WO2007035110A1 - Dispositif autotransformateur à entrefer magnétique - Google Patents

Dispositif autotransformateur à entrefer magnétique Download PDF

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Publication number
WO2007035110A1
WO2007035110A1 PCT/NO2006/000327 NO2006000327W WO2007035110A1 WO 2007035110 A1 WO2007035110 A1 WO 2007035110A1 NO 2006000327 W NO2006000327 W NO 2006000327W WO 2007035110 A1 WO2007035110 A1 WO 2007035110A1
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WO
WIPO (PCT)
Prior art keywords
winding
autotransformer
magnetic
parallel
core
Prior art date
Application number
PCT/NO2006/000327
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English (en)
Other versions
WO2007035110A9 (fr
Inventor
Kjell Hystad
Original Assignee
Magtech As
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 Magtech As filed Critical Magtech As
Publication of WO2007035110A1 publication Critical patent/WO2007035110A1/fr
Publication of WO2007035110A9 publication Critical patent/WO2007035110A9/fr

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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/12—Regulating voltage or current wherein the variable actually regulated by the final control device is ac
    • G05F1/32—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using magnetic devices having a controllable degree of saturation as final control devices
    • G05F1/34—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using magnetic devices having a controllable degree of saturation as final control devices combined with discharge tubes or semiconductor devices
    • G05F1/38—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using magnetic devices having a controllable degree of saturation as final control devices combined with discharge tubes or semiconductor devices semiconductor devices only

