Solving a problem that has handicapped use of high-voltage direct current (HVDC) in transmission lines, networks, and power grids for more than 100 years, multinational power engineering giant ABB has announced that it has designed and developed a hybrid DC breaker capable of interrupting DC power flows “equivalent to the output of a nuclear power station within five milliseconds… as fast as a honeybee takes per flap of its wings.”
The hybrid DC breaker combines “advanced ultrafast mechanical actuators with ABB’s in-house semiconductor IGBT valve technologies or power electronics.” ABB management deems it a “game changer.”
Capable of carrying electricity over long distances much more efficiently than alternating current (AC), HVDC transmission is seen as a way of transporting renewable energy from remote utility-scale locations — such as desert solar power facilities and offshore wind farms — to consumption centers at much lower cost than existing transmission infrastructure.
Stopping HVDC Flows Faster than the Blink of an Eye
According to ABB, the breakthrough hybrid DC breaker “removes a significant stumbling block in the development of HVDC transmission grids where planning can start now. These grids will enable interconnection and load balancing between HVDC power superhighways integrating renewables and transporting bulk power across long distances with minimal losses,” technology manager for grid systems and HVDC grids program manager Magnus Callavik writes in a Nov. 7 post on the ABB Conversations blog.
“DC grids will enable sharing of resources like lines and converter stations that provides reliability and redundancy in a power network in an economically viable manner with minimal losses. ABB’s new Hybrid HVDC breaker, in simple terms will enable the transmission system to maintain power flow even if there is a fault on one of the lines.” [sic]
ABB’s hybrid circuit breaker is capable of blocking and breaking DC currents at thousands of amperes and several hundred thousands of volts, equivalent to the average power consumption of 1 million Europeans.
“It amounts to stopping power capable of feeding a large city much faster than an eye blink!,” ABB elaborates. “This speed helps protect the DC transmission system and prevent power outages in new low loss compact power superhighways. The next step is to install the breaker in pilot installations.”
Edison and GE May Have Lost the Battle of the Currents…
Promoted and developed by Nikola Tesla and Westinghouse, alternating current (AC) in the early 20th century won the so-called “War of the Currents” versus DC, which was promoted and sponsored by Thomas Edison and General Electric. AC has since become the predominant form of electric current used in transmission lines, grids, buildings, and homes.
There are advantages to using DC at local and much smaller scales, however, according to ABB. DC is still used to distribute electricity — particularly in remote and isolated communities — and numerous and varied equipment and devices produce as well as run on DC (including batteries, solar panels, and wind turbines on the production side; and computers, cell phones, and LED lights on the consumption side), ABB notes in “Tesla vs Edison: the war of currents.”
“At the moment, each of these appliances uses its own rectifier to switch power from AC to DC. A much more efficient solution would be to convert the power in a larger rectifier as it enters each building. ABB estimates the savings from using DC instead of AC in buildings could be in the order of 10 to 20 percent. Losses could be further reduced by converting power to DC at the substation level and distributing DC power throughout an entire district, or even by transmitting, distributing and using power as DC.”
Building out DC distribution grids where AC counterparts already exist would be impractical, ABB acknowledges, but it sees DC as a “solution of choice” in newly built areas or cities, as well as for communities and installations that are off the grid at present. “Such islands include new ships and communities generating their own power from renewable resources,” ABB says.
Furthermore, ABB points out, “DC distribution would be particularly attractive for communities using power generated by photovoltaic solar panels, since this is already DC power and currently has to be converted to AC before distribution.”
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