ASU Electronic Theses and Dissertations
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.
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- All Subjects: Electric Fields
- Creators: Vittal, Vijay
Description
Electric utilities are exploring new technologies to cope up with the in-crease in electricity demand and power transfer capabilities of transmission lines. Compact transmission lines and high phase order systems are few of the techniques which enhance the power transfer capability of transmission lines without requiring any additional right-of-way. This research work investigates the impact of compacting high voltage transmission lines and high phase order systems on the surface electric field of composite insulators, a key factor deciding service performance of insulators. The electric field analysis was done using COULOMB 9.0, a 3D software package which uses a numerical analysis technique based on Boundary Element Method (BEM). 3D models of various types of standard transmission towers used for 230 kV, 345 kV and 500 kV level were modeled with different insulators con-figurations and number of circuits. Standard tower configuration models were compacted by reducing the clearance from live parts in steps of 10%. It was found that the standard tower configuration can be compacted to 30% without violating the minimum safety clearance mandated by NESC standards. The study shows that surface electric field on insulators for few of the compact structures exceeded the maximum allowable limit even if corona rings were installed. As a part of this study, a Gaussian process model based optimization pro-gram was developed to find the optimum corona ring dimensions to limit the electric field within stipulated values. The optimization program provides the dimen-sions of corona ring, its placement from the high voltage end for a given dry arc length of insulator and system voltage. JMP, a statistical computer package and AMPL, a computer language widely used form optimization was used for optimi-zation program. The results obtained from optimization program validated the industrial standards.
ContributorsMohan, Nihal (Author) / Gorur, Ravi S. (Thesis advisor) / Heydt, Gerald T. (Committee member) / Vittal, Vijay (Committee member) / Arizona State University (Publisher)
Created2012
Description
This research work illustrates the use of software packages based on the concept of nu-merical analysis technique to evaluate the electric field and voltage distribution along composite insulators for system voltages ranging from 138 kV up to 1200 kV ac. A part of the calculations was made using the 3D software package, COULOMB 8.0, based on the concept of Boundary Element Method (BEM). The electric field was calculated under dry and wet conditions. Compo-site insulators experience more electrical stress when compared to porcelain and are also more prone to damage caused by corona activity. The work presented here investigates the effect of corona rings of specific dimensions and bundled conductors on the electric field along composite insulators. Inappropriate placement or dimensions of corona rings could enhance the electric field instead of mitigating it. Corona ring optimization for a 1000 kV composite insulator was per-formed by changing parameters of the ring, such as the diameter of the ring, thickness of the ring tube and the projection of the ring from the high voltage energized end fitting. Grading rings were designed for Ultra High Voltage (UHV) systems that use two units of composite insulators in pa-rallel. The insulation distance, which bears 50% of the total applied voltage, is raised by 61% with the grading ring installed, when compared to the distance without the grading ring. In other words, the electric field and voltage distribution was found to be more linear with the application of grad-ing rings. The second part of this project was carried out using the EPRI designed software EPIC. This is based on the concept of Charge Simulation method (CSM). Comparisons were made be-tween electric field magnitude along composite insulators used for suspension and dead end configuration for system voltages ranging from 138 kV to 500 kV. It was found that the dead end composite insulators experience significantly higher electrical stress when compared to their suspension counterpart. It was also concluded that this difference gets more prominent as the system voltage increases. A comparison made between electric field distribution along composite insulators used in single and double dead end structures suggested that the electric stress experienced by the single dead end composite insulators is relatively higher when compared to double dead end composite insulators.
ContributorsDoshi, Tanushri (Author) / Gorur, Ravi S (Thesis advisor) / Vittal, Vijay (Committee member) / Farmer, Richard (Committee member) / Arizona State University (Publisher)
Created2010