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From: Martin Brown <'''newspam'''@nonad.co.uk>
Newsgroups: sci.electronics.design
Subject: Re: The Spanish Grid Drop-out - recently released information.
Date: Mon, 12 May 2025 22:47:14 +0100
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On 12/05/2025 18:35, john larkin wrote:
> On Sun, 11 May 2025 12:22:11 +1000, Chris Jones
> <lugnut808@spam.yahoo.com> wrote:
> 
>> On 11/05/2025 5:04 am, john larkin wrote:
>>
>>> As solar and wind get to be dominant, micromanagement of power sources
>>> and loads will be necessary to ensure uptime.

It only requires that enough of the larger more powerful systems 
cooperate and that automatic load shedding occurs fast enough and with 
the right amount to prevent cascade network failure when things go bad. 
Spain seems to have got the latter catastrophically wrong.

UK wasn't too good in 2019 either.

>> This is largely unnecessary - if the control signal that was being sent
>> out by the central controller to micromanage each power source was
>> derived from a function of the frequency, phase, voltage etc., then
>> rather than trying to distribute the result of this calculation to
>> millions of devices with low latency, it is better to distribute just
>> the formula (once every few years or as necessary), and run it on a
>> microcontroller in the inverters several times every mains cycle. They
>> already have more than enough processing power.

They are all connected to the national grid. The grid frequency target 
and voltage is extremely well known and all that is needed is for each 
unit that can to try and drive the grid voltage and frequency towards 
that target. Things get iffy when they drop out a lot of stuff all at 
once because they are using the same rules and rapid collapse follows.

> A central (international!) controller would want to know what every
> contributor was pushing into the grid, and probably see wind flow and
> clouds moving around. One local transmission line could fail and take
> down half of Europe. Again.

The big fat controller is already needed for any national grid. The UK 
once made the mistake of letting BBC TV into the main National Grid 
control room live in the late 60's and the interviewer asked innocently 
if the live displays meant that if everyone watching switched on their 
kettle the needle would shift. An edict went out afterwards to the 
effect of never again will any live broadcast team be allowed on site.

https://www.bbc.co.uk/programmes/b00vkjmy

Unfortunately the series where it is mentioned is no longer available to 
stream.

>> The rapid control algorithms should be distributed, and the only
>> low-latency communication signals they should rely upon are frequency
>> and voltage.

The whole thing seems to be messy with the domestic ones made down to a 
price being rather less able to cope with surprises. Only some of the 
BESS systems are configured for frequency stabilisation. Their main 
objective is to make money for their investors by time shifting power.

> A solar panel with an algorithm can't now about potential system
> overloads. Solar and wind will have to be shed sometimes to protect
> the entire system. Loads shed too. Renewable-heavy grids are fragile.

It can sense if the voltage and/or frequency is too high or too low and 
if it has output margin available act to counter it. This is only really 
worthwhile if it has some stored battery energy reserve to draw upon. 
The grid being overloaded is more common than over supplied (and there 
are consumers of last resort that can load balance to some extent).

Wind power scaling as cube of windspeed means that quite often wind 
Scottish wind farms are paid to feather their turbine blades because the 
cables are far too feeble to carry the power away.

Big problem in daytime is that most of the BESS systems are running flat 
out supplying power to industry and consumers so that they don't have a 
lot of reserve to offer if things start to go wrong. Likewise when a 
failure happens in the early evening peak consumption 6pm-8pm.

Peak demand premium pricing means they all want a slice of that cake.

-- 
Martin Brown