Neutral Ground Research Articles

A Novel Neutral Point-Based Active EMI Filter for Common Mode Noise Attenuation

This paper proposed a new configuration of neutral point based common mode (CM) active EMI filter (NP-CM-AEF). It is achieved by setting the reference of filtering system to the neutral point of equipment under test (EUT). Therefore, CM noise could be sensed across neutral point and ground. Meanwhile, compensation signal could be built by op-amp and re-injected to cancel the initial CM noise. The main advantage of the proposed NP-CM-AEF lies in that no more noise separation such as bulky passive CM transformer is needed to get pure CM noise. The whole filter becomes smaller, lighter and more compact compared with traditional CM AEF. Working principle is analyzed in details and hardware experimental tests are also performed. It shows that the proposed NP-CM-AEF has a good attenuation to CM noise and total size is pretty tiny.

Study of Iran–Saudi Arabia Sports Relations

Political tensions and conflicts have been accompanying modern sports for a long time. The objective of this study was to determine the political reasons for not hosting football matches between Iranian and Saudi football teams. To address the research objective, a mixed-method approach was used. First, in the qualitative part, the political reasons for not hosting the matches identified through the content analysis and interviews were reviewed and evaluated by Delphi Group (25 people) in the second and third stages. Secondly, in the qualitative section of the study, the questionnaire was also used to rank the reasons. The research findings showed that tensions between Tehran and Riyadh increased after the Saudi Embassy attack in Tehran and Mashhad (January 2016) and the execution of Sheikh Nimr, a Shia sheikh opposed to the Saudi government. Saudi Arabia has requested that the Asian Champions League matches against Iranian opponents be held on neutral grounds in order to ensure the safety of its players. It is therefore recommended that sports managers and politicians in Iran reduce the political tensions between the two countries. In addition, they need to strive toward creating peace, friendship, and security between the two countries.

A Hybrid Flexible Neutral Grounding Mode for Large Generators

Single-phase ground faults frequently occur at the generator stator windings. To realize reliable arc suppression, a dual-frequency active arc-suppression strategy has been widely considered. However, the existing method needs an inverter with large capacity, which is large in volume and high in cost, causing limited engineering application prospects. To reduce the capacity, a novel hybrid flexible neutral grounding method for large generators is proposed in this paper. It combines the dual-frequency active arc-suppression strategy with the arc-suppression coil-grounding mode. Thus, most of the fundamental components in the fault current are compensated by the arc-suppression coil, and the rest are compensated by the active arc-suppression device. The capacity of the inverter can be greatly reduced under the premise of reliably realizing arc suppression. To identify transient and permanent ground faults after arc suppression, the phase-angle relation between the third-harmonic voltage and current variation at the generator neutral point is used to form the fault-type identification criterion. The third-harmonic quantities can avoid the blind area at the neutral point caused by fundamental quantities. Simulation and experimental test results verify the effectiveness of the proposed method.

An Innovative Shielding Strategy for Stray Loss Reduction of Neutral Grounding Reactor

Leakage fluxes formed by power equipment are one of the serious concerns of the electricity industry. Stray losses, which are a consequence of leakage fluxes, can lead to thermal stresses in metallic parts and dramatically reduce the life of the equipment. To alleviate this obstacle, this article aims to deploy a new approach to mitigate the stray losses in structural parts. This method is based on electric and magnetic shielding to deviate or bypass the stray fluxes and abstain from hot spots. Computation of stray losses inside the shields and other metallic structures is conducted using 3-D finite element analysis (FEA). To determine the dimensions of shields, various contingency simulations are implemented. A 0.51 MVAr, air-core, oil-immersed neutral grounding reactor (NGR) is considered as a case study to verify the effectiveness of the presented method. The performance of the suggested shield arrangement has been experimentally investigated, and the obtained results present an indication of a best-suited design with respect to performance and size.

Electron-impact ionization cross sections of small molecules containing Fe and Cr ∗ ∗ This work is dedicated to Enrico Clementi who pioneered the interdisciplinary use of quantum chemistry and computational modelling.

We present the electron-impact ionization cross sections (EICSs) of iron and chromium hydrides, nitrides, and oxides. The motivation of this work stems from the fact that chemical sputtering from a steel surface exposed to a hot plasma can create these molecules which in turn influence the composition and energy balance of the plasma. The latter influence is quantified by the EICS which we derive by using two semi-empirical methods which can be employed in the relevant energy range of 10–1000 eV. They are important molecular properties for plasma- and materials science. We discuss the foundations of the methods and present the cross sections of the high- and low-spin states of the species in their neutral ground states and of their cations.

