Irradiance and temperature transient sensitivity analysis for photovoltaic control

Abstract

This paper analyzes control scheme sensitivity to changes in irradiance and temperature around the maximum power point (MPP) for photovoltaic (PV) panels. Conventional control schemes such as constant voltage, current, and resistance, as well as a newly introduced voltage-offset resistance control (VRC) are compared. Based on experimental PV data and a validated model, VRC is found to have the lowest sensitivity to typical transients. Stability analysis of a buck and boost converter under VRC indicate that some ranges of the equivalent resistance are stable while others can cause instability. Two established PV control methods are assessed in terms of transient stability and three additional low-sensitivity methods utilizing VRC are outlined. These methods are applicable to PV controllers taking infrequent measurements that hold the control line steady between samples.