A fast and accurate generalized analytical approach for PV arrays modeling under partial shading conditions

Abstract

This paper proposes a generalized analytical approach to model the photovoltaic (PV) arrays under partial shading conditions (PSC). The proposed method is simple: it requires only the standard test condition (STC) parameters of the PV modules and the irradiance level imposed on each module. By using this information, the P-V and I-V curves of shaded PV arrays are obtained by simple steps. Firstly, the current-voltage (I-V) curves for all assembled submodules receiving the same level of irradiance are generated using the two-diode model. The parameters of the latter are computed using a fast parameter extraction method. Secondly, the I-V curve of each shaded string is computed using the computed I-V curves of its submodules. In the last step, the resulted I-V curve of the array is obtained by summation of all I-V strings curves. The proposed method is simple, fast, and can be coded in any development platform. Besides, the prediction accuracy is enhanced by incorporating the real effect of bypass and blocking diodes in the model. Furthermore, the proposed method could be generalized for any number of series/parallel connections in a shaded PV array. The method can be useful to generate critical shading patterns for maximum power point tracking (MPPT) algorithms evaluation. It can also be used as a tool to obtain instant shading patterns in PV array simulators.