Abstract: A method of controlling a regulating transformer with a settable translation ratio, switchable between a first and second AC-mains includes the following operations: detecting phasor data of phasors of the first and/or second AC-mains; determining an equivalent circuit diagram with equivalent circuit diagram parameters for the first AC-mains; determining a load model with load model parameters for the second AC-mains; determining the equivalent circuit diagram parameters and the load model parameters from the phasor data; and when switching over to a desired translation ratio is to take place: predicting a working point of the second AC-mains for the desired translation ratio; checking a stability criterion in the second AC-mains for the predicted working point; and switching over to the desired translation ratio is carried out upon the stability criterion being fulfilled, but otherwise not switching over to the desired translation ratio.

Abstract: A method of controlling a regulating transformer with a settable translation ratio, switchable between a first and second AC-mains includes the following operations: detecting phasor data of phasors of the first and/or second AC-mains; determining an equivalent circuit diagram with equivalent circuit diagram parameters for the first AC-mains; determining a load model with load model parameters for the second AC-mains; determining the equivalent circuit diagram parameters and the load model parameters from the phasor data; and when switching over to a desired translation ratio is to take place: predicting a working point of the second AC-mains for the desired translation ratio; checking a stability criterion in the second AC-mains for the predicted working point; and switching over to the desired translation ratio is carried out upon the stability criterion being fulfilled, but otherwise not switching over to the desired translation ratio.

Abstract: The invention relates to a device (1) and a method for controlling the stability of a local network (3). The local network (3) comprises a plurality of outgoing circuits (41, 42, . . . , 4M,), each having at least one load (5) and/or at least one decentralized energy generation system (6). Said device is provided with an on-load tap-changer (14) for adjusting an output voltage of the local network transformer (10). The device is characterized in that a unit (16) for measuring current, connected to at least one of the plurality of outgoing circuits (41, 42, . . . , 4M,), and a unit (18) for measuring voltage, connected to a busbar (8) of the local network (3), are arranged in a transformer housing (20).

Abstract: Disclosed is a device and method for reducing network feedback during operation of an electric-arc furnace (10). The electric-arc furnace (10) has three lines (7) with one electrode (4) each. A sensor (15) for measuring the currently flowing current and a sensor (16) for measuring the currently applied voltage are provided in each line. A control and regulating unit (30) calculates an electrical actual value (Eist1, Eist2, Eist3). A semiconductor tap changer (20) is assigned to the furnace transformer (6) such that, by suitably selecting three target winding taps (TSOLL1, TSOLL2, TSOLL3) of a primary side (P) of the furnace transformer (6), a target current (IS1, IS2, IS3) is adjustable in each line (7).

Abstract: The invention relates to a device (1) and a method for controlling the stability of a local network (3). The local network (3) comprises a plurality of outgoing circuits (41, 42, . . . , 4M), each having at least one load (5) and/or at least one decentralised energy generation system (6). Said device is provided with an on-load tap-changer (14) for adjusting an output voltage of the local network transformer (10). The device is characterised in that a unit (16) for measuring current, connected to at least one of the plurality of outgoing circuits (41, 42, . . . , 4M), and a unit (18) for measuring voltage, connected to a busbar (8) of the local network (3), are arranged in a transformer housing (20).

Abstract: Disclosed are an apparatus and method for process-based power regulation of an electric arc furnace (10). A plurality of sensor types (15, 16, 17) detect presently active operating parameters of the electric arc furnace (10) in dependence on time. From the measured values, a control and regulating unit (30) determines the necessity of whether to switch other winding taps (TS1 . . . TSN) of the primary side (6P) of the furnace transformer (6) by a semiconductor tap changer (20) in order to effect a modified electrical power to prevent thermal and/or mechanical damages to the electric arc furnace (10).

Abstract: Disclosed is a device and method for reducing network feedback during operation of an electric-arc furnace (10). The electric-arc furnace (10) has three lines (7) with one electrode (4) each. A sensor (15) for measuring the currently flowing current and a sensor (16) for measuring the currently applied voltage are provided in each line. A control and regulating unit (30) calculates an electrical actual value (Eist1, Eist2, Eist3). A semiconductor tap changer (20) is assigned to the furnace transformer (6) such that, by suitably selecting three target winding taps (TSOLL1, TSOLL2, TSOLL3) of a primary side (P) of the furnace transformer (6), a target current (IS1, IS2, IS3) is adjustable in each line (7).

Abstract: Disclosed is a device and a method for regulating an electric arc furnace (10) in the initial phase of a smelting process. A sensor (16) for measuring the present voltage and a sensor (15) for measuring the presently flowing current are provided in each line (7) of the electric arc furnace (10). The actual impedance (Zist) is time-dependently calculated by a control and regulating unit (30). An on-load tap changer (20) that is constructed as a semiconductor tap changer, is assigned to a furnace transformer (6) with a primary side (6P) and a secondary side (6S). The semiconductor tap changer (20) realizes a cycle time of a few milliseconds.