To address the retrofitting and upgrading needs of existing combined cooling

heating and power multi-energy systems (CCHP-MES) and meet the modular construction requirements of future CCHP-MES

this paper proposes an innovative expansion configuration optimisation method for CCHP-MES considering tracking ability improvement based on scheduling degree of freedom. Firstly

according to the directed graph theory

a scheduling degree of freedom (SDOF) determination method is defined to verify the structural reasonableness of CCHP-MES and assist in expansion equipment selection. For two types of operational scenarios—load demand expansion and load demand type expansion—the tracking-economy multi-objective expansion configuration optimisation models considering SDOF are constructed

and different expansion schemes are evaluated based on comprehensive evaluation of system tracking

economy and environment. The efficacy of the planning model is verified using typical load demand and renewable energy data in Nanjing as an example. The results show that the proposed building block expansion method can achieve better tracking performance improvement with relatively small economic loss and also enhance the renewable energy share in total energy consumption of CCHP-MES to achieve the ultimate carbon neutrality goal.