Line Charge Research Articles

Hybrid intelligence approach for multi-load level reactive power planning using VAR compensator in power transmission network

This paper formulates and solves a techno-economic planning problem of reactive power (VAR) in power transmission systems under loadings. The objective of the proposed research work is to minimize the combination of installation cost of reactive power sources, power losses and operational cost while satisfying technical constraints. Initially, the positions for the placement of reactive power sources are determined technically. Different cost components such as VAR generation cost, line charging cost etc. are then added in the total operating cost in a most economical way. Finally, the optimal parameter setting subjected to reactive power planning (RPP) is obtained by taking advantages of hybrid soft computing techniques. For the justification of the efficiency and efficacy of the proposed approach the entire work is simulated on two inter-regional transmission networks. To validate the robustness and ease of the soft computing techniques in RPP the responses of benchmark functions and statistical proof are provided simultaneously.

Evaluation of electron currents from cesium-coated tungsten emitter arrays with inclusion of space charge effects, workfunction changes, and screening

Evaluations of electron current output from tungsten emitter arrays with Cs and CsI coatings are carried out. The approach is based on first-principles calculations of the material physics including evaluation of the internal potentials, electronic wavefunctions, tunneling probabilities, and work function to predict field emission currents. This is coupled to time-dependent kinetic simulations for the assessment of emitter array currents with an inclusion of many-body Coulomb contributions from the electron swarm, geometric field enhancements with shielding based on a line charge model and dynamic screening from the swarm. Our numerical evaluations for arrays with a hexagonal lattice show the expected role of field screening with reductions in emitter separation. For scaling with emitter number, the results indicate nearest neighbor separations of more than 2.5 times the emitter height, in keeping with previous reports.

Low-impedance high-power pulsed generator based on forming line with built-in Tesla transformer.

In order to meet the application needs of gyromagnetic nonlinear transmission lines, a pulsed power generator is required to output short duration pulses with a fast rising edge in high repetitive-rate mode. In this paper, a low-impedance high-power pulsed generator based on the forming line with a built-in Tesla transformer is explored and developed. The generator includes a 14 Ω coaxial forming line, a SF6/N2 gas switch, and a resistive dummy load, which can steadily operate in 100Hz mode and suits the needs above. The pulsed forming line adopts transformer oil as the insulation medium and has a large shell radius and short length to reduce impedance. It has been verified by CST simulation that a relatively high coupling coefficient (0.93) can be achieved when the length-radius ratio is 3.2. The maximum forming line charging voltage is -600 kV in single-shot mode, while the charging voltage is -520 kV in repetitive-rate mode. The output pulse duration is 13ns with a 4ns rising edge, and its amplitude for a 10 Ω load is -220 kV at a repetition rate of 100Hz. The experimental results showed the feasibility of the low-impedance nanosecond periodically pulsed generator based on an oil forming line charged from the high-coupling Tesla transformer. These efforts expand the technical route of the pulse forming line with a built-in Tesla transformer and set a good foundation for its application in the future.

Current‐voltage model of a graphene nanoribbon p‐n junction and Schottky junction diode

This work presents a simplified analytical model of a p-n junction diode based on a graphene nanoribbon (GNR) and a unique type of Schottky diode based on metallic graphene and semi-conducting GNRs. Due to the one-dimensional nature of GNRs, their electrostatic analyses need to be quite different from that of bulk devices. Two approaches have been taken to model the charge distribution in this depletion region, namely, the point charge approximation for the GNR p-n junction diode and the line charge approximation for the graphene/GNR Schottky diode. Analytical expressions for the spatial distribution of electric field and potential have been derived and the results are quite distinct from their bulk counterparts. The current-voltage relation of each diode has been investigated within the approximation of Shockley's law of junctions. The width dependency of the currents for these diodes has also been modelled and it has been found that the current density of both the diodes decreases with decreasing width. Such an analysis can encourage the modelling of next-generation GNR-based high-speed electronic devices.

