Unit Commitment with 2-Minute Fast Frequency Reserve Constraint in the Jawa-Madura-Bali Power System

The increasing penetration of intermittent renewable energy sources poses significant challenges to maintaining frequency stability in power systems. This paper presents an enhanced Unit Commitment (UC) optimization model that incorporates a 2-minute Fast Frequency Reserve (FFR) constraint to improve system reliability. The study focuses on the Jawa-Madura-Bali (JAMALI) interconnected power system, with a total installed capacity of 48,721 MW. The proposed model considers generator technical characteristics, Automatic Generation Control (AGC) participation, and the System Stiffness Index (SSI) derived from historical frequency disturbance data. Two scenarios are evaluated: a baseline case without the 2-minute FFR constraint and a case with FFR integration. Results indicate that to mitigate a 1000 MW generator loss, the JAMALI system must provide at least 675 MW of FFR to restore frequency to 49.8 Hz within two minutes. Including a 2-minute FFR requirement to the model shifts the generation mix, reducing coal-fired generation and increasing combined-cycle gas usage. This operational change increases total cost from IDR 475.48 billion to IDR 476.85 billion due to greater reliance on flexible generators. Sensitivity analysis shows that increasing coal unit AGC participation from 69 to 100 allows greater use of cost-effective coal generation, lowering costs by IDR 0.57 billion. Dynamic frequency response simulations demonstrate that the proposed model with 675 MW of 2-minute FFR achieves improved steady-state frequency recovery after the largest generation loss event, reaching 49.825 Hz and 49.815 Hz for 69 and 100 AGC participation, respectively, within two minutes. © 2025 IEEE.