Analysis of The Performance of A PV/PCM System in Variable Solar Radiation Conditions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Carlos Armenta-Deu
Keyword(s):  
Steady State ◽  
Melting Point ◽  
Solar Radiation ◽  
Transient State ◽  
Good Method ◽  
Day Length ◽  
System Response ◽  
Time Interval ◽  
Steady State Temperature ◽  
Radiation Conditions

This paper studies the performance of a PV/PCM system operating at variable solar radiation conditions. The system has been tested for six different solar radiation levels, from 250 W/m2 to 950 W/m2 determining the steady-state temperature for every case. An algorithm has been developed to predict the steady-state temperature. This prediction has produced values within 97% accuracy of experimental data. A reduction of temperature up to 18.9ºC has been achieved. An algorithm has been developed to correlate reduction in temperature with solar radiation levels. This algorithm can be combined with the classical expression for the PV panel efficiency resulting in a good method for determining the increase of the efficiency. Additionally, the system has been tested for continuous solar radiation evolution, analyzing the system response under the transient state. The procedure has been conducted for the former six solar radiation levels considering the solar radiation evolves linearly from one value to another during a time interval. The simulation has been tested against outdoor solar radiation with an accuracy higher than 98%. The predicted value of the PCM Temperature at the end of the day as shown matches the melting point of the PCM used in the experiment (55ºC), which has been verified experimentally. Besides, the transient state analysis has given the temperature evolution of the PCM at every interval, resulting in a very good match with experimental tests. The analysis of the transient state that the system reaches the melting point at 1/3 of the solar day length, maintaining the phase change state for the rest of the day. This is in good agreement with the experimental observation.

Kinetic Parameters of Continuous Flow Analysis

1967 ◽  
Vol 13 (6) ◽  
pp. 451-467 ◽  
Author(s):  
R E Thiers ◽  
R R Cole ◽  
W J Kirsch
Keyword(s):  
Steady State ◽  
Kinetic Parameters ◽  
Continuous Flow ◽  
Flow Analysis ◽  
Transient State ◽  
Steady States ◽  
Lag Phase ◽  
Time Interval ◽  
Base Line ◽  
Time Required

Abstract Unlike systems of batch analysis, continuous flow systems possess kinetic parameters. Associated with the steady state are such measurements as noise level and drift. This study reports on kinetic parameters associated with the transient state between the steady states including time required to change from base-line steady state to sample steady state and vice versa, characteristics of this change, time interval between samples, proportionality of sampling and washing time, fraction of steady state reached in any given sampling time, and interaction between samples. The transition between steady states has been found to obey first order kinetics to a good first approximation. This observation enables correlation of all of the above listed properties in quantitative fashion using new characteristic constants for continuous flow-the half-wash time (W1/2) and the lag phase time (L). These parameters, well known in other contexts such as radioactivity, can be employed as "figures of merit" for any continuous flow system or component, can be utilized to calculate performance characteristics, and are useful in evaluating and optimizing over-all performance.

scholarly journals Improvement of MPPT Control Performance Using Fuzzy Control and VGPI in the PV System for Micro Grid

2019 ◽  
Vol 11 (21) ◽  
pp. 5891 ◽  
Author(s):  
Kim ◽  
Huh ◽  
Ko
Keyword(s):  
Steady State ◽  
Solar Radiation ◽  
Fuzzy Control ◽  
Transient State ◽  
Pi Controller ◽  
Maximum Power ◽  
Pv System ◽  
Maximum Power Point ◽  
Pi Controllers ◽  
Power Point

This paper proposes the method for maximum power point tracking (MPPT) of the photovoltaic (PV) system. The conventional PI controller controls the system with fixed gains. Conventional PI controllers with fixed gains cannot satisfy both transient and steady-state. Therefore, to overcome the shortcomings of conventional PI controllers, this paper presents the variable gain proportional integral (VGPI) controllers that control the gain value of PI controllers using fuzzy control. Inputs of fuzzy control used in the VGPI controller are the slope from the voltage-power characteristics of the PV module. This paper designs fuzzy control's membership functions and rule bases using the characteristics that the slope decreases in size, as it approaches the maximum power point and increases as it gets farther. In addition, the gain of the PI controller is adjusted to increase in transient-state and decrease in steady-state in order to improve the error in steady-state and the tracking speed of maximum power point of the PV system. The performance of the VGPI controller has experimented in cases where the solar radiation is constant and the solar radiation varies, to compare with the performance of the P&O method, which is traditionally used most often in MPPT, and the performance of the PI controller, which is used most commonly in the industry field. Finally, the results from the experiment are presented and the results are analyzed.

