth prediction is extended to an arbitrarily high order with intercept points of an RF power amplifier. A simple predistortion method which enables direct calculation of the predistorter coefficients from the intercept points is also proposed.
Furthermore, the memory effect is taken into account for both PA modeling and predistortion. A simplified Hammerstein structure based method is proposed to analyze the nonlinear characteristic of PAs more precisely and completely. By applying the inverse structures of the PA model, the proposed predistorter corrects both the traditional memoryless nonlinear distortions and the memory effect that may exist in RF power amplifiers. The order of nonlinearity and depth of memory of a predistorter can be chosen from 0 to any arbitrarily high number. This increases the flexibility for designers to decide how to linearize power amplifier effectively and efficiently.
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Siddique, Nafiul Alam. "Spare Block Cache Architecture to Enable Low-Voltage Operation." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/216.
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Power consumption is a major concern for modern processors. Voltage scaling is one of the most effective mechanisms to reduce power consumption. However, voltage scaling is limited by large memory structures, such as caches, where many cells can fail at low voltage operation. As a result, voltage scaling is limited by a minimum voltage (Vccmin), below which the processor may not operate reliably. Researchers have proposed architectural mechanisms, error detection and correction techniques, and circuit solutions to allow the cache to operate reliably at low voltages. Architectural solutions reduce cache capacity at low voltages at the expense of logic complexity. Circuit solutions change the SRAM cell organization and have the disadvantage of reducing the cache capacity (for the same area) even when the system runs at a high voltage. Error detection and correction mechanisms use Error Correction Codes (ECC) codes to keep the cache operation reliable at low voltage, but have the disadvantage of increasing cache access time. In this thesis, we propose a novel architectural technique that uses spare cache blocks to back up a set-associative cache at low voltage. In our mechanism, we perform memory tests at low voltage to detect errors in all cache lines and tag them as faulty or fault-free. We have designed shifter and adder circuits for our architecture, and evaluated our design using the SimpleScalar simulator. We constructed a fault model for our design to find the cache set failure probability at low voltage. Our evaluation shows that, at 485mV, our designed cache operates with an equivalent bit failure probability to a conventional cache operating at 782mV. We have compared instructions per cycle (IPC), miss rates, and cache accesses of our design with a conventional cache operating at nominal voltage. We have also compared our cache performance with a cache using the previously proposed Bit-Fix mechanism. Our result show that our designed spare cache mechanism is 15% more area efficient compared to Bit-Fix. Our proposed approach provides a significant improvement in power and EPI (energy per instruction) over a conventional cache and Bit-Fix, at the expense of having lower performance at high voltage.
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Srirattana, Nuttapong. "High-Efficiency Linear RF Power Amplifiers Development." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6899.
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Next generation mobile communication systems require the use of linear RF power amplifier for higher data transmission rates. However, linear RF power amplifiers are inherently inefficient and usually require additional circuits or further system adjustments for better efficiency. This dissertation focuses on the development of new efficiency enhancement schemes for linear RF power amplifiers.
The multistage Doherty amplifier technique is proposed to improve the performance of linear RF power amplifiers operated in a low power level. This technique advances the original Doherty amplifier scheme by improving the efficiency at much lower power level. The proposed technique is supported by a new approach in device periphery calculation to reduce AM/AM distortion and a further improvement of linearity by the bias adaptation concept.
The device periphery adjustment technique for efficiency enhancement of power amplifier integrated circuits is also proposed in this work. The concept is clearly explained together with its implementation on CMOS and SiGe RF power amplifier designs. Furthermore, linearity improvement technique using the cancellation of nonlinear terms is proposed for the CMOS power amplifier in combination with the efficiency enhancement technique.
In addition to the efficiency enhancement of power amplifiers, a scalable large-signal MOSFET model using the modified BSIM3v3 approach is proposed. A new scalable substrate network model is developed to enhance the accuracy of the BSIM3v3 model in RF and microwave applications. The proposed model simplifies the modeling of substrate coupling effects in MOS transistor and provides great accuracy in both small-signal and large-signal performances.
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Gyoh, Louis Ember. "Design-management and planning for photovoltaic cladding systems within the UK construction industry : an optimal and systematic approach to procurement and installation of building integrated photovoltaics : an agenda for the 21st century." Thesis, University of Sheffield, 1999. http://etheses.whiterose.ac.uk/6035/.
