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Under the same conditions， the ground capacitance of high-voltage AC submarine cables is over 20 times greater than that of overhead lines， making resonance phenomena more likely during no-load closing of submarine cables. This paper addresses an incident during the no-load closing of a 500 kV AC submarine cable in an offshore wind farm， where resonance caused a malfunction of the line differential protection. The paper analyzes the fault recording data and investigates the resonance mechanism during the closing process based on circuit theory. Simulation results indicate that the incident was caused by the integration of long-distance high-voltage AC cables into a weak system， leading to resonance overcurrents that were below 1.5 times the power frequency but of high magnitude. Despite current compensation from the protection device， significant capacitive resonant differential currents remained， resulting in the malfunction of the differential protection. In light of the engineering context， the paper proposes a response strategy that optimizes the wiring of the secondary circuit of the protection device and dynamically adjusts the threshold for differential current action based on system conditions and the magnitude of line capacitive currents. Finally， the effectiveness of the proposed countermeasures is validated through RTDS closed-loop testing.

Copyright of Zhejiang Electric Power is the property of Zhejiang Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Modern distribution networks have constantly evolved to meet different requirements. Basically, increasing energy demand and supply security are the main motivation for these changes. In order to meet the increasing energy need, there are many parallel outgoing feeders in the distribution substations, and there is an intense use of underground cables to increase supply security. During single line to earth fault, zero sequence currents circulate in the system due to cable capacitive currents of underground cables. These capacitive charging currents may cause false trips in healthy sections of the network. Metropolitan distribution networks draw particular attention with distinguishing topological features which are; the usage of long-length underground cables and high number of parallel outgoing feeders. In addition, different types of earthing methods are applied. This situation eliminates the applicability of simple, unique and universal relay settings for all types of networks. As a result, the requirement of feeder-based protection hybridization, specifically tailored to the distribution network topology is inevitable. In this study, feeder-based hybrid protection methods and optimum setting values of these methods are proposed for different network topologies and different neutral earthing methods. The method-hybridization is applied to the 62-busbar distribution network to demonstrate the applicability of the proposed method. [ABSTRACT FROM AUTHOR]

The electroanalytical methods have been developed for wide application, especially for trace metal ions. In this study, the applicability of 1-butyl- -3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) ionic liquid as a pasting binder to fabricate a multi-walled carbon nanotube paste electrode (MWCNT PE) for detecting Pb2+ and Cd2+ was evaluated. The electrochemical properties of electrodes were explored by cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep anodic stripping voltammetry. The use of [BMIm][PF6] alone as a conductive binder resulted in an electrode that was unsatisfactory for electrochemical analysis. However, the MWCNT PE with the pasting mixture of silicon oil and [BMIm][PF6] displayed excellent sensitivity for the Pb2+ and Cd2+ determinations, with limits of detection of 2.25 and 1.59 g L-1, respectively. The proposed electrode was demonstrated to be a reliable sensor for accurately quantifying trace amounts of Pb2+ and Cd2+, exhibiting good repeatability, reproducibility and stability.

This paper examines the compensation of capacitive currents using arc suppression reactors with magnetization. A method is developed for automatic tuning of an arc suppression reactor for improving the accuracy and reliability of the results of measurements of the capacitance of the zero sequence loop. These problems are solved by measuring and recording the frequency spectra of the neutral voltage using the fast Fourier transform before and after perturbation of the zero sequence loop by a reference current of short duration through a signal winding of the arc suppression reactor. After this, the difference in the obtained frequency spectra is isolated and the proper frequency of the zero sequence circuit is determined from the maximum amplitude corresponding to the frequency of the free oscillations. The found frequency for a known inductance of the arc suppression reactor is used to determine the capacitive impedance of the network and the required magnetization current. [ABSTRACT FROM AUTHOR]

Due to the loop distance of double circuit transmission line on the same tower is small, the electromagnetic coupling and electrostatic coupling between the power failure line and the running line are greatly enhanced, and higher induced current and induced voltage are generated on the power failure line. At the same time, the line is erected without transposition, the line’s three-phase parameter is asymmetrical, and the induced current and induced voltage show obviously phase separation characteristics. The paper apply transient simulation software EMTP to simulate the induced current and induced voltage under different line lengths, transmission power flow and phase sequence arrangement, which provides a reference for the design, planning and operation of 500 kV double lines on the same tower in the regional power grid.

