Until now, no pan-European nor worldwide consensus on appropriate test methodologies and practices have yet been implemented in order to carry out standard laboratory tests. For performance test (in laboratory as well as in-situ), the measurement of the upstream flow velocity is required to calculate kinetic energy, especially when the turbulence intensity is high. These flow fluctuations affect significantly the performance and fatigue behaviour of tidal turbines. However, for a good accuracy the upstream flow measurement needs to be performed in a synchronous way with the turbine parameters. In this paper, we study the time and space correlation between velocity measurements and turbine parameters in order to evaluate and improve the specifications given in IEC TS 62600–200 to 202 for the current profiler placement relative to the turbine.