Bi directional motor generator

[JVAero]

I have a cable that is under oscillatory load. I would like a motor generator to generate electricity when the cable is under tension, and run as a motor when the cable goes slack. I would also like to able to prescribe the range of tension, so that plays cable in/out to maintain a prescribe, time-varying tension. What type of motor / generator is required for this application, and what type of controller is required to maintain time varying tension on the cable. The motor / generator will have to run bi directional. The frequency of the oscillatory load varies between 2 to 15 seconds.

 

[Hoxton]

What is powering the cable?

Remember that any generated power comes from the cable, or have you invented perpetual motion?