Re: Grand Apagon - Electricity (not) in Spain

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.

There is nothing magic about the current from a rotating generator that cannot be exactly replicated by an inverter that synthesises the same waveform and produces it with power semiconductors instead of a steam engine. Especially domestic single-phase inverters already incorporate enough capacitance to buffer the PV energy supplied to them, so as to supply a sinusoidal current to the grid, and this storage allows it to shift the phase of the current relative to the voltage however required in order to help stabilise the system, if only it were allowed to and required to by regulations.

The load is very stiff though so only the biggest inverters can hope to fight it and survive. AFAICS the electronics should be able to track frequency OK. Transformers tend to object if the frequency gets too low.
All bets are off once the magnetic core saturates.
--
Martin Brown