Radar Technology For Heliostat Position Control

Abstract

The Solar Institute Jülich (SIJ) and the Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR) ascertains by the feasibility study HelioScan the capability of a new innovative method of determination the positions of heliostats of a heliostat field, using a radar system to manage their positions. Other remote control systems using photo optical or laser systems were tested for comparison. The almost deployed detection systems for position analysing are contact detection systems and have fixed encoders at each driver axis or motor of the heliostat. In the project HelioScan different fare detection systems are analysed on their utilizability. This paper opens a special focus on the investigations of the radar technology in the project. The new single remote monitoring sensor system should have low cost in terms of manufacturing, installation, operation, calibration and maintenance. The sensor system shall also be applicable regardless of the type of mirror, which increases the range of applications and marketing opportunities. To investigate the suitability of short-wave radar, photo optical and laser systems, first experiments have been conducted at the heliostat field of the experimental solar thermal power plant in Jülich (STJ). Using an adapted test radar of FHR, millimetre radar waves were directed from the research platform of the solar tower to the heliostat field. The reflected signals were evaluated by using high-quality sensors and new computational algorithms to analyse the quality of the position information. The results of the measurements show until now that the speed advantages of a surface radar scan allow a rapid and simultaneous detection of many heliostats, offering the capability of a fast analysis of the whole field. Further details of these first radar remote monitoring field tests and results of the signal analysis of the heliostat position are presented.