عنوان مقاله
بکارگیری سیستم الکترونیکی با اجرای الگوریتم بهینه شده در ردیاب های خورشیدی دو محوری
فهرست مطالب
مقدمه
محاسبه موقعیت خورشید
معماری ردیاب خورشیدی
فلوچارت فرآیند
مزایا و صحت سیستم
بخشی از مقاله
فلوچارت فرایند
بعد از فاز اولیه اکتساب مختصات GPS و اسکن سازه، نوبت به فاز زمان اکتساب و بررسی بیشتر یا کمتر بودن آن نسبت به زمان طلوع آفتاب می رسد. در صورت صحت این مسئله، فرایند با محاسبه پارامترهای روزانه نظیر زاویه میل خورشیدی، معادله زمان و … ادامه می یابد که برای محاسبه پارامترهایα وγ نسبت به موقعیت خورشید ضروری می باشند.
کلمات کلیدی:
Electronic system for improvement of solar plant efficiency by optimized algorithm implemented in biaxial solar trackers P. Visconti, V. Ventura Department of Innovation Engineering University of Salento Lecce, Italy paolo.visconti@unisalento.it vito.ventura@studenti.ingegneria.unile.it F. Tempesta, D. Romanello, G. Cavalera Cavalera Sistemi s.r.l. Galatone, Lecce, Italy f.tempesta@cavalerasistemi.it g.cavalera@cavalerasistemi.it Abstract — In this paper it is described an algorithm, implemented in a biaxial solar tracker, that can instantly calculate the sun position at the latitude and longitude of a set point. The algorithm can drive up to two engines which are able to change the position of a solar panel, in order to increase its efficiency, for tracking the sun in its movement from east to west (azimuth motion) and in its elevation up to solar noon (tilt motion). The whole system is adaptable to various types of structures as it involves a cycle of self-learning of the structure and consequently the adaptation of calculations to the tracker on which it is installed. Keywords – solar panel, solar tracker, azimuth motion, tilt motion I. INTRODUCTION A solar tracker is a mechanical device which is able to favorably move to the solar rays a photovoltaic panel, a solar thermal panel or a solar concentrator. The main purpose of a tracker is to maximize the efficiency of the device hosted on board. In a photovoltaic field the modules installed on a tracker are usually arranged geometrically on a single panel in order to avoid the use of a tracker for each module. According to their design features solar trackers are classified according to: their degrees of freedom, the type of power supply provided by orientation mechanism and the type of electronic control. Solar trackers are able to offer to the panel a single or dual axis freedom of movement. Among one degree of freedom trackers, can be mentioned: - Tilt (i.e. pitching) trackers which are the easiest to implement; they rotate around east-west axis (X axis). The panel is raised or lowered (usually manually twice a year) toward the horizon so that the angle to the ground is statistically optimal according to the seasonality. In practice, a tilt tracker is made using telescopic mechanical profiles in order to raise or to lower the solar panel respect to the horizon. Conceptually similar to the lifting shelf of a school desk these trackers offer a production increase of less than 10% that doesn’t justify a servomechanism. - Roll trackers are designed to “follow” the sun across the sky in its daily journey regardless the season of use. In this case the rotation axis is north – south axis (Y axis), while the height of the sun above the horizon is ignored. These trackers are suitable for low-latitude countries (including Italy, especially in the south) in which sun path is larger, on average, during the year. The required rotation to these structures is wider than the tilt, sometimes going up to ±60°. These trackers make each row of photovoltaic modules appears as a spit oriented toward the equator. - Tracker azimuth (i.e. yaw) have a degree of freedom with zenith – nadir axis (Z axis). To achieve this, the panel is mounted on a turntable servo, flush to the ground. The resulting increase in electricity production is approximately 25% The most sophisticated trackers have two degrees of freedom , by which they are able to perfectly align, in real time, the orthogonal of solar panels with solar rays. These trackers have guaranteed an increase of electricity production up to 35%-40%, even if they are characterized by a more complex design. Tracking systems of biaxial trackers can be astronomical, i.e. driven by a software that calculates instantly the sun position and moves the panels accordingly (as the algorithm presented in this paper) or light-sensitive cell, capable of moving the panels towards the strongest light source (sun) in every single moment. On the basis of power required for the movement, the trackers can be divided into active, if set in motion by motors, or passive, when set in motion by independent physical phenomena as thermal expansion of gas, etcetera. The active trackers can be classified by the type of electronic control which drives the movement: in the analog type the control is generated based on information of a sensor that detects the position of the brightest point in the sky while in the digital case the control comes from a microprocessor which, through special stored tables, knows in every moment the position of the sun in the sky.
