EP0132266A1 - Systeme de protection d'un cable a courant continu - Google Patents

Systeme de protection d'un cable a courant continu

Info

Publication number
EP0132266A1
EP0132266A1 EP84900520A EP84900520A EP0132266A1 EP 0132266 A1 EP0132266 A1 EP 0132266A1 EP 84900520 A EP84900520 A EP 84900520A EP 84900520 A EP84900520 A EP 84900520A EP 0132266 A1 EP0132266 A1 EP 0132266A1
Authority
EP
European Patent Office
Prior art keywords
cable
voltage
conducting means
reverse
unidirectional current
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Withdrawn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
EP84900520A
Other languages
German (de)
English (en)
Inventor
Nehemiah Lekaile Diseko
Michael James Boden
Brian Anthony Rowe
Bjarne Reinholdt Andersen
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.)
Associated Electrical Industries Ltd
Original Assignee
Associated Electrical Industries Ltd
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 Associated Electrical Industries Ltd filed Critical Associated Electrical Industries Ltd
Publication of EP0132266A1 publication Critical patent/EP0132266A1/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Withdrawn legal-status Critical Current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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Definitions

  • This invention relates to a high voltage direct current (h.v.d.c.) cable protection system in which the cable polarity .is not required to change suddenly in normal conditions. This may be because the direction of power flow is constantly in one direction or because measures are taken to maintain or reverse gradually the cable polarity in normal conditions in a bidirectional power system.
  • the former case arises where, for example, the h.v.d.c. cable has a dedicated function of supplying a load centre from a generating plant. In such circumstances the cable polarity need never reverse in normal conditions.
  • a high voltage direct current power transmission ' system comprises a high voltage cable having at least one conductor connected between converters at respective terminal stations, characterised in that unidirectional current-conducting means are connected to a said conductor at each terminal station in a direction such as to be reverse-biassed by the normal cable voltage polarity, each current-conducting means incorporating a resistive component and the arrange- ment being such that in a fault condition, reverse voltage , on the cable is limited by the voltage drop across the unidirectional current-conducting means.
  • the unidirectional current-conducting means may comprise a diode rectifier or a gated thyristor, which may be connected in series with a resistor.
  • Said cable may be a polar cable, in which case the unidirectional current-conducting means is suitably connected between the cable core and earth and is arranged to limit any reverse fault voltage to below the rated reverse voltage of the cable.
  • a polar cable is meant any cable which can withstand a significantly higher voltage of normal polarity than of reverse polarity.
  • the invention is also applicable to a bidirectional power transmission system employing a non- polar cable.
  • the polarity of the unidirectional current-conducting means may be reversed so as to maintain its reverse bias irrespective of the relative polarity of the cable conductors, so as to allow the direction of power transmission to be reversed (accompanied by a slow and therefore harmless voltage reversal) but to quench any sudden voltage reversal caused by a fault condition.
  • each unidirectional current-conducting means is preferably equal to that of each of the others.
  • Figure 1 is a diagram of an h.v.d.c. scheme includin terminal stations
  • Figure 2 is a diagram of one of the terminal stations
  • Figure 3 is a current/time diagram showing fault currents with different resistive components
  • Figure 4 is a diagram of a monopolar terminal statio adapted to accommodate the invention in a bidirectional powe system;
  • Figure 5 is a ' similar diagram in respect of a bipola terminal station
  • Figure 6 is a diagram showing two similar bipolar terminal stations employing a non-polar cable.
  • generating plant at station A is required to supply power to a load centre connected to station B.
  • the plant at station A includes a rectifier r supplied from a 3-phase a.c. system.
  • the rectifier feeds the d.c. cable C through a large reactor Lr the cable core being positive with respect to the cable sheath, which is earthed.
  • the cable is again connected by way of a large reactor L. , to an inverter i.
  • the lead centre is then connected to the a.c. output of the inverter.
  • At each station there is a surge arrester S connected between the cable and earth to limit the over- voltage (irrespective of polarity) that the equipment may have to sustain.
  • the system is conventional.
  • the reflected voltage V in terms of the incident voltage V. is given as follows:
