Number Of Voltage Research Articles

Dataset for Detecting the Electrical Behavior of Photovoltaic Panels from RGB Images

The dynamic reconfiguration and maximum power point tracking in large-scale photovoltaic (PV) systems require a large number of voltage and current sensors. In particular, the reconfiguration process requires a pair of voltage/current sensors for each panel, which introduces costs, increases size and reduces the reliability of the installation. A suitable solution for reducing the number of sensors is to adopt image-based solutions to estimate the electrical characteristics of the PV panels, but the lack of reliable data with large diversity of irradiance and shading conditions is a major problem in this topic. Therefore, this paper presents a dataset correlating RGB images and electrical data of PV panels with different irradiance and shading conditions; moreover, the dataset also provides complementary weather data and additional image characteristics to support the training of estimation models. In particular, the dataset was designed to support the design of image-based estimators of electrical data, which could be used to replace large arrays of sensors. The dataset was captured during 70 days distributed between 2020 and 2021, generating 5211 images and registers. The paper also describes the measurement platform used to collect the data, which will help to replicate the experiments in different geographical locations.

Identify Hardware Trojans Based on Delay Feature

Hardware Trojan detection is too difficult due to the reason that chip production chain is too long. An improved machine learning classification algorithm is proposed. First, the time delay signals of circuits under different voltages are collected, and then determine whether there is a Trojan horse in the circuit depending on the time delay. A polynomial regression algorithm is combined to fit the delay data, and Trojan horse feature library can be established based on the regression function. The experimental results show that the 19 different voltages of 2 000 groups of delay units are extracted to compare. When the number of voltages considered comprehensively is 19, its prediction accuracy reaches the highest 95.2%. The proposed classification and regression algorithms can improve the recognition accuracy and automation of the hardware Trojan.

A simplified methodology for mitigating the harmonics and common-mode voltage using multi-level inverters for renewable energy applications

ABSTRACT Multi-level inverters have outstanding construction, making it feasible to achieve high voltage levels with less THD value. These harmonics can be mitigated by decreasing the number of voltage switches and DC links in the modified cascaded H-bridge multi-level inverter. This research deals with the novel 15-level inverter and reducing the number of power switches. The proposed work consists of three simulation circuits, one with 10 switches and the second with 12 switches. The mitigation of harmonics, voltage stress, and common-mode voltage is achieved with the help of modifying the pulses of the switches in the proposed 10 switches topology. Additionally, a filter is applied at the terminal to reduce the overall THD value for variable AC load applications. The multi-level inverter can generate the high-level output with less harmonics, losses, and common-mode voltage with the help of low switching frequencies. These types of a multi-level inverters are used in renewable energy applications. Finally, the simulation of a 15-level novel inverter is carried out with the help of MATLAB/Simulink software and compared with the conventional cascaded H-bridge multi-level inverter. The total harmonics distortion for modified CHBMI with 12 switches with or without filter and modified CHBMI with 10 switches with or without are mitigated as 13.53, 6.91, 12.86, and 4.56, respectively, compared to the conventional method with 28 switches. The proposed method is implemented in the hardware to validate the simulated results of the proposed topology.

Dynamical analysis of early afterdepolarization patterns in a biophysically detailed cardiac model.

Arrhythmogenic early afterdepolarizations (EADs) are investigated in a biophysically detailed mathematical model of a rabbit ventricular myocyte, providing their location in the parameter phase space and describing their dynamical mechanisms. Simulations using the Sato model, defined by 27 state variables and 177 parameters, are conducted to generate electrical action potentials (APs) for different values of the pacing cycle length and other parameters related to sodium and calcium concentrations. A detailed study of the different AP patterns with or without EADs is carried out, showing the presence of a high variety of temporal AP configurations with chaotic and quasiperiodic behaviors. Regions of bistability are identified and, importantly, linked to transitions between different behaviors. Using sweeping techniques, one-, two-, and three-parameter phase spaces are provided, allowing ascertainment of the role of the selected parameters as well as location of the transition regions. A Devil's staircase, with symbolic sequence analysis, is proposed to describe transitions in the ratio between the number of voltage (EAD and AP) peaks and the number of APs. To conclude, the obtained results are linked to recent studies for low-dimensional models and a conjecture is made for the internal dynamical structure of the transition region from non-EAD to EAD behavior using fold and cusp bifurcations and maximal canards.

