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ASU Electronic Theses and Dissertations


Contributor
Date Range
2010 2017

This thesis provides a cost to benefit analysis of the proposed next generation of distribution systems- the Future Renewable Electric Energy Distribution Management (FREEDM) system. With the increasing penetration of renewable energy sources onto the grid, it becomes necessary to have an infrastructure that allows for easy integration of these resources coupled with features like enhanced reliability of the system and fast pro-tection from faults. The Solid State Transformer (SST) and the Fault Isolation Device (FID) make for the core of the FREEDM system and have huge investment costs. Some key features of the FREEDM system include improved power flow ...

Contributors
Raman, Apurva, Heydt, Gerald, Karady, George, et al.
Created Date
2015

The development of a Solid State Transformer (SST) that incorporates a DC-DC multiport converter to integrate both photovoltaic (PV) power generation and battery energy storage is presented in this dissertation. The DC-DC stage is based on a quad-active-bridge (QAB) converter which not only provides isolation for the load, but also for the PV and storage. The AC-DC stage is implemented with a pulse-width-modulated (PWM) single phase rectifier. A unified gyrator-based average model is developed for a general multi-active-bridge (MAB) converter controlled through phase-shift modulation (PSM). Expressions to determine the power rating of the MAB ports are also derived. The developed ...

Contributors
Falcones, Sixifo Daniel, Ayyanar, Raja, Karady, George, et al.
Created Date
2011

A new photovoltaic (PV) array power converter circuit is presented. The salient features of this inverter are: transformerless topology, grounded PV array, and only film capacitors. The motivations are to reduce cost, eliminate leakage ground currents, and improve reliability. The use of Silicon Carbide (SiC) transistors is the key enabling technology for this particular circuit to attain good efficiency. Traditionally, grid connected PV inverters required a transformer for isolation and safety. The disadvantage of high frequency transformer based inverters is complexity and cost. Transformerless inverters have become more popular recently, although they can be challenging to implement because of possible ...

Contributors
Breazeale, Lloyd Caleb, Ayyanar, Raja, Karady, George, et al.
Created Date
2014

This dissertation presents a new hybrid fault current limiter (FCL) topology that is primarily intended to protect single-phase power equipment. It can however be extended to protect three phase systems but would need three devices to protect each individual phase. In comparison against the existing fault current limiter technology, the salient fea-tures of the proposed topology are: a) provides variable impedance that provides a 50% reduction in prospective fault current; b) near instantaneous response time which is with-in the first half cycle (1-4 ms); c) the use of semiconductor switches as the commutating switch which produces reduced leakage current, reduced ...

Contributors
Prigmore, Jay, Karady, George G, Ayyanar, Raja, et al.
Created Date
2013

A novel integrated constant current LED driver design on a single chip is developed in this dissertation. The entire design consists of two sections. The first section is a DC-DC switching regulator (boost regulator) as the frontend power supply; the second section is the constant current LED driver system. In the first section, a pulse width modulated (PWM) peak current mode boost regulator is utilized. The overall boost regulator system and its related sub-cells are explained. Among them, an original error amplifier design, a current sensing circuit and slope compensation circuit are presented. In the second section – the focus ...

Contributors
Wang, Ge, Holbert, Keith E, Song, Hongjiang, et al.
Created Date
2016

All-dielectric self-supporting (ADSS) fiber optic cables are used for data transfer by the utilities. They are installed along high voltage transmission lines. Dry band arcing, a phenomenon which is observed in outdoor insulators, is also observed in ADSS cables. The heat developed during dry band arcing damages the ADSS cables' outer sheath. A method is presented here to rate the cable sheath using the power developed during dry band arcing. Because of the small diameter of ADSS cables, mechanical vibration is induced in ADSS cable. In order to avoid damage, vibration dampers known as spiral vibration dampers (SVD) are used ...

