UK Project Explores Increasing Array Cable Voltage

The Carbon Trust has launched a project to build industry consensus on setting the future standard array cable voltage for offshore wind farms.

The High Voltage Array Systems (Hi-VAS) project is the latest joint industry initiative under the Offshore Wind Accelerator (OWA) programme.

It aims to understand the costs, benefits and technology challenges associated with raising the array voltage.

The wider consortium of the Hi-VAS project consists of seven wind farm developers, EnBW, Equinor, Orsted, RWE, ScottishPower Renewables, Shell and Vattenfall.

The £500,000 project is set to run until January 2022 and is being delivered by the Carbon Trust, TNEI and Petrofac.

It builds on the success of previous OWA work in raising the array voltage from 33kV to 66kV, where similar industry consensus was reached five years ago.

As offshore wind turbines are set to grow beyond 15MW, it is widely agreed within the industry that the current standard array voltage of 66kV will be insufficient.

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.

The Carbon Trust said 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.

In time, the array system supply chain could gradually accommodate the next generation of turbines a collaborative approach is seen as a way to “accelerate this transition to ensure the industry can continue to reduce costs and increase capacity”.

The technical and regulatory changes required when raising the array voltage will be examined.

Detailed cost-benefit analysis, risk analysis and preliminary design studies will be performed for a range of possible future array voltages and a range of future turbine sizes (14-20MW) to identify the next optimum array voltage.

Carbon Trust offshore wind director Jan Matthiesen said: “Offshore wind is a leading solution to tackle climate change globally and we must continue to innovate to accelerate and optimise deployment.

“By demonstrating a strong alignment among developers a clear and consistent message can be sent to the supply chain, which will ultimately accelerate the introduction of high voltage array systems and hence the next generation of wind turbines.”