Justin Richards wrote:
> The question has come up regarding syncronising hyrdoelectric power stati=
ons.
>
> I can see how a diesel fired station is controlled but I cant see how
> you could control a hydro powered turbine.
Are we talking conventional dam based hydro or "run of the river" hydro=20
here?

To sync a generator to a grid you need way of varying the rotation speed.

In a conventional hydro plant with a dam and a turbine in a tunnel you=20
would do this by adjusting the valve that feeds water down the tunnel to=20
the turbine just as you would adjust the throttle on a fossil fuel=20
powered engine.

In a "run of the river" plant things are trickier, if you wanted speed=20
control you would probablly have to either have some kind of brake on=20
the shaft or some way of feathering the blade. I suspect many of them=20
aren't synced at all and use electronic approaches to get power to the=20
grid but I dunno for sure.

There are various ways to tell if you are synchronised, a crude but=20
simple method that works for small generators is to connect three lamps=20
between the outputs of your generator and the grid. When all three lamps=20
go off then you are syncronised. Bigger and/or better generators=20
presumablly have something to measure the phase directly.

Once the switch is thrown the electromagnetics take over the=20
synchronisation. The generators try to push the frequency up, the loads=20
try to drag it down and a balance is reached. Someone (or something) in=20
a central control room adjusts the total power generated and hence the=20
overall frequency that the grid runs  at.

> I guess they generate ac and variable freq convert to dc and convert to a=
c.'
>
>
> However, the converts would have to handle a huge amount of power and
> perhaps not possible to build such a device.
>
> Any ideas.
>
> The web didn't want to play.
>
> Cheers Justin
>  =20

--=20
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