Charge Simulation Research Articles

Finite difference method for electric field optimization in high voltage power transformer bushings using engineering simulation and 3D design program

The electric field optimization minimizing the field strength on an electrode surface and providing its uniformity is important in designing high voltage power transformer bushings and other apparatus from the viewpoint of efficient utilization of the electric field space. The high voltage power transformer bushing with cylinder electrode system has been designed and tested in this investigation. It was found that the insulation method of the cylinder electrode was the most important factor to lower streamer initiation voltage. The optimized design uses both internal and external elements for electric stress grading at critical parts of the bushing. Applying optimization theory based on charge simulation method, the author developed a computation program for electric field automatic optimization in 3D dielectric axisymmetric field. The results of the computation realized some excellent electrode profiles with uniform electric field distribution. Moreover, the discrepancy from the electric field uniformity on 3D dimensional profile caused by applying it to an axisymmetric electrode was discussed. Then a new electrode with uniform field distribution was obtained by using the computation program for optimization.

CFD‐DEM simulation of wall sheeting and particles charge in fluidized beds

AbstractThe effect of the electrostatic charge of particles was investigated in fluidized beds with conductive and nonconductive walls. For this purpose, changes in the wall surface charge density and particle contact time near the wall were examined. Computational fluid dynamics/discrete element method (CFD‐DEM) was utilized to simulate the accumulation of particle and wall‐induced electrostatic charges in a quasi‐two‐dimensional fluidized bed. Particles and walls were initially considered neutral and gained charge with time. The simulations showed that aggregated particles are formed due to the presence of the opposite electrostatic charges. Agglomerates are produced by joining the aggregated particles together. Agglomerates have a layered‐like structure and are made of positive and negative particles. Accumulation of these agglomerates and aggregated particles on the wall forms wall sheeting, which has a layered‐like structure. In other words, particles do not accumulate on the wall individually. A significant accumulation of particles near the wall was seen in the presence of electrostatic charges compared with the neutral bed. Also, the contact time of particles on the wall in the conductive case was more prolonged than in the nonconductive case. The results indicate that the CFD‐DEM approach is a helpful technique for predicting particles behaviour in the presence of the electrostatic charge.

A High-Accuracy and Power-Efficient Self-Optimizing Wireless Water Level Monitoring IoT Device for Smart City.

In this paper, a novel self-optimizing water level monitoring methodology is proposed for smart city applications. Considering system maintenance, the efficiency of power consumption and accuracy will be important for Internet of Things (IoT) devices and systems. A multi-step measurement mechanism and power self-charging process are proposed in this study for improving the efficiency of a device for water level monitoring applications. The proposed methodology improved accuracy by 0.16–0.39% by moving the sensor to estimate the distance relative to different locations. Additional power is generated by executing a multi-step measurement while the power self-optimizing process used dynamically adjusts the settings to balance the current of charging and discharging. The battery level can efficiently go over 50% in a stable charging simulation. These methodologies were successfully implemented using an embedded control device, an ultrasonic sensor module, a LORA transmission module, and a stepper motor. According to the experimental results, the proposed multi-step methodology has the benefits of high accuracy and efficient power consumption for water level monitoring applications.

Self-consistent PIC simulations of ultimate space charge compensation with electron lenses

Further progress of fundamental particle physics requires high intensity and high brightness of accelerated proton and ion beams. This goal is essential for the FAIR hadron beams at GSI, for the neutrino production at the facilities such as Fermilab and JPARC, and for the Large Hadron Collider luminosity at CERN. One of the most formidable obstacles toward that goal is the beam's own space charge, whose forces cause beam emittance growth, losses and lifetime degradation. Typically, such effects become intolerable when the space charge tune-shift parameter Δ QSC exceeds ∼ - (0.25–0.5). To reduce these detrimental effects, it was suggested to use electron lenses to compensate the space charge forces. This paper reports on detailed particle-in-cell space charge and electron lens compensation simulations for extremely intense proton bunches whose space charge tune-shift parameter exceeds -1.0. Different scenarios were evaluated based on reduction in the emittance growth and particle loss at a 4σ aperture. We investigate phenomena and issues related to the focusing lattice errors, importance of the transverse and longitudinal matching of the electron beam profiles to the proton ones, and vary the strength and the number of the electron lenses distributed around a circular machine to optimize the reduction of harmful space charge effects.

