Operational stability of cascade hydropower stations under load disturbances

The joint operation of cascade hydropower stations presents a complex challenge, involving multiple hydropower facilities interconnected hydraulically. Currently, the operational stability of such cascading systems remains uncertain. This study examines the operational stability of two hydropower stations linked by a small-volume regulating reservoir (THS-CRR). Initially, a mathematical model for THS-CRR is developed. Subsequently, the stability of hydropower stations with varying hydraulic connections is analyzed. Additionally, the impact of hydraulic links on operational stability is elucidated. Finally, recommendations for selecting governor parameters are provided. The findings suggest that hydraulic links between cascade hydropower stations may compromise stability, as fluctuations in the water level of the regulating reservoir influence the power output of the downstream station. Specifically, when water level variations counteract discharge changes, the system struggles to maintain discharge balance and meet load demands, resulting in instability. To enhance stability, using smaller governor parameters for the upstream station and larger ones for the downstream station is advisable.