基于Simulink的光伏电池组件建模和MPPT仿真研究

Study of PV Module and MPPT Control Based on Simulink

根据光伏电池组建的物理特性等效电路及数学模型,基于Simulink仿真软件建立了光伏电池组件的仿真模型,模型的基本参数按照Solarex MSX60 60W产品参数设置,其他参数根据基本参数及数学模型计算得出。该模型可以实现在不同光照强度和温度下60W光伏组件的输出U-I特性,并且可以灵活地推广到其他功率等级的电池组件及其串并联特性的模拟。根据光伏电池的输出U-I特性,可以分析得到组件的U-P特性曲线为单峰曲线,故光伏电池存在最大功率工作点(MPP)。在此Simulink模型基础上研究了光伏组件最大功率追踪方法(MPPT)。在众多最大功率追踪方法中,电导增量法有着比较优秀的控制效果,因此本文着重讨论了电导增量法,对比分析了电导增量法及其两种改进方法(两种步长电导增量法和梯度变步长电导增量法)的最大功率追踪控制效果,这两种改进方法均对普通电导增量法中控制步长固定的不足做了修改。按照一天中光照强度变化的近似规律设置环境条件,仿真模拟光伏电池组件的MPPT控制,仿真结果进一步验证了模型准确性以及改进后的梯度变步长最大功率控制算法的优越性。

The simulation model of PV module in this paper is based on Simulink software,PV module＇s physical equivalent circuit and its mathematical model.Its basic parameters are the same as those of Solarex MSX60 60W,and other parameters are calculated with basic parameters and the mathematical model.This Simulink model can be used to show the U-I output characteristics of the 60W PV module under various insulations and temperatures.Meanwhile,this model can be applied to cases of other powers neatly and used to study module＇s parallel and serial characteristics.According to the output U-I characteristics,the U-P curve of the PV module is a single peak curve,which means that the PV module has a Maximum Power Point（MPP）.On the basis of this Simulink model,Maximum Power Point Tracking（MPPT） methods are discussed.Among various MPPT methods,the incremental conductance method（IncCond） has an excellent control effect,so it is mainly discussed in this paper,and its control effect is compared with two of its improvements,which are two step-sizes IncCond and gradient variable step size IncCond.The two improved methods have both relaxed the restriction of the fixed step in IncCond.Setting the environmental parameters of the simulation model with the approximate variation of insulation in a day,the MPPT control of PV module is simulated.The simulation results further verify the accuracy of the model and the improved MPPT algorithm.