Method for commanding an upstream wind turbine in a wind farm

A method for commanding an upstream wind turbine in a wind farm having a plurality of spatially distributed wind turbines, the method comprising the steps of:

• determining a wind direction of a wind impinging the upstream wind turbine located upstream of a downstream wind turbine located downstream of the upstream wind turbine in the wind farm such that the wind causes wake to impinge on the downstream wind turbine,
• determining a wake steering control command for the determined wind direction, the wake steering control command being capable of improving the power production efficiency of the wind farm, being executable by the upstream wind turbine and being configured to at least partially deflect the wake from the downstream wind turbine,
• determining a first load level of the downstream wind turbine for a case where the determined wake steering control command would be executed by the upstream wind turbine,
• determining a threshold of a load level based on a second load level of the downstream wind turbine determined for a case where the determined wake steering control command is not forwarded to the upstream wind turbine and on a predetermined tolerance value, and
• forwarding the determined wake steering control command to the upstream wind turbine for execution therewith if the first load level is less than the predetermined threshold of a load level.