Experimental study on the influence of energy conversion in the process of load coal plasma breakdown

The variation of voltage and current waveforms of loaded coal plasma breakdown was investigated thorough an independently designed triaxial loading plasma breakdown system. Furthermore, the effect of breakdown times on the energy conversion and the propagation characteristics of cracks near electrode were discussed. The results show that the loaded coal will form an internal penetrative crack under plasma breakdowns, and with breakdown times increase, the micro cracks of coal surface and the size of the smash area near the positive electrode gradually expands. The voltage and current waveforms of loaded coal differ significantly from those of unloaded coal. With the increase of breakdown times, the pre-breakdown period decreases, the plasma period increases step by step, and the number of voltage and current oscillations increases. During each discharge of the loaded coal, change trends of the deposited energy are consistent, and the deposited energy keeps small level in the pre-breakdown period, then increases rapidly in the plasma breakdown period, and finally keeps stable. In addition, with the increasing number of breakdowns, the maximum deposited energy firstly decreases and then rises, and eventually reaches a plateau. The energy conversion efficiency shows the same tendency with the deposited energy.

A proposal on voltage dip regulation for the Dutch MV distribution networks

Voltage quality regulation has been an ongoing discussion in many countries in the world to set up a regulatory framework where also voltage dips are included in the national grid codes. Regarding voltage dips, the regulatory framework is useful for establishing the coordination between the network operators, the equipment manufacturers, and the customers. The voltage dip regulation can provide benefits for the involved parties. By defining the responsibilities for the network operators and the customers, it can help distribution system operators to evaluate the quality of supply voltage and to take possible measures when the number of dips exceed the reference values defined in the regulation. The regulatory framework can also help customers to make an economic analysis for choosing appropriate mitigation methods to reduce the expected economic damages caused by voltage dips. This article presents two approaches for classifying different types of voltage dips into various clusters. Using datasets of voltage dips from the Dutch MV networks, the paper also describes the methodology for setting limits on the number of voltage dips for the regulatory purpose.

An Energy‐Aware Voltage‐Frequency Island Partition Method for NoC

To deal with the issues of energy consump- tion for Network on chip (NoC), this paper proposes a method for partitioning an NoC architecture into multi- ple voltage-frequency islands to achieve low energy con- sumption. The method considers the number of Voltage- frequency islands (VFIs), delay and reliability as multi- constraints. A mathematical model for Integer linear pro- gram (ILP) algorithm is constructed and LPSolve is used to solve the issues of VFI partition. The validity of the VFI partition method is accurately verified for E3S and MMS. Simulation results show that the proposed method is more reasonable and smaller consumption can be a chieved while multi-constraints are met. This method can get less energy consumption from 33.6 % to 9.1% or 16.7% than those by the other methods.

Effective proliferation control of human cancer cells using electrical pulses

Since current cancer therapies do not work effectively for all patients, there is a pressing need for alternate, affordable, yet effective treatments for inoperable and chemo-resistant tumors. Presented in this paper are our investigations on the application of short duration (milli and micro seconds) electrical voltage pulses for the treatment of breast carcinoma. For this purpose, electroporation, a pulse power technology, was evaluated for its effect upon the viability and proliferation of human breast cancer cells using a number of voltages and pulse durations. The results indicate the promising potential of electrical pulses to effectively and economically enhance drug transport across the normally impermeable plasma cell membranes and to reduce proliferation.

Cross Pairing of Select and Data Voltages to Display Grayscales in Liquid Crystal Displays

Successive approximation technique (SAT) has select voltages of row waveforms paired up with data voltages of column waveforms to achieve the maximum selection ratio. Cross pairing of select and data voltages without compromising the selection ratio generates more rms voltages as compared to SAT. Grayscales can be displayed with less number of voltages in the addressing waveforms and less number of time intervals in a cycle as compared to SAT by cross pairing of select voltages with data voltages. Better brightness uniformity among pixels that are driven to same grayscale can be achieved by cross pairing because the width of the select pulses increases due to less number of time intervals in a cycle as compared to SAT. About 50% reduction in number voltages in row waveforms and column waveforms in addition to a 50% reduction in number of time intervals in a cycle can be achieved as compared to SAT by cross pairing select and data voltages.

Effect of Repeated Impulses on Transformer Insulation

Power transformer plays a vital role in electrical power system. Many of the transformer failures reported are due to insulation failure in windings. The sources of failures are mainly due to impulse overvoltages of different waveshapes and also due to repeated application of impulses. In this paper an attempt has been made to analyze the degradation of transformer insulation for repeated applications of different impulse voltages. As oil impregnated paper (OIP) constitute major insulation of transformer winding, detailed experimental analyses are carried out for OIP insulations using standard test cell for impulse waves of varying front times from 0.064 μs to 1.4 μs and tail times from 6.0 μs to 67 μs. Exponential mathematical models for the voltage-number (V-N) characteristics are derived and used for predicting the number of impulses that OIP can withstand for any wavefront and wavetail. The accuracy of the models are checked with the experimental values.

