Effect of Line Splitting by New Substation on 500kV Transmission Line Compensated at One End

This study is performed to determine the transient characteristic of 500kV transmission line in Java-Bali grid which is split into two segment due to construction of new substation in the middle of transmission line. The new substation is intended to increase the reliability of system to comply with load demand growth. Splitting of existing transmission line probably causes one of the segments experience over compensation, because the existing shunt reactor on the transmission line is still used to reduce the system voltage during energize and switching process. While the other transmission line segment does not require any shunt reactor based on load flow analysis that has been performed. Splitting of existing transmission line also causes only one transpose in each segment of transmission line, so it is not effective in minimizing the mutual inductive and capacitive coupling on the transmission line. The objectives of the study are ensuring the success of auto reclose scheme on each transmission line segment and minimizing the probability of equipment breakdown due to overvoltage during single phase to ground fault and open phase fault on both of transmission line segments. The study is performed by doing calculation and simulation in transient analysis application based on data in existing and future system conditions.