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1
Schofield, Daniel M. K. "Power converters for photovoltaic energy generation". Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7029/.
Testo completoAbstract (sommario):
Global demand for renewable energy has provided impetus for increased research into photovoltaic (PV) technology. Photovoltaic modules have intrinsically low efficiency and therefore, to maximise generated electricity, advances must be made in the efficient extraction of energy to maintain viability of their use. In this thesis, efficiency is maximised using novel power electronics. To facilitate advanced design, novel methods for generating accurate models of PV generators are presented. Conventional methods rely on the characterisation of PVs under continuous illumination. These methods cause heating of the module which can degrade the performance below that which would be seen during normal operation. To counter this problem, the use of flashed illumination is presented as a method for unobtrusively generating a PV electrical characteristic which can be used for accurate model-parameter extraction. To develop optimised-switch mode power converters for PVs, the reasons for suboptimal operation in existing converters is analysed and validated experimentally. Whereas existing research has considered the effect of current perturbation at mains frequency, this thesis extends the analysis to 500 kHz, which represents typical switchmode operation. A typical boost converter cannot meet the requirements for optimal power extraction from the PV module and therefore a novel circuit topology based on a SEPIC converter which can achieve optimal conditions is developed and presented. Since the methods for power transfer optimisation presented in this thesis require that the additional hardware is implemented in order to take full advantage of the PV generator, a method is presented whereby the resulting increased cost is significantly reduced. This reduction is achieved through the adaptation of redundant computer power supplies for PV battery charging applications, a method which can be used to produce a PV battery charger with minimal material or design investment.
2
Liu, Guang. "Photovoltaic array simulators". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25103.
Testo completoAbstract (sommario):
Two basic types of photovoltaic (PV) array simulator have been designed and tested. The first involves the use of a pilot panel and variable light source. It is implemented with analogue circuits. A stability analysis based on Popov's method is presented for this simulator with resistance-inductance (R-L) loads. In the second, characteristic array curves are stored in the memory of a microprocessor-based simulator. The design of both simulators is based on the transfer function method. By using the computing facility available, a stability study for the Type I simulator and some dynamic simulations are carried out. Both simulators are capable of driving a special load, namely, an experimental solar pumping system. The experimental results for both types of' simulator are satisfactory in terms of steady state precision and dynamic behaviour when used with this load.
Compared with previously-reported PV array simulator designs [6,7,8,9,18], the two simulators described here have the following distinctive features:
1. A new method of sample curve generation for the Type II simulator results in relatively short sampling period and small memory size.
2. The sample curves of the type II simulator are based directly on the real PV array to be simulated. They are more accurate than the sample curves in references [6,7,9]. 3. Different loads (R, R-L and an experimental solar pumping system) have been considered in the design and have been tested in laboratory.
4. A stability analysis and some dynamic simulations are presented for the type I simulator. An analysis of this type has not been reported in previous studies [6,7,8,9,18].Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
3
van, der Walt Rhyno Lambertus Reyneke. "Photovoltaic based distributed generation power system protection". Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/62807.
Testo completoAbstract (sommario):
In recent years, the world has seen a significant growth in energy requirements. To meet this
requirement and also driven by environmental issues with conventional power plants, engineers
and consumers have started a growing trend in the deployment of distributed renewable power
plants such as photovoltaic (PV) power plants and wind turbines. The introduction of distributed
generation pose some serious issues for power system protection and control engineers. One of
the major challenges are power system protection. Conventional distribution power systems take
on a radial topology, with current flowing from the substation to the loads, yielded unidirectional
power flow. With the addition of distributed generation, power flow and fault current
are becoming bi-directional. This causes loss of coordination between conventional overcurrent
protection devices. Adding power sources downstream of protection devices might also cause
the upstream protection device to be blinded from faults. Conventional overcurrent protection
is mainly based on the fault levels at specific points along the network. By adding renewable
sources, the fault levels increase and become dynamic, based on weather conditions.
In this dissertation, power system faults are modelled with sequence components and simulated
with Digsilent PowerFactory power system software. The modeling of several faults under varying power system parameters are combined with different photovoltaic penetration levels
to establish a framework under which protection challenges can be better defined and
understood. Understanding the effects of distributed generation on three phase power systems
are simplified by modeling power systems with sequence networks. The models for
asymmetrical faults shows the limited affect which distributed generation has on power system
protection. The ability of inverter based distributed generators to provide active control of phase
current, irrespective of unbalanced voltage occurring in the network limits their influence during
asymmetrical faults. Based on this unique ability of inverter based distributed generators (of
which PV energy sources are the main type), solutions are proposed to mitigate or prevent the
occurrence of loss of protection under increasing penetration levels of distributed generation.
The solutions include using zero and negative sequence overcurrent protection, and adapting the
undervoltage disconnection time of distributed generators based on the unique network
parameters where it is used. Repeating the simulations after integrating the proposed solutions
show improved results and better protection coordination under high penetration levels of PV
based distributed generation.Dissertation (MEng)--University of Pretoria, 2017.
