Feeder Open-Phase Detection by Smart Inverters

Inadvertent open phase condition is a concern for distributed energy resources (DER) integration, due to the unregulated voltage on the opened phase. Although IEEE 1547–2018 standard mandates DER to detect and trip for open phase condition at its reference point of applicability (RPA), it may be challenging for DER to detect a feeder (high side of interconnection transformer) open phase condition. This paper presents an improved feeder open phase detection (OPD) method that only utilizes the solar photovoltaic (PV) or energy storage inverter's onboard resources. Controller hardware-in-the-loop (CHIL) results are shown to demonstrate the effectiveness of the proposed OPD algorithm. It is found that the OPD method can successfully detect a feeder open phase condition for $\Delta/\mathbf{Yg}$, YgNg, and $\Delta/\Delta$ transformer, but not with $\mathbf{Yg}/\Delta$ transformer.