Optimal design of the controller for a photovoltaic tracking system using parametric techniques

ANNALS of the ORADEA UNIVERSITY. Fascicle of Management and Technological Engineering, Volume IX (XIX), 2010, NR1

OPTIMAL DESIGN OF THE CONTROLLER FOR A PHOTOVOLTAIC TRACKING SYSTEM USING PARAMETRIC TECHNIQUES
ALEXANDRU Cătălin ”Transilvania” University of Braşov, Product Design & Robotics Dept., calex@unitbv.ro
Keywords: photovoltaic system, tracking mechanism, controller synthesis, designof experiments. Abstract: The paper is approaching the field of increasing the efficiency of the photovoltaic modules by using solar tracking systems. The main task in optimizing the tracking systems is to maximize the energetic gain by increasing the solar input, and minimizing the energy consumption for tracking. The tracking system is approached in mechatronic concept, by developing the virtualprototype, which is a control loop composed by the multi-body mechanical model connected with the dynamic model of the actuators, and with the controller model. The paper is focused on the optimal design of the PID controller for a PV tracking system, by using the optimization capabilities of the virtual prototyping environment ADAMS of MSC Software, based on DOE (Design of Experiments)parametric technique.

1. INTRODUCTION The solar energy conversion is one of the most addressed topics in the fields of renewable energy systems. The present-day techniques allow converting the solar radiation in two basic forms of energy: thermal and electric energy. The technical solution for converting the solar energy in electricity is well-known: the photovoltaic (PV) conversion. The efficiency ofthe PV systems depends on the degree of use and conversion of the solar radiation. The energy balance refers to the surface that absorbs the incoming radiation and to the balance between energy inflow and energy outflow. The degree of use of the solar radiation can be maximized by use of mechanical systems for the orientation of the PV modules in accordance with the paths of the Sun. Basically thetracking systems are mechatronic systems that integrate mechanics, electronics, and information technology. These mechanisms are driven by rotary motors or linear actuators, which are controlled in order to ensure the optimal positioning of the PV module relatively to the Sun position on the sky dome. The orientation of the photovoltaic modules may increase the efficiency of the conversion systemfrom 20% up to 50% [2-4]. A photovoltaic module with tracking is efficient if the quantity of electric energy produced by system is substantially greater than the sum of the energy produced by the same module without tracking (fixed) and the energy consumption for tracking. Therefore, the main task in optimizing the tracking systems is to maximize the energetic gain by increasing the solar input,and minimizing the energy consumption for realizing the motion law. For achieving the energetic efficiency condition, all the components of the tracking system (the mechanical device, the actuators, the control system & the controller) are important, as well as their integration. No less important, there are the economical aspects, concerning the cost of the product (which includes the designcost), the reliability, and the pay-back period. In the last years, we have developed a lot of studies concerning the optimization of the PV tracking systems, considering with priority the mechanical structure and the motion law of the PV modules, for azimuthal, equatorial and pseudo-equatorial tracking systems. The basic objective of this paper is to improve the behavior of the solar trackers fromthe control system point of view, through the optimal design of the controller. The mechanism was previously optimized from geometric and motion point of view, the tracking strategy aiming to optimize the angular field of the motion and the actuating time for the step-bystep orientation [1].

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ANNALS of the ORADEA UNIVERSITY. Fascicle of Management and Technological Engineering, Volume IX...