Optimal Design of the Two-Loop Control System for a Single-Axis Solar Tracker

The paper deals with the optimal design of the control system for a sun tracking mechanism, which is used to increase the efficiency of the photovoltaic (PV) modules. The tracking mechanism is one of single-axis (mono-axial) type, which is able to realize the orientation of the PV module according to the daily movement axis (so the East to West movement, that is, from sunrise to sunset). The rotation axis of the PV module is tilted toward the local horizontal plane at an angle equal to local latitude (that is, it is arranged parallel to the polar axis), which allows the module to be oriented with good accuracy relative to the sun trajectory throughout the day light. The tracking mechanism is driven by using a linear actuator, which is controlled by means of an open-loop scheme (based on predefined tracking program). Controller optimization aims at determining the optimal values of its proportional, integral and derivative gains, in order to minimize the tracking errors, i.e. the differences between the imposed and current position angles of the PV module. The study is carried out by using the virtual prototyping package ADAMS of MSC.Software.