Year after year, more producers in Germany are feeding renewable energy into the electricity grid. In 2020, their contribution amounted to 45 %. Good for the climate objectives of the Federal Republic – a challenge for the electricity grid: for the generation of electricity is dependent upon the sun, wind and rain and is distributed across several thousand producers instead of a few power stations. How can an electricity grid remain stable under these conditions – and how can this be achieved if 100 % of the energy ever comes from renewable sources? The Europe-wide research project EASY-RES has been considering this question since March 2018. With initial results, the project is now entering its final phase, in which a team of researchers from the University of Passau will play a central role.
“To ensure that an electricity grid is stable, it does not only need to have enough energy fed into it,” says Professor Hermann de Meer, who holds the Chair of Computer Networks and Computer Communications at the University of Passau and is the leader of the team of researchers from Passau. “Additional services are also required: for example, someone has to keep the current frequency in the grid constant and the grid must be surge-proof, i.e. it must automatically absorb small fluctuations.” Today, almost half of the electricity comes from small providers – but the grid is still stabilised centrally. “That is inefficient and instable,” says de Meer. If a solar farm out in the country feeds energy into the grid, why should the balance come from a power station one hundred kilometres away?Almost one third of the electricity in the grid is needed solely for the various stabilisation services."
When someone feeds in electricity and stabilises the grid, it must be possible to render an account of this and to pay for it.
Professor Hermann de Meer, University of Passau
"This requires elaborate infrastructure such as additional lines or even large power stations. There are large transmission losses and it is not environmentally friendly.” Therefore, one objective of EASY-RES is: anyone who feeds energy in should be able to contribute to the stabilisation locally. The researchers are developing a platform to allow thousands of small and medium-sized producers to network intelligently. The result: a virtual power station that not only provides electricity, but also stabilises the grid through, for example, the intelligent temporary storage of renewable energy. This will also have financial rewards for the smaller producers. “Keeping the grid stable is currently quite expensive and makes up a large part of the electricity price,” says de Meer. Accordingly, a variety of services come into this category: “These include frequency smoothing, the provision standby reserves, various reserve energies for maintaining frequency stability, and the maintenance of voltage stability by means of reactive power management.”
The researchers have completed the first project milestones: for example, they have carried out most of the measurements on the intelligent converters that the producers will later use to feed energy into the grid. “This data provides the basis for our work,” says de Meer. His chair is involved in the work on the platform that is later to link up the producers. “In Passau, we are now in the middle of the most exciting phase,” says de Meer. The requirements for the software platform are very high: it must be able to coordinate the access of thousands of devices, it must work safely even when faulty data is reported – and above all: it must not fail and must not be manipulable. “When someone feeds in electricity and stabilises the grid, it must be possible to render an account of this and to pay for it. These statements must be forgery-proof and must be able to stand up in court,” emphasises de Meer.
Computer scientists and engineers from several companies and electricity suppliers in Europe, as well as research institutions from Greece, Spain, the Netherlands, Great Britain and Germany, are involved in the project. EASY-RES is part of the EU programme “Horizon2020” and is being funded with a total of 4.5 million euros. As a lot of lab tests have been delayed because of the Covid-19 pandemic, the project has been extended by half a year – until the end of 2021.