Contributors
Prabakar, Kumaraguru, Karady, George G, Vittal, Vijay, et al.
Created Date
2011

This thesis is focused on the study of wind energy integration and is divided into two segments. The first part of the thesis deals with developing a reliability evaluation technique for a wind integrated power system. A multiple-partial outage model is utilized to accurately calculate the wind generation availability. A methodology is presented to estimate the outage probability of wind generators while incorporating their reduced power output levels at low wind speeds. Subsequently, power system reliability is assessed by calculating the loss of load probability (LOLP) and the effect of wind integration on the overall system is analyzed. Actual generation ...

Contributors
Sinha, Anubhav, Heydt, Gerald T, Vittal, Vijay, et al.
Created Date
2012

This thesis provides a cost to benefit assessment of the proposed next generation distribution system, the Future Renewable Electric Energy Distribution Management (FREEDM) system. In this thesis, a probabilistic study is conducted to determine the payback period for an investment made in the FREEDM distribution system. The stochastic study will help in performing a detailed analysis in estimating the probability density function and statistics associated with the payback period. This thesis also identifies several parameters associated with the FREEDM system, which are used in the cost benefit study to evaluate the investment and several direct and indirect benefits. Different topologies ...

Contributors
Dinakar, Abhishek, Heydt, Gerald T, Vittal, Vijay, et al.
Created Date
2016

This dissertation presents a novel current source converter topology that is primarily intended for single-phase photovoltaic (PV) applications. In comparison with the existing PV inverter technology, the salient features of the proposed topology are: a) the low frequency (double of line frequency) ripple that is common to single-phase inverters is greatly reduced; b) the absence of low frequency ripple enables significantly reduced size pass components to achieve necessary DC-link stiffness and c) improved maximum power point tracking (MPPT) performance is readily achieved due to the tightened current ripple even with reduced-size passive components. The proposed topology does not utilize any ...

Contributors
Bush, Craig R., Ayyanar, Raja, Karam, Lina, et al.
Created Date
2013

The subject of this thesis is distribution level load management using a pricing signal in a smart grid infrastructure. The project relates to energy management in a spe-cialized distribution system known as the Future Renewable Electric Energy Delivery and Management (FREEDM) system. Energy management through demand response is one of the key applications of smart grid. Demand response today is envisioned as a method in which the price could be communicated to the consumers and they may shift their loads from high price periods to the low price periods. The development and deployment of the FREEDM system necessitates controls of ...

Contributors
Musani, Aatif, Heydt, Gerald, Ayyanar, Raja, et al.
Created Date
2014

Battery energy storage has shown a lot of potential in the recent past to be effective in various grid services due to its near instantaneous ramp rates and modularity. This thesis aims to determine the commercial viability of customer premises and substation sited battery energy storage systems. Five different types of services have been analyzed considering current market pricing of Lithium-ion batteries and power conditioning equipment. Energy Storage Valuation Tool 3.0 (Beta) has been used to exclusively determine the value of energy storage in the services analyzed. The results indicate that on the residential level, Lithium-ion battery energy storage may ...

Contributors
Nadkarni, Aditya Dilip, Karady, George G, Ayyanar, Raja, et al.
Created Date
2013

Presently, hard-switching buck/boost converters are dominantly used for automotive applications. Automotive applications have stringent system requirements for dc-dc converters, such as wide input voltage range and limited EMI noise emission. High switching frequency of the dc-dc converters is much desired in automotive applications for avoiding AM band interference and for compact size. However, hard switching buck converter is not suitable at high frequency operation because of its low efficiency. In addition, buck converter has high EMI noise due to its hard-switching. Therefore, soft-switching topologies are considered in this thesis work to improve the performance of the dc-dc converters. Many soft-switching ...

