Electric Arc Furnace Load Research Articles

Identification of Combined Power Quality Disturbances in the Presence of Distributed Generations using Variational Mode Decomposition and K-nearest Neighbors Classifier

Identification of combined power quality disturbances in the modern power systems by considering the development of different types of loads and distribution generations has become increasingly important. The novelty of this paper comes from the accurate and fast identification of the combined power quality disturbances in the presence of different distributed generations and loads such as photovoltaic cell, wind turbine with doubly fed induction generators, diesel engines, electric arc furnace, DC machine, 6-pulse and 12-pulse rectifier loads. In this paper, the features are extracted using variational mode decomposition, just from voltage waveforms. To reduce the redundant data, dimension of features vector, and time, the Relief-F method and correlation feature selection method are applied on the extracted features and these two methods are compared together. In this paper, the K-nearest neighbors classifier is used to classify the multiple power quality disturbances. To verify the effectiveness of the proposed method, different scenarios such as misfiring, variation of sun radiation and wind speed, entrance and exit of loads, capacitors and distributed generators, different fault at the grid in half-load to full-load were simulated. This method can be used as an added algorithm for smart metering in modern and smart power systems.

Comparison techniques using phase – loop locked (PLL) and synchronous references frame (SRF) controller to mitigate voltage flicker

Voltage flicker is one of the vital disruptions in electrical distribution power systems. An electric arc furnace is considering as one of the major causes of voltage flicker due to it an unbalanced, nonlinear and time-varying behaviours. Distribution Synchronous static compensator (D-STATCOM) has been shown to be a competent and dynamic device to compensate voltage flicker in power system. This paper presents a comparison between Phase-Loop Locked (PLL) Controller and Synchronous References Frame (SRF) Controller technique for 6-pulse D-STATCOM to compensate voltage flicker due to electric arc furnace load. To observe the effectiveness of the proposed technique, testing has been conducted on IEEE 13 distribution bus test system. The simulation results show the effectiveness of 6-pulse D-STATCOM using PLL Controller compare to the SRF Controller techniques to alleviate the fast-varying voltage flicker.

Alleviation of Power Quality Issues Caused by Electric Arc Furnace Load in Power Distribution System Using 3-Phase Four-Leg DSTATCOM

Electric Arc Furnaces (EAFs) play an essential role in the production of superior quality steel, using metal scrap as raw material. However due to its non-linear electrical characteristics, it creates lot of power quality problems in the 3-phase 4-wire power distribution system. In this paper, time domain based hyperbolic EAFs model is considered as an unbalanced, time-varying non-linear load and the power quality issues created by EAF are considered. A four-leg distribution static compensator (FL-DSTATCOM) is utilized for elimination of current harmonic and 3-phase current imbalance. Simultaneously, it nullifies the current flow in the neutral conductor, compensate the reactive power and rectify the poor PF which are caused by the EAFs in the power distribution system. The FL-DSTATCOM injects reactive and harmonics components of furnace current extracted using synchronous reference frame theory. In order to evaluate the compensation capability of FL-DSTATCOM under static and dynamic furnace loading conditions, the digital simulation is carried out using MATLAB/SIMULINK. The simulation results demonstrate that the FL-DSTATCOM is capable of making the supply current balanced and sinusoidal. It also helps in maintaining the power factor at point of common coupling near to unity and reduces the supply neutral current very close to zero.

An Experimental Approach for Understanding V-I Characteristic of Electric Arc Furnace Load

Electric Arc Furnaces (EAF) are nonlinear loads causing power quality problems on the systems they are connected to. The main reason of EAFs causing power quality problems is the nonlinear characteristics of the electric arc. In this study, dynamic working characteristics of electric arc furnace load at Sivas Iron and Steel Incorporated Company (SIDEMIR) operating with 60 MVA EAF have been experimentally examined by HIOKI 3197 PQ analyser. Utilizing the measured dynamic load curves, mathematical equation and proper parameters have been determined for modelling electrical arc with the help of curve fitting methods on Matlab program. Also by modeling a phase equivalent of the system and harmonic filters existing on the system, a time domain model has been formed and with this model, harmonic effects of the EAF have been examined with Matlab/Simulink. Simulation results show that the presented model can be used for examining PQ and voltage harmonics problems caused by EAF loads.DOI: http://dx.doi.org/10.5755/j01.eie.23.3.18328

Correlation Between Multiple Electric Arc Furnace Operations and Unscheduled Power Flows in the Interconnection Lines at the Eastern Cross Border of ENTSO-E

