Hello everyone,
I’m studying electricity in school, but I still don’t have a firm grasp on electrical power systems and was hoping for some help. I have four main questions. Anyone working in power systems, please share your knowledge!
1. How do each of the various generation schemes (coal / steam turbine, wind farm, nuclear plants, etc) output power at exactly 60Hz? I understand the basics of how a electrical generator works, but I don’t understand how they stabilized the output frequency to exactly 60Hz.
2. How do multiple generation points in the system synchronize their outputs to each other? How do all the different power plants and such dump power onto the grid together at the same phase?
3. I guess I don’t understand the grid itself overly well. Could anyone explain the concept of the power grid? (for example, is it like multiple net contributors of power (power plants, etc) each acting similiar to batteries in parallel?
4. What happens to excess (unused) power? If a particular system has three 250MW power plants, but the neighborhoods they power only use up 600MW, what happens to the extra unused 150MW? I’ve heard that people monitor the power input/output and “adjust” the power output from the plants to match the consumers’ usage. Is this true, and if so, how is this done? (shutting off generators, running them more slowly, etc). Also, if this is the case, what is done for power generation sources that cannot be human controlled (say, a wind farm; when the wind blows, it turns)?
Thanks in advance.
One Response
the frequency 60 Hz is governed by the generator speed
and the number of poles in the design
60 Hz times 60 minutes = 3600 periods per minute
a 2 pole machine will rotate at 3600 RPM
a 4 pole machine = 1800 RPM and will be twice as difficult to revolve for the same power etc.
as for synchronization, it needs a master clock, usually obtained from a microwave link to the facility. this clock signal is used in a very similar way as an automobile cruise control system.
there is no excess power
as the load (demand) is increased the voltage drops
at a certain point another machine (generator) is put into operation
the effect is to boost the total network voltage
there is a certain tolerance (a certain amount of adjustment) on the voltage but it is not infinite
this is why you may sometimes notice lights come a bit brighter or dimmer.
it is that the utility company has switched some taps on transformers or switched machines ON or OFF
Anita