MPPT Technology Under Partial Shading In PV Grid-Connected System

Solar energy is accepted commonly because of its safe and unusual advantages, it is imperative to accelerate the development of solar energy. And improving the technology of solar energy also makes great significance to enhance the energy structure and building a pollution-free energy system.It is widespread that there is uneven light intensity, partial shading and other phenomena in various photovoltaic (PV) power generation systems, this phenomenon will not only affect the power output of the PV arrays, but also will cause problems with the safety and stability. The P-U characteristics of PV array will appear multi-peaks in the partial shade condition, making the conventional maximum power point tracking(MPPT) algorithm fail to apply in this case.Firstly, the paper introduces the grid-connected PV system research background and significance, the current situation at home and abroad, key issues of grid-connected PV system, it also analyzes the electrical characteristics and equivalent model of PV cell, it also analyses the hot spot effect and the difference performance of PV cell in partial shading; then, the paper introduces the principle of the conventional maximum power point tracking methods, its advantages and disadvantages, applicable occasions and problems, while the paper puts forward to a global search algorithm based on incremental conductance (INC) method which can apply in partial shade conditions. Secondly, the paper introduces the overall structure of the PV power generation system including Boost circuit and DSP peripheral control circuit.Finally, the paper builds MPPT of the PV power generation system simulation platform by Matlab/Simulink; simulates three different partial shade conditions; analyses the advantages and disadvantages of two methods to verify the effectiveness of the algorithm.