Lombok electrical system has been operating a 150kV high voltage transmission line and has been developing continuously. High voltage transmission line construction is an effort to improve electrical system quality and reliability. Thus, good protection is needed to maintain the distribution reliability of electrical power. One of the relays used in the Lombok electrical protection system is a distance relay. Distance relay works as the main protection in the transmission system by measuring fault impedance value based on current and voltage detected by the relay.
This study illustrates how to calculate distance relay setting impedance in Z1pri, Z2pri and Z3pri then held a short-circuit simulation in software ETAP 7.5 to examine it.
Setting calculation result of distance relay in Ampenan for Ampenan – Jeranjang line protection, with 3,25 Ω (7.543 km)line impedance, is Z1pri = 2.6057 Ω (6.0345 km), t1 = 0 second, Z2pri = 13.7056 Ω (31.7406 km), t2 = 0.4 second, Z3pri = 24.7209 Ω (57.2508 km), t3 = 1.2 second. Relay’s setting impedance is larger than fault impedance detected by the relay, so that distance relay has been able to protect the system. This study may also show graphic of setting impedance and time coordination from distance relay for every protection area section.
DISTANCE RELAY PROTECTION COORDINATION ANALYSIS OF HIGH VOLTAGE TRANSMISSION LINE 150 KV LOMBOK POWER SYSTEM
