scholarly journals DEVELOPMENT AND MODELLING OF HIGH SPREAD CONDUCTIVITY EARTH ELECTRODES FOR COMPLEX EARTHING ARRANGEMENTS

Author(s):  
Vyacheslav Balalaiev ◽  
Olena Fedoseenko

The analysis of methods for calculating the electrical characteristics of earth electrodes in case of emergency currents of industrial frequency flowing through the elements of earthing arrangements is carried out. A method for improving complex earthing arrangements of electrical installations by optimization of their design parameters is proposed. The proposed method consists in installing an artificial earth electrode with an increased contact area of its surface with the ground, which makes it possible to increase the conductivity of earthing spreading. The use of these electrodes on the territory of projected or operating electrical installations ensures that the values of the normalized parameters of earthing arrangements are brought to permissible values. The use of the method given in the calculations of earthing arrangements requires the replacement of volumetric earth electrodes with a set of linear vertical electrodes. The design model is substantiated by equivalent electrical characteristics relative to the two-layer model of the electrical structure of the earth. The equivalent model was obtained by a given approximation of the electrical characteristics of a set of straight electrodes in the process of increasing their number to the equivalent characteristics of the reference model. In turn, the determination of the characteristics of the reference model was carried out directly by solving the boundary value problem for the potential satisfying Laplace equation using finite difference method. Theoretical investigations using induced potential method and methods of calculation of branched electric circuits with distributed parameters for calculation of electric field and resistance of the complex non-equipotential earth electrode in the ground with two-layer structure have been carried out. The developed electrodes of increased spread conductivity are mounted as experimental samples and are involved in the formation of the electrical characteristics of the earthing arrangements.

2018 ◽  
Vol 9 ◽  
pp. 155-163 ◽  
Author(s):  
Doina Manaila Maximean ◽  
Octavian Danila ◽  
Pedro L Almeida ◽  
Constantin Paul Ganea

Electro-optical devices that work in a similar fashion as PDLCs (polymer-dispersed liquid crystals), produced from cellulose acetate (CA) electrospun fibers deposited onto indium tin oxide coated glass and a nematic liquid crystal (E7), were studied. CA and the CA/liquid crystal composite were characterized by multiple investigation techniques, such as polarized optical microscopy, dielectric spectroscopy and impedance measurements. Dielectric constant and electric energy loss were studied as a function of frequency and temperature. The activation energy was evaluated and the relaxation time was obtained by fitting the spectra of the dielectric loss with the Havriliak–Negami functions. To determine the electrical characteristics of the studied samples, impedance measurements results were treated using the Cole–Cole diagram and the three-element equivalent model.


2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Ruei-Tang Chen ◽  
Chih-Chieh Kang ◽  
Jeng-Feng Lin ◽  
Sheng-Wei Chiou ◽  
Hung-Hsiang Cheng ◽  
...  

Building integrated photovoltaics (BIPV) are an important application of future solar energy development. The incorporation of solar cells into windows must not only maintain indoor natural lighting but also generate electrical power at the same time. In our continuing effort to improve the design of diffusion solar window, a more fundamental and efficient three-layer structure—glass/EVA with TiO2nanoparticles embedded/glass—was proposed. In this work, a well-established ASAP ray-tracing model for a diffusive solar cell window was implemented to validate the outperformance of three-layer structure over primitive five-layer structure. Optical simulations were also implemented to perform its primary design for the determination of the optimal design parameters, such as the glass thickness, the EVA thickness, and the weight concentration of TiO2nanoparticles. Based on the simulation results, an optimal design for a three-layer diffusive solar cell window prototype was proposed. And the influence of both EVA thickness and glass thickness on the power edge-exitance (solar cell power generation efficiency) of a DSCW was thoroughly investigated.


2017 ◽  
Vol 897 ◽  
pp. 545-548 ◽  
Author(s):  
Sauvik Chowdhury ◽  
Collin W. Hitchcock ◽  
T. Paul Chow

We present a comparative study of the electrical characteristics of different 1200V commercial SiC power MOSFETs at cryogenic temperatures down to 77 K. As compared to conventional silicon power MOSFETs, SiC MOSFETs show very different operating characteristics at low temperatures which is due to unique material and design parameters used in SiC MOSFETs. Of particular interest is a non-linear mixed triode/pentode-like I-V characteristic exhibited by all SiC MOSFETs at 77 K, which is demonstrated to be due to short channel effects in the constituent JFET.


