Analysis of Protection System Based On-Line Current Differential Using Nominal Phi Method on 150 Kv Transmission Line Ngimbang-Babat 1

An electric power system is often faced with disturbance problems. The 150 kV transmission line from GI Ngimbang to GI Babat 1 experienced several disturbances due to a single-phase short circuit to the ground. The approach to determining the value of the impedance is by considering the value of the capacitance using the Phi Nominal Method with the center of the capacitance value located at the ends of the line which is divided equally in size. The main protection system used on the transmission line is the Distance relay, but the Distance relay is still not reliable and responsive. So with these shortcomings, it can be overcome by using a Line Current Differential transmission line protection system, it is proven that the Differential Line Current performance can work well. The research was conducted to analyze the performance of the Line Current Differential protection relay on the 150 kV Ngimbang-Babat 1 transmission line by calculating the impedance and capacitance values. The calculation is simulated in modeling the system against short circuit faults in determining the protection relay settings. From the results of the study, it was found that the accuracy of the Line Current Differential setting value can work by providing a disturbance signal to the power breaker (PMT) to perform tripping when a disturbance occurs in an area that is secured by a protection relay (internal fault), while the protection relay cannot work when an external disturbance occurs. secured area protection relay(external fault).