Cooling method and cooling system for wind turbine generators

The invention discloses a cooling method for wind turbine generators. The cooling method includes the steps of setting the start triggering temperature T1 and the stop triggering temperature T2 of forced heat exchange; adopting the natural heat exchange mode for cooling when the temperature of a heating component is lower than the start triggering temperature T1; adopting the natural heat exchange mode and the forced heat exchange mode for cooling when the temperature of the heating component is higher than the start triggering temperature T1; and adopting the natural heat exchange mode for cooling when the temperature of the heating component is lowered to be lower than the stop triggering temperature T2. The invention further discloses a cooling system applying the cooling method. The cooling method is flexible, effective and reliable, and the power consumption of units can be lowered on the basis of guaranteeing normal work of the units. The cooling system can meet the higher heat dissipation requirements of the wind turbine generators on the premise of not enlarging the structural size or increasing the weight of a heat exchanger.