Optimal dispatch of large multi-carrier energy networks considering energy conversion functions

An integrated coordination of multi-carrier energy networks including gas, heating, cooling and electricity can increase the flexibility, efficiency and sustainability of energy systems. The optimal dispatch of such systems is complicated by the non-convex nature of their energy conversion processes. Although these processes can be represented in mixed-integer linear programmes, real-time constraints of an online dispatcher may not be satisfied. In this paper, two approaches for alleviating this problem are developed and compared: one is based on a relaxed mixed-integer linear formulation and the other on mathematical optimization with complementarity constraints. Simulation results on realistic systems demonstrate that both approaches solve large multi-carrier dispatch problems efficiently. The mathematical optimization with complementarity constraints is computationally less intensive but the relaxed mixed-integer linear formulation is numerically more robust.