  • the effective d.c. reactor impedance Z. is normally much greater than the cable surge impedance Z so that the reflected voltag-e surge is comparable with the incident voltage surge in magnitude, and is of the same polarity. From the initial positive voltage prior to the fault the cable termination would be subjected to an almost instantaneous polarity reversal. Significant damage could then ensue unless the cable has been specifically designed and constructed (at increased cost) to withstand this duty.
  • a diode D is connected between the core and earth in such a direction as to be non-conductive in normal circumstances, i.e. with the cable core positive with respect to earth. The diode is connected where the reverse voltage would first occur, i.e. at the junction of the cable and the reactor Lr.
  • a diode connected in this way would achieve the object of limiting the reverse voltage applied to the cable but would leave a very large current flowing through the cable, the fault and the diode.
  • This fault current is given by the initial voltage and the surge impedance and could typically be 1000 kV720 ohms, i.e. 50 kA. Since there are normally very few losses in such an arrangement a substantial part of the initial energy stored in the cable would be dissipated in the diode. Using a standard diode therefore, it is preferable to remove the energy dissipation to a relatively robust and cheap resistor R connected in series with the diode.
  • This resistor may have a resistance in the range 0.5 to 5 ohms (preferably about 1.5 ohms), be capable of carrying 50 - 100 kA, and dissipating energy of typically 25 MJ.
  • the use of a resistor in this way does mean, of course, that the cable will be subjected to a limited voltage polarity reversal to " the extent of perhaps 10% of the pre-fault voltage. This will generally be tolerable.
  • a non-linear resistor of zinc-oxide for example, can be used instead of a linear resistor R .
  • the resistance of such a resistor increases with decreasing current and tends • to suppress the fault current much more quickly.
  • Figure 3 illustrates the effect in the circuit of Figure 2 of three different resistances, namely zero (for the diode alone), 1.5 ohms for the linear resistor, and, in broken line, the non-linear zinc-oxide resistor.
  • a thyristor may be used instead of a diode.
  • the thyristor may be continuously gated by a constant d.c. or may be supplied with gating current in response to a detected voltage reversal arising from a fault condition.
  • each cable may have its own diode/resistor termination, so that in the event of a fault, the terminations carry currents determined by their resistor values.
  • the current sharing and hence the distribution of the energy to be absorbed in such conditions can therefore be controlled by proper matching of the total resistance in each termination.
  • a single diode or diode/resistor termination may be used for a number of parallel cables although this has the disadvantage of disabling all of the parallel cables if the termination fails.
  • Figure 4 illustrates how the Invention can still be incorporated in such a system.
  • a reversing switch is connected in the output of the rectifier r (and similarly in the Input to the inverter at station B not shown) and is operated in synchronism with the direction of power flow.
  • the switch is operated and the cable polarity remains constant.
  • Figure 5 shows a comparable arrangement for a bipolar converter system in which the converter at station A comprises two rectifier groups connected in series and the centre connection earthed. The cable conductors are then normally balanced about earth potential, being connected to the positive and negative rectifier outputs respectively.
  • FIG. 6a shows a terminal station connected to a bipolar cable C.
  • the polarity of the core of the cable is dependent on the direction of power transmission (which in turn depends on the firing angle of converter r).
  • diode D is mounted on a two-position mechanicall rotatable arm which engates fixed terminals U1 and U2.
  • the arm is controlled by an electromagnetic actuator indicated schematically as A, in dependence upon a polarity signal from converter R, so as to maintain diode D in a nominally reverse biassed condition. Any sudden voltage reversal caused by a fault condition will be quenched by diode D and resistor R.
  • Figure 6b shows a similar arrangement in which two reverse parallel-connected thyristors controlled by a gating circuit L replace the mechanical arrangement of Figure 6a.
  • thyristor T1 When the core of cable C is negative thyristor T1 is switched on and thyristor T2 is switched off in accordance with a polarity signal from converter R to gating circuit L.
  • T1 When the core of cable C is positive, T1 is switched on and T2 is switched off.
  • the invention is applicable to transmission systems employing two conductors in a common cable, the conductors carrying the forward and return currents respectively.
  • the uni ⁇ directional current-conducting means is suitably connected directly between the two conductors.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

