Grid connection for wave power farms

Linear generators used as direct-drive solution in wave energy conversion have the main advantage of higher efficiency and more simple and robust system. However there are some important drawbacks that should be solved to increase the reliability and feasibility. This paper will study in detail the problem of the power oscillation introduced intro the electric grid due to the zero speed point at the end of the stroke. Four different solutions are analyzed: first option is to plan the distribution of the point absorbers in the wave farm considering the most predominant wave period; second is to control the device by means of supplying some reactive PTO force in order to get a more reduced power oscillation, maintaining a compromise with the resonance situation which is desired to get the maximum energy transference; third consists on controlling the system with a hybrid strategy that includes a DC-link voltage control and direct power control; and finally the fourth solution consists on the addition of energy storage systems, independent of the generator to absorb and develop the excess and defaults of energy. Some of the solutions can be implemented together and the benefits of the resulting system increase.