The arc suppression coil determines whether it can effectively extinguish the arc when it is grounded in the neutral non-effective grounding system. An artificial grounding test is an importantway to verify its performance. In this study, 13 substations with the 10 kV system in the Ningxia areawere selected and considered. Based on the artificial single-phase grounding test, the residual current, the compensation current and the off-resonance degree were measured in the arc suppression coil, and the performance of the arc suppression coil in the 10 kV system was verified. The experimental results show that the error of arc suppression coil automatic measurement is large, the off-resonance degree is large, the resistive component in the compensation current is excessive, the harmonic component exists in the compensating current and capacitive current. To solve these problems, this paper puts forward the corresponding countermeasures for reference.

Background: We obtained microelectrode recordings from four patients with intractable aggressivity who underwent surgery at posteromedial hypothalamus under general anaesthesia. We described two general types of extracellular action potentials (EAPs): typical/canonical and atypical. Methods: We analysed 337 units and 67 traces, which were characterized by the mean action potential (mAP). For the first phase, depolarization and repolarization, we computed amplitudes (VFP, VDep and VRep) and durations (dFP, dDep and dRep), maximum and minimum values of the first derivative (dVmax, dVmin), and amplitude and duration ratios. Results: Most of the canonical mAPs were positive (81.1%). EAPs with atypical mean action potentials (amAPs) were recorded in 42/337 cases. Only 35.6% of mAPs showed 2 phases. We identified the following types: N1P1N2 (38.3%), P1N1 (35.9%), amAP (12.5%), P1P2N1 (12.2%), N1P1 (4.7%), P1N1P2 (4.1%) and N1N2P1 (3.2%). We can define the properties of canonical forms as those units with (i) at least two opposite phases; (ii) VDep∈[1.2,2.7]×|VRep| and strongly related by this function VRep=-0.56⁢(±0.01)⁢VDep-1.83⁢(±0.79); (iii) a very strong relationship between dVmax and dVmin, given by the equation d⁢Vmin=-0.91⁢(±0.03)⁢d⁢Vmax-0.37⁢(±0.12), both of which were included in the depolarization phase; (iv) related with VDep by the equation d⁢Vmax=0.08⁢(±0.001)⁢VDep-0.28⁢(±0.14); and (v) dDep⁢~⁢0.38⁢dRep. However, the first phase does not pertain to the same dynamic process responsible for depolarization and repolarization. Conclusions: Atypical units are described here for the first time and are true EAPs that differ strikingly from canonical forms. To date, they have been observed only in the hypothalamus, but future research is needed to assess their existence in other brain structures.

The influence of capped gold nanospheres (GNSs) on the direct current (DC) electric conductivity ( σ D C ) of a ferroelectric liquid crystal (FLC) confined in a cell with blocking electrodes was experimentally investigated. In framework of this work, several measurement techniques of σ D C , such as dielectric and conductivity spectroscopies, were utilised. However, it was demonstrated that only the capacitive technique allowed estimating values of σ D C of both pure FLC and FLC/GNSs nanodispersion confined in the cell with blocking electrodes. The experimental results confirm the assumption that the gold nanoparticles adsorb the impurities' ions in FLC which leads to the decrease in the conductivity of the FLC layer. [ABSTRACT FROM AUTHOR]

Two experimental methods to estimate the electrochemically active surface area (EASA) of microelectrodes are investigated. One method is based on electrocapacitive measurements and depends significantly on the surface roughness as well as on other parameters. The other method is based on faradaic current measurements and depends on the geometric surface area. The experimental results are supplemented with numerical modeling of electrodes with different surface roughness. A systematic study reveals a strong influence of the scale and arrangement of the surface roughness, the measurement potential and the electrolyte concentration on the EASA of microelectrodes estimated from the electrocapacitive measurements. The results show that electrocapacitive measurements should not be used to estimate the faradaic EASA of microelectrodes with a non‐negligible surface roughness. [ABSTRACT FROM AUTHOR]

