Voltage unbalance with a phase out of service in polyphase transmission systems

High phase order transmission systems (e.g., nφ ≥ 6) are revisited with a specific focus: the operation of a polyphase system with one phase out of service. The resulting voltage at the load end of the circuit is considered for voltage unbalance calculation. Envisioned are temporary outages to allow repairs of one phase. The concept of single pole switching for stability enhancement of a three-phase system during a single phase fault can be found in literature. This paper specifically focusses on voltage unbalance in a high phase order system for the case of one phase out of service. Simulation results are presented.