Adaptive operating rules for mitigating energy droughts in large-scale hydro-wind-solar complementary systems

Large-scale hydro-wind-solar complementary systems (HWSCSs) present a promising approach for integrating variable wind and solar power through the flexibility of hydro units and the storage capacity of reservoirs. These hybrid renewable energy systems, driven by climatological variables, are highly sensitive to climate change and may encounter periods of significantly reduced energy production. Such periods, termed "energy droughts," occur when energy generation falls below load demand or a prespecified threshold, posing critical challenges to system reliability and energy security. However, how energy droughts in HWSCSs will evolve under climate change and how to mitigate such events through strategic operations remain unexplored. Thus, this study proposes a generic framework for evaluating and mitigating energy droughts in HWSCSs under climate change. First, specific metrics for assessing energy droughts in HWSCSs are developed. Next, an adaptive operating rule for mitigating energy droughts is proposed and validated in both historical and projected future climate scenarios. A large-scale HWSCS in southwest China is selected as a case study. The results show robust improvements in reducing the frequency, duration, and severity of energy droughts across various climate scenarios. This study provides valuable insights for the sustainable management of HWSCSs in the face of climate change.