WO2011086429A1 - Système de correction du facteur de puissance secondaire à haute tension, et procédé pour fours à alimentation alternative - Google Patents

Système de correction du facteur de puissance secondaire à haute tension, et procédé pour fours à alimentation alternative Download PDF

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Publication number
WO2011086429A1
WO2011086429A1 PCT/IB2010/054835 IB2010054835W WO2011086429A1 WO 2011086429 A1 WO2011086429 A1 WO 2011086429A1 IB 2010054835 W IB2010054835 W IB 2010054835W WO 2011086429 A1 WO2011086429 A1 WO 2011086429A1
Authority
WO
WIPO (PCT)
Prior art keywords
voltage
furnace
transformer
secondary winding
power supply
Prior art date
Application number
PCT/IB2010/054835
Other languages
English (en)
Inventor
Hendrik Willem Greyling
Frederik Petrus Greyling
Original Assignee
Hendrik Willem Greyling
Frederik Petrus Greyling
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hendrik Willem Greyling, Frederik Petrus Greyling filed Critical Hendrik Willem Greyling
Priority to AU2010291894A priority Critical patent/AU2010291894B2/en
Priority to ZA2011/02396A priority patent/ZA201102396B/en
Publication of WO2011086429A1 publication Critical patent/WO2011086429A1/fr

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/144—Power supplies specially adapted for heating by electric discharge; Automatic control of power, e.g. by positioning of electrodes
    • H05B7/148—Automatic control of power
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • This invention relates to an electrically operable furnace and more particularly to an electrical power supply for an AC furnace and a method of power factor correction.
  • a furnace power supply system comprising:
  • At least one furnace power supply voltage step-down transformer for stepping down a first voltage to a second voltage
  • At least one voltage step-up transformer a primary winding of which is connected to the secondary winding of the voltage step-down transformer, to step up the second voltage to a third voltage
  • the power factor correction component may comprise a capacitor.
  • a switch may be provided between the secondary winding of the step- up transformer and the at least one power factor correction reactive component.
  • the first voltage may be higher than the third voltage, which is higher than the second voltage.
  • the first voltage may be between 1 1 kV and 33kV
  • the second voltage may be between 200V and 600V
  • the third voltage may be between 6.6kV and 22kV.
  • connection between the secondary winding of the at least one step-down transformer and the at least one electrode may comprise high current furnace bus tubes.
  • connection between the secondary winding of the at least one step-up transformer and the at least one power factor correction reactive component may comprise high voltage cable.
  • an AC furnace comprising a furnace power supply system as herein defined and/or described.
  • a method of power factor correction in an AC furnace comprising the steps of: - on a secondary side of a power supply step-down transformer for stepping down a first supply voltage to a second lower voltage connected to at least one electrode of the furnace, stepping up the second lower voltage to a third voltage; and
  • the reactive component may comprise a capacitor.
  • figure 1 is a basic circuit diagram of a furnace power supply system according to the invention.
  • figure 2 is a more detailed diagram of a first embodiment of the system
  • figure 3 is a more detailed diagram of a second embodiment of the system; and is a vector diagram illustrating an improvement in active power delivered to the furnace and hence an improvement in capacity of the furnace.
  • a furnace power supply system according to the invention for an electrically operable AC furnace is generally designated by the reference numeral 10 in the figures.
  • the furnace power supply system 10 comprises at least one furnace power supply step-down transformer 1 2 for stepping down a first voltage V1 to a second voltage V2.
  • a secondary winding 1 2.2 of the step down transformer 1 2 is connectable to at least one electrode 1 4 of the furnace 1 6,
  • the system 10 further comprises at least one voltage step-up transformer 1 8.
  • a primary winding 1 8.1 of the voltage step-up transformer is connected to the secondary winding 1 2.2 of the voltage step-down transformer 1 2, to step up the second voltage V2 to a third voltage V3.
  • At least one power factor correction reactive component in the form of a capacitor 20 is connected to the secondary winding 1 8.2 of the step-up transformer 1 8.
  • the furnace 16 comprises three electrodes 14.1, 14.2 and 14.3.
  • Three similar furnace power supply step-down transformers 112.1 to 112.3 are provided to step down a first and high supply voltage V1 (typically 11kV to 33kV) to a second and lower furnace operating voltage V2 (typically 200V to 600V).
  • Electrodes 14.1 and 14.2 are connected in known manner by high current furnace bus tubes 22 to the secondary winding 12.2 of the step-down transformer 112.1.
  • electrodes 14.2 and 14.3 are connected to the secondary winding 12.2 of the transformer 112.2 and electrodes 14.3 and 14.1 to the secondary winding of the transformer 112.3.
  • a primary winding 18.1 of a first voltage step-up transformer 118.1 is connected across the secondary winding 12.2 of step-down transformer 112.1 to step up the second voltage to a third voltage V3 (typically 6.6kV to 22kV).
  • a power factor correction capacitor arrangement 20.1 forming part of a high voltage capacitor bank 120 is connected by high voltage cables 24 and optionally, but preferably, a high voltage switch arrangement 26, to the secondary winding 18.2 of first voltage step-up transformer 118.1.
  • the switch arrangement 26 which may be in the form of a circuit breaker or contactor, in use, serves selectively to isolate the capacitor arrangement 20.1 or bank 120 from the load in the form of the electrode furnace 1 6.
  • power factor correction capacitor arrangements 20.2 and 20.3 are connected to the secondary windings 1 8.2 of second and third voltage step-up transformers 1 1 8.2 and 1 1 8.3, respectively.
  • the embodiment in figure 3 is similar to the embodiment of figure 2, except that the furnace comprises six electrodes 14.1 to 1 4.6, of which electrodes 14.1 and 1 4.2, 1 4.3 and 14.4, and 14.5 and 1 4.6 are connected to the secondary windings of the voltage step-down transformers 1 1 8.1 to 1 1 8.3, respectively, as shown in figure 3.
  • the vector diagram in figure 4 illustrates that for an apparent power S for the furnace step-down transformer 1 2 (shown in figure 1 ) of say 63 MVA, with a prior art power factor ⁇ 1 of between 70% and 85% as referred to in the introduction of this specification, there is an active power component P1 of about 50.3 MW and a reactive power component of Q1 .
  • the aforementioned capacitor arrangements reduce the reactive power component as seen by the transformer 1 2 to Q2, thereby improving the power factor to ⁇ 2 of about 90%, so that for the same apparent power S, additional active power (up from P1 to P2 of about 56.7 MW) is supplied to the furnace 1 6, thus increasing the production capacity of the furnace.
  • step-up transformers The function of the step-up transformers is to step up the second voltage V2 to a substantially higher third voltage V3, to enable the use of high-voltage switchgear, cables and capacitor banks.
  • standard high-voltage capacitor banks designed to improve the power factor, as hereinbefore described may be connected to the step-up transformers 1 1 8.1 to 1 1 8.3, thus allowing additional power to be supplied to the load 1 6 from existing or conventional furnace power supply step-down transformers 1 1 2.1 to 1 1 2.3.
  • Standard and proven reliable high voltage capacitor banks 1 20 may be used for the power factor correction. Because conventional high voltage cables 24 are used between the secondary winding 1 8.2 of the step-up transformers 1 1 8.1 to 1 1 8.3 and the power correction capacitor bank 1 20, the capacitor bank 1 20 may be located remote from the step-up transformers 1 1 8.1 to 1 1 8.3 and hence outside the furnace building (not shown) .
  • the high voltage switch 26 allows for disconnection of the capacitor bank 1 20 from the furnace step-down transformers 1 1 2.1 to 1 1 2.3, ensuring that the secondary power factor correction system does not affect furnace availability.
  • the capacitor bank 1 20 may be switched out during switching operation of the furnace transformers 1 1 2.1 to 1 1 2.3. Only after switching on of the furnace power supply transformers, is the capacitor bank 1 20 connected. Switching surges and power system disturbances may thereby be avoided.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