Contributors
Nan, Chenhao, Ayyanar, Raja, Bakkaloglu, Bertan, et al.
Created Date
2016

The reliability assessment of future distribution networks is an important issue in power engineering for both utilities and customers. This is due to the increasing demand for more reliable service with less interruption frequency and duration. This research consists of two main parts related to the evaluation of the future distribution system reliability. An innovative algorithm named the encoded Markov cut set (EMCS) is proposed to evaluate the reliability of the networked power distribution system. The proposed algorithm is based on the identification of circuit minimal tie sets using the concept of Petri nets. Prime number encoding and unique prime ...

Contributors
Almuhaini, Mohammad, Heydt, Gerald, Ayyanar, Raja, et al.
Created Date
2012

As global energy demand has dramatically increased and traditional fossil fuels will be depleted in the foreseeable future, clean and unlimited renewable energies are recognized as the future global energy challenge solution. Today, the power grid in U.S. is building more and more renewable energies like wind and solar, while the electric power system faces new challenges from rapid growing percentage of wind and solar. Unlike combustion generators, intermittency and uncertainty are the inherent features of wind and solar. These features bring a big challenge to the stability of modern electric power grid, especially for a small scale power grid ...

Contributors
Dai, Daihong, Hedman, Kory W, Zhang, Muhong, et al.
Created Date
2014

Scarcity of potable water is one of the major problems faced in the world today. Majority of this problem can be solved if technology is developed to obtain potable water from brackish or saline water. The present desalination methods face challenges such as high costs in terms of energy consumption and infrastructure, physical size of the system, requirement of membrane and high pressure systems and hence have been facing various issues in implementation of the same. This research provides a new low pressure, low energy, portable method to desalinate water without the need for separation membranes, heat or chemical reactions. ...

Contributors
Krishna Kashyap, Suhas, Hui, Joseph, Ayyanar, Raja, et al.
Created Date
2014

In electric power systems, phasor measurement units (PMUs) are capable of providing synchronized voltage and current phasor measurements which are superior to conventional measurements collected by the supervisory control and data acquisition (SCADA) system in terms of resolution and accuracy. These measurements are known as synchrophasor measurements. Considerable research work has been done on the applications of PMU measurements based on the as-sumption that a high level of accuracy is obtained in the field. The study in this dissertation is conducted to address the basic issue concerning the accuracy of actual PMU measurements in the field. Synchronization is one of ...

Contributors
Zhang, Qing, Heydt, Gerald, Vittal, Vijay, et al.
Created Date
2012

After a major disturbance, the power system response is highly dependent on protection schemes and system dynamics. Improving power systems situational awareness requires proper and simultaneous modeling of both protection schemes and dynamic characteristics in power systems analysis tools. Historical information and ex-post analysis of blackouts reaffirm the critical role of protective devices in cascading events, thereby confirming the necessity to represent protective functions in transient stability studies. This dissertation is aimed at studying the importance of representing protective relays in power system dynamic studies. Although modeling all of the protective relays within transient stability studies may result in a ...

Contributors
Hedman, Mojdeh Khorsand, Vittal, Vijay, Ayyanar, Raja, et al.
Created Date
2017

Electric substation physical plans are developed with consideration given to lightning protection. To develop these plans utility design engineers use various methods. This thesis focuses on developing a computer program for two methods/models for substation shielding against direct lightning strokes. The first method is being used currently in the industry to protect the substation structures. The second model is a new and more physics based approach towards lightning phenomenon. Both the methods consider only direct lightning strikes that can hit the substation equipment. Hence, the travelling waves, indirect strokes or over-voltage arriving at the substation equipment are not considered. The ...

Contributors
Marathe, Vinit, Karady, George, Ayyanar, Raja, et al.
Created Date
2016

Solar power generation is the most promising technology to transfer energy consumption reliance from fossil fuel to renewable sources. Concentrated solar power generation is a method to concentrate the sunlight from a bigger area to a smaller area. The collected sunlight is converted more efficiently through two types of technologies: concentrated solar photovoltaics (CSPV) and concentrated solar thermal power (CSTP) generation. In this thesis, these two technologies were evaluated in terms of system construction, performance characteristics, design considerations, cost benefit analysis and their field experience. The two concentrated solar power generation systems were implemented with similar solar concentrators and solar ...

