Siemens Aktiengesellschaft

Arno Doebbeler

Werner Hartmann

Thomas Matschullat

Martin Pieschel

Hans-Joachim Knaak

Martin Hergt

Detlef Rieger

Wolfgang Meusel

Wolfgang Hoerger

Jonas Pinkwart

Juergen Rupp

Ralf Engels

An apparatus for regulating an electric arc furnace connected to a power supply system with at least one system phase that applies an AC voltage to a furnace electrode and an arc current for melting. A control loop device includes an electrical converter designed for negative feedback of an amplitude and/or frequency of the AC voltage to produce an amplitude and/or frequency of the arc current. The converter includes an input port having a system power supply connected thereto, and an output port having a melting furnace power supply and a primary circuit of a first transformer connected thereto, wherein a secondary circuit of the first transformer is connected to the arc furnace electrode. A primary coil of a second transformer is connected in parallel with the converter input port, and a secondary coil of the first transformer is connected in series with a secondary coil of the second transformer.

Apparatus and method for dynamically adjusting an electric arc furnace

A non-linear load in the form of an arc furnace with an upstream furnace transformer is supplied with electric power from a power supply device with a plurality of converter units. The converter units have a plurality of main modules with inputs connected to a respective phase of a three-phase grid. The converter units have a common star point between the main modules and the primary side of the furnace transformer. Each main module has a series circuit with a coupling inductance and a plurality of submodules. The submodules have a bridge circuit with four self-commutated semiconductor switches and a bridge path with a storage capacitor between input and output. The semiconductor switches of the submodules can each be switched independently of the semiconductor switches of the other submodules of the same main module and of the other main modules.

Power supply for a non-linear load with multilevel matrix converters

Flicker values to be expected may be determined and achieve a high probability from suitable state and operating variables which are acquired during the first minutes in the initial smelting phase. In this way, flicker can effectively be reduced and kept below predefined limiting values. This is in particular suitable during steel production using electric arc furnaces.

Flicker reduction in electric arc furnaces by means of flicker prediction from the state determination in the initial phase of the smelting process

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Herzogenaurach, Germany

Arno Doebbeler