Re: Grand Apagon - Electricity (not) in Spain

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On 4/30/25 4:08 AM, Liz Tuddenham wrote:

Carlos E.R. <robin_listas@es.invalid> 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.

 That doesn't sound right to me.  If the frequency of the grid is
dropping and the turbine is running at the correct speed, the mechanical
energy will flow into the grid as electrical energy and the speed will
start to drop  ... but the speed can never drop below the grid frequency
because when the energy flow from the turbine stops there is no longer
any load on the turbine and it doesn't slow down any further.
 If the turbine lost its source of mechanical power, then it would
'motor' and extract energy from the grid - but reverse current detectors
would promptly disconnect it.
 

The phase angle of the power generated/consumed will change. The actual speed will not change (although strictly speaking there will be a finite rate of change of speed to accomodate the change in phase angle).