Arc Model Research Articles

Short-circuit Current Reduction in Auxiliary Network of Traction Substations

The article analyzes short circuit current reduction due to three main factors: electrical arc, cable heating and contact and coil resistance in auxiliary network of traction substations. The research was made using ETAP software module Unbalance Short Circuit, where mathematical model of dynamic arc, as it is described by Russian and abroad scientists, iterative cable heating as it is described in Russian and European standards and contact resistance were implemented. Mathematical model includes power grid, auxiliary transformer, circuit breakers, current transformer, and cable. Cable size varies to show influence of each above-mentioned factors. Calculations were made using phase domain method and all the parts of auxiliary network were considered. The results show up to 60 percent decrease in three-phase short circuit current considering three factors together. It influences the ability to trip short circuit current by backup protections, fault-clearing time, cable sizing and the power supply quality. Neglect of one or more factors may, in some cases, mean insensitivity of the protection and the inability to trip the short circuit current in time.

Study on the Calculation of 35 kV Parallel Gap Arcing Time Considering the Influence of Wind Load

Wind load is the important factor influencing arc-extinguishing of arc. Establishing arc chain motion model of 35 kV parallel gap under wind load condition, the electromagnetic force, air resistance and wind force of a single arc element are analyzed by using the chain arc model. The arc motion parameters were solved. The arc anti-resistance and arc resistance are calculated; the criterion of arc extinguishing is defined; the arc burning time is calculated, and the arc burning time is obtained. Through the calculation of arc ignition time, it can be seen that the magnitude of wind load affects the arc free time. When the wind load increases, the arc ignition time will be shortened.

직류 차단기에 대한 Black-box 아크 모델 적용성 평가 및 아크 특성 매개 변수 비교 분석

Analyzing the arc interruption phenomena of circuit breakers, physical arc model is generally used, but its analysis and applications is complex because it requires understanding a lot of physical parameters such as thermodynamics and mathematical equations which occur during arc interruption process. But the black box model which simulate the dynamic arc behaviour and its interaction with network could be conveniently used to extract essential parameters to determine the performance of the circuit breaker. Black box arc model could represent the non-linear characteristics of the arc using differential equations based on the conductivity of the arc. In order to develop reliable DC circuit breaker which don’t have a natural current zero point, a transient analysis of the non-linear arc characteristics occurring during interruption is needed. In previous studies, black box arc models have been used to analyze AC arc characteristics, and there are few study applying it to DC circuit breakers. This paper simulates the applicability evaluation for DC circuit breakers using KEMA and Habedank black box arc models based on the actual DC circuit breaker test data sheet. Parameters of the black box arc model were determined by performing Parameter Sweep for the main factors, such as interrupting time, arc voltage, and arc time constant. As a result, the applicability of the black box arc model to the DC circuit breaker was verified by predicting the DC arc behavior, and more suitable model for the DC circuit breaker was suggested by comparing the DC arc waveforms.

Interrupter Size Effect of High‐Voltage Gas Circuit Breaker on Thermal Interruption Performance and Current Zero Properties

Small model interrupters are convenient to investigate interrupting performance of high‐voltage gas circuit breakers in terms of efficiency. However, the equivalence of interruption phenomena of small model interrupters (e.g., interrupting performance, interruption criteria, and geometric sensitivity) to product‐scale interrupters has not been clarified. Interrupting tests with small and large model interrupters were carried out with the dimensions of the interrupter as parameters to clarify the effects of modified interrupter dimensions on blast pressure and interrupting performance. Arc voltage and arc conductance were measured to acquire detailed electrical behavior in the thermal interrupting phase. In the results, small model interrupters showed the same performance trends as geometrically modified large model interrupters. By introducing an interrupter size factor, the boundary of the extinction peak of the arc voltage and arc conductance at 200 ns before current zero that distinguishes the success and failure of interruption for both small and large models agreed well. Moreover, the arc parameters determined by Cassie and Mayr arc models were analyzed with consideration to interrupter size factor. In conclusion, the interrupter size factor was validated from the point of arc phenomena and an equivalence of small model to product‐scale interrupter was confirmed. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Data‐enhanced machine recognition model of DC serial arc in electric vehicle power system

Electric vehicle (EV) power system is the key to the development of EVs. If direct current (DC) arc occurs in the power system, it is difficult to extinguish at zero point. The arc fault will release a huge amount of energy and continuous sparking, which may cause spontaneous combustion or even explosion. In this study, an arc detection algorithm based on the classification of windowed Fourier transform and support vector machine (SVM) model is proposed for DC serial arc detection of EV power system. In order to optimise the arc detection algorithm, the authors use the pre-detection algorithm, which can effectively reduce the false detection rate of DC arc fault and ensure the reliability of detection algorithm. In addition, they propose an arc fault data enhancement model, which can generate arc fault current data. Finally, the experimental results show that the arc detection algorithm has a high accuracy and a false detection rate of 0%. After data enhancement, it has generalisation of the SVM classification model under the condition of high power experiment.