How far away is infinity? An electromagnetics exercise to develop intuition regarding models

The estimation of the electric field in simple situations provides an opportunity to develop intuition about the models used in physics. We propose an activity aimed at university students where the electric field of a finite line of charge is compared, analytically or numerically, with the fields of an infinite line and of a point charge. Contrary to intuition, it is not necessary to get very close for the line charge to be considered infinite, nor to move very far away for the finite line field to resemble that of a point charge. We conducted this activity with a group of students and found that many of them have not yet developed an adequate intuition about the approximations used in electromagnetism.

Techno‐Economic Model for Reactive Power Planning Using Series‐Shunt Compensation Devices Under Load Demand in Power Transmission Network

This research article proposes a planning strategy of reactive power (VAR) in a power transmission system, because reactive power planning (RPP) is a topical issue in the energy sector. Basically, it is a qualitative effort to understand the mathematical principles, technical facets, and economic aspects with their utility in RPP prior to executing the proposed strategy through a unique solution model. Initially, the objective is formulated by measuring different cost components, such as VAR generation cost, line charging cost, flexible AC transmission system (FACTS) device operation cost, and cost due to real power loss. The vulnerable positions in the system are defined for the placement of FACTS devices after computing a set of mathematical methods. The installation bottlenecks of these devices are wiped out depending on some technical considerations and performances. Thereafter, a hybrid intelligence approach along with fundamental algorithms is applied to determine an optimal set of controlling variables in conjunction with active and VAR demand. The code profiling of the proposed approach is rendered on two interregional practical power networks. Finally, the responses of the benchmark functions and statistical outcomes are analyzed extensively to justify the trustworthiness of the proposed solution model.

Boundary influence on the fields and arrangement of the needle domains in barium titanate single crystals

The superposition theory is adopted to study the boundary value problem of needle domains in barium titanate single crystals, which decomposes into an infinite-medium solution and a complementary solution. The model of an equivalent edge dislocation and line charge is adopted to calculate the fields due to the discrete needle domains in an infinite medium. The complementary solutions are obtained from a linear elastic boundary value problem using the finite element method. The influence of boundaries on the fields and arrangement of the needles in thin barium titanate single crystals is analysed, by considering traction-free boundaries and using the plane stress approximation. According to the principle of minimum potential energy, it is found that pairs of parallel needle domains can be stabilized if the effective charge associated with the needle tips is reduced to 48% of the material’s full polarization charge. The evolution of comb-like arrays of needle domains under compressive mechanical load is simulated, and the results are found to be qualitatively similar to experimental observations which have not previously been explained theoretically.

Approximate universality in the tunneling potential for curved field emitters—A line charge model approach

Field emission tips with an apex radius of curvature below 100 nm are not adequately described by the standard theoretical models based on the Fowler–Nordheim and Murphy–Good formalisms. This is due to the breakdown of the “constant electric field” assumption within the tunneling region leading to substantial errors in current predictions. A uniformly applicable curvature-corrected field emission theory requires that the tunneling potential is approximately universal irrespective of the emitter shape. Using the line charge model, it is established analytically that smooth generic emitter tips approximately follow this universal trend when the anode is far away. This is verified using COMSOL for various emitter shapes including the locally non-parabolic “hemisphere on a cylindrical post.” It is also found numerically that the curvature-corrected tunneling potential provides an adequate approximation when the anode is in close proximity as well as in the presence of other emitters.

Many-particle based evaluations for maximum current output from bimodal electron emitter arrays

Evaluations of the current output from emitter arrays have been carried out based on time-dependent kinetic simulations that include many-body Coulombic contributions from the electron swarm, geometric field enhancements with shielding based on a line charge model, and dynamic screening due to the evolution of the swarm in the position and velocity space. Numerical evaluations are applied to different multi-emitter array arrangements having a hexagonal lattice, with a focus on bimodal distributions. Our results show the expected role of field screening with reductions in emitter separation and positional dependence within the array based on connectivity. Different patterns were examined within a hexagonal lattice structure. For a bimodal distribution, output current optimization is shown for alternating arrangements with three or more successive emitters of the same length along primitive axes predicted to have an advantage.

