Research On Soft Measurement For Arc Current Of Electric Arc Furnace

Electric arc furnace steelmaking has been applied wildly and become one of the most important steelmaking methods for its several advantages such as make the most use of steel scrap resource, shortness of steelmaking process, lowness of steelmaking consumption of energy per ton of steel, fit to the situation of sustainable development of international iron and steel industry. The arc current and arc voltage are the input of the electrode controller which is the principal section of the electric arc furnace control system. It is the premise of assuring the normal working of electrode controller that arc current and arc voltage are measured accurately. But how arc current and arc voltage to be measured economically and accurately is still an available subject of present stage.The background of the paper is based on Tonghua Iron and Steel Co. Ltd 120t electric arc furnace. Soft measurement methods for arc current and arc voltage are researched, soft measurement models for arc current and arc voltage are established, an economic and accurate measurement for arc current and arc voltage is achieved.Based on the theory of transformer, mechanical models of instantaneous value and effective value of arc current and arc voltage are established. The relationship between arc current and arc voltage to the primary side current and voltage of furnace transformer and whole active power of three-phase load is gave out, the availabilities of these models are analyzed by simulation.According to the drawbacks of mechanics modeling process that the models have large errors because the no-load current of transformer and nonlinear coupling between the three phase electrodes are neglected, based on the characteristic of furnace transformer, an soft measurement model for arc current and arc voltage based on Partial Least Squares regression is established, and the simulation shows that the fitting effect of the PLS model use the data of same arc voltage setting is better than the mechanics model. According to the shortcoming that the generalized performance when the data of different arc voltage setting are tested by the PLS model is not good, another soft measurement model for arc current and arc voltage based on the classifying Partial Least Squares regression is put forward, the simulation shows that the accuracy and generalized performance of the classifying Partial Least Squares regression model are improved greatly, it is in accordance with the standard of the engineering applications.