Monitoring-Based Localization of Unbalances and Root Cause Analysis in Low-Voltage Distribution Systems

Abstract

The dynamic nature of power systems operation, lack of sufficient monitoring initiatives, and the continuous nature of the power quality phenomena are the primary reasons behind a distribution system operator's inability to localize and understand the root cause behind unbalance. Additionally, there is a deficiency of algorithms that can leverage the grid monitoring data, even if limited, to present a sufficiently useful overview of unbalance propagation which can lead to appropriate corrective measures. This article presents: a new unbalance index derived from feeder active power measurements, an algorithm for localization of unbalanced contributions, and an algorithm for root cause analysis that can distinguish whether the unbalance problem is loading, asymmetry, and/ or fault-oriented. The end goals of this work are twofold: to present a holistic view of the grid unbalanced situation using EN50160 type monitoring, and to assist the distribution system operators in unbalance reduction. The usability of the proposed algorithms and indices is shown using a hybrid European MV-LV model simulated in OpenDSS and on two actual LV distribution systems with real-time power quality monitoring.