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Sperlich, Roland. "Adaptive power amplifier linearization by digital pre-distortion with narrowband feedback using genetic algorithms." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-06232005-152633/.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.Leach, William M., Committee Member ; Sills, James A., Committee Member ; Kenney, J. Stevenson, Committee Chair ; Zhou, G. Tong, Committee Co-Chair ; Fenney, Robert K., Committee Member.
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Beviss-Challinor, Lauren Margaret. "Design, build and test a passive thermal system for a loft : a roof solar chimney application for South African weather conditions." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/348.
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Thesis (MEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2007.ENGLISH: The design, construction and testing of a passive thermal system, a roof solar chimney, for a loft is considered. Unlike conventional solar chimneys the solar collector is constructed from corrugated iron roof sheets with the aim that it can be integrated into existing buildings at a lower cost or used in low cost housing developments. The main objective of the study was to determine the feasibility of such low-cost design to regulate thermal conditions in a loft, that is heating the loft during winter and enhancing natural ventilation during summer, by carrying out an experimental and analytical study. The results obtained from the experimental study showed that for winter the solar chimney, having a channel width, depth and length of 0.7 m, 0.1 m and 1.8 m respectively and with a peal solar radiation of 850 W/m², heated the room air 5°C higher than the ambient temperature during the hottest periods of the day, which is only marginally better than a loft with conventional roof insulation. At night, it was found that reverse airflow occurred through the chimney, cooling the loft down to ambient temperature, due to radiation heat loss from the roof collector to the night sky. For summer operation, the experimental data showed that the chimney was able to maintain the loft at ambient temperature and the analytical study found that the chimney was able to enhance natural ventilation effectively, reaching air exchange rate of 6.6 per hour for the 4.6 m³ volume space. It was also found that the chimney’s performance dropped rapidly and significantly during periods of low solar radiation and at night. A sensitivity analysis illustrated that for both summer and winter operation, the size, tilt angle and absorptivity of the roof collector greatly effected the efficiency and mass flow rates of the system, agreeing well with other literature. These results prove that this low cost solar chimney cooling design was feasible to enhance natural ventilation mainly during hot summer conditions with high solar radiation. Compared to a loft with only conventional roof insulation, the chimney did not perform effectively during the winter to heat the loft up, meaning that winter operation for this specific design is not feasible. Possible improvements to the design include using construction materials with higher thermal capacities to retain heat energy and ensure continued operation during periods of low solar radiation, as well as using selective absorber coatings on the collector surface. It is recommended that further work on the project include the integration of these improvements into the present design and to use the findings obtained from the sensitivity analysis to improve system efficiencies. CFD analysis of the test-rig will be insightful as an additional means to validate and compare with the analytical and experimental data obtained in this report. With the continuation of these studies, this low-cost solar chimney design can be optimised, validated on a commercial scale and built into existing and new housing developments. Incorporating such a passive thermal device will aid homeowners in air regulation and thermal comfort of their living space as well as saving on energy requirements.
Sponsored by the Centre for Renewable and Sustainable Energy Studies, Stellenbosch University
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Pokorný, Marek. "Charakterizace vlastností fotovoltaického systému." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219073.
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The aim of this work is informed first about photovoltaics universally, works to inform the photovoltaic panels and complete plants. The work also includes instructions on how to implement PVP in accordance with law. Another part is the rough draft of the photovoltaic power 30 kWp, which can be placed on the house, computation and calculation of investment and them profitable investments to time. Design is made in two separate forms of the Fronius Solar and Sunny Design, their outputs are compared. The practical part of this work cooperates with the company SOLARTEC Ltd. for experimental measurements of the photovoltaic system and develop a methodology for setting the properties of real solar systems in operation from the measured data then stored in a database. These data further evaluate and compare the similar operating conditions. This data will show as the course of production of electricity during the typical day in percentage terms, depending on the incident irradiance, cell temperature, angle of incident radiation, etc. We can compare what it looks like an ideal day in terms of production of photovoltaic power, with the other days. Further are in work mentioned histograms achievement panel behind classical day and behind all - time investigation.
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Fangsuwannarak, Thipwan Photovoltaic & Renewable Energy Engineering UNSW. "Electronic and optical characterisations of silicon quantum dots and its applications in solar cells." 2007. http://handle.unsw.edu.au/1959.4/44340.
