Impulse Voltage Research Articles

Information Measuring System for Correction of Working Memory Parameters in the Learning Processes

This paper presents the results of a system analysis of the information-measuring system (IMS) for correction of the working memory parameters of subjects during the learning process, in which the neuroplasticity of the brain is triggered by stimulating the nerve formations of the neck of a spatially distributed field of voltage impulses, the target of stimulation is the cervical ganglia of the sympathetic nervous system, control of functional changes in the body is carried out according to changes in the parameters of the blood supply system, and psychometric tests are used to assess working memory parameters. Aim. Development of IMS, using neuroelectro¬stimulation of peripheral nerve formations of the neck for correction of working memory parameters in the learning process. Materials and methods. The study involved 65 subjects, divided by randomization into experimental, control and placebo groups. Working memory parameters were assessed using the dual 2-back test, and the functional state was assessed using heart rate variabi¬lity (HRV) analysis. Results. The results of the study showed that the proposed structure of the IMS and the method of correction working memory allow to improve the working memory parameters and normalize state of the autonomic nervous system after three correction procedures. The obtained test results practically do not change and are saved after 2 months. Conclusion. IMS, which provides multichannel neuroelectrostimulation of peripheral nerve formations in the neck, is effective for correction of cognitive skills, which is important for solving problems in the field of education.

Kinetic study about the effect of electric field and contact time of high voltage impulse on reduction of Ca<sup>2+</sup> concentration

Kinetic study about the effect of electric field and contact time of high voltage impulse on reduction of Ca<sup>2+</sup> concentration

Experimental Study on a Compressed Arc Extinguishing Device for Power Distribution Network

A compressed arc extinguishing device for power distribution network is developed to solve the problem of existing anti‐lightning of power distribution network transmission lines. This paper first introduces the arc extinguishing principle of the arc extinguishing device, and then designs the lightning impulse voltage test around the 10 kV transmission line. The test results show that the U50% Lightning impulse voltage of the arc extinguishing device is 112.4 kV considering the atmospheric correction factor. In order to verify the feasibility of the arc extinguishing device, the power frequency continuous current interruption test is designed. The test shows that the arc extinguishing device can extinguish the arc with a peak value of 1.131 kA in 2 ms and does not reignite in the following time. Finally, the device is applied to a 10 kV power distribution network transmission line of China Southern Power Grid. The lightning trip‐out rate of the transmission line per 100 km is reduced from 12.5 (times/year) to 1.1 (times/year), which fully verifies the feasibility of the arc extinguishing device. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Flashover discharges dynamic with continuous and discontinuous pollution layer under lightning impulse stress

The paper is aimed at the study of the dynamic of discharges propagating at the surface of flat PVC insulator (i) with uniform continuous pollution layer and (ii) with uniform discontinuous pollution layer of different conductivities, under lightning impulse voltage for both polarities. It is shown that the morphology of discharges, the current and the voltage as well as the discharge velocity depend on the polarity of voltage, the configuration and the conductivity of the pollution layer; and the behavior of discharges is similar to that of discharges in long air gaps.

Effect Mechanism of Surface Roughness of Solid Dielectrics to Surface Discharge Voltage in Liquid Nitrogen Under Lightning Impulse

The surface discharge of solid dielectric in liquid nitrogen has become one of the key problems in the development of high-temperature superconducting power devices. It is necessary to study the mechanism of surface discharge of the solid dielectric in liquid nitrogen. This article chose polytetrafluoroethylene and DW-3 epoxy resin as specimens, tested the surface discharge voltages of two kinds of specimens with different surface roughness under lightening impulse voltages in liquid nitrogen, and discussed the effect mechanism. The experimental results showed that the surface discharge voltage and discharge time of both materials in liquid nitrogen increased as the surface roughness increasing under lightning impulses. The surface roughness affects the surface discharge voltage of the solid dielectric in liquid nitrogen under lightning impulse, mainly in the charge left on the grinding surfaces of solid dielectrics, the heights of projections, and the creepage distance on the dielectric surfaces. The main discharge process is in the gasification path, and the effect of solid dielectric on surface discharge in liquid nitrogen is smaller. These reasons make the surface discharge in the liquid nitrogen less affected by the surface roughness. The results further explore the characteristics of surface discharge in liquid nitrogen and could provide methodological guidance to improve the surface discharge voltages in liquid nitrogen.

