Re: Grand Apagon - Electricity (not) in Spain

On 30/04/2025 8:41 pm, Carlos E.R. wrote:

On 2025-04-30 11:59, 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.

 I understand that the turbine doesn't actually slow down, because the generator starts working as a synchronous motor drawing energy from the network instead; this is detected by the control system and feeds more water/gas/steam, etc.

It doesn't slow down much, but there's no such thing as instantaneous feedback - you have to an input change before you can start correcting the output.

As long as the network keeps the frequency.

The "network" can't keep the frequency - it's the corrections that keep the low term frequency stable

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 the stored mechanical energy in the spinning rotor can only get fed into the grid if the rotor slows down.
The generator has to have a control system to control the power being feed into the rotor to keep it spinning at the same speed while more energy is being extracted from it.
There's nothing magically stable about that kind of control system - it has to be designed to stable like any other feedback mechanism.
--
Bill Sloman, Sydney