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In this thesis, the structural, optical and electrical properties of crystalline silicon quantum dots (SiQDs) are examined for application to silicon based tandem cells. The approach has been to concentrate on all silicon devices by taking advantage of quantum confinement in low-dimensional Si. RF magnetron co-sputtering provided the capability of creating superlattice structures in conjunction with high temperature annealing, to form Si nanocrystals in an oxide matrix. Structural techniques, including Fourier transform infrared spectroscopy (FTIR), micro-Raman spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Secondary ion mass spectroscopy (SIM) were employed to gather structural information about the SiQD/SiO2 SLs. The result combine presents that the packing density of Si QDs, correlated to the oxygen content of the silicon rich oxide layer can be control independently. The effect of Si nanocrystallite density on Raman scattering is investigated. The preliminary results present that a decrease in the oxygen content (x) results in an increased sharpness of the Strokes-mode peak of nanocrystalline Si, attributed to an increase in the proportion of crystalline Si because of the increased number of SiQDs. However the influence of the surface region on the crystallite core intensity scattering becomes dominant, when SiQD size diameter is very small (less than 3 nm). The present work shows that a decrease in x-content leading to an increase of the SiQD concentration, initially results in the enhancement of the lateral conductivity in the SiQD superlattice material. In this work, the Al contacting scheme, using a prolonged heat treatment technique at elevated temperature less than the eutectic point of Al and Si (577C) has been successfully applied to making Ohmic contacts on both SiQD SLs in oxide and nitride matrices. Activation energy (Ea) of SiQDs, extracted from a linear Arrhenius plot is investigated in the present work in order to expand the understanding of engineering electrical injection in laterally active paths. It is found that a lower barrier height of dielectric matrix influences to the lateral electron transport of the SiQDs in such dielectric matrix. PL results confirm that the band gap of surface oxidized SiQDs widens due to quantum confinement. The present results reveal that the strong peak (Q-peak) due to quantum confinement is more effective in the emission with increasing SiQD concentration. The surface oxide is believed to play an important role in the reduction of SiQD luminescence due to a trapped exiciton. It is concluded that SiQDs surface oxide accompanied by a SiO2 matrix may not provide a good passivation in very small SiQD size. However the energy band gap and conductivity of the SiQDs are tunablity, in the optimum range of SiQD size and concentration. This observation may be important for future nanoelectronics applications.
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Salve, Rima. "PV Based Converter with Integrated Battery Charger for DC Micro-Grid Applications." Thesis, 2014. http://hdl.handle.net/1805/6108.
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Indiana University-Purdue University Indianapolis (IUPUI)This thesis presents a converter topology for photovoltaic panels. This topology minimizes the number of switching devices used, thereby reducing power losses that arise from high frequency switching operations. The control strategy is implemented using a simple micro-controller that implements the proportional plus integral control. All the control loops are closed feedback loops hence minimizing error instantaneously and adjusting efficiently to system variations. The energy management between three components, namely, the photovoltaic panel, a battery and a DC link for a microgrid, is shown distributed over three modes. These modes are dependent on the irradiance from the sunlight. All three modes are simulated. The maximum power point tracking of the system plays a crucial role in this configuration, as it is one of the main challenges tackled by the control system. Various methods of MPPT are discussed, and the Perturb and Observe method is employed and is described in detail. Experimental results are shown for the maximum power point tracking of this system with a scaled down version of the panel's actual capability.
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Chou, Pin-Chun, and 周品君. "Design of Maximum-Power-Point-Tracking Control IC for Photovoltaic Power Systems." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/97065673520711207466.
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Wu, Wuu-Joung, and 吳武忠. "Study of Construction for Medium and Large Scale Solar Photovoltaic Power Generation Systems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/e3cgk8.
