Residual current-based method for open phase detection in radial and multi-source power systems

Abstract

Open phase conditions typically result in very low fault currents which makes their detection using the existing conventional protective relaying schemes very difficult. This paper proposes a new current-only Open Phase Detection (OPD) scheme suitable for effectively grounded distribution networks. The proposed OPD approach is based on the prevailing current imbalance in the network. Reference phase currents are calculated (predicted) online using Residual Current Multiplying Factors (RCMFs), and are afterwards compared with the measured phase currents. A mismatch between the predicted reference phase currents and the measured phase currents is used as an indication of an open conductor event.Extensive studies were performed using a distribution network modelled in RSCAD software. The performance of the proposed protection scheme was validated using the Real-Time Digital Simulator (RTDS) for various open phase events and non-open phase conditions. The experimental results obtained validate the effectiveness of the proposed OPD scheme.