Study of Overcurrent Relay Settings for the Bakaru Hydroelectric Generator and Transformer Protection System Before and After the Entry of the Malea Hydroelectric Power Plant

Abstract

The addition of new generators causes changes in short circuit current when a disturbance occurs in the electric power system which requires increased performance of the protection system, especially in overcurrent relays. This research discusses the impact of adding power plants to the electric power system and the need to adjust the overcurrent relay settings in the generator protection system of the Bakaru Hydroelectric Power Plant before and after the inclusion of the Malea Hydroelectric Power Plant, with a power of 2 x 45 MW, into the SULBAGSEL system. The data used is PT electrical system data. PLN (Persero) UP2B Makassar, PT. PLN (Persero) UIKL Sulawesi, and ULPLTA Bakaru. This study involves a simulation analysis of power flow and short circuit disturbances on the Bakaru 150 kV busbar with two case scenarios using the DigSilent program. The first case compares the nominal current and overcurrent relay settings on the generator, while the second case compares the short circuit current on the busbar. The simulation results show that the short circuit current on the Bakaru 150 kV busbar before and after the entry of the Malea Hydroelectric Power Plant is 4,395 kA and 4,421 kA, showing a significant increase. Furthermore, the overcurrent relay settings on the Bakaru PLTA unit 1 and unit 2 generators before the Malea PLTA entered were 3.34 kA and 3.14 A, which then reduced to 3.15 A and 2.97 A after the Malea PLTA entered.