Research on the Time-Domain Dielectric Response of Multiple Impulse Voltage Aging Oil-Film Dielectrics

Power capacitors suffer multiple impulse voltages during their lifetime. With the multiple impulse voltage aging, the internal insulation, oil-film dielectric may deteriorate and even fail in the early stage, which is called accumulative effect. Hence, the time-domain dielectric response of oil-film dielectric with multiple impulse voltage aging is studied in this paper. At first, the procedure of the preparation of the tested samples were introduced. Secondly, an aging platform, impulse voltage generator was built to test the accumulative effect of capacitor under multiple impulse voltage. Then, a device was used to test the time-domain dielectric response (polarization depolarization current, PDC) of oil-film dielectric in different aging states. And finally, according to the PDC data, extended Debye model and characteristic parameters were obtained by matrix pencil algorithm identification. The results indicated that with the increase of impulse voltage times, the time-domain dielectric response of oil-film dielectric changed accordingly. The polarization current curve moved up gradually, the insulation resistance decreased when subjected to the repeated impulses. In frequency domain, the frequency spectrum of tan δ changed along with the impulse accumulation aging, especially at low frequency. At last, combined with the aging mechanism of oil-film dielectric under multiple impulse voltage, the test results were discussed.

Interaction Between Partial Discharge and Generated Bubbles Under Repeated Lightning Impulses in Transformers Using a Complex Structure Model

The focus of this research is on the insulation structure where radial and axial spacers connect in a power transformer. The interaction between the occurrence of partial discharge (PD) and the generation of bubbles using a model that is very similar to the real structure in a transformer is studied. The inception voltage of the PD caused by the oil gap created by the axial and radial spacers might lower than that caused by a metallic impurity. However, PD caused by the metallic impurity was more likely to generate bubbles because of its higher discharge energy. It is also found that the residual space charge on the insulation surface prevents the occurrence of PD and also affects the generation of bubbles under repeated lightning impulse voltage. Moreover, it is found that generated bubbles do not affect the occurrence of PD. One reason for this is that the bubbles disappear during the interval time between repeated impulses. The effect of the residual space charge is considered to be another reason.

Measurement of Streamer Propagation Velocity over Solid Insulator Surface in a C4F7N/CO2/O2 Mixture under Lightning Impulse Voltages

For a better understanding of the discharge development over a solid insulator surface, experiments are conducted over epoxy-anhydride resin samples in a C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> N/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 </sub> mixture under lightning impulse voltages. A measurement method of streamer propagation velocity using a photomultiplier is presented. It is observed that the propagation velocity greatly depends on the gas nature, the polarity of the voltage, and the high voltage electrode geometry. The involved mechanisms in propagation are also discussed.

Experimental Study on the Effect of Lightning Impulse Oscillation Frequency on Pressboard Flashover in Oil

In this work, effect of the oscillation frequency on the oil surface flashover characteristics under lightning impulse voltage is experimentally studied. Four lightning impulse (OLI) waves with different oscillation frequencies and 1.2/50 μs standard lightning impulse (SLI) wave are used in this study. The experiment results show that flashover voltages under OLI are larger than those under SLI and the flashover time lags under OLI are longer than those under SLI. Additionally, the flashover voltage tends to increase and the time lag tends to be shorter as the oscillation frequency increases. According to the experimental results and the discharge theory of liquids, we believe that the waveform oscillation frequency affects both the effective electron generation time lag and the formative time lag. This work provides a reference for the waveform selection of the on-site withstand voltage test and explains the physical mechanism of the oil flashover discharge from the perspective of impulse waveform oscillation.

