Reliability Analysis Of Gas Supply In Gas Pipeline Network In Northern Sichuan And Chongqing

North Gas Pipeline Networks in Sichuan and Chongqing take charge of transmitting gas across the east and west of Networks in Sichuan and Chongqing with 1500 kilometers pipelines and a few of supplies and natural gas stations which make the management of the whole network difficult for administrators and lack of systematical and comprehensive acquaintance. Through the analysis of various running states of networks, carrying out the gas supply reliability analysis will provide scientific and reasonable basis for determining the network weak link and main factors influencing gas supply reliability, and to provide theoretical basis to make supply plan effectively.The main research content and results are as follows:(1) By collecting operational data and maintenance records, pipeline failures are identified as the main failure types for North Gas Pipeline Networks. Maximum Likelihood Estimate is used to calculate the mean failure rate ? and mean time to repair MTTR,.with Kolmogorov-Smirnov method is verified in the significant level of 0.05, pipeline failure rate follows poisson distribution with parameters ?=0.0012times/(a-km), and time to repair TTR follows exponential distribution with parameters MTTR=38.9h.(2) The network system can be simplified as a network topologic structure with 42 nodes and 38 pipelines by graph theory under the normal operation of North Gas Pipeline Networks, then based on valve shutoff in fault of pipeline, reconstruct the corresponding fault network topology structure by using correlation matrix reconstruction.(3) Based on the non isothermal, unsteady characteristics and the thermodynamics characteristics of gas flowing in the pipe, establish the dynamic hydraulic analysis model of North Gas Pipeline Networks in Sichuan and Chongqing by using TGNET to analyze hydrodynamic calculations of network under different conditions of gas supply. Considering the changing gas demand of the nodes will influence the actual volume of the nodes, take the moment when the actual volume of the nodes are most heavily impacted as the starting moment of pipeline fault. Based on gas demand and Supply between nodes and supplies, Search method can be used to determine the gas supply paths.(4) Classify the running states of North Gas Pipeline Networks into " I ", "II", "III" by analyzing dynamic hydraulic simulation results of gas network system and the changes of gas supply path, then use markov process, combined with maintenance rates, pipeline failure rate and hydraulic credibility of nodes and system, establish supply reliability calculation model of North Gas Pipeline Networks in Sichuan Rs and Chongqing and the nodes Ri.(5) Calculate the supply reliability of nodes and network system under two gas supply conditions where network system respectively has 11 supplies in use or 6 supplies in use. There are 7 key fault pipilines under the former gas supply condition, and they are e3, e4, e17, e18, e,9,e37 and e38,the weaknesses are node 3, node 4, node 31. There are 11 key fault pipilines under the latter gas supply condition, and they are e,, e2, e3,e4, e17, e18, e19, e35, e36, e37 and e38, the weaknesses are node 1, node 2, node 3, node 4, node 31.(6) Under the same gas supply condition, increase 1-5 times of mean time to repair MTTR and pipiline fault rate ?j to respectively calculate the gas supply reliability of every nodes and network system, then analyze the impact of MTTR and ?j, MTTR have greater impact on the gas supply reliability of nodes and supplies than ?iThe results will provide a hand for pipeline management personnel to prevent the intrusion and damage to pipeline network, also gives some planning and construction, which has great practical significance.