Study on Dynamic Characteristics of Single-Phase Grounding Fault of 1000 MW Hydro Generator under Different Grounding Modes

The continuous operation of 1000 MW large hydro generators in China is of great value to the implementation of “double carbon strategy” and power grid safety. However, with the continuous increase of single unit capacity of the hydro generator, the problems of unit fault grounding current and neutral point voltage drift become more and more prominent, and the traditional analysis methods cannot accurately obtain the fault dynamic data. Therefore, starting from the neutral point grounding mode of the large hydro generator, taking a 1000 MW hydro generator as the research object, this paper establishes the single-phase grounding fault model under the condition of three-phase parameter asymmetry of stator winding and analyzes the dynamic characteristics of fault current, transient overvoltage, and neutral point voltage drift under different grounding modes by using transient analysis method; the influence of frequency offset on neutral voltage drift and the dynamic characteristics of single-phase grounding fault of the large hydro generator under different grounding modes are also obtained. Finally, according to the analysis results, the selection and optimization method of neutral grounding parameters are proposed, which provides a reference for the selection of neutral grounding mode and the research of protection strategy of the large hydro generator.

Drastic effects of an inert Pt wire on the redox behavior of the Belousov-Zhabotinsky reaction.

This research investigated responses of the Belousov-Zhabotinsky (BZ) reaction to the presence of a chemically inert Pt wire in solution. Experiments showed that connecting the Pt wire to a neutral ground caused a spontaneous drastic shift in the redox potential and might even induce complex behavior. Characterizations using an unstirred ferriin solution demonstrated the formation of a red colored propagating front at the grounded Pt wire, suggesting the reduction of ferriin to ferroin. Measurements with different combinations of electrodes in both stirred and reaction-diffusion media further confirmed the reduction of BZ metal catalysts at the Pt wire and the accompanying oxidation reaction at the reference electrode. The observed drastic change in redox potential and oscillation waveform can be understood based on the passive reduction reaction at the indicator electrode that is connected to the reference electrode through a potential meter. The obtained influence can be further manipulated by adding a resistor between the Pt wire and the neutral ground, making this convenient perturbation method attractive for the study of redox chemical reaction dynamics.

Photoionization spectroscopy of the SiH free radical in the vacuum-ultraviolet range.

The first measurement of the photoelectron spectrum of the silylidyne free radical, SiH, is reported between 7 and 10.5eV. Two main photoionizing transitions involving the neutral ground state, X+1Σ+ ← X2Π and a+3Π ← X2Π, are assigned by using ab initio calculations. The corresponding adiabatic ionization energies are derived, IEad(X+1Σ+) = 7.934(5)eV and IEad(a+3Π) = 10.205(5)eV, in good agreement with our calculated values and the previous determination by Berkowitz et al. [J. Chem. Phys. 86, 1235 (1987)] from a photoionization mass spectrometric study. The photoion yield of SiH recorded in this work exhibits a dense autoionization landscape similar to that observed in the case of the CH free radical [Gans et al., J. Chem. Phys. 144, 204307 (2016)].

Vocal Depersonalization in Scat Singing

"The purpose of this paper is to question the amount of personal investment in exploring the voice as an impersonal sound, in scat singing. Jazz singers and jazz voice teachers follow vocal practices that aim to control and distort the vocal timbre, to master microtonal intervals, to push and eventually overcome the voice’s limits. In scat singing, the boundaries of gender are subdued to the impulse of improvisation, thus, even though the timbre is a biological and a physical memory, influenced by the singer’s culture and experiences, the gender encoding can be reshaped inside the licks and patterns of the improvisation section. The current paper aims to prove that scat singing is the neutral ground where aspects of the voice can blend and disappear into one another: voice gender, vocal timber, technique, individual materiality, experimentation. Keywords: scat, improvisation, jazz, vocalists "

Implementasi Parameter Sistem Pentanahan Generator Melalui Transformator Distribusi Menggunakan Labview

Determination of the generator neutral grounding system through a distribution transformer can be done through manual calculations. Many parameters are considered in the calculation to get the appropriate results there is the possibility of repeated calculations. This is very difficult and causes a large difference in the calculation results. Therefore, a computer-based computing system is needed to overcome this kind of problem. Several papers have developed the calculation of the required generator neutral earthing magnitude which considers the voltage level, short-circuit fault current and protection system against ground faults. This paper discusses modeling in designing generator neutral ground using the LabView Graphical User Interface (GUI) application. The goal is to be easier, faster and more accurate. As the implementation of the modeling used data from std C62.92.2TM-2017.

