A control strategy to reduce the effect of intermittent solar radiation and wind velocity in the hybrid photovoltaic/wind SCIG system without losing MPPT

The intermittent but complimentary nature of solar photovoltaic and wind mill generated power explored a new area of research for the hybrid PV/wind systems. This paper proposes a novel strategy for the control of power conditioning units to minimize the disturbances on the output power from the hybrid system, integrated with PV and wind turbine, in spite of highly intermittent nature of these sources. The proposed scheme balances the wide variation of power yield from wind and/or PV system and provides sufficient margin to the other sources (e.g. hydro, steam turbine, etc.) connected to the system to take over, so that to maintain power balance throughout the operation. The presented strategy makes use of high energy density ultracapacitor to absorb the effect of intermittent solar radiation and widely varying wind velocity. The MPPT associated with these sources remains unaffected and does not hamper overall generation from the system. The DC link of the conventional back to back topology of the wind farm is integrated with the PV panels with their MPPT trackers. The control strategy uses an inner fast current control loop and an outer slow voltage correcting loop for both the grid side VSI and the ultracapacitor converter. Simulation results are presented in the support of effectiveness of the proposed technique. A prototype is developed with the available 1.5kW PV installation, 1.2kW emulated wind turbine and ultracapacitor bank to validate some aspect of the proposed strategy.