Part-load operation risk assessment of hydropower units in hydro–wind–solar​ hybrid system considering hydraulic characteristics

Establishing hydro–wind–solar hybrid system (HWSHS) is essential to combat the fluctuant and uncertain variable renewable energy (VRE). In HWSHS, the main function of hydropower is gradually changing from electricity generation to equal emphasis on electricity generation and regulation. This means that hydro units are sometimes forced to operate in part-load regions to regulate and avoid power shortage. However, hydropower units operating in the part-load regions exist potential safety risks owing to the hydraulic characteristics (e.g., vibration and pressure fluctuation et al.). Here, an economic operation model of HWSHS considering precise head loss and shared pipeline is proposed. Then, a risk assessment framework of hydro units in HWSHS operating in the part-load regions is presented. Meanwhile, the uncertainty of VRE is also considered. Finally, the model and framework are applied to a case in the Jinsha River basin of China. The results show that (1) the risk framework could be assessed the safety risk of hydropower units for different scenarios during a period and even be applied to future risk forecasts. For example, the risk of hydropower units on May 3, 2019 is lower than the other two days; (2) the risk of hydropower units from May 1, 2019 to May 3, 2019 averagely increases to 3.693 h (duration), 15.389% (probability) and 63.721 MW (mileage) compared with the scenario without VRE; and (3) the main factors of hydropower units being forced to operate in part-load regions are the high proportion and the uncertainty of VRE. Thus, the study supplies support for assessing the risk of hydropower units in HWSHS to regulate VRE.