Power system neutral point grounding

The method used for neutral point grounding is very important for power network operation. There are many ways of grounding, which are used in practice, and the decision on the method of neutral grounding depends on the situation in the network connected to the substation. When deciding on the method of neutral grounding it is necessary to thoroughly consider all the advantages and disadvantages of individual modes of neutral grounding, and then choose the best technical and economical solution. This paper analyzes the ways of neutral point grounding in medium voltage networks used in the current practice in Croatia which are isolated neutral point, low resistance earthing, partial compensation and resonant earthing. The use of shunt circuit-breaker is also described. Additionally, a survey of the relays used for the neutral point grounding system inside the substations was conducted and a brief analysis of the results is presented in the paper.

Technical Solutions for Preventing the Development of Single-Phase Ground Faults and for Eliminating Them in 6–10 kV Power Plant Switchgears

The severity of the consequences from single-phase ground faults (SPGF) at the combined heat and power plants (CHPPs) operating as branches of PJSC Mosenergo is due to the following two main reasons: prolonged exposure to overvoltage and a significant wear of primary electrical equipment. The operation mode with a compensated neutral assumes setting up conditions for arc self-extinguishing at the SPGF location; however, in the majority of cases this does not happen. The practice of continuing the operation with an SPGF for several hours has a negative impact on the power plant electrical equipment and needs to be revised. To evaluate the influence of an SPGF in a 10 kV network on the reliability of power plant operation, the main electrical connection circuits and the adjacent network at 12 CHPP branches of the Mosenergo company is analyzed. The basic technical solutions aimed at preventing the development of and eliminating SPGFs in the 6–10 kV CHPP network are considered. In carrying out the analysis, the overvoltage modeling results were used with taking into account the feasibility of implementing various solutions at power plants. Based on the analysis results, the possible technical solutions have been divided into more and less efficient ones. For the majority of CHPPs, an efficient solution implies the transition from the compensated neutral grounding mode with holding an SPGF for a long period of time to low-impedance resistive neutral grounding with clearing the fault by the action of relay protection and automatic control devices

Co-Evolution of Organizations in Infrastructure Planning: The Role of Communities of Practice as Windows for Collective Learning Across Project-Oriented Organizations

Challenges in infrastructure planning require public infrastructure administrators, responsible for providing adequate infrastructure facilities, to be adaptive. These organizations evolve and interact with other organizations in a complex organizational landscape. This paper explores the contribution of inter-organizational communities of practice (CoPs) to collective learning and co-evolution of organizations in infrastructure planning. We conducted a case study of five inter-organizational CoPs in the domain of a typical public infrastructure administrator. The results suggest that inter-organizational CoPs enable, for example, policy and practice to co-evolve. Inter-organizational CoPs seem to provide a neutral ground where long-term sector benefits can overcome short-term organizational interests.

Results From Changes in The Pole of 15 kV Power Transmission Lines

Baganuur Southeast Electricity Distribution Network 15 kV electrical transmission line interruptions research was conducted, and a factor analysis was performed to determine the conditions of the line outage. Due to the neutral grounding of the 15 kV electrical transmission line and the relatively small distance between the line wires and crossbar, there is a high incidence of grounding during the landing and flight of birds, which hurts the reliable operation and ecology of the line. Therefore, the structure of the poles changed, and the results are reflected.

Analysis of fault current and overvoltage at the neutral point of [formula omitted]800 kV High-Voltage DC converter transformer

In order to enhance the security of ±800 kV High-Voltage DC (HVDC) system, it is needed to consider and analyze the grounding mode of the neutral point of converter transformer. Different neutral grounding modes have different inhibitory effects on the current of transmission lines when faults occur, and also produce different overvoltages at the neutral point. Therefore, this paper first analyzes the influence of converter transformer on fault current and neutral point voltage in three cases of ungrounded, direct grounding and via small reactance grounding. Through the analysis, it is known that the neutral grounding via small reactance is the most suitable for the HVDC transmission system. Then the model of ±800 kV bipolar HVDC transmission system is built in PSCAD/ EMTDC simulation software and analyzed under two typical conditions of grounding overvoltage and breaking overvoltage. By comparing several cases of converter transformer neutral point grounding directly, via 5Ω, 10Ω, 17Ω, 20Ω and 25Ω reactance grounding, it is found that grounding via small reactance can effectively suppress fault current. However, with the increase of the resistance value, the inhibitory effect will gradually weaken and cause the increase of the neutral point overvoltage.

