There have been no constraint payments to Scottish wind power in the UK’s Balancing Mechanism (BM) since the 21st of April and up to the date of writing (7th of May). This is welcome after a very expensive start to the year when consumers paid £95 million to discard Scottish wind output from the 1st of January to the 21st of April..
But the reduction in constraints is not the result of improved balancing techniques or the return to service of the hitherto troubled Western Link interconnector. Rather, it is the result of low wind generation in Scotland reducing congestion within the country and over the links to England. Consequently exports to England have been declining for some weeks.
The figure below graphs average daily transfers of electricity (MW) across the Anglo-Scottish interconnectors, as reported by National Grid and archived by REF.
Figure 1: Average daily electricity transfers (MW) across the Anglo-Scottish interconnectors in 2020 to date (blue line), with a running seven day average of the averages (red line). Gaps in the chart occur when a complete set of daily data was not available or obtained. Source: Chart by REF: Data from National Grid.
UK wind output was high in the months of January (6.3 TWh) and February (6.9 TWh), fell back in March (5.6 TWh), and slumped in April, when it generated only 3.4 TWh. So far, wind output in May is also low. Indeed, Scotland is now frequently importing electricity, even at this time of extremely low load in the GB system.