Transposition and Voltage Unbalance in High Phase Order Power Transmission Systems

Abstract

—High phase order systems have been proposed at the early inception of power transmission engineering, but few direct applications have been made. High phase order transmission should be considered as an alternative in the case of high power density applications. In this article, an analysis of transposition of high phase order overhead transmission lines is presented and voltage unbalance in high phase order systems is considered. Definitions are presented for “fully transposed” and “roll transposed” along with advantages and disadvantages of each. A generalized voltage unbalance factor is introduced and utilized to determine the benefits of transposition. The generalized voltage unbalance factor is compared with three other possible unbalance factors to determine if the generalized voltage unbalance factor is an appropriate indication of unbalance. Exemplary results are presented for 6-phase and 12-phase designs. Conclusions show that the generalized voltage unbalance factor is a good indication of transmission line voltage unbalance and certain configurations may not need full rotation transposition to minimize the unbalance factor. The transposition analysis and voltage unbalance are considerations in the assessment of high phase order as a high power transmission alternative.

Keywords:

• power transmission
• transmission engineering
• high phase order
• 6-phase
• 12-phase
• transmission line transposition
• transposition
• voltage unbalance factor
• voltage unbalance

Additional information

Funding

The authors acknowledge the support of the Power Systems Engineering Research Center (PSerc), which is a Generation III National Science Foundation Industry University Cooperative Research Center (awards EEC-0001880 and EEC-0968993). The authors also acknowledge the support of the U.S. Department of Energy for its PSERC future grid initiative.

Notes on contributors

Brian J. Pierre

Brian J. Pierre is from Laramie, WY, USA. He holds a BSEE from Boise State University, Boise, ID (2011), where he was president of the Electrical Engineering Honors Society and Eta Kappa Nu (HKN). He holds an MSEE from Arizona State University, Tempe, AZ (2013). He has industrial experience with Schweitzer Engineering Laboratories, Pullman, WA, and Boise, ID, and NASA Glenn Research Center, Cleveland, OH. He is presently a doctoral student at Arizona State University.

Gerald T. Heydt

Gerald T. Heydt is from Las Vegas, NV, USA. He holds a Ph.D. in electrical engineering from Purdue University (1971). He is presently a Regents’ Professor at Arizona State University, Tempe, AZ. His interests are in transmission and distribution engineering. He is a member of the National Academy of Engineering and a life fellow of the IEEE.