Analysis for discharge-radiation dynamics in alternating current plasma display panels

The objective of this paper is to present an approach for isolating the harmonic contents in both voltage and current waveforms of the montage feeder of Gharb Talkha substation (60/11 KV). A novel technique using Discrete Wavelet transform (DWT) for the analysis of the waveforms harmonics content At the beginning the substation is simulated using Simulink toolbox in Matlab program with and without the presence of capacitor bunk. The obtained voltage and current waveforms are compared to the actual data. The proposed model is used to study the effect of replacing the capacitor bank with single tuned parallel passive filter. The resulting current and voltage waveforms are analyzed using the proposed DWT technique. The analysis showed that the Total Harmonic Distortion (THD) of both voltage and current waveforms is improved as well as the power factor.

When the soil invaded by water as the grounding medium in green power generation sites near river basins, on the coast, is dominantly characterized in terms of its resistivity, the characteristics of the voltage and current waveforms on transient discharges such as the soil can be experimentally investigated using the liquid gap, reproducing the resistivity of the soil. The transient discharge characteristics is available information on the surge withstand rating of surge protective devices used in the green power generation sites. Experimental results on the behaviour of lightning impulse discharges in a tap-water gap are reported; these results show that the resistivity of tap water is nearly equal to those of a river and cultivated and marshy land. Further, (1) the discharge voltage and current waveforms indicate the periodic attenuated waveforms for one period, and the voltage waveforms indicate amplitude distortions; (2) the discharge impedance obtained using the fitting curves to the discharge waveforms ranges from 1 to 2.5 times that of the tap-water resistance, i.e., 80Ω, and from 8 to 3.2 times that for positive and negative rod discharges.

In the paper the long arc in free air is investigated. First, the arc is initiated under laboratory conditions in the high power test laboratory FGH-Mannheim (Germany). Based on the laboratory obtained data records, the main features of the arc are derived. By this arc voltage and current are processed. An important feature of the arc, the variation of arc length, is analyzed. Based on the analysis of arc voltage and current wave forms, the new dynamic arc model, taking into account the arc length variation, is derived. The arc is modeled as a current dependent voltage source with the characteristic distorted rectangular waveform and arc length dependent amplitude. The arc is considered as a source of higher harmonics distorting by this other signals in the network. An example of arc computer simulation using the new dynamic model is given. The main features of the simulated arc are also presented. Features of both the real and the simulated arc are given in the time and the spectral domains.

Pantograph arcing with AC supply generates transients, cause asymmetries and distortion in supply voltage and current waveforms and can damage the pantograph and the overhead contact line. The asymmetry generates a net dc component and harmonics, which propagate within the traction power and signalling system and causes electromagnetic interference. Unlike DC-fed systems (Part I), the arcing in ac supply is complex because of the zero crossing of currents and voltages. In this paper, we discuss the mechanisms of sliding contact and arcing between pantograph-contact wire using the experimental setup described in Part I. Influences of various parameters and test conditions on arcing phenomenon and their signature patterns on the supply voltage and current waveforms are presented. It is shown how the arcing mechanism and corresponding asymmetry in the voltage and current waveforms are governed by line speed, current, supply voltage, inductive load, and pantograph material. The asymmetry in the current waveform is mainly due to the difference in the duration of successive zero-current regions and uneven distortion of the waveshapes. This, in turn, creates the asymmetry in the voltage waveform. The findings presented in this paper could be beneficial for coming up with appropriate mitigation techniques from the electromagnetic interference due to pantograph arcing in AC traction systems.

Negative oxygen ions (O2− + O−) in the bulk of a dc discharge for Ar/O2 gas mixture have been determined employing Langmuir probe-assisted laser photodetachment. Electron density and temperature were obtained for the mixture at discharge powers between 2 and 15 W and pressure between 75 and 375 mtorr. Electron temperature shows very minimum dependence on pressure, while electron number density is increasing with power and decreasing as a function of pressure. Total negative ion number density showed an increasing trend as a function of power, while decreasing as the pressure was increased at a constant discharge power. Equally negative ion density was found to decrease as the O2 percentage in the mixture was increased under the same conditions of discharge pressure and power. The maximum negative ion number density was found to be about 6.5 E14 at 75 mtorr and 5.5 W of power with 25% O2 in the mixture. The electronegativity at 150 mtorr pressure and 5 W of discharge power was found to decrease from 0.21 to a minimum of 0.06 and increase again to 0.11 as the O2 partial pressure was varied from 25% to 100% with the minimum at 75% O2.

The atmospheric pressure glow discharge has a good industrial application prospect, but it is difficult to obtain a stable and diffusive atmospheric pressure glow discharge, especially in the large ambient air gap. In this paper, with a transverse magnetic field applied in the pin-to-ring electrode gap, a stable and diffusive atmospheric pressure glow discharge in ambient air was obtained. The influence of different factors such as the output-voltage amplitude of the power supply, the intensity of the external magnetic field, and the different sizes of ring-cathode were studied from the discharge voltage and current waveforms and the discharge morphology. The results show that a more diffusive and bigger-volume glow discharge can be obtained by increasing the amplitude of the output voltage or the intensity of the external magnetic field, and the more uniform and effective glow discharge can be obtained when choosing the smaller pin-to-ring inter-electrode gap.

