Electric Arc Furnace Voltage Fluctuation And Flicker Suppression Strategy Based On Virtual Synchronous Generator Control

Electric arc furnace is an important steel-making equipment.Its working principle is to melt scrap steel by arc generated between graphite electrodes and scrap steel.Frequent short-circuit between electrodes and scrap steel occurs during the contact process,which generates a large impact current,causes the rapid fluctuation of reactive power,causes the rapid fluctuation and flicker of voltage on the side of power grid,and affects the stable operation of other devices.Therefore,effective suppression of voltage fluctuation and flicker caused by electric arc furnace on the grid side has important academic value and engineering significance.Currently,cascade H-bridge static synchronous compensator based on vector control is often used to compensate the reactive power of electric arc furnace when it is connected to the power network to suppress voltage fluctuation and flicker,but the response speed is relatively slow,and the effect of improving the three-phase voltage unbalance caused by asymmetric voltage drops in the power network is not good.In order to overcome these shortcomings,an improved control method of virtual synchronous generator is presented,which is applied to the static synchronization compensator.It greatly improves the suppression speed of voltage fluctuation and flicker,and effectively solves the problem of three-phase voltage unbalance.At the same time,vector controlled static synchronization compensator often uses coordinate transformation to solve the Phase-to-Phase capacitor voltage balancing between DC sides of cascade H-bridge,which is not applicable to the control method of virtual synchronous generator.A new method of Phase-to-Phase capacitor voltage balancing is designed in this paper.The average capacitance voltage of each phase is calculated and compared with the reference capacitance voltage.The phase offset is superimposed on the phase value output of the virtual synchronous generator to balance the phase capacitance voltage of the DC side of the static synchronization compensator.Finally,a large number of simulation comparisons and analyses verify that the improved virtual synchronous generator control strategy has a good effect on fast suppression of voltage fluctuation and flicker of electric arc furnace,and the control strategy has been applied to the electric arc furnace system of a special steel in Hebei,and good practical results have been obtained.