ABSTRACT

An advanced gas management system requires a good estimate of the operating conditions of the gas pipeline. These conditions can be obtained with a Real-Time Transient Model (RlTM) driven by telemeter4 measurements of pressure, temperature and flow. Telemetered measurements are not made primarily for this purpose and therefore are not optimized in their number, scan rate, performance or geographical position to drive a R"h4. NOVA has tested the practical installation of a RT"M on a simple subnetwork of its pipeline system. This installation uses the existing Supervisory Control and Data Acquisition (SCADA) system (no measurement points were added). In this paper we describe the practical problems that limit the performance that can be expected and the impact such a R?TM has on the adual management of the line.

INTRODUCTION

The Gas Transmission Division of NOVA Corporation of Alberta operates ii large gas transmission pipeline in the Province of Alberta, Canada. The system consists of over 14 170 km (8,805 miles) of pipeline, ranging in size from 60.3 to 1066.8 mm (nominal pipe size of 2 to 42 inches), and 36 compressor stations with over 400,000 kW (500,000 HP) installed power. There are over 825 mapr receipt and delivery points. More than 60% of Canada's gas production is transported through NOVA'S facilities. Since the NOVA system is long, heavily networked (960 pipeline segments) and has a very large number of receipt and delivery points, with respect to modelling it cannot be classified strictly as a transmission line nor as a collection/distribution system. A map of the NOVA system is shown as Figure 1. When the question of the technical feasibility and benefits to be gained from the installation of a real-time model with its associated applications arm8 there was considerable debate. While the concept had been around for some time, any success in attempting to implement this technology on gas pipeline systems has only come about recently, and even these results are not conclusive. With this understanding, NOVA has chosen to move forward cautiously in this area, testing the technical feasibility of various techniques at the same time as developing a business case for the implementation of a modelling system. In determining this business case, solid justification will be required prior to a large scale implementation project. In order to result in tangible benefits which cah be used to pay out the system, it must be possible to control the gas pipeline network either more effectively or with a higher level of safety with the modelling system than without'it. This can be done by condensing the quantity of data received by the gas controllers to higher level information which may be acted on without a lot of further analysis. Additional large amounts of raw data which can be produced by a modelling system are definitely not required or even useful in the minute to minute operation of the pipeline.

This content is only available via PDF.
You can access this article if you purchase or spend a download.