Electrical, Electronic and Computer Engineering
MEng
Unrestricted
4
ZHANG, SHAN. "Analytical system for photovoltaic and concentratingsolar power generation". Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-16174.
Testo completoAbstract (sommario):
Energy is the material foundation of human survival and development. Throughout human industrialization process, the fossil energy has made tremendous contributions in the progress of human civilization, economic and social development. For a long time, the development of human energy use patterns makes fossil fuels rapidly depleted and the consequences of environmental deterioration by this pattern lead to the severe challenge for mankind. Many countries start paying more attention to develop the new energy. The solar electricity production system is one of the main new energy power generations. The thesis is a guide of principle for solar power generation system. It focuses on comparisons between photovoltaic and concentrating solar power generations and analysis of their market prospects. The merits and demerits of these two systems will also be pointed out in this thesis.
5
Johnson, Grayden L. "Network connected photovoltaic array". Thesis, Queensland University of Technology, 1994. https://eprints.qut.edu.au/36234/1/36234_Johnson_1994.pdf.
Testo completoAbstract (sommario):
This research project is primarily concerned with the construction, testing and analysis of Australia's first residential roof mounted 1.3 kW photovoltaic array which is connected, via its associated power conditioning equipment, to the utility's electrical distribution network. Also included in this project
was the establishment of computer-based data acquisition systems to be used for monitoring and analysis of essential data. The test facility (SOLAR ONE) was built within The South East Queensland
Electricity Board's (SEQEB) supply area and is situated at Mt Coolum. Work undertaken included a critical review of relevant literature concerned with the interconnection of photovoltaics with the electrical distribution
network, analysis of relevant electrical distribution authority's policy, regulation and guidelines; co-ordinating the building of the test facility,
building the array, installing the associated power conditioning and data acquisition equipment and ongoing monitoring including interpretation of data up to the date of this submission. The results presented demonstrate the applicability of photovoltaics within
the electrical distribution network. Also presented is the analysis of the data gathered from the test facility illustrating the effects of such a system upon the electrical distribution network.
6
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.
Testo completo
7
Kong, Fei. "Development of series connected photovoltaic power inverter". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609938.
Testo completo
8
Thantsha, Nicolas Matome. "Spatially resolved opto-electric measurements of photovoltaic materials and devices". Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/1123.
Testo completoAbstract (sommario):
The objective of this study is to characterize and analyse defects in solar cell devices. Materials used to fabricate solar cells are not defects free and therefore, there is a need to investigate defects in cells. To investigate this, a topographical technique was developed and employed which uses a non-destructive methodology to analyse solar cells. A system was built which uses a technique based on a laser beam induced current (LBIC). LBIC technique involves focusing light on to a surface of a solar cell device in order to create a photo-generated current that can be measured in the external circuit for analyses. The advantage of this technique is that it allows parameter extraction. Parameters that can be extracted include short-circuit current, carrier lifetime and also the external and internal quantum efficiency of a solar cell. In this thesis, LBIC measurements in the form of picture maps are used to indicate the distribution of the localized beam induced current within solar cells. Areas with low minority carrier lifetime in solar cells are made visible by LBIC mapping. Surface reflection intensity measurements of cells can also be mapped using the LBIC system developed in this study. The system is also capable of mapping photo-generated current of a cell below and above room temperature. This thesis also presents an assessment procedure capable of assessing the device and performance parameters with reference to I-V measurements. The dark and illuminated I-V characteristics of solar cells were investigated. The illuminated I-V characteristics of solar cells were obtained using a defocused laser beam. Dark I-V measurements were performed by applying voltage across the cell in the dark and measuring a current through it. The device parameters which describe the behaviour of I-V characteristic were extracted from the I-V data using Particle Swarm Optimization (PSO) method based on a one-and two-diode solar cell models. Solar cells of different technologies were analysed, namely, single-crystalline (c-Si) and multicrystalline (mc-Si) silicon, Edge-defined Film-fed Growth Si (EFG-Si) and Cu(In,Ga)(Se,S)2 (CIGSS) thin film based cells. The LBIC results illustrated the effect of surface reflection features and material defects in the solar cell investigated. IQE at a wavelength of 660 nm were measured on these cells and the results in general emphasised the importance of correcting optical losses, i.e. reflection loss, when characterizing different types of defects. The agreement between the IQE measurements and I-V characteristics of a cell showed that the differences in crystal grains influence the performance of a mc-Si cell. The temperature-dependence of I-V characteristics of a CIGSS solar cell was investigated. The results showed that, for this material, the photo response is reduced at elevated temperatures. In addition to LBIC using a laser beam, solar spectral radiation was employed to obtained device performance parameters. The results emphasised the effect of grain boundaries as a recombination centres for photo-generated hole-pairs. Lastly, mesa diode characterizations of solar cells were investigated. Mesa diodes are achieved by etching down a solar cell so that the plateau regions are formed. Mesa diodes expose the p-n junction, and therefore mesa diode analysis provides a better way of determining and revealing the fundamental current conduction mechanism at the junction. Mesa diodes avoid possible edge effects. This study showed that mesa diodes can be used to characterize spatial non-uniformities in solar cells. The results obtained in this study indicate that LBIC is a useful tool for defect characterization in solar cells. Also LBIC complements other characterization techniques such as I-V characterization.