The Effect of the Selection of a Function Approximating Static Characteristics on the Modelling of Electric Arc

The article presents selected tapering functions useful when creating hybrid models and functions approximating static current-voltage characteristics of arc. The research work involved the formation and verification of families of static current-voltage characteristics with defined values of voltage ignition and the extension of approximating possibilities of the formulas through the use of tapering functions. The effective use of various functions approximating static characteristics in the modelling of dynamic states in the circuit with electric arc was verified through simulation.

Black-box 아크 모델의 비선형 특성을 활용한 고체 절연물 내 보이드에 의한 부분방전 해석모델 개발

Black-box 아크 모델의 비선형 특성을 활용한 고체 절연물 내 보이드에 의한 부분방전 해석모델 개발

Early Neoarchean oceanic crust in the North China Craton: Evidence from geology, geochemistry and geochronology of greenstone belts in western Shandong

Western Shandong is the only area in the North China Craton where abundant supracrustal rocks of the early and late Neoarchean are developed. This study presents an integrated geological investigations, whole-rock geochemistry and SHRIMP UPb zircon dating investigation of the supracrustal rocks at Yanlingguang, one of the most typical areas of Neoarchean supracrustal rocks in western Shandong. The original Yanlingguan ‘formation’ is now subdivided into three belts: the Northeastern, Central and Southwestern belts, which are all in tectonic contact. The Northeastern and Southwestern belts are mainly composed of meta-komatiitic and basaltic rocks. Four granitic dykes intruding these belts have magmatic zircon ages of 2731–2530 Ma, supporting the conclusion that the supracrustal rocks were formed in the early Neoarchean. Meta-basalt with pillow structures has been identified in several locations, with the largest being ~35 m in thickness. The meta-komatiitic rocks are Al-undepleted komatiites and have ∑REE and (La/Yb)n of 2.30–26.21 ppm and 0.29–2.35, respectively, whereas the meta-basaltic rocks have ∑REE and (La/Yb)n of 16.45–53.26 ppm and 0.67–1.78, respectively, and εNd(t) values of 3.36–4.76, being similar to N-MORB. Eleven samples of meta-sedimentary rocks (including meta-sandstones-siltstones and meta-conglomerates) from the Central Belt have zircon UPb ages extending from 2760 to 2520 Ma, providing evidence for the first time that they were deposited during the late Neoarchean, rather than the early Neoarchean as previously thought. The meta-sandstones-siltstones show large variations in major element contents, but have low ∑REE (49.17–102.30 ppm) and (La/Yb)n (1.53–7.00) ratios, with negligible to weakly negative or positive Eu anomalies (Eu/Eu* = 0.60–1.17), and record εNd(t) values of 0.96–3.21. Combined with regional geological investigations, we conclude that the early Neoarchean supracrustal rocks were formed in an oceanic environment. It is also suggested that the sandstones-siltstones of the late Neoarchean were derived from the early Neoarchean basement, and that the conglomerates were derived from two separate source regions; one of early, and the other of late Neoarchean age. The identification of basal conglomerates is consistent with the arc model established in early studies. We suggest that the criteria employed in this study can be used for determining whether or not an Archean greenstone belt is of oceanic affinity.

A Modified Mayr-Pentegov Model of the Electric Arc with Dynamically Variable Parameters

A Modified Mayr-Pentegov Model of the Electric Arc with Dynamically Variable Parameters

A Convenient Unified Model to Display the Mobile Keyhole-Mode Arc Welding Process

Keyhole-mode plasma arc welding (PAW) has a good prospect in the manufacturing industry. Unified models of plasma arc and workpiece help to reveal the physical mechanism in PAW for a better application. Previous unified models either deal with a constant keyhole situation or take too much computational time to display the dynamic keyhole process with a two-phase flow method. In view of the convenience for industrial application as well as good accuracy, a convenient unified model was developed to describe the mobile keyhole-mode PAW. With a simplified technique, the multiphase heat and force effect between plasma arc and workpiece was turned into a single-phase problem at each individual domain. Thus, it takes less computational time than previous unified models. The temperature field and weld pool during the mobile keyhole-mode PAW process were revealed, the arc flow and pool flow were displayed and the electric potential was predicted. The experiment was conducted on a stainless-steel plate, and the weld pool image and the measured arc pressure agree well with the calculated result. The calculated electric potential drop also coincides with the experiment. The model provides a convenient and accurate method to display the mobile keyhole-mode arc welding process.

