Modeling the Integrated Natural Gas and Electricity Optimal Power Flow

This paper integrates the natural gas and electricity networks in terms of power and gas optimal dispatch. It shows the fundamentals of natural gas network modeling including pipelines and compression stations. It also describes the equality constraint that models the energy transformation between gas and electric networks. A mathematical model of this problem is formulated as an optimization problem where the objective function is to minimize the integrated gas-electricity system operation cost and the constraints are the power system and natural gas pipeline equations and capacities. Case studies are presented integrating the IEEE-14 test system and Belgian calorific gas network. The integrated electricity-gas optimal power flow problem is solved using an hybrid approach which combines evolutionary strategy algorithm with Newton's and Interior point method. It hybrid approach fully takes the advantages of both evolutionary strategy optimization and classical methods (such as Newton's and interior point method) which the former is able to jump out of the local optimal point and the latter boats the local exploration ability within the neighborhood of the optimal. It increases the precision and quickens the convergence. The proposed model shows the importance of the integration of the two systems in terms of operation, planning, security and reliability.