The liberalisation of the gas market has caused new demands to emerge for the collection and distribution of process data. For instance the nomination substitution procedure Online Flow Control (OFC) is now established for a contemporary and largely automated nomination of transport capacities and delivery quantities. The procedure necessitates a permanent and efficient collection and distribution of load flow data for customers.

With this in mind, the VNG – Verbundnetz Gas AG, Leipzig elected in 2005 to grant the market access to its high-capacity GPRS and VSAT based infrastructure. The service packet „Measurement Data Transfer” provides an efficient data transmission and distribution throughout Europe. It uses the infrastructure of the GPRS based network of the VNG and the available mobile radio network. Additional components were added to the network to collect, convert and transmit the data.

GPRS and Security
Solutions for data communication are quickly and flexibly implemented with mobile radio technology. The necessary GPRS technology can be applied practically throughout Germany and has approximately 98% availability in a 24-hour operation.

Only closed systems are used by the VNG to safeguard the customers’ data. A TDN-VPN solution is implemented in cooperation with T-Mobile. This is a separate virtual GPRS-based IP network without direct use of the Internet.

Communication Devices
The VNG use integrated computer systems with PC or IPC standards as data transfer devices. The devices, designed as Minimised Open PC Systems (MOPS) can transmit complex quantity structures from different interfaces and protocols. The flexible and reliable Linux operating system is implemented and configured with pertinent backup strategies for special application cases.

Skalar in use
The Skalar device from GÖRLITZ AG proved ideal to transmit volume measurement pulses. The device is supplied ex works with various communication modules (GPRS) and interfaces. Created volume measurement pulses are transmitted though a pulse module in conjunction with the application Skalar.online.

Integrated Data Transfer
The separate TDN-VPN networks ensure that the devices are easily integrated in the existing data transmission concept. The Skalar is implemented with emphasis on services for the OFC nomination substitution procedure. In most cases this deals with the transfer of volume measurement pulses from customer stations or for the transmission points to supra-regional and international energy suppliers.

The Skalar with its uncomplicated installation and coupled with the easy transfer of recorded pulses via GPRS takes full advantage of this environment. Devices are used in the customer stations and transmission points, they range from simple gas meters to log the operating volume to complex volume converters to output the base volume. This results in a variety of interfaces for the data sources. The expertise the VNG has acquired over the years enables it to service the increasingly complex interface scene.

Easy Implementation
The software SkalarBuilder from GÖRLITZ AG is used to configure the Skalar, it is then sent together with the relevant GSM antenna for installation. The accompanying instructions are followed to fit the device in a previously defined position by the end customer. After the initialisation the Skalar automatically establishes an online connection through its own TDN-VPN to a communication system at the VNG in Leipzig.

The data are relayed to different grid operators in conformance with the customers’ defaults. In addition to the data transmission via Tase.2, the data can be further transmitted if required in a Skalar specific mpx format or converted to a default format subject to the requirements of the grid operator. The VNG disposes of a highly-effective forecast module for an intelligent strategy to cover any potential breakdowns in the feeder system or the radio coverage.

Further Transmission of Data
The online data can be currently retrieved at 3 minute intervals. Pulse outputs from gas meters are used principally as a source. Extensive measuring systems can be coupled directly to the DSfG Bus. The interfaces currently used to transmit data to other grid operators are:

· Tase.2 via the Extranet in the despatch center
· Customised email formats
· Skalar-mpx format
· XML formats
· Pulse output
· IEC-104 if required via VPN over Internet

Communication routes are created user-specifically to meet the demands of the customer and data recipient.

Special Application Cases
As part of its services the VNG offers a mobile measurement of volume for the data collection. This is an innovative measuring and transmission technology combined in a portable device system. It can be brought on site at short notice and put into operation.

Summary
The VNG provides the service “MDT – Measurement Data Transfer” to support gas traders and grid operators with their business activities.

It is an efficient transfer and distribution throughout Europe of process data using state of the art mobile radio (GPRS/UMTS) and satellite radio technology (VSAT).

The communication technology is flexibly applied with existing mobile radio networks. It is suitable for areas without an extensive mobile radio infrastructure or as a redundant concept over the VGN satellite radio system for a secure and high-available transmission of sensitive data.

The VNG has installed MOPS and the Skalar from GÖRLITZ AG as data transmission devices.
In conjunction with MDT the VNG offers mobile ultrasonic recording of load flows. This covers the entire information chain from the data collection to the its transmission. Applying the expertise acquired over numerous years in the field of measurement and data transmission technology, the VNG has implemented its innovative techniques in umpteen locations.

For further details visit the website at http://www.mdt.vng.de