Abstract: The increasing penetration of natural gas power generation and ever-developing power to gas （P2G） technology in recent years have promoted the coupling between the power system and the natural gas system than ever before. This coupling has introduced new challenges to the planning of integrated electricity and natural gas energy systems, as the existing power system planning models normally overlook the impacts of natural gas or other energy systems. Given this background, this paper studies the collaborative planning of integrated energy systems with combined heat and power （CHP） plants and P2G stations. First, the energy center concept is introduced and modeled, and in an energy center various kinds of energy conversion such as CHP can be carried out. A nonlinear model for an integrated energy system with multiple interconnected energy centers and P2G stations is next presented and linearized. Then, this paper takes the minimum overall cost as planning objectives including investment cost, operation cost and energy shortage cost characterizing the reliability of integrated energy systems, optimizes the location sizing problems of traditional generating units, CHP plants, P2G stations, gas-fired boilers, transmission lines and natural gas pipelines with using general algebraic modeling system（GAMS） -based CPLEX solver, and evaluates the reliability of the planning scheme and the benefit generated by P2G stations in promoting the capability of accommodating intermittent renewable energy. Finally, the effectiveness of the proposed collaborative planning model is demonstrated by a sample integrated energy system.

Key words: integrated energy systems, collaborative planning, energy center, combined heat and power （CHP）, power to gas （P2G）