The energetic efficiency of the PV panels can be sensibly increased using tracking systems. In their control program design the main parameters are the motions amplitude and the tracking steps number which are subject of optimization based on maximization of the received direct solar radiation on panel, on minimization of the driving energy for tracking, on PV type and on local meteorological conditions. In the paper, these parameters are analyzed for the azimuthal tracking, based on maximization of the received direct solar radiation on panel for a specific day and cloudless sky. An appropriate numerical simulation model, based on MatLab software, was implemented. The results and the correlations between the parameters, obtained for the daily orientation are in designing the seasonal and yearly tracking control program design.
Abstract. The paper presents results on a novel low concentration system for photovoltaic/ hybrid module, its geometric modelling and the optimal working parameters. The low concentration system is build up of a PV module and two mirrors, one on the left side and symmetrically on the right side along the length of the PV module. Our objective is to maximize the received direct radiation of the PV or hybrid module, maintaining an overall geometric size of the system as small as possible with a minimum number of the tracking steps. Two cases were considered: the first case when the reflected solar radiation from each mirror sweeps the whole surface of the PV module increasing by almost 2x the amount of radiation that sweeps the PV-surface; the second case when the reflected light from each mirror partially sweeps the PV-module surface, building together one cover of light on the plane and increasing the amount of radiation that falls on the module surface around 1x. Although the total amount of radiation that falls on the photovoltaic/hybrid module surface in the second case is far less than in the first situation, the overall size of the system is strongly reduced.
Turbidity factor (T R) varies from one geographic area to another according to the specific in-field conditions: site altitude, atmospheric pollution, water vapor and gasses in the air etc. Therefore the turbidity factor is a synthetic parameter that offers information on how much solar radiation is lost when passing through cloudless atmosphere and moreover it can be used to evaluate the atmospheric pollution on a given site. To obtain a realistic and accurate T R estimation for Brasov, Romania, the beam solar radiation values, registered by the Delta-T meteorological station, were modeled according to three stages of refinement, based on a method proposed by the German meteorological services (the considered meteorological database contains registrations for 2006-2009 interval). For the first and second stages, were considered only the days with the highest and densest beam solar radiation values, registered on each month; accordingly, the daily mean solar radiation values and the correspondent T R were calculated. Because the first stage results were inconsistent to the real situation, on the second stage were considered only the beam radiation registrations corresponding to a solar elevation above 20°; still the results were inconsistent with reality. On the third stage, the single instantaneous maximum beam solar radiation value is considered, for each month, based on 2006-2009 database, and only for these twelve values is calculated the corresponding monthly T R ; the consequently results are consistent to the in-field values. Moreover, based on the third stage's results, the optimum annual constant T R =3 is identified for Brasov, Romania.
A specific issue both for small hydropower plants and wind turbines refers to the discrepancy between the relatively low speed of the water turbine / wind rotor and relatively high speed of the electric generator: the turbine / rotor has higher performances at lower speeds, while the generator performances are increasing with the speed. Usually, this problem can be solved connecting a proper speed increaser between the turbine and generator. This paper aims to model and simulate a new solving variant for this issue. The solution uses 2 turbines and a generator, connected through a planetary gear with 2 inputs (the turbines) and 1 output (generator). The counter-rotating system functioning is based on the property of the 2 DOF planetary gear sets about summing 2 input motions into an output motion. The transmissions running conditions are modeled in the paper, with examples in relevant applications; the numerical simulation results are comparatively analyzed to those of classical solutions and recommendations concerning their use are settled.
The paper deals with a new variant of a cycloidal planetary transmission (CPT) with modified structure, proposed by the authors, able to accomplish high kinematical ratio and high efficiency, useful to fit mechatronic systems of Renewable Energy Systems (RES). Through the conceptual design approach, six new transmission variants were generated and the principle solution was established. Further on, optimization studies on the geometrical features and dynamic behavior of the new planetary gear were performed. Based on a physical prototype and using a modern high-tech stand, experimental researches on the efficiency of the new cycloidal transmission tested as reducer were performed. The obtained experimental results comply with the theoretical model, and some performance features of the transmission prototype are thus derived. I. INTRODUCTIONA modern trend in developing renewable energy systems (RES) from solar, hydro and wind energy conversion domains deals with the increasing of their energetic efficiency by reducing friction losses. This imposes to use mechatronic transmissions with high efficiency combined with big kinematical (reduction or multiplication) ratio. The paper belongs to this research direction, developing a new solution of cycloid planetary transmissions (CPT) designated to reduce or increase rotational speed with big kinematical ratio, good efficiency and reduced complexity. This new transmission is designated to fit as reducer in certain mechatronic tracking systems (for the solar collectors) and as amplifier in certain hydro and wind mechatronic systems.The tracking systems are mechanical/mechatronic devices meant to orientate the systems for solar energy conversion so that the solar rays propagate perpendicularly on the receptor surface. In the majority of cases, the tracking systems integrate in their actuation a speed reducer with high kinematical ratio [1, 10].Most wind turbines and hydro-power stations' drive trains include a gearbox to increase the speed of the input shaft to the generator. The speed increase is needed because the wind turbines rotors and the hydro turbines shafts turn at a much lower speed than is required by most electrical generators. The range in which the input angular speed must be increased is 3…30 [8, 9, 12].The transmission of mechanical power under a constant kinematical ratio, represents the function of a large class of products known as speed reducers/ amplifiers. The use of these products is imposed mainly by the usual incongruity between the high motor speeds and the relatively reduced speeds of effectors [5,14,17].
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.