2019 ◽  
Vol 139 ◽  
pp. 01054 ◽  
Author(s):  
M.I. Ibadullaev ◽  
A.N. Tovbaev ◽  
A.Zh. Esenbekov

It is known that the occurrence and existence of autoparametric oscillations (AIC) at the subharmonic frequency (GHC) in power lines (power lines) and in power supply systems is extremely undesirable, since they cause ferroresonant overvoltages at different frequencies. At the same time, there is an extensive class of nonlinear electric circuits in which the excitation of the AIC at the frequency of the SGC forms the basis of frequency-converting devices serving as secondary power sources. It is shown that single-phase-three-phase nonlinear systems are, to one degree or another, equivalent circuits of power lines, the main elements of which are: longitudinal compensation capacitors, transverse compensation reactors, and transformers with non-linear characteristics. The regularities of the excitation of the GCC at the frequency (ω / 3) of the power lines were studied, theoretical and experimental studies of the equivalent model of single-phase-three-phase circuits with nonlinear inductance were carried out. For a theoretical analysis of the steady-state mode of SGK at a frequency (ω / 3) with inductive coupling, the frequency- energy approach is used. The conditions of existence and critical parameters of the circuit are determined, and the mechanism of the appearance of the SGC at the frequency (ω / 3) is also studied.


2020 ◽  
Author(s):  
Fanny Picourlat ◽  
Emmanuel Mouche ◽  
Claude Mugler

<p>Several authors in the literature, such as Khan (2014) and Loritz (2017), have previously suggested that 3D catchment hydrology can be predicted from 2D hillslope simulations. Following this idea, we propose an upscaling methodology for runoff and evapotranspiration fluxes. The first step consists of a geomorphic analysis of the studied watershed. The average mean slope and hillslope length are then used to build a 2D equivalent-hillslope model. The validity of the methodology is tested by comparing the resulting water balance with a 3D physically-based distributed model. 2D fluxes of the equivalent hillslope are converted into 3D by using the drainage density. This upscaling methodology is applied to the Little Washita (LW) watershed (Oklahoma, USA). Both the 3D reference model and the 2D equivalent model are built with the physically-based distributed code HydroGeoSphere, which is forced by LW reanalysis climatic data. Two decades are simulated. Regarding the evapotranspiration, the upscaling methodology with only one equivalent hillslope gives a good prediction of 3D fluxes. However, a combination of several hillslopes is needed for simulating the 3D flow rate at the basin’s outlet. This work on the decrease of model dimensionality is a first step in the upscaling process from 3D physically-based models to 1D column models used in global Land Surface Models.</p>


2014 ◽  
Vol 698 ◽  
pp. 203-208
Author(s):  
Yuliya Pleshivtseva ◽  
Stepan Korshikov ◽  
Evgenjj Makarov

Most high duty parts used in various fields of productions are forged parts made of steel. The conventional forging process chains include an induction heating systems and hot forming equipment. The large amount of consumed energy and an excess of material (flash) are the main factors motivating necessity to optimize the industrial technologies of metal hot forming. A significant economical effect can be achieved through optimization of heating modes and design parameters of induction heaters on the basis of modern optimal control theory for distributed parameters systems. The aim of the presented research is a problem-oriented simulation of induction heating stage in the forging chain. 2D ANSYS model provides FEM analysis of interrelated electromagnetic, temperature and thermal stress fields during induction heating of a steel cylindrical billet before its hot forming. The model has interface adapted to optimization procedures; it provides more options for variation of the heating system parameters or billet geometry and material properties, and for evaluating the process optimization abilities.


Author(s):  
Noah D. Manring

In this paper, the conical-shaped equivalent model for a bolted joint is considered. In particular, the governing equations for this model are made non-dimensional for the purposes of conducting sensitivity analysis. From this work, a plot of the dimensionless spring-rate of the clamped material is generated for all reasonable designs for which the conicalshaped equivalent model applies. The sensitivity analysis is then used to discuss the relative importance of estimating the proper model and design parameters and a maximum percent of uncertainty in the spring-rate calculation is also presented. It is shown in this discussion that the calculations are quite sensitive to a proper estimation of the cone angle (a model parameter) and that uncertainty within this calculation can range from 5 to 20%.


Author(s):  
S. Lakrih ◽  
J. Diouri

AbstractThis paper presents a dynamic equivalent model for transmission network dynamic behavior analysis in MATLAB SIMULINK. The electromagnetic frequency response and electromechanical response are combined in the model. The dynamic behavior of distributed parameters line modeled by the EMTP equivalent model is compared with that corresponding to lumped parameter line represented by π model. The aim is to define the frequency band in which the lumped model can accurately represent the distributed parameters model on no load conditions but also when the network is loaded. The proposed equivalent model is explored to investigate the impact of topology on the network dynamics. Besides, the influence of load nature and compensation rate on the driving point frequency response are analyzed analytically and simulated via the proposed model.


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