Enhanced Earth Fault Detection in Power Systems Using Neutral Voltage Displacement Method

Abstract

The zeal to swiftly detect and isolate a faulty section of the power system is very important if the system is to be described as a reliable one. In achieving this a prototype Distribution Board Earth Fault Detection System (DBEFDS) was designed and constructed based on single-phase scenario using Neutral Voltage Displacement (NVD) method. This was done because the system is symmetrical. Neutral Voltage Displacement (NVD), Directional Overcurrent (DO), and Distance Protection (DP) in fault detection algorithm were also compared in terms of time response during fault. At the maximum distance of 50km, neutral voltage displacement detected fault at 1.10 seconds while distance protection and directional overcurrent detected fault at 0.83 seconds and 0.55 seconds respectively. Faults at 0km, 5km, 10km, 15km, 20km, 25km, 30km, 35km, 40km, 45km, and 50km were detected at 0.10s, 0.20s, 0.30s, 0.40s, 0.50s, 0.60s, 0.70s, 0.80s, 0.90s, 1.00s and 1.10s respectively, using neutral voltage displacement method. Faults at 0km, 5km, 10km, 15km, 20km, 25km, 30km, 35km, 40km, 45km, and 50km were detected at 0.08s, 0.15s, 0.23s, 0.30s, 0.38s, 0.46s, 0.53s, 0.60s, 0.68s, 0.75s and 0.83s respectively, using distance protection method. Faults at 0km, 5km, 10km, 15km, 20km, 25km, 30km, 35km, 40km, 45km, and 50km were detected at 0.05s, 0.10s, 0.15s, 0.20s, 0.25s, 0.30s, 0.40s, 0.45s, 0.50s and 0.55s respectively, using directional over current method. It was noted that single-line-to-ground fault recorded 500Ω in dry land and 300Ω in wet land and by this, earth fault was detected at 0.10s within the premises using neutral voltage displacement method. This method has proven to provide earth fault detection time for the safety of lives and equipment as provided in IEEE regulation.