Simulation of a single-phase arc grounding fault on a 220-kV cable transmission system

Cable tunnel fires are mainly caused by single-phase arc grounding faults. The massive energy generated by arc can threaten the safety of the densely laid cable tunnels. In this study, a digital arc fault model with a 220-kV cable transmission system was established on Power Systems Computer Aided Design(PSCAD). The arc model was improved because the parameters were acquired from the experimental results. The arc fault can be divided into two stages: a primary arc at the initiation of the fault and a secondary arc after the tripping of the circuit breakers. The primary arc contains few nonlinear components because of the large arc currents. The secondary arc voltages exhibit nonlinear characteristics because of arc elongation. The secondary arc power continues to increase, however, its amplitude is considerably smaller than the primary arc. The lifetime of the primary arc is dependent on the action of the relaying protection system. Further, some limits based on the energy balance theory were introduced to obtain the extinction time of the secondary arc. In addition, the total energy generated by the arc fault in the 220-kV cable transmission system will eventually become 4891 kJ. This digital arc fault model will significantly contribute to future research with respect to the mechanism of cable tunnel fires.

Geospatial analysis of chilghoza forest in Sulaiman Mountainous Range

Pinus gerardiana (chilghoza) is a rare gymnosperm that grows in dry temperate conditions. It is also consider as precious specie because of its medicinal and economical value. Pakistan is a blessed country with chilghoza forests in Khyber Pakhtunkhwa (KPK), Balochistan, Kashmir and Gilgit-Baltistan. This study was carried out to monitor the chilghoza growing in the Sulaiman Mountainous Region of Sherani district Balochistan, in order to detect the health status and land cover changes of chilghoza from the year 1999 to 2019 by using the techniques of Geographical Information System and Remote Sensing. Supervised machine learning algorithm was employed to classify the seven land cover classes and calculate the area cover occupied by each class and also analyzed the shifting pattern of these classes. While Arc Model was built to check the health status. The results revealed that the area about 174 km2 was covered by thick chilghoza in the year 1999, but it decreased up to 84.9 km2 recorded in the year 2009, and increased again upto 127 km2 in the year 2019. On the other hand, sparse chilghoza occupied an area of 77.5 km2, 247.7 km2 and 139.9 km2 in the year 1999, 2009 and 2019, respectively. These results depicted the decrease in chilghoza cover during 1999–2009 year due to overexploitation and gradual increase in land cover of chilghoza after the year 2009 due to the conservation efforts carried by government and non-governmental organizations. Further conservation and protection are required for this specie because it is not only rare specie but also an excellent source for economic benefits on local, national and international scales.

Numerical Estimation of the Geometry and Temperature of An Alternating Current Steelmaking Electric Arc

A channel arc model (CAM) that predicts the temperature and the geometry of an electric arc from its voltage and impedance set‐points is presented. The core of the model is a nonlinear programming (NLP) formulation that minimizes the entropy production of a plasma column, the physical and electrical properties of which satisfy the Elenbaas–Heller equation and Ohm's law. The radiative properties of the plasma are approximated utilizing the net emission coefficient (NEC), and the NLP is solved using a global numerical solver. The effects of the voltage and impedance set‐points on the length of the electric arc are studied, and a linear formula that estimates the length of the arc in terms of its electrical set‐points is deducted. The length of various electric arcs is measured in a fully operative electric arc furnace (EAF), and the results are used to validate the proposed models. The errors in the predictions of the models are 0.5 and 0.4 cm. In comparison, the existing empirical and Bowman formulae estimate the length of the experimental arcs with errors of 2.1 and 2.6 cm. A simplified formula to estimate the temperature of an electric arc in terms of its electrical set‐points is also presented.

