EP2332228A1 - Agencement d'interconnexion de deux emplacements distants et procede de transmission d'energie electrique - Google Patents

Agencement d'interconnexion de deux emplacements distants et procede de transmission d'energie electrique

Info

Publication number
EP2332228A1
EP2332228A1 EP08803723A EP08803723A EP2332228A1 EP 2332228 A1 EP2332228 A1 EP 2332228A1 EP 08803723 A EP08803723 A EP 08803723A EP 08803723 A EP08803723 A EP 08803723A EP 2332228 A1 EP2332228 A1 EP 2332228A1
Authority
EP
European Patent Office
Prior art keywords
phase
transmission line
cables
voltage
cable
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP08803723A
Other languages
German (de)
English (en)
Inventor
Stefan Thorburn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NKT HV Cables GmbH
Original Assignee
ABB Research Ltd Switzerland
ABB Research Ltd Sweden
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 ABB Research Ltd Switzerland, ABB Research Ltd Sweden filed Critical ABB Research Ltd Switzerland
Publication of EP2332228A1 publication Critical patent/EP2332228A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • 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
    • H02J3/1878—Arrangements for adjusting, eliminating or compensating reactive power in networks using tap changing or phase shifting transformers
    • 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 present invention relates to an arrangement for intercon- necting two distant locations of a meshed grid for power transmission through high voltage alternating current, said grid carrying a three-phase alternating voltage on said locations, said arrangement comprising on each said location voltage transforming means connecting to the respective grid location and configured to generate a 2n-phase voltage as well as a 2n- phase cable transmission line interconnecting said voltage transforming means and having cables extending in n couples with cables of the same couple close to each other with a phase shift of substantially ⁇ radians of the currents in the respective two cables of each said couple, n being an integer > 1 , as well as a method for transmitting electric power between two distant locations of a meshed grid according to the preamble of the appended independent method claim.
  • a meshed grid for power transmission is defined as a power transmission network in which power may be transmitted through alternative paths running electrically in parallel with each other between different locations of said grid.
  • Electric power may still be transmitted between two said locations through another path.
  • disant does here mean a distance between said locations of at least 5 km and may well be in the order of several hundreds of km or even greater.
  • Said cables of said cable transmission line may be of any type having an inner metallic conductor surrounded by a thick insulating layer, for instance of oil impregnated paper or on polymer base, such as in a PEX-cable, and with an outer semi-conduct- ing shield.
  • This object is according to the invention obtained by providing such an arrangement, which further comprises on-load tap changers connecting to the 2n-phase side of each said voltage transforming means and means configured to control said tap changers for controlling the voltage on said transmission line and by that production of reactive power in said cables.
  • the voltage on the cable transmission line may be varied by controlling said tap changers, so that the voltage may be lowered considerably during low load operation, i.e. when a comparatively small amount of electric power is to be transmitted through said grid between two said two locations, which results in a considerable reduction of reactive power generation, since this is substantially proportional to the square of the volt- age, i.e. U 2 .
  • the tap changers and by that said voltage the relationship of the power transmitted between said two locations over said cable transmission line and another transmission line in parallel therewith may be controlled with an aim to minimise the total power transmission losses of said grid.
  • said on-load tap changers connecting to phases associated with the same said couple of cables are individually controllable. This possibility to individual control makes it possible to obtain a balance of the currents flowing in the cables of each couple, but it is also possible to deliberately create some unbalance and by that increase the reactance of the cable transmission line for increasing the amount of electric power transmitted through other paths between said two locations and by that obtain an optimum said relationship.
  • the arrangement comprises a phase shifting transformer connecting to at least one said cable of each couple of cables on said 2n-phase side of each said voltage transforming means and means for controlling said phase shifting transformers for controlling the active power transmitted through said transmission line.
  • active power may be steered away from the cable transmission line by altering the phase angle of the voltage in the respective phase.
  • control the phase shifting transformers for changing the relationship of electric power transmitted through the respective phases, i.e. move power from one phase to another.
  • the phase shifting transformer and the on-load tap changer for the same phase may also be combined in a single unit as shown in for instance WO 2006/022576 A1 .
  • the arrangement comprises a separate phase shifting transformer for each phase on the 2n-phase side of the respective said voltage transforming means. This results in a high flexibility of the control of active power transmitted through the cable transmission line.
