Intelligent Transformer A Heart for Electricity

Marco Liserre and his team have developed a modular, intelligent transformer.
Marco Liserre and his team have developed a modular, intelligent transformer.

The change to renewable energies has an impact on the entire power grid. A stable grid must be durable, flexible, fault tolerant and efficient. The University of Kiel makes an important contribution to this.

For five years, the Christian-Albrechts-University Kiel has been researching components for the power grid of the future in the HEART project (The Highly Efficient And Reliable smart Transformer). The team led by Marco Liserre from the Chair of Power Electronics has now developed a smart transformer for this purpose.

The new »Smart Transformer« incorporates power semiconductors made of silicon carbide that enable a high degree of efficiency. The special feature of the new transformer is its modular design. It not only makes it usable for the power grid, individual components help to better integrate charging stations into the power grid or to better connect DC grids to the central AC grid. The system can also be used in energy storage systems.

Putting it through its paces

But is the new transformer really suitable for everyday use? To prove this, the scientists have set up various test environments. Among other things, the focus was on the thermal load capacity of the components. The newly developed »Active Thermal Control« and »Power Routing« methods can reduce the thermal effects of fluctuating current flows and generate new data. »From this data, we derive how we influence the temperature and make the modules more stress-resistant for fluctuating power supplies,« says Liserre.

The question now is whether the modules can interact with the real power grid. For this purpose, a second test environment was created with which the power grid can be simulated in real time. In this way, researchers can test how the Smart Transformer works in conjunction with the power grid and whether it delivers the required performance. Other test scenarios are also possible: the cooperation of transformers with wind energy systems, storage systems or solar cells and their interaction with the power grid.

The researchers found out that the Smart Transformer brings the various energy sources better into the power grid and that the process is easier to control than with conventional transformers. In addition, the new transformer has a longer service life and is more reliable than conventional transformers.

New medium-voltage laboratory

But the tests to date are not enough for the researchers. A new medium-voltage laboratory makes further test steps possible. The scientists can test the prototypes in the 10 kV and 1 MW range and simultaneously run real-time simulations. At the same time, the scientists are carrying out practical tests in Scotland. The researchers are working together with Scottish Power. By 2022, the Smart Transformer is to be used under real conditions in the Scottish power grid.

In addition, the Kiel researchers want to find out what effects the further expansion of renewable energies will have on nodes in the grid and what interventions an intelligent transformer can make in the grid without putting a strain on it. An expansion of the research laboratory for energy storage is also planned. Marco Liserre can imagine marketing the transformer in cooperation with companies or setting up his own start-up.