Any asynchronous motor which is ran at a higher speed than the nominal speed + slip will generate power when the motor coils are energized.
So a 1800 RPM motor ran at 1854 RPM because of the weight of the load will generate power.
( say a 1800 RPM motor with 3% slip will run up to 1854 RPM, then the motor will act as brake and generates power.)
This method is also used in ac crane motors, to reduce wear and tear on brakes while a load is hoisted down.
AC electric locomotives can also "generate" power this way in a descend with heavy freight trains while an uphill going train absorbs the extra power available.
