Insolation Conditions Research Articles

Correlation between the morphology of unheated staircase and energy performance of residential buildings

As a side effect of the need for greater energy efficiency of buildings, there is a problem of decrease of the available interior space affected by the reduction in U-value of parts of thermal building envelope, i.e. an increase in thickness of insulating layer, which is especially present in unheated staircase. Having in mind that present methods of calculation of transmission heat losses through elements of thermal envelope include the adjustment factor which regulates designed temperature conditions if the temperature at the colder side of the element of the thermal envelope differs from that of the external environment, this paper strives to demonstrate that in the case of unheated staircases, this fixed value should be reconsidered and treated as a variable depending on the morphology, i.e. form, size and position of the staircase within the building. This problem has been analyzed on the example of Serbian housing stock and relevant national thermal regulations. Three morphological types of unheated staircases have been distinguished within which three models have been defined and examined with respect to variations in number of floors and percentage of glazing. Average temperatures of staircase volume and temperature correction factors were calculated in following temperature modes: stationary that excluded solar gains and ventilation heat losses and gains, and dynamic with variations in air exchange rates and insolation conditions, expressing in all of the cases variations in calculated values of temperature correction factors in comparison to the prescribed fixed value.

Design of Incremental Conductance Sliding Mode MPPT Control Applied by Integrated Photovoltaic and Proton Exchange Membrane Fuel Cell System under Various Operating Conditions for BLDC Motor

This paper proposes an integrated photovoltaic (PV) and proton exchange membrane fuel cell (PEMFC) system for continuous energy harvesting under various operating conditions for use with a brushless DC motor. The proposed scheme is based on the incremental conductance (IncCond) algorithm combined with the sliding mode technique. Under changing atmospheric conditions, the energy conversion efficiency of a PV array is very low, leading to significant power losses. Consequently, increasing efficiency by means of maximum power point tracking (MPPT) is particularly important. To manage such a hybrid system, control strategies need to be established to achieve the aim of the distributed system. Firstly, a Matlab/Simulink based model of the PV and PEMFC is developed and validated, as well as the incremental conductance sliding (ICS) MPPT technique; then, different MPPT algorithms are employed to control the PV array under nonuniform temperature and insolation conditions, to study these algorithms effectiveness under various operating conditions. Conventional techniques are easy to implement but produce oscillations at MPP. Compared to these techniques, the proposed technique is more efficient; it produces less oscillation at MPP in the steady state and provides more precise tracking.

Enhanced Energy Output From a PV System Under Partial Shaded Conditions Through Artificial Bee Colony

For the maximum utilization of solar energy, photovoltaic (PV) power generation systems are operated at the maximum power point (MPP) under varying atmospheric conditions, and MPP tracking (MPPT) is generally achieved using several conventional methods. However, when partial shading occurs in a PV system, the resultant powervoltage (PV) curve exhibits multiple peaks and traditional methods that need not guarantee convergence to true MPP always. This paper proposes an artificial bee colony (ABC) algorithm for global MPP (GMPP) tracking under conditions of in-homogenous insolation. The formulation of the problem, application of the ABC algorithm, and the results are analyzed in this paper. The numerical simulations carried out on two different PV configurations under different shading patterns strongly suggest that the proposed method is far superior to existing MPPT alternatives. Experimental results are also provided to validate the new dispensation.

Seasons on Saturn. I. Changes in reflecting characteristics of the atmosphere at 1964–2012

