These load changes affect the arc characteristics, causing fluctuations of current. The current fluctuations cause variations in reactive power, which cause a momentary voltage drop or flicker, both at the supply bus and at nearby buses in the interconnected system. The arc currents are more uniform during the refining period and result in less impact on the power quality of the system. Arc furnaces also create harmonic load currents and asynchronous spectral components.
Harmonics represent an important power quality issue, because they may cause undesirable operating conditions.
According to IEEE standard , the power quality is "the concept of powering and grounding sensitive electronic equipment in manner that is suitable to the operation of that equipment and compatible with the premise wiring system and the other connected equipment. There are kinds of classifications power quality issues. IEC standard use the frequency range of the event for the classification of the power quality. As per IEEE classification, there are three different types of short duration events namely instantaneous, momentary and temporary.
Further each category is divided into interruption, sag and swell. Voltage sag b. Voltage swell c. Momentary interruptions d. Transients e. Voltage unbalance f. Harmonics g. Flickers g.
Voltage fluctuation VII. Lavers et al  describes the detail performance including the harmonic analysis by using a method of data acquisition and analysis of an electric arc furnace. The author in his paper presents the two arc furnaces supplied by 33 kV supply by individual 65 MVA on load tap changer furnace transformer. The results are obtained by the furnace during the operation the furnace current harmonics were found to be to the order of one to five percent with second, third and fifth dominating.
The harmonic components were found negligible during pellet operation. Aurelio Garria-Cerrada et al  has compared the performance of TCR based and VSI based flicker compensation experimentally from the arc furnace installation. An electrical arc furnace is a stochastic non linear load . The author has proposed a model for an arc furnace by assuming that whenever there is current, the voltage drop is constant for fixed for fixed arc length. Such a stochastic model of electric arc furnace generates harmonic voltage in the distribution system. The voltage fluctuation of the fundamental component is the origin of flickers  in the system.
Flicker is due to the variations of the voltage as low as 0. The author used the data collected from the primary of the furnace transformer. Zhang et al  has explained how to measure the flickers produced by the arc furnace and its compensation. The performance of SVG was investigated for flicker compensation due to its fast response. SVG has been taken into the circuit to replace the conventional SVC Static Voltage Compensator due to its long response time, costly and large in size.
It was developed in late s for the compensation of large fluctuating industrial loads. The SVC can operate selectively connecting passive element with the power line but the SVG is a controlled ac voltage connected to the power line by a reactor. Harmonic compensation is better for SVG with the same capacity.
Chena et al  has explained the voltage fluctuation problem and proposed the mitigation of such voltage fluctuation by using SVC. The SVC consists of passive harmonic filter to provide the required amount of reactive power and one TCR for susceptance control.
Full text of "Power Quality Issues of Electric Arc Furnace and their Mitigations -A Review"
The voltage fluctuation is a big problem during the steel production and for the other industrial customer. The voltage fluctuation problems are generated in the industrial power system containing electric arc furnace due to transient current absorbed by the arc furnace during its early stages of operation.
To mitigate the voltage fluctuation, the author proposed the installation of SVC. It is found that that the voltage fluctuation is reduced by 0.
Omer Ozgun et al  has explained that the voltage flickers and harmonic load current are the examples of adverse effects produced by the arc furnace while in operation especially in early stages. The impact of such highly non linear time varying load needs to be investigated. The author proposed to present an arc furnace model in two stages: Dynamic and multivalve voltage - current characteristics of the electrical arc in the first part and generation of low frequency chaotic signal by the simulation of Chua circuit to obtain the voltage fluctuation in the latter part.
The differential equation which represents the dynamics of arc model is based on principle of energy conversion. The following differential equation is given as .
The second part of the electric arc furnace is to generate the chaotic signal of the arc voltage. The block 5 executes the online statistical analysis of the statistical analysis of the instantaneous flicker level. In this block, both the short term and long term flicker severity level indices are calculated and the results are displayed.
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The output of this block is divided into 64 subclasses according to the instantaneous flicker level. The short term flicker P st can be calculated by using the following expression Where k i is the weighing coefficient and Pi the flicker level these Pj are taken from cumulative distribution curve. At least five points are normally taken while evaluating short term flicker severity. The short term flicker Pst is found to be 1. Pamiani et al  has presented the benefits of the dynamic reactive shunt compensation by SVC in steel factory. Higher efficiency is the prime importance for the steel industries and to improve the efficiency of the system.
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Page 25 www. The author investigated the simulated result of the SVC which eliminates the supply reactance. Additional active power is delivered to the arc furnace when the SVC is in the circuit. Voltage variation is also observed to be low as compared to without SVC in the circuit. The author also proposed the oversized transformer or use of more transformers which reduces the short circuit impedance between the EAF and network. In this condition the SVC at the arc furnace is the solution.
In this condition, the maximum active power transferred is increased but the voltage variation from no load to full load remains the same. The supply system is assumed to be balanced, the furnace transformer assumed to be an ideal transformer with ratio tp: 1 with zero phase shift and the arc furnace load is considered to be operated in balanced condition.
According to the author the model is considered to be flexible and accurate. The difference between the proposed model and the existing model is that the control system is included in the model proposed which has been shown in the figure 5. The arc is represented by a non linear current controller resistor. The pattern of the arc generated is determined by the arc length which is controlled by the controller.
The interaction among three components namely supply system, the arc furnace load and the control system constitutes the adaptive arc furnace model. The figure 6 The arc melting process can be divided into three periods. In the first period the arc begins to reignite from extinction, the arc is established and in the thirds period the arc begins to extinguish.
The arc furnace control basically monitors the electrical and thermal parameters to make the arc furnace operation safe and efficient.
The proposed controller is different from the actual controller. Some assumptions are made for the proposed controller.
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The author has presented only fifth, seventh and eleventh component of harmonics are produced. The current harmonics shows the different characterizations in melting and refining stages.
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