Concentrators help regulate Slovenian gas flows

Edited by the Engineeringtalk editorial team Dec 9, 2003

Novel data concentrator modules are being used in a gas distribution system in Solvenia to collect and forward calculated mass flow data to a Scada system.

A novel data concentrator module is being used in a gas distribution system in Solvenia to collect and forward calculated mass flow data to a Scada system.

The data concentrators also support web pages.

These can be accessed by browsers, which connect directly to the data concentrator.

This allows the mass flow data to be viewed in real time, allowing gas customers to monitor their own gas consumption rates.

The Slovene gas network has two connections with foreign grids: Austria in the northeast, and Italy in the west.

These connections allow Slovenia to be a part of the comprehensive European gas network.

The state-owned natural gas company, Geoplin, is responsible for importing and the transport of natural gas throughout Slovenia and across the border to Croatia.

A main pipeline carrying natural gas from Russia crosses the Austrian border, and travels 269km across Slovenia to join a pipeline at the Italian border, carrying Algerian gas.

A compressor station and main branch line transports gas to Croatia.

A further 500km of distribution lines supply Geoplin's users within Slovenia.

During a recent upgrade to the Scada system at the main compressor station, a new pilot scheme was introduced that allows Geoplin customers (local gas supply companies) to monitor their own gas flow rates, enabling them to reduce flow rates at peak times and thereby reduce supply costs.

To comply with the European gas deregulation laws, the Scada system includes an accounting and customer billing system.

Data from remote metering sites across Slovenia serving between 200 and 300 customers are fed back to this station at Geoplin's headquarters in Ljubljana using one of two methods.

At larger metering sites, where remote terminal units (RTUs) are installed, data are input into the system from existing mass flow computers.

At smaller sites, ten data concentrators supplied by Lee-Dickens are used to collect mass flow data from a mass flow computer comprising pressure, temperature and flow devices, and a volume corrector.

The Lee Dickens data concentrators can connect to up to three pairs of mass flow computers (and therefore three customers) and send data back every hour via GSM to the central server at the main compressor site.

These data are logged and can then be accessed by authorised maintenance personnel at the individual gas companies using an Internet browser.

This enables them to monitor their own gas flow rates and for an engineer to adjust flow rates accordingly.

This is especially important as customers are charged increased tariffs during peak periods such as winter mornings, and Geoplin customers are set a maximum demand limit during these periods.

By monitoring during high usage periods, customers can check that they are not in danger of breaching this maximum demand limit and that they can ensure they are not charged the higher tariffs, by simply reducing flows.

The data concentrators were the natural choice for the main contractor because they are less costly than RTUs and extremely reliable in the field.

The data concentrators, which in this case are 24V DC powered, are mounted in tough glass-fibre enclosures alongside each of the metering facilities and fitted with either PSTN or GSM modems, as required.

As the project grows and more customers come on line, there is a planned requirement for a further 200 to 300 data concentrators over the next 2 years.