Due to considerable tilting of the equator to the orbital plane, presence of rings and elongation of the orbit around the Sun, Saturn is strongly affected by seasonal changes in the solar radiation influx. Such change of the mode of irradiation of Saturn's atmosphere should affect physical properties and optical characteristics of the cloud cover and/or haze above the clouds of the planet, as well as on the vertical structure of the atmosphere at different latitudes. Once in 14,7 terrestrial years we have the equality of conditions of insolation for both hemispheres, when the planet's rings are visible edge-on to a terrestrial observer. Therefore, these moments are interest for comparative study of possible differences in atmospheric characteristics of the northern and southern hemispheres. In recent years, possibilities for such observations were in 1966, 1980, 1995 and 2009. Using the observational data on the distribution of reflective characteristics of the atmosphere on the visible planetary disk, we have compared the results of calculations in the framework of a two-layer model of Saturn's atmosphere for above moments of equinoxes. It was found that in moments of equinox in 1966, 1980 and 1995 for spring hemisphere, which had just emerged from the rings shadow, the planetary latitudinal belts differ significantly from the other zones by the values of scattering component of the optical thickness τ_c of gas layer above the clouds, the volume concentration of aerosol cloud n, and imaginary part of refractive index n_i of cloud particles. But at the time of the equinox in 2009, in the spring hemisphere the expected changes of reflective and absorptive characteristics – did not happen. There methane absorption remained at the same high level and does not form any high-altitude haze and/or rarefied cloud layer. Because they have the photochemical nature, we can assume an insufficient amount of incoming energy into the atmosphere for the possibility of the formation a photochemical aerosol layer in the lower stratosphere and/or upper troposphere of Saturn.

An Ultrafast Maximum Power Point Setting Scheme for Photovoltaic Arrays Using Model Parameter Identification

Maximum power point tracking (MPPT) for photovoltaic (PV) arrays is essential to optimize conversion efficiency under variable and nonuniform irradiance conditions. Unfortunately, conventional MPPT algorithms such as perturb and observe (P&O), incremental conductance, and current sweep method need to iterate command current or voltage and frequently operate power converters with associated losses. Under partial overcast conditions, tracking the real MPP in multipeakP-IorP-Vcurve model becomes highly challenging, with associated increase in search time and converter operation, leading to unnecessary power being lost in the MPP tracking process. In this paper, the noted drawbacks in MPPT-controlled converters are addressed. In order to separate the search algorithms from converter operation, a model parameter identification approach is presented to estimate insolation conditions of each PV panel and build a real-time overallP-Icurve of PV arrays. Subsequently a simple but effective global MPPT algorithm is proposed to track the MPP in the overallP-Icurve obtained from the identified PV array model, ensuring that the converter works at the MPP. The novel MPPT is ultrafast, resulting in conserved power in the tracking process. Finally, simulations in different scenarios are executed to validate the novel scheme’s effectiveness and advantages.

A Hybrid Maximum Power Point Search Method Using Temperature Measurements in Partial Shading Conditions

Abstract Photovoltaic panels have a non-linear current-voltage characteristics to produce the maximum power at only one point called the maximum power point. In the case of the uniform illumination a single solar panel shows only one maximum power, which is also the global maximum power point. In the case an irregularly illuminated photovoltaic panel many local maxima on the power-voltage curve can be observed and only one of them is the global maximum. The proposed algorithm detects whether a solar panel is in the uniform insolation conditions. Then an appropriate strategy of tracking the maximum power point is taken using a decision algorithm. The proposed method is simulated in the environment created by the authors, which allows to stimulate photovoltaic panels in real conditions of lighting, temperature and shading.

Estimating Hourly Profiles of Insolation based on Weekly Weather Forecast

In this paper, the authors present a simple procedure of estimating weekly profiles of insolation for photovoltaic (PV) power generation output of a roof-top PV system. The model is based on the historical data of solar insolation and weather conditions. Weather conditions are classified into representative patterns such as sunny, cloudy, and rainy, and corresponding hourly profile of insolation is obtained as the most likely values under each weather condition. The system uses the text weather forecast and the probability of precipitation information as input to obtain the estimated weekly profile of insolation. From the results presented here it is shown that such a simple profile can be useful for rating the storage batteries and scheduling electric vehicle charging to better utilize the PV-generated electricity.

