Solar Photovoltaics Based Modified Power Quality Conditioner

This paper proposes an improved solar photovoltaics based unified power quality conditioner (UPQC). The proposed UPQC comprises of two single phase bridges- first bridge acts as a dynamic voltage restorer (DVR) as well as a boost circuit utilizing the shoot through periods and second bridge feeds the AC line in shunt. The boost capability facilitates transformerless grid connection of the second bridge unlike in the conventional designs where transformer is required due to limited DC link voltage along with the large DC link capacitance and higher input voltage from solar PV array. The proposed circuit thus provides a novel approach for integrating solar power into the grid along with power quality improvement at load side. A modified control strategy based on sinusoidal pulse width modulation (SPWM) is used to obtain sinusoidally varying shoot through intervals for this operation. The generalized mathematical formula of calculating shoot through duty cycle is also derived. The proposed circuit is extensively simulated in MATLAB and the results are presented.