Power decoupling in solar PV system using partial power processing converter

To interconnect solar photovoltaic (PV) with the single phase grid, DC/AC inverters are used as interface. For tracking maximum power from each solar PV string, DC/DC converters are connected between solar PV strings and inverters. This ensures each strings operates at its maximum power output irrespective of variation in solar radiation among different strings. Conventionally, DC-DC converter used for this application would process the complete power of the string. This full power processing (FPP), architecture leads to high conversion losses. This paper suggests a flyback based partial power processing converter, which offers high conversion efficiency, as compared to conventional dc-dc converters. In addition, the proposed scheme also eliminates low frequency (twice the power frequency) oscillations in string voltage in case of single phase inverters, thereby increasing the power extraction efficiency. Key advantages of the proposed scheme are power decoupling, low conversions losses, high extraction efficiency and distributed maximum power point tracking (DMPPT). Detailed simulation studies are performed to validate the performance of the proposed scheme. Comparison of the proposed scheme with the conventional full power processing scheme is also included.