scholarly journals Grounding System Modeling and Evaluation Using Integrated Circuit Based Fast Relaxed Vector Fitting Approach, Considering Soil Ionization

2020 ◽  
Vol 10 (16) ◽  
pp. 5632
Author(s):  
Maziyar Fakhraei ◽  
Mehrdad Mahmoudian ◽  
Eduardo Manuel Godinho Rodrigues
Keyword(s):  
Integrated Circuit ◽  
System Modeling ◽  
Model Verification ◽  
Lightning Strikes ◽  
Grounding System ◽  
Vector Fitting ◽  
Grounding Grids ◽  
Electro Magnetic ◽  
Soil Ionization ◽  
System Frequency

Since high voltage transmission line towers or wind turbines structures are installed in high-altitude areas, it is essential to achieve a high overvoltage protection system against direct and indirect lightning strikes collisions. The lightning current must be discharged quickly into the protective earth, to prevent the dangerous over-voltages formation and define a reference voltage node. This paper presents a novel model to assess the behavior of the grounding system, based on Pocklington integral equations under lightning magnetic fields and variations in soil ionization, in which an explicit circuit-based vector fitting RLC admittance branches are proposed. The frequency-dependent behavior of grounding system frequency response and soil ionization effect is modeled in time domain, straightly to implement into the electro-magnetic transient program (EMTP). The model verification contains horizontal, vertical, and their combinations of grounding grids to represent the complete investigations under lightning strikes. The harmonic impedance mathematical formulations and principles are derived based on a rational function, that could be applicable on ground potential rise (GPR) investigation.

Transient Voltages on Grounding Grids buried in Stratified Soils

2020 ◽  
Author(s):  
Anderson Anderson R. J. de Araújo ◽  
Walter L. M. de Azevedo ◽  
José Pissolato Filho ◽  
Jaimis S. L. Colqui ◽  
Sérgio Kurokawa
Keyword(s):  
Power Systems ◽  
Electric Circuit ◽  
Lightning Strikes ◽  
Vector Fitting ◽  
Full Wave ◽  
Vertical Electrode ◽  
Radiation Theory ◽  
Lightning Discharges ◽  
Grounding Grids ◽  
Transient Voltages

Grounding grids (GG) play a fundamental role in the protection of personnel and prevention of damages in equipment during surge transients on substations caused by lightning discharges on power systems. In this context, a precise GG modeling must consider several factors such as the arrangement and the soil compacted in stratified layers. This paper proposes a lumped approach for GG buried in several stratified soils to compute the transient node voltages when subjected to lightning strikes. The vertical and horizontal electrodes are modelled separately by lumped circuit approach. The vertical electrode impedances buried in a stratified soil are computed by the numerical Method of Moments (MoM) in the full-wave electromagnetic software FEKOR , directly in frequency domain, and then, an electric circuit is obtained by the Vector Fitting technique. The horizontal electrodes are modelled based on the electromagnetic radiation theory, where each segment of the electrode can be regarded as a lamental currentcarrying conductor. Lightning currents of fast and slow-front waveforms, are employed in the simulations. Results show that when stratified soils are considered, the differences of the transient voltage peaks, in comparison with the ones calculated for the homogeneous soil is more pronounced as the thickness of soil decreases.

scholarly journals Computation of Lightning Voltage Surges on Tall and Conventional Transmission Towers

2020 ◽  
Author(s):  
Anderson R. J. de Araújo ◽  
Claudiner M. de Seixas ◽  
Bamdad Salarieh ◽  
Sérgio Kurokawa ◽  
Behzad Kordi
Keyword(s):  
Power Systems ◽  
Forest Canopy ◽  
Electric Circuit ◽  
Voltage Response ◽  
Transmission Tower ◽  
Lightning Strikes ◽  
Grounding System ◽  
Vector Fitting ◽  
Transmission Towers ◽  
The Time Domain

Transmission tower modelling is very important to assess the electromagnetic transient caused by lightning strikes in power systems. In this context, conventional tower models are very well studied in the literature. However, there are few studies on tall transmission towers which have been receiving great attention recently due to their own characteristics. Tall transmission towers are built on river crossings and/or over dense forest canopy to reduce environmental impact in these areas. In this paper, the voltage surge caused by an incidentlightning at the top of the conventional and tall towers are determined. For both structures, a lumped electric circuit approximated by Vector Fitting technique is proposed which takes into account the tower-footing grounding system buried in different homogeneous soils. The results show a clear difference in the time domain voltage response for the conventional and tall transmission towers which is more pronounced as the soil resistivity increases and/or the tower becomes taller.

scholarly journals Earth-termination system for onshore wind Turbines.

