Advanced Drone-Based Alignment Measurements for Parabolic Trough Collectors

A novel drone-based measurement method for the automatic quality check of the field assembly of parabolic trough collectors has been developed. The module as well as receiver alignment of entire parabolic trough loops can be measured using commercially available drones equipped with a visual camera and RTK (real time kinematic) positioning. The measurement principle is based on the geometric relations between aperture edges of the parabolic trough collector and the absorber tube line, which both are measured seamlessly along the collector using robust edge detection algorithms. The measurement method replaces hook-rod based measurements of the receiver alignment and total-station based measurements of the module alignment in a fast and fully automated way while keeping high measurement resolution and accuracy. Due to its speed and versatility to measure receivers with and without protective foil and with the collector in arbitrary orientation, the measurement method can be applied in all project phases ranging from solar field construction over commissioning to operation. The paper presents the progress in the development of the method and the results of the validation measurements performed at the parabolic trough collector loop of the molten salt test platform (EMSP) in Évora, Portugal.