Operational decision of wind–photovoltaic–energy storage integrated system in day-ahead and ancillary service joint market considering weather variability

The wind–photovoltaic–energy storage integrated system (WPESIS) is an efficient way to consume large-scale and high-proportion wind and photovoltaic power. Its unique system structure enables it to participate in the electricity market and provide ancillary services. Compared with traditional power sources such as coal-fired units, the operational effect of WPESIS is easily affected by weather variations. Thus, this research presents an operational decision model for WPESIS in day-ahead and ancillary service joint market (DAASJM) that considers weather variability. First, a weather–power dual-threshold collaborative classification method is constructed to divide time intervals into deterministic and uncertain periods. The uncertain time intervals are divided into five types of weather–price coupling scenarios based on the fluctuation pattern of market price. Second, the weather transmission risk dimension is introduced into the traditional risk–return framework to quantify the opportunity loss risk arising from weather variability. Using this method, the framework is improved to adapt to the above uncertain scenarios. Third, a DAASJM operational decision-making model considering weather variability is established based on the improved risk–return framework, and a mixed-integer quadratic programming method is used to solve the model. Multidimensional case validation results show that operational decisions considering weather variability achieve a 2.91% increase in revenue compared with the traditional model. Compared with participating solely in the day-ahead electricity market, participating in DAASJM resulted in a 6.28% increase in revenue. Additionally, sensitivity analysis of operational results indicated the model's adaptability to risk changes.