Research On Maximum Power Tracking Method Of Photovoltaic Power Generation System

Maximum power tracking control technology has great significance to improve theefficiency of the photovoltaic power generation system, at the same time, it is also a researchhotspot in the field of photovoltaic power generation. Based on photovoltaic power generationsystem, this paper aimed at the maximum power tracking problem for the study, the maincontents are:Firstly, based on the photovoltaic cells’ universal model, for simplifying it, ignoring theminor factors influence on the photovoltaic cells’ output characteristics, a simplifiedmathematical model was got. Through comparison and simulation with the universal model,the simplified model not only has a simple form, but can meet the precision of the engineeringuse, making a foundation for the subsequent study of maximum power tracking in this paper.Secondly, based on the problem of maximum power tracking of independentphotovoltaic power generation system, according to the rapidity of short circuit currentmethod in response to the environment mutation and the high precision characteristic ofNewton method, putting forward a new method for maximum power tracking by combiningshort circuit current method with Newton method, the new algorithm firstly adjusts the PVcells’ working points to the nearby of the maximum power point with short circuit currentmethod, then using Newton method to complete higher precision of the maximum powertracking. Through the simulation and analysis, its accuracy and rapidity was verified.Finally, based on the circuit topology of single-phase photovoltaic grid-connectedsystem, and dividing the system into two parts: dc and ac, through the analysis of theimpedance characteristics of the two parts’ circuits, demonstrating the PV grid powergeneration system has the uniformity in terms of dc-ac impedance. At the same time, based onthis uniformity in dc-ac impedance, using the impedance modulus method to achieve themaximum power tracking of PV power generation system. Through comparison andsimulation of the effect of tracking with INC method and P&O method, the higher stabilityand the better rapidity of the proposed method was verified.