部分遮挡条件下光伏阵列全局最大功率点追踪控制

Maximum Power Point Tracking Control for Photovoltaic Array Under Partially Shaded Conditions

光伏阵列的部分遮挡,使阵列功率电压特性呈现多峰,现有最大功率追踪方法在速度、准确度和可操作性方面仍有较大改进空间。首先,利用恒流源特性提出全局最大功率追踪新方法,即调整电流线法,该方法在P-U特性上沿着电流线斜率单调变化的方向不断调整电流线;然后对所提方法利用恒流源特性加快电流搜索过程并提高搜索终止条件的准确性;再从搜索过程和搜索终止条件两方面对现有0.8倍开路电压法进行改进;最后,以某光伏阵列3种遮挡模式以及遮挡模式间的变化为例,通过仿真验证所提两种方法(调整电流线法和改进的0.8倍开路电压法)均能准确、快速地追踪到全局最大功率点。所提方法为多峰最大功率追踪提供了新的思路。

Partial shading in photovohaic （PV） array makes the PV characteristic exhibit multiple peaks in power-volt- age curve and the existing maximum power point tracking （MPFF） methods have potentiality for improvement in preci- sion and operation. This paper carefully observed the constant-current-source feature in PV and proposed a new MPPT method--regulating current line method. This method regulated the current line based on the P-U characteristic in the monotonic direction of the current line＇s slope. Based on the constant-current-source feature, the proposed method sped up the tracking process and improved the accuracy of the searching-stop criterion. Furthermore, this paper im- proved the overall performance of the existing 80% of open-circuit voltage algorithm from the searching direction and searching-stop criterion aspects. Finally, taking three different partial shadings of some PV arrays and their shifting as example, simulation results verified that the proposed two methods above have a better performance in precisely and quickly tracking the global maximum peak point. The proposed methods offered a new vision for the MPPT in the multi- ple peaks condition.