scholarly journals Electric Arc Furnaces as a Cause of Current and Voltage Asymmetry

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5058
Author(s):  
Zbigniew Olczykowski
Keyword(s):  
Short Circuit ◽  
Electric Arc ◽  
Arc Furnace ◽  
High Current ◽  
Operating Characteristics ◽  
Electric Arc Furnaces ◽  
Arc Furnaces ◽  
Three Phase ◽  
Quality Analyzer ◽  
Theoretical Considerations

In the case of three-phase arc furnaces, two types of asymmetry can be distinguished: constructional and operational. The structural asymmetry is related to the construction of high-current circuits supplying the arc furnace. The knowledge of the parameters of the high-current circuit allows to determine the operating characteristics of the arc device. The author proposed a method for calculating the real values of the resistance and reactance of the high-current circuit. For this purpose, tests were made to short-circuit the electrodes with the charge. During the short-circuit, with the use of a power quality analyzer, measurements of electrical indicators were carried out, which allow to determine the parameters of the high-current circuit. A new method for determining voltage operational unbalance is also presented in this paper. The theoretical considerations presented in the article were verified in industrial conditions.

Improving the efficiency of electric arc furnaces through improved control algorithms for electrical modes

2020 ◽  
pp. 10-16
Author(s):  
A. A. Nikolaev ◽  
◽  
G. P. Kornilov ◽  
P. G. Tulupov ◽  
G. V. Nikiforov ◽  
...  
Keyword(s):  
Short Circuit ◽  
Unit Cost ◽  
High Energy ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Control Algorithms ◽  
Separate Analysis ◽  
Arc Furnace ◽  
Electric Arc Furnaces ◽  
Arc Furnaces

The aim of this study is to increase the efficiency of electric arc furnace through the use of advanced control algorithms for electrical modes. It was established that despite the common structure of the electric control system, as well as the approach to diagnosing the stage of the technological process, the criteria for switching from one combination of the furnace transformer tap and operating curve to another for electric arc furnaces and ladle furnaces are different. So, for EAF it is advisable to use a system in which a separate analysis of the signals of the relative effective value of the total even and odd harmonics of electric arc current (voltage) should be applied. It’s important to note that at the initial stage of melting it’s preferable to use even harmonics, and at the final stage of melting - odd harmonics. In it’s turn, during melting in LF, the argon blow mode and the slag mode have a significant role. Intensive blowing modes lead to the appearance of a metal mirror with the occurrence of bursts that occure short-circuit of the electric arc and lead to not optimal electric mode. According to the results of the analysis, a number of recommendations have been formulated that can have practical application in modernizing of modern control systems, aimed at optimizing production energy costs and reducing the unit cost of the final product of the metallurgical cycle. Moreover, the experience of implementing the described ides shows (for shaft-type electric arc furnace with capacity 125 ton, 85 MVA and ladle furnace 25 MVA) that the economic effect is 2.5% in terms of saving electric energy and 2% in terms of saving the consumption of electrodes. It’s a significant indicator taking into account the high energy intensity of modern electric steelmaking shops. This work was supported by the Ministry of Science and Higher Education of the Russian Federation (project No. FZRU-2020-0011).

scholarly journals Research on Transient Power Quality of Large-capacity Electric Arc Furnace

2021 ◽  
Author(s):  
Liu Yang ◽  
Qinyue Tan ◽  
Di Xiong ◽  
Zhengguang Liu
Keyword(s):  
Power Quality ◽  
Reactive Power ◽  
Short Circuit ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Normal Operation ◽  
Arc Furnace ◽  
Three Phase ◽  
Transient Power Quality

The overrun of transient power quality index caused by the large-capacity electric arc furnace (EAF) has become a prominent problem affecting the safe and stable operation of the power system. (1) In this paper, the relationship between arc furnace volt-age and current is derived based on the different stages of arc combustion, and the random variation of chaotic phenomenon of the arc voltage are simulated. Established an EAF model suitable for the study of transient power quality problems. (2) Take 50t AC EAF as an example to analyze the reactive power impact and the influence on the point of common coupling (PCC) voltage caused by the three-phase short circuit of the electrode. The results show that the experimental results are consistent with the theoretical analysis, verifying the correctness and effectiveness of the model. (3) When the three-phase short-circuit occurs, the reactive power impact is nearly 6 times that of normal operation, the short-circuit current is 2.66 times that of normal operation, and the effective value of the PCC voltage has dropped by 40.37%, which provides a theoretical basis for real-time compensation of impulsive reactive power and improvement of the transient power quality of the EAF.

