Variability of Performance Indices of Photovoltaic Solar Panels in Operating Conditions in the Littoral Zone of Cameroon

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of computational fluid dynamics (CFD) simulations, based on the numerical solution of the Navier–Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth, and texture density on the bearing performance indices (load carrying capacity, friction torque, and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

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A STUDY ON PREVALENT FACTORS BEHIND EFFICIENCY DETERIORATION OF A TYPICAL LOW POWER SOLAR PANEL

International Symposium on Microelectronics ◽

10.4071/isom-2013-tp57 ◽

2013 ◽

Vol 2013 (1) ◽

pp. 000384-000388

Author(s):

V. Ganescu ◽

A. Pascu

Keyword(s):

Low Power ◽

Operating Conditions ◽

Extreme Temperatures ◽

Solar Panels ◽

Cycle Number ◽

Solar Noon ◽

Operation Duration ◽

Outdoor Behavior ◽

Duration Of Operation ◽

Daylight Exposure

Efficiencies for a number of different low power (10W MAX) consumer grade PV solar panels were studied in this research. Outdoor behavior was contrasted with lab environment simulations. The authors focused on four parameters: extreme temperatures of operation, duration of operation per “on” cycle, number of “on – off” cycles and overall period of “on” operation for a 365 days interval. Standard environmental operating conditions were taken into account for the lab environment, where constant solar noon was simulated for 70% of the equivalent daylight exposure time. No CPV or lenses were used. Additionally, a comparison surrounding the estimated life expectancy and efficiency decrease pattern of the panels was targeted and presented in this study.

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Eigenvalue Assignments in Multimachine Power Systems using Multi-Objective PSO Algorithm

International Journal of Energy Optimization and Engineering ◽

10.4018/ijeoe.2015070103 ◽

2015 ◽

Vol 4 (3) ◽

pp. 33-48 ◽

Cited By ~ 3

Author(s):

Yosra Welhazi ◽

Tawfik Guesmi ◽

Hsan Hadj Abdallah

Keyword(s):

Power Systems ◽

Optimal Parameter ◽

Pso Algorithm ◽

Operating Conditions ◽

Performance Indices ◽

Power System Stabilizers ◽

Nonlinear Simulation ◽

Multi Objective ◽

Electromechanical Modes ◽

Wide Range

Applying multi-objective particle swarm optimization (MOPSO) algorithm to multi-objective design of multimachine power system stabilizers (PSSs) is presented in this paper. The proposed approach is based on MOPSO algorithm to search for optimal parameter settings of PSS for a wide range of operating conditions. Moreover, a fuzzy set theory is developed to extract the best compromise solution. The stabilizers are selected using MOPSO to shift the lightly damped and undamped electromechanical modes to a prescribed zone in the s-plane. The problem of tuning the stabilizer parameters is converted to an optimization problem with eigenvalue-based multi-objective function. The performance of the proposed approach is investigated for a three-machine nine-bus system under different operating conditions. The effectiveness of the proposed approach in damping the electromechanical modes and enhancing greatly the dynamic stability is confirmed through eigenvalue analysis, nonlinear simulation results and some performance indices over a wide range of loading conditions.

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Changes of Insulation Properties of Photovoltaic Cables Caused by Ageing Treatment

Transactions on Electrical Engineering ◽

10.14311/tee.2017.1.006 ◽

2020 ◽

Vol 6 (1) ◽

pp. 6-9 ◽

Cited By ~ 1

Author(s):

Juraj Packa ◽

Vladimir Kujan ◽

Daniel Štrkula ◽

Vladimír Šály ◽

Milan Perný

Keyword(s):

Power Plants ◽

Real Life ◽

Life Time ◽

Operating Conditions ◽

Solar Panels ◽

Font Size ◽

Long Term Stability ◽

Cable Systems

<span style="font-family: 'Times New Roman',serif; font-size: 10pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US">An important part of the photovoltaic power plants are cable systems. The dielectric properties of cables, reliability and durability depend on quality of production processes, operating conditions and degradation factors, as well. Expected lifetime of cable systems is more than 20-30 years in general. Their failure free operation and long-term stability of properties has a direct impact on the economic return of the investments. According to our experiences the tests in compliance with valid standards are not adequate to verify real life time during operation. Photovoltaic cables intended for use in outdoor applications for the connection between the solar panels and possible connection between panels and inverter were chosen for our experiments. <span style="-ms-layout-grid-mode: line;">The changes </span>of insulation resistance and breakdown voltage caused by some degradation factors, mainly water, are presented. This research was inspired by real failure in operation.</span>

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CFD Thermohydrodynamic Analysis of 3-D Sector-Pad Thrust Bearings With Rectangular Dimples

Volume 7B: Structures and Dynamics ◽

10.1115/gt2013-94043 ◽

2013 ◽

Cited By ~ 1

Author(s):

C. I. Papadopoulos ◽

L. Kaiktsis ◽

M. Fillon

Keyword(s):