Definitions

  • the present invention relates to methods and systems for voltage stabilization. More particularly, the invention relates to methods and systems that employ a variable inductance to compensate for voltage variations that may arise in power supply lines, and to reduce total harmonic distortion in the power supply.
  • Undersized lines for electric power transmission also referred to as "weak lines" have too small a conductor cross section in relation to the load requirements and a relatively high resistance. Excessive voltage drop will result from the losses caused by undersized conductors. The excessive voltage drop results in inadequate voltage levels for the electric power connected to the lines.
  • a transformer is a static unit which supplies an output voltage determined by the number of windings on the primary and secondary sides, i.e., the transformer ratio.
  • a fixed transformer ratio may result in a voltage that is too low, (i.e., an under- voltage) when the load is high, and a voltage that is too high, (i.e., an over- voltage condition) when the load is low. Because the load is dependent at all times on the highly variable requirements of individual electric power consumers, fixed ratio transformers are often inadequate to serve a dynamic load in weak lines. The low voltage level can be compensated for by increasing the voltage in steps at the transformer that is supplying the line.
  • the voltage level is controlled by means of a load tap changer on the transformer which is connected to the individual phase at the location where the voltage reaches an unacceptably low level.
  • Another approach comprises replacing existing lines with new lines having a larger cross section and correspondingly lower resistive losses.
  • a mechanically controlled variac i.e., a transformer with variable transformer ratio
  • a transformer with variable transformer ratio is used in connection with a transformer.
  • mechanically controlled variacs generally, are no longer used because the mechanical components required frequent service.
  • WO 2004/053615 describes a system for voltage stabilization of power lines.
  • One application of this system is illustrated in fig. 1, showing an autotransformer A (indicated with dashed lines) having a series winding 7, in series with the input voltage Uin and the output voltage Uout, and a parallel winding 4, parallel to the series winding 7.
  • the system further comprises a variable inductor B (indicated with dashed lines) which is connected to the autotransformer, and a control system to control the inductance of the variable inductor B.
  • the variable inductor B includes a magnetic core, a main winding 2 wound around a first axis, and a control winding 3 wound around a second axis orthogonal to the first axis.
  • a main winding 2 wound around a first axis
  • a control winding 3 wound around a second axis orthogonal to the first axis.
  • This voltage stabilization system automatically compensates for voltage variations in the power supply line to which it is connected.
  • the permeability control is performed using orthogonal fields and it is not performed by means of parallel fields which are added or subtracted.
  • the above mentioned system can be used for dynamic control of each phase voltage individually to correct for voltage drop.
  • Power Factor PF which is a measure for the phase difference between the voltage and the current of the system.
  • the PF is often referred to as cos ⁇ , and, though not always achievable, a cos ⁇ near 1 is desired in most electro technical equipment.
  • the object of the present invention is to provide a method and a system for voltage stabilization, employing a variable inductance to compensate for voltage variations that may arise in power supply lines, and where the above disadvantages are avoided.
  • Another object of the present invention is to provide a system has few and reliable components. Another object is to reduce the total weigh of the components in the total system.
  • the present invention relates to a system for voltage stabilization and reduction of total harmonic distortion in power transmission lines, for each phase comprising: an autotransformer with a series winding and a parallel winding, where the series winding is connected between an input voltage Uin and an output voltage Uout; a magnetic controllable inductor comprising a main winding wound around a core, and a control winding wound around the core, where the control winding is adapted for creating a magnetic field mainly orthogonal to the field created by the main winding, thereby controlling the inductance of the magnetic controllable inductor, and wherein: the parallel winding of the autotransformer is connected between the input voltage Uin and the main winding of the magnetic controllable inductor, and the main winding of the magnetic controllable inductor is connected between a parallel winding and a neutral point, where the other terminal of the main winding is connected to the neutral point, characterized in that: the system comprises a magnetizing inductance, which provides an increase in the magnetizing current of
  • the magnetizing inductance can be provided by a magnetic air gap in the core of the autotransformer and/or by separate inductor connected in parallel to the parallel winding of the autotransformer.
  • FIG. 1 illustrates a prior art system for voltage stabilization
  • Fig. 2 illustrates a first embodiment of the invention
  • Fig. 3 illustrates a second embodiment of the invention
  • Fig. 4a - 4d illustrates the autotransformer with its physical representation and the corresponding "ideal transformer” equivalent
  • Fig. 5a and 5b illustrates phase coordination diagrams of voltages and currents in fig. 1 - 3, and
  • Fig. 6 and 7 shows the physical construction of the autotransformer with or without the magnetic air gap.
  • Fig. 1 is briefly described in the introduction above, and shows one phase of a voltage stabilisation system comprising an autotransformer A with a series winding 7 and a parallel winding 4.
  • the system further comprises a magnetic controllable inductor B (MCI) comprising a main winding 2 and a control winding 3.
  • MCI magnetic controllable inductor B
  • the series winding 7 is connected between an input voltage Uin and an output voltage Uout.
  • the parallel winding 4 is connected between the input voltage Uin and the main winding 2 of the magnetic controllable inductor B.
  • the other terminal of the main winding 2 is connected to the neutral point.
  • the control winding 3 of the controllable inductor B is adapted for creating a magnetic field mainly orthogonal to the field created by the main winding 2, thereby controlling the inductance of the magnetic controllable inductor B.
  • the construction and the operation of the controllable inductor B is described in prior art and will not be described in detail here.
  • the current I M CI through the main winding 2 of the controllable inductor B in fig. 2 is equal to the current Ip through the parallel winding 4 of the autotransformer A.
  • the voltages and currents of the autotransformer are shown as a physical representation and its ideal equivalent in fig. 4a and 4b respectively.
  • the parallel current Ip is equal to the current Is of the series winding 7 divided to the transformer ratio n.
  • fig. 2 shows a first embodiment of the invention which solves the problems and disadvantages with the system shown in fig. 1, as described in the introduction above.
  • Equal or similar elements in fig. 2 have the same reference numbers as in fig. 1, and will not be described here in detail.
  • an additional inductor C is connected in parallel to the parallel winding 4 of the autotransformer A. Consequently, the current I MCI through the main winding 2 of the controllable inductor B in fig. 2 is equal to the current Ip through the parallel winding 4 plus the current Ic through the additional inductor C.
  • fig. 3 where second embodiment of the invention is shown, comprising an autotransformer A' and a magnetic controllable inductor B, which is as described above with the same reference numbers.
  • the main difference between fig. 1 and fig. 3 is that the autotransformer A' comprises a magnetic air gap, as will be described in detail below.
  • the current I MCI through the main winding 2 of the controllable inductor B is equal to the current Ip' through the parallel winding 4 of the autotransformer A'.
  • a “magnetic air gap” is a part of a core in a transformer comprising a non-magnetizable material, or a material with a high magnetic "resistance". Consequently, introducing a magnetic air gap in a transformer increases the reluctance (magnetic "resistance") in the flux path, hence increasing the current that is drawn from the power source.
  • the voltages and currents of the autotransformer in fig. 3 are shown as a physical representation in fig. 4a and 4b, and its ideal equivalent in fig. 4c and 4d respectively.
  • the magnetic air gap introduces an increased magnetizing current Im. Consequently, the primary current Ip' is equal to a magnetizing current Im plus the secondary current Is divided to the transformer ratio n. When comparing fig. 4b and 4d, it can be seen that Ip' is larger than Ip.
  • Fig. 5a shows phason diagram of MVB without additional reactor or magnetic air gap in the auto transformer.
  • the figure illustrates a typical diagram of the system in fig. 1
  • fig. 5b showing a phason diagram of MVB with additional reactor or magnetic air gap in auto transformer, illustrates the same operation situation when using the system according to fig. 2 or 3.
  • the length of the vector U MCI is reduced in fig. 5b, which indicates that there are lower voltages over the controllable inductor B.
  • Fig. 6 is an electromechanical sketch of an autotransformer without a magnetic air gap in MVB, and fig. 7 shows the same, but with a magnetic air gap in MVB.
  • Fig. 6 is a prior art transformer comprising a toroid magnetic core 10 and a primary winding 12 and a secondary winding 14 wound around the core 10.
  • the autotransformer in the preferred embodiment of the system according to the invention can be made by dividing the core 10 into two halves and then insert a non-magnetizable material between the two halves, as shown in fig. 7 with the magnetic air gap.
  • the system according to the invention comprises a magnetizing inductance, which provides an increase in the magnetizing current of the autotransformer. Consequently, the total harmonic distortion THD is reduced. Moreover, it can be seen that the angle ⁇ between the output voltage Uout and the input voltage Uin is reduced, consequently the power factor PF is improved.
  • the magnetizing inductance can be provided by a magnetic air gap in the core of the autotransformer or can be provided by separate inductor connected in parallel to the parallel winding 4 of the autotransformer.
  • the system further comprises a control circuit, which based on measured voltages and/or currents, controls the control current of the control winding 3, thereby controlling the inductance of the magnetic controllable inductor B.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Ac-Ac Conversion (AREA)