Characteristics of Creepage Discharge in Oil/Pressboard Composite Insulation

This paper deals with partial discharge characteristics in oil/pressboard composite insulation system, which is used in oil-immersed power transformer. It is found that the discharge propagates in the same route on the pressboard surface as in the previous discharge every time under repeated impulse voltage application. We also revealed that the white trace remained along the path of discharge and affected the subsequent discharge progress because of being a weak point part on insulation. This study presents an investigation of the effect of the white trace on partial discharge inception voltage (PDIV) of the composite insulation system with high-speed optical observation and electrical measurements for the discharge propagation. The discharge propagation mechanism is also discussed with comparing the discharge progress characteristics before and after the white trace formation.

Electric Field Simulation of Permittivity and Conductivity Graded Materials (ε/σ-FGM) for HVDC GIS Spacers

This paper discusses the application of the novel technology - functionally graded material (FGM), which combines both spatial permittivity (ε) and conductivity (σ) distributions with the aim to control the electric field around DC-GIS spacer. Some distribution types of ε and/or σ in the spacer bulk, such as U-type and graded to higher conductivity (GHC) are investigated through electric field simulation, in comparison to the uniform spacer with constant ε and σ distributions. The electric field relaxation effect of each distribution type of ε/σ-FGM under DC steady state, DC polarity reversal, DC-on, and lightning impulse voltage superimposed on DC steady state condition are obtained. The results show that ε/σ-FGM with U-type permittivity and GHC-type conductivity distribution of which low σ is applied near the high voltage side of the DC-GIS spacer is the most effective in reducing the maximum electric field under all stated conditions.

Recognition of complex and multiple power quality disturbances using wavelet packet-based fast kurtogram and ruled decision tree algorithm

This paper introduces an algorithm based on wavelet packet supported fast kurtogram and decision rules for the identification and classification of complex power quality (PQ) disturbances. Features are extracted from the signals using fast kurtogram, envelope of filtered voltage signal and amplitude spectrum of squared envelop. Proposed algorithm can be implemented for the recognition of the complex PQ disturbances, which include the combination of voltage sag and harmonics, voltage momentary interruption (MI) and oscillatory transient (OT), voltage MI and harmonics, voltage sag and impulsive transient (IT), voltage sag, OT, IT and harmonics. Proposed work has been performed using the MATLAB software. Performance of the algorithm is compared with performance of algorithm supported by discrete wavelet transform (DWT) and fuzzy C-means clustering (FCM).

Virtual instrument for estimation of HVAC and HVDC test parameters according to IEC 60060-1:2010

High and ultra high voltage tests are commonly carried out to determine external and internal dielectric performances of electric power equipment. The standardization of these tests in different laboratories is obtained by following the standards with the requirements necessary to perform the tests. Among such requirements, the test voltage parameters must be measured within acceptable uncertainties. For a correct analysis of the test and presentation of the results it is necessary that the measuring system and the instrument used be able to estimate all parameters according to standard IEC 60060-1:2010, depending on each type of voltage and test, AC, DC or impulse. However, simpler conventional instruments, such as multimeters, are not capable of measuring and indicating all parameters required by current standards. Thus, dedicated instruments and software are needed, capable of performing the analysis of these parameters within the acceptable uncertainty limits. The use of software or measurement algorithms for voltage impulse testing is already described in IEC 61083-1 and -2 standards. Specifically, part 2 presents the reference waveforms used for the validation of the software used in the tests. Similarly, IEC 61083-4 is being developed for high voltage AC and DC tests, with standard waveforms for validation of the measurement software. The objective of this work is presenting the HVAT AC-DC virtual instrument developed in LabVIEW environment, capable of estimating the required AC and DC test parameters of the ABNT NBR IEC 60060-1:2013 standard and analyzing the robustness of such a virtual instrument through low and high voltage tests.

