Gas and Electricity Supply and Monitoring Systems

Have you noticed that there are hardly ever any staff at gas and and electricity sub-stations, even at large installations, except maybe for a security man walking around? It's been like that for a long time, because operators are interested in what is happening over a wide area, rather than any at single location, and they get their results by telemetry. The people who manage gas and electricity supplies normally work in front of consoles at their company offices, which might be nowhere near any of the local sub-stations.

This page briefly describes just one documentation project I have worked on. For details of my other projects, see my home page.

During 1988 and 1989, I worked for one year on the documentation of a control and monitoring system for gas and electricity supply that was being developed by Westinghouse Systems. Simulated data, compatible with real data that might be collected by telemetry from remote gas and electricity sub-stations, was fed into a VAX/VMS computer, and processed using software which was under development, based on the Habitat database application. Results were displayed on two types of console, SIGMEX and AYDIN.

Gas and electricity supplies come from a variety of sources which are not always dedicated solely to the use of consumers via the national grid. For example, some large industrial users such as oil refineries and chemical plants use so much electricity that it is worthwhile having their own generating plants. They are often capable of producing more than they need for themselves and sell off the excess to the National Grid. The requirements of the Grid vary with the time of day, the weather, and a variety of other circumstances such as people putting the kettle on when the Cup Final has just finished. When domestic demand for electricity is low, some industrial suppliers might buy it back at a lower price.

The distribution of gas is also subject to a supply and demand chain, although it is managed by storing it up, rather than switching supply stations on and off. Domestic consumers pay the same price for gas, regardless of the time of day, but further up the supply chain the price varies according to demand. We are all accustomed to the sight of large gas holders which go up and down. They are high in the morning because they are full of gas, and low in the evening because the gas has been used up. That sounds simple enough, but there is also a financial consideration. The local gas suppliers are making money by purchasing gas at night when it is cheap and selling it off to consumers during the day. Therefore, the amount stored up at night might be a lot more than is needed to supplement the regular gas supply during peak daytime hours. It all depends on economics, and the forecasting methods that are used to anticipate demand.

There are, of course, things that might go wrong at gas and electricity sub-stations. For example, the failure of valves or switching systems might create situations that require attention. If the fault cannot be rectified by telemetry, an operator is sent out to deal with it.

During my time at Westinghouse I wrote documents for use by operators and technicians, describing how to use the Habitat-based software to monitor gas and electicity supplies from SIGMEX and AYDIN consoles. Some of these consoles were available at the Westinghouse site, but they also had PCs which would display a similar type of user interface.

I would be interested in any documentation projects on gas and electricity supply systems or other related activities. Please get in touch with me if you have any enquiries.

Copyright 1999

Mike Gascoigne, Write_on
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