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碩士國立臺北科技大學
新能源電控產業碩士專班
101
High contemporary oil prices have retarded conventional coal-fire and fossil fuel power generation. Compared with numerous alternative energy sources, solar photovoltaic power generation demonstrates developmental advantages. After evaluating various alternative energy sources from the perspectives of economic, energy-saving, maintenance, and environmentally friendly factors, solar photovoltaic power generation systems show the most developmental potential because of its lack of rotational components, ease of operation, little maintenance requirement, and zero carbon dioxide emissions. To optimize solar photovoltaic power generation systems based on the aforementioned perspectives, relevant information regarding medium- and large-scale systems was collected. In this study, the system optimization planning, design, and construction methods were investigated by analyzing relevant information and data such as construction processes, engineering planning and design, construction contracting, supervision and inspection, warranty and maintenance, and system operating conditions. A convenient, simple, and flexible management system was created to enhance the overall reliability and maintainability of the system, reduce the developmental costs of techniques, and retain the expandability and advancement of the system. This study is expected to benefit the construction of medium- and large-scale solar photovoltaic power generation systems, facilitating optimized supervisory control systems and practical applications.
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CHUANG, Chih-Hsuan, and 莊智軒. "Design and Implementation of Switch Control for Photovoltaic Power Generation Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24412734475749747987.
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碩士國立臺灣科技大學
電機工程系
98
The purpose of this thesis is to improve the efficiency of photovoltaic (PV) systems. A set of a PV system needs an inverter in tradition, and therefore a larger set of a PV system requires relatively more inverters. When a PV system uses more inverters to convert power, energy will be separated to every inverter. If inverters are activated in sequence rather than simultaneously in together, all of the energy can be provided to part of inverters for power conversion. By using this method, the power conversion efficiency will improve. The increase of power conversion efficiency is very high when the energy generated by a PV system is low. This method is used in the thesis. All of the data and simulation are analyzed by MATLAB/Simulink to provide system control algorithm. All of actions and detections are controlled by software and PV system control unit, chip AT89S51. By using this method, it can be modified and read easier and reduced the cost of hardware.
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Lujara, Nelson Kakuru. "Computer aided design of systems for solar powered water pumping by photovoltaics." Thesis, 2012. http://hdl.handle.net/10210/6537.
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D.Ing.Low system efficiency is a critical problem in photovoltaic (PV) applications due to low efficiency of solar cells. Despite this shortcoming, stand-alone PV systems, have proven to be economical and reliable choices in some applications such as telecommunications, vaccine refrigeration and water pumping in remote locations. In this study, CAD algorithms for the design of PV water pumping systems have been developed with the objective of maximizing the conversion efficiency from the solar irradiation to the potential energy of water by taking into account the variations in the pumping head. The study starts by developing loss models of various sub-systems in the photovoltaic dc and ac motor drive water pumping systems. Using MathCad, these models are then used in the simulation of the system. The simulation results are verified experimentally using their equivalent circuit configurations. The efficiency of the array, the pump and the motor are found to be the most critical parameters for the performance of the systems. The efficiencies of other components, such as the inverter, have also been shown to have a significant effect. The study has shown that for operation at the maximum power point, the inclusion of a maximum power tracker is necessary in a dc motor drive system but may be eliminated in PWM inverter-fed induction motor drive systems through proper matching of the system components. The study has further shown that matching of the drive system and the load with the insolation is essential, since maximum system efficiency occurs at a specific head, which varies as the insolation changes. Prior investigation of site insolation variations is therefore a critical requirement.
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"Novel Doherty power amplifier design for advanced communication systems." 2015. http://library.cuhk.edu.hk/record=b6116094.
