Investigations on Power Transfer Operating Spaces of Solar Panel Companion Inverters

摘要

Solar Panel Companion Inverter (SPCI) has been proposed as an H - bridge inverter embedded with a Photo Voltaic (PV) module. Each inverter converts the DC voltage output of the PV module, to a quasi-square wave voltage with variable pulse width. When these voltages are aggregated across multiple panels connected in a series string, they synthesize an AC waveform that can be interfaced with the power grid. However, the grid connected SPCI systems have been controlled such that they transfer real power into the grid at unity power factor. As low voltage ride through requirements are becoming increasingly important for grid tied inverters, SPCIs are required to participate in reactive power exchange with the grid along with the baseline real power transfer. Within the voltage and current constraints of the power devices, modern day inverters are expected to perform in two quadrants (real power source P>o, reactive power source Q>0) and (real power source P>0, reactive power sink Q<;0) as compared to the inverters in the past which have been operating in only one axis (real power source P>0, no reactive power i.e. Q=0). The objective of this paper is to present a generalized analytical discussion for real and reactive power transfer scenarios for single phase grid tied SPCIs. Also, simulation and experimental results for the scenarios implemented using sorting algorithm is presented.