For problem that resonance point is difficult to determined which lead to measuring error of capacitive current when arc suppression coil with three phases and five columns in coal mine power grid is tuned by use of resonance method, an improved tuning method was proposed. Admittance triangle composed by fixed side of edge-to-ground conductance and variable sides of edge-to-ground susceptance and admittance according to characteristics of damping ratio unchanged and out-of-resonance degree changed in tuning process. Capacitance current is calculated according to change of admittance angle. The simulation and experimental results show that the improved tuning method has higher measuring accuracy than the resonance method, and measuring error decreases with increase of damping ratio.

The arc suppression coil determines whether it can effectively extinguish the arc when it is grounded in the neutral non-effective grounding system. An artificial grounding test is an importantway to verify its performance. In this study, 13 substations with the 10 kV system in the Ningxia areawere selected and considered. Based on the artificial single-phase grounding test, the residual current, the compensation current and the off-resonance degree were measured in the arc suppression coil, and the performance of the arc suppression coil in the 10 kV system was verified. The experimental results show that the error of arc suppression coil automatic measurement is large, the off-resonance degree is large, the resistive component in the compensation current is excessive, the harmonic component exists in the compensating current and capacitive current. To solve these problems, this paper puts forward the corresponding countermeasures for reference. [ABSTRACT FROM AUTHOR]

This paper presents current flow in cable screens and a cable screen earthing system. Moreover, the paper presents the methodology for the detection of problems in cable screens, such as open phase in a cable screen and high contact resistance of a cable screen in a cable joint. The is based on cable screen current measurements and allows for localization of the erroneous connection–high contact resistance or open phase. The phenomenon is simulated in PowerFactory Software. Moreover, exemplary cable screen current measurements are presented.

All of the technical devices that are powered by the frequency converter, apart from their great advantages, also bring considerable pitfalls and risks. When designing a machinery, it is necessary to consider the negative effects of characteristics of the frequency converter on the rotating parts, especially on the bearings of motors, gearboxes, gears, seals, etc. These devices and their parts are usually exposed to the effects of capacitive and shaft currents that have a considerable impact on the reliability of machines and equipment. This article focuses on the reasons for the use of insulated bearing (or insulated coupling) for asynchronous motors and on the influence of the measures taken to eliminate the adverse effects on the rotating parts. The following is an example of the use of technical diagnostics to determine the condition of some parts of the machinery, the example is evaluated, conclusions are drawn and analysed. [ABSTRACT FROM AUTHOR]

In this work it was demonstrated for the first time that Independent Components Analysis non-deterministic multivariate strategy enables estimation of the Faradic and double layer charging current components in differential pulse and anodic stripping voltammetry. The signals separation can be realized based on the different shapes of the capacitive and Faradaic current functions. The set of calibration voltammograms measured with the 1 kHz sampling frequency is the sufficient data to retrieve signals compatible with the theoretical shapes, with r 2 greater than 0.987 for Faradaic component and greater than 0.994 for capacitive component. In the effect, DP voltammograms of Pb(II) and Cd(II) recorded on silver annular band electrode were constructed using only Faradaic component. Quantitative analysis was performed and calibration models were calculated by different waiting time and sampling time, what demonstrated the possibility of significant improvement of sensitivity in considered experiments. [ABSTRACT FROM AUTHOR]

