Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: Grand Apagon - Electricity (not) in Spain
Date: Fri, 2 May 2025 03:41:46 +1000
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On 2/05/2025 2:21 am, Liz Tuddenham wrote:
> Bill Sloman <bill.sloman@ieee.org> wrote:
> 
>> On 30/04/2025 7:59 pm, Liz Tuddenham wrote:
>>> Bill Sloman <bill.sloman@ieee.org> wrote:
>>>
>>>> ... pumped hydro storage has the spinning
>>>> turbines, but grid scale batteries have invereters, which can reacta lot
>>>> faster than any spinning turbine,
>>>
>>> I thought the stabilising effect of a spinning turbine was because it
>>> *didn't* react quickly.
>>>
>>> The grid frequency begins to fall so energy from the moving parts is
>>> converted to electrical power which is fed into the grid to increase.
>>> the frequency.  This results in a loss of stored mechanical energy which
>>> causes the turbine to begin slowing down - which is detected by the
>>> control system and used to feed more water/gas/steam into the turbine so
>>> its speed is returned to normal.
>>>
>>> The interface between the stored mechanical energy and the electrical
>>> energy demand has an almost instant response and is inherently stable
>>> without needing elaborate control algorithms.
>>
>> But it isn't actually doing anything.
> 
> Yes it is, basic electrical engineering theory.
> 
> In effect it is a constant speed generator connected to variable load;
> increase the load and more electrical energy immediately flows into the
> load, taking mechanical energy from the inertia of the moving parts.
> They then begin to slow down and the much more heavily damped mechanical
> regulator feeds in more energy to them from the primary source.

So it is completely passive. A big battery isn't a primary source but it 
can provide enough DC current to let your grid scale inverter generate 
exactly the AC output that you need.

Why futz around with the rotating metal? It may entertain tourists, but 
that's really all that it is good for.

-- 
Bill Sloman, Sydney