By Bruno De Wachter / Published on Thu, 2009-01-29 06:30
On blackouts and cascading failures
An article in Scientific American last month discussed an interesting analogy, namely the one between the electricity network and global financial networks.
According to the author Jeffrey D. Sachs, both are network systems in which a local problem can undergo a system-wide amplification leading to a general catastrophe. Such amplification is caused by what Sachs calls 'rational panics'. Each node in the network has certain rational rules that are created to protect its own stability. However, if all those rules should conclude simultaneously to withdraw from the system, the whole network starts collapsing.
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By Hans De Keulenaer / Published on Fri, 2008-04-11 21:50
A range of services necessary to the efficient running of the electricity system which are outside the basic needs of energy, generating capacity, and power delivery. Some of these (such as regulation and reactive power) are required during normal operations to maintain the necessary balance between generation and load in real time and maintain voltages within the required ranges. Other ancillary services (such as contingency reserves) provide insurance to prevent minor problems from becoming major catastrophes.
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By Stephen Browning / Published on Wed, 2007-11-28 18:16
Most thermal fossil fired generation is designed to be most efficient at full load. Large coal and oil units are typically 36% efficient at max ouput dropping to 32% at half load. CCGTs can be 55% efficient at maximum, but only 40% when at half load.
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By Stephen Browning / Published on Wed, 2007-11-28 15:21
The demand is continually changing, thus generation has to be scheduled and dispatched to track it, plus provide adequate response and spare, which can react in the appropriate timescales to cater for innacuracies in demand prediction or unexpected generation output. Here are some examples of different weekday demand patterns in Great Britain (GB).
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By Stephen Browning / Published on Wed, 2007-11-28 12:48
Each power system is always in balance; generation = demand. On an AC system, this rule is maintanied in real time by the frequency, whose deviation from nominal (50 or 60 Hz) represents the difference between 'required demand' and 'delivered demand'.
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By Hans De Keulenaer / Published on Sat, 2007-03-24 14:09
From ENTSOE comes a map of the European electricity system, indicating major power stations and transmission lines.
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