For the first time in Britain, a transmission asset primarily intended for an offshore wind farm is also to be employed to produce reactive power to provide grid support to the wider network.
As part of the NG ESO’s £24.5 million ‘Pennines Voltage Pathfinder’, the Dogger Bank C onshore HVDC converter station at Lazenby, together with shunt reactors to be installed by NGET at HV substations, will between them provide 700 MVAr of reactive power capability in North East England and West Yorkshire over the period 2024 to 2034.
The Voltage Pathfinder “identified two areas where reactive power solutions would be needed in the years ahead and introduced competition to ensure the most cost-effective services were selected”, says NG ESO (National Grid Electricity System Operator).
In North East England, Dogger Bank C wind farm’s planned Lazenby converter station – on which construction is due to start this summer – will provide 200 MVAr over the ten year period under a reactive power tender won from NG ESO.
This is intended to help stabilise voltage on the grid after the expected closure of Hartlepool nuclear power station in March 2024.
An added benefit of making use of the functionality of an offshore wind transmission asset for grid support is reducing the need for construction of additional energy infrastructure in the region, lessening visual impact on coastal communities (in line with the UK’s Offshore Transmission Network Review).
In West Yorkshire, the Pathfinder process “found that the counterfactual submitted by NGET [National Grid Electricity Transmission, the transmission system owner] was the most economic option for the ESO to manage voltage in the best interests of consumers”, with delivery of shunt reactors compensating for loss of reactive power due to closure of other power stations in the area.
As part of introducing greater competition onto the network, an aim of the Pennines Voltage Pathfinder was “to compare market-based solutions against transmission owner solutions.” The NGET offering is described as “counterfactual” because under agreements made with ESO and regulator Ofgem it “cannot bid into the Pathfinder process in the way other market participants can”, said Lydia Ogilvie, NGET’s director of network strategy and operations. “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.”