Measuring and modelling the power curve of a commercial-scale tidal turbine

The power curve is presented for Alstom Ocean Energy’s 1 MW tidal turbine over a series of deployments at the European Marine Energy Centre in Orkney. The power curve’s underlying velocities were measured via four-beam seabed-mounted Acoustic Doppler Profilers (ADP) and a single-beam ADP (SBD) mounted on the turbine nose and pointing into the flow. Seabed ADPs were positioned upstream of the rotor plane at ranges informed by IEC 62600-200 standards. The power curve is shown to have a slight sensitivity to ADP position at these ranges, with slower flow measured closer to the turbine which leads to apparent increase in power. A larger sensitivity to the power curve is observed between the flood and ebb tides where the shear profile and ambient turbulence levels are different. The SBD under the existing configuration is shown to be inadequate for measuring ambient flow due to its restricted beam range. Finally the results are compared with dynamic and steady numerical predictions obtained with a Blade Element Momentum code, Tidal Bladed. The steady calculation is unable to sufficiently predict measured results due to neglecting transients in the flow whereas the dynamic curves show good agreement.