Ofgem to OFTO: check your settings before claiming an exceptional event

The owner of the link connecting Humber Gateway offshore wind farm will not get credit for two periods when it was out of service because the company should have checked the settings on its equipment, according to Ofgem.
So called OFTOs (offshore transmission owners) are paid according to availability of the link but receive credit if an ‘exceptional event’ takes it out of action. Humber Gateway OFTO claimed such events for brief periods April and September 2019 after lightning strikes hit NGET’s onshore network. It said the strikes wrongly tripped protection systems on its link and “if the relays had been commissioned with the correct protection settings the relays would have remained stable”.
It said the faults were outside its control because the relay settings were applied by the contractor during construction and could not reasonably have been discovered.
Ofgem said the lightning was “an expected event”. It said, “We expect licensees undertaking due diligence prior to purchasing the offshore transmission assets will check both the process (as the Licensee seems to have done) and the calculations (which the Licensee has failed to do) used in protection settings.” In its claim the OFTO said the full system study necessary to check and confirm that more than 30 protection relay settings was “a significant piece of work that has not been budgeted for”.
Ofgem was unimpressed with a claim that the September event was out of the OFTO’s control because an installation contractor based in Belgium took six months to correct the settings after the April event. It said, “It is our view that Licensees should ensure they have sufficient arrangements in place to respond quickly to incidents on the transmission system.”

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