A new type of multipole columnar plasma reactor was proposed to reduce the capacitive current of dielectric barrier discharge. The discharge current and Lissajous diagram of multi-electrode columnar plasma reactor under different applied voltages were measured. The peak discharge current of the newly designed plasma reactor is reduced by 32.18%, from 1.274 A of the traditional device to 0.892 A. In addition, it is found that the micro-discharge is almost three times that of the conventional apparatus, indicating that more discharge channels are generated (from 46 to 113). With the increase of applied voltage, the equivalent capacitance and transferred charge of the multi-electrode plasma reactor increase approximately linearly with the rise in the number of discharge stages, which is mainly related to the distribution and region of the discharge plasma. In addition, the discharge characteristics of different electrode materials at the same applied voltage are compared, and it is found that the metallic activity of the electrode material causes microscopic changes in the discharge characteristics at high and low voltages. The results show that the performance of discharge plasma can be improved by optimizing electrode structure and materials. • The multi-electrode structure DBD reduces the discharge capacitance current. • Edge effect produces locally enhanced corona discharge. • Variation of equivalent capacitance between electrodes caused by charge transfer. • Different metal materials cause variation of discharge characteristics. [ABSTRACT FROM AUTHOR]

A new current decomposition method based on multiple linear regression is presented. The time-domain equations of every current component on the applied voltage are deduced based on an improved equivalent model of the metal–oxide surge arrester (MOA). The capacitive current compensation method and the proposed method are used to decompose the total leakage current and to study the influence of the nonlinearity of MOA model, third harmonic voltage, and white noise on the decomposition accuracy. The simulation results show that the proposed method can exactly decompose the resistive current and the capacitive current if the applied voltage and the total leakage current are noiseless. The proposed method is more accurate than the capacitive current compensation method. The total leakage current of an MOA varistor is measured and is then decomposed by both methods. The experimental results verify the effectiveness of the proposed method. [ABSTRACT FROM PUBLISHER]

The paper analyzed the distribution of capacitive currents in the winding of measuring high-voltage autotransformer at its operating frequency 50 (60) Hz. It is revealed that idling high-voltage autotransformer at significant nominal dividing coefficient these currents can acquire essential values against the current idling, which can affect the accuracy of large-scale conversion of high-voltage measuring autotransformers. The paper presents an approach to account values of interlayer capacitive currents in the windings of high-voltage autotransformers to clarify the distribution of voltage on their low-voltage (output) winding parts. It is shown that the distribution of capacitive currents significantly different to the first, last and middle layers of windings that must be considered when designing the windings of high-voltage autotransformers and calculate the number of turns in the respective high-voltage and low-voltage parts of windings. This analysis is particularly important for the development of standard measurement tools using high-voltage autotransformer scale transformation. [ABSTRACT FROM AUTHOR]

One of the key aims of electroanalytical methods development is the increase in sensitivity of measurements. This communication reports about a new amperometric technique called “interrupted amperometry” that is based on periodic interruption of the measuring electrical circuit. The main feature of this method is that capacitive current is analytically useful as well as faradaic current. This enables a dramatically higher sensitivity compared to the conventional amperometry. Theoretical consideration of the proposed method as well as the design of the home-made instrumentation is presented. Iron (III) was chosen as a model analyte in this preliminary study in order to demonstrate analytical possibilities of interrupted amperometry. The theoretical limit of detection of iron (III) at a carbon rotating disk electrode was found to be 3 nM. The calibration curve is linear in the whole investigated concentration range from 0.02 to 0.38 μM and gave a value of 1.22 μA μM −1 for the sensitivity. These results were compared with the values obtained in conventional direct-current amperometry mode other conditions being the same: 0.2 μM and 0.81 nA μM −1 for the limit of detection and sensitivity, respectively. The proposed technique can be useful for titration, flow injection analysis, HPLC, amperometric sensors, potentiostatic coulometry and for amperometric measurements with ultramicroelectrodes. [ABSTRACT FROM AUTHOR]

The paper aims to conduct a case study on the influence of the supply voltage variation on the parameters of electric power cables of low voltage consumers . The argument which was the basis for the study, was the fact that the voltage variation is a parameter of quality of electricity supplied by the network operator and respecting the limits of its variation is regulated both by performance standards , and by the electricity supply contract between electricity suppliers and consumers, consumption per seat basis. [ABSTRACT FROM AUTHOR]

