Denka Wangdi at Emerson’s machine automation solutions business, USA, examines how edge controllers can help pipeline operators modernise and improve their systems by adding new capabilities.
With regards to realising good control and maximising uptime, pipeline operators face the same operational challenges as other process and manufacturing industries. However, there are also many operating and maintenance problems specific to pipelines that require careful attention by operators. Leading examples include leak detection, corrosion monitoring, and the surge control of equipment found in harsh, isolated environments. These issues are complicated, and are amplified by geographically diverse installations ranging over hundreds or thousands of kilometres.
Over the years, pipeline operators have adopted available technologies to address these issues, among others. Because so much of pipeline and pumping systems are existing infrastructure, it is very important that any new technical solutions are suitable for retrofit installations, in addition to new construction. One particular issue is achieving good telemetry from remote locations.
Control, co-ordination, communication, and care of pipeline operations can be improved with the latest edge processing capabilities. Edge controllers can perform all the functions of legacy control elements, while adding modern processing and communications capabilities. A processing element within an edge controller can enable analytics at the edge, and communications supports analytics in the cloud.
Conventional pipeline practices
Pipeline automation and monitoring systems often incorporate an assortment of technologies and methods, integrated and incrementally improved over years; 50% of pipelines in service today were installed in the 1950s and 1960s.
Basic monitoring and control at local sites have commonly been achieved using an assortment of remote terminal units (RTUs), programmable logic controllers (PLCs), or other dedicated devices. Their primary role is monitor-ing and controlling local equipment, but they must also have a means for communicating with other controllers, and with supervisory control and data acquisition (SCADA) systems which may be quite a distance away.
Leak detection and corrosion monitoring use specialised sensors and devices which must be integrated with local controls, so data can be transmitted and acted upon. In some cases, especially for leak detection, the information could be used to trigger automatic shutdowns or other methods of securing equipment.
Surge control can be a complex automation problem. Even maintaining consistent pressures and flows during normal operation requires careful programming. Transient conditions like equipment start-ups, shutdowns, or trips – along with valve operation – can precipitate undesirable pressure conditions if upstream and downstream controls, sensors, and equipment are not properly co-ordinated.
Adding edge control
Pipeline operators are familiar with traditional monitoring and control methods, but will find many advantages through adding to or superseding exist-ing systems with a modern class of edge gateways, devices, and controllers. These products are the result of evolving technologies, and are de-signed for installation right near the field processes. They can simplify the system architecture and are designed to provide superior solutions.
Edge gateways transmit field-sourced data up to supervisory systems using the latest protocols for best efficiency. Edge devices include gateway functionality and add the ability to perform information processing and calculations. However, the edge controllers are the most compelling advancement, as they can seamlessly include a comprehensive set of abilities.
An edge controller combines a real-time operating system (RTOS) with a general-purpose operating system (OS) such as Linux. The RTOS provides direct deterministic control like a PLC or RTU. The general-purpose OS enables capabilities such as advanced computing, analytics, and data storage. In addition, the general-purpose OS can offer more capable communication options, even over the low-bandwidth connections commonly encountered with pipelines.
The RTOS and general-purpose OS are completely independent from a hardware and software standpoint, but can communicate with each other securely using industry-standard OPC UA connectivity. This configuration preserves the robust, always-on RTOS operation while enabling modern computing capabilities.
Edge controllers can be integrated into existing systems to provide new capabilities such as data aggregation and analysis without disrupting proven operation; or, edge controllers can supersede PLCs and RTUs to provide a complete control, monitoring, and analytical solution for new installations.
Pipeline operators around the world work diligently to identify leaks quickly, proactively monitor and address corrosion issues, and optimise pumping operations. Edge controllers are a modern solution for the monitoring and control tasks previously performed by PLCs and RTUs, making them a good fit for new or retrofit projects so end users can operate their pipelines more efficiently.
Edge controllers include additional advantages such as better communication capabilities and general-purpose processing. This means optimisation and analytical calculations can be performed locally at the edge controller, using data from more sources than traditional control and monitoring systems. The analytical results can be transmitted to higher-level systems, or directly used at a local level to optimise edge control. Analytics enabled by edge processing can thus help pipeline operators solve problems and improve their bottom line.
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Read the article online at: https://www.worldpipelines.com/special-reports/18062020/control-from-the-edge/