Enhancing accuracy of flexibility characterization in integrated energy system design: A variable temporal resolution optimization method

Integrated energy systems offer substantial potential for enhancing renewable energy integration. However, due to the distinct dynamic characteristics between system components, the characterization of system flexibility in integrated energy systems remains a challenge. This further complicates their optimal design, as underestimation or overestimation of flexibility during design can result in unexpected operational performance degradation. This article aims to improve the accuracy of system flexibility characterization in the optimal design of an integrated energy system, and address the conflict between high-precision modeling requirements and the difficulty of solving high-dimensional optimization problems. Specifically, higher temporal resolution operational constraints are adopted to characterize system flexibility, and a variable temporal resolution optimization method is developed, which could effectively reduce computational burden whilst maintaining accuracy. Optimization results demonstrate a significant reduction in solving time, approximately 98.5 %, compared to directly shortening the time step. Moreover, the proposed method ensures optimal results with a reliable system configuration, preventing load loss during operation. Additionally, it significantly reduces total ramping amount and adjustment times of coal-fired units by over 56.0 % and 32.3 % respectively, while achieving a 0.9 % reduction in carbon emissions. Despite these benefits, the total annual costs of the system only experience a minimal increase of 0.6 %.