A Novel Differential Power Processing Architecture for a Partially Shaded PV String Using Distributed Control

Abstract

This article proposes a differential power processing (DPP) configuration applied to a series photovoltaic (PV) string. The proposed configuration operates each PV element at its local maximum power point (MPP) while processing only a small portion of its total generated power through the modular-integrated converters. The current processed through each converter is the difference between the local PV element MPP current and the local PV string current. This leads to higher energy capture at an increased conversion efficiency while overcoming the difficulties associated with unmatched MPPs that result from partial shading, temperature gradients, manufacturing defects, and nonuniform cells aging. A state-space model of the proposed system is driven, and a comparative analysis is carried out with respect to the conventional DPP architectures. Additionally, modular and compact design is proposed for a large number of PV panels in a series PV string. The authors designed and built a hardware prototype for three PV panels connected in series to validate the proposed configuration effectiveness and experimentally demonstrate its robustness.