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随着无线通信的蓬勃发展，新的通信标准不断出现，频谱利用率和数据传输速率提高的同时，传输信号的带宽和均峰比也不断增加。此外，多种通信标准共存的现状要求收发机能够在多个载波频率，高效率地传输不同格式的信号。因此，宽带运行和高效的放大高均峰比信号成为了基站功率放大器设计的基本要求。Doherty 功率放大器结构简单，增加效率的同时能保持中等线性度，故而受到了广泛关注。本文囊括了三个有关增加Doherty 放大器工作带宽、延展高效率区或提高功率利用因子的创新设计。
第一个设计中，复数合路阻抗被用于扩宽Doherty 放大器的高效率区。关于动态阻抗范围，电流比因子和漏极效率的理论分析说明，复数合路阻抗可以当作新的自由度来增加放大器的高效率区。为了验证有关理论，以2GHz 为工作频点，我们使用了相同的基于GaN 工艺的晶体管，分别设计了使用复数合路阻抗和纯实数合路阻抗的Doherty 放大器。连续波测试结果显示，使用复数合路阻抗的Dohety 放大器能够提高9.1dB 的输出回退范围，比基于纯实数合路阻抗的传统设计要高3.6dB。此外，使用单载波、均峰比9.6dB 的WCDMA 信号的测试显示，基于复数合路阻抗的设计在输出功率为33.2dBm 时，其平均漏极效率高达57.4%。
第二个设计中使用了随频率变化的复数合路阻抗，通过控制漏极电流，来同时增加Doherty 放大器的工作带宽和高效率区。为了验证有关理论，我们设计了输出功率42dBm、工作带宽1.8-2.2GHz、输出回退区9dB 的Doherty 放大器。连续波测试结果显示，在8.5dB 回退点处，该设计在8.5dB 回退点和饱和输出点的漏极效率分别高达55-59%和69-73%。使用单载波、均峰比9.6dB 的WCDMA 信号的测试显示，该设计在输出功率为33.5dBm 时，其平均漏极效率高达53-58%，邻道抑制比也能保持在-30dBc。
最后一个设计中，一种在辅助支路加入变换器的Doherty 结构被用于宽带放大。理论分析显示了该结构能够增加功率利用因子，并提供宽带Doherty 特性。为了验证有关理论，我们设计了输出功率20W、工作带宽1.6-2.4GHz、功率利用因子得到改善的Doherty 放大器。连续波测试结果显示，该设计的功率利用因子高达0.94，所有频点均可得到良好的Doherty 效率特性，该设计在6dB回退点和饱和输出点的漏极效率分别高达55-64%和68-76%。在2GHz 处，使用单载波、均峰比6.6dB 的WCDMA 信号的测试显示，该设计在输出功率为37dBm时，其平均漏极效率高达56%，邻道抑制比低于-37dBc。
As modern communication system demands higher spectrum efficiency and data rate, new communication standard using complex modulation scheme has emerged and led to transmitting signal with ever-increasing Peak-to-Average Power Ratio (PAPR). Moreover, the co-existence of different standards requires RF transceivers to support signal transmission at multiple carrier frequencies. Therefore, wideband operation and efficient amplification of high PAPR signal are prime requirements for base-station PA design.
For efficiency enhancement, the Doherty Power Amplifier (DPA) [1] has been regarded as the most popular approach due to its circuit simplicity and moderate linearity. Three innovative DPA design techniques relating to the enhancement of operating bandwidth, high efficiency range and power utilization factor (PUF) are proposed in this work.
In the first demonstration, a novel DPA configuration with Complex Combining Load (CCL) is presented to extend the high efficiency range of the amplifier. Theoretical analysis of dynamic load span, current ratio and drain efficiency reveals that complex combining load can offer a new degree of freedom to boost the Output Back-off (OBO) of DPA. For verification, a 2GHz, equal-cell, GaN HEMT-based DPA is simulated, prototyped and measured with both complex and resistive combining loads. Under Continuous Wave (CW) excitation, measurement results show that the CCL DPA can attain an OBO of 9.1 dB which is 3.6 dB higher than that of the RCL design. In addition, by the use of single-carrier WCDMA signal with PAPR of 9.6 dB and at an average output power of 33.2 dBm, the CCL design is found to deliver an average drain efficiency of 57.4%.
The second design presents a novel technique to extend the bandwidth and efficiency range of DPA by the adoption of frequency-varying Complex Combining Load and proper input current control strategy. For verification, a 42 dBm, 1.8-2.2 GHz DPA with OBO of 8.5 dB was designed, built and characterized. Under CW stimulation, a back-off efficiency (8.5 dB) of 55-59% and saturation efficiency of 69-73% were observed over the entire bandwidth. With single carrier WCDMA signal excitation (PAPR of 9.6 dB), an average drain efficiency of 53-58% was obtained at 33.5 dBm average output power and Adjacent Channel Leakage Power Ratio (ACLR) of around -30 dBc.
In the last technique, a novel DPA configuration with auxiliary transformer is presented for broadband operation. Theoretical analysis reveals that the presented design can offer enhanced PUF and wideband Doherty behavior. Based on the proposed theory, a 1.6-2.4 GHz, 20 W DPA with improved PUF is designed, simulated and measured. Under CW excitation, measurement results indicate that the presented DPA can achieve a PUF of 0.94, good Doherty behavior over the entire frequency band with a 6 dB back-off efficiency of 55-64% and saturated efficiency of 68-76%. In addition, by the use of single-carrier WCDMA signal (centered at 2 GHz) with PAPR of 6.6 dB and at an average output power of 37 dBm, an average drain efficiency of 56% is obtained with ACLR of better than -37 dBc.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Fang, Xiaohu.
