New project looking to raise OWF array voltage beyond 66 kV

A new joint industry project has been launched as part of the Offshore Wind Accelerator (OWA) programme with an aim to build industry consensus on setting the future standard array voltage for offshore wind farms.

The High Voltage Array Systems (Hi-VAS) project aims to understand the costs, benefits and technology challenges associated with raising the array voltage as the output of offshore wind turbines will increase beyond 15 MW and the current standard array voltage of 66 kV will become insufficient.

Hi-VAS is being delivered by the Carbon Trust, TNEI and Petrofac, in cooperation with seven offshore wind farm developers: EnBW, Equinor, Ørsted, RWE, ScottishPower Renewables, Shell and Vattenfall.

The GBP 500,000 initiative, set to run until January 2022, builds on the previous OWA work on raising the array voltage from 33 kV to 66 kV, where similar industry consensus was reached five years ago, the Carbon Trust said.

“A higher array voltage will be necessary to enable cost-effective string lengths and layout designs; reduce electrical losses; and ultimately enable the deployment of larger turbines. However, uncertainty remains as to what the optimum next array voltage is; the appropriate timing for making the change to the next array voltage; and the most efficient path to the next array voltage in terms of technology and regulatory development”, the Carbon Trust said.

“Whilst, in time, the array system supply chain could gradually accommodate the next generation of turbines and regulators would progressively move to accommodate changes in array system technology; a collaborative approach will accelerate this transition to ensure the industry can continue to reduce costs and increase capacity”.

The Hi-VAS project aims to achieve this by engaging supply chain and regulatory stakeholders to provide insights into the practical challenges faced in raising the voltage, as well as to provide constructive criticism and to ensure the project’s findings are supported and acted on by the industry.

The project will examine the technical and regulatory changes required when raising the array voltage and perform detailed cost-benefit analysis, risk analysis and preliminary design studies for a range of possible future array voltages and a range of future turbine sizes (14-20 MW) to identify the next optimum array voltage.

Furthermore, Hi-VAS will carry out a series of engineering design studies examining how each component, standard, method, or regulation associated with the array system may need to adapt.

Recommendations on how to address barriers identified though the project will be included in an industry roadmap to ensure the recommendations are taken up by the supply chain and regulators, the Carbon Trust said.