1. © NERC All rights reserved The Space Weather Hazard to the UK Electricity Transmission System: A 2012 Update Alan Thomson, Ciarán Beggan, David Beamish, Gemma Kelly BGS Edinburgh www.geomag.bgs.ac.uk NASA/ISS

2. © NERC All rights reserved Supported by Scottish Power and ESA ‘Pilot Projects’ Updated every 10 minutes Time series displays for the 4 GIC measurement sites Animation of complete grid response to GIC Near real-time geomagnetic, solar wind monitors & geomagnetic forecasts 2006: Power Grid Analysis System Concept

3. © NERC All rights reserved Steps to ‘Second Generation’ UK GIC Model New ‘geological conductivity’ model of top 3km of crust GB wide model of 400, 275 and 132 kV transmission system Spherical elementary current system model of spatial and temporal geomagnetic variations across British Isles Extreme event scenarios Geo-electric field measurements E-field model validation Probing mantle conductivity (Irish transmission system)

4. © NERC All rights reserved UK airborne geophysical survey (fixed-wing) data acquiring high-resolution active frequency-domain EM and providing measurements of subsurface conductivity HiRES-1, no active EM 86 units New bedrock conductivity map Lithological classification of conductivity

5. © NERC All rights reserved AEM surveys covered 54 of the required 86 lithologies and provided 3 kHz conductivity estimates (best for bedrock) 32 missing, some very small areas The major 9 missing lithologies, are shown right Use natural lithological associations to provide conductivities for the missing 32 The distribution of the 32 unsampled lithologies.The 9 lithologies having total areas > 1000 km 2.shown in colour

6. © NERC All rights reserved

7. BGS2012 at 15:38, 15 th July 2012 BGS2012 – AMCK2002 LongLatNode NameAMK2002BGS2012 Absolute Difference -3.6723055.43700ELVA41-4.7-1.13.6 -2.6941054.02500QUER4A0.9-2.02.9 -3.4043050.77053EXET4113.710.82.9 -2.6941054.02500QUER4B1.2-1.62.8 -3.4025151.38554ABTH21-3.7-1.12.6 -3.9574851.68906SWAN2A10.88.32.5 -1.5328255.14180BLYT4B0.93.32.4 -2.4880950.62369CHIC42-4.9-2.62.3 -2.9631054.94179BEDD4B-2.6-4.62.0 -1.7437454.97754STWB4A-9.9-11.81.9

8. © NERC All rights reserved UK power network 2012 One transformer per node (simplified) One connection between linked nodes (simplified) Transformer and earthing resistances assumed identical across all transformers (simplified) Line resistances calculated using transmission line impedances provided by National Grid ~700 nodes ~1200 connections

9. © NERC All rights reserved No 132kVWith 132kV Adding the 132kV network Electrojet modelled as a tapered cosine with field strength 450nT and frequency 120s

10. © NERC All rights reserved GIC at some nodes reduced with 132kV included Significant GIC seen at some newly introduced nodes Adding the 132kV network

11. © NERC All rights reserved Differences between the networks at the 400kV and 275kV nodes Adding the 132kV network

12. © NERC All rights reserved Extreme Event: The ‘Halloween Storm’ x8

13. © NERC All rights reserved Geo-Electric Field Monitoring ADC & Data-logger Earthdata 24-bit ADC (150 dB @ 10 Hz) Raw sample rate: 192 kHz FIR & Linear phase response GPS time-stamped data Data output rate 50 Hz (test) Data units: µV/m Data-logger: BGS GDAS System Ground Electrodes LEMI 701 Low-drift (< 100 µV / year) Non-polarising Cu-CuSO4 chemistry Designed for long-term installation Submerged in Clay-CuSO4 solution Project Summary  Long-term measurements at: Eskdalemuir, Lerwick & Hartland  NS & EW electrode lines  Electrode line length: 50 – 100 m  Electrodes installed depth: 0.5–1.0 m  Monitoring period: 2 -5 years Pre-amplifier Low-noise differential amplifier High input impedance (> 4 MΩ) Selectable Gain: x2, x10, x100 < 50 µV RMS noise (all settings) Installation Status  First electrode pair (EW) installed at Eskdalemuir (12 September 2012)  Second electrode pair planned for Eskdalemuir in October 2012  Installations at Lerwick & Hartland planned for March 2013 Objectives  Comparison of measured and modelled data to aid numerical model developments  Longer term, project will provide magneto-telluric data for study of deep Earth conductivity

14. © NERC All rights reserved Irish grid model Inputs/Assumptions Major 400/275/220kV lines only But has extensive 110kV system 41 nodes / 57 connections Resistances: Earthing resistance: 0.1Ω Transformer resistance: 0.5Ω Line resistance calculated from All-Island Transmission Forecast Statement 2012-2018 All connections are straight lines Uniform earth conductivity model only

15. © NERC All rights reserved Example GIC – Halloween storm 2003 Snapshot during the storm Red circles indicate current flowing into the grid Blue circles indicate current into the ground

16. © NERC All rights reserved Future Upper mantle and crust conductivity models MT (and Swarm?) Add 132kV system for England and Wales Less extensive than Scotland Model Irish GIC Add 110kV system Validate electric field and GIC models with National Grid and Scottish Power GIC measurements Some Scottish GIC data available Detailed models of individual transformer electrical characteristics Beyond the common earthing resistances Within the FP7 EURISGIC project Re-examine extreme events Compare GIC for UK and Ireland (tests model assumptions)

17. © NERC All rights reserved

18. Acknowledgements EURISGIC colleagues (Extreme events and European grid development) Tom Shanahan, Chris Turbitt and Tony Swan (E- Field installation) National Grid (Chris Rogers, Andrew Richards) Scottish Power (Tom Cumming, Finlay Macleod) EirGrid (Robbie Aherne, Michael Kelly)