Solar PV interface to Grid-Tie Inverter with Current Referenced Boost Converter

Abstract

A Solar Photovoltaic (PV) array may be interfaced with the Grid-Tie Inverter (GTI) either by direct connection or through a Boost Converter. In case of direct connection of PV with GTI the string voltage has to be maintained at the specified DC link Voltage level according to the Maximum Power Point (MPP) and the input range of the GTI by connecting the required number of PV panels to the string. In this case the Maximum Power Point tracking is done by giving the current reference to the inverter control and the response of the tracking may be limited by the inner current loops. Instead we can use a Boost converter to perform the dual function of stepping up the voltage and tracking the maximum power point. A Current Referenced Boost Converter has been proposed in this work in which the control is PWM mode with current feedback. The plant model is derived and a PI controller is tuned to satisfy the performance and stability requirements. The current referenced controller works well for Partially Shaded conditions and also has the ability to control the PV power by operating the PV array at any current reference in case of excess energy generation.