Optimal Planning of Energy Hub for Joint Operation of Electricity and Gas Systems Considering Reliability Index

By the recent growing of global trend for decentralized power generation via natural gas, the interest in joint operation of several energy carriers has substantially increased. The most significant concept in this regard is the “Energy Hub”, which in this paper is employed to supply electrical and heat demands via electricity and natural gas carriers. Transformers, furnaces, combined heat and power (CHP) units, and electrical and heat storage units are utilized for this purpose. Unconventionally, CHP units are not modeled as constant electrical and heat efficiencies, and thorough operational characteristics of these units are employed in the problem formulation, which consists of feasible operating region (FOR), and nonlinear input-output relationship. In order to formulate the problem as mixed-integer linear programming, a piecewise linear approximation of CHP units’ operating region is presented to linearize their nonlinear operation. Additionally, the reliability index is added to the problem formulation, containing a model for changing the output point of CHP units in contingencies. The problem is aimed at choosing the best combination of candidate devices for decreasing total costs and increasing the reliability of supply in a long-term planning period. Simulations are presented for a case study, investigating impacts of applying energy price uncertainty on the results.