Circuit breaker for DC power grids investigated

1st July 2014

Siobhan O'Gorman

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There are many advantages to using direct current rather than the alternating current used today. For example, when using direct current there are 5-7% less losses in power grids and electric devices. Direct current also makes it possible to more efficiently feed electric energy from regenerative sources into power grids and energy storage and therefore it improves grid stability.

Funded by the German Federal Ministry of Education and Research (BMBF), the research project “NEST-DC” aims to investigate the foundations of an innovative semiconductor-based and completely electronic circuit breaker for DC power grids and applications. The circuit breaker should be able to switch direct current on and off as quickly and safely as possible, at voltages of up to 1,500V.

Until now, it has not been possible to fully explore the potentials of direct current because there has been a lack of efficient and cost-effective circuit breaker technologies. The only electromechanical circuit breakers available today cause a risk of arcing when switching direct current and voltages and are slow, heavy and expensive.

NEST-DC will explore innovative semiconductor components such as the Over Current Blocking Field Effect Transistor (OCB-FET). Structure and connection technologies and switching topologies for the circuit breakers that will use OCB-FETs are to be formulated and tested. There will be demonstrators for the project results in the areas of on-board aviation grids, electromobility and photovoltaics, as well as for direct current distribution networks.