Reoperation of hydro–hydrogen–dominated hybrid energy systems to adapt to ecological uncertainty

Hybrid energy systems have become a promising strategy for enhancing power utilization efficiency while preserving ecology. Previous research has predominantly focused on developing models with fixed ecological constraints. However, the fixed ecological constraints overlook dynamic ecological uncertainty and its interaction with operation decisions. This study proposes adaptive operating rules for hydro–hydrogen–wind–photovoltaic (HHWP) hybrid energy systems that explicitly incorporate ecological uncertainty. Initially, the ecological uncertainty is characterized by using boundaries of ecological flow. After that, a discrete set of ecological uncertainty levels is incorporated into the operation model to simultaneously maximize operating benefit and guaranteed rate. Finally, adaptive operating rules are derived considering the interaction between decision variables and ecological uncertainty. A case study of China's Ertan HHWP hybrid energy system demonstrates that reservoir release is the principal decision variable for optimizing operating benefits and guaranteed rate. The ecological operating rules increase operating benefits by 15.80% (from 3.86 to 4.47 billion CNY), boost the guaranteed rate by 5.54% (from 89.32% to 94.27%), and reduce ecological alteration by 50% (from 0.08 to 0.04), compared to traditional strategies. This study highlights the potential of adaptive ecological operating rules in balancing energy efficiency and ecological sustainability.