EP0132266A1 - Direct current cable protection system - Google Patents
Direct current cable protection systemInfo
- 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- Withdrawn
Links
- 230000005540 biological transmission Effects 0.000 claims abstract description 15
- 239000004020 conductor Substances 0.000 claims description 15
- 230000002457 bidirectional effect Effects 0.000 claims description 7
- KKEBXNMGHUCPEZ-UHFFFAOYSA-N 4-phenyl-1-(2-sulfanylethyl)imidazolidin-2-one Chemical compound N1C(=O)N(CCS)CC1C1=CC=CC=C1 KKEBXNMGHUCPEZ-UHFFFAOYSA-N 0.000 claims description 2
- 238000010791 quenching Methods 0.000 claims description 2
- 230000007423 decrease Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 6
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 229960001296 zinc oxide Drugs 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000021715 photosynthesis, light harvesting Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
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.
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.A system for protecting a high voltage, direct current cable, in which a transmission cable has a polarity normal to earth determined by a normal direction of current flow. In the event of a fault, a surge wave reflected onto the line can in some cases result in 100% reverse polarity voltage on the line, causing damage to the cable unless it has been designed to withstand such voltage reversal (at considerable additional cost). According to the invention, a diode rectifier is connected between the lines at each end of the cable in such a direction that it is reversely biased in normal operation. A reverse voltage on the line is therefore limited to the drop in the forward direction of the diode. As this would cause a very large diode fault current, a resistor is connected in series with the diode to limit the current even if it is at the sacrifice of a small reverse voltage.
Description
Claims
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 (en) | 1985-01-30 |
Family
ID=10536337
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84900520A Withdrawn EP0132266A1 (en) | 1983-01-14 | 1984-01-13 | Direct current cable protection system |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0132266A1 (en) |
GB (2) | GB8300991D0 (en) |
IT (1) | IT1196677B (en) |
WO (1) | WO1984002807A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NO312080B1 (en) * | 2000-04-28 | 2002-03-11 | Aker Eng As | Electric power distribution system |
WO2011141052A1 (en) * | 2010-05-11 | 2011-11-17 | Abb Technology Ag | A plant for transmitting high voltage dc electric power including overvoltage protection |
US9054557B2 (en) | 2010-10-29 | 2015-06-09 | Abb Technology Ag | Voltage balancing of symmetric HVDC monopole transmission lines after earth faults |
EP3036813B1 (en) | 2013-08-21 | 2022-04-27 | General Electric Technology GmbH | Electric protection on ac side of hvdc |
DE102022206731A1 (en) * | 2022-06-30 | 2024-01-04 | Gts Deutschland Gmbh | PROTECTIVE DEVICE FOR PROTECTING AN ELECTRICAL TRACK FIELD INFRASTRUCTURE, TRACK FIELD ENERGY SUPPLY DEVICE AND METHOD FOR LIMITING POTENTIAL SHIFT IN AN ELECTRICAL TRACK FIELD INFRASTRUCTURE |
-
1983
- 1983-01-14 GB GB838300991A patent/GB8300991D0/en active Pending
-
1984
- 1984-01-11 GB GB08400612A patent/GB2133939A/en not_active Withdrawn
- 1984-01-13 WO PCT/GB1984/000008 patent/WO1984002807A1/en not_active Application Discontinuation
- 1984-01-13 EP EP84900520A patent/EP0132266A1/en not_active Withdrawn
- 1984-01-16 IT IT67041/84A patent/IT1196677B/en active
Non-Patent Citations (1)
Title |
---|
See references of WO8402807A1 * |
Also Published As
Publication number | Publication date |
---|---|
IT8467041A0 (en) | 1984-01-16 |
IT1196677B (en) | 1988-11-25 |
GB2133939A (en) | 1984-08-01 |
GB8400612D0 (en) | 1984-02-15 |
WO1984002807A1 (en) | 1984-07-19 |
GB8300991D0 (en) | 1983-02-16 |
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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 |
Free format text: ORIGINAL CODE: 0009012 |
|
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 |