Significant volumes of wind energy were constrained during an outage earlier this year on the Western Link HVDC connection in Scotland leading to record constraint costs, according to analysis by Cornwall Insight.
The research said the unplanned outage from 10 January to 8 February coincided with record-high levels of wind generation in the UK of 6.3 terrawatt-hours.
However, with 2.2GW of HVDC capacity unavailable, significant volumes of wind output had to be constrained, it added.
“Due to this, the cost of turning down wind output through the Balancing Mechanism hit a record high of £30.9m,” Cornwall Insight said.
Cornwall Insight analyst Lee Drummee said: “The Western Link was designed to accommodate the increasingly high volume of power generated in Scotland and prevent transmission bottlenecks. But since commissioning the cable has been fraught with issues.
“The availability of the link makes a clear difference. For example, December 2019 also saw high wind output of 5.6TWh.
“However, the Western Link was available in December, so, the volume of wind bids classified as system actions on the BM was significantly lower at 247.1GWh.
“Avoiding constraints not only allows more volumes of renewable power to flow onto the Grid but reduces the amount of money that National Grid has to pay to turn off wind farms in Scotland.
“However, the reliability of the Western Link will need to be solved for its full potential to be realised.
“As more onshore wind develops, especially in Scotland, the problems of constraints will need to continue to be actively managed.”