OFFICIAL
Ref. Ares(2021)4296942 - 01/07/2021
GB SECURITY OF ELECTRICITY SUPPLY Winter 2017/18
OFFICIAL
Winter Outlook 2017/18
De-rated margin of 6.2GW
Total maximum technical
generation capability:
102.2GW
= 10.3% (Underlying
demand)
= 11.5% (Transmission
demand)
Forecast Peak Demand
=
62.3GW (including
assumed 900MW operating
Includes. 2.4GW
reserve)
interconnector net imports
De-rated generation
capacity:
Equates to loss of load
66.1GW
expectation (LOLE) of 0.01hr
per year (against a standard
of 3hrs per year)
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OFFICIAL
Comparison with 2016/17
Margins
• 17/18 de-rated margin = 11.5% (transmission demand basis)
• 16/17 de-rated margin = 6.6%
Loss of Load Expectation (LOLE) – standard = 3hrs per year
• 17/18 = 0.01hr per year
• 16/17 = 0.5hr per year
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OFFICIAL
Capacity Market
•
2017/18 is first delivery year of the Capacity Market
•
Bulk of capacity secured up to 2020/21 so far (auction for 2021/22 takes
place in Feb)
• Capacity Market provides regular payments to capacity providers in return for
being available to produce energy (or reduce demand) when the system is tight
• Capacity secured through auctions held 4 years and 1 year ahead of delivery
• Penalties apply for failure to deliver
• Forecasts based purely on the level of capacity secured through the CM auction
give a margin of 6.6% (TD basis), similar to the last two winters
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OFFICIAL
National Grid Tools
•
Capacity Market Notices (CMN) – Automatic notice to the market (especially
CM participants) to be alert to the potential for system notifications. Issued four
hours ahead of time when margin is forecast to drop to 500 MW or less above
operational margin.
Not a call to bring forward additional capacity.
•
Reserves – Range of small scale reserves (e.g. Short Term Operating Reserve)
that can be utilised in certain circumstances.
•
Electricity Margin Notice (EMN) – Call for additional generation and demand
turn-down to restore margins to operational margin levels of approx. Issued at
NG discretion but rough trigger point approx. 500MW below the operational
margin.
•
Voltage control – Slight reduction in voltage output to “stretch” available
capacity. Low impact on consumers.
•
Maximum Generation – Short term instruction to generators to operate at
maximum output.
•
Emergency interconnector assistance – call for extra interconnector flows
from continent (governed through bilateral agreements)
•
Controlled Disconnections
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OFFICIAL
Illustrative response process
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OFFICIAL
So far this winter …
• Electricity margins have been consistently adequate
or better
• As a result there has been no requirement to use
the Capacity Market (CM) reserve so far this winter
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