Simulation of Radiation Charging of Microelectronic Equipment Cases for Space Applications

A model and a method for mathematical modeling of radiation charging of polymer microelectronic equipment housings with increased conductivity are developed, which are based on the application of the approximation function of the experimental dependence of the housing conductivity on the irradiation time obtained using parametric identification methods. The research results are aimed at developing composite polymer materials for microelectronic equipment housings with a conductivity that ensures the absence of electrostatic discharges and significantly increases the active life of spacecraft.

Numerical Simulation of Transient Surface Charging of Polymer Surface under DC Corona Considering Plasma Chemistry

In this paper, the transient process of negative DC corona generated with needle to plane electrode covered by polymer film is investigated by numerical simulation considering air plasma chemistry. The variation in plasma species in corona discharge and the transient process of charge accumulation on the film are examined. Moreover, the electric field and the mean electron energy distribution on the sample surface are discussed. Obtained results indicate that during the corona process, O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> , O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> are the dominant positive ions, O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> and O are the main negative ion and the neutral particle, respectively. The charge accumulation region expands along the radial direction and the charge density increases gradually. In addition, the discharge channel shape is changed from column to cone with time, which is attributed to the electric field modification achieved by the accumulated charges. In 2000 ns, the mean electron energy distribution on the polymer surface varies between 2.1 and 5.8 eV and finally stabilizes to 3.7 eV, thus the electrons can overcome the barrier at gas-solid interface and become injected into the polymer bulk. It is suggested that the polymer surface charging transient is highly associated with the plasma behavior.

Hybrid Cyber Petri net Modelling, Simulation and Analysis of Master-Slave Charging for Wireless Rechargeable Sensor Networks.

Wireless charging provides continuous energy for wireless sensor networks. However, it is difficult to replenish enough energy for all sensor nodes with fixed charging alone, and even more unrealistic to charge a large number of nodes within a short time via mobile charging. In order to overcome the above weaknesses, this paper firstly puts forward a Master-Slave Charging mode for the WRSN (Wireless Rechargeable Sensor Network), where fixed charging is the master mode and mobile charging is the slave mode, respectively. However, Master-Slave Charging is a typical hybrid system involving discrete event decision and continuous energy transfer. Therefore, the Hybrid Cyber Petri net system is proposed to build a visual specification with mathematical expression of Master-Slave Charging. Moreover, wireless charging in the WRSN is modeled and evaluated from the perspective of a hybrid system for the first time. Furthermore, a greedy-genetic algorithm is proposed to obtain the deployment of fixed chargers and the path planning of a mobile charger, by maximizing the actual electric quantity of the master charging problem and minimizing the mobile charger’s travelling path of the slave charging problem. Finally, the simulation results confirm and verify the Hybrid Cyber Petri net model for Master-Slave Charging. It is worth noting that the proposed model in this paper is highly adaptable to various charging modes in the WRSN.

Assessment of electrical interference on metallic pipeline from HV overhead power line in complex situation

Sharing corridors between high voltage alternating current (HVAC) power lines and metallic pipelines has become quite common. Voltages can be induced on pipelines from HV power lines, which may cause a risk of electric shock to the operator and serious corrosion damage on metallic pipelines. This paper aims to examine the capacitive coupling between aerial metallic pipelines and HV power lines in perfect parallelism case and in general situation which is formed by parallelism, approaches and crossings, using a combination of charge simulation method and Artificial Bee Colony (ABC) algorithm. The electric field at the pipeline's surface and the induced voltage on the pipeline are strongly affected by the pipeline separation distance. The presented simulation results are compared with those obtained from the admittance matrix analysis, a good agreement has been obtained.

