The system could also reduce maintenance costs by 3 per cent. The technology was tested on five wind turbines at ECN’s wind farm test site and the centre now plans to test the technology on a larger scale at an offshore wind farm.
The system is based on better turbine positioning, which can reduce the wake effects of turbulence. In a perfect line position, turbines produce 100 per cent power, but also take a 100 per cent load on axes and blades. When placed behind each other, the upstream turbine still produces 100 per cent power, but the capacity of the downstream turbines is reduced to 60 or 50 per cent. On top of this, wake effects caused by turbulence increase their load to 110 or 115 per cent and maintenance costs rise proportionally.
By changing the pitch angle and/or the yaw angle of the front turbine a few degrees, the turbulence is deflected/altered, thus reducing the load and increasing the power production of downstream turbines.
ECN first used in-house developed simulation tools to test the active wake control system, followed by a full-scale test on five 2.5 Megawatt Nordex turbines and on a scaled wind farm with ten 10KW turbines at its test site in the Wieringermeer in the Netherlands. All tests reportedly showed that the wind farm’s power production was increased by 0.5 to 5 per cent and the loads were significantly reduced.