Thesis (Ph.D.) Chinese University of Hong Kong, 2015.
Includes bibliographical references.
Abstracts also in Chinese.
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Kertesz, Audrey Catherine. "Modeling and Robust Control Design for Distributed Maximum Power Point Tracking in Photovoltaic Systems." Thesis, 2012. http://hdl.handle.net/1807/33267.
Full textAbstract:
Photovoltaic installations in urban areas operate under uneven lighting conditions. For such a system to achieve its peak efficiency, each solar panel is connected in series through a micro-converter, a dc-dc converter that performs per-panel distributed maximum power point tracking (DMPPT). The objective of this thesis is to design a compensator for the DMPPT micro-converter. A novel, systematic approach to plant modeling is presented for this system, together with a framework for characterizing the plant’s uncertainty. A robust control design procedure based on linear matrix inequalities is then proposed, which ensures robust performance and stability of the time-varying system. The proposed modeling and control design methods are demonstrated for an example rooftop photovoltaic installation. The system and the designed compensator are tested in simulations. Simulation results show satisfactory performance over a range of operating conditions, and the simulated system is shown to track the maximum power point of every panel.
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Hong, Guo-Wei, and 洪國維. "Fuzzy Grey Sliding Mode Control Design for Maximum Power Point Tracking of Photovoltaic Systems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/60650817343797285194.
Full textAbstract:
碩士國立暨南國際大學
電機工程學系
101
The electric power supplied by a photovoltaic power generation system depends on the solar irradiation and temperature. Due to nonlinear I-V characteristics of photovoltaic cells, a maximum power point tracking (MPPT) algorithm is adopted to maximize the output power. The maximum power point can be targeted using any conventional method such as the hill-climbing or incremental conductance method. The drawback is that a fixed small disturbance is used to control the operation voltage. However, the stability and robustness of the mentioned schemes would be difficult to demonstrate. This thesis proposes a fuzzy grey sliding-mode control (FGSMC) strategy for the design of MPPT of photovoltaic systems. A grey-prediction algorithm, based on the grey system theory, is used to establish a grey model to obtain predicted state, and then is introduced into the design of fuzzy logic control. This fuzzy logic control is used to replace the continuous sign function of the reaching law in traditional sliding-mode control, and hence a control input without saturation is obtained in the photovoltaic systems. Based on the Lyapunov stability theory, the design scheme of FGSMC, where the reaching law is formulated by a set of linguistic rules, is successfully proposed to achieve the purpose of the MPPT of photovoltaic systems. The simulation results show that FGSMC can control the nonlinear behavior to achieve the desired maximum power point state very quickly without oscillation, and the switching function is able to avoid saturation. This result implies that the proposed scheme is feasible and effective.
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Chen, Chao-Ting, and 陳昭廷. "Design and Implementation of a Portable Fault Diagnosis Meter for Photovoltaic Power Generation Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/18219513550375800647.
Full textAbstract:
碩士國立勤益科技大學
電機工程系
98
The main purpose of this thesis is to design and implement a portable fault diagnosis meter for a photovoltaic (PV) power generation system. The extension theory and extension neural network(ENN) theory are adopted to diagnose the fault type of a PV power generation system, respectively. A PV power generation system formed with 9 series and 2 parallels Sharp’s PV module NT-R5E3E is constructed by Solar Pro software for simulation. The simulation data is collected at different irradiances and temperatures of a PV power generation system under normal operation and various fault conditions. The gathered data is not only used to construct the classical domains and neighborhood domains of a extension theory, but also to construct the weights of a extension neural network theory. Some simulation results are made to demonstrate the effectiveness of the extension theory and extension neural network theory. The proposed fault diagnosis method of the PV power generation system needs immediate irradiances and temperatures of PV modules and the generation data of PV system, therefore a sensed circuit which can capture the fault characteristic data is designed and implemented. In this thesis, a PIC single chip was adopted to realize a portable photovoltaic power generation system fault diagnosis meter which is established with the extension theory, extension neural network theory and the ZigBee wireless network. Finally, experimental results are also carry out verify the accuracy of the proposed portable fault diagnosis meter for a PV power generation system.