  • the arrange- ment further comprises an inductive means and a power semiconductor switch associated therewith connecting to at least one said cable of each couple of cables on said 2n-phase side of each said voltage transforming means and means configured to control the respective said switch for optionally switching in said inductive means in series between said voltage transforming means and said cable for adjusting the impedance of said trans- mission line.
  • the inductance and by that the reactance of the cable transmission line may in this way be altered by changing periods of time of switching in inductive means, so that the relationship of active power transmitted through the cable transmis- sion line and through other paths between said two locations may be adjusted so as to obtain a minimum of total losses for the power transmission on the grid.
  • the power semiconductor switch may include power semiconductor devices of any known type, such as thyristors and IGBT:s.
  • the arrangement comprises a separate said inductive means and power semiconductor switch with associated control means for each of the 2n-phases of said cable transmission line. This increases the controllability of active power transmission over the cable transmission line.
  • control means for the power semiconductor switches associated with the inductive means are configured to control the switching in of said inductive means so as to obtain a balance of the currents flowing in the respective two cables of each said couple, i.e. substantially the same magnitude of these currents.
  • the arrangement further comprises a capacitive means and a power semiconductor switch associated therewith connecting to at least one said cable of each couple of cables on said 2n-phase side of each said voltage transforming means and means configured to control the respective said switch for optionally switching in said capacitive means in series between said voltage transforming means and said cable for adjusting the impedance of said transmission line.
  • the switching in of such a series capacitance may be used for increasing the share of active power transmit- ted through said cable transmission line with respect to any parallel path.
  • the power electronics mentioned above so that they become a Switching Converter Type Series Compensation such as an SSSC. This solution can then resemble the impact of the controllable inductance or the controllable capacitance on the system as discussed in the previous sections.
  • the arrangement further comprises a Switching Converter Type Series Compensation means connecting to at least one said cable of each couple of cables on said 2n-phase side of each said voltage transforming means for adjusting the impedance of said transmission line by controlling power semiconductor devices of turn-off type, such as IGBT:s or GTO:s.
  • power semiconductor devices of turn-off type such as IGBT:s or GTO:s.
  • said 2n-phase cable transmission line is connected in parallel with at least one uninsulated overhead transmission line extending between said grid locations.
  • each said voltage transforming means comprises in the 6-phase embodiment two 3-phase transformers connected in parallel with each other to the respective grid location, and these transformers are configured to each provide one of the two phases for each couple of cables.
  • the on-load tap changers connecting to phases of the six-phase side associated with the same transformer are configured to be controlled jointly and independently of the control of the on-load tap changers associated with the phases of the other transformer.
  • the on-load tap changers belonging to the same transformer controlled jointly, and it is at the same time preferred to provide for an independent control of the on-load tap changers of the different transformers making it possible to control the inductance and by that the reactance of the cable transmission line.
  • said appara- tus is configured to send the result of said calculation also to said means for controlling said phase shifting transformers, and the means last mentioned is configured to carry out said control of said phase shifting transformers on the basis of the result of said calculation so as to obtain said optimum share for trans- mission on said 2n-phase cable transmission line.
  • said apparatus is configured to send the result of said calculation also to said means for controlling said power semiconductor switches for switching in said inductive means, and the means last mentioned is configured to carry out said control of said switches on the basis of the result of said calculation so as to obtain said optimum share for said 2n-phase cable transmission line.
  • the three embodiments last mentioned makes it possible to reduce the total power losses in power transmission over said meshed grid between said two locations thereof.
  • the arrangement and controllability of the tap changers, phase shifting transformers and the series reactance (inductive means) have different advantages, especially in different operation conditions, as appearing from above and from the following description.
  • the arrangement is configured to transmit powers above 1 MW between said locations and or carrying voltages above 1 kV, especially 10 kV - 500 kV, on said transmission line.
  • the invention also relates to a method for transmitting electric power between two distant locations of a meshed grid for power transmission through a high voltage alternating current accord- ing to the appended independent method claim.
  • Fig 1 is a very schematic view illustrating a meshed grid for power transmission through high voltage alternating current (HVAC) with an arrangement according to a first embodiment of the invention connected between two distant locations of said grid,