Carrying Capacity ◽

Thermal Effects ◽

Computational Study ◽

Load Capacity ◽

Operating Conditions ◽

Load Carrying Capacity ◽

Performance Indices ◽

Thrust Bearings ◽

Load Carrying ◽

Texture Design

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of Computational Fluid Dynamics (CFD) simulations, based on the numerical solution of the Navier-Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth and texture density on the bearing performance indices (load carrying capacity, friction torque and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

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Analysis and Synthesis of Control Systems for Spacecraft Solar Arrays

Machines ◽

10.3390/machines8040064 ◽

2020 ◽

Vol 8 (4) ◽

pp. 64

Author(s):

Anatoly K. Tishchenko ◽

Eugeny M. Vasiljev ◽

Artyom O. Tishchenko

Keyword(s):

Control System ◽

Power Supply ◽

Pulse Width Modulation ◽

Simulation Models ◽

Operating Conditions ◽

Solar Panel ◽

Hierarchical Organization ◽

Solar Panels ◽

Solar Arrays ◽

Reliable Power Supply

The paper is devoted to the problem of creating highly reliable power supply systems for spacecrafts intended for long-term autonomous flights. Within its framework, the problem of synthesizing a control system for solar arrays is being solved. To solve this problem, a mathematical model of a solar panel was compiled, and a study of its static and dynamic characteristics was carried out. It was found that when the solar panel is controlled using a shunt switch with pulse-width modulation, resonance phenomena appear in the system, leading to an unacceptable change in the polarity of voltages on the photocells. The operating conditions of the solar panels, which exclude the occurrence of the indicated alternating voltages, are found, and appropriate recommendations are given for the choice of the quantization frequency in the system. On the basis of the recommendations received, the transition to a quasi-continuous representation of the control system was carried out, and a graphic-analytical synthesis of the controller providing the required quality indicators of the system was carried out. To ensure the survivability of the power supply system, a method is proposed for the hierarchical organization of the interaction of solar panels, which reproduces the homeostatic properties of biological structures in the system. This property is provided by automatic transfer of control to subsequent levels of the hierarchy as the energy resources of the previous levels are exhausted. In addition, selective control is applied only to that part of the total generated power, which is sufficient to counter the current disturbing influences on the system. This approach to control prevents cascading failures in the system. The paper presents simulation models on which all theoretical positions and methods proposed in the work are tested.

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Recent Meta-heuristic Algorithms with a Novel Premature Covergence Method for Determining the Parameters of PV Cells and Modules

Electronics ◽

10.3390/electronics10151846 ◽

2021 ◽

Vol 10 (15) ◽

pp. 1846

Author(s):

Mohamed Abdel-Basset ◽

Reda Mohamed ◽

Mohamed Abouhawwash ◽

Yunyoung Nam ◽

Attia El-Fergany

Keyword(s):

Heuristic Algorithms ◽

Operating Conditions ◽

Solar Panels ◽

Current Position ◽

Unknown Parameters ◽

Trade Off ◽

Si Solar Cell ◽

Pv Modules ◽

Different Types ◽

Convergence Method

Currently, the incorporation of solar panels in many applications is a booming trend, which necessitates accurate simulations and analysis of their performance under different operating conditions for further decision making. In this paper, various optimization algorithms are addressed comprehensively through a comparative study and further discussions for extracting the unknown parameters. Efficient use of the iterations within the optimization process may help meta-heuristic algorithms in accelerating convergence plus attaining better accuracy for the final outcome. In this paper, a method, namely, the premature convergence method (PCM), is proposed to boost the convergence of meta-heuristic algorithms with significant improvement in their accuracies. PCM is based on updating the current position around the best-so-far solution with two-step sizes: the first is based on the distance between two individuals selected randomly from the population to encourage the exploration capability, and the second is based on the distance between the current position and the best-so-far solution to promote exploitation. In addition, PCM uses a weight variable, known also as a controlling factor, as a trade-off between the two-step sizes. The proposed method is integrated with three well-known meta-heuristic algorithms to observe its efficacy for estimating efficiently and effectively the unknown parameters of the single diode model (SDM). In addition, an RTC France Si solar cell, and three PV modules, namely, Photowatt-PWP201, Ultra 85-P, and STM6-40/36, are investigated with the improved algorithms and selected standard approaches to compare their performances in estimating the unknown parameters for those different types of PV cells and modules. The experimental results point out the efficacy of the PCM in accelerating the convergence speed with improved final outcomes.

