New strategy of control at low flicker level for DC electrical arc furnace converter

Low frequency conducted disturbances are usually induced by AC arc furnaces supplies: harmonic currents and flicker. That is why modern installations use a DC supply, less pollutant and sparing of electrodes. However, this process is not sufficient to reduce flicker during the melting sequence. On the basis of this problem, a structure of a modified bridge rectifier operating in a natural switching mode, has been studied and simulated. This converter allows a simultaneous control of the DC current and reactive power to the point common of coupling without using a Static Var Compensator. A large reduction of flicker is thus obtained at low cost. Moreover, operating at constant power is possible without overloading the semiconductors, the transformer and upstream network.<
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