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Post-Triad ‘darkest peaks’ and demand lows: National Grid’s 2017/18 winter

Image: Getty.

Image: Getty.

National Grid has provided insight on two new record-setting events during the 2017/18 winter period and how they impacted transmission system demand.

Earlier today National Grid launched its 2018 Winter Review and Consultation document, outlining its analysis of the supply and demand of power throughout the 2017/18 winter while requesting feedback from energy market stakeholders as it prepares for this year’s publication.

The system operator’s analysis of 2017/18 narrowed in on two particular record-setting events during last year’s winter period, chiefly the impact of the so-called ‘Beast from the East’ weather event in late February and early March.

During that cold snap transmission system demand peaked at 50.7GW. While that figure was within National Grid’s forecast, it came more than three months after it was expected to do so and, crucially, outside of the Triad period for last winter.

The first Triad period occurred on 11 December 2017 when demand reached 52.4GW. The third and final Triad period occurred on 26 February 2018 – the start of the cold snap – with demand reaching 50.5GW, however this was topped three days later when temperatures dipped to around -2 degrees Celsius. 

Image: National Grid.
Image: National Grid.

National Grid outlined the significance of this occurrence, referred to as ‘The Darkest Peak’, by stating that it was the first time it had occurred since records began in 1976/77.

It sparked greater strain and operational challenges on electricity networks as no Triad-related customer demand management was observed, which would have ordinarily helped reduce demand on the transmission system.

Essentially, National Grid said, while there was sufficient generation on the network to meet demand, the challenge was transferring that energy to where it was needed.

However the system operator experienced an altogether different challenge at the very start of the winter period when it oversaw the lowest overnight minimum demand recorded during Greenwich Mean Time.

On 29 October 2017, transmission system demand dipped to just 18.6GW, triggered by warmer than average temperatures and particularly high distribution connected wind generation.

But while National Grid described the two instances as challenging, it stressed that the electricity and gas system responded well.

Overall, weather corrected electricity demand stood at 127.8TWh in winter 2017/18, some 2.8% lower than the previous year owing to milder weather and continued increases in the amount of distributed generation. 


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