An experimental investigation of a TRAPATT diode with its oscillator circuit is presented. The measurements of current and voltage waveforms were made with a sampling oscilloscope (3 dB bandwidth, 14 GHz)and an improved capacitive voltage-divider probe. Design information is given for this type of probe which can have an almost unlimited bandwidth. Voltage and current waveforms across the semiconductor chip are presented for a diode that oscillated at 1 GHz with an efficiency of 49%. It is shown that the mode of operation and the waveforms are explained well by a simple theoretical model that has been developed.

In this chapter, we shall discuss techniques used to fit faulted current and voltage waveforms, each to a sinusoidal waveform containing a fundamental component, a decaying/constant direct current (DC) component and/or harmonics.These techniques use the least squares (LSQ) method to minimise the fitting error, and all have the common goal of extracting the fundamental components of voltage and current waveforms, to calculate the impedance to the fault or the comparison of current-based signals in digital differential protection.

Voltage source inverter (VSI) had been used in dc traction power substation to deliver the trains braking energy back to the utility grid. To mitigate low order harmonics components, pulse-width-modulation (PWM) technique is commonly used in VSI controlled. As a result, the ac voltage and current waveforms may contain high frequency ripples. This paper proposes to mitigate the high frequency harmonics using LCL-filter with series <em>R</em>-damper. This filter offers good attenuation on harmonics with smaller size compare to other passive filter topologies. Theoretical analysis and simulation verification are conducted in designing the proposed filter. System level simulation had also been carried out. Sinusoidal grid current and voltage waveforms are recorded (THD<2%). This paper also includes damping losses analysis in conjunction with resonance peak suppression in designing the <em>R</em>-damper.

Summary form only given. A novel kind of millimeter cold plasma jet is achieved in atmospheric pressure of He, by capillary quartz dielectric barrier discharge (DBD) powered by a sinuous power source with frequency of 33 kHz. There are two different discharge regions in the generator: the filament discharge in the DBD gap and the plasma jet near the outlet of the capillary. The coexistence of the two discharge regions and the flow of the working gas are two basic requisites for generating the cold plasma jet. The temperature of the plasma jet is verified to be lower than any other continuous atmospheric discharges by two kinds of spectroscopic methods. The emission spectra from helium atoms is used to obtained the excitation temperature of the plasma jet by the Boltzmann plot scheme and the rotational spectral structure of the first negative band of nitrogen is used to simulate the plasma thermal-dynamic temperature. The tendencies of the two jet temperatures on the discharge power and the gas flow rate are investigated in detail. The results show that the plasma thermal-dynamic temperature lies in the range of 300-450 K while rising slightly with the discharge power and dropping with the gas flow rate. The excitation temperature of the jet rises with the discharge power but lies in range of 2000-3000 K, which is much lower than that of arc plasmas and plasma torches. The plasma power input is obtained from the discharge waveforms of voltage and current

The telegraph model describes that the current and voltage waves can be reflected on a wire, that symmetrical wave patterns can form along a line. A numerical study of these voltage and current waves on a transferral line has been proposed via a modified extended cubic B-spline (MECBS) method. The B-spline functions have the flexibility and high order accuracy to approximate the solutions. These functions also preserve the symmetrical property. The MECBS and Crank Nicolson technique are employed to find out the solution of the non-linear time fractional telegraph equation. The time direction is discretized in the Caputo sense while the space dimension is discretized by the modified extended cubic B-spline. The non-linearity in the equation is linearized by Taylor’s series. The proposed algorithm is unconditionally stable and convergent. The numerical examples are displayed to verify the authenticity and implementation of the method.

Voltage dip generator for testing wind turbines connected to electrical networks

In order to obtain the characteristics of magnetic core under … 0:5{5 „s saturation time, a one-stage magnetic pulse compression circuit without external demagnetization circuits which are commonly used in magnetic compressors is designed. The current through the core is calculated by voltage across the resistive load, and the loop voltage is picked up with a single wire loop and integrated by software. B{H curves are derived from the measured voltage and current wave forms. B{H curves show that the core loss is in inverse proportion to the time to saturation, whereas the percentile core loss decreases as the charging energy increases. While the eddy current loss and dissipated energy are in direct proportion to dB/dt. The low inductance of magnetic switch indicates that the core is saturated and behaves as an air core. By applying custom characteristics to each stage in Pspice simulation, more practical energy transfer in magnetic pulse compression and the efiects of leakage current are presented.

The improvement of luminosity and luminous efficiency is the one of the most important tasks in alternating current plasma display panels. The influence of gas mixture ratio, Ne–Xe and He–Ne(27%)–Xe(3%), on luminosity and luminous efficiency in surface discharge alternating-current plasma display panels has been investigated. It is found that discharge power does not strongly depend on the gas mixtures, while the luminosity for three species mixture gas, He–Ne(27%)–Xe(3%), is shown to be much higher than those for the two species mixture gas of Ne–Xe. The three species mixture gas, He–Ne(27%)–Xe(3%), can be suggested as the one of the candidates for achieving high luminosity and luminous efficiency for color plasma display panels, based on the experimental observations of luminosity, discharge power, response time, and efficiency.

Spectroscopic and electrical characters of SBD plasma excited by bipolar nanosecond pulse in atmospheric air