The Optimal Design Of Urban Gas By Genetic Algorithm

Gas pipeline network system (simlely named gas network system) is the main way to transmit gas in the worid. It includes long-distance gas transmission pipeline system and urban gas network system. Up to now, long-distance ramate gas transmission pipeline system is mainly the object in optimization design. Comparatively, study on urban gas network optimization is fewer and not indepth. While as one of the important basic establishments, gas network system is becoming huger and more complex with the expansion of city scale and the sharp increase of gas demand. Whether the nerwork design is scientific and economical will direactly affect total investment and reliability of gas network system. Besides, some new technologies used for nerwork control also require an optimal urban gas network system. Therefore, it is quite essential to apply advanced optimization technology in obtaining optimal design of gas network.After comparing conventional design methods of gas network, basing on the previous optimization techniques, together with the characters of urban gas network, the optimal model of urban nature gas network is established by setting up the objective function namely the minimum cost of construction and operation of the network, and the restrictions in terms of the steady state network,the flux and press of each node and the drop of lines. On the basis of existing theory and production, simple genetic algorithm is modified. New appropriate genetic operators and evolutionary strategies are designed and genetic parameters selection is studied through computer simulation tests in a small network, thus global optimal solution to gas network parameter optimization model can be obtained.By an actual gas network project of a middle-sized city, the optimization model with reliability constraint and optimization arithmetic can acquire satisfied solutions to rngineering peoject and have certain references value for diameter optimization design of urban gas network.