A Fully Linear-Constrained Optimal Electricity-Gas Flow in an Integrated Energy System

The wide application of gas-fired units has enhanced the interdependency between electrical power system and natural gas system and raised the necessity on coordinated analysis on integrated energy systems. This paper focuses on the optimal electricity-gas flow (OEGF) analysis of an integrated electricity and natural gas system (IEGS) and proposes a linearized OEGF model considering electricity transmission losses (ETL). The modified direct current (DC) power flow model embedded ETL and a steady-state gas flow formulation are adopted to describe the IEGS. The ETL is modeled by a quadratic function of electrical phase angles. To address the nonlinear ETL model and nonconvex gas flow equations, the Taylor expansion is employed for linearization to reduce the computation burden. To obtain the high-quality initial points for Taylor expansion and then guarantee the accuracy of linearization, a two-stage linearized method is further developed to solve the proposed OEGF model. Numerical results on an IEGS with the IEEE 14-bus system and a 12-nodel gas system demonstrate the effectiveness of proposed OEGF method.