Contributors
Jin, Zhilei, Hui, Yu, Ayyanar, Raja, et al.
Created Date
2013

The government support towards green energy sources for the better future of the planet has changed the perspective of the people towards the usage of green energy. Among renewables, solar is one of the important and easily accessible resources to convert energy from the sun directly into electricity and this system has gained fame since the past three decades. SRP has set up a 6.36 kW PV and 19.4 kWh battery system on the rooftop of Engineering Research Center (ERC). The system is grid-connected and ASU (Arizona State University) has developed two load banks with a minimum step of 72 ...

Contributors
Etha, Pavan, Karady, George, Heydt, Gerald, et al.
Created Date
2017

As residential photovoltaic (PV) systems become more and more common and widespread, their system architectures are being developed to maximize power extraction while keeping the cost of associated electronics to a minimum. An architecture that has become popular in recent years is the "DC optimizer" architecture, wherein one DC-DC converter is connected to the output of each PV module. The DC optimizer architecture has the advantage of performing maximum power-point tracking (MPPT) at the module level, without the high cost of using an inverter on each module (the "microinverter" architecture). This work details the design of a proposed DC optimizer. ...

Contributors
Luster, Daniel, Ayyanar, Raja, Bakkaloglu, Bertan, et al.
Created Date
2014

Insulation aging monitoring is widely used to evaluate the operating condition of power equipment. One important monitoring method is detecting partial discharges (PD). PD is a localized breakdown of dielectric and its characteristics can give information about the insulation aging. Most existing test methods cannot identify different kinds of defects. Also, the practical application of PD detection in most existing test methods is restricted by weak PD signals and strong electric field disturbance from surroundings. In order to monitor aging situation in detail, types of PDs are important features to take into account. To classify different types of PDs, pulse ...

Contributors
Cui, Longfei, Gorur, Ravi, Vittal, Vijay, et al.
Created Date
2013

The safety issue in an electrical power distribution system is of critical importance. In some circumstances, even the continuity of service has to be compromised for a situation that can cause a hazard to the public. A downed conductor that creates an electrical path between a current carrying conductor and ground pose a potential lethal hazard to anyone in the near proximity. Electric utilities have yet to find a fully accepted and reliable method for detecting downed conductors even with decades of research. With the entry of more automation and a smarter grid in the different layers of distribution power ...

Contributors
Abusdal, Geir Magne, Heydt, Gerald T, Ayyanar, Raja, et al.
Created Date
2014

The development of new policies favoring integration of renewable energy into the grid has created a need to relook at our existing infrastructure resources and at the way the power system is currently operated. Also, the needs of electric energy markets and transmission/generation expansion planning has created a niche for development of new computationally efficient and yet reliable, simple and robust power flow tools for such studies. The so called dc power flow algorithm is an important power flow tool currently in use. However, the accuracy and performance of dc power flow results is highly variable due to the various ...

Contributors
Sood, Puneet, Tylavsky, Daniel J, Vittal, Vijay, et al.
Created Date
2014

Optical Instrument Transformers (OIT) have been developed as an alternative to traditional instrument transformers (IT). The question "Can optical instrument transformers substitute for the traditional transformers?" is the main motivation of this study. Finding the answer for this question and developing complete models are the contributions of this work. Dedicated test facilities are developed so that the steady state and transient performances of analog outputs of a magnetic current transformer (CT) and a magnetic voltage transformer (VT) are compared with that of an optical current transformer (OCT) and an optical voltage transformer (OVT) respectively. Frequency response characteristics of OIT outputs ...

