Efficient Approaches for Modeling and Simulating Photovoltaic Power Systems

Modeling and simulation of photovoltaic (PV) power systems have become increasingly important with wide acceptance and integration of solar energy in modern electric grids. The transcendental nonlinear equations describing the PV generator, which are coupled with the detailed switching models of the power electronic converters, generally result in slow and inefficient simulations, especially when long-term analyses are required. This paper focuses on simple and efficient modeling approaches that are suitable for long-term and large PV system analyses. This study provides a simplified PV-cell model and its parameterization, guaranteeing that the I-V characteristic curves pass through the typical points given in manufacturers' datasheets. Furthermore, several power interface models are provided for fast simulation purpose. A classical two-stage power processing system with intermediate dc link used as a string inverter, as well as a single-stage conversion unit used in distributed module-dedicated PV applications, are taken as application examples. The generalized modeling approach is thoroughly evaluated by comparing the simulation results with the experimental data of a practical 2.4-kW grid-tied PV solar unit. The proposed methodology is shown to have advantages over conventional modeling approaches to simulate long-term grid-tied operation.