Abstract

Cette invention concerne un système de stabilisation de tension et de réduction de la distorsion harmonique totale dans des lignes de transport d’énergie, pour chaque phase, comprenant : un autotransformateur (A) avec un bobinage série (7) et un bobinage parallèle (4), le bobinage série (7) étant raccordé entre une tension d’entrée Uin et une tension de sortie Uout ; un inducteur à commande magnétique (B) comprenant un bobinage primaire (2) enroulé autour d’un noyau et un bobinage de commande (3) enroulé autour du noyau, le bobinage de commande (3) étant conçu pour créer un champ magnétique essentiellement orthogonal au champ créé par le bobinage primaire (2), ce qui commande l’inductance de l’inducteur à commande magnétique (B) ; le bobinage parallèle (4) de l’autotransformateur étant raccordé entre la tension d’entrée Uin et le bobinage primaire (2) de l’inducteur à commande magnétique (B), l’autre borne du bobinage primaire (2) étant raccordée au point neutre. Le système comprend également une inductance d’aimantation, qui accroît le courant magnétisant de l’autotransformateur. L’inductance d’aimantation peut être fournie par un entrefer magnétique dans le noyau de l’autotransformateur. Sinon, l’inductance d’aimantation peut être fournie par un autre inducteur raccordé en parallèle au bobinage parallèle (4) de l’autotransformateur.
PCT/NO2006/000327 2005-09-23 2006-09-22 Dispositif autotransformateur à entrefer magnétique WO2007035110A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO20054427 2005-09-23
NO20054427A NO324270B1 (no) 2005-09-23 2005-09-23 Autotransformatoranordning med magnetisk luftgap anvendt med magnetisk styrbar induktor

Publications (2)

Publication Number Publication Date
WO2007035110A1 true WO2007035110A1 (fr) 2007-03-29
WO2007035110A9 WO2007035110A9 (fr) 2007-05-18

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NO (1) NO324270B1 (fr)
WO (1) WO2007035110A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009123469A1 (fr) * 2008-03-31 2009-10-08 Magtech As Topologie de dévoltage-survoltage
CN106411115A (zh) * 2016-11-21 2017-02-15 盐城工学院 一种可变电感工作范围连续扩展的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161772A (en) * 1975-11-25 1979-07-17 Moerman Nathan A Conversion and control of electrical energy by electromagnetic induction
EP0684679A1 (fr) * 1994-05-26 1995-11-29 Abb Stromberg Kojeet Oy Méthode pour la réduction de la distorsion de la forme de l'onde en un dispositif électrique et circuit pour un dispositif électrique
WO2004053615A1 (fr) * 2002-12-12 2004-06-24 Magtech As Systeme pour la stabilisation de tension de lignes d'alimentation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161772A (en) * 1975-11-25 1979-07-17 Moerman Nathan A Conversion and control of electrical energy by electromagnetic induction
EP0684679A1 (fr) * 1994-05-26 1995-11-29 Abb Stromberg Kojeet Oy Méthode pour la réduction de la distorsion de la forme de l'onde en un dispositif électrique et circuit pour un dispositif électrique
WO2004053615A1 (fr) * 2002-12-12 2004-06-24 Magtech As Systeme pour la stabilisation de tension de lignes d'alimentation

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009123469A1 (fr) * 2008-03-31 2009-10-08 Magtech As Topologie de dévoltage-survoltage
CN106411115A (zh) * 2016-11-21 2017-02-15 盐城工学院 一种可变电感工作范围连续扩展的方法
CN106411115B (zh) * 2016-11-21 2019-03-08 盐城工学院 一种可变电感工作范围连续扩展的方法

Also Published As

Publication number Publication date
NO20054427L (no) 2007-03-26
WO2007035110A9 (fr) 2007-05-18
NO20054427D0 (no) 2005-09-23
NO324270B1 (no) 2007-09-17

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