Fourier Enhanced Charge Simulation Method for Electrostatic Analysis of Overhead Transmission Lines

A computationally efficient charge simulation method is developed for three-dimensional electrostatic calculations involving parallel high voltage transmission conductors near a cloud of point charges. The conductors are modeled using axial line charge density segments, each with linearly varying charge density. A typical problem involves solving for the line charge densities and point charge values given the system geometry and voltage boundary conditions. The method was developed to support ongoing research into high voltage transmission line optimization using the external electric field to link transmission capacity and switching impulse flashover. The method uses superposition and applies Fourier principles to reduce computational burden by moving portions of the problem to the spatial frequency domain. Computation time can be significantly reduced relative to an all-spatial charge simulation approach. Examples involving bundled transmission conductors show measured computation time improvement and compare space potential and electric field results to those obtained from finite element analysis.

Calculation of the wake due to radiation and space charge forces in relativistic beams

Radiation reaction force in a relativistic beam, also known as the CSR wakefield, is often computed using a 1D model of a line charge. While this model can serve as a useful tool for a quick calculation, in many cases its accuracy is not sufficient. In particular, this model misses the so-called compression effects associated with the change of the electromagnetic energy when the beam is compressed longitudinally or transversely. The existing 3D simulation codes that take this effect into account are often slow and are not easy to use. In this work, we propose a new approach to the calculations of radiation and space charge longitudinal forces in free space based on the use of the integrals for the retarded potentials. Our main result expresses the rate of change of particles' energy through 2D (in a 2D model) or 3D integrals along the beam orbit.

The 2D Debye length: An analytical study of weak charge screening in 2D semiconductors

Simple perturbations (such as a line charge or a sheet charge) in 2D semiconducting materials create difficult solutions to the Poisson equation due to the non-uniform out-of-plane electric fields that result from the perturbative charge. Here, for the first time, we determine simple and general analytical expressions for the potential profile, its Fourier representation, the corresponding 2D Debye screening length, and the charge screening behavior in 2D semiconductors due to a line charge perturbation. In contrast to conventional 3D semiconductors, we find that the 2D Debye length goes as 1/ND,2D, where ND,2D is the 2D semiconductor doping density, and this leads to markedly different Debye lengths as compared to those determined by the conventional (3D) Debye length expression. We show that the potential profile due to a charge perturbation in a 2D semiconductor does not decay exponentially with distance from the perturbation (as is the case for 3D semiconductors) but instead decays logarithmically in the immediate vicinity of the perturbation and as 1/x2 when the distance is approximately equal to or greater than the 2D Debye length. Overall, this work establishes an analytical approach for determining a fundamental electrostatic parameter for 2D semiconductors.

Protection of Impact Electromagnetic Radiation on Public Health and Environment, Indonesia

A penetration of SUTET trajectory in residential areas, causing public health problems and environmental problems. Development of the electrical energy sector, regulation the increasing electricity demand. Distribution electricity from inter-GI generating centers requires SUTET in the air with a voltage above 245kV. The community assesses health impact that operates mostly with the voltage of 500 kV, >1000mA/m2, can cause heart problems, extrasystole rhythms, and ventricular fibrillation Electrical sensitivity. A simple method and integrating the divergence shift flux density a radiation point, a method proposed from Strokes theorem relates the closed line integral vector field to curl surface integral and divergence theorem which relates the surface integral a closed vector field to integral volume and divergence vector field, this experiment electric field produced by the line charge is directed radially away from the line charge, so the direction lines electric field(E), and equipotential surfaces perpendicular to each other. This study is a collection of symptoms hypersensitivity, comprehensively, and a potential difference between two points in the electric field, which has the performance of charge unity in responding to charge from both points the area, the solution is environmental-based management. Ionizing radiation is the dispersion or emission energy when through a medium, absorption process occurs, and radiation energy beam does not induce, results in vector potential having magnitude is inversely proportional the radial distance from the element which is similar to inverse distance dependence scalar potential. In conclusion, take steps to empower the community for residents in the area SUTET.

