School of Electrical, Computer and Energy Engineering

M.S. Final Oral Defense

Development of the Selection Procedure of an Insulating Foam for Its Application in Gas Insulated Transmission Lines, Demonstrated Using Syntactic Foam

by

Harshada Ganesh Pendse

10/24/2014

3 p.m.

ERC 490

Committee:

Dr. George Karady (chair)

Dr. Keith Holbert

Dr. Raja Ayyanar

Abstract

Due to increasing integration of regenerative 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 dielectric properties as well as their reduced weight. These materials can find their application in GIL as high voltage insulators. One of the example of polymer based insulating foam is syntactic foam. It consists of a large number of microspheres embedded in a polymer matrix.

The work in this thesis deals with the development of the selection procedure for an insulating foam for its application in GIL. All the steps in the process are demonstrated considering syntactic foam as an insulator. As the first step of the procedure, a small representative model of the insulating foam is built in COMSOL Multiphysics software with the help of AutoCAD and Excel VBA to analyze electric field distribution for the application of GIL. The effect of the presence of metal particles on the electric field distribution is also observed. The AC voltage withstand test is performed on the insulating foam samples according to the IEEE standards. The effect of the insulating foam on electrical parameters as well as transmission characteristics of the line is analyzed as the last part of the thesis. The results from all the simulations and AC voltage withstand test are observed to predict the suitability of the syntactic foam as an insulator in GIL.