Lessons from the UK’s August 9 blackouts

An interim report is out from National Grid on the “Low Frequency Demand Disconnection” (LFDD) experienced in the UK on August 8th. There were a number of contributors to the LFDD. Instead of looking for a single culprit it would be better to list the contributors, because it’s the interaction that resulted in the event. I’ll review the failures in the UK to highlight a recent report from Ontario’s system operator (IESO) that has received too little attention.

Many suspected wind as the primary factor on August 9th, and the Hornsea offshore wind facility was heavily involved. So far that involvement has simply been identified as its failure to ride through a voltage dip caused by a lightening strike to transmission wires elsewhere.

From a useful infographic accompanying the report:

  • “There was a lightning strike on a transmission circuit north of London …”
  • “There was a small loss of embedded generation (c.500MW) due to the lightning strike. This is normal …”
  • Little Barford gas power station and Hornsea wind reduced supply to the grid by 1,378 MW

The last bullet point grabs the most attention, the first triggered the event despite being a common occurrence which was typically handled; but it is the middle point that should instigate changes in the operations of the grid.

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