Faults and Voltage Sag Fundamentals

Apuntes

[Diapositiva 1] Utility Applications of Power Electronics The University of Tennessee, Knoxville ECE 625 Lecture #4 – Faults, Sags, and Outages Reliability and Resilience January 28, 2026 [Diapositiva 2] Announcements 2 Homework #1 – due Friday, Jan. 30, 9 am, Canvas 2 [Diapositiva 3] Outline 3 Faults on the grid Voltage sags Reliability outage indices and calculations Resiliency indices Example to improve resiliency and reliability 3 [Diapositiva 4] Transmission Line Models RL model π model T model Distributed model GCU, Model of transmission lines 4 [Diapositiva 5] Transmission Line Fault Cases Three-phase fault (L-L-L) Balanced faults Three-phase-to-ground fault (LLL-G) Unbalanced faults Line-to-line fault (L-L) Line-to-ground fault (L-G) Line-to-line-to-ground fault (L-L-G) 5 [Diapositiva 6] Voltage Sags Most voltage sags are caused by faults on the electric grid. The voltage at “bolted” faults is zero at the point of the fault. Voltage sags are characterized by their magnitude and duration. Typically in a radial system (feeder), if a fault occurs directly upstream from the point of interest (POI), the voltage at the POI is zero. If the fault occurs downstream of the POI, t...