Voltage Stability through Over Voltage Transmission Shedding Case Study: Interconnection between Central Kalimantan System and Ketapang System

This paper addresses voltage stability issues
arising from the interconnection between the Central
Kalimantan and Ketapang systems, which possess significantly
different voltage characteristics. Central Kalimantan operates
at high voltage with a radial transmission structure and a 200
MW main power plant located far from the load center, while
the Ketapang system is a low-voltage network with limited
generation capacity and high sensitivity to reactive power
variations. The 149 km transmission line connecting both
systems contributes to the occurrence of overvoltage
phenomena, particularly during disturbances. Through
sensitivity analysis, Sandai and Sukadana substations in the
Ketapang system showed the highest ΔV/ΔQ values of 0.00448
and 0.00308 p.u/MVAR, respectively, indicating a high
vulnerability to voltage fluctuations. To mitigate these issues, a
revised over voltage transmission shedding (OVTS) scheme was
implemented, incorporating reset OVTS thresholds (e.g.,
109.3% for Sampit–Pangkalan Bun) and expanded coverage
across new target lines. Simulation and field data show that the
updated OVTS scheme effectively prevents voltage surges up to
176 kV during events such as 44 MW generation loss and reactor
disconnections. This study presents a novel OVTS configuration,
optimized through Q-V sensitivity analysis, to mitigate
overvoltage risks in the recently connected Central Kalimantan-
Ketapang Grid.