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| Screenshot from the EirGrid website. |
Eirgrid's
function is to match supply and demand from their control centre in
Dublin. As load i.e. demand increases, generating facilities have to be
switched onto the grid or increase their output to compensate, and vice
versa. They also have to be synced so their voltages match and AC
waveforms all start at the same point. One of the results of increasing
demand is that generators slow down, and frequency drops. The opposite
happens when load reduces. A change in frequency from 50 hertz can
affect clocks and timing, motors and other connected equipment, so
frequency is usually regulated to within fractions of a hertz (typically
0.03 hz). Anyone who has ever had an electric clock driven off the
mains, will know they keep relatively good time, in comparison to a
clockwork clock. That's because the speed of the shielded-pole motor
used in the mechanism to turn the hands depends on frequency, not
voltage.
Eirgrid's
Smart Grid Dashboard shows various parameters of Ireland's electricity
system, including frequency, daily supply and demand in GW, fuel mix,
interconnection imports, and CO₂ emissions. Historical
stats and real-time graphs of system parameters are also available on the EirGrid website. At 3 pm
today, demand is 5.485 gigawatt (GW) and wind generation provides 21.8%
of that. Peak demand is forecast to occur at 6.30 pm today and is
expected to be 6.34 GW.
1 GW = 1000 MW (megawatt) or 1,000,000 kW. Think of 1 GW as the power used by one million, one bar electric fires.
