Implicit PV cell parameters estimation used in approximated closed-form model for inverter power control

Abstract

This paper evaluates the use of a Photo Voltaic (PV) parameter estimation method based on implicit optimization algorithms and its use in power controller strategies by explicit model representation obtained with First and Second Order Approximation Models (FOAM, SOAM). An explicit function linking voltage, current and power of PV) cells is presented using the parameters obtained during the implicit estimation. The proposed method gives direct analytical solutions, resulting from a truncated Taylor series for the single diode PV-model. The analytical equations are easier to put into practical use and give solutions with an equivalent precision similar to the numerical method (Newton-Raphson Method) for the PV's cell voltage produced under particular conditions of temperature and solar radiance. The main benefit of this set of equations, useful also for optimal voltage estimation, is that offer an accurate and simple determination of the voltage profile using the manufacturer's data-sheet and PV plant's location for an specific design. The verification of the proposed method uses information from the manufacturer's datasheets of 12 different PV cells. The comparison of the results, for the analytical expressions versus the Newton-Raphson solution, validates the proposed method.