Simultaneous Optimization of Hydropower Penetration Level and Power Factor to Improve Power Quality in the 20 kV Kuala-Binjai Distribution Network

This paper investigates the technical impact of hydropower-based distributed generation (DG) integration on the Kuala-Binjai 20 kV distribution subsystem in North Sumatra, Indonesia. The study focuses on the combined effect of DG penetration level and generator power factor on network performance under steady-state operating conditions. The analyzed system is supplied by the Binjai High Voltage Substation and interconnected with the Batugajah Hydropower Plant. Using ETAP-based load flow simulation, the base-case condition and multiple operating scenarios were evaluated in terms of power quality, specifically focusing on voltage profile and active power losses, while also considering undervoltage conditions and power flow characteristics. The results show that the relationship between DG penetration and system performance is non-linear. As the penetration level increases, active power loss decreases significantly up to an optimum point, beyond which the losses increase again. The minimum active power loss is obtained at a penetration level of approximately 64% under a power factor of 0.94, with a loss value of 0.748 MW. From the voltage perspective, increasing hydropower penetration improves feeder voltage support substantially, reducing the number of undervoltage buses from more than 500 buses at low penetration levels to as low as 38 buses at 70% penetration under lagging power factor operation. However, extreme leading power factor conditions degrade both loss and voltage performance. Overall, the recommended operating region is identified at approximately 60% - 70% penetration with near-unity power factor, which provides the best balance between loss minimization and acceptable voltage performance.