局部阴影条件下光伏阵列的建模与分析

Model and Analysis of Photovoltaic Array Under Partial Shading

阴影的存在使光伏阵列的输出伏安特性曲线呈阶梯状,相应的功率电压曲线含有多个局域峰值,现有的常规电池模型不再适用,因此需要建立适用于阴影条件下光伏阵列的数学模型。以太阳能电池的工程用模型为基础,结合电路的串并联理论,对局部阴影条件下光伏阵列进行了详细的分析,从理论上推导出部分遮挡情况下光伏阵列的数学模型可以用分段函数表述,并对其进行实验验证,证明所建模型能较好地描述阴影条件下光伏阵列的输出特性。利用所建模型对阴影条件下具体光伏阵列在不同阴影数量、遮挡模式、光照、温度下的工作情况进行仿真分析及计算,结果表明:局部阴影对阵列输出特性的影响因阵列的格局、阴影的数量和分布以及温度、光照、遮挡模型的不同而有所差异。

Partial shading makes output voltage-current curve of photovoltaic （PV） array stair-stepping and corresponding power-voltage curve possessing local peak values, so existing conventional PV array model is no more suitable and it is necessary to build a new mathematical model of PV array that is suitable for partial shading condition. Based on engineering model of PV array and combining with series-parallel connection of electric circuit, the PV array under partial shading is analyzed in detail and it is derived theoretically that the mathematical model of PV array under partial shading can be expressed by piecewise function, and experimental verification of this conclusion is performed to prove that the built PV array model can describe the output characteristics of PV array under partial shading well. Using the built model, the operating conditions of concrete PV array under different number of shades, sheltering modes, illumination and temperatures are simulated. Simulation results show that the influences of partial shading on output characteristics of PV array are different and are dependent on different patterns and distributions of PV arrays and different number and distribution of shades as well as temperatures, illumination and sheltering modes.