Kinetic Study of CaCO3 Precipitation Accelerated by High Voltage Impulse

Objectives : Determination of reaction order (n) and rate constants (k) of the CaCO&lt;sub&gt;3&lt;/sub&gt; scale formation reaction that was accelerated by the HVI (high voltage impulse) induction.Methods : HVI was inducted to the synthetic solution containing 2.5 mM of Ca&lt;sup&gt;2+&lt;/sup&gt; ion at different temperatures of 25, 40, 60℃. The concentration of Ca&lt;sup&gt;2+&lt;/sup&gt; ion has been monitored as voltages of the HVI increased from 0 to 5, 10, 15 kV. Reaction order and the rate constants of the CaCO&lt;sub&gt;3&lt;/sub&gt; formation reaction were determined with the experimental dataset of Ca&lt;sup&gt;2+&lt;/sup&gt; concentration vs. time plots.Results and Discussion : The CaCO&lt;sub&gt;3&lt;/sub&gt; formation was determined to follow two-molecules 2&lt;sup&gt;nd&lt;/sup&gt; order reaction. The reaction rate constant, k increased as temperature and the applied voltages of HVI increased. The rate constant, k at 25℃ and 15 kV of HVI was 8.2×10&lt;sup&gt;-3&lt;/sup&gt; L/(mmol･hr), which was 2.7 times greater than the k of the control at 25℃, 3.0×10&lt;sup&gt;-3&lt;/sup&gt; L/(mmol･hr).Conclusions : The reaction of CaCO&lt;sub&gt;3&lt;/sub&gt; formation was accelerated by HVI as the applied voltages of HVI increased, indicating that the HVI could be used as an alternative desalting technology for scale control.

Model test on the effect of hillside on lightning shielding performance of ±1100 kV transmission lines

Lightning damage is one of the main causes of faults in transmission lines. To study the effect of terrain on the lightning shielding performance of UHV transmission lines, with negative 250/2500 μs switching impulse voltage, a large-sized model of the Z38102AL tower with the ratio of 1:12.5 for ±1100 kV UHV transmission lines is used to conduct the simulation tests in hillside in this paper. According to the pictures of discharge process, the discharge process of transmission line around the hillside area is analyzed. The results show that the ground potential rise in the hillside area changes the space electric field, and the attraction of the slope to the downward leader makes the transmission lines in the hillside area more vulnerable to lightning. The test results show that the equal probability curve of the shielding failure spatial region is inclined parabola curve, and the shielding effect of the slope is weak, the dispersion of discharge increases, which leads to the decrease of the difference in the attraction ability of the conductor voltage polarity to lightning. By comparing the test results with the plain model test, the results show that distribution of discharge is larger and the total shielding failure probability is higher in hillside area. Conclusively, under the influence of hillside slopes, the increase of exposure space and the change of space electric field caused by the rise of ground potential have a stronger effect on the shielding failure probability than the polarity effect of conductor voltage, which makes the difference of conductor polarity in hillside area smaller. It is found that the influence of voltage polarity of ±1100 kV conductor on the probability of shielding failure is stronger by comparing the results of ±1100 kV test and ±800 kV test.

Design and concept proof of an inductive impulse self-destructor in sense-and-react countermeasure against physical attacks

This paper presents an inductive impulse self-destruction circuit utilized in a sense-and-react IC-level countermeasure against physical attacks on a cryptographic processor. Triggered upon an alarm signal assertion by an integrated attack sensor, the proposed circuit instantaneously generates >10 V high-voltage impulse to permanently destruct the cryptographic processor for enhancing tamper resiliency. A compact design with only a single on-chip inductor and a transistor significantly saves the hardware overhead. The inductor accumulates large electric energy in its magnetic field and the switch transistor suddenly opens the accumulated energy to boost the impulse voltage in an inertial manner. Since the inductor is drawn over the cryptographic core by existing on-chip IC interconnections, no extra area for the inductor and no any optional IC process steps are needed. This fully standard CMOS compatible, complete circuit solution, results in no fabrication cost penalty. A prototype implemented in both discrete components and a 0.18 μm standard CMOS process successfully demonstrated the-proof-of-concept.

