Electrical outages. cyber attacks ?

John Russell:

Jam:

National Grid have released their interim report. I've attached it but you can also download from National Grid's website The magnitudes are exceedingly similar to the event in 2008 I mentioned before. The frequency plot does suggest rapid swings in frequency at the time of the event but while some local generation was lost due to the HV earth fault, most of the connected embedded generation stayed connected, suggesting that the ROCOF was within acceptable limits; most of the generation that was lost was as a result of issues within the plants themselves (some which have yet to be explained). The load shedding occurred 85 seconds after the event, while frequency response services (including batteries contracted for this very purpose) went from 0 to 650MW in less than 10 seconds... The story is not so much about inertia as it is an imbalance in supply and demand due to the sudden loss of supply.

I'm not sure I agree with your take on the report.  The report states that 500MW of embedded generation at the distribution level was tripped by Loss of Mains protection.  That 500MW is a substantial part of the generation shortfall.  The most common Loss of Mains protection is RoCoF protection and most of it would have been set to trip at 0.125Hz/s under the G59 regime.  The revised G99 regime increases the trip setting for plant commissioned after May this year.  Maybe that change in setting should also be required retrospectively for plants commissioned before this year.

John Russell:

Jam:

National Grid have released their interim report. I've attached it but you can also download from National Grid's website The magnitudes are exceedingly similar to the event in 2008 I mentioned before. The frequency plot does suggest rapid swings in frequency at the time of the event but while some local generation was lost due to the HV earth fault, most of the connected embedded generation stayed connected, suggesting that the ROCOF was within acceptable limits; most of the generation that was lost was as a result of issues within the plants themselves (some which have yet to be explained). The load shedding occurred 85 seconds after the event, while frequency response services (including batteries contracted for this very purpose) went from 0 to 650MW in less than 10 seconds... The story is not so much about inertia as it is an imbalance in supply and demand due to the sudden loss of supply.

I'm not sure I agree with your take on the report.  The report states that 500MW of embedded generation at the distribution level was tripped by Loss of Mains protection.  That 500MW is a substantial part of the generation shortfall.  The most common Loss of Mains protection is RoCoF protection and most of it would have been set to trip at 0.125Hz/s under the G59 regime.  The revised G99 regime increases the trip setting for plant commissioned after May this year.  Maybe that change in setting should also be required retrospectively for plants commissioned before this year.