The Research On A New Type Electric Arc Furnace Power System With Dynamic Compensation Function

AC electric arc furnace equipment is being widely used in the metal smeltingindustry. Equipment operates with characteristics of low voltage, high current and thedynamic changes of load. And there are some power quality problems, such as lowpower factor, large harmonic content and load imbalance of three-phase. It may alsocause voltage fluctuations and flicker. The traditional fixed compensation methodcan’t meet operational characteristics of AC electric arc furnace. In order to solve theabove-mentioned problem, a new type electric arc furnace power system is proposedwhich combines the STATCOM devices with the induction filtering transformer. Thenew system can solve the present problems better. The main researchers are asfollows:(1) A chaotic model to facilitate the analysis of power quality problems isestablished under the analysis of the characteristics of work and operating. The newmodel will obtain the essential reason of the power quality problems caused by theEAF from a deeper level.(2) The topology of the new type electric arc furnace power system with dynamiccompensation function is proposed for the existed power quality problems in thetraditional electric arc furnace. Then a detailed analysis on the characteristics of theworking principle and structure is made in this paper especially on the inductionfiltering transformer and STATCOM.(3) The key to achieve dynamic compensation function is to have an effectivecontrol of the STATCOM equipment in the new type electric arc furnace powersystem. And the way to achieve the basic function of STATCOM is to have anaccurate detection to voltage and current of the system. This paper proposes a methodfor detecting the current and voltage of the system and carries out a detailed analysisand introduction of the detection method based on instantaneous power theory p-qmethod and ip-iq method. Based on instantaneous power theory, it gives positive andnegative sequence current detection methods. Then it has analysis on direct andindirect current control mode, and proposes the control algorithm based on thethree-phase unbalance for the actual three-phase unbalanced load. In the end, a blockdiagram of the control system is given.(4) By MATLAB/SIMULINK based simulations of dynamic compensation fornew type electric arc furnace power system, the feasibility of the proposed system and the effectiveness of the STATCOM control method are verified. This simulation studymainly includes reactive power compensation under different load and impact load,the compensations for phase unbalance of the system. And then built a simpleexperiment platform, have an experimental analysis on the part of the hardwarecircuitry. The results from the simulation and experiment indicate that the newelectric arc furnace power system can solve the voltage fluctuations and flickerproblems brought by electric arc furnace. So it has a great practical significance toproject.