Improvement To Hif Detection and Isolation In Ungrounded Delta Systems Utilizing Existing Infrastructure

High impedance faults (HIFs) pose significant risks in electrical systems including wildfires, equipment damage, loss of wildlife, and threats to reliability. To mitigate these risks, utilities must implement advanced detection techniques and monitoring systems to identify and isolate HIFs early on, specifically in unground delta systems. The behaviors and characteristics of HIFs are difficult to detect by traditional overcurrent protection devices due to their ability to draw low current. Proactive approaches such as (1) comparing phase relationship between residual voltage and residual current using zero-sequence capacitive impedance and (2) using zero-sequence voltage to indicate existence of phase to ground faults using line-to-ground charging capacitance are analyzed for sensitivity, selectivity, and speed. This work demonstrates the effectiveness of incorporating these methodologies into existing infrastructure and hardware with minimal modifications. Simulations performed using RTDS on 4.8kV ungrounded delta systems in correctly identifying faulted feeder. Future recommendations for enhanced confidence include testing with downed energized primary conductors prior to field implementation.