High constraint cost expected to last until end March while Western Link remains out of action

The ‘Western link’ HVDC cable is likely to be out of action until the end of March, according to NGESO, adding millions of pounds of so-called ‘constraint’ costs because it will not be possible to export all the power from Scottish wind farms to customers in England and Wales. But it admitted that was its own assessment, not that of the link owner, SP Energy Networks.

Constraint costs, which represent one part of daily management costs, peaked as high as £10M  one day during the past week. The actual daily cost will depend on the weather, as windy conditions will increase the amount of power generated by Scottish turbines that has to be constrained, and for which turbine owners will be compensated. The system operator said power line ratings, which limit the power flowing through transmission cables to keep it within temperature limits, have been ‘enhanced’ to minimise to allow flow to be increased.

This week there have been additional constraint costs because of a separate onshore fault, but the onshore fault is expected to end next week.

Further reading

Longread: take a deep dive into offshore cable risks

NGESO ready to pay for ‘circuit breaker’ assets to reduce mounting constraint costs, BEIS considering options for long term storage


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