Marine current generation system with embedded maximum point tracking, electrical losses minimization techniques and discontinuous PWM

This paper presents an Induction Machine (IM) based marine current (MC) generation unit with embedded maximum power point tracking (MPPT), Electrical Losses Minimization Technique (ELMT) plus Discontinuous PWM (D-PWM). The target is the development of a highly efficient MC generation system with high dynamic performance, able not only to track the maximum power available from the turbine rapidly, according to any sea speed variation, but also to minimize, at the same time, the IM´s the and converter´s losses. The proposed marine current generator is based on a back-to-back power converter topology with two voltage source inverters (VSI) and improves a previously developed neural based MPPT, integrating in the system also an ELMT feature. To reduce the VSIs switching losses, a D-PWM technique has been adopted, in place of the classic space-vector PWM (SV-PWM). The proposed marine current generation unit has been tested experimentally on a suitably developed test set-up. Results clearly show that the integration of the GNG MPPT and ELMT+D-PWM into the marine current generator control permits the active power injected to the power grid to be increased from 32 % at high sea speeds up to 650 % at low sea speeds and, in general, to increase the average active power in a low sea speed profile of almost 35 %.