The work region and total work capability of integrated energy system: Concepts, models, and mechanisms

Exergy is the quantification of the work capability of energy. Accurately characterizing the limits and scope of the work potential within an integrated energy system (IES) is a crucial foundation for achieving energy-quality matching, hierarchical utilization, and enhancing the level of energy utilization. Based on the “region” method, this paper first establishes a work region model for the IES. It demonstrates a linear mapping relationship between the operating point of the work region and that of the operation region, and proves the isometric, similarity, and nonlinear geometric transformation relationships between the work region and the operation region in a multi-dimensional space. Furthermore, an improved dichotomy method is proposed as a solution for determining the security boundary of the work region, balancing both computational accuracy and efficiency. Subsequently, a model for the maximum total work capability (TWC) and the TWC curve of the IES is established. Based on the mathematical relationship between TWC and total supply capability (TSC), three methods for calculating the maximum TWC are proposed. Finally, through three typical case studies, the operation region and TSC were used as comparison benchmarks to validate the accuracy and superiority of the proposed model and method, revealing the phenomenon of local work capability decay under different operating conditions. The research presented in this paper contributes to the collaborative development of energy quantity and quality in IES, providing essential theoretical and technical support for the planning, operation, and energy market transactions of IES.