Long-term optimization operation of hydro-photovoltaic hybrid system considering short-term energy curtailment losses caused by transmission channel capacity limitation

Hydropower and photovoltaic (PV) systems, as dominant renewable energy sources, offer strong synergistic potential through coordinated operation. Although hydro-PV hybrid systems can leverage cascade reservoirs and regional solar resources to improve energy utilization efficiency, existing long-term optimization models largely overlook the multi-timescale information coordination within a single modeling hierarchy. This critical gap fundamentally limits their practical effectiveness in guiding real-world system operation. To address this issue, the study develops a novel energy loss function that incorporates the transmission capacity constraints, derived through multi-scenario simulations. Subsequently, a new hydro-PV hybrid system multi-timescale optimization operation model coupling is constructed by integrating the energy loss function. The proposed model is applied to a real-world hydro-PV hybrid system located in the Beipan River basin of Guizhou Province, China. The results demonstrate that the energy loss function effectively evaluate long-term PV curtailment risks associated with hydropower output. Furthermore, the study found that proposed model enhances coordination between hydropower and PV generation, thereby maximizing overall power generation efficiency. Specifically, it reduces the PV curtailment rate by 5.21 % under hydro-PV independent operation and by 10.19 % under hydro-PV joint operation compared to conventional models. This study offers valuable insights for optimization modeling of hydropower-dominated hybrid systems and provides practical strategies to improve the utilization efficient of renewable energy resources.