US3015059A - Stepless compensation of reactive current - Google Patents

Stepless compensation of reactive current Download PDF

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Publication number
US3015059A
US3015059A US820527A US82052759A US3015059A US 3015059 A US3015059 A US 3015059A US 820527 A US820527 A US 820527A US 82052759 A US82052759 A US 82052759A US 3015059 A US3015059 A US 3015059A
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Prior art keywords
current
winding
reactive current
load
control
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Expired - Lifetime
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US820527A
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English (en)
Inventor
Sangl Michael
Elischer Werner
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P Gossen and Co GmbH
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P Gossen and Co GmbH
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F29/00—Variable transformers or inductances not covered by group H01F21/00
    • H01F29/14—Variable transformers or inductances not covered by group H01F21/00 with variable magnetic bias
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F29/00—Variable transformers or inductances not covered by group H01F21/00
    • H01F29/14—Variable transformers or inductances not covered by group H01F21/00 with variable magnetic bias
    • H01F2029/143—Variable transformers or inductances not covered by group H01F21/00 with variable magnetic bias with control winding for generating magnetic bias
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Definitions

  • the invention pertains to a device for the stepless and, particularly, automatic compensation of a continuously changing inductive or capacitive reactive current by a controllable reactive load.
  • Inductive or capacitive reactive currents occur in various electric installations owing to the specific characteristics of the operation involved. This is the case, for example, in an induction melting furnace, where the material to be melted is inside a winding carrying alterhating current.
  • the inductive reactance of this winding is subject to considerable fluctuation in the melting of ferromagnetic, paramagnetic, and diamagnctic substances because of the changes of the ohmic resistance and the magnetic conditions within the material being melted.
  • the continuously varying inductive current of the furnace must be continuously compensated by capacitances in parallel. Up to the present time the effective parallel capacitance has had to be adapted to the condition of the melt by connecting or disconnecting capacitances by means of contactors, by hand, or by automatic switchgear.
  • the reactive current compensation of the invention consists entirely of stationary and sturdy parts that are not subject to any wear.
  • the expensive contactors that are othervn'se required are eliminated completely, and the entire capacitance, which heretofore has been subdivided into several units, may be combined into a fixed unit.
  • the arrangement of the invention makes it possible to compensate the reactive current continuously and in such a way that there is a small capacitive component in the line.
  • FIG. 1 is a basic circuit diagram of the invention.
  • FIG. 2 illustrates the construction of the transductor.
  • FIGS. 3a, 3b and 4 are diagrams explanatory of the operation of the invention.
  • FIG. 5 is a diagram of an automatic compensating ar rangement according to the invention.
  • controllable inductance is embodied in the load winding 1, connected in parallel with the furnace winding 2. In parallel with the latter there is the capacitance 3.
  • These circuit elements are connected to the A.C. source 5-, a medium-frequency generator for, say, 10 kilocycles, via the lines 4 and 4
  • the capacitance 3 is dimensioned so as to compensate the maximum inductive current of the furnace.
  • the mechanical construction of the transductor consisting of the two parts T and T is shown in FIG. 2. It consists of the two adjacent iron cores 6 and 7, which are designed as continuous-strip toroidal cores, the load winding 8 and 9, and the control winding 10, which is wound around the two other legs of cores 6 and 7 for both.
  • the load winding consists of two parts, wound in opposite directions, and connected in parallel. As the same A.C. voltage is impressed on both parts of the load winding, the actions of the induction fluxes flowing in the center legs of the core upon the control winding 10 cancel out.
  • FIG. 3a To explain the mode of operation two idealized magnetization curves for the two transductors T and T respectively, are shown in FIG. 3a.
  • the D.-C. biasing should be chosen so that when there is no A.C. voltage applied, core 6 is saturated negatively at point P and core 7 saturated positively at point P When A.C. voltage is impressed across the load winding, an additional alternating flux is superposed on the constant biasing D.-C. fiux in each transductor.
  • the cores of the transductors and the load windings 8 and 9 are so dimensioned with respect to the A.C. voltage, that when no bias magnetization is present, they are not saturated by the A.C. voltage.
  • the current i can only rise to the value of the control current in the load winding of T As the voltage continues to rise, the core of T emerges from the region of saturation, because the saturating action of the control voltage is exact- 1y balanced out in this case. Because of the very high inductance of the load winding along the steep portion of the demagnetization characteristic, the current i remains constant to begin with, until the field has again been displaced so far into the negative region toward the end of the subsequent negative half-wave that the lower break in the curve is reached.
  • the polarization (biasing) is so chosen that the currenta time area of the compensation pulse, together with that of the half-wave of the inductive reactive current, equals the current-time area of the capacitive half-wave.
  • the circuit for measuring 1 sin qt consists of the current transformer 11, which is connected on its secondary side with another current transformer 12, the rectifiers 13, 14, 15, and 16, the condenser 17, and the two condensers 1S and 19 connected in series.
  • a rectifier 20 as well as the control windingsof 'a magnetic amplifier 21 are connected to the output end of this'I-sin g measuring circuit, formed by the terminalsofthe'series'circuits 18 and 19.
  • Another rectifier 22 is connected in the line to these control windings;
  • the rectifiers 13-16 constitute a remote-controlled switch, being opened and closed by the voltage across the lines 4 and 4;. Either rectifiers 13 and 14 are opened and rectifiers and 16 closed, or vice versa, .iepending'upon theinstantaueous polarities.
  • control voltage opens up two different current paths for the secondary current in transformer 12. But as any change in these current paths also changes the polarity of the secondary current in the current transformer 12, a pulsating DC. current flows through the elements connected to the output ends of the I -sin measuring circuit.
  • the phase of the control current produced by the voltage across the lines 4 and 4 is displaced through by the capacitor 17 and by the capacitors 18 and 19 that act in parallel in this case.
  • the polarity of the pulsating D.-C. current at the output ends of the I-sin measuring circuit just described depends upon whether the reactive current flowing through the lines 4 and 4 is capacitive or inductive.
  • Rectifiers 20 and 22 act so as to allow a control current to flow through the control windings of the transductor (magnetic amplifier) 21 only when this reactive current is capacitive.
  • the control winding 10 of the regulating reactor of the invention whose output windings 8 and 9 are connected in parallel with the furnace winding 2, serves as a load for the'magnetic amplifier 21, being connected to the latter through the rectifier bridge 23, which contains a smoothing capacitor, not shown.
  • the reactive current compensator regulates the line current to a fixed reactive current I sin 4) that corresponds to the given direct current in one case, while in the other it regulates the line current to any desired power factor cos 4:.
  • This supplementary winding is required whenever a power factor is wanted on the line that differs from unity.
  • Small reactive currents can also be controlled by employing a so-called inductance-controlled regulating reactor, in which the working point is shifted back and forth by the biasing control parameter within the steeper and not yet fully saturated regions of the magnetization characteristic curve.
  • This arrangement has the advantage of being particularly free of upper harmonics.
  • core material formed of ferrite is advisable instead of the cores 6 and 7, which are preferably made of thin iron strip in the present case.
  • Apparatus for continuously compensating for reactive current in an alternating current line connected to an inductive load comprising circuit means for producing a direct currentwhich is a measure of. the reactive component of the line current, said means including a rectifier switching circuit, an input transformer connected to the input of' said rectifier circuit, a current transformer connecting said alternating current line to the primary winding of the input transformer, acapacitor connecting one side of said line to a midpoint of the secondary of the input transformer, and means for connecting the midpoint of the output of said rectifier circuit to the other side of the alternating current line, capacitor means connected in parallel with said load, said capacitor means having a greater magnitude than that required to compensate for the inductive load, a magnetic amplifier, said magnetic amplifier including two contiguous ring cores, a control winding Wound around both cores, and a load winding connected across said line and said control winding, said load winding comprising two coils connected in parallel and wound on each of said cores, respectively, to produce op- 10 posing magnetic fields in
  • Apparatus according to claim 1 including a second magnetic amplifier having load windings and a control Winding, a rectifier connecting said last-mentioned control Winding to the output of said rectifier circuit, and a second rectifier connected in series with the load windings of the second magnetic amplifier across the line, the output of said second rectifier being connected to the control winding of the first-mentioned magnetic amplifier.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Electrical Variables (AREA)
US820527A 1958-09-06 1959-06-15 Stepless compensation of reactive current Expired - Lifetime US3015059A (en)