Drift-diffusion model of corona discharge in coaxial geometry due to negative lightning impulse voltage

Corona discharge at atmospheric pressure in cylindrical geometry is simulated numerically for negative lightning voltage impulse. The simulation is performed by solving the drift-diffusion-reaction equations for electrons, positive and negative ions. Spatial dependence and time evolution of the concentration of charged particles and created space electric field are used for detailed theoretical analysis of corona discharge based on the values of the transport and reaction gaseous coefficients. This exact drift-diffusion model enables clear physical picture of the corona discharge dynamics. It is used for the determination of the charge-voltage curves necessary for taking into account the corona effects in transient overvoltage calculation on transmission lines. In contrary to the previous engineering corona models, it is shown that the corona charge continues to increase although the input voltage pulse decreases after reaching its maximum value. This behavior is confirmed by measurements in a few experimental studies. Secondly, it has been shown that according to this model there are no positive streamers formation departing from central electrode or wire during decreasing edge of the input voltage pulse. The total charge simply commences to decrease when the negative ions neutralize themselves on the central electrode or wire of positive polarity. A sharp peak of corona current is observed immediately after the beginning of the intense ionization. The drift-diffusion model could also be used to check the validity of other common assumptions and predictions of previous engineering corona models.

Design and Experimental Study of Traveling Wave Signal Generator for Distribution Network

Aiming at the problem of operation safety and stability of electrical equipment in distribution network caused by impulse voltage, this paper will study and analyze the traveling wave signal generator. Through the study of the standard lightning wave shape characteristics and the mechanism and characteristics of the existing lightning impulse voltage signal generator equipment, the working principle of the corresponding traveling wave signal generator was designed and the relevant parameters were calculated. Finally, the results of the research and analysis were simulated and analyzed with the Multisim simulation software. Test results show that the impulse voltage generated by the full wave form basic satisfy the provisions of this design is expected waveform, and consistent with the actual lightning wave shape, therefore, this thesis studies the traveling wave signal generator unit can meet the normal travelling wave signal of traveling wave positioning system requirements, verify the real effectiveness and practicability of this thesis research.

Impulse Breakdown Characteristics of Transformer Oil with Cellulose Particles in Quasi-Uniform Field

This study presents an experimental comparison of the breakdown characteristics of oil samples with four cellulose particle content levels in a quasi-uniform electric field under lightning impulse voltage. For the experiment to resemble the actual working conditions of transformers and meet the on-site withstand impulse voltage test requirements, both the standard lightning voltage (SLI) and oscillating lightning impulse (OLI) are considered. The experimental results show that an increase in the number of cellulose particles directly weakens the oil insulation strength. At the same particle content level, the oil breakdown voltage under OLI is higher than that under SLI, and the breakdown time lag under OLI is longer than that under SLI. The breakdown time lag is more sensitive to the effect of particle content under SLI. This work is beneficial in deepening the understanding of the impulse breakdown characteristics of transformer oil within cellulose particles and in providing references for the on-site impulse test of oil-immersed power transformers.

Design of 4-stage Marx generator using gas discharge tube

In this paper, a Marx generator voltage multiplier as an impulse generator made of multi-stage resistors and capacitors to generate a high voltage is proposed. In order to generate a high voltage pulse, a number of capacitors are connected in parallel to charge up during on time and then in series to generate higher voltage during off period. In this research, a 6kV Marx generator voltage multiplier is designed using gas discharge tube (GDT) as an electronic switch to breakdown voltage. The Marx generator circuit is designed to charge the storage capacitor for high impulse voltage and current generator applications. According to IEC 61000-4-5 class 4 standards, the storage capacitor must be charged up to 4 kV. The results show that the proposed Marx generator can produce voltages up to 6.8 kV. However, the storage capacitor could be charged up to 1 kV, instead of 4 kV in the standard. That is because the output impulse voltage has narrow time period.