Energy is more expensive than ever. In the course of the energy turnaround and the current political situation, the expansion of renewable energies is intended to contribute to climate protection, but also to make us economically less dependent on fossil fuels. However, especially in the case of wind and solar energy, grid bottlenecks are currently still preventing optimal use of the energy generated. In the EU-funded research project “Grid4Regio”, Darmstadt University of Applied Sciences (h_da) is working together with e-netz Südhessen AG and Darmstadt Technical University to better exploit the potential of existing grid infrastructure at regional level, to relieve the transmission grids …

… and thus counteract the sometimes controversial grid expansion.

The Binselberg near Groß-Umstadt on the edge of the Odenwald. Four large wind turbines generate energy here, which is fed directly into the regional power grid. So far, so good. But what happens on days when the wind turbines generate more energy than the grid can absorb on site? Currently, due to a lack of storage options, either the loss of precious energy must be accepted or the surplus energy is “pushed up” into the upstream high-voltage grid. Prof. Dr. Ingo Jeromin from the Department of Electrical Engineering and Information Technology at the h_da calls this the “energy highway”.

Accordingly, the region’s medium-voltage grid is the interstate highway and the high-voltage level is the freeway. If, during increased traffic on the federal highway, everyone briefly takes the supposedly faster route via the freeway and then the exit again in the direction of their destination, a traffic jam occurs at the interchange. If congestion persists, in many cases the highway network is expanded -the same is true of the power grid. In the end, both mean: additional costs for taxpayers.

Prof. Dr. Ingo Jeromin is convinced that this does not have to be the case. Together with his project partners, he wants to show that by using new technologies and systems, renewable electricity can not only be generated on site, but also consumed directly. “Why build new electricity highways when you can use the existing, passable federal highway? With our project, we want to help find a solution to keep the expansion of renewable energies and the associated costs as low as possible by using the existing energy as efficiently as possible.”

In concrete terms, this means that the “surplus” regenerative energy from wind and sun in the medium-voltage grid in the Groß-Umstadt region is to be redistributed to other communities in the region, such as Babenhausen or Groß-Bieberau, instead of being fed into the upstream high-voltage and extra-high-voltage grids and thus burdening them. The idea of the research team: Neighboring networks are to be coupled in a decentralized manner using already existing infrastructure in order to make the best possible use of it. The model region in which this approach is being investigated is in the network area of e-netz Südhessen AG, which initiated the project.

The h_da Research Group for Sustainable Energy Systems (daFNE) led by Professors Ingo Jeromin, Athanasios Krontiris and Klaus Martin Graf plays an important role in the project. By means of a network control center simulator designed at the h_da, concrete usage scenarios are to be run through and then transferred into a training and education concept for specialists from the energy and network industry, e.g. employees of distribution network operators. These scenarios are based on the research results of the department “Electrical Energy Supply Using Renewable Energies” at the TU Darmstadt, headed by Professor Jutta Hanson.

“In order to be able to map the conditions in the region correctly, we first have to understand the networks and the various usage scenarios correctly,” says Prof. Dr. Ingo Jeromin, describing the challenge. “Due to new influencing factors such as electromobility or the increased use of heat pumps, a lot is changing right now in terms of grid usage by end consumers. With these unknown variables, it is currently still difficult to calculate.”

The simulation of the network system of the model region and the associated cross-connection control center of e-netz Südhessen AG, which is available in the computers of the researchers, helps here. “We would like to develop a kind of blueprint for German medium-voltage grids and possible load situations on the basis of the data supplied by the TU on our model region, so that we can use it to create realistic schedules for various scenarios,” Jeromin explains. “In the future, switchmasters throughout Germany could thus be able to assess in their regional control rooms which switching operations are necessary to avoid overloading train path XY.”