Resetting the ground fault relay on a 28 MVA power transformer due to grounding method retrofit

The goal of the retrofit at Zamrud substation is to transform a 28 MVA power transformer’s neutral point grounding system from direct grounding to grounding using a 20 Ohm Neutral Grounding Resistor (NGR). The amount of short-circuit current produced will fluctuate with the installation of NGR. It is necessary to re-setting the Ground Fault Relay (GFR) on Zamrud substation. To estimate the value of the short-circuit current after installing the NGR, the impedance matrix approach is used to calculate it. According to the results, LG’s largest short-circuit current is 397.83 A and its smallest is 313.55 A. Meanwhile LLG has a maximum short-circuit current of 5.334.30 A and a minimum short-circuit current of 943.31 A. Therefore, after NGR installation, the value of the relay setting is as follows: GFR pickup current on the transformer grounding GFR relay is 234.29 A, GFR pickup current on the neutral feeder 1 is 19.96 A, GFR pickup current on the neutral feeder 2 is 30.42 A, and GFR pickup current on the neutral feeder 3 is 38.40 A.

A Systems Approach to Behavioral Neurobiology: Integrating Psychodynamics and Neuroscience in a Psychiatric Curriculum

In the practice of medicine, an understanding of the biological functioning of organs and organ systems is the basis for theories of pathology and clinical practice. If psychoanalysis is to be accepted by the medical and psychiatric community, it must be based on a sophisticated understanding of the organ from which mental and emotional experiences emanate and use scientifically acceptable language. Each approach to psychotherapy has its own vocabulary for describing neuropsychological processes. Neurobiological vocabulary provides the various factions "neutral ground" upon which to carry on a multidisciplinary integrative dialogue. An understanding of behavioral neuroscience allows the therapist to look beyond the labels that spawn division and identify unifying biological principles that are described in a variety of ways in a multitude of theories. We contend that the neural network/representational approach to neurobiology views human mental experience as the result of multiple complex integrated systems, and is therefore holistic and antireductionistic in its perspective. Such a biologically informed psychotherapy facilitates integration of skill sets and flexibility in technique. With these principles in mind, the therapist can base his or her approach to the patient based on these principles rather than on devotion to one particular "school" or another. Because behavioral neuroscience supports many of the basic tenets of psychoanalytic theory, such an integrative psychotherapy would be psychody-namically informed. In this paper, we outline some of the ideas we present in our neuroscience course and how we relate biological concepts with some core principles of psychodynamics and psychotherapy.

Single-phase disconnection fault location of active distribution network based on negative-sequence differential impedance

Accidents such as overvoltage, personal injury and motor damage caused by singlephase disconnection faults occur frequently in active distribution networks. In response to this problem, firstly, the negative-sequence differential impedance is defined and a protection method based on negative-sequence differential impedance is proposed, the method uses the amplitude of negative-sequence differential impedance as an action quantity and uses its phase to construct an adaptive braking threshold. Secondly, in case of protection failure under overload, the zero-sequence voltage amplitude difference is proposed as an auxiliary criterion, and the influence of different types of distributed generators on the zero-sequence voltage difference on both sides of the fault fracture is analyzed. Finally, it is verified by simulation that the method can be positioned reliably and is not affected by the neutral point grounding method, transition resistance, load and distributed generators.

Evaluation of lightning overvoltage at neutral point of HVDC converter transformer based on EMTP

In order to ensure the safe and stable operation of high voltage direct current (HVDC) systems, this paper studies the lightning overvoltage at the neutral point of the HVDC converter transformer. The work first introduces the basic types of lightning overvoltage based on the CIGRE Benchmark 500 kV HVDC transmission system which is modeled in the electromagnetic transient program (EMTP) software. The high-frequency model of the HVDC transmission system is considered where lightning overvoltage at the converter transformer neutral point is studied at different values of the small reactance connected at neutral point grounding and different lightning strike locations. Although increasing the small reactance value can effectively suppress the lightning current, the lightning overvoltage will gradually increase. When the neutral point is grounded by 11 Ω small reactance, the lightning overvoltage is most serious, where the peak value can reach 415 kV. Also, the farther the lightning strike position from the converter transformer, the smaller the lightning overvoltage.

Flexible Grounding System for Single-Phase to Ground Faults in Distribution Networks: A Systematic Review of Developments

The neutral grounding method is one of the crucial technologies used to ensure the safe and stable operation of distribution networks. With the development of power electronics-based devices, the application of highly controllable inverters to grounding systems has become a new research direction. In this review paper, based on the summary and analysis for the research status, the flexible grounding system is systematically classified according to its control strategy and structure. And then, the following core technologies are summarized: faulted line selection, current component detection, high-resistance ground identification, ground parameter measurement, neutral point voltage control, and fault location. Subsequently, deficiencies of flexible grounding systems are summarized from the following four perspectives: reliability, accuracy, speed, and stability. Finally, some discussions and recommendations for future development and research direction are presented. Especially, the reliability-enhanced hybrid grounding system that combines active inverters and low resistance for high-resistance ground faults is recommended. This paper provides a systematic literature review of the crucial technologies for flexible grounding systems and can be used as a technical reference for future research.