Articles from "Microelectronics News"

Fraunhofer Group for Microelectronics

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The power grid of the future will minimize energy losses

When electrical energy generated from renewable sources arrives at your wall-plug, it has usually been on a long journey – whether from offshore wind farms or regional solar, wind, and biogas power plants. New electronic devices from the Fraunhofer Institute for Integrated Systems and Device Technology IISB are now to be used to prevent large quantities of this energy going missing en route to the consumer.

 

Cars and trucks race down the freeway, turn off into the city, wait at the traffic lights, and then crawl along through side roads. Electric current flows in a similar way – from the power plant via high-voltage lines to transformer substations. The flow is regulated like at traffic lights. Then cables bring the power into the city center. A number of transformers step down the voltage to allow appliances a continuous supply of low-voltage current. Thanks to this highly complex infrastructure, customers can just flick a switch and their coffee machine starts up. The basis for continued functionality of all appliances is a secure and stable electricity supply. In the future, electric vehicles will ensure that the traffic system and the power grid come even closer together. The vehicles’ batteries will serve as intermediate storage when more power is being produced than consumed.

Overcoming long distances

Large projects such as Desertec are intended to supply Europe’s future power needs by building solar-thermal power plants in the sunniest regions of North Africa and the Middle East. The energy will then be sent to consumers via high voltage power lines or undersea cables. Now existing cables, systems and devices need to be adapted to this future mix of energy sources to ensure that power arrives securely at the consumer with minimal losses. The power electronics experts at Fraunhofer IISB are working on technical solutions. They are developing components and systems to convert electrical energy and making it safe and reliable.

The solution: high-voltage circuit breakers

Today, direct current (DC) is used more and more often for carrying energy across distances of more than 500 km, or through undersea cables. This has a constant voltage and, compared to alternating current (AC), it only loses up to seven per cent of the energy across great distances as opposed to up to 40 per cent. At the same time, additional frequency converters have to be used to convert DC back into the AC that consumers need. Together with Siemens Energy, Fraunhofer IISB is working on developing high-voltage circuit breakers. These are needed for carrying DC across the power grid, and are a decisive requirement for projects such as Desertec. In order to satisfy the requirements of future energy supply grids, the switches must be more reliable, more easily scalable, and more flexible in their application than existing solutions. To this end, the researchers are using more cost-effective semiconductor cells that could not be used for high- voltage DC (HVDC) transmission with existing circuit technology. There is a power frequency converter station at each end of a HVDC transmission system. Devices that can be switched off and can be operated at higher switching frequencies will serve as frequency converters, as they allow for smaller and more easily controllable systems. Protecting the cells against critical failure is a big challenge. Of the approximately 5,000 modules connected in series in a converter station, only a few may fail and, if they do, it must not affect neighboring modules. Otherwise a chain reaction could destroy the entire system. In conjunction with the cooperation partners, a solution has been found to this problem, and research into tailor-made materials and devices continues to ensure that the devices and systems of the future require less energy.

Contact:

Dipl.-Ing. Markus Billmann
Phone +49 911 23568-20
markus.billmann(at)iisb.fraunhofer.de

Dr.-Ing. Bernd Fischer
Phone +49 9131 761-106
bernd.fischer(at)iisb.fraunhofer.de

Fraunhofer Institute for Integrated Systems and Device Technology IISB
Schottkystrasse 10
91058 Erlangen
Germany
www.iisb.fraunhofer.de