Steady-State Calculation Method and Model for Energy and Carbon Flows in Electric-Gas-Heat Integrated Energy System

In multi-energy systems, the conversion of energy between different forms couples the flow of carbon emissions between various energy systems. As a result, the analysis of carbon emissions in multi-energy systems is more complex than that in the individual energy systems. It is urgent to track the carbon emission flux (or carbon flow) of hybrid energy networks and clarify the carbon discharge responsibilities of different participants in the networks. In this paper, the analytical model for steady-state energy flow within the gas and heat grids of hybrid systems are clarified and a detailed introduction is given to describe the carbon flow calculation method of the electricity-gas-heat networks, and based on above, an energy carbon flow model of multi energy systems was completed and applied to establish calculation examples for the power grid and gas grid, thereby illustrating the relationship between energy flow and carbon flow. The results shows that the power system injected carbon flow rate is equivalent to the aggregate of the system's outflow carbon flow rates, explaining that the carbon emission flow calculated based on the balanced power flow is automatically balanced. And for the gas system, there is a direct correlation between natural gas pipeline carbon emissions and gas flow rate. The method in this paper provides a foundation for the joint analysis of energy-carbon flows in integrated energy systems.