Yield loss and quality degradation of strawberry fruits cultivated under the deficient insolation conditions by shading

Deficient insolation conditions (DICs) frequently occur during the winter and early spring season in Korea and negatively affect crop growth. This study was conducted to investigate changes in the yields and qualities of strawberry fruits under DICs that result from an insufficient input of sunlight. To induce DIC, strawberry plants were treated with 40 or 70% shading by covering the plants with curtains during growth in a plastic greenhouse. The shaded plants were cultivated from March to May of 2012. When the strawberry plants were subjected to the shading treatments, their photosynthesis and fruit yields were significantly reduced. Although the mineral element and organic acid contents of the fruits were not affected by the shading treatments, the total nitrogen (T-N) of the stems and roots were noticeably reduced. Furthermore, the shading treatments of the plants also resulted in reductions in the sugar contents and total phenolics of the fruits. In parallel with these observations, the shading treatments were also found to decrease the antioxidant activities of the fruits as measured with the DPPH assay. We suggest that the DIC-induced losses of strawberry fruit yield resulted from the reduced photosynthetic performances of the plants that were caused by insufficient sunlight.

Comparative Analysis on the Performance of a Short String of Series-Connected and Parallel-Connected Photovoltaic Array Under Partial Shading

The output power from the photovoltaic (PV) array decreases and the array exhibit multiple peaks when it is subjected to partial shading (PS). The power loss in the PV array varies with the array configuration, physical location and the shading pattern. This paper compares the relative performance of a PV array consisting of a short string of three PV modules for two different configurations. The mismatch loss, shading loss, fill factor and the power loss due to the failure in tracking of the global maximum power point, of a series string with bypass diodes and short parallel string are analysed using MATLAB/Simulink model. The performance of the system is investigated for three different conditions of solar insolation for the same shading pattern. Results indicate that there is considerable power loss due to shading in a series string during PS than in a parallel string with same number of modules.

MATLAB based modeling to study the performance of different MPPT techniques used for solar PV system under various operating conditions

Abstract Although solar photovoltaic technology is one of the matured technologies, its initial high cost and low efficiency have not made it fully attractive as an alternative option for electricity users. Hence it is very critical to utilize the maximum available solar power of the array and to operate the PV array at its highest energy conversion output. For this, the solar PV generating system has to operate at the maximum power output point. Since the maximum power point varies with radiation and temperature, it is difficult to maintain optimum power operation at all radiation levels. Over the years, many MPPT techniques have been advocated, developed and implemented. These methods vary in several aspects such as complexity, required number of sensors, convergence speed, cost, range of effectiveness, ease of hardware implementation etc. Although different methods have been developed by different research groups, very little literature is available, where different MPPT techniques/methods are compared in terms of energy capture, conversion efficiency, response time and reliability. This paper compares the performance of different MPPT methods that are currently used in a solar PV system and also advocates a new MPPT technique which offers better performance than the existing ones. The methodology adopted for analysis is as follows: Initially, a MATLAB based solar PV array model is first developed and validated; then, different MPPT techniques are employed on this PV array under varying temperature and insolation conditions to study the effectiveness of the particular MPPT technique under consideration.

Estimation of lunar surface temperatures and thermophysical properties: test of a thermal model in preparation of the MERTIS experiment onboard BepiColombo

The Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) is part of the payload on the joint ESA-JAXA BepiColombo Mission, scheduled for launch in 2016. The spectrometer is designed to map surface compositions, to identify rock-forming minerals, to map surface mineralogy, and to study surface temperature variations. In preparation of the experiment we developed a thermal model that calculates surface temperatures based on appropriate insolation conditions and thermophysical properties. In the absence of thermal measurements on Mercury, we validate the model with lunar parameters. The results show good agreement with Apollo 17, Clementine and LRO-Diviner data. With appropriate changes of the orbital parameters and ephemeris data this model can be applied to the conditions of Mercury.

A comprehensive review of maximum power point tracking algorithms for photovoltaic systems

