Design of a transformer-less grid connected hybrid photovoltaic and wind energy system

This paper presents a transformer-less grid-tie hybrid photovoltaic and wind energy system. The proposed hybrid system consists of a wind turbine, a Permanent Magnet Synchronous Machine (PMSM), a three phase diode bridge rectifier, an wind-side converter, Photovoltaic (PV) array, a dc-dc converter, a grid interface inverter and a T-LCL filter. The power extracted from hybrid wind-solar power system is transferred to the grid interface inverter by using a new dc-dc converter topology which is a fusion of CUK and SEPIC converters. This new topology lets the two sources to supply the load individually or simultaneously depending on the availability of the energy sources and keeps common dc voltage constant. As the suggested method is entirely transformer-less, it astonishingly reduces Total Harmonic Distortion (THD) less than 0.5%, minimizes the size of the system and provides efficiency up to 97%. The proposed design is mathematically modeled which is simulated via PSIM software and finally the results are presented to confirm the effectiveness of this hybrid system.