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ACTIVE OPTIMAL CONTROL STRATEGIES FOR INCREASING THE EFFICIENCY OF PHOTOVOLTAIC CELLSAljoaba, Sharif 01 January 2013 (has links)
Energy consumption has increased drastically during the last century. Currently, the worldwide energy consumption is about 17.4 TW and is predicted to reach 25 TW by 2035. Solar energy has emerged as one of the potential renewable energy sources. Since its first physical recognition in 1887 by Adams and Day till nowadays, research in solar energy is continuously developing. This has lead to many achievements and milestones that introduced it as one of the most reliable and sustainable energy sources. Recently, the International Energy Agency declared that solar energy is predicted to be one of the major electricity production energy sources by 2035.
Enhancing the efficiency and lifecycle of photovoltaic (PV) modules leads to significant cost reduction. Reducing the temperature of the PV module improves its efficiency and enhances its lifecycle. To better understand the PV module performance, it is important to study the interaction between the output power and the temperature. A model that is capable of predicting the PV module temperature and its effects on the output power considering the individual contribution of the solar spectrum wavelengths significantly advances the PV module designs toward higher efficiency.
In this work, a thermoelectrical model is developed to predict the effects of the solar spectrum wavelengths on the PV module performance. The model is characterized and validated under real meteorological conditions where experimental temperature and output power of the PV module measurements are shown to agree with the predicted results.
The model is used to validate the concept of active optical filtering. Since this model is wavelength-based, it is used to design an active optical filter for PV applications. Applying this filter to the PV module is expected to increase the output power of the module by filtering the spectrum wavelengths. The active filter performance is optimized, where different cutoff wavelengths are used to maximize the module output power. It is predicted that if the optimized active optical filter is applied to the PV module, the module efficiency is predicted to increase by about 1%. Different technologies are considered for physical implementation of the active optical filter.
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Copper Indium Diselenide Nanowire Arrays in Alumina Membranes Deposited on Molybdenum and Other Back Contact SubstratesNadimpally, Bhavananda R 01 January 2013 (has links)
Heterojunctions of CuInSe2 (CIS) nanowires with cadmium sulfide (CdS) were fabricated demonstrating for the first time, vertically aligned nanowires of CIS in the conventional Mo/CIS/CdS stack. These devices were studied for their material and electrical characteristics to provide a better understanding of the transport phenomena governing the operation of heterojunctions involving CIS nanowires. Removal of several key bottlenecks was crucial in achieving this. For example, it was found that to fabricate alumina membranes on molybdenum substrates, a thin interlayer of tungsten had to be inserted. A qualitative model was proposed to explain the difficulty in fabricating anodized aluminum oxide (AAO) membranes directly on Mo. Experimental results were used to corroborate this model.
Subsequently, a general procedure to use any material that can be deposited using sputtering or evaporation as a back contact for nanowires grown using AAO templates was developed. Experimental work to demonstrate this by transferring thin AAO templates onto flexible Polyimide (PI) substrates was performed. This pattern transfer approach opens doors for a wide variety of applications on almost any substrate. Any material that can be deposited by physical means can then be used as a back contact.
Electron-beam induced deposition using a liquid precursor (LP-EBID) was used to selectively grow preconceived patterns of compound semiconductor (CdS) nanoparticles. Stoichiometric CdS nanoparticle patterns were grown successfully using this method. They were structurally and optically characterized indicating high purity deposits. This approach is promising because it marries the precision of e-beam lithography with the versatility of solution based deposition methods.
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The impact of national oil companies on the energy security of OECD countriesMunro, Hugh M. January 2012 (has links)
National oil companies (NOCs) control over 80 percent of world oil reserves and over 50 percent of gas reserves and hold exclusive rights to exploration and development of oil and gas reserves within their home countries. Because of host government involvement and supervision, NOCs may also act as instruments of state, implementing government foreign and domestic policies such as wealth re-distribution through the provision of subsidised oil products, job creation, and economic development. Such activities can lead to restricted availability of funds for finding and developing reserves for future production and to inefficiencies in current production and distribution. This thesis assesses the geopolitical factors that influence the conduct, strategies and priorities of NOCs and how these may impact on the continuing security of energy supplies to countries which are members of the Organisation for Economic Co-operation and Development (OECD). It will focus on ten NOCs supplying oil to world markets and two which supply gas to the European market. The study will also review the activities and .scope for influence as state instruments of Sovereign Wealth Funds which have been established by states with NOCs, in particular, those which have earned substantial petro-dollar surpluses, during the period of high oil and gas prices of2006-2008. In an age of global interdependence between nations, specific objectives of this thesis are to consider the implications of anticipated growth in world demand for oil and gas supplies over the next 20 years, whether world production capacity is likely to grow to meet increases in world demand, the potential impact on world oil and gas supplies of the policies and practices of NOCs, in particular, the desire of host governments to require NOCs to follow non- commercial objectives, and the responses from OECD countries to threats to their energy security from potential restrictions on supplies.
