Electricity and Control March 2025

Transformers, substations + the grid

The digital revolution in transformer substations The energy sector is under a lot of pressure. In Germany, as in South Africa, and in most countries around the world, distribution grid operators need to adapt their grid infrastructure to meet the needs of the energy transition. Here, Eplan shares the case of collaborative work it is doing using digital twin engineering to modernise substations.

The energy transition means grid operators, globally, need to adapt their grid infrastructure.

B y 2030, some 80% of electricity is expected to be generated from renewable sources. A pilot project at naturenergie netze GmbH in Germany is demonstrating how transformer substations can be modernised more quickly. Working in collaboration with so–ware suppliers Eplan and entegra, this southern German distribution grid operator is now working, for the first time, on a digital twin that will speed up the planning and further development of transformer substations significantly. For decades, energy has been distributed in one direction – from continuously operating coal and nuclear power stations to transformer substations, and from there (once the voltage has been stepped down several times) to end consumers. To use a road tra†ic analogy, this quiet ‘one-way street’ has become a busy city-centre road network. Today, the energy mix changes hourly with the wind and the weather, so the familiar reliable baseload is no longer operating alone. 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, and the long familiar load profiles that peak in the early evening are not as consistent as they once were. However, the quality of the supply and the 50 Hz frequency still have to be guaranteed at all times. Grid operators are facing an enormous task – they need to

make their grids fit to meet 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, and the 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 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, that is, 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 challenge is that the primary and secondary technologies are planned using di†erent CAD so–ware tools. In this pilot project, this issue was resolved through collaboration.

26 Electricity + Control MARCH 2025