Selected Papers from 2020 IEEE International Conference on High Voltage Engineering (ICHVE 2020)

The 2020 IEEE International Conference on High Voltage Engineering (ICHVE 2020) was held on 6–10 September 2020 in Beijing, China. The conference was organized by the Tsinghua University, China, and endorsed by the IEEE Dielectrics and Electrical Insulation Society. This conference has attracted a great deal of attention from researchers around the world in the field of high voltage engineering. The forum offered the opportunity to present the latest developments and different emerging challenges in high voltage engineering, including the topics of ultra-high voltage, smart grids, and insulating materials

Power system applications of fiber optics

Power system applications of optical systems, primarily using fiber optics, are reviewed. The first section reviews fibers as components of communication systems. The second section deals with fiber sensors for power systems, reviewing the many ways light sources and fibers can be combined to make measurements. Methods of measuring electric field gradient are discussed. Optical data processing is the subject of the third section, which begins by reviewing some widely different examples and concludes by outlining some potential applications in power systems: fault location in transformers, optical switching for light fired thyristors and fault detection based on the inherent symmetry of most power apparatus. The fourth and final section is concerned with using optical fibers to transmit power to electric equipment in a high voltage situation, potentially replacing expensive high voltage low power transformers. JPL has designed small photodiodes specifically for this purpose, and fabricated and tested several samples. This work is described

High Voltage Insulating Materials-Current State and Prospects

Studies on new solutions in the field of high-voltage insulating materials are presented in this book. Most of these works concern liquid insulation, especially biodegradable ester fluids; however, in a few cases, gaseous and solid insulation are also considered. Both fundamental research as well as research related to industrial applications are described. In addition, experimental techniques aimed at possibly finding new ways of analysing the experimental data are proposed to test dielectrics

Power system real-time thermal rating estimation

This Thesis describes the development and testing of a real-time rating estimation algorithm developed at Durham University within the framework of the partially Government-funded research and development project “Active network management based on component thermal properties”, involving Durham University, ScottishPower EnergyNetworks, AREVA-T&D, PB Power and Imass. The concept of real time ratings is based on the observation that power system component current carrying capacity is strongly influenced by variable environmental parameters such as air temperature or wind speed. On the contrary, the current operating practice consists of using static component ratings based on conservative assumptions. Therefore, the adoption of real-time ratings would allow latent network capacity to be unlocked with positive outcomes in a number of aspects of distribution network operation. This research is mainly focused on facilitating renewable energy connection to the distribution level, since thermal overloads are the main cause of constraints for connections at the medium and high voltage levels. Additionally its application is expected to facilitate network operation in case of thermal problems created by load growth, delaying and optimizing network reinforcements. The work aims at providing a solution to part of the problems inherent in the development of a real-time rating system, such as reducing measurements points, data uncertainty and communication failure. An extensive validation allowed a quantification of the performance of the algorithm developed, building the necessary confidence for a practical application of the system developed

The effect of space charges on the conductivity of dielectrics under medium direct voltage stress conditions

Conduction and space charge theories in dielectrics under direct voltage conditions are reviewed and analysed. Published information on gas discharge processes in insulation, conductivity, discharge detection and measuring methods are also summarised. A combined technique whereby both discharges and current can be studied simultaneously is employed in the investigation of non-ohmic conduction in solid dielectrics at moderate d.c. stresses. Experimental evidence suggests that none of the conventional laws of conduction adequately explains the observed phenomena e.g. the thickness dependence of conductivity; and that the operating stress 'E' calculated as the ratio of the externally applied voltage to the thickness of the dielectric may not be the actual resultant stress. Some anomalies are explained on the basis of a new dielectric equivalent circuit, a modified Maxwellian 'n' strata dielectric and induced interfacial or space charges. The discharge behaviour of gaseous voids in dielectrics is analysed using an equivalent circuit incorporating the resistivity of the void gas. Extinction is explained partly by an extended Maxwellian polarisation phenomena...

Assessment of Power System Equipment Insulation Based on Distorted Excitation Voltage

Electrical insulation plays a critical role in high voltage power system equipment. The presence of electrical, thermal, and mechanical stresses imposed when they are in operation for a long time cause gradual degradation of the insulation. Therefore, regular condition monitoring and diagnostic testing of power system equipment are of paramount importance for the reliable operation of electricity supply networks and systems. The dielectric dissipation factor (DDF) measurement is one of the most common techniques for insulation assessment. From a traditional perspective, a pure sinusoidal voltage is used for excitation in the testing. However, the grid voltage nowadays in reality is often distorted with a waveform having multiple harmonic components. Generally, there are distorted voltages and currents generated due to the presence of non-linear equipment or components in the system. Thus, testing under distorted voltage with harmonics provides a more realistic diagnostic measurement as compared to traditional AC sinusoidal high voltage testing. This dissertation investigates the impact of harmonically distorted excitation on the dielectric dissipation factor of high voltage power equipment. A practical measurement method based on distorted excitation is proposed and tested on a reference capacitor-resistor test object. A theoretical and mathematical model is developed to quantify the impact of distortion on the DDF measured in contrast to the case of non-distorted excitation. It is established that for the same total RMS magnitude of the applied excitation, the DDF decreases with the increasing harmonic proportion in the applied voltage waveform. For validation, laboratory experiments and computer simulations were carried out, and data obtained were compared with the analytical results. The proposed technique is then tested on some real high voltage components (33kV dry-type current transformers). The results confirm the monotonically decreasing trend, but the pattern is more complex. The dielectric dissipation factor mathematical and electrical circuit model is implemented based on the polarisation loss. The theoretical formulation is implemented in a computer simulation using MATLAB Simulink to validate the results. In summary, the thesis provides useful diagnostic insights on the characteristics of the dielectric dissipation factor measurement under distorted excitation

