Electronic DC circuit breakers for the smart grid

February 14, 2017 // By Graham Prophet
Researchers in Germany have developed power electronic circuit breakers for DC smart grid applications.

It has long been proposed that high-voltage DC transmission and distribution could offer significant  efficiency gains over today's use of AC. A major barrier to the adoption of such a scheme is the absence of an effective and reliable circuit-breaker function. Any high current, when interrupted by a physical gap, will cause an arc to strike. With the polarity reversals of AC, arcs can be readily extinguished or controlled: DC is much more challenging. 

Led by researchers from Infineon, the "NEST-DC" project is looking at DC power grids, establishing the technological basis for high performance electronic (as opposed to electromechanical) breakers.

The German research team has explored the technological basis for reducing the energy losses in power grids and electric devices by more than half through the use of DC. The five project partners from industry and science investigated the foundations of a semiconductor-based and completely electronic circuit breaker that can be used for future DC power grids and applications.

The new circuit breakers will be able to switch on direct current as quickly and safely as possible and, in case of emergency, switch it off in the shortest possible time. They will enable more efficient feeds of energy from regenerative sources into power grids and energy storage, and will improve grid stability. With direct current it will also be possible to build much more compact electric devices. Infineon Technologies AG was the team leader and worked on the circuit breakers together with Airbus, E-T-A Elektrotechnische Apparate GmbH, Siemens AG and the University of Bremen’s Institute for Electrical Drives, Power Electronics, and Devices (IALB). The European Centre for Power Electronics e.V. (ECPE) provided further support. The ECPE is headquartered in Nuremberg, Germany.

Among other aspects the project partners explored new semiconductor components such as the Over Current Blocking Field Effect Transistor (OCB-FET). New structure and connection technologies were formulated and tested as