Unified modelling of low-current short-length arcs between copper electrodes

In this work, we present for the first time a unified model of a low-current short-length arc between copper electrodes. The model employs one-dimensional fluid description of the plasma in argon and copper vapour at atmospheric pressure and the heat transfer in the electrodes made of copper. The solution of the particle and energy conservation of electrons and heavy particles is coupled with the solution of the Poisson equation, from which the self-consistent electric field is obtained. The operation of the non-refractory cathode is based on thermo-field emission. Heat fluxes from the plasma to the electrodes are considered so that a phase change and evaporation from the cathode and a release of copper atoms into the plasma are taken into account. The influence of the copper atoms and ions on the plasma properties is analysed and discussed. The model’s predictions are compared with experimental data and a qualitative agreement is obtained besides the restrictions of the one-dimensional fluid model.

Multifield Coupled Dynamics of Power Supply Arc Based on Image 3D Reconstruction Mathematical Model

During the conversion process of the short-circuit arc to the submerged power supply arc, because the short-circuit arc diameter is much larger than the submerged power supply arc, the specific position of the submerged power supply arc cannot be determined, and the initial position of the submerged power supply arc has a certain randomness. The purpose of this paper is to try to use the binocular stereo vision method to reconstruct the submerged arc image in three dimensions, obtain the moving image of the arc, obtain more comprehensive information than the two-dimensional image, and multi-field coupling dynamics of the power supply arc. In this paper, the multi-field coupling effects of electromagnetic force, thermal buoyancy, wind load and air resistance of the submerged arc of the half-wavelength transmission line are considered comprehensively, and the chain arc model is incorporated into the force equation and motion model of the submerged arc. By deeply analyzing the formation and motion mechanism of the arc root, the arc root model of the submerged power arc is established, and the optimal selection method of the current element length is proposed. The physical simulation experiment of the half-wavelength submerged arc is carried out, and the simulation results are compared with the experimental results to verify the effectiveness of the simulation model. By comparing the trajectory and self-extinguishing time of different submerged currents, wind speeds and winds to the submerged power supply arc, the effects of wind load, thermal buoyancy and electromagnetic force on the arc are analyzed, which indicates that the built arc model can effectively account for the wind load. The influence of submarine power arc motion and self-extinguishing characteristics. The results show that the submarine power arc image is acquired by constructing a binocular stereo vision system, and the obtained submersible arc image is reconstructed three-dimensionally. The three-dimensional image of the arc is obtained and compared with the actual image. The result shows that the three-dimensional reconstruction The result is effective, and the exploration study provides a new method for further obtaining the multiple variations of the true arc length of the arc with the arcing time.

Magmatic gap associated with stepwise arc‐continent collision during the subduction of Banggong‐Nujiang Tethys Ocean: Evidence from Late Jurassic bimodal magmas

The magmatic suites in the southern margin of South Qiangtang Terrane (SQT) provide important clues to the process of northward subduction of the Banggong‐Nujiang Tethys Ocean (BNTO) and its geodynamic evolution. Previous studies identified a magmatic gap from Late Jurassic to Early Cretaceous (ca. 150–130 Ma) in the southern margin of SQT. Although the gap is generally correlated with the process related to BNTO subduction, the previous models on this remain equivocal. In this study, we investigated a suite of bimodal magmatic rocks newly recognized in the Rigenco area of SQT, including gabbros and granodiorites which were dated at 151.7 ± 3.8 Ma and 150.0 ± 2.0 Ma respectively. Based on geochemical and isotopic analyses, it is inferred that the gabbroic magmas were derived from a sub‐arc mantle source enriched by metasomatism of voluminous slab‐derived and crustal compositions, and that the granodiorites were derived from sub‐arc juvenile lower crust. Combining the petrogenesis of gabbros and granodiorites, it is proposed that the bimodal magmas were produced under a tectonic setting of general compression with local extension. A detailed evaluation of the tectonic setting of the magmatic bimodal suite suggests crustal thickening at ca. 150 Ma and that the BNTO involved multiple arcs and sub‐basins. A new model of arc‐SQT collision is proposed to account for the magmatic gap which commenced at ca. 150 Ma. The model of arc–continent collision in this case can well explain the present distribution and occurrence of magmatic rocks of late Jurassic age in the southern margin of the SQT, especially the magmatic gap. Our discovery of Late Jurassic bimodal rocks provides a critical evidence for step‐wise arc–continent collision during BNTO subduction, and contributes to the understanding of the magmatic gap in SQT and the evolution of BNTO.