Effect of Low Temperature on Floral Induction of Eucalyptus lansdowneana F. Muell. & J. Brown subsp. lansdowneana

1992 ◽  
Vol 40 (2) ◽  
pp. 157 ◽  
Author(s):  
MW Moncur
Keyword(s):  
Solar Radiation ◽  
Floral Induction ◽  
Day Length ◽  
Vegetative Development ◽  
Breeding Programs ◽  
Stage Of Development ◽  
High Solar Radiation ◽  
Low Levels ◽  
Radiation Conditions ◽  
Short Days

Transferring seedlings of Eucalyptus lansdowneana from a heated glasshouse (24/19°C) to a cold glasshouse (15/10°C) for 5 or 10 weeks and back to the heated glasshouse was sufficient to induce floral buds. Bud production was further enhanced when seedlings were transferred to cold conditions during periods of high solar radiation. Under low levels of solar radiation and short duration of cold, 0-5 weeks, plants reverted to vegetative development, suggesting a low floral induction stimulus. Seedlings that produced a visible floral inflorescence had fewer leaves than seedlings grown under similar conditions that had not produced an inflorescence. This was more noticeable under high-radiation conditions. Plants grown under outside conditions in Canberra and transferred to a heated glasshouse (25/ 18°C) during winter initiated inflorescences 7-9 weeks earlier than plants grown continuously outside. The early initiation enabled buds to develop and flower before the onset of the following winter. More buds were initiated in plants transferred to the glasshouse in September compared with 16 June or 28 July. Plants transferred on 16 June initiated few buds or none at all. These plants may have been in a juvenile or transitional stage of development, experienced insufficient cold for full induction or been limited by the low winter irradiances. Floral response occurred under both long days (phytotron) and short days under outside conditions in Canberra, suggesting that E. lansdowneana may well be relatively insensitive to day length. These results are discussed in relation to controlled breeding programs which aim to manipulate flowering time and duration to decrease the generation interval.

scholarly journals Identification of DC Thermal Steady-State Differential Inductance of Ferrite Power Inductors

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3854
Author(s):  
Salvatore Musumeci ◽  
Luigi Solimene ◽  
Carlo Stefano Ragusa
Keyword(s):  
Steady State ◽  
Input Voltage ◽  
Switching Frequency ◽  
Ohmic Losses ◽  
Steady State Temperature ◽  
Wide Range ◽  
Average Current ◽  
Power Inductors ◽  
Saturable Inductor ◽  
Thermal Steady State

In this paper, we propose a method for the identification of the differential inductance of saturable ferrite inductors adopted in DC–DC converters, considering the influence of the operating temperature. The inductor temperature rise is caused mainly by its losses, neglecting the heating contribution by the other components forming the converter layout. When the ohmic losses caused by the average current represent the principal portion of the inductor power losses, the steady-state temperature of the component can be related to the average current value. Under this assumption, usual for saturable inductors in DC–DC converters, the presented experimental setup and characterization method allow identifying a DC thermal steady-state differential inductance profile of a ferrite inductor. The curve is obtained from experimental measurements of the inductor voltage and current waveforms, at different average current values, that lead the component to operate from the linear region of the magnetization curve up to the saturation. The obtained inductance profile can be adopted to simulate the current waveform of a saturable inductor in a DC–DC converter, providing accurate results under a wide range of switching frequency, input voltage, duty cycle, and output current values.

scholarly journals Multi-Machine Repairable System with One Unreliable Server and Variable Repair Rate

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1299
Author(s):  
Shengli Lv
Keyword(s):  
Steady State ◽  
Transient State ◽  
Repairable System ◽  
Repair Rate ◽  
Numerical Illustration ◽  
Transform Method ◽  
Unreliable Server ◽  
Busy Time ◽  
The Mean ◽  
Mean Time

This paper analyzed the multi-machine repairable system with one unreliable server and one repairman. The machines may break at any time. One server oversees servicing the machine breakdown. The server may fail at any time with different failure rates in idle time and busy time. One repairman is responsible for repairing the server failure; the repair rate is variable to adapt to whether the machines are all functioning normally or not. All the time distributions are exponential. Using the quasi-birth-death(QBD) process theory, the steady-state availability of the machines, the steady-state availability of the server, and other steady-state indices of the system are given. The transient-state indices of the system, including the reliability of the machines and the reliability of the server, are obtained by solving the transient-state probabilistic differential equations. The Laplace–Stieltjes transform method is used to ascertain the mean time to the first breakdown of the system and the mean time to the first failure of the server. The case analysis and numerical illustration are presented to visualize the effects of the system parameters on various performance indices.

Implementation of a modified P&O-MPPT algorithm adapted for varying solar radiation conditions

2016 ◽  
Vol 99 (3) ◽  
pp. 839-846 ◽  
Author(s):  
Abdelhakim Belkaid ◽  
Ilhami Colak ◽  
Korhan Kayisli
Keyword(s):  
Solar Radiation ◽  
Radiation Conditions
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