Non-Invasive Picosecond Pulse System for Electrostimulation

Picosecond pulsed electric fields have been shown to have stimulatory effects, such as calcium influx, activation of action potential, and membrane depolarization, on biological cells. Because the pulse duration is so short, it has been hypothesized that the pulses permeate a cell and can directly affect intracellular cell structures by bypassing the shielding of the membrane. This provides an opportunity for studying new biophysics. Furthermore, radiating picosecond pulses can be efficiently done by a compact antenna because the antenna size is comparable to the pulse width. However, all of the previous bioelectric studies regarding picosecond pulses have been conducted in vitro, using electrodes. There is not yet a device which can non-invasively deliver picosecond-pulsed electric fields to neurological tissue for therapeutic applications. It is unclear whether a radiated electric field at a given penetration depth can reach the threshold to cause biological effects. In this dissertation, a picosecond- pulsed electric field system designed for the electrosimulation of neural cells is presented. This begins with the design of an ultra-wideband biconical dielectric rod antenna. It consists of a dielectrically loaded V-conical launcher which feeds a cylindrical waveguide. The waveguide then transitions into a taper, which acts like a lens to focus the energy in the tissue target. To describe the antenna delivery of picosecond pulses to tissues, the initial performance was simulated using a 3-layer tissue model and then a human head model. The final model was shown to effectively deliver pulses of 11.5 V/m to the brain for a 1 V input. The spot size of the stimulation is on the order of 1 cm. The electric field was able to penetrate to a depth of 2 cm, which is equal to the pulse width of a 200 ps pulse. The antenna was constructed and characterized in free space in time domain and in frequency domain. The experimental results have a good agreement with the simulation. The ultimate biological application relies on adequate electric field. To reach a threshold electric field for effective stimulation, the antenna should be driven by a high voltage, picosecond-pulsed power supply, which, in our case, consists of a nanosecond charging transformer, a parallel-plate transmission line, and a picosecond discharging switch. This transformer was used to charge a parallel-plate transmission line, with the antenna as the load. To generate pulses with a rise time of hundreds of picoseconds, an oil switch with a millimeter gap was used. For the charging, a dual resonance pulse transformer was designed and constructed. The novel aspect of this transformer is has a fast charge time. It was shown to be capable of producing over 100 kV voltages in less than 100 ns. After the closing of the peaking switch and the picosecond rise time generation, the antenna was able to create an electric field of 600 V/cm in the air at a distance of 3 cm. This field was comparable to the simulation. Higher voltage operation was met with dielectric breakdown across the insulation layer that separates the high voltage side and the ground side. Before the designed antenna is used in vivo, it is critical to determine the biological effect of picosecond pulses. This is especially important if we focus on stimulatory effects, which require that the electric field intensity be close to the range that the antenna system can deliver. Toward that end, neural stem cells were chosen to study for the proliferation, metabolism, and gene expression. Instead of using the antenna, the electrodes were used to deliver the pulses to the cells. In order to treat enough cells for downstream analyses, the electrodes were mounted on a 3-D printer head, which could be moved freely and could be controlled accurately by programming. The results show that pulses on the order of 20 kV/cm affect the proliferation, metabolism, and gene expression of both neural and mesenchymal stem cells, without reducing viability. In general, we came to the conclusion that picosecond pulses can be a useful stimulus for a variety of applications, but the possibility of using antennas to directly stimulate tissue functions relies on the development of a pulsed power system, high voltage insulation, and antenna material

Dielectrics - Digest of literature, volume 28, 1964

Dielectric constants, dipole moments, relaxation times, conduction phenomena, insulating films, breakdown, materials, and applications of dielectrics - annotated bibliograph

Process techniques study of integrated circuits Final scientific report

Surface impurity and structural defect analysis on thermally grown silicon oxide integrated circui

Fundamental and applied aspects of contact electrification

Apparatus has been developed, which permits the measurement of electrification produced by rolling or sliding contact between a spherical specimen, and a plane dielectric sample. Measurements of the charge transferred to metal contact spheres, and the two-dimensional dielectric surface charge distribution, have been carried out under controlled conditions. The dissipation processes of air breakdown and bulk condution have been studied. The importance of metal work function, dielectric material, the normal force during contact, the mode of contact, and the time of contact has also been investigated. Contact electrification and charge dissipation occurring in a vibrated bed have been studied. The variables of interest were the bulk particle resistivity, the amplitude of vibration, and the. system electrode geometry. Theoretical models have been developed for the processes occurring, and the models could be used to interpret experimental observations. The relevance of the results to previous particle electrification studies, and to general particle handling situations has been discussed. Two new applications of particle charging have been examined. The first utilised particle contact electrification occurring naturally in a fluidised bed. By applying a suitable alternating electric field normal to an immersed heater surface, considerable increases in the heat transfer coefficient have been obtained, as a result of the imposed particle movement. The influence on the heat transfer coefficient, of the electric field magnitude and frequency, together with the fluidising air velocity, has been studied. The second application involved devising a novel means of electrostatic separation, using induction charging applied to the particles on the surface of a vibrated bed. A theoretical model for predicting particle collection rates has been developed, and verified by comparison with experimental observations. An efficient separation has been demonstrated on a combined size/resistivity basis