Electrical outages. cyber attacks ?

National Grid have released their interim report. I've attached it

Thanks for hat Jam - it's an interesting read.


So in short a lightning strike on a distribution line had three effects:

1. Tripped out the protection for that line (as intended), losing both loads and embedded generation in the area served, then the protection autoreclosed within 20s restoring the loads, but embedded generation has to wait longer before it's allowed to reconnect - so the load on the national grid increased by the amount of the embedded generation (500MW they say).

2. The spikes from the strike also caused two of the three interconnectors from a wind farm to trip out (not expected) - losing 737MW

3. The spikes from the strike also caused one steam turbine at Barford Gas Power Station to trip out (not expected) - losing 244MW


The loss of the steam turbine knocked the combined cycle system out of kilter, so causing the two associated gas turbines to trip out within 90s - losing a further 397MW


So the grid was then out of balance to the tune of 1.9GW - while the grid has 'reserves' ready for only 1.0GW - enough to compensate for the loss the largest single generator - so the DNO's systems started load shedding.


(Is it just me or does 500MW of embedded generation on one single distribution line sound like a lot - especially at that time of day when solar would have been very much in decline? I wonder if Mike's point about modern electronic (VF drives etc) loads increasing demand in response to low voltage - unlike old fashioned star/delta induction motors that would probably act as mini generators for a while - might have accounted for some of that figure)


Maybe we just need a few more SPDs?


   - Andy.

National Grid have released their interim report. I've attached it

Thanks for hat Jam - it's an interesting read.


So in short a lightning strike on a distribution line had three effects:

1. Tripped out the protection for that line (as intended), losing both loads and embedded generation in the area served, then the protection autoreclosed within 20s restoring the loads, but embedded generation has to wait longer before it's allowed to reconnect - so the load on the national grid increased by the amount of the embedded generation (500MW they say).

2. The spikes from the strike also caused two of the three interconnectors from a wind farm to trip out (not expected) - losing 737MW

3. The spikes from the strike also caused one steam turbine at Barford Gas Power Station to trip out (not expected) - losing 244MW


The loss of the steam turbine knocked the combined cycle system out of kilter, so causing the two associated gas turbines to trip out within 90s - losing a further 397MW


So the grid was then out of balance to the tune of 1.9GW - while the grid has 'reserves' ready for only 1.0GW - enough to compensate for the loss the largest single generator - so the DNO's systems started load shedding.


(Is it just me or does 500MW of embedded generation on one single distribution line sound like a lot - especially at that time of day when solar would have been very much in decline? I wonder if Mike's point about modern electronic (VF drives etc) loads increasing demand in response to low voltage - unlike old fashioned star/delta induction motors that would probably act as mini generators for a while - might have accounted for some of that figure)


Maybe we just need a few more SPDs?


   - Andy.