Electric and Magnetic Field Estimation Under Overhead Transmission Lines Using Artificial Neural Networks

In this paper, a novel method for electric field intensity and magnetic flux density estimation in the vicinity of the high voltage overhead transmission lines is proposed. The proposed method is based on two fully connected feed-forward neural networks to independently estimate electric field intensity and magnetic flux density. The artificial neural networks are trained using the scaled conjugate gradient algorithm. Training datasets corresponds to different overhead transmission line configurations that are generated using an algorithm that is especially developed for this purpose. The target values for the electric field intensity and magnetic flux density datasets are calculated using the charge simulation method and Biot-Savart law based method, respectively. This data is generated for fixed applied voltage and current intensity values. In instances when the applied voltage and current intensity values differ from those used in the artificial neural network training, the electric field intensity and magnetic flux density results are appropriately scaled. In order to verify the validity of the proposed method, a comparative analysis of the proposed method with the charge simulation method for electric field intensity calculation and Biot-Savart law-based method for magnetic flux density calculation is presented. Furthermore, the results of the proposed method are compared to measurement results obtained in the vicinity of two 400 kV transmission lines. The performance analysis results showed that proposed method can produce accurate electric field intensity and magnetic flux density estimation results for different overhead transmission line configurations.

Analytical Determination of the Slot and the End-Winding Portion of the Winding-to-Rotor Capacitance for the Prediction of Shaft Voltage in Electrical Machines

Common-mode voltage, caused by a 2-level inverter, is a source of discharge currents in motor bearings. Due to the capacitive coupling, between the stator winding and the rotor, an image of the common-mode voltage is produced on the shaft—which can exceed the dielectric strength of the lubrication film of motor bearings. Accurate determination of the winding-to-rotor capacitance is necessary to predict the shaft voltage. This article proposes a novel analytical determination of the slot and the end-winding portion of the winding-to-rotor capacitance. The calculation rules, which are based on the method of image charges and the charge simulation method, take into account the continuity and the boundary conditions of the field areas. Results are validated by means of finite element method simulations. Notably, deviations are in the single-digit percentage range. Furthermore, the presented methods are simple to implement.

Multiscale simulations of charge and size separation of nanoparticles with a solid-state nanoporous membrane.

Nanoporous membranes provide an attractive approach for rapid filtering of nanoparticles at high-throughput volume, a goal useful to many fields of science and technology. Creating a device to readily separate different particles would require an extensive knowledge of particle-nanopore interactions and particle translocation dynamics. To this end, we use a multiscale model for the separation of nanoparticles by combining microscopic Brownian dynamics simulations to simulate the motion of spherical nanoparticles of various sizes and charges in a system with nanopores in an electrically biased membrane with a macroscopic filtration model accounting for bulk diffusion of nanoparticles and membrane surface pore density. We find that, in general, the separation of differently sized particles is easier to accomplish than of differently charged particles. The separation by charge can be better performed in systems with low pore density and/or smaller filtration chambers when electric nanopore-particle interactions are significant. The results from these simple cases can be used to gain insight in the more complex dynamics of separating, for example, globular proteins.

Experimental investigation on dielectric losses and electric field distribution inside nanocomposites insulation of three-core belted power cables

