Dispatch And Operational Risk Evaluation For Integrated Electricity And Gas Systems Considering Demand Response And Network Topology Optimization

With energy shortage and environmental pollution increasingly serious,the modern energy system has been developing from the independent operation mode of electricity,gas and heat systems to the coordinated operation of integrated energy systems.The integrated energy system(IES)is an important carrier of future energy system.The integrated electricity and gas system(IEGS)is a typical form of integrated energy systems.On the one hand,IEGS can realize multi energy complementary and improve energy efficiency.On the other hand,IEGS also brings challenges to the safe operation of the system.Dispatch and risk evaluation of IEGS are important research contents of IES.In recent years,a large number of research achievements have been obtained.However,the existing dispatch method of IEGS still has the shortcomings of insufficient utilization of demand response resources and not considering the network topology optimization;Besides,the risk evaluation is mainly based on the long-term risk evaluation,which is difficult to quantitatively evaluate the short-term operational risk of IEGS.In view of the above problems,considering network topology optimization and integrated demand response,the dispatch and operation risk evaluation have been studied in the thesis.The main work and achievements are as follows:(1)A day ahead dispatch model considering network topology optimization and integrated demand response is proposed.Considering four demand response strategies of load reduction,transfer,translation and substitution,a flexible load scheduling model in IEGS is established.Aiming at the translatable load,which is rarely involved in the existing research,a translatable load model considering the constraints of translation period,times and amount is proposed.On this basis,integrated demand response and network topology optimization are introduced into the day ahead dispatch of IEGS and the "source-grid-load" coordinated electricity and gas dispatch model is proposed.The effectiveness of the proposed model is verified by an IEGS example.The results show that the proposed model can effectively promote wind power consumption and reduce the operation cost of IEGS.(2)A dynamic energy flow model and a real-time operation risk evaluation method are proposed.Considering the frequency regulation of power system,the characteristics of multi balance nodes of natural gas network and the dynamic characteristics of gas flow,a dynamic energy flow model of IEGS is proposed;On this basis,with the random variation of electricity/gas load and wind power considered,the real-time risk evaluation indices and probability evaluation method of IEGS are proposed.The effectiveness of the proposed dynamic energy flow model and the real-time operation risk evaluation method is verified by an IEGS example.The results show that the dynamic characteristics of the gas flow have a significant stabilizing effect on the state change of IEGS,and it is necessary to consider the multi balance nodes and the dynamic characteristics of gas flow in the real-time risk evaluation of IEGS.(3)An operational risk evaluation method for IEGS considering demand response and network topology optimization is proposed.Based on the concept of virtual gas storage,a pipeline fault model is proposed to describe the segmented isolation and storage effect of natural gas pipeline.Considering the random variation of wind power and load and the random failure of components,a series of probability evaluation index is proposed to describe the load shedding risk of IEGS.Considering network topology optimization,the optimal load shedding model of IEGS is proposed,and finally the operational risk evaluation method of IEGS considering demand response and network topology optimization is formed.The effectiveness of the proposed operational risk evaluation method is verified by an IEGS example.The results show that the proposed method can effectively evaluate the short-term operational risk of IEGS and reflect the high-risk period and area of the system.Both demand response and network topology optimization are conducive to reduce the operational risk of the system.