White Papers

Applications for Phase-Shifting Transformers in Rural Power Systems

By Thomas Morrell and Jeff Eggebraaten, POWER Engineers


The use of phase-shifting transformers (PST) to control real-power flow can take advantage of financial incentives, meet contractual import or export obligations, or prevent the exceedance of line rating constraints. Millennium Challenge Account Nepal (MCA-N) requested that a PST be sized to control power-flow at the Indian-Nepal border. This paper first provides a summary of PST theory and design. Then, various methods of specifying the phase shift and through power rating of a PST are explored, such as the capacity to prevent the simultaneous import and export of real-power by one balancing authority. A method of modeling a PST in PSS/E is also described as well as case creation for a loop-flow scenario. This paper concludes with the sizing methodology chosen by the authors along with a technical explanation. As a case study, a feasibility study between Nepal and India is analyzed.

This paper was presented at the 2019 IEEE REPC Conference.

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