With the advance of nanotechnology in the insulation materials applications the polymers underwent structural changes, seen as individual and multiple nanoparticles techniques, moreover, frequency response analysis (FRA) provides an important prospective design for multiple nanocomposites applications. In this paper, the experimental work has been done for fabrication new polyvinyl chloride nanocomposites that is using individual and multiple nanoparticles to get low dielectric loss under thermal conditions. SEM images have detected the penetration of nano additives inside polyvinyl chloride materials that are obvious the patterns of utilizing individual and multiple nanoparticles. The series of experiments have performed on multi-nanocomposites of polyvinyl chloride samples in reference to additive free multiple nanoparticles (ZnO, Clay, Al 2 O 3 , and Fumed Silica) for controlling on dielectric losses with variant thermal conditions. Also, this paper has been discussed the electric field distribution inside dielectric nanocomposites and multiple nanocomposites for three-core belted power cables based on charge simulation method (CSM). Finally, it has been defined the features layout of using multi-nanoparticles that are enhancing multi-disciplinary properties of polyvinyl chloride as power cables insulation. • Reduction the dielectric losses inside insulation of three-core belted power cables by using nanoparticles. • Optimal electric field distribution inside insulation of three-core belted power cables by using nanoparticles. • Fabrication new polyvinyl chloride nanocomposites with low dielectric loss under thermal conditions. • Layout features of using multi-nanoparticles for enhancing multi-disciplinary properties of polyvinyl chloride.

Bone Morphogenetic Protein 2 (BMP-2) Aggregates Can be Solubilized by Albumin-Investigation of BMP-2 Aggregation by Light Scattering and Electrophoresis.

Bone morphogenetic protein 2 (BMP-2) has a high tendency to aggregate at physiological pH and physiological ionic strength, which can complicate the development of growth factor delivery systems. The aggregation behavior in differently concentrated BMP-2 solutions was investigated using dynamic and static light scattering. It was found that at higher concentrations larger aggregates are formed, whose size decreases again with increasing dilution. A solubilizing effect and therefore less aggregation was observed upon the addition of albumin. Imaged capillary isoelectric focusing and the simulation of the surface charges of BMP-2 were used to find a possible explanation for the unusually low solubility of BMP-2 at physiological pH. In addition to hydrophobic interactions, attractive electrostatic interactions might be decisive in the aggregation of BMP-2 due to the particular distribution of surface charges. These results help to better understand the solubility behavior of BMP-2 and thus support future pharmaceutical research and the development of new strategies for the augmentation of bone healing.

Numerical Method for Calculations of the Multi-Dielectric Fields Based on Flux Density in High Voltage Power Transformer Apparatus

This paper deals with a “combination method” in which the charge simulation method is combined with finite element method, for electric field calculation. The proposed method has the advantages of both charge simulation method and finite element method, while making up of their disadvantages. In the combination method, field is divided into two regions, one covered by the charge simulation method and the other by the finite element method. These two regions are combined using the continuous conditions for potentials and dielectric flux densities at the boundary. The new method could be applied to non-enclosed multi-dielectrics fields, space charge fields, fields with leakage current and so on. Examples of calculation have revealed that the method affords satisfactory calculation accuracy in application to high voltage power transformer apparatuses.

A New Computer Simulation of Avalanche Evolution and Its Transition Into Anode- and Cathode-Directed Streamers in Short Uniform Field Gaps

A new method based on the charge simulation technique is proposed for computing the electric field in a short uniform field gap with space charge and without space charge of avalanches growing in the gap. The self-space-charge field of the avalanche is evaluated to result in field enhancement ahead of the avalanche due to electrons at its head and behind the avalanche due to positive ions in its wake. Also, a criterion is proposed for calculating the breakdown voltage and time-to-breakdown when the primary avalanche crosses the gap. The criterion is based on self-recurrence of the avalanche by secondary processes, and the most dominant one is the photoemission at the cathode. The condition of transition of the primary avalanche to anode- and cathode-directed streamers is formulated where the avalanche is chocked by its self-space-charge field. The number of electrons starting avalanche chains forming the streamers is evaluated in the gas ahead and behind the primary avalanche by photoionization and at the cathode by photoemitted electrons. The present computed values of the breakdown voltage of air at different pressures and N2 at atmospheric pressure as well as the time-to-breakdown in air at atmospheric pressure agree satisfactory with those recorded experimentally. The computed temporal variation of the size of the primary avalanche as influenced by its self-space-charge field agrees with that reported in the literature at different $E/N$ values. The computed current waveforms of the primary avalanche and its successor chains agree reasonably with those measured and those calculated using a finite-element method.

