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

Abstract

This paper proposes a differential power processing (DPP) architecture applied to a series PV string which enables each PV element to operate at its local maximum power point (MPP) while processing only a small portion of its total generated power through the module integrated converters (MICs). The current processed through each converter is the difference between the local PV element MPP current and the local PV string current. This feature allows for a reduced current stress on the MIC components relative to the most common DPP topology. Thus, a higher system efficiency is realized at a reduced cost. A state space model of the proposed system is derived, and a comparison analysis is carried out with respect to the conventional DPP architectures. Additionally, a modular and compact design is proposed for a large number of PV panels in a series PV string. A hardware prototype is designed and built for 3 PV panels connected in series to validate the proposed architectures effectiveness and experimentally demonstrate its robustness. The modularity of the system is also tested to ensure low current and voltage stress on the MICs.