The maximum power point tracking concept is essential in PV systems to increase the power transfer capability and efficiency. The conventional methods to track maximum power point perform satisfactorily only under uniform solar irradiation, however under partially shaded conditions, PV array offers several local maxima along with one global maximum power transfer point on the P-V curve. This makes optimal tracking more difficult. This paper proposed an improved adaptive MPPT algorithm with varying step size to track the Global Maximum Power Point (GMPP) under different partial shaded conditions. First, the simulation model has been analyzed which is suitable for partially shaded conditions and then the proposed Variable Step-size Adaptive Maximum Power Point Tracking (VSAMPPT) method has been developed to track the global optimal power point for various irradiations. Here changing the duty cycle is not with fixed step size but with variable step size (Dstep), which depends on the square of the difference between the ratio of voltages to current and makes the proposed algorithm faster. The proposed algorithm keeps on adjusting its tracking strategy to find Global Peak Area (GPA) where the global maximum power point can be tracked down very easily. The proposed algorithm has been validated in the laboratory with dSPACE (DS1103) and tested with different case studies. The results demonstrate the effectiveness of the proposed concept over the existing MPPT methods like P&O method, Incremental Conductance (IC), and Adaptive MPPT methods in terms of speed of tracking global maximum power point, accuracy, and flexibility.

最大功率点跟踪概念在光伏系统中至关重要，可以提高功率传输能力和效率。跟踪最大功率点的传统方法仅在均匀的太阳辐射下才能令人满意地执行，但是在部分阴影条件下，光伏阵列在 PV 曲线上提供多个局部最大值和一个全局最大功率转移点。这使得最佳跟踪更加困难。本文提出了一种改进的变步长自适应MPPT算法来跟踪不同局部阴影条件下的全局最大功率点（GMPP）。第一的，分析了适用于部分阴影条件的仿真模型，然后开发了所提出的可变步长自适应最大功率点跟踪（VSAMPPT）方法来跟踪各种辐照的全局最佳功率点。这里改变占空比不是固定步长，而是可变步长 (Dstep)，这取决于电压与电流之比差的平方，并使所提出​​的算法更快。所提出的算法不断调整其跟踪策略以找到可以非常容易地跟踪全局最大功率点的全局峰值区域（GPA）。所提出的算法已在实验室中使用 dSPACE (DS1103) 进行了验证，并通过不同的案例研究进行了测试。