The linearization method for transient gas flows in pipeline systems revisited: Capabilities and limitations of the modelling approach

Abstract

Supplying undisturbed energy is crucial to operators of gas networks especially when the network has different types of end-users with variable gas demands. Accurate modelling of transient gas networks as one of the large energy carriers is important in an integrated energy system. This study addresses a modelling approach of gas flows by revisiting the linearization method applied for solving governing equations of gas networks. The linearized model considers the main operational variables such as the pressure, mass flow rate, line-pack, density and compressibility. Dealing with the mass flow rate instead of the volumetric term in calculations allows integrating the gas motion equation more smoothly. Also it permits a trackable, quick, and an easy implementation of the calculations. The proposed modelling approach has been applied for a typical gas network and the operational variables have been followed up and compared to previous literature findings. The applicability of the model on analysing gas piping systems was proved and discussed. Quantitatively, a mean squared error less than 9e-4 is obtained comparing calculated pressure to a previous work based a linearization approach. The mean squared errors are generally less than 0.021 when comparing the present work to various other models from the published literature. Additionally, leakage, as one of the important concerns in gas operational management, was simulated to investigate the applicability of the proposed model on leak detection. It was found that the linearization model can inform about the occurrence of a leak in the gas network. Also, following the mass flow rate profiles, one can detect the leak and estimate its location. However, for a precise localisation of the leak position, through pressure signal profiles, a deeper analysis is required. The proposed linearization model is to be further adjusted to consider the wave aspect of pressure.