Measuring method and device for DC electric arc furnace short-circuit inductance

Abstract

The invention discloses a method and device for measuring the inductance of a DC electric arc furnace short network. The method includes: controlling a DC electric arc furnace rectifier to apply a voltage signal with a preset amplitude to two poles of a DC electric arc furnace, and collecting a DC electric arc furnace short network The first current data in the process of raising the current from zero to the preset current value; control the rectification device of the DC arc furnace to stop applying the voltage signal of the preset amplitude to the two poles of the DC arc furnace, and collect the short-circuit current of the DC arc furnace from the preset The second current data whose current value drops to zero; perform a fitting process on the collected first current data and the second current data to obtain an estimated value of the short-circuit inductance of the DC electric arc furnace; repeat the above steps for many times, the Multiple estimated values ​​obtained from multiple fitting processes are recursively processed to determine the inductance value of the DC electric arc furnace short network corresponding to the preset current value. The invention can accurately measure the actual inductance of the DC electric arc furnace short network.

Description

technical field [0001] The invention relates to the field of industrial smelting, in particular to a method and device for measuring short-circuit inductance of a DC electric arc furnace. Background technique [0002] This section is intended to provide a background or context to embodiments of the invention that are recited in the claims. The descriptions herein are not admitted to be prior art by inclusion in this section. [0003] An electric arc furnace is an electric furnace that uses high temperatures generated by electrodes to smelt ores or metals. For the power grid, the electric arc furnace is a nonlinear load. The smelting process of the electric arc furnace will bring problems such as reactive power impact, unbalanced three-phase voltage, and harmonic pollution to the power grid, causing severe fluctuations in the power grid voltage. Compared with AC electric arc furnaces, DC electric arc furnaces have much less impact on the grid. [0004] figure 1 A schemati...

AI Technical Summary

Problems solved by technology

[0010] Since the overall equipment cannot be tested independently, the inductance value of the electric arc furnace short-circuit device will seriously deviate from the factory value given by the equipment manufacturer in actual engineering

Especially after long-distance transportation of the equipment as a whole, the structure of the electric arc furnace short network device will also change. The equipment manufacturer originally adopted the model of the finite element method, and many changes have taken place in the structure of the field equipment, resulting in the results of the finite element technique having no reference value at all.

However, the equipment manufacturer can only use the reference value of the short-circuit inductance of the electric arc furnace through segmental measurement, and then simplify the calculation through electrical. After multiple sub-equipment are connected through cables or copper bars and aluminum bars, the electrical parameters have also changed. This cannot be measured on site

[0011] At the same time, due to the large heating power of the short-circuit equipment of the electric arc furnace, it needs to be cooled with deionized water. The parameter changes caused by the water cooling device lead to too much simplification of the electrical model, and the inductance value of the current short network will also change greatly

[0012] From the above analysis, it can be seen that the existing technology adopts the small signal detection method to measure the short-circuit inductance of the electric arc furnace, ignoring the change of the equipment magnetic field caused by the large current, especially the effect of the electrical eddy current, which leads to deviations in the measurement of the short-circuit inductance of the DC electric arc furnace

In addition, this method is seriously affected by the external magnetic field, and the same device is tested multiple times. Due to the change of the external magnetic field, the detection results change greatly, and a correct device parameter value cannot be given.

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