Performance Enhancement of Single-Phase Grid-Connected PV System Under Partial Shading Using Cascaded Multilevel Converter

Conventional photovoltaic (PV) single/double stage grid - tie centralized and string inverters suffers from the problem of lower efficiency, high filter size, and limited depth of operation for remaining in connection with the grid, particularly under the lower insolation/partial shading condition. This paper proposes a staggered PV connection through cascaded multilevel converter (CMC) for PV-grid tie application utilizing independent maximum power point tracking controller, providing the larger depth of operation under partial shading condition with smaller filter size and electromagnetic interference (EMI). For dynamic and steady-state performance evaluation, a d-q frame-based control algorithm is investigated for the single-phase PV-CMC system. Furthermore, to establish the stability of the proposed controller, a detailed plant model is also investigated along with the detailed comparative analysis for operation of PV under partial shading condition for a conventional PV based centralized and string inverter vis-a-vis proposed PV-CMC approach. The improved performance analysis is demonstrated both through simulation and experimentation.