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Application Number Priority Date Filing Date Title
DE19581069278D DE1069278B (enrdf_load_stackoverflow) 1958-09-06 1958-09-06

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US3015059A true US3015059A (en) 1961-12-26

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987001505A1 (en) * 1985-09-02 1987-03-12 Hasler Ag Inductive, electrically-controllable component
EP0660214A3 (en) * 1993-12-24 1996-09-25 Icar Spa Power factor correction / filtering kit.
EP0748471A4 (en) * 1994-03-04 1998-06-17 Marelco Power Systems Inc AN ELECTRICALLY CONTROLLED INDUCTION DEVICE
US10910150B2 (en) * 2015-11-30 2021-02-02 Intel Corporation Reconfigurable coupled inductor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1199400B (de) * 1963-12-17 1965-08-26 Pintsch Bamag Ag Schaltungsanordnung zum Betrieb von Leuchtstofflampen an fremdgesteuerten Halbleiter-Wechselrichtern

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1227302A (en) * 1915-07-08 1917-05-22 Gen Electric Means for controlling alternating currents.
US1836886A (en) * 1930-04-29 1931-12-15 Gen Electric Electrical regulator and regulating system
US2421786A (en) * 1944-07-28 1947-06-10 Salle Nat Bank Circuit control apparatus
US2793338A (en) * 1955-12-22 1957-05-21 Cline Electric Mfg Co System for controlling induction motors by saturable reactors and coordinately controlled resistors

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1019410B (de) * 1956-06-20 1957-11-14 Bbc Brown Boveri & Cie Verfahren und Vorrichtung zur Kompensation der Blindleistung eines induktiven Stromverbrauchers, vorzugsweise eines Induktionsofens

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1227302A (en) * 1915-07-08 1917-05-22 Gen Electric Means for controlling alternating currents.
US1836886A (en) * 1930-04-29 1931-12-15 Gen Electric Electrical regulator and regulating system
US2421786A (en) * 1944-07-28 1947-06-10 Salle Nat Bank Circuit control apparatus
US2793338A (en) * 1955-12-22 1957-05-21 Cline Electric Mfg Co System for controlling induction motors by saturable reactors and coordinately controlled resistors

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987001505A1 (en) * 1985-09-02 1987-03-12 Hasler Ag Inductive, electrically-controllable component
EP0660214A3 (en) * 1993-12-24 1996-09-25 Icar Spa Power factor correction / filtering kit.
EP0748471A4 (en) * 1994-03-04 1998-06-17 Marelco Power Systems Inc AN ELECTRICALLY CONTROLLED INDUCTION DEVICE
US10910150B2 (en) * 2015-11-30 2021-02-02 Intel Corporation Reconfigurable coupled inductor

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DE1069278B (enrdf_load_stackoverflow) 1959-11-19

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