Modelling and Identification of a Three-Phase Electric Arc Furnace

This chapter is an attempt to illustrate the development of a mathematical model of an industrial process by combining analytical modelling techniques with a system identification study. Although both these approaches can often be applied in isolation to develop a mathematical description of a process the lack of detailed knowledge of the high power arc discharge suggests a combination of these techniques in the case of an electric arc furnace. The objective of the present study is to develop three-phase models of both arc impedance and arc current controlled electric arc furnaces. Initially, a single-phase model of the electrode position controller, arc discharge and furnace transmission system are developed for an arc impedance controlled furnace using analytical modelling techniques and assuming zero interaction between the three regulators. Th assumptions and approximations associated with this model are investigated by designing experiments and conducting tests on a production arc furnace. Properties of the arc discharge, interaction between the regulators and a pulse transfer function representation of the electrode position controller are identified. These results are extended and three-phase models of an arc impedance and arc current controlled electric arc furnace are derived

On the long-term correlations and multifractal properties of electric arc furnace time series

In this paper, we study long-term correlations and multifractal properties elaborated from time series of three-phase current signals coming from an industrial electric arc furnace plant. Implicit sinusoidal trends are suitably detected by considering the scaling of the fluctuation functions. Time series are then filtered via a Fourier-based analysis, removing hence such strong periodicities. In the filtered time series we detected long-term, positive correlations. The presence of positive correlations is in agreement with the typical V--I characteristic (hysteresis) of the electric arc furnace, providing thus a sound physical justification for the memory effects found in the current time series. The multifractal signature is strong enough in the filtered time series to be effectively classified as multifractal

Identification Of Harmonic Source For Electric Arc Furnace Load Using Fast-Fourier Transform

Harmonic pollution has become a major problem in electrical power networks which can cause problems like the reduction load’s lifetime, failure of protection devices to operate efficiently, instabilities of power system interference in operating systems and all these can contribute to economic losses and downtime. Therefore, harmonic source identification is one of the major problems. Proper identification of the harmonics source is an essential for developing penalty based schemes for harmonic generation and for the design of mitigation equipment to reduce harmonic. This dissertation aims to identify and analyze the harmonics source in power system using Fast-Fourier Transform (FFT) with effective cost efficiencies using single-point measurement approach. The sources of harmonic that been focused in this study is Electric Arc Furnace and finally, the applicability of the modelling system is tested with another harmonic source, Rectifier. The signification finding of this research shows the harmonic sources location can be identified by referring to the relationship between fundamental impedanc

Long-term diffusion factors of technological development - an evolutionary model and case study

In the first part of this article, a short description of the most popular models of two competing technologies (the Fisher-Pry model and its modifications proposed by Blackman, Floyd, Sharif and Kabir) and the multi technological substitution models of Peterka and Marchetti-Nakiæenoviæ are presented. In the second section, we describe an evolutionary model of diffusion processes based on biological analogy, together with the method of its parameters’ identification using real data on technologies development. In the final sections the applications of that model to describe the real diffusion processes (namely, primary energy sources in the world energy consumption and the raw steel production in the United States) are presented. The feasibility of using the model to predict future shares of given technologies and to build alternative scenarios of future evolution of structure of the market is suggested.diffusion; substitution; evolution; simulation; s-curve; logistic curve; logistic function

Advances in the Analysis of Properties Behaviour of Cement-Based Grouts with High Substitution of Cement with Blast Furnace Slags

This article presents a study of the main properties (consistency, workability, leaching, unsoundness, and mechanical properties) of cement grouts prepared with cement replacement by blast furnace slag (GGBS). Mixtures have been analyzed in the absence of additives and reached high replacement percentages. As shown in the different tests presented, the observed evolution of the resistance and workability of the mixtures makes them very interesting for its application. Different types of cement (CEM-I 42.5 and CEM-I 52.5 R) and different water/binder values (1 and 0.67) are used. The results present opportunities for the steel industry by the intensive valorization of slag waste. The reduction of the use of cement in construction is also one of the key aims of this line of research. Results show improvements in the mechanical response with good fresh state properties for substitution percentages up to 70%. It is verified with leaching analysis that these products have less impact on the environmen

Comparison between unipolar and bipolar single phase grid-connected inverters for PV applications

An inverter is essential for the interfacing of photovoltaic panels with the AC network. There are many possible inverter topologies and inverter switching schemes and each one will have its own relative advantages and disadvantages. Efficiency and output current distortion are two important factors governing the choice of inverter system. In this paper, it is argued that current controlled inverters offer significant advantages from the point of view of minimisation of current distortion. Two inverter switching strategies are explored in detail. These are the unipolar current controlled inverter and the bipolar current controlled inverter. With respect to low frequency distortion, previously published works provide theoretical arguments in favour of bipolar switching. On the other hand it has also been argued that the unipolar switched inverter offers reduced switching losses and generates less EMI. On efficiency grounds, it appears that the unipolar switched inverter has an advantage. However, experimental results presented in this paper show that the level of low frequency current distortion in the unipolar switched inverter is such that it can only comply with Australian Standard 4777.2 above a minimum output current. On the other hand it is shown that at the same current levels bipolar switching results in reduced low frequency harmonics

Comparison between unipolar and bipolar single phase grid-connected inverters for PV applications

An inverter is essential for the interfacing of photovoltaic panels with the AC network. There are many possible inverter topologies and inverter switching schemes and each one will have its own relative advantages and disadvantages. Efficiency and output current distortion are two important factors governing the choice of inverter system. In this paper, it is argued that current controlled inverters offer significant advantages from the point of view of minimisation of current distortion. Two inverter switching strategies are explored in detail. These are the unipolar current controlled inverter and the bipolar current controlled inverter. With respect to low frequency distortion, previously published works provide theoretical arguments in favour of bipolar switching. On the other hand it has also been argued that the unipolar switched inverter offers reduced switching losses and generates less EMI. On efficiency grounds, it appears that the unipolar switched inverter has an advantage. However, experimental results presented in this paper show that the level of low frequency current distortion in the unipolar switched inverter is such that it can only comply with Australian Standard 4777.2 above a minimum output current. On the other hand it is shown that at the same current levels bipolar switching results in reduced low frequency harmonics