Neutral Ground Research Articles

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.

High-Voltage Shore Connection Systems: Grounding Resistance Selection and Short-Circuit Currents Evaluation

Cold ironing represents an effective solution to remove air polluting emissions from ports. The high voltage shore connection system is the key enabling facility that allows to provide power from the shore side electrical system to the ship. The design of the shore connection needs a comprehensive assessment of the fault currents in different operating scenarios. International standards require the neutral point of the shore connection transformer be equipped with a neutral grounding resistor. Its value has to be defined to guarantee safety and protection of equipment and personnel in case of single phase-to-ground faults. Moreover, three-phase short circuits need to be considered to size equipment and protection devices. A crucial role is played by the frequency converter control system, required to adapt the mains frequency to the frequency of the ship. In this work, a complete electro-magnetic dynamic model of the high voltage shore connection and of the on-board power system has been developed, including frequency converter, shore-side transformer, connection MV cables and power system of the ship, to analyze in detail the behavior of the system in case of single phase-to-ground fault and three-phase short circuit, taking into account relevant standards and best practices.

Complex energies and transition dipoles for shape-type resonances of uracil anion from stabilization curves via Padé.

Absorption of slow moving electrons by neutral ground state nucleobases has been known to produce resonance metastable states. There are indications that such metastable states may play a key role in DNA/RNA damage. Therefore, herein, we present an ab initio non-Hermitian investigation of the resonance positions and decay rates for the low lying shape-type states of the uracil anion. In addition, we calculate the complex transition dipoles between these resonance states. We employ the resonance via Padé (RVP) method to calculate these complex properties from real stabilization curves by analytical dilation into the complex plane. This method has already been successfully applied to many small molecular systems, and herein, we present the first application of RVP to a medium-sized system. The presented resonance energies are optimized with respect to the size of the basis set and compared with previous theoretical studies and experimental findings. Complex transition dipoles between the shape-type resonances are computed using the optimal basis set. The ability to calculate ab initio energies and lifetimes of biologically relevant systems paves the way for studying reactions of such systems in which autoionization takes place, while the ability to also calculate their complex transition dipoles opens the door for studying photo-induced dynamics of such biological molecules.

Nonlinear Modeling Analysis and Arc High-Impedance Faults Detection in Active Distribution Networks With Neutral Grounding via Petersen Coil

For Arc High-Impedance Faults (AHIFs) in Active Distribution Networks (ADNs) with neutral grounding via Petersen coil, both nonlinear characteristics caused by arc and the influence of zero-input response have been not considered in previous research. Quantitative analysis methods based on the threshold setting comparison is mostly adopted in current field applications, which cannot balance the detection reliability and sensitivity simultaneously. In response to this problem, a higher precision nonlinear AHIF equivalent model is established based on the logarithmic arc model. State equations describing the occurrences of AHIFs are solved by using piecewise linear fitting technique, and analytical expressions of zero-sequence voltage and currents are present in paper. Furthermore, the regular volt-ampere characteristic dynamic trajectory between the zero-sequence voltage and current in characteristic frequency band is analyzed, and a tangent-inverse method is proposed to extract the direction of dynamic trajectory, then an effective fault detection algorithm is designed. The validity of the proposed nonlinear equivalent model and detection algorithm are verified by various cases’ simulations and field test data.

Practical Charts for Sizing Neutral Grounding Elements for Machine-Based Distributed Energy Source Step-Up Transformers

One of the challenges resulting from the adoption of machine-based distributed energy resources lies within the intersection of protection and performance grounding. These are strongly interrelated and conflicting subjects that dictate the occurrence of ground fault overvoltage and the effectiveness of ground overcurrent protection. Currently, there remains a gap in the distribution planning of most jurisdictions in formulating these aspects and adopting simple and practical measures to balance these subjects. This letter introduces a simulation-based method to develop a set of practical charts intended to be used as a sizing guideline for neutral grounding elements, which are to be employed in the associated step-up transformers. This solution became pivotal to the electrical utility conducting the research and has allowed planning engineers to simplify design and streamline cooperation between the utility and large-scale DER developers.