9
Kroposki, Benjamin David. "A methodology to study photovoltaics and storage system interactions". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03242009-040410/.
Testo completo
10
Jantharamin, Niphat. "Optimal control and management of photovoltaic power generation systems". Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556249.
Testo completo
11
Lin, Chen. "Experimental investigations on performance enhancement of a photovoltaic cooling system". Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691167.
Testo completo
12
Ropp, Michael Eugene. "Design issues for grid-connected photovoltaic systems". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13456.
Testo completo
13
Njouakoua, Tchonko Leon. "Reconfigurable photovoltaic modules for robust nanosatellite power systems". Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2620.
Testo completoAbstract (sommario):
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2018.Until recently, the focus of most solar technology development for space was towards more efficient, more radiation-resistant and increasingly powerful arrays. During a space mission, solar cells are not only exposed to irradiation by electrons, but also to a range of other particles, like protons. Thus, solar cells on robust nanosatellites are extremely exposed to an environment, which includes the high-energy electrons and protons of the earth’s radiation belts, which leads towards the degradation process of the individual solar cell. Solar cell radiation shielding design ensures the protection of the solar cells from the particular radiation environment found in space. While the design principles of a solar photovoltaic automatic switching fault tolerant system which can detect and bypass faulty photovoltaic cells will be presented through this research work. The ability of such a system to be reconfigured using implemented switching matrix system makes it efficient under various environments and faulty conditions.
National Research Foundation (NRF)
14
Pregelj, Aleksandar. "Impact of Distributed Generation on Power Network Operation". Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5127.
Testo completoAbstract (sommario):
Tools and algorithms are proposed that are useful for planning, designing, and operating a distribution network with a significant penetration of distributed generation (DG). In Task 1, a PV system simulation program is developed, which incorporates the most rigorous models for the calculation of insolation, module temperature, and DC and AC power output of a PV system. The effect of random inverter failures is incorporated in the model of a PV system, and a novel performance-derating coefficient is introduced. Furthermore, a novel inverter control algorithm is presented for systems with multiple inverters. The algorithm is designed to increase overall DC/AC conversion efficiency by selectively shutting down some of the inverters during periods of low insolation, thus forcing the remaining inverters to operate at higher efficiency. In Task 2, a procedure is developed to incorporate the uncertainties imposed by stochastic, renewable DG into the conventional tools for analysis of distribution systems. A clustering algorithm is proposed to reduce large input data sets that result from the interaction of stochastic processes that drive DG output with field measurements of feeder load profiles. In addition, a procedure is proposed to determine the boundary points of the original data set, which yield feeder extreme operating conditions. Finally, a Monte Carlo analysis using a reduced data set is presented, to determine the effects of deploying a large number of renewable DG systems on a distribution feeder. In Task 3, the reliability model of an asymmetric, three--phase, non-radial distribution feeder equipped with capacity-constrained DGs is developed and used to quantify the potential reliability improvements due to the intentional islanded operation of parts of the feeder. A procedure for finding optimal positions for DG and protection devices is presented using a custom-tailored adaptive genetic algorithm.
15
Jockell, John F. "A methodology to evaluate photvoltaics : storage as a commercial customer initiated demand side management tool /". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12172008-063414/.
Testo completo
16
Macabebe, Erees Queen Barrido. "Investigation of device and performance parameters of photovoltaic devices". Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1003.
Testo completoAbstract (sommario):
In order to investigate the influence of parasitic resistances, saturation current and diode ideality factor on the performance of photovoltaic devices, parameter extraction routines employing the standard iteration (SI) method and the particle swarm optimization (PSO) method were developed to extract the series resistance, shunt resistance, saturation current and ideality factor from the I-V characteristics of solar cells and PV modules. The well-known one- and two-diode models were used to describe the behavior of the I-V curve and the parameters of the models were determined by approximation and iteration techniques. The SI and the PSO extraction programmes were used to assess the suitability of the one- and the two-diode solar cell models in describing the I-V characteristics of mono- and multicrystalline silicon solar cells, CISS- and CIGSS-based solar cells. This exercise revealed that the two-diode model provides more information regarding the different processes involved in solar cell operation. Between the two methods developed, the PSO method is faster, yielded fitted curves with lower standard deviation of residuals and, therefore, was the preferred extraction method. The PSO method was then used to extract the device parameters of CISS-based solar cells with the CISS layer selenized under different selenization process conditions and CIGSS-based solar cells with varying i-ZnO layer thickness. For the CISS-based solar cells, the detrimental effect of parasitic resistances on device performance increased when the temperature and duration of the selenization process was increased. For the CIGSS-based devices, photogeneration improved with increasing i-ZnO layer thickness. At high forward bias, bulk recombination and/or tunneling-assisted recombination were the dominant processes affecting the I-V characteristics of the devices. v Lastly, device and performance parameters of mono-, multicrystalline silicon and CIS modules derived from I-V characteristics obtained under dark and illuminated conditions were analyzed considering the effects of temperature on the performance of the devices. Results showed that the effects of parasitic resistances are greater under illumination and, under outdoor conditions, the values further declined due to increasing temperature. The saturation current and ideality factor also increased under outdoor conditions which suggest increased recombination and, coupled with the adverse effects of parasitic resistances, these factors result in lower FF and lower maximum power point. Analysis performed on crystalline silicon and thin film devices utilized in this study revealed that parameter extraction from I-V characteristics of photovoltaic devices and, in particular, the implementation of PSO in solar cell device parameter extraction developed in this work is a useful characterization technique.
