Mains Syncronisation

[horaceg]

Hi Guys,
Can anyone please point me in the right direction to a Web-Page or Site that explains, simply, how Mains Voltage & Current generated from, say, a Wind Generator, links into household mains and suppliments the supply?
Thanks in advance.
HoraceG

 

[slippyr4]

The small scale wind generators i've seen don't supplement the existing mains - there is either a changeover switch or more often a single circuit is powered from the wind.

 

[sm1thson]

the B&Q wind turbine claims to:

The Windsave wind turbine delivers up to 1KW of supplementary energy synchronised and adjusted to supply directly into your household power circuits, using Windsaves unique technology the appliances in the house will absorb all the energy from the turbine before using grid voltage

but I'm sorry i dont know how it does it, thebig control box connects to the ring via a FCU!

I am also interested in the workings behind it.

 

[davelx]

When I was at Uni it was just a matter of connecting 3 lamps across the 3 switches linking the 3 phases of the mains to the generator and adjusting the generator excitation and load with the switches open so that the phase slip was slow enough to see and then when all the lamps went out we just hit the switch that linked the gene to the mains - this locked the gene to the mains, and then we turned up the exitation to push power into the grid.

(Standard experiment in 1st year elec eng course)

I expect a similar but automated technique would not be hard to implement using micro-controllers.

 

[JohnD]

I don't know how the B&Q one works, but, with real generators, the way they keep in synch is that a generator is the same as an electric motor. If you connect it to supply without driving it, it will spin up to speed driven by the grid. If you try to make it go faster, it could only do that by providing enough power to speed up all the other generators on the grid (which it can't). If you try to make it go slower, it could only do that by slowing down all the others.

Before connecting, you spin it up to speed and synchronise it with a simple instrument (it can be done with three light bulbs). Otherwise there will be an immediate acceleration or deceleration when it goes on supply.

There is a story told in the industry of a generator that was put on supply without being synchronised; it ripped its mountings out of its concrete bed, jumped in the air and rolled across the hall floor. No-one seems to know if the story is true.

 

[horaceg]

Thanks for the replies.
If I've got this right, and once the generator is syncronised, the appliances in the installation will draw their required current from the generator first and THEN suppliment any additional load required from the Mains via the Meter?
So, in theory, if the generator were capable of supplying all the load requirement of the installation then no current would be consumed from the mains and therefore no meter reading.
What would happen then, if the generator were capable of supplying a greater load than was required from the installation? Would the extra load go the 'other way' and run the meter backwards?
Interesting!
HoraceG

 

[slippyr4]

but could you do it properly with only one phase?

if you had a big turbine on a windy day and were exceeding your home's demand, then you'd be pushing power into the grid - but only one phase of it. surely the DNO wouldn't like that for phase balancing reasons?

 

[JohnD]

I see the thing only produces 1kW under the right conditions, I doubt the DNO would even notice it.

 

[slippyr4]

what about your meter? which way would it turn with current going the wrong way?

 

[horaceg]

Ah well now,
In the bad ol' days, if you swopped the tails in the meter i.e. incoming in the right hand side and load into the lHS then the meter used to run backwards!
Not that I've ever actually done this you understand.
I don't know about contempory meters though.

 

[JohnD]

I heard that the old type with a spinning disk could be made to go backwards, I doubt the modern digital ones do.