Robustness of a Renewable Energy Light Tracker Control System

A tracking photovoltaic (PV) system constantly adapts the angle of PV modules so that the irradiation angle and the light intensity remain constant and a maximum of electrical energy can be generated. This not only helps to exploit every minute of sunshine but also to make the best use of diffuse light all year round. Due to the changes of the conditions of operation, a tracking PV system shows signs of variation of its parameters. The aim of this research is to analyze the stability of a typical single axes PV system, affected by its parameter variations and improve its performance and robustness. This is achieved by the design of a specialized robust controller and the application of the method of the Advanced D-partitioning. This method for system stability analysis, suggested by the author in 2005, proves to be very efficient for graphical determination of the regions of stability in terms of system¿s uncertainty or variable parameters. The system robustness is examined after applying the robust controller and the obtained results demonstrate its insensitivity in terms of gain and time-constant variations.