A state space model for transient flow simulation in natural gas pipelines

A transient flow simulation for gas pipelines and networks is proposed. The proposed transient flow simulation is based on the state space equations. These equations are derived by the transfer function equations. However, the transfer function model cannot be used for a complicated network. One can easily apply a state space model for a large and complicated network. For a state space model, the equivalent transfer functions of the nonlinear governing equations are derived for different boundary condition types. Next, the state space equations are derived from the transfer functions. To verify the accuracy of the proposed simulation, the results obtained are compared with those of the conventional finite difference schemes (such as total variation diminishing algorithms, method of lines, and other finite difference implicit and explicit schemes). The effect of the flow inertia is incorporated in this simulation. The accuracy and computational efficiency of the proposed method are discussed for a single gas pipeline and a sample gas network; besides for accuracy of this method for different boundary conditions, results for a sample gas pipeline with different boundary conditions are compared.