Contributors
Kucuksari, Sadik, Karady, George G, Heydt, Gerald T, et al.
Created Date
2010

The electromagnetic fields near power lines that may produce adverse effects on humans are of increasing interest in a variety of situations, thus making it worthwhile to develop general-purpose software that estimates both the electric and magnetic fields accurately. This study deals with the simulations of the electric and magnetic fields near high-voltage power lines for the triangular, horizontal and vertical conductor arrangements under both balanced and unbalanced conditions. For all three conductor arrangements, the shapes of the electric field distribution curves are different with the vertical arrangement best for minimizing right of way consideration, while the shapes of the ...

Contributors
Xiao, Lei, Holbert, Keith E, Karady, George G, et al.
Created Date
2015

Due to increasing integration of renewable resources in the power grid, an efficient high power transmission system is needed in the near future to transfer energy from remote locations to the load centers. Gas Insulated Transmission Line (GIL) is a specialized high power transmission system, designed by Siemens, for applications requiring direct burial or vertical installation of the transmission line. GIL uses SF6 as an insulating medium. Due to unavoidable gas leakages and high global warming potential of SF6, there is a need to replace this insulating gas by some other possible alternative. Insulating foam materials are characterized by excellent ...

Contributors
Pendse, Harshada Ganesh, Karady, George, Holbert, Keith, et al.
Created Date
2014

This thesis concerns the impact of energy storage on the power system. The rapidly increasing integration of renewable energy source into the grid is driving greater attention towards electrical energy storage systems which can serve many applications like economically meeting peak loads, providing spinning reserve. Economic dispatch is performed with bulk energy storage with wind energy penetration in power systems allocating the generation levels to the units in the mix, so that the system load is served and most economically. The results obtained in previous research to solve for economic dispatch uses a linear cost function for a Direct Current ...

Contributors
Gupta, Samir, Heydt, Gerald T, Vittal, Vijay, et al.
Created Date
2012

The past few decades have seen a consistent growth of distributed PV sources. Distributed PV, like other DG sources, can be located at or near load centers and provide benefits which traditional generation may lack. However, distribution systems were not designed to accommodate such power generation sources as these sources might lead to operational as well as power quality issues. A high penetration of distributed PV resources may lead to bi-directional power flow resulting in voltage swells, increased losses and overloading of conductors. Voltage unbalance is a concern in distribution systems and the effect of single-phase residential PV systems on ...

Contributors
Mitra, Parag, Heydt, Gerald T, Vittal, Vijay, et al.
Created Date
2013

Present distribution infrastructure is designed mainly for uni-directional power flow with well-controlled generation. An increase in the inverter-interfaced photovoltaic (PV) systems requires a thorough re-examination of the design, operation, protection and control of distribution systems. In order to understand the impact of high penetration of PV generation, this work conducts an automated and detailed modeling of a power distribution system. The simulation results of the modeled distribution feeder have been verified with the field measurements. Based on the feeder model, this work studies the impact of the PV systems on voltage profiles under various scenarios, including reallocation of the PV ...

Contributors
Tang, Yingying, Ayyanar, Raja, Karady, George, et al.
Created Date
2016

Recent trends in the electric power industry have led to more attention to optimal operation of power transformers. In a deregulated environment, optimal operation means minimizing the maintenance and extending the life of this critical and costly equipment for the purpose of maximizing profits. Optimal utilization of a transformer can be achieved through the use of dynamic loading. A benefit of dynamic loading is that it allows better utilization of the transformer capacity, thus increasing the flexibility and reliability of the power system. This document presents the progress on a software application which can estimate the maximum time-varying loading capability ...

Contributors
Zhang, Ming, Tylavsky, Daniel J, Ayyanar, Raja, et al.
Created Date
2013

This thesis concerns with the impact of renewable generation resources on the power system stability. The rapidly increasing integration of renewable energy sources into the grid can change the way power systems operate and respond to system disturbances. This is because the available inertia from synchronous machines, which helps in damping system oscillations, gets reduced as an increase in renewables like wind and solar photovoltaics is accompanied by a decrease in conventional generators. This aspect of high penetration of renewables has the potential to affect the rotor angle stability and small signal stability of power systems. The system with increased ...