2020 ◽  
Vol 11 (7-2020) ◽  
pp. 66-72
Author(s):  
Liubov A. Belova ◽  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Lightning Strike ◽  
Lightning Protection ◽  
Protection Measures ◽  
Lightning Strikes ◽  
Grounding System ◽  
Initial Stage ◽  
Wind Turbine Towers ◽  
Surge Protection

The earth-termination system for towers of ground-based wind turbines in addition to protective and functional grounding provides lightning protection grounding, which is especially important since the wind turbine is susceptible to lightning strikes. If insufficient protective measures are taken, the risk of damage to a wind turbine due to a lightning strike increases. Therefore, a well-thought-out built-in grounding system for wind turbine towers is needed, which would function as necessary and guarantee long-term mechanical strength and corrosion resistance. The configuration of grounding systems for wind turbines is discussed in IEC 61400-24, which deals with the topic of lightning protection for wind turbines, including detailed information on the choice of lightning protection measures and surge protection. It is advisable to create a lightning protection concept at the initial stage of planning a wind turbine in order to avoid later costly repairs and retrofitting.

A modeling method of algorithm-hardware based on SysML

2021 ◽  
Author(s):  
Liu Yue ◽  
Zhao Chun ◽  
Zhang Lin
Keyword(s):  
Graphical Models ◽  
Integrated Circuit ◽  
High Speed ◽  
System Modeling ◽  
Modeling Method ◽  
Description Language ◽  
Hardware Description ◽  
Circuit And System ◽  
Graphical System ◽  
Hardware Circuit

In the process of complex product design, modeling in different fields and different disciplines is often involved. Designers often face many different development kits, platforms, and theories, among which significant differences exist. Especially in the process of algorithm-hardware implementation, it is necessary to have mastery of the knowledge including algorithm, hardware, circuit, and system engineering. In this paper, a modeling method of algorithm-hardware based on SysML is proposed to reduce the difficulty of algorithm-hardware modeling. By using the method, the designers who do not know the knowledge of hardware can also easily build the algorithm-hardware model. In this method, a method of graphical system modeling based on SysML is used, where the elements of the algorithm-hardware model are described by SysML graphical models. Then, the SysML graphical models are converted to Very-High-Speed Integrated Circuit Hardware Description Language. At last, a detecting algorithm of random number is complemented by the modeling method in this paper and the simulation results are presented at the conclusion.

Design Methodology of Large-Scale Thermoelectric Generation: A Hierarchical Modeling Approach

2012 ◽  
Vol 4 (4) ◽  
Author(s):  
Min Chen ◽  
Junling Gao ◽  
Zhengdong Kang ◽  
Jianzhong Zhang
Keyword(s):  
Integrated Circuit ◽  
Large Scale ◽  
Hierarchical Modeling ◽  
Waste Heat ◽  
System Modeling ◽  
Electric Circuit ◽  
System Level ◽  
Field Calculation ◽  
Thermoelectric Generation ◽  
Level Model

A thermoelectric generation system (TEGS) used in the practical industry of waste heat recovery consists of the fluidic heat sources, the external load circuitry, and many thermoelectric modules (TEMs) connected as a battery bank. In this paper, a system-level model is proposed to seamlessly integrate the complete fluid-thermal-electric-circuit multiphysics behaviors in a single circuit simulator using electrothermal analogy. First, a quasi one-dimension numerical model for the thermal fluids and their nonuniform temperature distribution as the boundary condition for TEMs is implemented in simulation program with integrated circuit emphasis (SPICE)-compatible environment. Second, the electric field calculation of the device-level model is upgraded to reflect the resistive behaviors of thermoelements, so that the electric connections among spatially distributed TEMs and the load circuitry can be freely combined in the simulation. Third, a hierarchical and TEM-object oriented strategy are developed to make the system modeling as well as the design scalable, flexible, and programmable. To validate the proposed system model, a TEGS, including eight TEMs is constructed. Through comparisons between simulation results and experimental data, the proposed model shows sufficient accuracy so that a straightforward cooptimization of the entire TEGS of large scale can be carried out.

scholarly journals Lightning Performance Evaluation of Italian 150 kV Sub-Transmission Lines

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2142
Author(s):  
Fabio Massimo Gatta ◽  
Alberto Geri ◽  
Stefano Lauria ◽  
Marco Maccioni ◽  
Francesco Palone
Keyword(s):  
Monte Carlo ◽  
Performance Evaluation ◽  
Transmission Lines ◽  
Computational Cost ◽  
Lightning Strikes ◽  
Grounding System ◽  
Monte Carlo Procedure ◽  
Overhead Transmission Lines ◽  
Realistic Assessment ◽  
Low Computational Cost

A significant majority of overhead transmission lines’ (OHLs) outages is due to backflashovers caused by direct lightning strikes: the realistic assessment of the lightning performance is thus an important task. The paper presents the analysis of the lightning performance of an existing 150 kV Italian OHL, namely, its backflashover rate (BFOR), carried out by means of an ATP-EMTP-based Monte Carlo procedure. Among other features, the procedure makes use of a simplified pi-circuit for line towers’ grounding system, allowing a very accurate reproduction of transient behaviours at a very low computational cost. Tower grounding design modifications, aimed at improving the OHL lightning performance, are also proposed and discussed.

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