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Mutombo, Ntumba Marc-Alain. "Design and performance analysis of hybrid photovoltaic-thermal grid connected system for residential application." Thesis, 2012. http://hdl.handle.net/10413/10406.
Full textAbstract:
High output electrical energy is obtained from photovoltaic (PV) systems subject to high
irradiance. However, at high irradiance, the efficiency of PV systems drops due to increase of
the temperature of the systems. In order to improve the efficiency of photovoltaic systems, much
effort has been spent on developing hybrid photovoltaic thermal (PVT) systems using water as a
coolant to withdraw heat from solar modules.
This research is focused on the study of the behavior of hybrid PVT collectors using rectangular
channel profiles which provide a large surface for heat exchange between PV panels and thermal
collectors unlike the circular channel profile used in conventional PV systems. In hybrid PVT
systems, coolant water circulates in a closed circuit by means of the thermosyphon phenomenon
and the heat from this water is extracted from a storage tank and can be used in hot water
systems instead of an electric geyser.
Numerical models of water velocity in channels due to the thermosyphon phenomenon and the
temperature of solar modules was developed and a system was designed for modest Durban
household demand. A simulation was run for specific summer and winter days comparing a
conventional PV system and a hybrid PVT system. The results were very encouraging, and
demonstrated that the equipment is capable of extending the PVT application potential in the
domestic sector where more than 40% of electricity cost is heating water.Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012.
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Abhijit, K. "Design And Control of Power Converters for Renewable Energy Systems." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2663.
Full textAbstract:
Renewable energy sources normally require power converters to convert their energy into standardized regulated ac output. The motivation for this thesis is to design and control power converters for renewable energy systems to ensure very good power quality, efficiency and reliability. The renewable energy sources considered are low voltage dc sources such as photovoltaic (PV) modules. Two transformer-isolated power circuit topologies with input voltage of less than 50V are designed and developed for low and medium power applications. Various design and control issues of these converters are identified and new solutions are proposed.
For low power rating of a few hundred watts, a line-frequency transformer interfaced inverter is developed. In the grid connected operation, it is observed that this topology injects considerable lower order odd and even harmonics in the grid current. The reasons for this are identified. A new current control method using adaptive harmonic compensation technique and a proportional-resonant-integral (PRI) controller is proposed. The proposed current controller is designed to ensure that the grid current harmonics are within the limits set by the IEEE 1547-2003 standard.
Phase-locked loops (PLLs) are used for grid synchronization of power converters in grid-tied operation and for closed-loop control reference generation. Analysis and design of synchronous reference frame PLL (SRF-PLL) and second-order generalized integrator (SOGI) based PLLs considering unit vector distortion under the possible non-ideal grid conditions of harmonics, unbalance, dc offsets and frequency deviations are proposed and validated. Both SRF-PLL and SOGI-PLL are low-complexity PLLs. The proposed designs achieve fastest settling time for these PLLs for a given worst-case input condition. The harmonic distortion and dc offsets in the resulting unit vectors are limited to be well within the limits set by the IEEE 1547-2003 standard. The proposed designs can be used to achieve very good performance using conventional low-complexity PLLs without the requirement of advanced PLLs which can be computationally intensive.
A high-frequency (HF) transformer interfaced ac link inverter with a lossless snubber is developed medium power level in the order of few kilowatts. The HF transformer makes the topology compact and economical compared to an equally rated line frequency transformer. A new synchronized modulation method is proposed to suppress the possible over-voltages due to current commutation in the leakage inductance of the HF transformer. The effect of circuit non-ideality of turn-on delay time is analyzed. The proposed modulation mitigates the problem of spurious turn-on that can occur due to the turn-on delay time. The HF inverter, rectifier and snubber devices have soft switching with this modulation. A new reliable start-up method is proposed for this inverter topology without any additional start- up circuitry. This solves the problems of over-voltages and inrush currents during start-up.
The overall research work reported in the thesis shows that it is possible to have compact, reliable and high performance power converters for renewable energy conversion systems. It is also shown that high control performance and power quality can be achieved using the proposed control techniques of low implementation complexity.