基于模糊控制的无电压传感器光伏系统MPPT研究

Research on the fuzzy control based MPPT of voltage sensor-less photovoltaic system

基于光伏并网发电系统直流母线电压恒定的特点,定义了一个由光伏电池输出电流和Boost变换器占空比表示的等效功率,根据该等效功率与Boost变换器占空比的关系深入分析了一种无电压传感器最大功率点跟踪(MPPT)算法。为了实现变步长跟踪以保证MPPT算法的快速性,将模糊控制与无电压传感器MPPT算法相结合,改善了系统的动态特性。基于Matlab/Simulink平台搭建了光伏并网发电系统模型,将该算法与传统的扰动观测法进行比较,结果表明,在保证稳态精度的基础上,基于模糊控制的无电压传感器MPPT算法具有更快的跟踪速度,并在光照强度和温度变化的条件下证明了该算法具有更好的鲁棒性。

Based on the fact that the DC bus voltage of photovoltaic grid-connected system is constant, an equivalent power is defined by the current of the photovoltaic cell and the duty cycle of the Boost converter. A voltage sensor-less MPPT algorithm is analyzed according to this equivalent power. In order to realize a variable step-size algorithm to ensure the speed of MPPT,the proposed MPPT algorithm is combined with fuzzy control. As a result, the dynamic performance of the system is improved. Then a photovoltaic grid-connected system simulation model based on the Matlab/Simulink is established. The comparison of the proposed algorithm and perturb observe algorithm indicates that the former has higher MPPT speed besides good steady accuracy.Experiments under the condition of variable illumination and temperature prove that the proposed algorithm has better robustness.