Egoli Gas is a natural gas distribution company based in Johannesburg servicing more than 7500 domestic, central water heating, commercial and industrial businesses in the greater Johannesburg metropolitan area. The company gets natural gas from Sasol which is then stored at a secure facility in Langlaagte, where it is carefully monitored and controlled. Confronted with an ageing system of network distribution monitoring and manual data collection, Egoli Gas saw the need to standardise and unify its systems to provide improved levels of operations and service delivery.
Project goals and challenges
The principal goal was to establish a comprehensive, unified and scalable gas network monitoring solution so that the company could:
* Monitor gas flow and pressures on remote inlet stations feeding the network.
* Monitor remote gas flow and pressure on governor stations throughout the network.
* Remotely monitor major customer consumption and pressures.
* Monitor pump station operations.
* Log critical network data for long-term evaluation in order to better address network load, leaks and requirements.
* Benefit from a business intelligence interface.
But, because of the nature of Egoli Gas’ reticulation topology, these goals would not be met without overcoming some difficult challenges that included:
* Remote sites do not have electricity – a site could simply consist of a manhole 3 metres above the gas pipes with no monitoring equipment. But since equipment is obviously needed, how can it work without an electrical supply and also, how does one make it vandal-proof?
* Radio telemetry was not a feasible option as there was no line of sight.
* Live installation - the gas network could not be shut down for integration, and all instruments and systems had to be implemented on a live network.
* Available GSM units could not be linked directly to the scada system as they have their own protocol.
* GSM transmission delays – because data transmissions are delayed, the data displayed on scada screens is not available in real time.
* Independent network – Egoli Gas did not want to be dependent on infrastructure such as ADSL lines, so a separate and independent network needed to be established.
Solution selection
Because of its ability to draft, design, test, engineer and develop special solutions that are not available off-the-shelf, Egoli Gas chose system integrator Systems Anywhere for the project implementation. In turn, Systems Anywhere chose a suite of Invensys Wonderware solutions that included Wonderware’s InTouch Scada/HMI (managed and standalone), ArchestrA-based System Platform, Historian and Historian Client. In addition Top Server UA from Software Toolbox would facilitate connectivity while TruTeq wireless modules would be used for communication and the TruTeq SmarToo units with simcards would be used for data capture and transmission to the TruTeq Starfish router. All the various disparate information sources would be collated in the purpose-built Systems Anywhere data warehouse.
“The Wonderware System Platform is the only solution that simplifies the ‘PVR’-type delayed data insertion into its Historian,” says Systems Anywhere MD André Vuilleumier. “With an impressive record of satisfied clients, Wonderware’s product suite could satisfy the widest range of the customer’s needs under a single technology umbrella.”
Implementation
The system uses the Internet for gathering remote site data through cellular modems. The remote sites have very little hardware intelligence in order to minimise electrical consumption from the batteries and solar systems supplying them. Standard analogue inputs and flowmeters route information through the industrial cellular modems. The modems facilitate store and forward logging through cellular Internet connection. Dynamic DNS allocation between the main sites allow OPC-UA to act as the main data highway between the control room and the storage site. Local installations of Modbus TCP and Ethernet TCP/IP connect some analysis equipment and the control system at the Cottesloe site.
“The battery-powered GSM units record the data locally and energy consumption was a key issue,” says Vuilleumier. “Perhaps the most remarkable and unique aspect of the system is the back-to-front flow of data from the remote GSM stations. The last two minutes of data are bundled and transmitted via GSM to the Systems Anywhere Data Warehouse in Cottesloe central control.
“These data are now ‘old’ but their time stamp is used to insert them into the Historian in the true chronological sequence. In a departure from the norm, ArchestrA scripting was used to display the data on the InTouch scada from the Historian, rather than from their source, which, by then was no longer in real time.”
The implementation took place between September 2011 and July 2012.
Business benefits
* Implementation of corporate standards.
* Improved decision-making ability.
* Better reaction to changing customer needs.
* Reduced remote site servicing costs – no more driving to sites to take manual readings.
* Increased operational transparency.
* Long-term network analysis is now possible.
* Rapid identification of leaks or illegal siphoning.
Operational benefits
* Near real-time data acquisition from the gas network.
* Long-term historical trending and analysis on data from disparate systems.
* Reduced maintenance response delays through faster, unified system feedback.
* More accurate verification of customers’ instantaneous needs from the network.
* Better assessment of gas usage trends throughout the year.
“In my view, the most outstanding features of the system are its scalability, the ability to make on-line changes and the unique way that time-stamped data can be inserted ‘back-to-front’ into the Historian,” says Vuilleumier.
Conclusion
Currently, 28 stations supply 7500 consumers which is close to the capacity limit. “In phase 2, we will be adding another 45 stations to the network and this is where the benefits of ArchestrA technology, corporate standards and standard templates will be most visible,” says Vuilleumier. “All the engineering work done to date will be able to be reused repeatedly which will reduce the implementation costs for Egoli Gas. A ninety-year-old system has been given a new lease of productive life thanks to twenty-first century technology.”
For more information contact Jaco Markwat, Invensys Operations Management, +27 (0)11 607 8100, [email protected], www.iom.invensys.co.za
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