Frequency data for stable power supply
In the age of renewable energies, the grid frequency is becoming an increasingly important indicator of the stability of the power supply. An interdisciplinary research association under the leadership of the Helmholtz Association is analysing frequency fluctuations in twelve synchronous grid areas on three continents. For data recording, scientists of the Karlsruhe Institute of Technology (KIT) have developed a portable, GPS-synchronized recorder with a new measuring technology. The team has now reported on the first results in the journal Nature Communications.
The grid frequency and its fluctuations provide researchers from different disciplines with exciting information for the power grid. Above all, they show whether and to what extent the grid is stable, i.e. to what extent generation and demand are in balance. However, they also allow conclusions to be drawn about the effects of disturbances and outages and the influence of feed-in from renewable energy sources. International experts from mathematics, physics and engineering sciences have now measured frequency data in Europe, the USA and Africa and examined them more closely.
Electrical Data Recorder: High resolution frequency data
A research team of the Institute for Automation and Applied Computer Science (IAI) at KIT provided several novel recording devices for this large-scale measurement campaign of about 430 days in total. The Electrical Data Recorder (EDR) developed at IAI uses a GPS receiver for time synchronization and enables the recording of raw and frequency data with very high resolution. The device is portable and capable of transferring the raw data via a secure VPN tunnel directly to the "Large Scale Data Facility" database at the Steinbuch Centre for Computing of KIT, where they are further processed for research purposes. "Our recorder is not only high-performance but also practical to handle," explains Dr. Heiko Maaß of IAI. To start measurements at a specific location, the EDR only needs a power outlet. If no Internet is available, it can store the data locally for several weeks.
The bigger, the more stable: Frequency fluctuations depend on the network size
The equipment has now travelled halfway around the world for the collaborative research projects. The total of 1.27 gigabytes of frequency data from the 50 hertz or 60 hertz range, which form the basis of the current publication in Nature Communications, were recorded at 17 stations in a total of twelve different synchronous grid areas from continental Europe via the USA and South Africa to Iceland and the Faroe Islands. The comparison between the heterogeneous areas shows: The frequency fluctuations are significantly higher in smaller networks than in large ones. "The larger the grid, the more stable it is," explains Richard Jumar from IAI. "This finding confirms our previous assumptions that the intensity of the frequency fluctuations depends on the size of the grid. In particular, it confirms the underlying corresponding scaling law".
The scientists intend to make the data material obtained from the EDR measurements available to the international research community beyond the network. "Our investigations offer great potential - not only for the development of statistical models of frequency dynamics, but later also for better regulation of the power supply, which is increasingly being fed from volatile energy sources," emphasizes Professor Veit Hagenmeyer, head of the IAI Institute.
The study was conducted under the leadership of the Helmholtz Association (KIT and Forschungszentrum Jülich). Other consortium partners are Queen Mary University in London, Dresden University of Technology, and the University of Istanbul.
Leonardo Rydin Gorjão, Richard Jumar, Heiko Maass, Veit Hagenmeyer, G.Cigdem Yalcin, Johannes Kruse, Marc Timme, Christian Beck, Dirk Witthaut, and Benjamin Schäfer: Open data base analysis of scaling and spatio-temporal properties of power grid frequencies. Nature Communications, 2020. DOI: 10.1038/s41467-020-19732-7