L'invention concerne un système d'alimentation électrique pour fours (10), comprenant au moins un transformateur abaisseur de tension d'alimentation électrique pour four (12) qui abaisse une première tension V1 à une deuxième tension V2. Un bobinage secondaire (12.2) du transformateur abaisseur de tension (12) peut être connecté à au moins une électrode (14) du four (16). Le système d'alimentation électrique comprend au moins un transformateur élévateur de tension (18) dont un bobinage primaire (18.1) est raccordé au bobinage secondaire (12.2) du transformateur abaisseur de tension (12), afin de relever la deuxième tension V2 à une troisième tension V3. Au moins un composant réactif de correction du facteur de puissance (20) est connecté au bobinage secondaire (18.2) du transformateur élévateur de tension.
PCT/IB2010/054835 2010-01-14 2010-10-26 Système de correction du facteur de puissance secondaire à haute tension, et procédé pour fours à alimentation alternative WO2011086429A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2010291894A AU2010291894B2 (en) 2010-01-14 2010-10-26 High voltage secondary power factor correction system and method for AC furnaces
ZA2011/02396A ZA201102396B (en) 2010-01-14 2011-03-31 High-voltage secondary power factor correction system and method for ac furnaces

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA2010/00273 2010-01-14
ZA201000273 2010-01-14

Publications (1)

Publication Number Publication Date
WO2011086429A1 true WO2011086429A1 (fr) 2011-07-21

Family

ID=43465343

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2010/054835 WO2011086429A1 (fr) 2010-01-14 2010-10-26 Système de correction du facteur de puissance secondaire à haute tension, et procédé pour fours à alimentation alternative

Country Status (3)

Country Link
AU (1) AU2010291894B2 (fr)
WO (1) WO2011086429A1 (fr)
ZA (1) ZA201102396B (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB630894A (en) * 1947-01-08 1949-10-24 William Beardmore & Co Ltd Improvements in or relating to regulator gear for electric arc furnaces
FR1326200A (fr) * 1962-04-06 1963-05-03 Secheron Atel Installation de réglage automatique d'un four à arc triphasé
FR2926182A1 (fr) * 2008-01-08 2009-07-10 Toulouse Inst Nat Polytech Dispositif d'alimentation electronique de puissance pour four a arc alimente en courant alternatif.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB630894A (en) * 1947-01-08 1949-10-24 William Beardmore & Co Ltd Improvements in or relating to regulator gear for electric arc furnaces
FR1326200A (fr) * 1962-04-06 1963-05-03 Secheron Atel Installation de réglage automatique d'un four à arc triphasé
FR2926182A1 (fr) * 2008-01-08 2009-07-10 Toulouse Inst Nat Polytech Dispositif d'alimentation electronique de puissance pour four a arc alimente en courant alternatif.

Also Published As

Publication number Publication date
ZA201102396B (en) 2012-12-27
AU2010291894B2 (en) 2015-08-13
AU2010291894A1 (en) 2011-07-28

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