Calculation of Electrostatically Induced Electric Fields in Human Models using a Two-step Process Method of Voxel-based Fast Multipole Surface Charge Simulation Method

Calculation of Electrostatically Induced Electric Fields in Human Models using a Two-step Process Method of Voxel-based Fast Multipole Surface Charge Simulation Method

3D Modelling and simulation analysis of electric field under HV overhead line using improved optimisation method

This study proposes a three-dimensional (3D) quasi-static modelling of the electric field produced by high voltage (HV) overhead power lines using charge simulation method combined with intelligent optimisation algorithms, such as particle swarm optimisation, genetic algorithm and grey Wolf optimiser (GWO), to find the optimal values of parameters for an accurate calculation. Results show that the GWO works better than other algorithms. Several parameters affecting the electric field have been studied; it is observed that taking into account the effect of the exact catenary curve of the power line conductors is much more interesting particularly at the mid-span level where the electric field becomes very significant. According to these values, the limits set by the International Commission on Non-Ionising Radiation Protection guidelines for electric field strength are met for occupational and public exposure. The simulation results are compared with those obtained by the 3D Integration method, a fairly good agreement is found. To confirm the performance and effectiveness of the proposed method, the results obtained are also verified with measurement values available in the literature, a good similarity is achieved.

Phase-field simulation of two-dimensional topological charges in nematic liquid crystals

The concept of topological quantum number, or topological charge, has been used extensively to describe topological defects or solitons. Nematic liquid crystals contain both integer and half-integer topological defects, making them useful models for testing the rules that govern topological defects. Here, we investigated topological defects in nematic liquid crystals using the phase-field method. If there are no defects along a loop path, the total charge number is described by an encircled loop integral. We found that the total charge number is conserved, and the conservation of defects number is determined by a boundary during the generation and annihilation of positive–negative topological defects when the loop integral is confined. These rules can be extended to other two-dimensional systems with topological defects.

Environmental impacts of extreme fast charging

As electric vehicles and their associated charging infrastructure continue to evolve, there is potential to simultaneous alleviate range and recharge concerns with the development of extreme fast chargers (XFC) that can fully charge batteries in PEVs in the span of a few minutes. Recent announcements from EVSE providers and vehicle manufacturers suggest that XFC charging stations, which can recharge a BEV at roughly 20 to 25 miles per minute of charging, and XFC-capable BEVs, could be commercially available within the next 5 years. Our study investigates the potential emission impacts of widespread use of extreme fast charging (350 kW) for electric vehicles in 2030. We conduct a novel vehicle charging simulation model by combining empirical charging behavior data across several data sources. These charging demands are then added as exogenous load to the Grid Optimized Operation Dispatch (GOOD) model, which simulates the operation of generators across the Untied States. We find that XFC can increase both greenhouse gas emissions and local air pollutants, though the results are sensitive to local contexts and grid composition.

Validation of the imaging neutral particle analyzer in nearly MHD quiescent plasmas using injected beam ions on DIII-D

The imaging neutral particle analyzer (INPA) is a scintillator-based diagnostic that provides energy and radially resolved measurements of confined fast ions. To verify operation, understanding and modeling of the diagnostic performance, distributions of deuterium beam ions in low density, nearly MHD-quiescent plasmas are measured on the DIII-D tokamak using the INPA. The distribution is altered by changing the pitch-angle scattering rate with electron cyclotron heating (ECH). Experimental images are mostly reproduced with simulation of core fast ions charge exchanging with injected beam and edge cold neutrals in classical cases. Image comparisons between the experiment and simulation show agreement with less than 25% discrepancies near the beam injection energy of 50 keV. Other strong passive signals, observed in a localized region on the image, are suggested to come from charge exchange between cold neutrals and fast ions around the plasma boundary.