In recent decades, Photovoltaic (PV) energy has made significant progress towards meeting the continuously increasing world energy demand. Besides that, the issue of conventional fossil fuels depletion as well as environmental pollution both contribute to the growth of PV technology. However, the deployment and implementation of photovoltaic systems remain as a great challenge, since the PV material cost is still very high. The low PV module conversion efficiency is another factor that restricts the wide usage of PV systems, therefore a power converter embedded with the capability of maximum power point tracking (MPPT) integrated with PV systems is essential to further the technology. This paper provides a comprehensive review of the available MPPT techniques, both the uniform insolation and partial shaded conditions. In order to appreciate the knowledge of MPPT concepts, several types of PV cell equivalent models are explained too. Conventional MPPT techniques have proven the ability to track the maximum power point (MPP) under uniform solar irradiance. However, under rapidly changing environments and partially shaded conditions, conventional techniques have failed to track the true MPP. For this reason, stochastic based methods and artificial intelligence have been developed with the ability to seek the true MPP under multiple peaks with good convergence speed. This paper analyses and compares both conventional and stochastic MPPT techniques based on the true MPP tracking capability, design complexity, cost consideration, sensitivity to environmental change and convergence speed. Comparatively, the stochastic algorithms and artificial intelligence show excellent tracking performance. The research on MPPT techniques is ongoing towards achieving a better performance in terms of the ease of implementation, low system cost and better tracking efficiency.

A Neural Network Based MPPT Technique Controller for Photovoltaic Pumping System

The article proposes a novel method using the artificial neural network (ANN) for the improvement of the performances of a photovoltaic system composed of a photovoltaic (PV) array, an inverter, a motor asynchronous and a centrifugal pump. For this type of system, different optimization strategies have been proposed to improve the over of the PV system efficiency, i.e. the PV generator is forced to operate at its maximum power point “MPPT”, generally, by the insertion of DC/DC boost converter between the photovoltaic array and the inverter. In this work we propose an approach, where optimization is realized without need adding a DC/DC converter to the chain, using field-oriented control through the monitoring of the voltage-fed inverter frequency. The motor is also ensured in all insolation conditions. A multilayer feed forward perception type NN is proposed for MPPT control, and the back-propagation algorithm is used for training. The performances of the drive with ANN-based MPPT are excellent. The maximum power point (MPP) can be easily obtained to frequency-controlled drive. DOI: http://dx.doi.org/10.11591/ijpeds.v4i2.5875

1P2-N04 影を考慮した月探査ローバの走行経路計画(宇宙ロボット)

This paper presents the influence of shadow on the path planning of lunar rovers. To evaluate the influence of shadow, the terrain and shadow on the Moon are first modeled using the DEM derived from Kaguya data. Subsequently, on the basis of a path planning algorithm considering the shadow, numerical simulation is performed for the lunar terrain. In the simulation, a short path crossing shadow is compared with a long path avoiding shadow under various insolation conditions. The simulation results confirmed that although avoiding shadow adds a traveling distance and time, it doses not much affect the average power consumption but contributes to an increase in the average power generated.

'Niigata S3' is a new strawberry cultivar suitable for forcing culture under low temperature and insolation conditions.

‘Niigata S3’ is a new strawberry (Fragaria × ananassa Duch.) cultivar that is early flowering and possesses high soluble solid content and good coloration. It was selected from a cross between Kei812 (seed parent) and ‘Asuka-Ruby’ (pollen parent). The first harvest date of ‘Niigata S3’ was December 27, 34 days earlier than ‘Echigohime’ and 9 days earlier than ‘Asuka-Ruby’ (means of 2007 and 2008). The marketable yield of ‘Niigata S3’ was 85% of ‘Echigohime’, 107% of ‘Asuka-Ruby’, while the early yield was 145% of ‘Echigohime’, 85% of ‘Asuka-Ruby’ (based on 2007 and 2008 means). The shape of the fruit is long conical, and its skin color medium-red. The fruit skin hardness of ‘Niigata S3’ was 31.5 g/mm2, which was harder than ‘Echigohime’, and its average soluble solid content was 11.4%, which was higher than the values for ‘Echigohime’ and ‘Asuka-Ruby’ (2008). Furthermore, ‘Niigata S3’ did not bear apical overripe fruit. This new cultivar is adaptable to the climatic conditions of Niigata, as well as other regions that experience low winter temperatures and insolation.

Comparison of Perturb & Observe and Fuzzy Logic in Maximum Power Point Tracker for PV Systems

In this paper, an intelligent control method for the maximum power point tracking (MPPT) of a photovoltaic system under variable temperature and insolation conditions is discussed. The MPPT controller for boost converter based on fuzzy logic (FLC) is developed and compared to conventional tracking algorithm (P&O). The different steps of the design of these controllers are presented together with its simulation. Results of this simulation show that the system with MPPT using fuzzy logic controller increase the efficiency of energy production from PV.