In this paper, the correlation between unscheduled power flows in the interconnection lines at the eastern cross border of the European Network of Transmission System Operators for Electricity (ENTSO-E) and multiple electric arc furnace (EAF) operations in Turkey has been assessed. Turkey is interconnected to ENTSO-E at the eastern cross border via Greece and Bulgaria, with a 400-MW export and a 550-MW import agreement. In order to determine the degree of the relationship between the unscheduled power exchange between Turkey and Europe, and the multiple high-power EAF operations, Pearson correlation method has been employed. For this purpose, time-synchronized data of active power consumption have been collected from 17 major EAF plants during 1 week with a time resolution of 3 s, by using custom-design, synchronized power-quality (PQ) analyzers. A total peak-power consumption of nearly 1.5 GW of multiple EAF loads has been recorded. The results obtained have been evaluated by the use of the National Power Quality Monitoring System of Turkey, which continuously monitors the power flows in the interconnection lines of the ENTSO-E by PQ analyzers. The rate of change in total EAF power consumptions higher than 200 MW in less than 15 s against the rate of change in area control error (ACE) index is found to be closely correlated to each other, with a Pearson correlation coefficient (CC) of 0.8. Since the response of the frequency restoration reserve of power plants is much slower, such rapid fluctuations in the power consumption of multiple EAFs collectively result in uncontrollable power flows in the interconnection lines at the eastern cross border of ENTSO-E.

A comparative study of modelling AC electric arc by one-dimensional interpolation for power system harmonics analysis

Electric arc is a discharge phenomenon caused by particular electrical events and arc produced facilities in power system, for example the occurrence of short-circuit fault in feeders and the use of electric arc furnace for steel-making. All of these electric arcs have a highly nonlinear nature and can be considered as a significant source of power quality problems. To investigate the impacts of the electric arcs on power quality studies the development of the electric arc models for simulation analysis is became necessary. This paper thus presents the use of different one-dimensional interpolation methods for modelling the alternating current electric arc. The performances of different methods are compared by simulation results that are derived from the modelling of an alternating current electric arc furnace load and a low-frequency fluorescent tube.

A Novel Delay-less Control of Unified Power Quality Conditioner to Enhance Power Quality in Power System

In this article, an analytical and delay-less model for the unified power quality conditioner is proposed to improve electrical power quality in power systems. The designed model includes a shunt active filter, series active filter, and common DC link, which is capable of improving power quality parameters in different conditions. The proposed control is based on a combination of the rotating reference frame theory and least mean square method that (1) can enhance power quality, including reduction of the voltage and current harmonics, voltage flicker, and reactive power of system, and (2) has no delay in the reference current generation. The DC link is also designed in a manner that capacitor voltage has a stabilized voltage in all instants. In addition, fundamental frequency estimation is employed to control frequency changes in the control system. For testing the proposed method in the worst conditions, the electric arc furnace load based on an actual stochastic arc that can generate almost all electrical power quality parameters is taken into account for the power system. The validity of proposed method is analyzed by comparing different existing control methods of the unified power quality conditioner. The simulation results show the accuracy of the control system.

Voltage Flicker Mitigation in Electric Arc Furnace using D-STATCOM

The major power quality issue of voltage flicker has resulted as a serious concern for the customers and heavy power companies. Voltage flicker is an impression of unsteadiness of visual sensation induced by a light source whose luminance fluctuates with time. This phenomenon is experienced when an Electric Arc Furnace (EAF) as load is connected to the power system. Flexible AC transmission devices (FACTS) devices were gradually utilized for voltage flicker reduction. In this paper the FACTS device of Distribution Static Synchronous Compensator (D-STATCOM) is used to serve the purpose of mitigating voltage flickering caused by electric arc furnace load, which is efficiently controlled by Icosɸ control algorithm. The model of electric arc furnace is considered as a current source controlled by a non linear resistance, which had been simulated and performance was analyzed using MATLAB/SIMULINK Software. DOI: http://dx.doi.org/10.11591/ijpeds.v5i2.6242

A Hybrid Wavelet Transform and Neural-Network-Based Approach for Modelling Dynamic Voltage-Current Characteristics of Electric Arc Furnace

This paper proposes a discrete wavelet transform (DWT) and radial basis function neural network (RBFNN)-based method for modeling the dynamic voltage-current (v- i)characteristics of the ac electric arc furnace (EAF). The objective of the study is to develop a complete model of the EAF including different operation stages, and the model can be used as a harmonics and flicker source in its connected power system for the power-quality penetration or mitigation study, where the developed model can be embedded in the power system implemented by a commonly seen simulation tool, such as Matlab/Simulink. In the study, a combination of the DWT and the sequential RBFNN with parameters initialization algorithm is proposed to build the EAF v- i characteristics with enhanced lookup tables for different operation stages, where the field measurements of the EAF voltage and current are used to train the RBFNN for modeling the EAF load. Simulation results obtained by using the proposed model are compared with different measured data. It shows that the solution procedure accurately models the EAF dynamic v- i behavior. The proposed method also can be applied to model other highly nonlinear loads to assess the effectiveness of compensation devices or to perform relative penetration studies.

