Multi-Timescale Hydro Modeling with Integrated Hydrological Conditions: Flexibility Analysis and Its Impact on Grid Stability

Hydropower, known for its rapid power response capabilities, is crucial in providing flexibility and improving grid stability amid increasing penetration of Inverter-based Resources. Current hydropower modeling for flexibility and stability analysis assumes a constant water head, potentially misestimating hydropower capability in energy and ancillary service, while single-or dual-timescale optimization models fail to assess its impacts in real-time dynamic stability analysis. Therefore, accurate modeling of multi-timescale hydropower for flexibility analysis and its impact on grid stability remains challenging. This study proposes a multi-timescale hydropower model that integrates realistic hydrological data into the day-ahead unit commitment, real-time economic dispatch, and dynamic stability models. Using the 240-bus Western Electricity Coordinating Council test system, the study demonstrates that accounting for hydrological conditions improves the accuracy of hydropower modeling in flexibility, accurately estimates hydropower's capability to provide energy, primary frequency regulation, and automatic generation control. Additionally, its impact on grid frequency stability is successfully validated through the dynamic stability analysis.