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Determination of Single Pole Breaker Reclose Time and System Performance Using Real Time SimulationGodavarthi, Venkata Sridivya 19 May 2017 (has links)
This thesis investigates single pole reclosing in series capacitor compensated line. An algorithm is developed to determine the optimal dead time required for single pole reclose of circuit breakers and to reduce the randomness of reclosing time. The algorithm considers conditions of system, fault, voltage zero crossing, arc, and IEEE C37.104-2012 standard de-ionization time. This study also addresses difficulties of single pole reclose operation such as over-voltages at the line, secondary arc extinguishing time, dead time, over-voltages across the series capacitor, and negative sequence current. The system performance is evaluated using a set of metrics based on those operation difficulties. Methods used in the industry such as shunt reactor with the neutral reactor, surge arrester, and MOV are modelled and simulated to capture their effect on the operation difficulties. Comparative analysis is made to rank the effectiveness of each element against difficulties in operating single pole reclosing of circuit breakers.
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Event Detection Using Correlation within Arrays of Streaming PMU DataLandford, Jordan 26 May 2016 (has links)
This thesis provides a synchrophasor data analysis methodology that leverages both statistical correlation techniques and a statistical distribution in order to identify data inconsistencies, as well as power system contingencies. This research utilizes archived Phasor Measurement Unit (PMU) data obtained from the Bonneville Power Administration in order to show that this methodology is not only feasible, but extremely useful for power systems monitoring, decision support, and planning purposes.
By analyzing positive sequence voltage angles between a pair of PMUs at two different substation locations, an historic record of correlation is established. From this record, a Rayleigh distribution of correlation coefficients is calculated. The statistical parameters of this Rayleigh distribution are used to infer occurrences of power system and data events.
To monitor an entire system, a simple solution would be observing each of these parameters for every PMU combination. One issue with this approach is that correlation of some PMU pairs may be redundant or yield little value to monitoring capabilities. Additionally, this approach quickly encounters scalability issues as each additional PMU adds considerably to computation - for example, if the system contains n PMUs the amount of computations will be n(n-1)/2. System-wide monitoring of these parameters in this fashion is cumbersome and inefficient.
To address these issues, an alternative scheme is proposed which involves monitoring only a subset of PMUs characterized by electrically coupled zones, or clusters, of PMUs. These clusters include both electrically-distant and electrically-near PMU sites. When monitored over an event, these yield statistical parameters sufficient for detecting event occurrences. This clustering scheme can be utilized to significantly decrease computation time and allocation of resources while maintaining optimal system observability.
Results from the statistical methods are presented for a select few case studies for both data and power system event detection. In addition, determination of cluster size and content is discussed in detail. Lastly, the viability of monitoring pertinent statistical parameters over various clustering schemes is demonstrated.
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Exploring Relationships Between Building And Transportation Energy Use Of Residents In U.S. Metropolitan RegionsPede, Timothy 01 January 2014 (has links)
There is much potential to decrease energy consumption in the U.S. by encouraging compact, centralized development. Although many studies have examined the extent to which built environment and demographic factors are related to household energy use, few have considered both building and transportation energy together. We hypothesized that residents living further from city centers, or urban cores, consume more energy for both purposes than their inner city counterparts, resulting in a direct relationship between building and transportation energy usage. This hypothesis was tested with two case studies.
The first focused on New York City. Annual building energy per unit of parcels, or tax lots, containing large multi-family structures was compared to the daily transportation energy use per household of traffic analysis zones (TAZs) (estimated with a regional travel demand model). Transportation energy showed a strong spatial pattern, with distance to urban core explaining 63% of variation in consumption. Building energy use was randomly distributed, resulting in a weak negative correlation with transportation energy. However, both correlation with distance to urban core and transportation energy became significant and positive when portion of detached single-family units for TAZs was used as a proxy for building energy. Structural equation models (SEMs) revealed a direct relationship between log lot depth and both uses of energy, and inverse relationship between portion of attached housing units and transportation energy. This supports the notion that sprawling development increases both the building and transportation energy consumption of households.
