Characteristics of Intelligent Electric Power Supply System for Electric Arc Furnace

Power supply operation is one of the main links in the electric arc furnace steelmaking process. At the same time, the key to optimizing the power supply lines in the automatic adjustment of electrodes. In order to improve the response speed and control accuracy of electrode adjustment, ensure the balance of the three-phase current of the arc furnace and the continuous and stable adjustment of the electrode, it is necessary to continuously improve the electrode adjustment system of the arc furnace, so as to achieve the goals of energy saving, consumption reduction, and improvement of output and quality. The development of automatic determination of scrap melting technology has further improved the intelligent level of electric arc furnace power supply.

1. Intelligent adjustment of electrodes

At present, the research on the adaptive control of electric arc furnace electrode adjustment in China and most other countries is mainly to identify and control the main circuit of the electric arc furnace as a linear system, and then use the adaptive method of the linear system for research. The piecewise linearization adaptive control method is one of them. The piecewise linearization adaptive control strategy is to transform the electric arc furnace electrode adjustment system from the control of the nonlinear system to the control of the piecewise linearization system. Solve the self-adaptive control problem of the three-phase electric arc furnace system.

With the rapid development of intelligent control principles, researchers have widely used intelligent control algorithms to control the adjustment of electric arc furnace electrodes. Aiming at the complex nonlinearity and time-varying characteristics of the two periods of electric arc furnace smelting, the researchers used neural network and fuzzy control combined with traditional PID control methods to achieve satisfactory control results in each period of smelting. The American Polaris Steelmaking Company uses intelligent control algorithms to improve the electrode control system of the 80t electric arc furnace, which increases productivity by 10%-20%, reduces electrode consumption by 0.4-0.6kg/t, and reduces electrical energy consumption by 18-20kWh/t. . After a 100t electric arc furnace electrode system of a Chinese steel company uses a constant impedance neural network to adjust, the power supply time per furnace is shortened by 8min, and the power consumption is reduced by 60kWh/t.

2 Automatically determine the scrap melting technology

Modern electric arc furnace steelmaking generally adjusts electricity according to a preset power-on chart, and the smelting process must be filled with scrap steel many times. However, because the properties (such as size, volume, weight, shape, etc.) and melting conditions of the loaded scrap steel often change, operating in accordance with the preset power-on chart cannot achieve the best power supply melting effect. Especially in the period of adding scrap steel and the period of smelting from melting to heating, the operators are often operated based on experience. Therefore, the inaccurate judgment of the melting period will increase the smelting time and reduce the production efficiency. The accurate grasp of the melting state of scrap steel in the electric arc furnace will have a greater impact on the steelmaking operation. In this context, Japan's Datong Special Steel Co., Ltd. developed an E-adjust system for electric arc furnaces to automatically determine the melting of scrap steel. Mainly use the two elements of high-order harmonic current (or high-order harmonic voltage) and electric arc furnace sound generated in the electric arc furnace smelting process to determine the melting state of the scrap steel in the furnace, and then carry out automatic control. Datong Special Steel has collected a large amount of E-adjust actual production data and compared it with the traditional manual judgment and clear production mode. The comparison of operating parameters shows that the average power consumption of the electric arc furnace has been reduced by 7.1kWh/furnace, and the operating time has been reduced by 0.4min. , After the introduction of the E-adjust system, it saves electricity due to stable operation and improves the production efficiency of the electric arc furnace.

In recent years, the electrode automatic adjustment model based on adaptive technology, neural network, and fuzzy control has been gradually introduced into the domestic electric arc furnace control system, and the actual production effect is remarkable. As domestic electric arc furnace steelmaking widely uses hot metal charging technology, the automatic determination of scrap melting technology must be further improved to adapt to the electric arc furnace steelmaking process with different scrap ratios and improve its reliability.

It can be seen that the intelligent power supply system of electric arc furnace has improved the intelligent level of electric arc furnace power supply, and has also greatly improved various indicators and performance.

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Daisy Zhai