Electrical outages. cyber attacks ?

Kelly Marie:

I've just had a look at the dynamic demand site which has a live frequency meter I noticed the frequency was bouncing up and down very quickly  going from 49.8 to 50.08 cycles the bounce seemed very rapid and was happening for several minutes before stabilising a bit. Now I've not been able to look there for ages but I seem to remember from before that it didn't  change so rapidly is this some symptom of the recent bother They've had or is it normal  x Kelly

The rapid changes in frequency that you have observed are not a symptom of the recent failure, as I first observed such rapid and frequent changes some months ago.

They do however appear to be a relatively new phenomena which I find a bit worrying.

As has been suggested by others, the decline of conventional steam turbine driven alternators is a likely cause of this. A similar capacity of wind turbines and PV modules do not possess the mechanical inertia of steam driven plant. Neither is there the stored potential energy of the steam in the boiler.

I would however suggest an additional factor that is in my view contributing to these rapid changes, which appear to be verging upon oscillations at times.

Years ago we had a lot of manufacturing industry with machinery driven by induction motors. Any sudden drop in frequency will briefly reduce the energy absorbed by such motors, they might even very briefly generate electricity as they are driven by the mechanical inertia of the machine to which they are coupled. Any sudden increase in grid frequency will increase the energy absorbed by such motors as they "try" to accelerate the driven machinery up to the new synchronous speed, less a modest amount of slip. With less manufacturing industry, we have lost the inadvertent self stabilising effect of millions of induction motors.


Edit to add, I have previously posted about these rapid fluctuations in grid frequency. Cant remember if it was in the dying days of the old forum, or the early days of the new forum. Can anyone find a link ?

Kelly Marie:

I've just had a look at the dynamic demand site which has a live frequency meter I noticed the frequency was bouncing up and down very quickly  going from 49.8 to 50.08 cycles the bounce seemed very rapid and was happening for several minutes before stabilising a bit. Now I've not been able to look there for ages but I seem to remember from before that it didn't  change so rapidly is this some symptom of the recent bother They've had or is it normal  x Kelly

The rapid changes in frequency that you have observed are not a symptom of the recent failure, as I first observed such rapid and frequent changes some months ago.

They do however appear to be a relatively new phenomena which I find a bit worrying.

As has been suggested by others, the decline of conventional steam turbine driven alternators is a likely cause of this. A similar capacity of wind turbines and PV modules do not possess the mechanical inertia of steam driven plant. Neither is there the stored potential energy of the steam in the boiler.

I would however suggest an additional factor that is in my view contributing to these rapid changes, which appear to be verging upon oscillations at times.

Years ago we had a lot of manufacturing industry with machinery driven by induction motors. Any sudden drop in frequency will briefly reduce the energy absorbed by such motors, they might even very briefly generate electricity as they are driven by the mechanical inertia of the machine to which they are coupled. Any sudden increase in grid frequency will increase the energy absorbed by such motors as they "try" to accelerate the driven machinery up to the new synchronous speed, less a modest amount of slip. With less manufacturing industry, we have lost the inadvertent self stabilising effect of millions of induction motors.


Edit to add, I have previously posted about these rapid fluctuations in grid frequency. Cant remember if it was in the dying days of the old forum, or the early days of the new forum. Can anyone find a link ?