Système de protection d'un câble à haute tension et à courant continu, dans lequel un câble de transmission possède une polarité normale par rapport à la terre déterminée par un sens d'écoulement normal du courant. Dans l'éventualité d'une défaillance, une onde de surtension réfléchie sur la ligne peut dans certains cas donner une tension de polarité inversée à 100 % sur la ligne, ce qui provoque des dégâts du câble sauf s'il a été conçu pour supporter une telle inversion de tension (à des frais supplémentaires considérables). Selon l'invention, un redresseur à diode est connecté entre les lignes à chaque extrémité du câble dans un sens tel qu'il est polarisé de manière inverse en fonctionnement normal. Une tension inverse sur la ligne est donc limitée à la chute dans le sens direct de la diode. Comme cela provoquerait un courant de défaut de la diode très important, une résistance est montée en série avec la diode pour limiter le courant même si c'est au sacrifice d'une petite tension inverse.
EP84900520A 1983-01-14 1984-01-13 Systeme de protection d'un cable a courant continu Withdrawn EP0132266A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8300991 1983-01-14
GB838300991A GB8300991D0 (en) 1983-01-14 1983-01-14 Cable protection system

Publications (1)

Publication Number Publication Date
EP0132266A1 true EP0132266A1 (fr) 1985-01-30

Family

ID=10536337

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84900520A Withdrawn EP0132266A1 (fr) 1983-01-14 1984-01-13 Systeme de protection d'un cable a courant continu

Country Status (4)

Country Link
EP (1) EP0132266A1 (fr)
GB (2) GB8300991D0 (fr)
IT (1) IT1196677B (fr)
WO (1) WO1984002807A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO312080B1 (no) * 2000-04-28 2002-03-11 Aker Eng As Distribusjonssystem for elektrisk kraft
EP2569843B1 (fr) * 2010-05-11 2014-01-15 ABB Technology AG Installation pour transmettre de l'énergie électrique cc à haute tension et comprenant une protection contre les surtensions
WO2012055447A1 (fr) 2010-10-29 2012-05-03 Abb Technology Ag Équilibrage de tension de lignes de transmission à ccht en monopole symétrique après les défauts de terre
WO2015024950A1 (fr) * 2013-08-21 2015-02-26 Alstom Technology Ltd Protection électrique côté ca d'un hvdc
DE102022206731A1 (de) * 2022-06-30 2024-01-04 Gts Deutschland Gmbh Schutzvorrichtung zum schutz einer elektrischen gleisfeld-infrastruktur, gleisfeld-energieversorgungseinrichtung und verfahren zur begrenzung von potentialverschiebungen in einer elektrischen gleisfeld-infrastruktur

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8402807A1 *

Also Published As

Publication number Publication date
GB8300991D0 (en) 1983-02-16
IT1196677B (it) 1988-11-25
WO1984002807A1 (fr) 1984-07-19
GB8400612D0 (en) 1984-02-15
IT8467041A0 (it) 1984-01-16
GB2133939A (en) 1984-08-01

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Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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17P Request for examination filed

Effective date: 19840913

AK Designated contracting states

Designated state(s): AT BE CH DE FR GB LI LU NL SE

RBV Designated contracting states (corrected)

Designated state(s): AT BE CH DE FR LI LU NL SE

17Q First examination report despatched

Effective date: 19860205

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19860617

RIN1 Information on inventor provided before grant (corrected)

Inventor name: BODEN, MICHAEL, JAMES

Inventor name: ANDERSEN, BJARNE, REINHOLDT

Inventor name: DISEKO, NEHEMIAH, LEKAILE

Inventor name: ROWE, BRIAN, ANTHONY