The constant speed you mentioned is one of the early wind turbines, which uses blade stall protection to achieve constant speed. It is modeled when designing the blade profile. If the power needs to be adjusted slightly, the installation angle can only be adjusted later, but the blade itself will not rotate axially. The generator uses squirrel-cage motor.

When the wind speed is small, the torque is small and the corresponding dynamic rate is also small. After reaching the rated torque and speed at high wind speed, due to the design form and installation angle of the blades, when the wind speed reaches the rated wind speed, the blades will have stall effect. That is to say, when the wind speed increases, the rotation speed will not increase, but will decrease slightly. This is the aerodynamic principle of the blade itself. At high wind speed, a lot of turbulence is formed on the leeward side of the blade, which leads to the decrease of the overall lift of the blade, thus controlling the speed.