High-performance direct-current power supply implementation method of direct-current electric arc furnace

Abstract

The invention provides a high-performance direct-current power supply implementation method of a direct-current electric arc furnace, belongs to an electric direct-current power supply and direct-current electric arc furnace melting technique and aims to develop an AC ( alternating current) / DC (direct current) converter with low harmonic wave, high power factor and adjustability of direct-current voltage and current in a large range. The high-performance direct-current power supply implementation method is characterized in that a high-performance direct-current power supply comprising a phase-shifting transformer, a twelve-pulse-wave converter bridge formed by two completely identical thyristor six-pulse-wave converter bridges (5) and (6) and a multi-level direct-current current control and synthesis unit (7) adopts an asymmetric current control strategy to control current waveforms of two three-phase converter bridges through the multi-level direct-current current control and synthesis unit (7) according to specific conversion rules of a formula (1) and a formula (2), so that three-phase alternating-current input current of the converter is sine-wave current, and a direct-current power supply has the characteristics of low harmonic wave, high power factor and continuous adjustability of direct-current side voltage and currents in a large range and can be used for a high-performance direct-current power supply system of newly-built and improved direct-current electric arc furnaces.

Description

technical field [0001] The invention belongs to electric DC power supply and DC electric arc furnace smelting technology. Background technique [0002] Compared with AC electric arc furnace, DC electric arc furnace has good arc stability, less flicker, low electrode consumption, low noise pollution, low power consumption, light burning of furnace wall refractory materials, long arc length, and electromagnetic stirring effect. Good quality, short smelting time, easy operation and other advantages, as well as the rapid development of power electronics at that time, since the end of the 1980s, the climax of the application of DC arc furnaces in the metallurgical field has risen. In the next two decades, DC Arc furnaces are used in a large number of applications. [0003] DC electric arc furnace is an effective way to save energy and reduce consumption of electric furnace. The actual application results show that compared with AC electric arc furnace, DC electric arc furnace ca...

AI Technical Summary

Problems solved by technology

[0006] (1) The 6-pulse or 12-pulse thyristor rectifier will still generate large harmonics and low power factor during the actual operation of the DC arc furnace, especially in the middle and late stages of smelting, due to the reduction of smelting load, the thyristor The power factor of the rectifier system becomes worse, and the harmonics become larger. A certain amount of reactive power compensation devices and filter devices still need to be invested, but the investment is less than that of AC electric arc furnaces, but a considerable investment is still required

[0007] (2) The current 6-pulse or 12-pulse thyristor rectifier device can adjust the DC current relatively quickly, but the ability to adjust the voltage is very limited. Therefore, the adjustment of the arc voltage in the actual operation of the electric arc furnace still depends on the adjustment The lifting of the electrode is controlled, that is, in the heating power control of the smelting process, it has little advantage compared with the AC electric arc furnace.

[0008] (3) The current 6-pulse or 12-pulse thyristor rectifier device does not have the potential to provide excavable production capacity for the smelting process, that is, it does not have the potential ability to break the game balance between the DC electric arc furnace and the AC electric arc furnace. The ability is specifically reflected in whether it can provide effective control means for smelting optimization for the smelting process

[0009] In summary, the current DC power supply of DC electric arc furnaces has performance problems such as large harmonics, poor power factor, and poor controllability of DC output voltage. Can a simple, economical and effective method be found to achieve a more ideal DC electric arc furnace DC power supply? This is an important topic faced by the DC electric arc furnace DC power supply technology research institute, and no innovative research results have been seen so far

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