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DEVELOPMENT OF MEASURES TO IMPROVE THE OPERATIONAL EFFICIENCY OF AUTONOMOUS LIGHTING COMPLEXES FOR UKRAINIAN HIGHWAYS

Bulletin of the National Technical University "KhPI". Series: Energy: Reliability and Energy Efficiency ◽

10.20998/2224-0349.2020.01.06 ◽

2020 ◽

pp. 38-45

Author(s):

O. М. Dovgalyuk ◽

R. V. Bondarenko ◽

I. S. Yakovenko

Keyword(s):

Renewable Energy ◽

Power Supply ◽

Renewable Energy Sources ◽

Rapid Development ◽

Operational Efficiency ◽

Operating Conditions ◽

Solar Panels ◽

Power Sources ◽

Ambient Temperatures ◽

Lighting Systems

Reducing highway hazards through the creation of modern lighting systems is an important practical task that currently has some difficulties. The rapid development of renewable energy makes it possible to use off-the-shelf solutions to create autonomous lighting complexes for unregulated pedestrian crossings. The analysis of peculiarities of design, constructive structure and operation of autonomous lighting complexes, which are located in Kharkiv region and use renewable energy sources and energy storage systems to power lighting devices and flashing signal lights, is carried out. The analysis results showed that the lighting complexes under investigation are not capable of supplying sufficient energy for themselves and of functioning properly at low insolation and low ambient temperatures. The reasons for the unstable operation of autonomous lighting complexes have been identified, with the main one being the insufficient accuracy of taking into account the actual climatic operating conditions of facilities when forming design solutions. Measures have been developed to improve the efficiency of the autonomous lighting complexes under study, involving the use of off-the-shelf technical solutions based on modern tools and technologies. A criterion for sufficiency of the developed measures to solve the problem of autonomous power supply of lighting complexes for highways is proposed. The sign of the resulting capacity of the complex over the calculation time period is taken as a sufficiency criterion. The practical use of the developed criterion confirmed the feasibility of the proposed measures to improve the operational efficiency of the investigated autonomous lighting complexes for highways. Calculations have shown that it is not sufficient to use solar panels alone to supply highway lighting complexes located in regions with unstable levels of insolation. The feasibility of hybrid power supply systems for autonomous lighting complexes that use additional power sources such as wind turbines and systems with electromechanical converters in addition to solar panels has been quantitatively confirmed.

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Accurate Maximum Power Tracking in Photovoltaic Systems Affected by Partial Shading

International Journal of Photoenergy ◽

10.1155/2015/824832 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 24

Author(s):

Pierluigi Guerriero ◽

Fabio Di Napoli ◽

Vincenzo d’Alessandro ◽

Santolo Daliento

Keyword(s):

Operating Conditions ◽

Maximum Power ◽

Absolute Maximum ◽

Solar Panels ◽

Partial Shading ◽

Local Maxima ◽

Maximum Power Tracking ◽

The Absolute ◽

Power Point ◽

Solar Field

A maximum power tracking algorithm exploiting operating point information gained on individual solar panels is presented. The proposed algorithm recognizes the presence of multiple local maxima in the power voltage curve of a shaded solar field and evaluates the coordinated of the absolute maximum. The effectiveness of the proposed approach is evidenced by means of circuit level simulation and experimental results. Experiments evidenced that, in comparison with a standard perturb and observe algorithm, we achieve faster convergence in normal operating conditions (when the solar field is uniformly illuminated) and we accurately locate the absolute maximum power point in partial shading conditions, thus avoiding the convergence on local maxima.

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Improving Heat Transfer from Peltier Devices Used in an Atmospheric Water Generation

International Journal of Engineering Materials and Manufacture ◽

10.26776/ijemm.06.03.2021.08 ◽

2021 ◽

Vol 6 (3) ◽

pp. 170-175

Author(s):

Mark Summers ◽

Bahram Asiabanpour

Keyword(s):

Heat Transfer ◽

Convection Heat Transfer ◽

Operating Conditions ◽

Coefficient Of Performance ◽

Conductive Heat ◽

Vapor Compression ◽

Solar Panels ◽

Atmospheric Water ◽

Thermoelectric Coolers ◽

Phase Change Heat Transfer

Present Atmospheric Water Generation (AWG) systems are useful for providing water in areas with limited water supplies. Many industrial AWG systems use VCR (vapor-compression refrigeration) to achieve a large amount of cooling to extract liquid water out of the air. These systems require large amounts of energy to operate, usually in the form of diesel or AC-powered generators. The systems also have many moving parts that require maintenance and use refrigerants that can leak and cause problems with the environment. An alternative AWG solution is to use DC-powered Peltier devices (thermoelectric coolers) to reduce the temperature of condensation plates to extract water from the air. This solution eliminates the issues with traditional industrial AWG systems since the Peltier devices are solid-state, have very long mean-time between failure (MTBF) performance, and can be powered by solar panels that eliminate the need to burn hydrocarbon-based fuels or have access to a reliable power grid. Also eliminated is the need to use chlorofluorocarbon (CFC) or hydrochlorofluorocarbons (HCFC) refrigerants that have been shown to deplete the ozone layer. This paper will present methods to improve the efficiency of the thermoelectric coolers by more efficiently extracting heat from the hot side of the device. This efficiency will be quantified by evaluating the coefficient of performance (COP) of the thermoelectric cooler under the various operating conditions. Different combinations of conductive heat transfer using aluminium heatsinks, convection heat transfer using forced airflow, and phase change heat transfer using copper heat pipes filled with distilled water will be investigated and evaluated.

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