AC Dynamic Parameters Extraction of Shaded Solar Cells Based on Analytical Methods and LMLS Algorithm

摘要

This paper aims at investigating the ac dynamic parameters of partially shaded solar PV cells. We employ analytical and numerical methods to extract the parameters of ac dynamic model of a PV cell. Particularly, the parameter identification process is based on the small signal impedance model of solar cells and its associated transfer function. This model can reflect the static and the dynamic performances of the solar cell at low and high frequencies. The analytical method utilizes mathematical equations derived from Nyquist and Bode plots, whereas the numerical method exploits Levenberg-Marquardt Least Squares (LMLS) algorithm. In this paper, we have also designed an adapted experimental laboratory circuit to measure the PV cells frequency response. The entire procedure, including the acquisition and calculation systems is completely automated using C# programming. Accordingly, we developed a low-cost setup that allows partial shading emulation as well as high power and frequency measurements. Our results demonstrate that the numerical method can achieve a better fit of data with an accuracy of 91%. Moreover, it can estimate the same parameter values in a short time with high precision.