Design, Architecture, and Real-Time Distributed Coordination DMPPT Algorithm for PV Systems

Abstract

The large-scale integration of photovoltaic (PV) systems for renewable power generation requires an intelligent and cost-effective solution in the emerging microgrid applications. In this paper, a fast real-time distributed coordination algorithm is proposed to address the challenge of extracting the maximum power from PV systems connected to microgrid under all uncertainties. A series PV string architecture with differential power processing (DPP) dc–dc converters is considered to extract the maximum power from PV systems by using distributed maximum power point tracking (DMPPT) method. A distributed digital controller architecture is developed for controlling the duty ratio of each DPP dc–dc converter in real time. The digital controller architecture consists of a main bus controller (BC) and submodule controller (SMC) for each DPP dc–dc converter. The BC coordinates the control operation of entire string through communication protocol with SMCs. The BC and SMCs are implemented with PIC18F8520 and PIC18F452 microcontrollers, respectively. An experimental prototype of a PV system is developed with six PV modules. The merits of the proposed algorithm are analyzed with respect to the communication protocol, control method, tracking efficiency, and tracking response time under varying operating conditions.