17
York, Jr John Benson. "An Isolated Micro-Converter for Next-Generation Photovoltaic Infrastructure". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19326.
Testo completoAbstract (sommario):
Photovoltaic (PV) systems are a rapidly growing segment in the renewable energy industry. Though they have humble origins and an uncertain future, the commercial viability of PV has significantly increased, especially in the past decade. In order to make PV useful, however, significant effort has to go into the power conditioning systems that take the low-voltage dc from the panel and create utility compatible ac output. Popular architectures for this process include the centralized inverter and the distributed micro-inverter, each with its own advantages and disadvantages. One attempt to retain the advantages of both architectures is to centralize the inverter function but construct PV panel-level micro-converters which optimize the panel output and condition the power for the inverter. The main focus of this work is to explore the technical challenges that face the evolution of the dc-dc micro-converter and to use them as a template for a vertically integrated design procedure. The individual chapters focus on different levels of the process: topology, modulation and control, transient mitigation, and steady-state optimization. Chapter 2 introduces a new dc-dc topology, the Integrated Boost Resonant (IBR) converter, born out of the natural design requirements for the micro-converter, such as high CEC efficiency, simple structure, and inherent Galvanic isolation. The circuit is a combination of a traditional PWM boost converter and a discontinuous conduction mode (DCM), series resonant circuit. The DCM operation of the high-frequency transformer possesses much lower circulating energy when compared to the traditional CCM behavior. When combined with zero-current-switching (ZCS) for the output diode, it results in a circuit with a high weighted efficiency of 96.8%. Chapter 3 improves upon that topology by adding an optimized modulation scheme to the control strategy. This improves the power stage efficiency at nominal input and enhances the available operating range. The new, hybrid-frequency method utilizes areas where the modulator operates in constant-on, constant-off, and fixed-frequency conditions depending on duty cycle, the resonant period length, and the desired input range. The method extends the operating range as wide as 12-48V and improves the CEC efficiency to 97.2% in the 250-W prototype. Chapter 4 considers the soft-start of the proposed system, which can have a very large capacitive load from the inverter. A new capacitor-transient limited (CTL) soft-start method senses the ac transient across the resonant capacitor, prematurely ending the lower switch on-time in order to prevent an excessive current spike. A prototype design is then applied to the IBR system, allowing safe system startup with a range of capacitive loads from 2μF to 500μF and a consistent peak current without the need for current sensing. Chapter 5 further investigates the impact of voltage ripple on the PV output power. A new method for analyzing the maximum power point tracking (MPPT) efficiency is proposed based on panel-derived models. From the panel model, an expression demonstrating the MPPT efficiency is derived, along with a ripple â "budgetâ " for the harmonic sources. These ripple sources are then analyzed and suggestions for controlling their contributions are proposed that enable circuit designers to make informed and cost-effective design decisions. Chapter 6 illustrates how results from a previous iteration can provide a basis for the next generation\'s design. A zero-voltage-switching (ZVS) version of the circuit in Chapter 2 is proposed, requiring only two additional MOSFETs and one inductor on the low-voltage side. The maximum switching frequency is then increased from 70kHz to 170kHz, allowing for a 46% reduction in converter volume (from 430cm3 to 230cm3) while retaining greater than 97% weighted efficiency.
Ph. D.
18
Bombelli, Paolo. "Harnessing solar energy by bio-photovoltaic devices". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610451.
Testo completo
19
Liu, Guang. "A photovoltaic-powered pumping system". Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30592.
Testo completoAbstract (sommario):
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
20
Vourazelis, Dimitrios G. "Optimization in solar heating/photovoltaic systems". Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA242363.
Testo completoAbstract (sommario):
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 1990.Thesis Advisor(s): Titus, Harold A. Second Reader: Michael, Sherif. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Descriptor(s): Heat Transfer, Theory, Theses, Costs, Heating Elements, Fluid Dynamics, Photovoltaic Effect, Solar Heating, Swimming, Optimization, Installation. DTIC Identifier(s): Swimming Pools, Solar Heating, Photovoltaic Supplies, Filter Pumps, Theses. Author(s) subject terms: Optimization, Solar Heating, Photovoltaics. Includes bibliographical references (p. 57). Also available in print.
