High measuring data security and availability in the Linde Gas gas distribution network

• As part of the Gas business unit of Linde AG, Linde Gas is one of the leading gas suppliers in Germany and Europe.
• Special measuring stations need to be installed throughout the gas distribution network in order to record billing data.
• Together with Actemium Cegelec and Linde Gas Deutschland, Phoenix Contact has developed a solution for the secure transmission and recording of measured values.
• The solution guarantees a high degree of security and availability when it comes to transmitting sensitive measuring data.

At the Leuna chemical site, Linde AG operates one of the largest gas production centers in the world, which supplies a large number of consumers.

Linde Gas commissioned system integrator Actemium Cegelec GmbH to automate the measuring stations throughout the gas distribution network and to integrate them into the existing data management system.

In the gas distribution network, sensitive measuring data is transmitted via the Internet, which means that security and availability take top priority.

In order to record the measured values from the entire distribution network, an innovative communication concept based on an efficient protocol is required in order to link the individual stations to the data management system. The resulting data needs to be transferred continuously via the mobile network using GPRS/EDGE. All recorded measured values must also be stored in the respective measuring station to ensure that no data is lost if the connection is interrupted for prolonged periods.

The fact that the stations throughout the pipeline network are usually located in areas that are difficult to access also poses a considerable challenge. Thomas Hauswald, controller of the Bitterfeld site and pipeline networks at Linde Gas, is therefore in favor of a centralized system, which also permits a retroactive query of the data from the measuring stations.

When it came to data transmission, Kai Schwarz, Project Manager at Actemium Cegelec, who was responsible for the implementation of the project, opted for the Resy+ remote control solution from Phoenix Contact. In order to counteract possible interruptions to the connection in the mobile network, the measuring stations are connected to the data management system via VPN tunnel (Virtual Private Network) using the standardized IEC 60870-5-104 protocol.

By using the event-based standard, the data can be buffered in the event of short-term communication interruptions and sent once the connection to the data management system has been restored. The measured values are also stored on the controller's external SD card.

Central backup system for a continuous information chain

In order to ensure a seamless information chain, Actemium Cegelec integrated the Resy+ data management system into the heart of the solution.

The Windows service, which runs on an industrial box PC, provides the data management system with the main functions required for the retroactive reading of data. To this end, the data management system generates a query with the required information and sends this to the Resy+ data management service. The service retrieves the requested data from the respective station and converts the relevant values into the format favored by the operator. The data management system can use the generated results file to add the missing information to existing records.

The data is continuously exchanged between the data management system, the data management service, and the external stations via FTP. The user is presented with meaningful diagnostic information in the form of a text file. Linde Gas and Actemium Cegelec also chose to use hardware from Phoenix Contact. PSI-Modem-GSM/ETH modems, which establish the network connection and support industrial Ethernet networks, were installed in order to transmit sensitive data securely via the GSM network. ILC 170 ETH 2TX Inline controllers are used as the control technology.

By implementing the measuring stations on the basis of an industrial control and remote control technology, sensitive data can be securely transmitted to the data management system. “Central backup management also provides access to historical measured values, which are recorded in the controller as well as being transmitted via the IEC-60870-5-104 protocol”, reports Kai Schwarz.

Thomas Hauswald goes on, “The solution is based on innovative concepts in terms of both data security and the availability of the recorded measured values, which means it satisfies the most stringent requirements. It also provides us with a considerable degree of flexibility when it comes to maintaining and expanding the system”.