.12500 KVA Submerged Arc Furnace Power Supply System Parameter Calculation And Analysis Of Load Characteristics

Submerged arc furnaces are widely used in the metallurgy industry. They are high-power devices and their power consumption takes a large part of the total cost of the production. Because of the non-linearity of the electric arc, changes of the minerals during the ferroalloy smelting process and the fluctuation of the working conditions, the submerged arc furnace are unstable, which not only affects the quality of the production, but also increases the power consumption. Therefore, studying the parameter calculation of the submerged arc furnace power supply system and the load characteristics are of great important to the control of the smelting process, the improvement of working conditions, the increase of efficiency and quality and reduction of energy consumption. In this paper, a 12500kVA submerged arc furnace and its power supply system are studied. The parameter calculation and the load characteristics are analyzed.Each part of low-voltage side of the power supply system is analyzed and their parameters are calculated using their equivalent circuits, respectively. The computing model is established, focusing on studying of the influence of the three-phase asymmetrical copper network impedances'asymmetry, which are caused by the asymmetry of location and length of the copper network, results in the unbalance of the three-phase pool power on the condition that the three-phase electrode currents are balance.Since the power zero point on high-voltage side of the medium-size transformer and the central point of the molten pool of the submerged arc furnace are not draw out, the three-phase electric parameters of each phase are difficult to measure. Therefore, in order to measure the phase voltages of the power supply system and electrodes, a solution of constructing the power zero point on high-voltage side of the transformer and the central point of the molten pool on the low-voltage side of the transformer respectively is proposed. A three-phase load model is established to analyze the changes of the phase electric parameters and the influence of the load characteristics on the working conditions during the smelting process. And the analyses show that load characteristics would reduce the power factor, affect the imbalance of the three-phase power, and increase the power consumption during the smelting process.Using the measured data and a curve fitting technique based on cubic spline interpolation method, a u-i load characteristic model of the submerged arc furnace is established to analyze the load characteristics in different operating conditions and different smelting stages during the smelting process. The influence of the different electrode positions on the power qualities which are evaluated by the voltage deviation, voltage fluctuation and three-phase power imbalance is analyzed. And the results show that the voltage deviation, the voltage fluctuation and severe three-phase power imbalance would increase the power consumption during the smelting process which provides valid information for optimizing the operations of the submerged arc furnace.