Adaptive Settings of Distance Relays in the Presence of Flexible Alternating Current Transmission System (FACTS) Devices in the Nigeria Transmission Network

Abstract

The Flexible Alternating Current Transmission System (FACTS) devices affect the performance of the pre-existing protective distance relay on the transmission line. These devices would affect both the steady state and transient trajectory of the apparent impedance seen by distance relays due to the fast response time of the FACTS controllers with respect to that of the protective devices. The simulation model of the Thyristor Controlled Series Capacitor (TCSC), a series FACTS device was simulated in the Nigeria power system using MATLAB/ Simulink software. The apparent impedance of the Nigeria 330kv transmission network was calculated based on the method of symmetrical components of voltage and current. This ultimately set the trip boundaries of a mho-type distance relay. The results from the case study for a single line to ground fault at various locations were generated from system modelling and simulations for conditions without TCSC, with TCSC and with Metal Oxide Varistor (MOV) protection. The proposed adaptive relay algorithm was used in adjusting the settings of the relay to accurately trip with respect to the location and direction of faults in the Nigeria power system.