Flexibility evaluation of active distribution networks considering probabilistic characteristics of uncertain variables

The flexibility evaluation of distribution networks has attracted significant research attention with the increasing penetration of renewable energy. One particular gap in existing studies is that little attention has been paid to the probabilistic characteristics of uncertain regions. In this study, a novel sequential flexibility evaluation method is proposed based on the feasibility analysis of the uncertain region of photovoltaic active power and load demand. The model features the uncertain region with probabilistic characteristics, which is essential for analysing the impact of probabilistic characteristics of uncertain variables (PCUVs) on flexibility evaluation. The sequential direction matrix is adopted to reflect the major factor of flexibility shortage. The evaluation procedure is modelled as a bi‐level optimisation problem. Demonstrated by the simulation results, the flexibility index is larger by considering the PCUV. Furthermore, the elements in the sequential direction matrix indicate that the photovoltaic power during midday is the major cause of flexibility shortage.