Operation of Natural Gas Pipeline Networks With Storage Under Transient Flow Conditions

TL;DR

This paper develops a nonlinear optimal control framework for natural gas pipeline networks with storage, incorporating detailed flow dynamics and reservoir models, to optimize economic profit and efficiency under transient conditions.

Contribution

It introduces a comprehensive reduced-order DAE model for pipeline and storage dynamics and applies a primal-dual interior point method for optimal control, validated through simulations.

Findings

Effective optimization of pipeline operations under transient flow conditions.

Validated methodology improves economic and operational efficiency.

Demonstrated applicability on multiple pipeline test networks.

Abstract

We formulate a nonlinear optimal control problem for intra-day operation of a natural gas pipeline network that includes storage reservoirs. The dynamics of compressible gas flow through pipes, compressors, reservoirs, and wells are considered. In particular, a reservoir is modeled as a rigid, hollow container that stores gas under isothermal conditions and uniform density, and a well is modeled as a vertical pipe. For each pipe, flow dynamics are described by a coupled partial differential equation (PDE) system in density and mass flux variables, with momentum dissipation modeled using the Darcy-Wiesbach friction approximation. Compressors are modeled as scaling up the pressure of gas between inlet and outlet. The governing equations for all network components are spatially discretized and assembled into a nonlinear differential-algebraic equation (DAE) system, which synthesizes above-ground pipeline and subsurface reservoir dynamics into a single reduced-order model. We seek to maximize an objective function that quantifies economic profit and network efficiency subject to the flow equations and inequalities that represent operating limitations. The problem is solved using a primal-dual interior point solver and the solutions are validated in computational experiments and simulations on several pipeline test networks to demonstrate the effectiveness of the proposed methodology.