What happens when there is too much wind? A tornado would not be too good for windmills.
Simple answer, though the engineering to make it happen is a bit tricky: Below 2-3 mph, there isn’t enough wind to rotate the blades. Between 3 and 8 mph, the blades turn, but cannot produce power.
Between 8 and 14 mph, they can begin to produce power, but if (when) the turbine is engaged, the blades stall out, can't keep up speed consistently, and the output current can't be sent to the grid. (Imagine your car trying to go up a hill with nothing on the accelerator - at idle, there isn't enough power to go “up” a hill, but you can coast down the same hill easily.)
Between 14 and 35 mph, you can produce power, the generator can be connected to the grid, and (some of the time) you can produce some of the rated power of the unit. Full rated power is ONLY possible at the top end of the wind curve: below 30 mph, you can't get 100 % power out of the generator.
Above 35 mph, you MUST secure the turbine and the generator: The blades explode and throw parts of the blades and generator and tower 1-2 miles as they shred the tower, power lines, and nearby people and buildings if they are not shutdown.