Steady-State Analysis of the Constant Power Region in Distributed Maximum Power Point Tracking Architecture with Photovoltaic Applications

This study analyzes the steady-state characteristics of distributed maximum power point tracking (DMPPT) architecture in photovoltaic systems, focusing on full power processing (FPP) with series-connected direct current power optimizers (DCPOs). The decentralization approach of the FPP structure utilizes the independent DCPO for each PV module to solve mismatch issues. However, each PV-to-DCPO unit is not truly independent, and it is necessary to connect the output terminals of DCPO in series or parallel to meet the grid-connected voltage of the string-level inverter. The research examines the constant power region (CPR) of DCPO outputs and string-level performance under various mismatch conditions for boost and buck converter topologies. Considering practical constraints like duty cycle limitations, the study reveals that the existence and optimal string-level CPR width depend on environmental conditions and converter type. Severe mismatches can eliminate the optimal CPR in boost-based systems, while buck-based DCPOs generally maintain a positive CPR width, though extreme shading can significantly impact performance. These findings provide crucial insights into FPP-based DMPPT architecture limitations and emphasize the importance of considering real-world constraints in system design and evaluation.