Contributors
Singh, Iknoor, Vittal, Vijay, Ayyanar, Raja, et al.
Created Date
2012

This research presents potential and electric field calculations on medium voltage (MV) epoxy insulated outdoor current transformers (CTs) using a numeri-cal calculation approach. Two designs of MV dry-type epoxy insulated CTs were modeled using 3D field simulation software COULOMB® 9.0. Potential and elec-tric fields were calculated based on boundary element method. Different condi-tions such as dry exterior surface, wet exterior surface and internal voids were considered. The research demonstrates that the presence of internal conductors in CTs results in a less severe surface electric field distribution when compared to outdoor insulators of the same voltage range and type. The high ...

Contributors
Lakshmichand Jain, Sandeep Kumar, Gorur, Ravi, Karady, George, et al.
Created Date
2012

High Voltage Direct Current (HVDC) technology is being considered for several long distance point-to-point overhead transmission lines, because of their lower losses and higher transmission capability, when compared to AC systems. Insulators are used to support and isolate the conductors mechanically and electrically. Composite insulators are gaining popularity for both AC and DC lines, for the reasons of light weight and good performance under contaminated conditions. This research illustrates the electric potential and field computation on HVDC composite insulators by using the charge simulation method. The electric field is calculated under both dry and wet conditions. Under dry conditions, the ...

Contributors
He, Jiahong, Gorur, Ravi S, Gorur, Ravi S, et al.
Created Date
2013

Two significant trends of recent power system evolution are: (1) increasing installa-tion of dynamic loads and distributed generation resources in distribution systems; (2) large-scale renewable energy integration at the transmission system level. A majority of these devices interface with power systems through power electronic converters. However, existing transient stability (TS) simulators are inadequate to represent the dynamic behavior of these devices accurately. On the other hand, simulating a large system using an electromagnetic transient (EMT) simulator is computationally impractical. EMT-TS hybrid simulation approach is an alternative to address these challenges. Furthermore, to thoroughly analyze the increased interactions among the transmission ...

Contributors
Huang, Qiuhua, Vittal, Vijay, Undrill, John M., et al.
Created Date
2016

In modern electric power systems, energy management systems (EMSs) are responsi-ble for monitoring and controlling the generation system and transmission networks. State estimation (SE) is a critical `must run successful' component within the EMS software. This is dictated by the high reliability requirements and need to represent the closest real time model for market operations and other critical analysis functions in the EMS. Tradi-tionally, SE is run with data obtained only from supervisory control and data acquisition (SCADA) devices and systems. However, more emphasis on improving the performance of SE drives the inclusion of phasor measurement units (PMUs) into SE ...

Contributors
Murugesan, Veerakumar, Vittal, Vijay, Heydt, Gerald, et al.
Created Date
2013

An important operating aspect of all transmission systems is power system stability and satisfactory dynamic performance. The integration of renewable resources in general, and photovoltaic resources in particular into the grid has created new engineering issues. A particularly problematic operating scenario occurs when conventional generation is operated at a low level but photovoltaic solar generation is at a high level. Significant solar photovoltaic penetration as a renewable resource is becoming a reality in some electric power systems. In this thesis, special attention is given to photovoltaic generation in an actual electric power system: increased solar penetration has resulted in significant ...

Contributors
Pethe, Anushree Sanjeev, Vittal, Vijay, Heydt, Gerald T, et al.
Created Date
2015

This thesis concerns the flashover issue of the substation insulators operating in a polluted environment. The outdoor insulation equipment used in the power delivery infrastructure encounter different types of pollutants due to varied environmental conditions. Various methods have been developed by manufacturers and researchers to mitigate the flashover problem. The application of Room Temperature Vulcanized (RTV) silicone rubber is one such favorable method as it can be applied over the already installed units. Field experience has already showed that the RTV silicone rubber coated insulators have a lower flashover probability than the uncoated insulators. The scope of this research is ...