A novel rotor position estimation approach for an 8/6 solid rotor switched reluctance motor

Switched reluctance motor (SRM) is becoming popular due to its simple construction, low manufacturing cost, ruggedness and fault-tolerant capability. In conventional switched reluctance motor (SRM), rotor is laminated. But in solid rotor switched reluctance motor (SRM), rotor is not laminated, and it is suitable for applications where rotors are immersed in water environment. A stationary can arrangement is introduced between stator and rotor. In this research, an 8/6 solid rotor switched reluctance motor which is used in reactivity control mechanisms of nuclear reactors is considered as test motor. As solid rotor switched reluctance motor is suitable for working in water environments in nuclear reactors, rotor position estimation is the topic of interest. A new approach which adopts two-phase excitation method is presented for rotor position estimation. Four different artificial neural networks (ANNs) with 2-5-5-1 structure are trained to estimate rotor position. The main advantage of this approach is to minimize the required number of voltage and current sensors. The validity of the new approach is verified through online comparison of estimated and actual rotor position.

Cross-sectional comparison of insulation degradation mechanisms and lifetime evaluation of power transmission equipment

As the deregulation of the electric power industry moves forward, there is an increasing need for cost cutting and it is becoming exceedingly important to keep track of the residual life and identify the timing of replacement for power transmission equipment that has aged for several tens of years in the field. This paper, taking up the theme of "insulation degradation phenomena and lifetime evaluation for power transmission equipment", conducted cross-sectional comparison of different types of equipment although this kind of evaluation was made independently for these equipment types so far. This paper covered six types of equipment: gas insulated switchgear (GIS), gas insulated transformers, oil filled (OF) transformers, OF cables, crosslinked polyethylene (XLPE) cables, and power capacitors. As a result of examining the characteristics such as electric, thermal, mechanical, and hygroscopic degradations, each of these equipment types was found to have distinctive Voltage-time (V-t) and Voltage-number (V-N) characteristics, which sometimes greatly varied from those of others. Since thermal degradation is dominant for gas insulated transformers and oil filled transformers, their lifetimes depend on the reduction of mechanical strengths of Polyethylene Terephthalate (PET) or insulating paper. Therefore, it is effective to diagnose decomposition products such as CO, CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and furfural generated in the thermal degradation mechanism. On the other hand, the influence of electric degradation has more significant impact on the other equipment types except OF cables. Such GIS components as epoxy spacers, XLPE cables, and power capacitors for which long-term ac voltages are dominant, are commonly characterized by the long-term V-t characteristics with a large gradient (small n-value). In terms of insulation structures, there is a possibility of reducing the degree of degradation by improving solids or the interface between solids and electrodes.

Voltage-time and voltage-number characteristics of insulation elements with large scale oil-immersed transformers under field-use conditions

In order to attain reduction in insulation test voltages, voltage-time (V-t) characteristics for ac voltage and voltage-number (V-N) characteristics for lightning impulse voltage were experimentally investigated on the turn-to-turn insulation model, coil-to-coil insulation model and barrier-oil-duct insulation model of core- and shell-type transformers under non-standard of field-use conditions. The conditions used for experiments on insulation characteristics in view of field-use consisted of "clean oil" and "hot oil" as the conditions for insulating oil, "trapezoidal waves", "alternate applications of positive and negative voltages", and "steep front waves" as the conditions for applied voltages, and "low dielectric constant pressboards" as an insulating object in experiments. Although the measured V-t and V-N characteristics varied depending on the conditions, the total evaluation in terms of insulation coordination showed that results under standard conditions were satisfactory in almost all the cases and some cautionary points in a few cases were recognized

Voltage-time and voltage-number characteristics of insulation elements with oil-filled transformers in EHV and UHV classes

In order to attain reduction in insulation test voltages, voltage-time (V-t) characteristics under AC voltage and voltage-number (V-N) characteristics under lightning impulse and switching impulse voltages were experimentally investigated on the turn-to-turn insulation model, section-to-section insulation model and barrier-oil-duct insulation model of core- and shell-type transformers in EHV and UHV Classes. First, V-t characteristics for AC voltage were obtained in a short time range of a few tens of milliseconds to a long time range of three to four months. The n-values (inclination) of V-t characteristics are distributed around 40 for the short time and several hundreds for the long time characteristics. These values are of essence in determining the AC withstand voltage test. Next, V-N characteristics for both lightning and switching impulse voltages were acquired for up to 1,000 times of application. The n-values (inclination) of V-N characteristics are in most cases distributed around 70 for both impulse waveforms and about 40 in only turn-to-turn insulation models This result will be useful for evaluating the effect of frequent surges on apparatus insulation. Finally, insulation coordination studies were performed based on these experimental results.

