Patent ID: 8499708

Claim:
An active heave compensation system comprising: a control unit; an electric motor-generator configured to interact with a load and the control unit, wherein the control unit is arranged to control operation of the electric motor-generator, the control unit being arranged to: operate the electric motor-generator to drive the load in a first part of a wave motion cycle, and operate the electric motor-generator to regenerate in a second part of the wave motion cycle at least a part of the energy with which the load has been driven in the first part of the wave motion cycle; and an electrical storage element configured to buffer at least part of the regenerated energy for powering the electric motor-generator in a following cycle of the wave motion, wherein the electric motor-generator is configured to function as an electric motor to convert electrical energy into mechanical energy for driving the load in the first part of a wave motion cycle, and is configured to function as an electric generator to regenerate said at least a part of the electrical energy in the second part of the wave motion cycle when mechanically driven by a corresponding motion of the load.