Contributors
Gholap, Vipul Ujjiyel, Gorur, Ravi S, Karady, George G, et al.
Created Date
2013

Due to the increasing trend of electricity price for the future and the price reduction of solar electronics price led by the policy stimulus and the technological improvement, the residential distribution solar photovoltaic (PV) system’s market is prosperous. Excess energy can be sold back to the grid, however peak demand of a residential customer typically occurs in late afternoon/early evening when PV systems are not a productive. The solar PV system can provide residential customers sufficient energy during the daytime, even the exceeding energy can be sold back to the grid especially during the day with good sunlight, however, the ...

Contributors
Wang, Xinan, Karady, George G, Smedley, Grant, et al.
Created Date
2016

The high penetration of photovoltaic (PV) both at the utility and at the distribu-tion levels, has raised concerns about the reliability of grid-tied inverters of PV power systems. Inverters are generally considered as the weak link in PV power systems. The lack of a dedicated qualification/reliability standard for PV inverters is a main barrier in realizing higher level of confidence in reliability. Development of a well-accepted design qualification standard specifically for PV inverters will help pave the way for significant improvement in reliability and performance of inverters across the entire industry. The existing standards for PV inverters such as UL ...

Contributors
Alampoondi Venkataramanan, Sai Balasubramanian, Ayyanar, Raja, Vittal, Vijay, et al.
Created Date
2011

Today, more and more substations are created and reconstructed to satisfy the growing electricity demands for both industry and residence. It is always a big concern that the designed substation must guarantee the safety of persons who are in the area of the substation. As a result, the safety metrics (touch voltage, step voltage and grounding resistance), which should be considered at worst case, are supposed to be under the allowable values. To improve the accuracy of calculating safety metrics, at first, it is necessary to have a relatively accurate soil model instead of uniform soil model. Hence, the two-layer ...

Contributors
Wu, Xuan, Tylavsky, Daniel, Undrill, John, et al.
Created Date
2013

Shunt capacitors are often added in transmission networks at suitable locations to improve the voltage profile. In this thesis, the transmission system in Arizona is considered as a test bed. Many shunt capacitors already exist in the Arizona transmission system and more are planned to be added. Addition of these shunt capacitors may create resonance conditions in response to harmonic voltages and currents. Such resonance, if it occurs, may create problematic issues in the system. It is main objective of this thesis to identify potential problematic effects that could occur after placing new shunt capacitors at selected buses in the ...

Contributors
Patil, Hardik Ulhas, Heydt, Gerald T, Karady, George, et al.
Created Date
2015

The standard optimal power flow (OPF) problem is an economic dispatch (ED) problem combined with transmission constraints, which are based on a static topology. However, topology control (TC) has been proposed in the past as a corrective mechanism to relieve overloads and voltage violations. Even though the benefits of TC are presented by several research works in the past, the computational complexity associated with TC has been a major deterrent to its implementation. The proposed work develops heuristics for TC and investigates its potential to improve the computational time for TC for various applications. The objective is to develop computationally ...

Contributors
Balasubramanian, Pranavamoorthy, Hedman, Kory W, Vittal, Vijay, et al.
Created Date
2016

The dissertation encompasses the transformer-less single phase PV inverters for both the string and microinverter applications. Two of the major challenge with such inverters include the presence of high-frequency common mode leakage current and double line frequency power decoupling with reliable capacitors without compromising converter power density. Two solutions are presented in this dissertation: half-bridge voltage swing (HBVS) and dynamic dc link (DDCL) inverters both of which completely eliminates the ground current through topological improvement. In addition, through active power decoupling technique, the capacitance requirement is reduced for both, thus achieving an all film-capacitor based solution with higher reliability. Also ...

