Research On Gas Network Fault Diagnosis

With the national energy structure adjustment, a number of key state construction projects including transporting natural gas from west to east, transporting the natural gas from Sichuan to east and importing LNG gas and so on, indicate that China has entered into the gas universal application and rapid development period. City gas also is booming and becomes an infrastructure of the urban energy configuration, and an essential lifeline for the city works. With the increasing popularity of city gas, gas accidents are also increasing. Gas network in case of failure will affect the daily lives of residents, the normal production of industry, furthermore,a major gas breakdown cause great loss of life and property. Therefore it is necessary to research on gas network fault diagnosis.This paper carrys out the fault diagnosis technology reseach focusing on the gas admixture plug, the water plug, the icejam and so on.The main researched content contains the following several aspects:Firstly, this paper analyzes the various reasons of formating gas network congestion and the way treatment of various types of plug failures, analyzes the various of changing parameters of gas pipe network, which caused by the plug failure, establishs gas network fault diagnosis mathematical model, including the objective function, various types constraints,determines evaluation criteria of pipe network fault level.Secondly, this paper analyzes the effects that using influencial coefficients expressing changed pipe and diameter to the node pressures and the pipe flow changes, and uses the combined influence factors of the pipe on the node pressures and the pipe flow to determine the entire pipe network influenced the pipeline, these pipe sections as fault diagnosis pipe, uses impact factor, according to the given monitoring standards,to determine the pressure measurement point and the flow measurement point.Thirdly, this paper introduces the theory of the generalized reduced gradient method and the genetic algorithm; analyzes using generalized reduced gradient method for solving fault diagnosis model of the process and the mathematical formula and determine the algorithm steps; analyzes how to use genetic algorithm to solve the fault diagnosis model process and calculate steps.Fourthly, based on the characteristic of local search capability of the generalized reduced gradient is strong, computing speed is quick and the global search ability of genetic algorithm is strong, Setting a new hybrid algorithm.It has the features of high speed and high precision. This paper propose the basic thinking of the hybrid algorithm of, design hybrid computational steps, and compile the programs with Visua C++.This paper uses the written procedures to carry on fault diagnosis for the low pressure, medium pressure gas network.The results show that the error is not exceeding 6%, the hybrid algorithm is feasible and it can meet the engineering needs. Meanwhile,comparing the node pressure,pipe flow and equivalent diameter which are calculated with the design condition of the node pressure, pipe flow, pipe diameter and combined with the pipe blockage rate, we can determine the fault existence of diagnostic pipeline or not, if location of the fault pipe and the level of fzulty are determined,it's convenient for us to take measures.