Three-dimensional mapping of two coincident flashes - An upward positive flash triggered by the in-cloud activity of a downward negative flash

Lightning mapping with radio frequency location systems plays a more and more important role in understanding the mechanism of lightning discharges during thunderstorms. Here we present a comprehensive analysis of the electromagnetic field measurements and 3-dimensional (3D) mapping of two coincident lightning flashes: an upward positive flash (+CG) with long preceding upward negative leader (UNL), which was triggered by the in-cloud (IC) activity of a nearby downward negative flash (−CG). The flashes were mapped with a low frequency (LF) mapping array deployed near Duke University and during a late-spring thunderstorm passing a plain area. The 3D LF maps show that the IC activity related to the −CG moved negative charge away from the location overhead the UNL. The UNL developed firstly upward for about 2 km and then extended horizontally for about 8 km at that height with a mean speed of 6.2 × 105 m/s. The channel line charge density of the UNL was estimated to range from −542 μC/m to −9.21 mC/m with a mean value of −3.46 mC/m. The total positive charge transferred from the cloud to ground by the +CG flash was estimated to be about 5.8C. From the 3D maps, we inferred that the IC activity relating to the −CG flash which moved negative charge away from overhead region of the UNL could be responsible for the UNL initiation. And the existence of extensive lower positive charges further favored the long horizontal propagation of the UNL inside the cloud.

Low power SRAM using Adiabatic Logic

In this paper the design of low power SRAM has been presented. SRAM memory cell has been realized using adiabatic logic to achieve low power operation. Adiabatic SRAM has been realized using two methods such as i) gradual charging and discharging of bit-line during writing mode and ii) utilizing control transistor based adiabatic circuit i.e., Two Phase Adiabatic Dynamic Logic (2PADL) circuit for the design of memory cell. Furthermore, energy recovery of word line and bit line charge stored in the interconnect capacitances has been realized for the benefit of energy savings. Charge recovery circuits based on 2PADL has been employed in the proposed SRAM memory core to achieve energy recovery. SRAM memory array of (4×4) has been designed as a test circuit. All the circuits are implemented using 180nm CMOS technology and simulations are carried out using Cadence® Virtuoso tool. Simulation results prove that the proposed memory cell has significant amount of energy savings when compared to the conventional static CMOS SRAM cell.

Optimal reactive power planning in power transmission system considering FACTS devices and implementing hybrid optimisation approach

This study introduces a techno-economic planning strategy of reactive power (VAr) in power transmission systems. This planning strategy primarily has been focused on reactive power planning (RPP) through operating cost minimisation ensuring cost-oriented system security. The objective function (operating cost) is blended with four different components viz. cost due to real power loss, VAr generation cost, additional VAr compensation devices cost and line charging cost. FACTS (flexible AC transmission system) devices are installed at weak positions through different echelons to improve the system voltage stability. The authors also implemented the probabilistic hybridisation of crow search algorithm and JAYA to find out the optimal set of controlling parameters related to VAr. Finally, a sharp and minute analysis of the results has been done to validate the proposed strategy under multi-loading conditions. To understand the efficiency and efficacy the code profiling and simulation has been rendered on IEEE 30 bus and UPSEB 75 bus test system.