21
Alistoun, Warren James. "Investigation of the performance of photovoltaic systems". Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1008396.
Testo completoAbstract (sommario):
The main objective of this study was to investigate the performance of grid integrated PV systems. A data acquisition (DAQ) system was developed to monitor the performance of an existing grid integrated PV system with battery storage. This system is referred to as a grid assisted PV system. A data logger was used together with the inverters built in data logger to monitor environmental and electrical data on a grid tie PV system which was deployed during this study. To investigate the performance of these grid integrated PV systems PV and BOS device characterization was performed. This was achieved by using current voltage curve tracers and the DAQ system developed. Energy yield estimations were calculated referring to the literature review and a meteorological reference for comparison with measured energy yields from the grid tie PV system.
22
Chow, Philip Chi Yung. "Time-resolved optical studies of excited states in organic photovoltaic diodes". Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708343.
Testo completo
23
Gershon, Talia. "Strategies for improving solution-processed ZnO/Cu₂O photovoltaics". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610663.
Testo completo
24
Fink, Jacob Eugene. "Fine Line Metallization of Silicon Heterojunction Solar Cells via Collimated Aerosol Beam Direct Write". Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26656.
Testo completoAbstract (sommario):
Solar energy has come to the forefront as a scalable and largely underutilized renewable energy resource. The current cost of solar electricity, namely from photovoltaics, along with other logistics factors, has prevented the widespread adaptation of the technology. A key determinant of efficiency and cost for a solar cell is the current collector grid. This work presents the Collimated Aerosol Beam Direct Write (CAB-DW) system as a non-contact printing method that can achieve current collector grid finger widths of less than 10 ?m which are amenable to decreasing both resistive and optical losses. The ability to produce high aspect ratio grid fingers, and deposit optimized grid structures on high efficiency SHJ solar cells using silver nanoparticle inks is also demonstrated. A decrease in shadowing and via profile modification of the grid fingers is presented, along with a study of aging and degradation of electrical properties within silver nanoparticle inks.
25
Hau, Wing Yu. "Electrical current converted from optically excited spin current /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202008%20HAU.
Testo completo
26
Chu, Yiu-cheong. "Application of energy saving systems in Hong Kong buildings /". Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25549406.
Testo completo
27
Dzimano, Gwinyai J. "Modeling Of Photovoltaic Systems". The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228307443.
Testo completo
28
Chowdhury, Badrul Hasan. "Irradiance forecasting and dispatching central station photovoltaic power plants". Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/82903.
Testo completoAbstract (sommario):
This dissertation introduces a new operational tool for integrating a photovoltaic (PV) system into the utility's generation mix. It is recognized at the outset, that much of the existing research concentrated on the central PV system and its operations have concluded that technical problems in PV operation will override any value or credit that can be earned by a PV system, and that penetration of a PV plant in the utility will be severely limited. These are real problems and their solutions are sought in this dissertation. Judging from the drawbacks of the static approach, it is felt that a new approach or methodology needs to be developed which would give a central station PV plant its due share of credit. This dissertation deals mainly with the development and implementation of this new approach -- a dynamic rule-based dispatch algorithm which takes into account the problems faced by the dispatch operator during a dispatch interval and channels those into a knowledge base.
The new dynamic dispatch requires forecasts of photovoltaic generations at the beginning of each dispatch interval. A Box-Jenkins time-series method is used to model the sub-hourly solar irradiance. The irradiance data at any specific site is stripped of its periodicities using a pre-whitening process which involves parameterization of certain known atmospheric phenomena. The pre-whitened data series is considered stationary, although some non-stationarity might be introduced by the discontinuities in the data collection during night hours. This model is extended to yield forecast equations which are then used to predict the photovoltaic output expected to occur at certain lead times coinciding with the economic dispatch intervals.
A rule-based (RB) dispatch algorithm is developed in this dissertation. The RB is introduced to operate as a substitute for the dispatch operator. Some of the dispatcher's functions are routine jobs, while some require specialized knowledge or experience. The RB is given these two qualities through a number of rules. This algorithm works in tandem with a conventional economic dispatch algorithm. The functions of the two are coordinated by another algorithm which oversees the now of information and records them.
The RB gives one of 16 possible solutions as and when required. These solutions are written as rules which manipulate the non-committable generation to achieve an optimal solution. The RB system during its operation supervises the fact that the PV generation are kept at the maximum level possible under all constraints. The case study revealed that the thermal generating units which are scheduled by the unit commitment are able to absorb most of the small to medium variations present in the PV generations. In cases of large variations during a single interval, the thermal generators reach their response limits before they can reach their maximum or minimum generation, thus causing mismatches in the load and generation. The mismatches are then picked up by the non-committable sources of generation, comprised of pumped storage units, hydro generation plant, or by interconnection tie-lines. If none of these are sufficient, changes are made in the PV generation schedule.
