An Improved PV to Isolated Port Differential Power Processing Architecture for Solar PV Applications

Abstract

This paper presents a novel topology based on Differential Power Processing (DPP) for feeding solar power into a DC micro-grid. For a PV-to-Isolated Port bus DPP topology, the voltage of the isolated port may fluctuate beyond permissible limits. The voltage level of the isolated port falls below or goes above the reference voltage due to supply or absorption of large mismatched currents, respectively by the DPP converters, in case of significant partial shading for a long duration of time. The proposed topology solves this problem using a bi-directional two-switch flyback converter between the isolated port and the string voltage bus which facilitates exchange of power between them. The development of the proposed architecture from a PV to Isolated port bus DPP topology is discussed. The system has been designed and modelled for ten PV panels. Detailed simulation results have been presented to validate the proposed architecture which show that the two-switch flyback converter maintains the voltage of the isolated port within desirable levels when it is discharged or overcharged due to mismatch between the panels for a long duration of time.