  • HVAC high voltage alternating current
  • Fig 3-5 are views corresponding to fig 2 of an arrangement according to a third, fourth and fifth, respectively, embodiment of the invention.
  • the arrangement according to the invention comprises on each said location two 3-phase transformers 6, 7 connected in parallel with each other to the grid location.
  • the transformers are configured to be controlled to generate a 6-phase voltage and connected to a 6-phase cable transmission line 8 having cables 9-14 extending in three couples 15-17 close to each other.
  • the phases of said transformers are connected to the cables so that a phase shift of substantially ⁇ radians of the currents in the respective two cables of each said couple is achieved as illustrated by the arrows.
  • the arrangement of said cables in such couples will result in a very low inductance and by that reactance of the transmission line.
  • the overhead line 4 will have a much higher impedance, so that most of the active power tends to flow through the cable transmission line 8 between said two locations 2, 3.
  • the arrangement also comprises one on-load tap changer 18-23 connected to each phase of the transformers on the 6-phase side of the transformers and means 24, 25 configured to control the tap changers for controlling the voltage on the cable transmission line.
  • Said means 24, 25 are configured to control the tap changers associated with the same transformer jointly and the tap changers associated with different transformers independ- ently.
  • the arrangement also comprises an apparatus 26 configured to receive information about the total electric power to be transmitted for the present through the meshed grid 1 between the two locations 2, 3 and on the basis of this information to calcu- late an optimum share of this total electric power to be transmitted through the 6-phase cable transmission line while considering power losses and/or balance of load on parts of the meshed grid interconnecting the two locations.
  • This apparatus 26 is configured to send the result of said calculation to the means 24, 25, which are configured to carry out the control of the tap changers on the basis of the result of this calculation so as to obtain said optimum share of power for transmission on the 6-phase cable transmission line.
  • Fig 2 illustrates very schematically an arrangement according to a second embodiment of the invention, in which of the 6-phase thereof only two phases with associated equipment are shown for making the drawing clearer, but the other four phases are correspondingly designed. Parts of this embodiment corresponding to parts of the embodiment shown in fig 1 have been provided with the same reference numerals.
  • the on-load tap changer 18', 21 ' are here combined with a phase shifting trans- former 27, 28, and the respective such unit 29, 30 is here controlled by the means 24', 25'.
  • the active power P transmitted over a transmission line between two locations at voltages U 1 and U 2 may be expressed as
  • phase shifting transformer ⁇ By controlling the phase shifting transformer ⁇ may be changed and by that the power transmitted through the cable transmission line may be regulated, thus increasing the controllability of the load flow in the meshed grid.
  • the phase shifting transformers may also be controlled to change the proportion of active power transmitted through the different phases.
  • the relationship between the active power transmitted through the cable transmission line and through a parallel line, such as an over- head line, may be efficiently controlled by controlling the phase shifting transformers.
  • Fig 3 illustrates an arrangement according to a third embodiment of the invention differing from that shown in fig 2 by the fact that a power electronic unit 30 including an inductive means 31 and a power semiconductor switch 32 associated therewith is connected to each cable of the cable transmission line, in which the power semiconductor switch here is formed by two tyristors 33 connected in anti-parallel and controllable through the con- trol means 24", 25" for optionally switching in the inductive means 31 in series with the respective cable for adjusting the reactance X thereof and by that the active power P transmitted therethrough according to the formula (1 ).
  • the tap changing means may be used for changing the voltage and by that the generation of reactive power and for changing the flow of active power in the cable transmission line, the phase shifting transformer for regulating the flow of electric power in the transmission line and the controllable series reactance to also control the flow of active power through the cable transmission line.
  • the control of the switches for the inductive means 31 is very fast and suitable for maintaining a perfect balance between currents flowing in the cables of the same couple of cables when desired for reducing the reactance during normal load operating.
  • the phase shifting transformer and the controllable series reactance are supplements to each other. When hardly no current is flowing in the cable transmission line the control of the series reactance may nearly not influence the transmission of active power, but the phase shifting transformer may have a considerable influence and the control thereof may result in an increased current, whereupon a control of the series reactance may have a noticeable influence upon said active power transmission. When the current is high, the control of the series reactance will be more efficient and faster than that of the phase shifting transformer.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

