A wind turbine is provided. The wind turbine includes a mechanical system, an electrical system and a controller. The controller is for determining an electrical capability limit of the electrical system according at least in part to one or more operating conditions of the wind turbine and one or more environment conditions of a site of the wind turbine, comparing the electrical capability limit of the electrical system and a mechanical capability limit of the mechanical system, and controlling the electrical system to operate at the smaller one of the electrical capability limit and the mechanical capability limit. A method for controlling a wind turbine comprising a mechanical system and an electrical system is also provided.