Series control of electric ARC furnaces
AssigneeGeneral Electric Company
InventorEinar V. Larsen
Life of this patent
Estimating the term…
Abstract
A circuit and method for regulating power supplied on a network which provides power to an electric arc furnace or other highly variable load. The circuit includes at least a first inverter connected in series with the arc furnace transformer, and in shunt with the power supply. The circuit and method provide an effective, low cost technique for controlling network power.
Claims28
A method for providing a controlled AC voltage to a fluctuating load, comprising the steps of:
- providing a first AC voltage via a main transformer, the main transformer being connected in series with a series transformer;
- providing a first inverter connected in series between the main transformer and the fluctuating load, the first inverter connected to a second inverter via a DC link;
- generating control signals in a programmed microprocessor, based on signal inputs indicative of one or more of:
- a supply voltage,
- a DC voltage across the DC link, and
- a load current;
- and,
- providing the control signals to the first inverter and the second inverter based upon the signal inputs;
- wherein the first inverter is controlled to regulate an overall impedance presented to the main transformer.
A circuit for regulating power in a power system having an erratic load which is supplied from a power supply, comprising:
- a main transformer which receives electric current from the power supply (12);
- a series transformer connected in series with the main transformer;
- a first inverter connected in series with the power supply to regulate an effective impedance of the load;
- a second inverter connected, via the main transformer, in shunt to the power supply to regulate a DC link of the first inverter;
- and
- a microprocessor based controller, which receives signal inputs indicative of one or more of:
- a supply voltage,
- a DC voltage across the DC link, and
- a load current;
- and,
- based, at least in part, upon the signal inputs, the microprocessor based controller outputs control signals to the first inverter and the second inverter;
- wherein the microprocessor based controller is programmed to
- enable the regulation of an active power portion of the electric current to maintain an operator set-point for average value and,
- to minimize the electric current fluctuations within a predetermined bandwidth.
A method for regulating an AC voltage provided from a power supply to a fluctuating load, comprising the steps of:
- providing a main transformer which receives electric current from the power supply;
- providing a series transformer connected in series with the main transformer;
- providing at least a first inverter connected in series with the power supply;
- providing at least a second inverter connected, via main transformer, in shunt with the power supply;
- and
- providing a control circuit, which receives signal inputs indicative of one or more of:
- a supply voltage,
- a DC voltage across the DC link, and
- a load current;
- and,
- providing control signals from the control circuit to at least the first inverter and the second inverter to control the first and second inverters to regulate an overall impedance presented to the power supply.
A circuit for regulating an AC voltage provided from a power supply to a fluctuating load, comprising:
- a main transformer which receives electric current from the power supply;
- a series transformer connected in series with the main transformer;
- a first inverter connected in series with the power supply;
- a second inverter connected, via main transformer, in shunt with the power supply, and connected to regulate a DC link of the first inverter;
- and
- a control circuit connected to the first and second inverters, which receives signal inputs indicative of one or more of:
- a supply voltage,
- a DC voltage across the DC link, and
- a load current;
- and,
- based, at least in part, upon the signal inputs, the control circuit outputs control signals to the first inverter and the second inverter;
- wherein the control circuit controls the first and second inverters to regulate an overall impedance presented to the power supply.
Dependencies are inferred from the claim text.