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From: piglet <erichpwagner@hotmail.com>
Newsgroups: sci.electronics.design
Subject: Re: Grand Apagon - Electricity (not) in Spain
Date: Thu, 1 May 2025 21:50:45 -0000 (UTC)
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Jeroen Belleman <jeroen@nospam.please> wrote:
> On 5/1/25 12:04, Martin Brown wrote:
>> On 01/05/2025 01:36, Chris Jones wrote:
>>> On 30/04/2025 1:07 am, Martin Brown wrote:
>>>>> The idea that renewable sources make the grid frequency harder to 
>>>>> manage sounds like total nonsense.
>>>> 
>>>> It is pretty much accurate. The local feed in for domestic PV track 
>>>> whatever frequency they see on the network. The big problem is that 
>>>> without the large spinning generators and the energy stored in that 
>>>> angular momentum the frequency is able to shift rather too quickly.
>>> 
>>> If the specifications for the inverters are written based on sound 
>>> engineering and simulation of the grid behaviour rather than fear and 
>>> ideology, it would be quite feasible to alter the algorithm in the PV 
>>> inverters to help stabilise the grid frequency. For example, you could 
>>> make it simulate what a spinning generator would do, or very likely 
>>> something much better.
>> 
>> I don't disagree that inverters at least on the bigger systems could be 
>> made to behave a lot more like a system that has physical inertia.
>> 
>> I don't think it is viable for home units though since they are made 
>> down to a price and the robustness needed to oppose a frequency drift is 
>> not insignificant. They would be like a flea trying stop an elephant.
> 
> I don't agree here. Since the power injected into the grid by
> large installations is regulated by looking at the frequency,
> once the grid gets dominated by, say, solar PV power, they'd
> better make sure it behaves the same way. Of course, any single
> small unit can't have a noticable effect, but collectively,
> they can!
> 
> Jeroen Belleman
> 

It looks like most European inverter specs call for disconnect at 47Hz
immediately and 47.5Hz within some tens of seconds but older models had to
disconnect if the rate of change exceeded 0.2Hz/s but in an effort to
improve stability newer requirements are to tolerate rate of change up to
2Hz per second. Perhaps Spain has a large number of older spec inverters?

This document goes into more detail:


https://eepublicdownloads.entsoe.eu/clean-documents/SOC%20documents/Inertia%20and%20RoCoF_v17_clean.pdf

-- 
piglet