三相光伏系统中一种新的最大功率点追踪方法

A novel maximum power point tracking method in three-phase photovoltaic system

为了提高光伏器件利用效率,对最大功率点跟踪(MPPT)方法进行研究.针对扰动观察法在天气快速变化时,会产生误判这一问题,在功率差值-扰动观察法(dP-P&O)的基础上,引入光照变化加速度的概念,对光照变化过程进行更精确的建模,减少最大功率跟踪过程中的误判现象.同时,利用功率守恒原理,对光伏阵列输出和逆变器输出功率之间的关系进行分析,得出通过比较扰动前后并网电流的变化来实现MPPT控制的方法.该方法不需要对光伏阵列的输出电压和电流进行检测,降低了光伏系统的成本.仿真和实验结果表明,该方法是可行的,并且系统能够保持稳定性.

In order to improve the efficiency of photovltaic devices, the maximum power point tracking （MPPT） method is studied. Perturbation and observation method （P8~O） is one of the popular methods though, it is unable to determine the right tracking direction when the weather changes rapidly. In order to reduce the mistake of MPPT, the concept of acceleration of illumination changing is introduced to rebuild the process of illumination changing based on dP-P8~O method. Meanwhile, this paper analyzes the relationship between the power of PV cells and the power of the inverter by power equilibrium principle, and gets a conclusion that the MPPT method can be implemented by compartng the sequential sampled output current of the inverter. This method is not required to detect the output voltage and current of photovoltaic cells, so the cost of system is reduced. Simulation and experimental results show that the method is available and the system can maintain stability.