基于虚拟负载的快速变步长光伏电池最大功率点跟踪方法

Rapid Variable-step MPPT of Photovoltaic Cell Based on Virtual Load

光伏系统最大功率点跟踪的传统方法涉及步长和周期的选取,而变步长算法需依赖系统参数等条件,影响系统的跟踪响应速度以及稳定性。为了进一步加快最大功率点的搜索速度同时降低稳态时功率输出振荡,提出一种新型快速变步长搜索算法。通过定义虚拟负载线并结合I-V曲线实现最大功率点的定向跟踪,可以在数个运算周期将工作点锁定在最大功率点附近。再通过对容许误差的定义,实现了稳态时输出功率无振荡。实验证明了所提算法能够显著提高搜索速度并保证了输出的稳定性,能够适应不同外部环境的快速变化。

Traditional MPPT for photovoltaic systems involves selection of step and cycle,and the variable step algorithm depends on system parameters and other conditions,thus affecting system tracking response speed and stability. To further accelerate the search of the maximum power point and reduce steady-state power output oscillation,this paper presented a novel fast variable-step search algorithm,which,by defining a virtual load line and with help of directional tracking of the maximum power point realized through the I-V curve,can lock the working point to the proximity of the maximum power point in several operating cycles. Then,in the steady state,by defining the allowable error,we can achieve an output power without oscillation in the steady state. Experimental results show that the proposed algorithm can raise the search speed significantly,ensure output stability,and adapt itself to rapid changes in external environment.