Optimal Expansion Planning of Multi-energy Generations and Natural Gas Storages in Integrated Energy System

Regional electrical distribution network, natural gas network and heat network are interconnected closely with the combined heat and power (CHP) and electrical boiler (EB) to form the integrated energy system (IES). The distributed natural gas storages belonging to system are supposed to smooth the gas demand curve and decrease operation cost. In this paper, an optimal expansion planning model for multi-energy generations and natural gas storages in IES is proposed. Since the multiple energy flow (MEF) constraints are highly nonlinear and nonconvex, some piecewise linear approximations are adopted to manage the nonlinearity of MEF constraints to reformulate the mixed integer linear programming (MILP) model. The planning model would optimally determine appropriate investment candidates for CHPs, EBs and natural gas storages. A modified integrated energy system case is evaluated by simulating operation of typical day in winter and summer to demonstrate the effectiveness of the proposed planning method.