Watching the cash flow – remotely, anytime and from anywhere around the globe. This is possible with a bio gas plant controlled by the right type of automation system. Farmer Huber simply uses his iPhone to check every day how much electric energy his 300 kW Combined Heat and Power Plant (CHP) has fed into the grid. The “energy farmer “, as he calls himself, seems to be very satisfied: “With my plant I provide clean electric energy for 450 households.
Right from the start I wanted remote maintenance and control. I am always on the go and simply do not have the time to personally look after things every day. Now I get a nice graphic visualization, showing updated status reports, operating time and the energy produced directly on the display of my smart phone.” The product behind it all is called netLINK SCADA which is a “Web visualization inside a PROFIBUS connector” coming from Hilscher. Simply attached to the PROFIBUS/ MPI interface of a Siemens S7 PLC and connected to the LAN network, the plug turns the simple process control system into a fully fledged automation station with monitoring and control functions.
The idea is as simple as effective: The plug itself contains the whole visualization pages. In the background, it reads the PLC data over PROFIBUS or the MPI programming bus and integrates them online directly into the pages. The pages can be addressed and displayed with any conventional web browser, such as Firefox® or the Internet Explorer®. Due to the use of pure HTTP Hilscher’s visualization solution is fully independent from the display platform. Visualizing with a local display using costeffective Linux-based terminals, or mobile via an iPhone or remotely via routers over the Internet – everything is possible with this solution.
Statistics published by the German Agency for Renewable Resources are a clear statement: 7,000 installed bio gas plants in 2011 represent a growth of 20% per year during the previous years. This gives us a clue as to the dimensions of the future needs of automation systems for this booming section of the resource saving energy production. Design and function of any bio gas plant follows the very same principle. Bio mass is fermented inside a fermenter.
The resulting gas is processed and used in a local CHP to produce electric energy or sold to serve as a substitute to natural gas. Mister Bernhard, Managing Director of GB Energietechnik, a service provider in the field of process automation states: “I fully trust in the plug. My initial skepticism was quickly removed after it was installed in the first bio gas plant. The quickly visible result via the web browser has convinced me.”He adds: “All that is needed is Ethernet across the plant, a terminal at each key position and VPN for remote access from any place outside the plant.
All this at only a quarter of the price of conventional visualization solutions.” The web visualization solution atvise® used for the plug is provided by an Austrian company named . Pages for data visualization are constructed with the atvise builder® software. Objects can either be designed with a built-in graphics design solution or integrated from libraries in the form of ready-made graphics in standard formats, such as jpg, bmp or tif.
After positioning the graphics a direct connection to any PLC variable can be established. The PLC variables to be provided,especially their symbolic information are directly imported from the original STEP7 PLC project and are abstracted to graphic data representations. There is no limit as to the number of variables, as it is usually the case with SIMATIC visualizations. One or several dynamic functions, such as rotating, moving or scaling, can be applied to a graphical object by referring to a specific variable as data source. Any of such actions can either be triggered by mouse clicks, keystrokes or by means of time-based activation.
There is no need for any HTML programming, which is one unique aspect of the solution. Instead, the HTML code required by the web browser is generated automatically by the builder at the time of uploading the program to the plug.Visually especially appealing is the use of vectorized graphics. Even with extreme zooming, there are no visible pixels and the visual representation always maintains maximum resolution. In addition, vectorized graphics only require a minimum of storage space. This means, one single plug is even able to visualize large-size processing plants. Thanks to event-driven data transmission, the web standard allows operating multiple visualization systems at minimum of network traffic.
For this reason, farmer Huber has decided to install two operator terminals at the plant on site, while using his PC at home to configure the system as third system. The DSL router of the telephone system serves as an interface to the Internet and uses a secure connection for stationary or mobile visualization devices.”There is no need for any additional installation. Instead, the plug simply needs to be connected and seamlessly integrates into the PROFIBUS/MPI/ Ethernet network. The solution is way ahead of conventional web visualization solutions, requiring tedious HTML programming,“ Bernhard emphasizes his satisfaction.
The simple, yet awesome visualization solution on the basis of standard web technology conforms with the general trend to rely on worldwide open standards independently from the visualization market. Proprietary solutions are usually not only cost-intensive, but also come with close ties to a specific vendor. For this reason, it is not surprising that costs start to explode as soon as a processing plant requires both process control and visualization.
Entry level PLC solutions are already available at a low costs, but being tied to a specific vendor usually leads to a big surprise, as soon as the costs for hardware and software of a visualization solution are stated. It is not seldom that the price of such a solution is three times that of the PLC itself. Especially with small installations, such as the one operated by farmer Huber, this cost factor represents a substantial percentage of the costs of the overall solution.
Today, a well working bio gas processing plant needs to have a ROI of only four years. The cost effective netLINK SCADA visualization solutions from Hilscher brings farmer Huber a great step closer to the fast success of his plant.
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Engineering Review – November 2019
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