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This paper describes the essential features and experience of applying a fluid transient model to the operation support system of large city gas pipeline networks. The system, operating in the second largest city, Osaka, in Japan since 1992, includes the functions of a real-time leak detection and localization, a fast predictive computation of the pressure and flow distributions in networks, and an interactive training simulator using a transient model connected with SCADA training system. To achieve fast forecasting calculation in real-time manner, the combined method of a fully implicit transient calculation for high pressure transmission networks and a steady-state calculation for middle pressure distribution networks is developed. The actual performance of real-time leak detection and the accuracy of the forecasting model are discussed.

This paper describes a method for estimating the position of a detected leak by applying a fluid transient model to a real-time pipeline system. The method takes into account flow rate and pressure profiles along a pipeline in a transient condition based on an assumption of quasi-steady-state flow. The result of case studies using a hypothetical gas pipeline system shows that, even in a transient condition, the method gives a more accurate estimation of a leak position than conventional methods which do not consider flow rate or pressure profiles along a pipeline. The method is also applicable to a pipeline having consumer stations which cause abrupt changes of flow rate profile along the pipeline. Furthermore, the influence of instrument accuracy on the result of the method is examined. The result also shows the advantage of the method compared to the conventional methods.

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