Solar panels and wind turbines are only part of the energy puzzle. For green power to flow without obstacles, the grid itself needs new devices. Researchers from the European SSTAR project replaced the classic transformer with a magnetic core by power electronics and checked whether such a system can cope with high voltage. The test results are promising — and at the end you can check whether you have what it takes to be a grid engineer of the future.
The energy transition is usually discussed in terms of wind, sun and water, that is, the sources of power themselves. Yet changing the sources is only half the job. Energy from renewable installations still has to be transmitted and distributed, and that takes new grid infrastructure, and urgently.
“The energy transition needs power grids that are more flexible, digital, resilient and capable of integrating high shares of renewables,” says Jonatan Peris Rivas of the Spanish foundation CIRCE, which coordinates the EU-funded SSTAR project.
The hero of the project is the solid-state transformer, SST for short. It is an advanced power electronics device in which the classic transformer with a magnetic core is replaced by semiconductor switches operating at high frequency. It sounds like a design change for specialists, but in practice it moves a key element of the grid into the world of electronics.
The SSTAR team set itself a concrete goal: to take this technology beyond the low-voltage stage and prepare it for work in high-voltage grids. The idea was to show that high-voltage SSTs can go from concept to prototypes validated in experiments, backed by credible data on performance, safety and sustainability.
Work went on in parallel in three directions. Each answered a different challenge, from materials through the electronics itself to the way the whole system is controlled:
The first line shows that modern power engineering is not only about semiconductors. To insulate the elements of the prototype, the team prepared a fluid of plant origin. A 200-litre sample was produced, intended for use in the transformer prototype. In this approach, being green concerns not only the source of energy but also the materials the equipment itself is made of.
The second and third lines are closely linked. The high-voltage module transfers energy in both directions thanks to inductive power. The decentralised architecture, in turn, means that individual modules can be connected in series and their number increased without a single central controller supervising the whole. Such a design is meant to make the solution easier to scale.
All the elements were integrated and validated in two certified testbeds. The prototype based on IPT technology achieved 76.7 kW of power transfer at 1 500 V, and its efficiency under resonant operation was around 95%.
The test of the cascade version turned out just as interesting. The researchers connected 28 modules in series and simulated grid conditions of 66 kV at 100 A RMS. This corresponds to 660 kW per branch, and all of it without a central controller. The results confirm both the scalability of the system and its technical effectiveness.
The team did not limit itself to electrical measurements. A sustainability assessment was carried out as well. “Our subsequent sustainability assessment showed that the SSTAR concept can significantly improve environmental performance, especially when powered by renewable electricity,” says Peris Rivas.
The researchers also pointed to the places where the new technology has the best chances. They named industrial microgrids, data centres and offshore renewable energy installations as the most promising.
According to the team, the project has marked out a clear path towards high-voltage solid-state transformers that are technically promising, more sustainable and relevant to real grid needs. SSTs themselves have become a serious technology supporting systems built on renewable energy sources.
“The project did not stop at laboratory ideas, it produced validated prototypes, a sustainability and social assessment, and a clear roadmap to achieving technical maturity,” stresses Peris Rivas. He sees the combination of technical solutions with a vision at the level of the whole system as the project’s greatest success. Building on the results, the researchers are developing the prototypes further, looking for industrial partners, investments and new funding opportunities.
The energy transition is not only about new sources of power but also about new devices in the grid itself. The SSTAR project showed that solid-state transformers can step out of the laboratory and work in the high-voltage range, with high efficiency, a scalable architecture and plant-based insulation. For students of energy engineering, electrical engineering or electronics, it is a good example of how many fields meet in a single device: from insulating materials, through power electronics, to control systems.
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