1.College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, China;2.Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education (Shandong University), Jinan 250061, China

The integrated energy system (IES) of electricity-gas-heat interconnection presents the characteristics of multiple time scales in the process of energy transmission, and the dynamic characteristics of the gas-heat network contain abundant flexible capacity. Fully tapping the potential flexibility of IES can effectively improve the consumption level of renewable energy. Thereby, an optimal dispatching model of IES considering the flexibility of sub-hourly-time-scale operation is proposed. Based on the analysis of the system operation regularity in the net load variation interval, the mathematical expression of power system flexibility demand and resources is derived. Then, the dynamic characteristics of gas network and heat network are analyzed, and the mathematical models of gas network and heat network which provide operation flexibility are established, respectively. Based on this, an optimal dispatching model of IES considering the flexibility constraints of sub-hourly-time-scale operation is constructed, and the nonlinear constraints in the model are linearized. Finally, the case studies on the modified electricity-gas-heat 24-20-16 bus system demonstrate that the dynamic characteristics of the gas-heat network can enhance the system flexibility in a short time scale and significantly improve the economy of system operation.