基于二次插值的光伏MPPT改进算法研究

Research on photovoltaic MPPT improved algorithm based on lagrange quadratic interpolation method

为了提高光伏电池最大功率跟踪(Maximum Power Point Tracking,MPPT)的跟踪速度,减小稳态波动,提出一种将拉格朗日二次插值与电导增量法相结合的MPPT算法。首先,分析了光伏电池的输出特性以及定步长电导增量法的跟踪原理和优缺点;在此基础上,基于拉格朗日二次插值,对定步长电导增量法进行优化,并分析了步长对该方法的稳态误差和跟踪速度的影响;为消除这一影响,提出了二次插值与变步长电导增量法相结合的MPPT算法。仿真结果表明,拉格朗日二次插值和变步长电导增量法相结合的MPPT算法可以迅速稳定地响应外部环境的变化,有效地解决了MPPT跟踪速度与稳态波动之间的矛盾。

In order to improve the tracking speed and reduce the steady surge of photovoltaic MPPT,a MPPT algorithm is introduced in this paper,which is based on Lagrange quadratic interpolation and conductance incremengt method.The output characteristics of photovoltaic cell and the tracking principle of fixed-step conductance increment method are firstly analyzed.Based on this,the fixed-step conductance increment method is optimized by using Lagrange quadratic interpolation,and the influence of selected step on this method is revealed.To eliminate the influence,a MPPT algorithm combined Lagrange quadratic interpolation with variable-step conductance increment method is proposed.Simulation results show that the improved MPPT algorithm can respond to the external environment change rapidly and steadily and resolve the contradiction of tracking speed and steady surge effectively during the process of MPPT.