Forecasting Flicker Severity by Grey Predictor

Rapid voltage fluctuations in an electric power network may produce significant levels of flickers, which have negative impacts on human eyes and power system components. This paper proposes a grey predictor model for the forecast of the flicker severity level associated with operating a large electric arc furnace load. Actual measured flicker index data are adopted to implement the predictor model. Test results based on the proposed model are compared with another neural-network-based method. It shows that a more accurate forecast is achieved by using the proposed grey predictor model.

On Real-Time Simulation for Harmonic and Flicker Assessment of an Industrial System With Bulk Nonlinear Loads

This paper presents application experiences of real-time simulation (RTS) techniques for harmonic and flicker studies of an industrial power system, where the system and nonlinear loads are properly modeled. A PC-cluster-based real-time parallel simulator is implemented under MATLAB/SIMULINK, where the studied system consists of an ac electric arc furnace, dc and ac motor-drive loads, and the static var compensator. Guidelines for model partition of the studied system and the solver settings under an RTS environment are reported. In addition, the most commonly used offline simulation with variable-step solver and the actual field measurements are included for comparison. Results indicate that the RTS achieves satisfactory solution accuracy within much less execution time and can be applied for more complicated studies such as installing new nonlinear loads with different levels of model complexities or designing/tuning mitigation devices of power-quality disturbances, where the repeated time-consuming analysis is required.

A Neural-Network-Based Method of Modeling Electric Arc Furnace Load for Power Engineering Study

It is known that artificial neural network is a powerful scheme for function learning and modeling nonlinear loads. However, a direct application of artificial neural network for modeling time-varying loads may lead to inaccuracies. This paper presents an accurate neural-network-based method for modeling the highly nonlinear voltage-current characteristic of an ac electric arc furnace (EAF). The neural-network-based model can be effectively used to assess waveform distortions, voltage fluctuations, and performances of reactive power compensation devices associated with the EAF in a power system. Simulation results obtained by using the proposed model are compared with the actual measured data and two other traditional neural network models. It is shown that the proposed method yields favorable performance and can be applied for modeling similar types of nonlinear loads for power engineering studies.

Curve-fitting-based method for modeling voltage–current characteristic of an ac electric arc furnace

Field measurements of voltage and current are the most effective way for characterizing the electric response of an ac electric arc furnace that describes its nonlinear behavior. Sufficient measured information can be adopted to determine the background harmonic level in a power system, to characterize specific sources of harmonics, and to develop an appropriate nonlinear voltage–current characteristic. In this paper, a curve-fitting-based method called cubic spline interpolation is proposed to model the voltage–current characteristic of an ac electric arc furnace in the steady state. Meanwhile, the actual measured data are collected for modeling use. Two classic methods, harmonic current injections and equivalent harmonic voltage sources, for modeling the electric arc furnace load are reviewed and used to evaluate the performance of proposed model. Results obtained from the measured data and computer simulations of the three electric arc furnace models are then compared according to the voltage and current waveforms, as well as the voltage–current characteristic. It is shown that the proposed model is more accurate than the two classic approaches for harmonic assessment of electric arc furnaces and can be used for modeling similar types of nonlinear loads in the harmonic penetration study.

Fuzzy-Wavelet-Based Electric Power Quality Assessment of Distribution Systems Under Stationary and Nonstationary Disturbances

Evaluating the electric power quality (EPQ) becomes very important task due to the widespread use of nonlinear loads, distributed energy resources (DERs) and the economic impact of poor EPQ. In a deregulated environment, having different power quality indices (PQIs) with different values has no significance unless they are combined into single value that could represent them. In this paper, a new fuzzy-wavelet packet transform based PQI is introduced that amalgamates the recommended PQIs after being redefined in the time-frequency domain using wavelet packet transform for compatibility purposes with nonstationary disturbances. In order to handle the uncertainties associated with the electric power system operations, fuzzy systems are used in this paper. In order to study the effect of wavelet filter length and the choice of the best wavelet basis function, the new fuzzy developed modules along with the reformulated PQIs are used in three case studies considering electric arc furnace load supplied from stationary low distorted voltage, stationary high distorted voltage and nonstationary distorted voltage (voltage dip) in addition to a real case study considering variable speed drive.