Hopfield neural networks approach for design optimization of hybrid power systems with multiple renewable energy sources in a fuzzy environment

The global energy sector faces major challenges in providing sufficient energy to the world's ever increasing energy demand. Methods to produce a greener, cost effective and reliable source of alternative energy needs to be explored and exploited. One of those methods is done by integrating or hybridizing multiple different alternative energy sources e.g. wind turbine generators, photovoltaic cell panels and fuel-fired generators, equipped with storage batteries to form a distributed generation DG power system. However, even with DG power systems, cost effectiveness, reliability and pollutant emissions are still major issues that need to be resolved. The model development and optimization of the DG power system was carried out successfully in the previous work using Particle Swarm Optimization PSO. The goal was to minimize cost, maximize reliability and minimize emissions multi-objective subject to the requirements of the power balance and design constraints. In this work, due to the uncertain nature on the weather conditions, the power output from the PV cells, WTG and the storage batteries which are subject to insolation and wind conditions were fuzzified in an effort to create a more realistic model. The optimization in a fuzzy environment was then performed by using Hopfield neural network HNN. The optimized results were then discussed and analyzed.

Maximum Power Point Tracking Control Using Neural Networks for Stand-Alone Photovoltaic Systems

The employment of maximum power point tracking techniques in the photovoltaic power systems is well known and even of immense importance. There are various techniques to track the maximum power point reported in several literatures. In such context, there is an increasing interest in developing a more appropriate and effective maximum power point tracking control methodology to ensure that the photovoltaic arrays guarantee as much of their available output power as possible to the load for any temperature and solar radiation levels. In this paper, theoretical details of the work, carried out to develop and implement a maximum power point tracking controller using neural networks for a stand-alone photovoltaic system, are presented. Attention has been also paid to the command of the power converter to achieve maximum power point tracking. Simulations results, using Matlab/Simulink software, presented for this approach under rapid variation of insolation and temperature conditions, confirm the effectiveness of the proposed method both in terms of efficiency and fast response time. Negligible oscillations around the maximum power point and easy implementation are the main advantages of the proposed maximum power point tracking (MPPT) control method.

An Improved PSO-Based MPPT Control Strategy for Photovoltaic Systems

This paper presents a control strategy proposed for power maximizing which is a critical mechanism to ensure power track is maximized. Many tracking algorithms have been proposed for this purpose. One of the more commonly used techniques is the incremental conductance method. In this paper, an improved particle swarm optimization- (IPSO-) based MPPT technique for photovoltaic system operating under varying environmental conditions is proposed. The approach of linearly decreasing scheme for weighting factor and cognitive and social parameter is modified. The proposed control scheme can overcome deficiency and accelerate convergence of the IPSO-based MPPT algorithm. The approach is not only capable of tracking the maximum power point under uniform insolation state, but also able to find the maximum power point under fast changing nonuniform insolation conditions. The photovoltaic systematic process with control schemes is created using MATLAB Simulink to verify the effectiveness with several simulations being carried out and then compared with the conventional incremental conductance technique. Lastly, the effectiveness of the intended techniques is proven using real data obtained form previous literature. With the change in insolation and temperature portrait, it produces exceptional MPPT maximization. This shows that optimum performance is achieved using the intended method compared to the typical method.

Development of Empirical Equations for Irradiance Profile of a Standard Parabolic Trough Collector Using Monte Carlo Ray Tracing Technique

This article explains a technique in which equations are developed to produce the irradiance profile around the receiver of LS2 collector using a vigorouslyverified MCRT model. A large range of test conditions including daily normal insolation, selective coatings and glass envelop conditions were chosen from the published data by Dudley et al. [1] for the job. The R2value is excellent that varies between 0.9857 and 0.9999. Therefore, these equations can be used confidently to produce boundary heat flux profile of the collector at normal incident for conjugate heat transfer analyses of the receiver.