P.591 Orexin-A ameliorates lasting effects of postnatal dysfunctioning of muscarinic cholinergic system on sleep-wakefulness

Needle domains are thin, lamellar domains that can appear as fine lines or stripes in a ferroelectric crystal. They affect the poling, switching, and other properties of ferroelectrics. A model is established to study the stress and electric fields caused by needle domains and their interaction. Considering the electrical and mechanical compatibility conditions at the tip of a needle domain, the fields are represented using equivalent edge dislocations and line charges. Accordingly, the dislocation fields derived by Barnett and Lothe for anisotropic piezoelectric media are employed. A modified Peach–Koehler force and calculations of the total energy due to the needle domains are used to study the formation, interaction and stability of needle patterns, taking full account of the strong anisotropy and electromechanical coupling present.The interaction of pairs of needle domains in an infinite piezoelectric with properties of barium titanate is found to be dominated by the electrostatic terms. This makes comb-like arrays of needle domains unstable if perfectly insulating properties are assumed. By considering redistribution of charge, stable equilibrium states for arrays of needle domains are found; these agree well with experimental observations. The model explains the stability of various observed needle patterns and also how unstable patterns evolve.

Numerical study of space charge electric field inside Resistive Plate Chamber

Resistive plate chamber (RPC) is one of the state-of-the-art particle detection technology for the High Energy Physics (HEP) experiments. The basic operating mechanism of an RPC involves ionization of gas due to the passage of charged particles followed by electron transport, avalanche, and subsequent electromagnetic induction on readout strips due to the movement of the electrons and ions. Especially during streamer mode of operation, the electric field applied to the RPC can get significantly modified due to the presence of a large number of electrons and ions. In this study, we have worked on dominant issues related to the estimation of the electric field due to the space charge arising out of the presence of electrons, ions within an RPC. For this purpose, we have considered two approaches: representation of the space charge cloud as (a) a collection of ring charges, and (b) as a collection of line charges. The results from these different methods have been compared with the results available in the literature.

Visuo-Haptic Simulations to Understand the Dependence of Electric Forces on Distance

In this paper, the potential of visuo-haptic simulators to help engineering students to understand the nature of electric forces between different electric charge distributions is addressed. Three visuo-haptic simulators were designed to perceive the attractive–repulsive behavior as well as the dependence on distance of electrical forces for: (a) point charge, (b) line charge, and (c) plane charge. Design elements were incorporated to improve the 3D perception of the simulators. A sample of N = 111 engineering students practiced with the simulators: 87 enrolled in an Electricity and Magnetism course and 24 enrolled in a more advanced Electromagnetic Fields course. Pre-test and Post-test were applied before and after working with the simulators and average learning gains were obtained. t-tests were performed to determine the statistical significance of the results. Significant learning gains were obtained for the comprehension of the force dependence in the case of line charge and plane charge, but not for the point charge, due to the fact that most students started with very high Pre-test scores in this last case. These results suggest that the use of visuo-haptic simulators may help students to better identify the dependence of electric forces on distance. It was also observed that the potential effect of improving the recognition of electric interactions was higher among students with lower previous familiarity with these topics, as compared to more advanced students. Through exit surveys, it was found that the students liked very much the haptic activity and that it sparked their interest in learning new physical concepts.

Modeling and Optimization of Electrostatic Film Actuators Based on the Method of Moments.

Electrostatic film actuators represent a promising new approach to drive a soft robot, but they lack a comprehensive model to link the design parameters and actuation performance, making actuator design and parameter optimization challenging. To solve this problem, we build a mathematical model based on the method of moments by assuming that each electrode consists of a large number of line charges. This model can directly deduce fluctuation in thrust and adhesive forces during actuator movement, as well as the distribution of electric potential and field strength, for analysis and optimization. It consumes shorter computing time and fewer computing resources, but with comparable accuracy, in comparison with previous indirect means. It is validated by results from both previous studies and on-site experiments. Based on this model, we generate numerous values of actuator output force for different structural parameters. By analyzing the tendency, we summarize a parameter optimization workflow and write an open-sourced program as an example to facilitate the parameter selection for actuator design starting from scratch.