First reactive power contract awarded to offshore wind farm

National Grid Electricity System Operator (ESO) has awarded a ten-year contract to the Dogger Bank C offshore wind farm to provide reactive power absorption from its onshore converter station.

The contract was awarded as part of the Pennines Voltage Pathfinder – the second tender in its trial of a new voltage control service – which sought 700 mega-volt-amps of reactive power (MVAr) absorption to reduce voltages in the North East and West Yorkshire.

Julian Leslie, head of networks at the ESO, said: “These services take us another step closer to 100% zero carbon operation, showcasing Britain’s innovation in engineering and driving competition within the system, ultimately saving consumers millions of pounds.

“Reactive power capability is vital for managing voltage and being able to operate a zero-carbon system of the future so we’re excited to see that an offshore wind farm’s transmission asset will deliver reactive power to support the wider network for the first time in Britain.”

Dogger Bank C will receive an availability payment of £49.97 per settlement period to provide up to 200MVAr of reactive power absorption from its onshore converter station in the North East from April 2025.

The 1.2GW offshore wind farm is due to come online in 2026 after SSE Renewables and Equinor reached financial close on the project in December.

The ESO said this was the lowest-cost option to fulfil the requirement in the area, with an assessment price of £0.34/MVAr/settlement period. It calculated the total value of this option at just shy of £12 million.

Dogger Bank C will not receive payments for utilisation, although this will be limited to 11,000 settlement periods per year.

Steve Wilson, SSE Renewables project director for Dogger Bank Wind Farm, said: “Dogger Bank Wind Farm is continually pushing the boundaries of what can be achieved through the delivery of an offshore wind farm, breaking records and setting new milestones here in the UK and globally.

“Today’s announcement that Dogger Bank C will become the first UK offshore wind farm to use the functionality of its transmission assets to support National Grid ESO in balancing the network at the lowest cost is further proof of the outstanding innovation that our Dogger Bank team continually strives to deliver.

“It also demonstrates the significant positive impact that offshore wind energy, and Dogger Bank in particular, is having on delivering the UK’s net zero carbon electricity system while driving down long-term energy costs for British consumers.”

The ESO also accepted counterfactual proposals by National Grid Electricity Transmission (NGET) to install three shunt reactors to meet its requirement of 500MVAr of reactive power absorption in West Yorkshire.

Although NGET will not receive direct payment for providing the service, the ESO deemed the options worth £8.2 million, £8.3 million and £6.2 million as the cheapest on offer, with assessment prices of £0.23, £0.24 and £0.35/MVAr/settlement period respectively.

Lydia Ogilvie, director of network strategy and operations at NGET, said: “As agreed with the ESO and Ofgem we cannot bid into the pathfinder process in the way other market participants can. Our agreed role for this pathfinder has been to provide a baseline to enable the ESO to compare the economic benefits of a fixed-term contract to a long-term regulated asset solution.

“The analysis undertaken by ESO in this instance suggests that there is an economic case for NGET to develop 500 MVAr reactive capability in West Yorkshire.

“We will work with ESO and Ofgem to further understand the results and the consumer savings outlined and progress with the required projects to deliver the best outcomes for consumers.”