Contributors
Roy, Jinia, Ayyanar, Raja, Karady, George, et al.
Created Date
2017

Two major challenges in the transformer-less, single-phase PV string inverters are common mode leakage currents and double-line-frequency power decoupling. In the proposed doubly-grounded inverter topology with innovative active-power-decoupling approach, both of these issues are simultaneously addressed. The topology allows the PV negative terminal to be directly connected to the neutral, thereby eliminating the common-mode ground-currents. The decoupling capacitance requirement is minimized by a dynamically-variable dc-link with large voltage swing, allowing an all-film-capacitor implementation. Furthermore, the use of wide-bandgap devices enables the converter operation at higher switching frequency, resulting in smaller magnetic components. The operating principles, design and optimization, and control ...

Contributors
Xia, Yinglai, Ayyanar, Raja, Karady, George, et al.
Created Date
2017

The growth of energy demands in recent years has been increasing faster than the expansion of transmission facility construction. This tendency cooperating with the continuous investing on the renewable energy resources drives the research, development, and construction of HVDC projects to create a more reliable, affordable, and environmentally friendly power grid. Constructing the hybrid AC-HVDC grid is a significant move in the development of the HVDC techniques; the form of dc system is evolving from the point-to-point stand-alone dc links to the embedded HVDC system and the multi-terminal HVDC (MTDC) system. The MTDC is a solution for the renewable energy ...

Contributors
Yu, Jicheng, Karady, George, Qin, Jiangchao, et al.
Created Date
2017

Alternate sources of energy such as wind, solar photovoltaic and fuel cells are coupled to the power grid with the help of solid state converters. Continued deregulation of the power sector coupled with favorable government incentives has resulted in the rapid growth of renewable energy sources connected to the distribution system at a voltage level of 34.5kV or below. Of late, many utilities are also investing in these alternate sources of energy with the point of interconnection with the power grid being at the transmission level. These converter interfaced generation along with their associated control have the ability to provide ...

Contributors
Ramasubramanian, Deepak, Vittal, Vijay, Undrill, John, et al.
Created Date
2017

There has been a considerable growth in distributed photovoltaic (PV) genera-tion and its integration in electric power distribution systems. This has led to a change in the distribution system infrastructure. Properly planned distributed gen-eration can offer a variety of benefits for system operations and enhance opera-tional performance of the distribution system. However, high penetration of PV resources can give rise to operating conditions which do not arise in traditional systems and one of the potential issues that needs to be addressed involves impact on power quality of the system with respect to the spectral distortion in voltages and currents. The ...

Contributors
Joshi, Titiksha Vjay, Heydt, Gerald T, Ayyanar, Raja, et al.
Created Date
2014

An advantage of doubly fed induction generators (DFIGs) as compared to conventional fixed speed wind turbine generators is higher efficiency. This higher efficiency is achieved due to the ability of the DFIG to operate near its optimal turbine efficiency over a wider range of wind speeds through variable speed operation. This is achieved through the application of a back-to-back converter that tightly controls the rotor current and allows for asynchronous operation. In doing so, however, the power electronic converter effectively decouples the inertia of the turbine from the system. Hence, with the increase in penetration of DFIG based wind farms, ...

Contributors
Gautam, Durga, Vittal, Vijay, Heydt, Gerald, et al.
Created Date
2010

Constraint relaxation by definition means that certain security, operational, or financial constraints are allowed to be violated in the energy market model for a predetermined penalty price. System operators utilize this mechanism in an effort to impose a price-cap on shadow prices throughout the market. In addition, constraint relaxations can serve as corrective approximations that help in reducing the occurrence of infeasible or extreme solutions in the day-ahead markets. This work aims to capture the impact constraint relaxations have on system operational security. Moreover, this analysis also provides a better understanding of the correlation between DC market models and AC ...

Contributors
Salloum, Ahmed, Vittal, Vijay, Hedman, Kory, et al.
Created Date
2016

This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries.

For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.