Study On The Gas Supply Reliability Of Natural Gas Pipeline Networks Based On Demand Side Analysis

Natural gas pipeline network system is a critical infrastructure connecting gas resource and market demand,and its reliable operation is directly related to the safe and stable supply of natural gas.In order to satisfy the market demands securely,it is necessary to study the reliability of the natural gas network system.Therefore,by means of analyzing the gas supply capacity and market demand and considering the transportion process of the natural gas pipeline network and uncertainties in the gas supply and market demand,the framework and methodology of gas supply reliability assessment for the natural gas pipeline network based on demand side analysis are developed in this dissertation.Firstly,the reliability of natural gas pipeline system is divided into three aspects,namely mechanical reliability,hydraulic reliability,and gas supply reliability.The definitions of the three types of reliability are clarified,and the corresponding reliability indicators are proposed.The research of the mechanical component in the natural gas pipeline network is the basis of the gas supply reliability assessment.With the intent of overcoming the deficiencies in the existing unit reliability evaluation model,this dissertation establishes and improves the reliability evaluation method of the natural gas pipeline,compressor unit,and underground gas storage.For example,a novel methodology is developed to update the reliability of the corroding natural gas pipeline by introducing the effect of failure data and corrective maintenance;the reliability evaluation model of the natural gas compressor unit under competing failure modes is established;and an integration method for assessing the operating reliability of the underground gas storage in a depleted reservoir,is proposed.The natural gas pipeline system is the most important component of the natural gas pipeline network system.The research idea of the gas supply reliability for the natural gas pipeline system is the same as that for the natural gas pipeline network system.Therefore,the methodology for assessing gas supply reliability of the natural gas pipeline system is developed firstly in this dissertation.The evaluation methodology is divided into two situtions depending on whether the underground gas storage is considered or not.When ignoring the underground gas storage,the methodology consists of a gas supply capacity calculation method of the natural gas transmission pipeline system and a market demand prediction model based on demand side analysis.In the calculation process of the gas supply capacity,the research results of the unit reliability are used,the uncertainty of the system’s operating state is considered,the topology analysis and transportation process of the transmission pipeline system are combined,and the dyanamic of the system with large time delay and nonlinearity is introduced.In terms of the market demand,based on the demand side analysis of the targeted market,the demand of natural gas is predicted,and the uncertainty of the market demand is taken into account.Combining the calculation results of the gas supply capacity and market demand,the gas supply reliability is evaluated using the proposed gas supply reliability index.Based on the above research results,by analyzing the role of the underground gas storage in seasonal peak shaving and emergency gas source,and considering the uncertainties in its gas injection/production capacity,the methodology for assessing the gas supply reliability of the natural gas pipeline system is developed which coupling the transmission pipeline system and underground gas storage system.Finally,based on the research results of the reliability index,unit reliability,and the demand side analysis,the research idea of the gas supply reliability of the natural gas pipeline system is applied to the research of gas supply reliability of the natural gas pipeline network,and the calculation methodology of the gas supply reliability for the natural gas pipeline network system is explored.In the methodology,the Monte Carlo approach is used to simulate system’s state transition process,and maximum flow algorithm combined with hydraulic-thermal analysis of natural gas pipeline network is employed to calculate the gas supply.The demand of the targeted market is then predicted,and the market demand uncertainty is considered in the predicting process.The gas supply reliability is then assessed by comparing the gas supply and market demand.