On a model of the vacuum arc at a volatile cathode (Cd and Hg)

For volatile cathodes (e.g., Hg), the ratio of the work function and the latent heat of vaporization is such that vaporization cooling overwhelmingly exceeds ion heating at moderate cathode temperatures. This fact was an obstacle in cathode spot modeling for cathodes of such metals. Analysis of the emission process at higher temperatures revealed the effect of “phase transition” that takes place at some critical temperatures: 1360 K for mercury and 2040 K for cadmium. During a very sharp transition that occurs within a few degrees or less, there is a simultaneous rise of electron emission, the arrival of an intense ion flux at the cathode, and a reduction or even reverse of emission cooling (the Nottingham effect), which leads to a completely new cathode state. Heat flux to the cathode goes from being highly negative to highly positive. This makes it possible for the arc to burn. The characteristics of that new state are similar to that of a regular cathode spot of a vacuum arc. A scenario of cathode spot cycling with this new state is suggested.

Simulation Test Study on Combined Gap Structure of High-speed Railway Catenary

In order to deal with the lightning damage problem commonly existing in high-speed railway catenary, a combined multi-breakpoint arc-extinguishing and lightning protection gap device (CMALPGD) which can be applied to high-speed railway catenary is proposed in this paper. Based on the principle of gas production and arc quenching of the device, a three-dimensional dynamic (MHD) model of arc in the arc-extinguishing chamber is established. With the help of simulation software to simulate the changes of the temperature, conductivity and high-speed airflow velocity of the arc at the fracture of the arc-extinguishing chamber, it is known that the high-speed air flow generated by the arc-extinguishing device can quickly extinguish the arc and restrain the arc development, and the whole quenching time is about 2.5ms. At the same time, the arc-extinguishing test is carried out by setting up the test circuit under laboratory conditions, and it is found that the arc-extinguishing time of the device is about 3.0ms and the arc is not reignited for a period of time. The conclusions provide a scientific basis for the application of CMALPGD in high-speed railway catenary in the future.

Detailed electro‐dynamic model of an ultra‐fast disconnector including the failure mode

Ultra-fast disconnector (UFD) is a key component of hybrid DC circuit breakers and it is also studied as the main switch in some DC grid topologies. A UFD model suitable for DC grid studies and considering both normal operation and failure mode is presented. The dynamic motion of contacts is analysed in detail and it is concluded that Thomson coil inductances including parasitic parameters play an important role and it is recommended to use finite element modelling. The arcing mode of UFD is repressed using a variable resistance in series with an ideal switch. The variable resistance is calculated analytically based on the instantaneous position of contacts and the circuit conditions. Two different arc models are recommended: for the air-insulated UFD and SF6 UFD, and in each case, two operating regimes should be considered: high and low currents. The UFD model is verified for both normal operation and failure mode using measurements on a 5 kV laboratory UFD and the results show very good matching. The 320 kV SF6 UFD model is evaluated using limited reported results from manufacturers.

Neoarchean–Paleoproterozoic crustal growth and tectonic evolution of the Trans-North China Orogen, North China Craton: evidence from granite–greenstone successions in the Dengfeng Complex

Granite–greenstone successions and associated tonalite–trondhjemite–granodiorite (TTG) suites constitute dominant components of Precambrian cratons. Here, we present petrology, geochemistry, zircon U–Pb geochronology, and Lu–Hf isotopes on monzonite, granodiorite, granite, and amphibolite from the Dengfeng Complex in the southern part of the North China Craton (NCC). Zircon U–Pb data yield weighted mean 207Pb/206Pb ages of 2498 ± 6 Ma for monzonite, 2481 ± 16 Ma for granodiorite, and 2475 ± 21 Ma for granite. Lu–Hf isotope systematics show eHf(t) values ranging from 1.3 to 6.7 and crustal model ages ( $$T_{{{\text{DM}}}}^{{\text{C}}}$$ ) in the range of 2584–2934 Ma for the rocks. The monzonite, granodiorite, and granite show moderate total rare-earth element (REE) contents, enrichment in light REEs (LREE) and depletion in heavy REEs (HREE), negative Nb, Ta, and Ti anomalies, high Al2O3, Sr/Y, and (La/Yb)N ratios, with low Cr and Ni, indicating that the magma was possibly sourced from partial melting of the lower crust. The geochemical features of amphibolites are characterized by low SiO2, Na2O, K2O, Sr/Y, (La/Yb)N and high FeO, low total REEs values, limited LREE/HREE fractionation, and absence of obvious Ce anomaly, showing similarity to island arc magmatic rocks. Our results are consistent with the model of subduction and arc–continent collision in the Trans-North China Orogen during the Neoarchean to Paleoproterozoic.