Influence of the geometry arc furnace steel taphole on production parameters of the casting and rolling complex of JSC VMZ

2021 ◽  
pp. 11-16
Author(s):  
V. N. Lavrov ◽  
◽  
S. A. Botnikov ◽  
A. V. Kosonogov ◽  
S. A. Somov ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Electric Arc ◽  
Arc Furnace ◽  
Electric Arc Furnaces ◽  
Production Parameters ◽  
Arc Furnaces ◽  
Casting And Rolling Complex ◽  
Liquid Residue ◽  
Furnace Steel ◽  
Furnace Slag

Currently the majority of modern electric arc furnaces (EAF) are equipped with bottom eccentric taphole system. This design allows to tap metal from EAF to ladle with the minimum amount of furnace slag, leaving a part of the liquid metal in EAF for subsequent heats (“liquid start”), if this residue is sufficient. In this case, taphole has several disadvantages: - it is not completely excluded that the oxidized furnace slag enters the ladle, especially with a low level of liquid residue in the EAF, the mass of captured slag in the ladle increases; - tapping time is unstable during taphole system campaign and depends on the wear of its constituent refractories; - periodically required to replace taphole refractories, thus it’s necessary to stop EAF. Under the conditions of the casting and rolling complex JSC “Vyksa Steel Works” work has carried out to change shape EAF’s taphole system, which made it possible to reduce the effect of these disadvantages on the efficiency of the EAF.

scholarly journals New Arc Stability Index for Industrial AC Three-Phase Electric Arc Furnaces Based on Acoustic Signals

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6840
Author(s):  
Juan Guerra-Serrano ◽  
Angel Sánchez-Roca ◽  
Guillermo González-Yero ◽  
Mario C. Sánchez-Orozco ◽  
Mercedes Pérez de la Parte ◽  
...  
Keyword(s):  
Harmonic Distortion ◽  
Stability Index ◽  
Melting Process ◽  
Acoustic Signals ◽  
Electric Arc ◽  
Electrical Networks ◽  
Electric Arc Furnaces ◽  
Arc Furnaces ◽  
Starting Point ◽  
Three Phase

This research proposes a new index to evaluate the stability of the melting process, in three-phase electric arc furnaces (EAFs), based on the acoustic signals generated during the different stages of the casting. The proposed stability index is obtained by characterizing the time and frequency domain of the acoustic signals. During EAF monitoring, acoustic signals were acquired using a microphone coupled to an NI USB-9234 acquisition system. To validate the results, the voltage and current signals were measured with the aid of a Circutor AR6 power analyzer for three-phase electrical networks. The results showed that the acoustic signal energy in the frequency range of 1 to 12 kHz can be used as an indicator of the process stability in the EAF. Finally, the validity of the proposed stability index is evaluated from the process characterization using the harmonic distortion analysis methods and the dynamic U-I characteristics of the arc voltage and current signals. The results obtained demonstrated the effectiveness of the proposal and constitute a starting point for advances in the automatic control of the process in the EAF, from the acoustic signals.

scholarly journals Analysis of Transient Voltage Problem Caused by Electric Arc Furnace

2021 ◽  
Author(s):  
Liu Yang ◽  
Qinyue Tan ◽  
Di Xiong
Keyword(s):  
Power Quality ◽  
Short Circuit ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Normal Operation ◽  
Hyperbolic Function ◽  
Arc Furnace ◽  
Voltage Fluctuation ◽  
Three Phase ◽  
Transient Voltage

Three-phase AC electric arc furnace (EAF) is a typical non-linear load, causing many power quality problems. Most of the researches on the voltage problems of EAF mainly focus on the voltage fluctuation, and less on the transient voltage problems caused by EAF short circuit and open circuit. In this paper, the relationship between voltage and current of EAF is obtained by combining hyperbolic function and exponential function, then the white noise and chaotic circuit are added to establish the EAF model which is suitable for the study of voltage fluctuation and transient voltage. This paper analyzes the causes of the transient voltage problem of the EAF, calculates the short-circuit current, reactive impact and the influence on voltage at the point of common coupling (PCC) in the three-phase short-circuit of the EAF, and compares the calculation results with the simulation results to prove the accuracy of this model. The results show that the reactive impact of three-phase short circuit is about twice as much as that of normal operation of EAF, resulting in about 30% voltage sag at the PCC, which is very unfavorable to the power grid. This paper provides reference for transient power quality evaluation and dynamic reactive power compensation of EAF.

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