Building Reliable Electronics to Achieve Kilovolt Effective Ratings Safely
Recent advances in hardware for handling direct current (DC) electricity have created an opportunity to greatly improve the efficiency, security, and safety of the U.S. power system while supporting new industries and grid design options. There remains, however, a significant technology gap in the safety and protection mechanisms required to mitigate potentially damaging faults in these systems. The projects that comprise ARPA-E’s BREAKERS (Building Reliable Electronics to Achieve Kilovolt Effective Ratings Safely) program will develop novel technologies for medium voltage direct current (MVDC) circuit breakers, applicable to markets including electrified transportation, MVDC grid distribution, renewable interconnections, and offshore oil, gas, and wind production. Project teams will either develop transformational improvements to conventional DC circuit breakers (i.e., mechanical, solid state, hybrid) or construct circuit breakers based on completely novel designs. These systems must achieve program goals of handling a voltage between 1 – 100 kV DC and power above 1 MW at extremely high efficiencies and fast response times.
Today’s power grid is powered primarily by alternating current (AC) electricity, from generation through distribution, to the consumer. DC power, however, brings a strong set of attributes for today’s evolving grid and beyond, including lower distribution losses and higher power carrying capacity. Battery storage and solar photovoltaic farms operate naturally over DC, and over 50% of electricity used in the United States today arrives as DC at its point of use. Moreover, DC power is extremely useful in industrial applications, electrified transportation, and resource production including offshore oil, gas, and wind power. Combined with recent advances in wide band-gap semiconductors, voltage source converters, and DC-to-DC converters, there is a significant opportunity to enable greater use of DC across these important applications.
The lingering risk of electrical fault scenarios (e.g., shorts and overloads) remains a primary hurdle preventing the growth of DC markets. In AC networks, electricity alternates direction periodically, naturally providing a “zero crossing” where no current flows for a brief moment, which allows electrical faults to easily be extinguished. DC networks, on the other hand, deliver power without zero crossings, which greatly increases the likelihood of electrical arcs in conventional circuit breakers, making them ineffectual in fault scenarios. BREAKERS projects will need to overcome this limitation while supporting greater power and voltage ratings than traditional low voltage solutions. Ultimately, innovations in MVDC circuit breakers could enable significant efficiency improvements in the United States, transforming how electricity is delivered and managed across the entire power grid, in transportation, and other valuable parts of the economy.
If successful, developments from BREAKERS projects will enable the development of fast, efficient, and reliable MVDC circuit breakers.
DC circuit breakers respond significantly faster than their AC counterparts, enabling prompt isolation and protection of assets from electrical faults.
DC microgrids could enable greater deployment and adoption of renewable resources, greatly reducing power sector emissions. Electrification of transportation (ships, aviation) with DC systems would also significantly reduce emissions.
Proliferation of MVDC systems protected by DC circuit breakers could drive higher energy efficiency, lower equipment costs, and bolster grid resiliency.