It is concluded that results depend on the time of the year and the specific utility. The time of the year information is reflected in the load demand profile. Most utilities in the U.S. have single peaks in summer and double peaks in winter. Also, the time of the peak load occurrence varies with season. The utility generating capacity mix influences the results greatly.Ph. D.
29
Pappu, Venkata Ajay Kumar. "Implementing frequency regulation capability in a solar photovoltaic power plant". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2010. http://scholarsmine.mst.edu/thesis/pdf/Pappu_09007dcc807d51ca.pdf.
Testo completoAbstract (sommario):
Thesis (M.S.)--Missouri University of Science and Technology, 2010.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed July 19, 2010) Includes bibliographical references (p. 88-90).
30
Smith, Steven. "SIZE OPTIMIZATION OF PHOTOVOLTAIC ARRAYS AND ENERGY STORAGE IN A DISTRIBUTION FEEDER". OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2309.
Testo completoAbstract (sommario):
As utilities become more interested in using renewable energy to power the grid, the problem becomes how to size and locate the generation facilities. This thesis approaches the idea of using distributed medium scale generation facilities at the distribution feeder level. We propose an algorithm to determine the optimum size of a photovoltaic(PV) array and an energy storage system for a distribution feeder. The cost of operating a feeder is quantified by considering the net load at the substation, voltage changes, load following, and the initial cost of implementing a photovoltaic system and a battery energy storage system. The PV inverter is utilized in order to improve the voltage on the circuit and is sized proportionally to the array size. The energy storage system operates in peak shaving and load following capacities in order to reduce stress on current generation facilities. The algorithm then operates to minimize the total cost of the feeder operation for a year by sizing these distributed generation resources utilizing particle swarm optimization. Optimization of a real-world system yielding results where the power at the substation (including all losses) is reduced by 5.39% over the course of a year and the average voltage drop on the circuit is improved by 50.17% using the proposed photovoltaic inverter control scheme.
31
Kheder, Abdul-Sameei Yaseen. "Starting high inertia, high friction loads from limited power sources". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184455.
Testo completoAbstract (sommario):
At starting, electrical motors require large power and current. This may not be a problem in a large electrical system but it may be very severe for a limited power source like a solar array. If a direct approach is taken the array rating must be 5-6 times the motor rating in order to start the motor and its high inertia high friction load. Batteries have been used to store energy and supply that energy for starting. Batteries need maintenance and their low efficiency is a problem too. In this study a new type of controller has been suggested and developed for the use with D.C. motors. Computer simulation showed promising results. The controller uses the array power, which is equal to the rated power of the motor, for starting and for running condition. Experimental results showed that the theoretical results are applicable.
32
LaBella, Thomas Matthew. "A High-Efficiency Hybrid Resonant Microconverter for Photovoltaic Generation Systems". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/50526.
Testo completoAbstract (sommario):
The demand for increased renewable energy production has led to increased
photovoltaic (PV) installations worldwide. As this demand continues to grow, it is
important that the costs of PV installations decrease while the power output capability
increases. One of the components in PV installations that has lots of room for improvement
is the power conditioning system. The power conditioning system is responsible for
converting the power output of PV modules into power useable by the utility grid while
insuring the PV array is outputting the maximum available power. Modular power
conditioning systems, where each PV module has its own power converter, have been
proven to yield higher output power due to their superior maximum power point tracking
capabilities. However, this comes with the disadvantages of higher costs and lower power
conversion efficiencies due to the increased number of power electronics converters. The
primary objective of this dissertation is to develop a high-efficiency, low cost
microconverter in an effort to increase the output power capability and decrease the cost of
modular power conditioning systems.
First, existing isolated dc-dc converter topologies are explored and a new topology
is proposed based on the highly-efficient series resonant converter operating near the series
resonant frequency. Two different hybrid modes of operation are introduced in order to
add wide input-voltage regulation capability to the series resonant converter while
achieving high efficiency through low circulating currents, zero-current switching (ZCS)
of the output diodes, zero-voltage switching (ZVS) and/or ZCS of the primary side active
switches, and direct power transfer from the source to the load for the majority of the
switching cycle. Each operating mode is analyzed in detail using state-plane trajectory
plots. A systematic design approach that is unique to the newly proposed converter is
presented along with a detailed loss analysis and loss model. A 300-W microconverter
prototype is designed to experimentally validate the analysis and loss model. The converter
featured a 97.7% weighted California Energy Commission (CEC) efficiency with a
nominal input voltage of 30 V. This is higher than any other reported CEC efficiency for
PV microconverters in literature to date.
