Gasunie is a European gas infrastructure company that provides and manages the transport infrastructure of natural and green gas in the Netherlands and the Northern part of Germany. Founded in 1963 as gas trading company, it is now owned by the Dutch Government and is only responsible for the transportation of gas – some 120 bcm every year.
The company operates and maintains a 15,500 km pipeline network along which are numerous stations for the preparation and handling of the gas. These include 22 compressor stations, 19 blending stations, 93 regulating and metering stations, 14 export stations, 1,300 gas delivery stations, two air-separation stations and a number of storage facilities for Liquified Natural Gas (LNG), natural gas and nitrogen.
In 2013, a decision was made by Gasunie to put out a tender for a new standardised control system for it´s gas turbine driven compressor fleet in the Netherlands. Based on its engineers’ previous experiences with Rockwell Automation and thanks to the openness, flexibility, scalability and connectivity of the Rockwell Automation solution, coupled to Bilfinger Greylogix’s in-depth knowledge of the technology and the application, Bilfinger Greylogix was awarded the contract end of 2014 and Allen-Bradley products now form the primary control solution and complete automation layer for the control of gas turbines.
For the first project step, Bilfinger Greylogix´s job was to undertake a standardisation exercise. The project includes 50 gas turbines (eight different models built by three different OEMs) at nine locations and will deliver common operating schemas and procedures, in order to remove the ambiguity created by the deployment of multiple control systems.
Following the standardisation project, the main revamping projects were initiated in 2016. At the compressor station of Ommen, Bilfinger GreyLogix started the next step to replace six unit control panels (UCP) of two different OEMs, this will last until end of 2017.
According to Klaus Thomas, Team Manager Gas Turbines and Compression at Bilfinger Greylogix: “The unit control system of a gas turbine needs revamping every 15 to 20 years or so, even though the turbines themselves could have an operating life of some 40 years, depending on their working hours.
“The overall standardization project was instigated to create a common standard for all 50 UCPs,” he continues. “There would be a little variation, depending on the turbine technology, but the overall message was ‘what can be identical should be identical’. The UCPs really are the heart of the projects and as well as providing normal control and HMI functionality, they also have to reply on so-called special instrumentation for speed and vibration monitoring, which in this field is pretty specific due to the measuring-loop requirements above and beyond those used by other standard instruments. We also had to consider a solution that could handle different communication protocols and one that interfaced with a variety of third party systems.”
“It was a very long tender period and our proposal was based on a Rockwell Automation Integrated Architecture® solution from the beginning,” Klaus explains, “and I think this is one of the reasons we were awarded the contract. Gasunie used a lot of OEM systems from other automation vendors, but it already had experience of Allen-Bradley products and really liked the system. The project requirements also closely matched the functionality being offered by the Rockwell Automation solution.”
Primary turbine control is delivered by Allen-Bradley ControlLogix® programmable automation controllers (PAC), which communicate with HMI-based control solutions via OPC links. “The CPU requirements are actually very high,” Klaus explains, “but we were fortunate that Rockwell Automation had recently introduced the new ControlLogix 1756-L85E PAC, a more powerful CPU, which is more than up to the job.”
The main UCPs comprise two panels, one contains all the Allen-Bradley hardware, and the other contains all the other-vendor equipment like power supplies, terminal blocks, isolating amplifiers, fuses, Zener barriers, etc.
The safety solution was a primary element of the overall control infrastructure. “When dealing with natural gas we talk about intrinsic safety,” Klaus explains, “which we have to achieve using barriers or dedicated signal processing units that can work to ATEX standards. Additionally, we undertook a HAZOP/SIL to finalise the safety-related requirements of the system. We eventually developed a split solution, comprising a ‘normal’ CPU (ControlLogix) and a safety CPU (Allen-Bradley GuardLogix®) which is responsible for all functional safety requirements.
Another major facet of the project was the so-called special instrumentation. “At the project’s outset, Gasunie originally specified a solution based on an incumbent technology,” Klaus elaborates, “but we took the step of defining a system that moved away from this type of black-box technology and instead recommended the deployment of additional Allen-Bradley solutions for the vibration and speed measurements. Some other automation vendors can offer speed measurement, but not the vibration functionality required, another advantage offered by the Rockwell Automation architecture and its Allen-Bradley Dynamix™ 1444 units. It turns out that we didn’t need a dedicated system like the incumbent technology to realise the condition-monitoring capabilities we needed for these turbines, which have a specific time-critical function inside the UCPs and must offer response times of about 20 ms.”
Thanks to the standardisation exercise and the resulting implementation of the Rockwell Automation-based solutions, Gasunie now deploys a range of integrated solutions all running on a single platform supplied by a single technology vendor. As well as delivering the all-important familiar look and feel across all UCPs, maintenance will be significantly easier and spares stocking will be much more streamlined and efficient. Bilfinger GreyLogix was also awarded a service contract by Gasunie, including i.a. maintenance services, spare part management and provision of detailed Allen-Bradley systems information. The integrated solution is far simpler to scale or expand, too – although the architecture is likely to remain fixed for years.
“We saw major benefits of the Allen-Bradley-based special instrumentation,” explains Klaus, “The system cost was much lower per channel than the cost of the black-box incumbent. The other solution also required more space in a cabinet with additional wiring. Using this solutions, Gasunie sees data regarding vibration directly in the HMI/PAC, meaning it is instantly useable. Data logging into a database in real-time also allows instant contextualization of data, delivering greater real-time accuracy and for historical comparisons.”
Klaus then adds his thoughts about the relationship between his team and the Rockwell Automation engineers: “Each and every colleague of mine who had contact with the Rockwell Automation engineers was very happy, we built a great relationship based on co-operation. It really was perfect!
“With the standard we now have created for Gasunie, based on Rockwell Automation solutions,” he concludes, “we are looking to exploit other markets. We are not only focused on one type of system, we have very wide expertise in many technologies, but this is a great foundation. The Allen-Bradley components helped us create an optimum solution, which will now form the basis of others in the future. Indeed, we are currently thinking about projects at power plants in northern Europe and we are bidding for other revamp projects and all these proposals will be prepared based on Rockwell Automation technology.”
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