太阳能光伏阵列在光照强度不均匀或者处于部分遮阴情形时，它的功率一电压输出特性曲线将出现多峰现象，这种情况下如果继续采用传统的最大功率跟踪法会造成光伏阵列输出功率的降低，从而导致光伏发电系统的效率的降低。

本文首先介绍了光伏并网发电的研究背景和意义，分析了国内外的现状和光伏并网发电关键问题的现状，接着对光伏电池的工作原理、等效模型和输出特性三方面进行了作了全面的分析 在此基础上，深入研究了热斑效应和部分遮阴条件下光伏电池不同的表现性能 然后，本文详细介绍了常用的最大功率跟踪方法的原理、优缺点和适用的场合及存在的一些问题，同时提出了一种适用于部分遮阴条件下的基于电导增量法的全局搜索算法。基于以上研究，本文又设计了实现最大功率跟踪控制的硬件电路，其中包括Boost电路和DSP的外围控制电路。

-　　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 PVsystem, 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