Key technologies and developments of multi-energy system: Three-layer framework, modelling and optimisation.

The energy crisis and environmental pollution are the most serious threats to human survival. Currently, many countries and regions have set the goal of carbon neutrality by 2030–2060. Multi-energy systems (MESs), which integrate different energy systems such as electricity, natural gas and district heating networks, have received significant support and development to expedite this process. However, due to the complexity of its structure, the consideration of such a concept necessitates an appropriate model to describe the planning and optimal energy flow throughout the system. Another critical direction for future MES development is the rapid and accurate calculation of MES models. Numerous research institutions and large corporations have concentrated their efforts in this area, which has resulted in the publication of thousands of papers. This article aims to provide readers with a comprehensive and critical overview of the typical MES model and its associated optimisation algorithms to assist them in identifying appropriate models and associated solution methods for their research or engineering problems. We summarise the concept and potential three-layer structure of MESs and introduce their fundamental components in depth. Subsequently, according to different research or application objectives, we divide MES models into three categories and discuss their application scenarios, modelling methods and solution techniques. Additionally, we report six significant obstacles encountered in current real-world MES projects based on our practical engineering experience and propose seven potential development directions for future optimisation of the operating technology. • Providing readers with an overview of the MES model and related algorithms. • Summarizing the concept and potential three-layer structure of MESs. • Dividing MES models into three categories, discussing their modelling and solving. • Reporting six significant obstacles encountered in current MES projects. • Proposing seven potential development directions for future technology. [ABSTRACT FROM AUTHOR]