The Analysis and Optimization in Virtual Environment of the Mechatronic Tracking Systems Used for Improving the Photovoltaic Conversion [chapter]

Ctlin Alexandru, Claudiu Poz
2010 Motion Control  
The chapter presents researches in the field of increasing the efficiency of the solar energy conversion in electric energy, using tracking systems that change the position of the photovoltaic (PV) panel in order to maximize the solar radiation degree of use. From efficiency and safety point of view, we have selected a dual-axis equatorial tracking system, with two degrees of freedom. The both motions (daily and seasonal) are driven by rotary actuators, which integrate irreversible transmission
more » ... rsible transmission for blocking the system in the intermediary positions, between actuatings. The tracking system is approached in mechatronic concept, by integrating the electronic control system in the mechanical structure of the solar tracker. In this way, two main aspects are taken into consideration: optimizing the interaction between the mechatronic system components (the mechanic structure, and the control system); reducing the cost and time for the design process by replacing the traditional tests on hardware models, which are very expensive, with the testing in virtual environment. The study is performed by developing the virtual prototype of the mechatronic tracking system, which is a complex dynamical model. In fact, the virtual prototype is a control loop composed by the multi-body mechanical model connected with the dynamic model of the actuators and with the controller dynamical model. Using the virtual prototype, we are able to optimize the tracking mechanism, choose the appropriate actuators, and design the optimal controller. The functionality of the tracking systems is evaluated from kinematic and dynamic point of view (i.e. motions, forces), as well as from energetic balance point of view. The key word of the design is the energetically efficiency. Using the tracking system, the PV panel follows the Sun and increase the collected energy, but the driving actuators consume a part of this energy. In order to analyze our solution, we will compare the PV system with tracking with a fixed panel, in standard testing conditions. One of the most important advantages of this kind of simulation is the possibility to perform measurements in any point and/or area of the system and for any parameter. This helps us to make quick decisions on any design changes without going through expensive prototype building and testing. Source: Motion Control, Book edited by: Federico Casolo, ISBN 978-953-7619-55-8, pp. 580, January 2010, INTECH, Croatia, downloaded from SCIYO.COM Motion Control 554 Actual knowledge stage & original contributions The theme of the chapter belongs to a very important field: renewable sources for energy production -increasing the efficiency of the photovoltaic conversion. The researches in this field represent a priority at international level because provides viable alternatives to a series of major problems that humanity is facing: the limited and pollutant character of the fossil fuels, global warming or the greenhouse effect. The solution to these problems is the renewable energy, including the energy efficiency, the energy saving, and systems based on clean renewable energy sources, like sun, wind and water. The concept of sustainable development have been enounced for the first time in 1987, in the Brundland Commission Report, and subsequent adopted at the political level, so in the Conference for Development and Environment from Rio de Janeiro (1992) the participant countries have undertaken to develop national strategies for sustainable development -The Program Agenda 21. 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. Likewise, there are additional fields that use the solar energy, for example the hydrogen technology. The technical solution for converting the solar energy in electricity is well-known: the photovoltaic (PV) conversion. The PV systems can deliver energy on large-scale to a competitive price is the conclusion of the European Commission for Energy, in the report "A Vision for Photovoltaic Technology for 2030 and Beyond" (2004). The report emphasizes as the development of advanced technologies in the photovoltaic area, and a European strong and competitive industry will support the strategic initiatives concerning to the security and the diversity of the electric energy sources. The efficiency of the 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 rate of useful energy leaving the absorber is given by the difference between the rate of incident radiation on absorber and the rate of energy loss from the absorber (Goswami et al., 2000; Tiwari, 2002) . The degree of use of the solar radiation can be maximized by use of mechanical systems for the orientation of the PV panels in accordance with the paths of the Sun. Basically the tracking systems are mechanical 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 panel relatively to the Sun position on the sky dome, on the entire period of the day (the daily motion, from East to West), and also depending on the season (the seasonal/elevation motion). The orientation of the photovoltaic panels may increase the efficiency of the conversion system from 20% up to 50% (Abdallah & Nijmeh, 2004; Canova et al., 2007; Hoffmann et al., 2008) . In literature, the increasing of the photovoltaic efficiency is approached mainly through the optimization of the conversion to the absorber level, and this because the subject is mainly specific for the chemical and electrical engineering. In our vision, this is an interdisciplinary field that concentrates the competences of three fundamental domains: chemical, electrical, and mechanical. The solar energy conversion field interferes with the mechanical engineering there where the optimization process of the conversion uses tracking systems based on mechatronic devices (the maximum degree of collecting is obtained when the solar radiation is normal on the active surface). Having in view the operating principle, there are two fundamentals types of tracking systems: passive and active trackers. The passive trackers are based on thermal expansion of
doi:10.5772/6985 fatcat:qq34zjsbbvfn3heqgekxiw2gpi