Improvement of renewable energy accommodation and energy utilization efficiency are both promising channels for sustainable development of electric and thermal energy systems. In view of the difference in the study subject and the analytic method

the constitutive relation between the basic components in the thermal system is revealed from the perspective of heat transport. By introducing the entransy theory and analogy between electricity and heat in transmission

an alternative model is developed from the angle of energy flow by considering the driving force and thermal resistance in heat transfer. Together with the topological structure

the energy flow model of the thermal system is developed to describe the law of integral heat transport. On this basis

the energy flow model of the electric-thermal integrated energy system in consideration of energy conservation and heat transfer irreversibility at the same time. This will unify the study perspective of electric and thermal energy in transmission while laying bare the law of integral energy transport. Finally

a simple integrated energy system is employed to minimize the total coal consumption by using the energy flow method and the dual-boundary method

respectively. The results show that the predicted wind power generation with the energy flow method is more accurate

which shows the feasibility and necessity.