Standardised modelling and optimisation of a system of interconnected energy hubs considering multiple energies—Electricity, gas, heating, and cooling

Abstract

The system of interconnected energy hubs (EHs) is a key multi-carrier energy system (MES) model. It is difficult, however, to directly calculate the operational state of the model because of its highly dimensional nonlinear characteristics. To resolve the foregoing problem, a standardised modelling and optimisation method for the system of interconnected EH model is introduced in this paper. In this proposed method, one-dimensional and multi-dimensional piecewise linear approximation methods are adopted to simplify non-convex natural gas transmission functions, generator cost functions, and compressor function. Moreover, a multi-step linearisation method is applied to EHs. The whole system can accordingly be reformulated as a mixed-integer linear programming (MILP) problem. In contrast to the traditional model, the formulated MILP model is effortlessly implemented in the optimisation of the MES with existing advanced optimisation techniques. Finally, the method is verified using a modified three-hub interconnected system. The test results show that the method can save more than 90% computational time with sufficient accuracy. The results also demonstrate that the unified dispatch exploits different energy resources, and the applied energy storage devices can reduce the operational cost from $319,840.267 to $316,382.685.