改进功率预测变步长扰动法在光伏MPPT中的研究

RESEARCH ON IMPROVED VARIABLE STEP PERTURBATION ALGORITHM FOR POWER PREDICTION IN PHOTOVOLTAIC MPPT

针对最大功率点跟踪技术在光伏发电系统中的应用和研究现状,提出一种改进功率预测变步长扰动法。首先分析光照强度在一个采样周期内非线性变化时功率预测法会因功率预估值偏差较大而产生误判这一现象,为减少功率振荡损失,基于牛顿插值法建立三点采样函数模型以减少预测功率值与实际功率值的偏差。其次在确定变步长的过程中纳入光照强度变化这一动态因素,通过引入对光照强度变化的修正系数提出一种变步长的确定方法。最后搭建光伏系统模型及车载光伏实验平台进行最大功率点追踪仿真,结果表明改进功率预测变步长扰动法在改善误判和失效问题的同时能更加平稳地追踪最大功率点。

In view of the application and research status of tracking technology of maximum power point trackers(MPPT) in photovoltaic power generation system,an improved variable step perturbation method for power prediction is proposed. Firstly,this paper analyzes the phenomenon that the power prediction method can misjudge the estimated power due to the large power estimation deviation,when the sun light intensity change is nonlinear within a sampling period. In order to reduce the power oscillation loss and the deviation between the predicted power value and the actual power value,a three-point sampling function model is established based on Newton interpolation method. Secondly,in the process of determining the variable step size,the dynamic factor of sun light intensity change is considered. On this basis,a method of determining the variable step size is proposed by introducing the correction coefficient of sun light intensity change. Finally,a photovoltaic system model and onboard photovoltaic experimental platform is built for MPPT tracking simulation. The results show that the modified variable step perturbation method for power prediction can track MPPT more stably and but also improve the problems of misjudgment and failure.