基于功率二次微分的光伏系统改进MPPT算法研究

摘要

提出了一种基于功率二次微分的改进最大功率点跟踪(MPPT)算法(简称PQD-MPPT算法).算法在系统启动时采用恒定占空比启动,并给出了恒定占空比的求解公式,提出了根据功率变化量来调整跟踪步长的方法,当功率变化较大时,采用自适应大步长以使系统快速跟踪到最大功率点附近,反之较小时,根据功率对占空比的二次微分值的正负进一步划分跟踪区域:即当功率二次微分值为正时,采用固定大步长以使系统快速跟踪到最大功率点附近;当功率二次微分值为负时,采用自适应小步长以使系统能够稳定工作在最大功率点处.实验结果表明,与现有变步长MPPT算法相比,该算法具有良好的跟踪性能.%An improved maximum power point tracking (MPPT) algorithm based on power quadratic differential (in brief,PQD-MPPT algorithm) is proposed in this paper. The constant duty cycle method is adopted in its initial stage in the improved algorithm and the solving formula of the constant duty cycle is put forward. The adjustment method of the step according to the variation of power is also presented. When the power changes greatly,an adaptive large step is adopted to make the system to track near the maximum power point quickly. Otherwise, the tracking areas are divided into two parts according to whether the power quadratic differential is positive or negative. When the power quadratic differential is positive,a fixed large step is adopted to make the system to track near the maximum power point quickly. Otherwise,an adaptive small step is adopted to make the system to work stably at the maximum power point. The experimental results show that by comparison with the existing variable step MPPT algorithm,the improved algorithm has better tracking performance.