Each operating mode of the proposed converter can be controlled using simple
fixed-frequency pulse-width modulation (PWM) based techniques, which makes
implementation of control straightforward. Simplified models of each operating mode are
derived as well as control-to-input voltage transfer functions. A smooth transition method
is then introduced using a two-carrier PWM modulator, which allows the converter to
transition between operating modes quickly and smoothly. The performance of the voltage
controllers and transition method were verified experimentally.
To ensure the proposed converter is compatible with different types of modular
power conditioning system architectures, system-level interaction issues associated with
different modular applications are explored. The first issue is soft start, which is necessary
when the converter is beginning operation with a large capacitive load. A novel soft start
method is introduced that allows the converter to start up safely and quickly, even with a
short-circuited output. Maximum power point tracking and double line frequency ripple
rejection are also explored, both of which are very important to ensuring the PV module is
outputting the maximum amount of available power.
Lastly, this work deals with efficiency optimization of the proposed converter. It
is possible to use magnetic integration so that the resonant inductor can be incorporated
into the isolation transformer by way of the transformer leakage inductance in order to
reduce parts count and associated costs. This chapter, however, analyzes the disadvantages
to this technique, which are increased proximity effect losses resulting in higher conduction
losses. A new prototype is designed and tested that utilizes an external resonant inductor
and the CEC efficiency was increased from 97.7% to 98.0% with a marginal 1.8% total
cost increase. Additionally, a variable frequency efficiency optimization algorithm is
proposed which increases the system efficiency under the high-line and low-line input
voltage conditions. This algorithm is used for efficiency optimization only and not control,
so the previously presented simple fixed-frequency modeling and control techniques can
still be utilized.Ph. D.
33
Tam, Wing-yan. "Functional diblock copolymers for nanofabrications and photovoltaic applications". Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43907301.
Testo completo
34
MacGregor, Paul R. "US photovoltaic industry competiveness : a market penetration analysis". Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/28765.
Testo completo
35
Tam, Wing-yan, e 譚詠欣. "Functional diblock copolymers for nanofabrications and photovoltaic applications". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43907301.
Testo completo
36
Mulherin, Rhiannon Clare. "Fully conjugated diblock copolymers for photovoltaic devices". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610724.
Testo completo
37
Foreman, Mark McKinney. "Control and operation of SMES and SMES/PV systems". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10062009-020156/.
Testo completo
38
Bawakyillenuo, Simon. "Rural electrification in Ghana : issues of photovoltaic energy technology utilisation". Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:579.
Testo completoAbstract (sommario):
Energy plays a pivotal role in human development. Not only is it sine qua non for national economic development, but it also provides services that enhance social development including, health and sanitation, education, potable water, cooking. In spite of this, at present, there are about two billion people without access to modern sources of energy, most of them in the rural areas of the developing world. Consequentially, the social and economic development of these two billion people hangs in the balance. In recent times, however, considerable advocacy has taken place in the academic and policy studies, environmental fora, and national agenda about solar PV energy technology serving as a panacea to the energy problems of rural populations in developing countries, especially Sub-Sahara Africa, whilst also helping to reduce greenhouse gas emissions. Notwithstanding this great advocacy, the literature on the dissemination of this technology has been incomplete in fostering understanding on the discourses surrounding its low dissemination rates in rural Ghana compared to countries such as Kenya and Zimbabwe; the sustainability of installed solar PV systems; and the usefulness of solar PV in serving the needs of the rural poor. In resorting to an interdisciplinary approach (methodology and theoretical foundation), this study has explored the energy perspectives of Ghana, the dynamics of rural electrification and energy needs, and the interplay of processes and forces underpinning the adoption and non-adoption of solar PV in rural Ghana. Results of this study show that, Ghana has abundant renewable energy resources, especially solar radiation. However, the study further reveals that the resource base alone of solar PV technology is not the panacea to its successful dissemination and the energy needs of all in rural Ghana. Significantly, this study has shown that the adoption and non-adoption perspectives of solar PV in rural Ghana and the sustainability of installed solar PV systems, as well as the disparate levels of solar PV dissemination in Ghana, Kenya and Zimbabwe, are contingent on multi-dimensional circumstances. This stands in contrast to the majority of literature that often emphasise cost as the sole determining factor of the non-adoption of solar PV in most developing countries. Results of this study therefore have implications for rural energy supply policy approaches and other institutional arrangements on solar PV issues in Ghana.
39
Bhandari, Yashpal. "Star-shaped molecules for organic photovoltaics synthesis and structure-property relationships /". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 188 p, 2007. http://proquest.umi.com/pqdweb?did=1313923651&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Testo completo
40
Sana, Peyman. "Design, fabrication and analysis of high efficiency multicrystalline silicon solar cells". Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/15039.
Testo completo
41
Leung, Qing-yun, e 梁青雲. "Synthesis, characterization and photovoltaic applications of fused heterocyclic molecules with intramolecular charge transfer properties". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44527755.
Testo completo
42
Shaheen, Momtaz. "Analytical model of an n+-p-p+ concentrator solar cell". Virtual Press, 1988. http://liblink.bsu.edu/uhtbin/catkey/539622.
