Modeling Of Arc Furnace Electric System And Its Harmonic Suppression Method Analysis

With the increasing demand for special steels in emerging fields,ultra high power electric arc furnace,which can smelt high quality steel,ushered in the development of spring.With the improvement of the capacity of single-arc electric arc furnace and the widespread use of AC electric arc furnace,the harm of electric arc furnace to the power quality of power grid becomes more and more prominent,Therefore,it is urgent to control the electric energy pollution in its operation.Firstly,this paper studies the mechanism of power quality problems such as voltage fluctuation and flicker,harmonics and low power factor caused by arc furnace smelting process.And through mathematical modeling,simulation,quantitatively evaluate the impact of electric arc furnace operation process on power grid.In the research process,the nonlinear time-varying resistance model with arc-radius variation was optimized.A new type of AC arc resistance model(L-Q model)is proposed based on the arc length L and the arc energy Q as the input.Compared with the measured data,quantitative simulation analysis of current harmonic injected into the grid and power factor during operation of L-Q model.Then,this paper studies the structure and principle characteristics of the common filter device,and combines the composition and content of the injected harmonic wave to design the topological structure of the filter device.Consider the TCR itself will produce harmonics and FC on the fundamental near the low-frequency harmonic filtering effect is poor,using APF and SVC joint filtering,and APF connected to the power supply side,SVC connected to the load side.Aiming at the voltage distortion and three-phase imbalance of AC arc furnace load in smelting process,on the premise of extracting fundamental positive sequence voltage,Steinmetz theory and the phase-separate compensation method of symmetrical component method and is used to control the reactive power compensation device.Theoretical analysis of this filter compensation device can improve the three-phase load imbalance,eliminating negative sequence current.Finally,the simulation model of the system filtering device is established and the simulation load of the three-phase dynamic arc furnace is connected.When the dynamic model distortion rate is small,similar to the electric arc furnace system works in the reduction period,only put active filter,you can achieve harmonic filtering,can greatly reduce the fundamental loss.For the main melting phase with large distortion rate and unbalanced three phases,APF and SVC need to be put into operation at the same time.The simulation analysis filter can better compensate the power factor of the EAF system,reduce the voltage and current harmonic distortion,and achieve the harmonic suppression of the EAF system.