L'invention porte sur un agencement d'interconnexion de deux emplacements distants (2, 3) d'un réseau maillé de transmission d'énergie par courant alternatif haute tension, lequel agencement comprend, sur chaque emplacement, des moyens de transformation de tension (6, 7) configurés pour générer une tension à 2n-phases ainsi qu'une ligne de transmission par câble à 2n-phases(8) interconnectant les moyens de transformation de tension et comprenant des câbles s'étendant en n couples. Les câbles du même couple sont proches l'un de l'autre, un déphasage de sensiblement π radians des courants existant dans les deux câbles respectifs de chacun desdits couples et n étant un entier > 1. L'agencement comprend en outre des commutateurs à prises de réglage (18-23) connectés au côté à 2n-phases de chaque moyen de transformation de tension.
EP08803723A 2008-09-05 2008-09-05 Agencement d'interconnexion de deux emplacements distants et procede de transmission d'energie electrique Withdrawn EP2332228A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2008/061754 WO2010025771A1 (fr) 2008-09-05 2008-09-05 Agencement d'interconnexion de deux emplacements distants et procédé de transmission d'énergie électrique

Publications (1)

Publication Number Publication Date
EP2332228A1 true EP2332228A1 (fr) 2011-06-15

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP08803723A Withdrawn EP2332228A1 (fr) 2008-09-05 2008-09-05 Agencement d'interconnexion de deux emplacements distants et procede de transmission d'energie electrique

Country Status (2)

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EP (1) EP2332228A1 (fr)
WO (1) WO2010025771A1 (fr)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040100230A1 (en) * 2002-11-25 2004-05-27 Per Halvarsson Device and a method for control of power flow in a transmission line

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB189931A (en) 1921-10-12 1922-12-14 Alfred Mills Taylor Means for improving the current carrying capacity of existing three-phase alternating current cable systems
DE581791C (de) * 1931-05-05 1933-08-03 Aeg Mehrphasenstrom-UEbertragungssystem
SU566288A1 (ru) 1974-03-21 1977-07-25 Отдел Энергетической Кибернетики Ан Молдавской Сср Электропередача переменного тока
EP1794861A1 (fr) 2004-08-27 2007-06-13 Abb Research Ltd. Reglage de debit de puissance electrique

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040100230A1 (en) * 2002-11-25 2004-05-27 Per Halvarsson Device and a method for control of power flow in a transmission line

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
See also references of WO2010025771A1 *
SEITLINGER W: "PHASENSCHEIBER-TRANSFORMATOREN-DISKUSSION SPEZIELLER EIGENSCHAFTEN", ELEKTROTECHNIK UND INFORMATIONSTECHNIK, SPRINGER VERLAG, WIEN, AT, vol. 115, no. 12, 1 January 1998 (1998-01-01), pages 662 - 665, XP000876206, ISSN: 0932-383X *

Also Published As

Publication number Publication date
WO2010025771A1 (fr) 2010-03-11

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