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From: "Carlos E.R." <robin_listas@es.invalid>
Newsgroups: sci.electronics.design
Subject: Re: The Physics Behind the Spanish Blackout
Date: Thu, 12 Jun 2025 10:31:35 +0200
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In-Reply-To: <102cuma$1umr0$1@paganini.bofh.team>

On 2025-06-12 00:07, Waldek Hebisch wrote:
> Carlos E.R. <robin_listas@es.invalid> wrote:
>> On 2025-06-10 12:08, Liz Tuddenham wrote:
>>> Carlos E.R. <robin_listas@es.invalid> wrote:
>>>
>>> [...]
>>>>>>>>
>>>>>>>> Solar and wind can be made to impose a gigantic inertia with
>>>>>>>> appropriate
>>>>>>>> electronics. You can fixate the output at 50Hz, locked no matter what.
>>>>>>>
>>>>>>> Only if the surplus energy is available to supply the necessary current.
>>>>>>
>>>>>> Not needed.
>>>>>>
>>>>>
>>>>> Why not?
>>>>
>>>> Think about it. Inverters can be locked in frequency to any timing
>>>> source.
>>>
>>> If the source (grid) starts to fall in frequency the inverter will
>>> either have to keep in step with it or supply massive currents as the
>>> phase difference between the inverter and the grid begins to increase.
>>> If the inverter tries to stay on-frequency, the time will come when they
>>> are 180-degrees out of step, then things will get far too exciting.
>>
>> Sure, same as any rotating mass that tries to oppose the drift. The
>> thing is, inverters have more "inertia" than rotating masses with a
>> turbine of the same power, if so configured or programmed to do.
>> Aggregating all of them, that's a huge inertia, way larger than rotating
>> masses.
>>
>> Say, program to oppose 1% the drift. Whatever. There are engineers that
>> can study and decide what to do.
> 
> I think that you ignore main aspect of inertia.  You have a power
> deficit and you need to adjust grid to compensate for lack of
> power.  Inertia means stored energy which can be deliverd at
> cost of lowering frequency.  IIUC in grid with rotating generators
> and with similar deficit like in Spain it is supposed to give you
> grace period of about minute or maybe 2 minutes.  In this time
> control may try to activate new sources or start controlled
> dropping of loads.  Current reporting indicate that inertia
> in Spain was enough for 20 seconds and that was too little for
> orderly reaction.
> 
> Sure, inverters can try to keep fixed frequency, but then
> instead of too low frequency problem you get too low voltage
> problem.  IIUC low voltage could lead to shutdown of the grid
> in a fraction of second.
> 
>> I can only say, if the cause of the Gran Apagón is found eventually to
>> be the lack of inertia in wind and solar generators, it is just a matter
>> of reprogramming the inverters or replacing them. An engineering and
>> economics problem, not a political one.
> 
> You can try to improve control algorithms so that they cope
> better with short term power deficit.  Given scale of deficit
> and observed result there may be space for improvement there.
> But logically, you need some fast reaction energy storage.
> Or some instantly swichable generating capacity.  But running
> PV sources (or other) at say 80% of their true power (so that
> you can instantly increase their output) looks rather unattractive
> compared to energy storage.  You can use rotating masses,
> for example run traditinal generator powering it from the grid to
> keep it moving (so it does not need a turbine) or grid scale
> battery.  Fast reaction energy store give you time to
> activate slower sources like hydro or fast start gas powered
> generators.  Or to drop loads in controlled way.
> 
> The point is that if you have power deficit, then grid can not
> work well.  And without energy storage you may lack time to
> switch on extra generating power (assuming that it is available).
> Instantly dropping loads may be possible, but if it is the
> only short term balancing mechanizm, then effect on loads may
> be nasty.

Ok, so authorities will have to push to build energy storage fast.

-- 
Cheers, Carlos.