For the second analysis, annual building and automobile energy use per household were estimated for block groups across the 50 most populous U.S. metropolitan regions with Esri Consumer Expenditure Data. Both forms of energy consumption per household were lowest in inner cities and increased at greater distances from urban cores. Although there may be some error in estimates from modeled expenditure data, characteristics associated with lower energy use, such as portion of attached housing units and commuters that utilize transit or pedestrian modes, were negatively correlated with distance to urban core.
Overall, this work suggests there are spatial patterns to household energy consumption, with households further from urban cores using more building and transportation energy. There is the greatest gain in efficiency to be had by suburban residents.
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Identification of Power System Stability Using Relevant ModesWhitlock, Rogers, Jr 17 December 2011 (has links)
The purpose of this investigation is to identify appropriate location of capacitor banks and sources of reactive power by studying power system stability in the vicinity of system equilibrium states. The locations for reactive power sources are determined by identifying those modes of the system that participate most in the system behavior in general and in dictating the final state of the system after experiencing faults or disturbances. To identify the relevant modes of the system that participate most in the system dynamic, we shall make use of modal and participation analysis for different system conditions. We also apply modal and participation analysis to a system in order to identify the components of greatest impact that result in the most efficient system control. The ideas developed in this study are used to analyze and identify weak boundaries of the IEEE 39- Bus system that contribute to the system’s instability.
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Steady State Voltage Stability Enhancement Using Shunt and Series FACTS DevicesLakkireddy, Jahnavi 13 August 2014 (has links)
It is specifically important to focus on voltage stability analysis of the power system to avoid worst case scenarios such as voltage collapse. The purpose of this thesis is to identify methods for enhancing the steady-state voltage stability using FACTS devices and determining their impact on real and reactive power losses, improvement of bus voltage magnitude, and transmission line loadability. To achieve this, FACTS devices such as Static VAR Compensator (SVC), Static Synchronous Compensator (STATCOM), and Thyristor Controlled Series Capacitor (TCSC) are used in the test system as three separate test cases. The results obtained assist in drawing conclusions on the effectiveness of each FACTS devices at generator, load and swing buses, on lines between two load buses, and between a load bus and a generator bus, in terms of metrics such as voltage magnitude profile, PV curves, and active and reactive power losses.
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Adaptive Online Transient Stability Assessment of Power Systems for Operational PurposesAl Marhoon, Hussain Hassan 11 August 2015 (has links)
Online stability assessment is an important problem that has not been solved completely yet. The purpose of this research is to tackle online transient stability assessment. Currently, most utility companies use step-by-step integration in order to set protective equipment so that they effectively work for critical contingencies. However, there are times an unforeseen contingency may occur which may cause the system to transit and the protective equipment to misoperate and does not isolate the disturbed part of the system. This research introduces a method that automatically determines a group of generators that participate in system separation and hence transient instability. The method consists of four phases: modeling and simulation, critical machines identification, online transient stability assessment, and critical clearing time calculation. In the modeling and simulation phase, the power system is built and the generators’ rotor angles and speeds are captured. In the critical machines identification phase, the average instantaneous rotor accelerating powers, coherency measures, the during-fault rotor angles and speeds characteristics, and the pre- and post-fault rotor angles are used to identify the Severely Disturbed Group (SDG) of machines. The results of this phase are used to calculate the kinetic energy of the SDG and potential energy of another (or possibly the same) group of generators. Utilization and success of the proposed method will be documented using results from the IEEE 39-Bus test system. Each step of each phase will be demonstrated as needed. The proposed method is compared to step-by-step integration and two direct methods. The suitability of the proposed method for operation will be shown in cases where the Y-Bus matrix and rotor angles and speeds are given. The proof of concept of the proposed method was used in simulating the test system and encouraging results of the simulation were published in [1] and [2]. The proof of concept is the foundation of the method proposed in this dissertation to determine transient stability of large-scale power systems.
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Utilization of Distributed Generation in Power System Peak Hour Load Shedding ReductionBalachandran, Nandu 13 May 2016 (has links)
An approach to utilize Distributed Generation (DG) to minimize the total load shedding by analyzing the power system in Transactive energy framework is proposed. An algorithm to optimize power system in forward and spot markets to maximize an electric utility’s profit by optimizing purchase of power from DG is developed. The proposed algorithm is a multi-objective optimization with the main objective to maximize a utility’s profit by minimizing overall cost of production, load shedding, and purchase of power from distributed generators. This work also proposes a method to price power in forward and spot markets using existing LMP techniques. Transactive accounting has been performed to quantify the consumer payments in both markets. The algorithm is tested in two test systems; a 6-bus system and modified IEEE 14-bus system. The results show that by investing in DG, utility benefits from profit increase, load shedding reduction, and transmission line loading improvement.
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