Using an in situ electrical method and the multi-anvil apparatus, we determined the melting curve of sodium chloride (NaC1) up to ~20 GPa, with an estimated uncertainty of ±40 K. Our results agree well with the existing data up to 6.5 GPa. At higher pressures, the melting temperatures from this study are as much as 200 K higher than those from an experimental study using the diamond-anvil cell (DAC), and are up to 500 K lower than those from theoretical studies using molecular dynamics (MD). The discrepancies may originate from surface melting in the DAC measurements, which underestimate the melting temperature, and from superheating in MD calculations, which over-predict the melting temperature. Fitting our results to the Simon equation yield (T/T0)4.5 = (P - P0)/0.6 + 1, where T and T0 are the melting temperatures at P and P0, respectively, with T0 = 1073.6 K, T in K and P in GPa. The Simon equation fits the experimental data within uncertainties and therefore can be used to interpolate the melting curve. Using the equation of state (EoS) of NaCl at 300 K, the results are fitted to the Kraut-Kennedy equation in the form of T/T0 = (V0 - V)/V0·4.37 + 1, where T (in K) and T0 (= 1073.6 K) are the melting temperatures at V and V0 (at 0.0001 GPa), respectively. At pressures above 14 GPa, the experimental data deviate from the Kraut-Kennedy equation fit toward lower temperatures, probably because the volume dependence of the Grüneisen parameter was ignored in the equation. The Gilvarry-Lindemann equation Tm ~ 1.689·f2·Θ02·(V0/V)2(γ-1/3) provides a satisfactory fit to the melting curve of NaCl between 0 and 19 GPa if the exponent q in the volume dependence of the Grüneisen parameter γ = γ0·(V/V0)q is allowed to deviate from one. Given that the melting curve of NaCl up to 6.5 GPa is well established, monitoring the melting of NaCl offers an efficient alternative for pressure calibration of large-volume high-pressure apparatus for Earth science applications. [ABSTRACT FROM AUTHOR]

In order to the problems in anti-disturbance performance and inverter output voltage waveform quality for dual-loop control, this paper establishes the model of single - phase full-bridge-tied inverter, proposes the control strategy with load current feedforward setting on the basis of the original inverter dual-loop control, and simulates the strategy by MATLAB. The simulation result shows that the stability of the control system enhances apparently after bringing in load current feedforward setting, which improves anti-disturbance performance and inverter output voltage waveform quality. [ABSTRACT FROM AUTHOR]

In this study, a novel scheme is proposed for pilot protection of transmission line based on the fault component integrated power (FCIP). An appropriate definition is proposed for FCIP. The proposed scheme is able to quickly discriminate the normal condition, internal fault and external fault situations, even in severe operating and emergency conditions. This FCIP‐based scheme is not affected by the line charging capacitive and, therefore it does not need to be compensated for the capacitive current. Hence, this novel pilot protection scheme, based on FCIP, can be used for long distance high‐voltage transmission lines. The faulty phase/phases can also be detected by the proposed scheme. Moreover, compared with a newly‐introduced protective scheme which is based on the fault component integrated impedance, the proposed FCIP‐based scheme has faster operation speed. The efficiency of the proposed protective scheme is evaluated and approved over extensive simulation studies. [ABSTRACT FROM AUTHOR]

Copyright of e & i Elektrotechnik und Informationstechnik is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the results of computer simulation of the current flow through weakly conducting liquids at linearly-varying voltage. The simulation is carried out on the basis of a complete set of Electrohydrodynamic (EHD) equations. Two cases are considered: when a charge is formed in the bulk due to impurity molecule dissociation and when it is formed on the electrode surface due to the charge injection. The increase of the dissociation rate under the influence of an electric field is taken into account. The corresponding dynamic current-voltage characteristics are calculated and their specific features are revealed for every model of charge formation. It is shown that the hysteresis of the current-voltage characteristic is caused by the hysteresis of the electric field strength in the near-electrode area. The qualitative comparison of the simulation data and the experimental ones is carried out. [ABSTRACT FROM AUTHOR]