Numerical investigation of an offshore vertical axis wind turbine farm : from the wind resource to the control and power generation

In order to fight climate change, renewable energy sources have become more and more attractive as part of the electrical energy mix of Europe. However, the existing technologies still need improvement in order to become competitive and phase fossil fuels out of the energy sector. In that regard, offshore wind has proven to be an interesting solution and still under-exploited resource. This study explores whether vertical axis wind turbines could be an attractive alternative compared to the existing offshore horizontal axis wind turbine farms, thanks to a reduced levelized cost of electricity. This study uses numerical simulations to provide a first assessment. In this technical investigation, the entire conversion chain is simulated from the wind resource to the electricity transmitted to the grid. One program simulates the mechanical behaviour of the wind turbine using the double multiple stream tubes model, another simulates the electrical power transformation and transport from the wind turbine to the grid. A one-way coupling is used between both programs in the form of a unique and common wind turbine speed controller. Finally, the coupling is tested on an offshore wind farm of 15 wind turbines of 5MW rated power each. The study demonstrates that DMST simulations do not provide reliable results for VAWTs. The electrical model proves to be robust and could be used for HAWT and VAWT farms. The coupling method is effective and proves to be at low computation cost.