Testo completoAbstract (sommario):
Concentrator solar cells operate under the conditions of non-uniform illumination and varying spectral content of incident sunlight. To predict the performance of such cells, an analytical model must account for varying carrier photogeneration rates within the cell. Further, the back surface junction fabricated to reduce recombination at the back contact must be included in the analysis.Most models of n+-p-p+ cells assume uniform generation rates within individual layers. In this study, a one-dimensional n+-p-p+ concentrator solar cell is modeled for all levels of illumination of incident sunlight. The photocarrier generation rate is considered as non-uniform in each layer of the cell. An absorption model is incorporated to permit the application for various spectral mixes of incident sunlight. The model also includes the effects of finite surface recombination velocities at the surfaces. Carrier transport equations for the three layers of the cell are developed and solved for the excess carrier concentrations under the assumptions of the model. Junction current density-voltage relationships for the two junctions of the cell are derived. The use of the current density equations in the evaluation of cell performance is discussed.Department of Physics and Astronomy
43
Wang, Xiaoting. "Very High Efficiency Solar Cell (VHESC) sub-module measurement". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 55 p, 2008. http://proquest.umi.com/pqdweb?did=1654493881&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Testo completo
44
Golder, Andrew S. Miu Karen Nan. "Photovoltaic generator modeling for large scale distribution system studies /". Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1220.
Testo completo
45
Khallat, Mohamed Ali. "A methodology for evaluating photovoltaic-fuel hybird energy systems". Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/53626.
Testo completoAbstract (sommario):
A major issue encountered in the large scale use of Photovoltaic (PV) energy sources for the production of electricity is the variability of the resource itself. Extensive fluctuations of the PV generation may cause dynamic operational problems for an electric utility. In order to remedy this situation it is proposed that fuel cell power plants be operated in parallel with PV arrays. This hybrid operation will help to smooth out the fluctuating PV output. Because of its high ramping capability the fuel cell will be able to absorb such fluctuations.
An overall methodology is presented to evaluate the PV system in a large utility. This methodology has two parts-planning and operation. The aim of the planning study is to determine the capacity credit of a PV system based on the loss of load probability (LOLP). Long term SOLMET data is used to determine the nature of available insolation at a particular site. The expected value of hourly insolation is used in the planning study. The aim of the operation study is to validate the results of planning study in the shorter operational time frame, and determine the fuel cell requirements and associated operating cost savings for each penetration level of PV.
A technique to find the maximum penetration level of PV, without causing any economic penalty, is presented. It is found that the penetration level can be increased up to 15.62% of peak load by adding fuel cells to the system under consideration. The annual peak load for this system is taken as 6400 MW. It must be mentioned here that, similar evaluations for other systems may yield somewhat different results. This technique is general enough such that it can be used for other intermittent sources of generation as well.Ph. D.
46
Coulibaly, Ibrahim. "Microcomputer based optimization model for photovoltaic system performance analysis". Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/104314.
Testo completo
47
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.
Testo completoAbstract (sommario):
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.
48
Ringel, S. A. "Growth and process induced defects and recombination mechanisms in AIGaAs/GaAs and CdZnx Te/CdS photovoltaic device structures". Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/13330.
Testo completo
49
Zhang, Weifeng. "Novel thiophene-based molecular materials with enhanced functional properties for photovoltaic applications". HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1215.
Testo completo
50
Liu, Yan-Dun, e 劉炎敦. "Smart Photovoltaic Power Generation System Design". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/37c883.
Testo completoAbstract (sommario):
碩士國立中正大學
通訊工程研究所
102
Due to limited storage of electricity, the demand-response problem occurs often during the summer time in Taiwan. As a feasible solution, the design of smart grid has recently become the focus of most countries, including Taiwan. This Thesis proposes a simple and low cost design for the control and monitoring of solar power generation and storage. In this work, we first measure the open circuit voltage (Voc) and short circuit current (Isc) of solar cells using a multimeter. Then, we explore and analyze how the power generation time and the sunshine exposure time affect the output power of solar cells. For implementation, we used the LabVIEW software tool to design a small photovoltaic power generation and monitoring system. We selected the solar cells as generation device and lead acid battery as storage equipment. Our system can estimate the percentage of electricity stored and monitor the solar cells in real time using related sensors. With this system, users can switch to using more electricity from the solar energy system when there is more illumination; on the contrary, users can switch to using less electricity from the solar energy system, when there is less illumination. In our experiments, the battery State-of-Charge (SOC) and the TaiPower’s peak power supply time period were parameterized. Three power loads with different power requirements (low, medium, and high) were used for experiments such that different scenarios of power usage can be emulated. Compared to a conventional solar power system that only uses SOC for controlling storage charging/discharging, we validated that our system can provide more green power during the pre-assigned peak hours. As a result, our system also reduces the TaiPower’s peak workload. Keywords: Photovoltaic power generation system, green energy, LabVIEW, stroage system, smart grid