Security region of natural gas network in electricity-gas integrated energy system

•Concept and definition for SR of natural gas network in IES are proposed.•PSR and TSR of natural gas network in IES are defined.•A general OEF model is developed to construct the SR of natural gas network in IES.•The OEF model can form multi-dimensional SR with multiple security constraints. The strengthening interdependency between electricity network and natural gas network not only promotes the renewable energy integration and flexibility of electricity-gas integrated energy system (IES) operation, but also escalates the operation risk of the IES. Security region (SR) is a powerful tool to improve the situational awareness of IES security. However, the concept and application of SR for the natural gas network in IES is rare. This paper presents a SR of natural gas network in IES considering the influence of the electricity network and natural gas network. Firstly, the concepts of the SR, pressure security region (PSR) and transmission security region (TSR) of the natural gas network in the IES are defined by referring the definitions of electricity network SR. Then, the general nonlinear optimization energy flow (OEF) models are developed to form the SR, PSR and TSR of natural gas network in the IES, and the frameworks for constructing the SR of natural gas network in multi-dimensional space are also proposed. Results for the IES 30-20 and IES 118-3 × 20 test systems indicate that the proposal approach can construct the SR of natural gas network in IES with high accuracy.