Abstract: To address the issue that current regulation potential evaluation methods for flexibility resources fail to consider the optimal operation status of distribution transformer zones, resulting in adverse impacts on the zones' autonomous operation when supporting the upper-level grid's power regulation, this paper proposes a modeling method for regulation potential range that incorporates autonomous operation optimization of distribution transformer zones and source-load uncertainties. Firstly, the scattered flexibility resources within the distribution transformer zone are aggregated, and a regulation model is established. Then, the interaction power baseline between distribution transformer zones and the upper-level grid is optimized to achieve the optimal operation of the distribution zone. Finally, accounting for source-load uncertainties and based on baseline interactive power, a transformer zone regulation potential range model is developed to enhance the upward/downward regulation margins, with solution via the jellyfish search algorithm. Simulation results demonstrate that the proposed method can accurately evaluate the regulation potential range of the transformer zones, providing reliable references for the upper-level grid to allocate regulation tasks effectively, and achieve a balance between optimal operation and regulation capability of the transformer zones.