"ABB's circuit breaker changes that. Within five milliseconds it can stop the flow of a huge amount of power—equal to the entire output of a nuclear power plant, ABB says. The breakers could be used to nearly instantaneously reroute power in a DC grid around a problem, allowing the grid to keep functioning. “Ordinarily, if something goes wrong anywhere, all the power goes off,” says Claes Rytoft, ABB’s chief technology officer. “The breaker can cut out the faulty line and keep the rest healthy.”
Researchers have been trying to develop high-voltage DC circuit breakers for a century (see “Edison’s Revenge: The Rise of DC Power”). Mechanical switches alone didn't work—they shut off power too slowly. Power electronics made of transistors that can switch on and off large amounts of power offered a possible solution, but they proved far too inefficient. ABB's solution combines power electronics with a mechanical switch to create a hybrid system that's both fast and efficient. The new circuit breaker could also be far less expensive than systems that use only transistors.
“The cost of the power electronics breaker was humongous,” says Ram Adapa, a power delivery technical leader at the Electric Power Research Institute. “The hybrid breaker should be less costly.”
With the major hurdle to DC grids out of the way, ABB is now developing algorithms to control them. The system will still need to work in concert with AC lines for distributing the power in local communities, since there is no inexpensive DC equivalent of the transformers needed to step down power to the relatively low voltages used in homes and businesses. One of the first markets for the new technology could be Germany, which has decided to turn off its nuclear power plants and rely heavily on renewable energy (see “The Great German Energy Experiment”).
The degree to which high-voltage DC grids can help renewables may depend on the economics of installing underground cables versus overhead lines."
AN : ABB's innovation is a significant advancement for the grid.
Via Arno Neumann