Introduction: Dynamic operation of the National Transmission System (NTS), where users are starting up (ramp-up), shutting down, and/or changing flow rates quickly, can produce challenging scenarios on the gas transmission network. At a wider network level, the manifestation of this behavior is a quick changing flow pattern which calls for a rapid reconfiguration of the system. Where as on a local subsystem the result can be fast transient effects which may have an adverse impact on the compressors and other equipment which momentarily impose high stresses on pipe walls and high velocities, among other issues. This collaboration research project with the University of Manchester has been established to investigate novel methods used to determine a new, more accurate ramp rate model.

Objectives:

This project aims to create comprehensive fast transient models (using computational fluid dynamics (CFD) methods) of National Transmission System (NTS) components to enable a fuller understanding of the expected impact of quick flow changes on the system. This will also facilitate validation of the default 50 MW/minute ramp rate.

Expected Benefits:

• Publication of a technical paper / thesis on the work with discussions on the findings, recommendations and suggestions for further work.

• Production of detailed models of local NTS components.

• Proposal of a new default ramp rate or provision of analysis data to justify the existing value.

• Integration of existing network modeling software with CFD models.