Siemens Aktiengesellschaft

Siemens Energy Global Gmbh & Co. Kg

Wolfgang Hörger

Martin Pieschel

Hans-Joachim Knaak

Arno Döbbeler

Reinhard Hoffmann

Wolfgang Meusel

Peter Eckert

Karsten Rechenberg

Jonas Pinkwart

In a power supply system for a three-phase arc furnace (), comprising at least one furnace transformer (), the furnace transformer () is connected on the secondary side to the three-phase arc furnace (). On the primary side, the furnace transformer () is connected to a three-phase supply mains () through an indirect converter (). The indirect converter () comprises at least one rectifier () on the mains side, at least one inverter () on the transformer side, and an intermediate circuit () between the rectifier () and the inverter (). Each phase of the three-phase supply mains () is connected to the intermediate circuit () through two converter elements () of the rectifier () in each case. Each primary-side phase of the furnace transformer () is connected to the intermediate circuit () through two converter elements () of the inverter () in each case.

Power supply system for a polyphase arc furnace with an indirect converter between a mains connection and a furnace transformer

A multilevel converter has a plurality of converter strands, which are connected to the phases of a three-phase-network in a star or delta connection. From phase voltage values and phase current values, an active component characteristic of the overall active current and two asymmetrical components characteristic of a distribution of the overall flowing active and reactive currents are determined. The active and the two asymmetrical components are each filtered and multiplied with the phase voltage values and the two filtered asymmetrical components. The multiplied values are then weighed and added to the phase current values. From the asymmetrical components and the phase voltage values, a zero current is determined and added to the phase current values such that it symmetrizes a potential asymmetrical active current flow that would occur without the zero current. From the modified phase current values, a control state for the converter strands is determined.

Multilevel converter as reactive power compensator having active

A static VAR compensator has several parallel compensation components (K&#x2013;K). To connect the static VAR compensator to an operating voltage (U) the compensation components (K&#x2013;K) are first successively connected to the operating voltage (U) by a control unit (CU) via a series resistor (R). The compensation components (K&#x2013;K) are only connected to the operating voltage (U) without series resistance once the aforementioned connection has been completed.

Connection method for a static VAR compensator

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Hausen, Germany

Wolfgang Hörger