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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.analog
Subject: Re: Selling Energy to the Utilities
Message-ID: <5912@utzoo.UUCP>
Date: Tue, 27-Aug-85 11:54:43 EDT
Article-I.D.: utzoo.5912
Posted: Tue Aug 27 11:54:43 1985
Date-Received: Tue, 27-Aug-85 11:54:43 EDT
References: <288@ihnet.UUCP>
Organization: U of Toronto Zoology
Lines: 39

> ...I don't understand *how* you put power onto the grid.
> What is the mechanism?  If I drive a generator (e.g. wind powered),
> I would have to be damn careful, if I planned to simply plug the thing into
> the wall, wouldn't I?  Voltage sources in parallel have to be exactly equal,
> in phase and amplitude, else you produce a virtual short circuit.
> How does a homeowner do it?

Remember that most generators will also run as motors.  If your generator
is out of phase with the grid, the grid will drive your generator back
into sync.  Think of it as pushing on a crank attached to a huge, very
massive spinning flywheel -- you will add energy, but you will not change
the rotation rate noticeably, and either you start out in phase with it or
it will drag you into phase.  Of course, if you're too far off to begin
with, it may break your arms doing this, so it's advisable to get things
pretty close first.

The power company often also wants to install some sort of special gadget
at the interface, partly because when they take a power line down for
maintenance they want to make sure it is really 100% dead.

> How would they measure it, a separate meter?
> This seems necessary if they buy and sell at different rates.

Yup.  Although it may be possible to build a meter that would run at
different rates forward and backward.

> Sometimes the commercials talk about Com Ed's 6 generators,
> all running concurrently, to provide reliability.
> They *must* be (essentially) in parallel.
> How do you match phase and amplitude in all of them.

A combination of careful synchronization plus the generator-as-motor effect.

> When one fails, do circuit breakers take it out of the system?

Yup.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry