Frequency regulation analysis of the Coca Codo Sinclair hydropower plant (Ecuador) in isolated operation with high wind power penetration

Resumen

The increasing integration of wind energy into isolated power systems presents significant challenges for frequency regulation, particularly in regions where renewable penetration is expected to rise. This paper analyzes the frequency control capabilities of the Coca Codo Sinclair Hydropower Plant under such conditions, proposing a systematic methodology for tuning the gains of its speed governor. A dynamic model of the plant is developed in Matlab Simulink, explicitly incorporating long penstocks and hydraulic coupling between generating units, a configuration rarely addressed in conventional tuning approaches. The tuning strategy is based on minimizing a performance penalty index that reflects the plant's response to power disturbances. Two gain-setting approaches are evaluated: one that adapts to the operational configuration of the generation units, and another that uses fixed gains regardless of operating mode. Simulation results, aligned with national renewable expansion plans, show that both strategies improve frequency stability compared to conventional tuning. The mode-dependent tuning yields better performance in reducing frequency deviations, while the fixed-gain approach simplifies implementation but may increase mechanical stress on turbine components. The results demonstrate that a suitable methodology for tuning speed controller gains in isolated systems with complex hydraulic dynamics enhances system performance, even under high wind power penetration levels. Moreover, these results highlight the importance of realistic modeling and adaptive tuning in the reliable integration of renewable energy in remote and decarbonization-priority areas.