Frequency representations of one‐port networks

PurposeAnalysis of harmonics propagation in power systems requires information about models of non‐linear loads which are the main source of harmonics. The purpose of the paper is to present a method of parameter determination of non‐linear loads.Design/methodology/approachA method of parameter determination of a model has been described in the article. This method has been developed assuming that mathematical description of a non‐linear load is known. In order to obtain a harmonic representation of this model for one‐phase loads the theory of harmonic balance method has been used.FindingsParameters of the current or voltage controlled sources can be expressed as a function of any number of voltage or current harmonics. In the case under consideration the network input current is a function of input voltage and its derivatives. Thus, contrary non‐linear element with inertialess characteristics, the first harmonic of the current depends not only on amplitude but also on frequency of the voltage across terminals of one‐ports.Originality/valueThe method presented in the paper enables relatively simple determination of frequency parameters of non‐linear models of one‐port networks.

Generalized gyrator implementation techniques using unity-gain cells

All possible gyrator circuits using the minimum number of voltage and current unity-gain cells are extracted, as a result of generalizing the unity gains, such that a unity gain can be + 1 or −1. Since second-generation current conveyors (CCIIs), possessing both voltage and current unity-gain cells, are very suitable for such gyrators, it is shown that inclusion of the recently proposed ‘inverting secondgeneration current conveyor’ (ICCII) in the design enables implementation of all types of extracted gyrators. The number of possible gyrator configurations is eight, one of them being the well-known Sedra–Smith gyrator and another its x -input counterpart; both utilize only CCIIs. The remaining possible six gyrators are new and utilize ICCIIs as well. Like the Sedra–Smith gyrator, all the circuits employ a minimum number of passive elements and similar types of active components, namely CCIIs and/or ICCIIs. The effects of current conveyor non-idealities and parasitics on important gyrator applications are also investigated. A highperformance dual-output CMOS ICCII is designed and used in SPICE simulations of two important gyrator applications in order to verify the theoretical results. Also, as a design example, an elliptic filter is realized and simulated.

Relay performance in DSG islands

During field tests to confirm the existence of ferroresonant conditions in distribution system generators (DSGs), a number of voltage and frequency relays were installed and their performance monitored while exposed to the highly distorted waves resulting from these conditions. While the general performance of relay groups was satisfactory, certain problem areas became apparent. The field tests and evaluation method are described, the test results are reported, and the problem areas are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An Optimal Load Dispatch Program Using a Fast Power Flow Technique

ABSTRACT This paper presents a new technique of Economic Dispatch for allocating generation in a power system. Penalty factors associated with generating units are calculated from a particular eigenvector of the transposed Jacobian matrix which is obtained while solving the load flow problem using a modified version of the fast power flow method developed earlier. The evaluation of the required eigenvector is simple and straightforward as the order of the Jacobian matrix is equal to the number of voltage controlled busbars in the system. The optimal allocation of each generating unit for the given demand on the system is obtained by solving the co-ordination equations along with load flow problem. The technique is found to be fast, reliable and suitable for on-line implementation.

Multicomputer Control of System Voltage and Reactive Power on Real-Time Basis

This paper concerns a real-time control scheme of voltage and reactive power in power systems when more than two control computers as well as one central coordinating computer are involved. When a large number of voltage and/or reactive power regulating devices are involved in a power system and the number of nodes or lines in which the voltages or reactive power flows are observed and controlled increases, the necessary computing time and memory requirement increase exponentially if the central computer installed at the central dispatching office should take care of all control functions. In addition, the number of channels of the data transmission network becomes very large because the voltage and reactive power flow at each electric station must be transmitted to the central computer and the optimum operating values of regulating devices should be transmitted back to the regulating stations.

Experiments on the Elastic Single Scattering of Electrons by Nuclei

Experiments on the elastic single scattering of electrons by nuclei are described, the measurements extending over a range of voltages, angles, atomic numbers, and foil thicknesses. Observations were made at a number of voltages from 1.27 to 2.27 Mev and at angles from 20 degrees to 50 degrees on both sides of the incident electron beam. The scattering foils were aluminum, copper, silver, platinum, and gold, the atomic numbers thus varying from 13 to 79. When the foil thickness exceeded that for a "thin" target, a correction was made for multiple scattering. The use of an accurately focused homogeneous beam of electrons from an electrostatic generator made possible clear-cut control of the basic experimental variables. The experimental method was designed to minimize the effect of x-ray background, etc. The present results are in close agreement with the relativistic theory of electron scattering, as developed by Mott, over the entire range of the experimental variables except for the case of 2.27-Mev electrons on aluminum. Excepting only this case, the average of all the ratios of experimental result to theoretical prediction is 1.01 with a standard deviation of 0.06. This is in marked contrast with most of the previous work in this field where results have been widely divergent. The results of this paper, combined with spectroscopic data, extend the range of validity of the Coulomb law of attraction between electron and nucleus in close to the surface of the nucleus. The measurements of the scattering of 2.27-Mev electrons by aluminum will be repeated as soon as circumstances permit, as these results now indicate for the larger angles an interesting divergence from theory.