Entropy state calculation model for integrated energy systems

The integration of renewable energy sources and multi-energy networks in integrated energy systems (IES) introduces significant challenges related to energy degradation, driven by exergy losses during energy conversion/transmission and uncertainty-induced usability reduction. To address these issues, this study proposes a novel entropy state calculation model and analytical framework for assessing energy quality degradation within IES. By unifying thermodynamic entropy (quantifying physical exergy loss) and information entropy (capturing uncertainty-driven energy mismatch), the model integrates physical and information systems into a cohesive entropy state framework. The methodology is validated through a case study on a real-world IES in Tianjin, China (TJBC), demonstrating its capability to reveal entropy state distributions across subsystems under varying network structures and operational modes. Results highlight the dominance of energy conversion processes (e.g., combined heat and power units) in system-wide entropy increase and the critical role of renewable uncertainty in local energy quality degradation. The proposed framework provides a unified metric for optimizing energy efficiency, guiding infrastructure planning, and mitigating energy degradation in high-renewable-penetration IES, contributing to sustainable and high-quality energy system development.