Technology:
Increased
power supply increases frequency, while decreased power supply decreases frequency.
Hence, electric power companies control output to keep frequency of their power
transmission networks stable because failure to stabilize the frequency leads
to power outage. NEC developed a technology to control power transmission and
distribution by seconds. The new technology measures frequency and monitors overs
and shorts of power using equipment installed in a lithium-ion battery. At the request
of electric power companies managing power transmission networks, it controls storage
and discharge of electricity automatically. It can control more than one
million storage batteries. Repetition of discharge and charge is supposed to
shorten the life of a lithium-ion battery, but the fluctuation of life can be
ignored as long as remaining amount is kept around 50%.
A company
that manages power supply of multiple buildings is called aggregator. Electric
power companies can reduce investment on equipment for the adjustment of power supply
and demand using the service offered by aggregator. Aggregators have great
presence in the U.S., but they are not widespread in Japan. NEC wishes to open
up the road of the aggregation business with this new technology. In addition, the
technology to manage a large number of batteries by remote control can be
applied to the smart city concept. In Japan, electricity retailing will be
liberalized in 2016. Because the output by photovoltaic and wind generation largely
depends on weather, NEC’s new technology to control and adjust power supply on
the second time scale will be of great help to the spread of renewable energy.
Various efforts are being made to establish
stable power supply (Tokyo Station at night)
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