Control de seguimiento solar de alta precisión con autocalibración

Abstract

In the small Andalusian village of Arbuniel, in Sierra Mágina, Calle Sol goes from Plaza de España, where the church and the town hall, down to Calle Divertida (Funny Street), where Gustavo is making his breakfast "churros" since cockcrow (which does really happen here).next goal is the precise measurement of the tracking accuracy being achieved by the proposed hybrid calibrated tracking control. This will first require the development of a Tracking Accuracy Sensor (TAS) able to provide real time measurements of the sun tracking error. This sensor essentially consists of a collimating pipe mounted on top of an imaging electronic sensor, with the necessary signal conditioning electronics, developed along with the conversion equations necessary to compute a tracking error angle from its internal electric variables, and also with the calibration procedure to accurately obtain the internal construction parameters of the sensor that intervene in these conversion equations. This sensor will end up featuring the rather impressive resolution of 1/10.000 th degree within its 1° acceptance angle. Finally a monitoring system is built around the TAS mounted in the referred laboratory tracker, and by calibrating the controller against this TAS, a best case estimate of the tracking accuracy statistics, can be obtained for several variations of the calibrated routine here developed. In these experiments average daily accuracies of 0.05° are proven possible with accuracies better than 0.1°, 97% of the time.All tests in Chapter 3 to prove the correct operation of the calibrated sun tracking control, had to previously collect a set of in between fifty and a hundred sun position measurements, throughout a day from dawn to dusk, in order to feed the fitting of the calibration model. This was to be manually done, by aiming the laboratory tracker with its CPV modules to the sun till, according to some criterion, best pointing accuracy was obtained, and then recording axes position along with a measurement time stamp. This was a boring and error prone task, that had to be fully automated in order to be feasibly integrated in a commercial tracking controller unit, so it would run with the least amount manual operation and maintenance. In Chapter 4 the necessary hardware and algorithms to implement the automatic collection of sun position measurements are explained. But prior to the full description of the automatic measurement acquisition process, a review of the existent sun ephemerides and their accuracy is presented, including the set finally chosen for the tracking controller described in this work. Regarding sun position measurements these can first start by a preliminary search of the sun within the concentrator's tracking range, till this gets within the acceptance angle, a problem which as will be described can be attacked mathematically by resorting to the toolbox of Search Theory, a branch of Operations Research developed during WWII for antisubmarine warfare. In particular when helping the search with a coarse sun sensor such...