실측에 의한 특고압 수용가의 고조파 평가에 관한 연구

전기로를 포함하는 비선형 부하를 가진 규모가 큰 제철소는 특고압 수용가이다. 이득 비선형 부하는 고조파 전류를 발생시키고, 전력계통의 전압을 왜곡시킨다. 고조파 측정결과로 고조파는 시간에 따라 변하는 특성을 가지고 있었다. 시간에 따라 변하는 고조파를 해결하기 위해 쓰이는 가장 보편적인 방법은 누적확률을 사용하는 것이다. 본 논문에서는 전기로 부하의 시간에 따라 변하는 고조파를 국제 고조파 기준인 IEC 61000-3-6, IEEE 519와 JIS C 61000-3-2에 의해 평가하고자 한다.

A Study on the Harmonics Effect of SVC in Electric Arc Furnace Loads

Large steel industries have time-varying nonlinear loads such as electric arc furnaces. These nonlinear loads generate harmonic currents and create distortions on the sinusoidal voltage of the power system. The main objective of the static var compensator is to maintain the rms voltage at the point of common coupling within the limit. In this research, harmonic mitigation studies were conducted with and without the SVC, and time-varying harmonics were evaluated according to the international harmonic standards (IEC 61000-3-6 and IEEE Std. 519) using a cumulative probabilistic approach.

전기로 부하에서 SVC의 플리커 효과에 관한 연구

제철소에서 사용되고 있는 전기로는 전력계통에 전압 변동을 일으키며 시간에 따라 변하는 비선형 부하이다. 플리커는 전압 변동의 크기에 따라 램프의 방출 변화에 의한 인간의 지각 효과로 정의된다. 플리커 레벨은 전압 변동의 크기, 주파수 및 기간에 의해 결정된다. 본 논문에서는 전기로 부하로 인한 154[kV] 시스템에서의 전압 변동 문제를 측정하고, 플리커 저감을 위한 SVC 적용 결과를 분석하고, IEC 61000-3-7에 의하여 플리커를 평가하였다.

전기로 부하의 고조파 측정, 평가 및 동조필터 적용에 관한 연구

규모가 큰 제철소는 전기로를 포함한 비선형 부하를 가지고 있다. 이들 비선형 부하는 고조파 전류를 발생 시키고, 전력 계통의 전압을 왜곡시킨다. 본 논문에서는 전기로 부하의 고조파 현장 측정, 고조파 저감을 위해 수용가 모선에 동조 필터 적용과 국제 고조파 관리 기준인 IEC 61000-3-6과 IEEE Std. 519에 의한 고조파 평가를 심도 있게 분석한다. 고조파 해석 프로그램인 EDSA는 사례연구에 시뮬레이션 도구로 사용되었다.

시간에 따라 변하는 전기로 부하의 고조파 측정, 평가 및 시뮬레이션에 관한 연구

Large steel industries have nonlinear loads such as electric arc furnaces. Harmonic field measurements have shown that the harmonic contents of a waveform varies with time. Direct application of the harmonic assessment to the snapshot measurements would result in ambiguous conclusions depending on which instant is sampled. A cumulative probablistic approach is the most commonly used method to solve time-varying harmonics. Harmonic simulations are performed to evaluate the harmonic voltage and current distortions throughout the system. This paper provides an in depth analysis on harmonics field measurement of the electric arc furnace loads, harmonics assessment by the international harmonic standards IEC 61000-3-6 and IEEE Std. 519 and harmonic simulation for the time-varying harmonics. The EDSA program was used as a simulation tool for the case study.

Enhancement of static excitation system performance for generators near electric arc furnace loads

The tuning of static excitation systems (SESs) to enhance the performance of six gas turbine (GT) generators near an electric arc furnace (EAF) feeder has been successfully accomplished. The operation of these EAFs causes severe and long duration voltage fluctuations at the generator bus. Frequent generator tripping was reported when the adjacent EAFs were in operation. Preliminary field measurements and computer simulations indicated that the SESs did not have sufficient damping under this type of voltage fluctuation. By the adjustment of the SES gains and time constants according to the guideline set by the IEEE Standard 421.2, the SES damping can be greatly improved. This has been verified by additional field tests on six GT generation units. Now these generators can be operated very well although the EAFs still cause voltage fluctuation.