在具有有源滤波功能的光伏并网(photovoltaic power generation and active filter, PV-AF)系统中,光伏电池的最大功率点跟踪(Maximum Power Point Tracking,MPPT)方法是其关键技术之一,针对常用的MPPT方法存在的问题,本文提出了一种改进的MPPT方法。该方法利用扰动观察法在最大功率点附近扰动的正向步数和反向步数基本相同的特点,判断系统工作点是否处于最大功率点(Maximum Power Point,MPP)附近。在此基础上利用变步长的扰动观察法,在远离最大功率点时采用大步长扰动,在最大功率点附近采用小步长扰动。在确定系统工作在最大功率点附近后,采用恒定电压法跟踪。扰动观察法的最大跟踪误差为1.5个电压扰动步长,提出的改进MPPT方法将最大跟踪误差降低为0.5个电压扰动步长。仿真和实验结果表明,该方法兼顾了跟踪的快速性、准确性和稳定性。
英文摘要:
In the photovoltaic power generation and active filter (PV-AF) system, Maximum Power Point Tracking (MPPT) of photovoltaic cells method is one of its key technology, In view of problems existed in common control methods of constant voltage method in MPPT, the paper proposed an improved method of MPPT. Using the characteristic that the number of positive steps and reverse steps is basically the same, judge whether the system is nearby the maximum power point or not. Based on this, a kind of variable step perturbation and observation method was put forward, when far from the Maximum Power Point (MPP), using large step to perturb, and when nearby the maximum power point, using small step to perturb. After confirming the system works near the maximum power point, use constant voltage method. The maximum tracking error of perturbation and observation method is 1.5 voltage perturbation step, the new MPPT method put forward reduce the error to 0.5 voltage perturbation step .The results of simulation and experiment showed this method gives consideration to rapidity, accuracy and stability.