Computer Control of Gas Transmission

Abstract

Abstract The Alberta Gas Trunk Line Company Limited are now completing an automation program which permits basically " unattended" operation of field facilities. Gas receipts and deliveries are controlled from a Dispatch Centre in Calgary. A dispatcher obtains required gas flows into the system by the issuance of flow orders to the producers. Gas transmission and deliveries are controlled by the dispatcher's issuance of telemetered commands to field equipment. A supervisory system has been installed, consisting of master station equipment in the Dispatch Centre and remote supervisory panels at major field facilities. Telemetering is accomplished over leased circuits that are also used for voice communication. The supervisory system gathers and stores field data from major receipt, transmission and delivery points. It alerts the dispatcher of abnormal conditions requiring his attention. It performs computations and displays information to assist the dispatcher in proper courses of action. The supervisory system also enables the dispatcher to implement commands directly to field equipment. The computer is an integral part of the supervisory system. It performs many supervisory functions that alternatively would require hard wired equipment, and is justified by these savings alone. The computer's computational and storage abilities also provide information that would be impractical to obtain by other equipment. A third advantage of the computer is the flexibility of its operation, which allows many modifications and additions to be made by minor program changes. The computer currently performs many tasks, but it is still idling much of the time. New assignments are being written, and it is expected that the computer will play a larger role in years to come. The automation of its facilities is enabling Alberta Gas Trunk Line to cope with a rapidly expanding system, and is resulting in a better and more efficient operation.