Text Gerald Scheffels, Hans Robert Koch ––– Photography
In the past, there was distribution. For decades, energy was simply distributed in one direction – from continuously operating coal and nuclear power stations to transformer substations, and from there (once the voltage had been stepped down several times) to end consumers. To use a road traffic analogy, this quiet “one-way street” has now become a busy city-centre road network. Nowadays, the energy mix changes hourly with the wind and weather, so there essentially isn’t a reliable base load any more. In addition, wind farm and solar system operators feed in energy decentrally at medium- and low-voltage levels, so power grids now work in two directions. Heat pumps and electric vehicle charging stations mean higher consumption, while the long-familiar load profiles that peak in the early evening are now a thing of the past. However, both the quality of the supply and the 50 Hz frequency must be guaranteed at all times.
Grid operators are facing a mammoth task – they need to make their grids fit for these complex requirements. For naturenergie netze, this involves new construction work as well as modernising a number of existing transformer substations. The plants need to be adapted to suit the increasing demand for electricity, but that isn’t the only challenge. A bigger challenge is that they need to be adapted to cope with a much higher level of flexibility in terms of energy sources and flows and the precise control of electricity.
A DIGITAL TWIN
naturenergie netze (see text box) was quick to address these challenges and is currently working on a pilot project as it modernises one of its systems. The grid operator is using a digital concept to plan and configure its conversion of the Rheinfelden transformer substation. The new approach applies even to the preliminary work. Rainer Beck, a grid development coordinator, explains: “Before we start planning, we create a digital twin of the transformer substation, i.e. a virtual representation with all the data for both the live components (the primary technology) and the control level (the secondary technology) and, of course, for the buildings and all the peripherals. We then plan the conversion on the basis of this digital twin.”
Another reason why this is a challenging task is that the primary and secondary technology are planned using different CAD software tools. In this pilot project, this issue was resolved by a very special collaboration. As members of the VDE ETG “Digital twins for electrical energy systems” task force, two leading suppliers – entegra with its primtech software solution for the primary technology and Eplan for the secondary technology – had prepared for precisely what naturenergie netze needed for the first (preliminary) planning stage, namely combining primary and secondary technology in a single model.
MAJOR EFFICIENCY GAINS
For this unique project, entegra and Eplan were looking for an innovative distribution grid operator with a suitable pilot project to get involved as the third party in this collaboration. Contact with naturenergie netze came at exactly the right time – especially since the project in question was a complex one. As Rainer Beck explains: “The aim of the project is to renew all the secondary technology in an existing, highly complex transformer substation – and during ongoing operations.” It’s easy to understand why involvement in this project was appealing. “It would normally take two to three years to plan and implement the modernisation, but the new planning methodology will really speed things up.” Everybody involved in the project agrees. Matthias Schuy, Business Development Manager at entegra, explains: “What we’re doing here – integrating a transformer substation’s primary and secondary technology into one digital twin – has never been done before, but promises major benefits.” We asked him if he could give us a bit more detail. Rainer Beck: “Of course. Ultimately, we need to prove that the one-off investment will pay off quickly. After the first project phase – the preliminary planning – we see considerable time savings during the actual conversion of the transformer substations. What’s more, that applies to every project.”
ONE MODEL FOR ALL USERS
During the first stage of the project, the transformer substation was scanned, photos were taken of the rating plates, and the primary technology data generated was compared with the data from the asset management system. The result was a valid, functional primtech 3D model of the transformer substation. During a fully automated process, the datasets created in primtech were then exported to Eplan via an interface and used as the basis for planning the secondary technology in Eplan. Finally, the data from the secondary technology was integrated into the digital twin. This work is almost complete. By documenting the scenario as it currently stands, the basis has been provided for replacing the transformer substation’s secondary technology efficiently. “This is a really important step. All the data is verified. We basically follow the ‘single source of truth’ principle. The data in the original systems is left untouched and linked to the digital twin. This prevents redundancies that could prove problematic in the future,” explains Jan Oliver Kammesheidt, Global Vertical Market Manager Energy at Eplan.
In terms of the architecture of the combined data model, the parties involved – very much in keeping with the twin approach – have created a special infrastructure. “There’s no leading system – instead, there are merely different perspectives of one and the same model. The digital twin opens a window to the systems – for example, from primtech to Eplan or SAP. The digital twin therefore fulfils one of its main functions – namely offering centralised access to all relevant information for the transformer substation,” Schuy explains.
