Enhancing Stability of the Kalimantan Interconnection After Ketapang Subsystem Integration Using PSS Optimization

The integration of the Ketapang subsystem (West Kalimantan) into the main Interconnection System (Central, South, and East Kalimantan) has raised concerns regarding inter-area stability. Power System Stabilizers (PSS) had previously been implemented at four power plants : PLTU SLK, PLTU TPI, PLTU GPK, and PLTU Asam-Asam 56. Under base conditions (prior to the Ketapang integration), the system's damping ratio was approximately 5; however, the integration of Ketapang led to a decrease in the damping ratio to around 2.1. To address this, an optimization strategy utilizing the Fast Fourier Transform (FFT) within the DIgSILENT Power Factory simulator was employed, yielding new optimized PSS settings that restored the damping ratio to approximately 5. Additionally, a study was conducted on the implementation of new PSS units at power plants exhibiting high participation factors in the inter-area oscillations, namely PLTU Teluk Balikpapan, PLTU Indoeka, and PLTU Asam-Asam Units 1-4. By applying optimized settings to these newly added PSS units, the damping ratio was further increased to values exceeding 10. Alongside modal analysis simulations, RMS contingency simulations were also performed to verify the accuracy of the optimized PSS settings. The damping ratio results were as follows: 2.44 for the base condition (Modal analysis: 2.64), 4.87 for the optimized existing PSS setting (Modal analysis: 5.44), and 9.41 for the additional PSS optimization (Modal analysis: 10.11).