Power controller design for maximum power tracking in solar installations

Abstract

A state space approach to the design of a maximum power point (MPP) tracking system for photovoltaic energy conversion is presented. The problem of optimal-power control of a nonlinear time-varying system is reduced to an ordinary problem of dynamic system stability in state space by applying MPP conditions in controller design. The resulting tracking system searches for the reference point and tunes the converter for maximum power delivery to a load that may represent an end-user, or an energy-storage element, or a power grid-interface. The proposed design procedure for the MPP tracking system ensures a global asymptotic stability under certain conditions, and a minimum degree of the dynamic feedback. The design is verified using the Virtual Test Bed, demonstrating accurate MPP tracking capability under unpredictable weather change, parameter variation, and load disturbance. The tracking system can be applied either to stand-alone or grid-connected photovoltaic installations, and can be implemented in either analog circuitry or a digital microcontroller. © 2004 IEEE.