Thread by @emilygosden

National Grid will today submit its preliminary technical report to Ofgem on last Friday’s blackouts.

Here’s my exclusive in today’s @thetimes on what I understand to be its initial findings...

thetimes.co.uk/edition/news/l…

Key points: (🧵)

1) Both Hornsea offshore wind farm & Little Barford gas plant are believed to have failed within seconds of each other after a lightning strike to the grid near Little Barford. This caused disturbance that both should’ve been able to withstand; Hornsea had a “technical fault”
⚡️

2) These failures caused an unusually fast drop in frequency on the grid, resulting in a series of smaller “embedded” plants (wind/solar/diesel generators) automatically tripping off the system and exacerbating the supply shortage
📉

3) Supplies to parts of the local electricity distribution grids were then automatically cut to reduce demand and prevent the situation escalating into a wider blackout
🕯

4) Local electricity distribution networks cut power to a number of rail signalling stations, triggering chaos on the train networks
🚦

5) Trains operated by Govia Thameslink Railway shut themselves down in response to the drop in frequency on overhead lines. More than 20 could not be restarted as intended by drivers and had to have technicians sent out to fix them
🔧

All of which raises serious questions about the resilience of Britain’s energy & transport infrastructure.

National Grid won’t comment, Orsted says it’s fixed the Hornsea technical fault, Govia Thameslink has set up a task force to see what went wrong on its trains.

(End of 🧵)