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WO2012034593A1 - Agencement d'alimentation pour poste électrique - Google Patents

Agencement d'alimentation pour poste électrique Download PDF

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Publication number
WO2012034593A1
WO2012034593A1 PCT/EP2010/063615 EP2010063615W WO2012034593A1 WO 2012034593 A1 WO2012034593 A1 WO 2012034593A1 EP 2010063615 W EP2010063615 W EP 2010063615W WO 2012034593 A1 WO2012034593 A1 WO 2012034593A1
Authority
WO
WIPO (PCT)
Prior art keywords
power
voltage
transformer
power supply
supply arrangement
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.)
Ceased
Application number
PCT/EP2010/063615
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English (en)
Inventor
Lars-Erik Juhlin
Gunnar Asplund
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.)
ABB Technology AG
Original Assignee
ABB Technology AG
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 Technology AG filed Critical ABB Technology AG
Priority to PCT/EP2010/063615 priority Critical patent/WO2012034593A1/fr
Publication of WO2012034593A1 publication Critical patent/WO2012034593A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • H02J11/00—Circuit arrangements for providing service supply to auxiliaries of stations in which electric power is generated, distributed or converted
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/02—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC
    • H02M5/04—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters
    • H02M5/06—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters using impedances
    • H02M5/08—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters using impedances using capacitors only

Definitions

  • the present invention relates to power supply of devices in substations. More particularly the present invention relates to a power supply arrangement for such a substation.
  • Substations are used as interfaces between different parts of power transmission systems and as interfaces between different types of power transmission systems.
  • the transmission system is the high voltage (HV) or extra high voltage (EHV) backbone of a power
  • a substation may be connected to an AC power line and include devices such as converters, for instance for converting between AC and DC or from AC to AC. They may also or instead include
  • a substation is thus involved in the transfer of electrical power.
  • the substation involved in this transmission of electrical power also needs to be supplied with electrical power in order to perform a number of activities, such as protection and control of
  • transformers and converters There are also other devices in a substation needing such power supply, for instance cooling devices such as fluid pumps and valves. Because of the reliability requirements of the power transmission system also the power supply of the substation has to be reliable.
  • the substation As the substation is transferring power, it is then of interest to tap off some of this power from the AC power line in order to operate the various devices of the substation, i.e. in order to supply these devices with power for their operation.
  • This may be needed if there is no local power distribution system at hand or if there is such a local power distribution system at hand that has too low reliability.
  • redundancy is often needed. There is therefore a need for two independent sources of auxiliary power, where the local power distribution system may be one and a tap off arrangement may be another. It is also possible with two separate tap off arrangements .
  • a tapping off of power can be performed using a transformer rated for the full high voltage of the power transmission system, for instance an additional transformer connected to the AC power line. If the substation comprises a transformer employed in the transfer of power it is also possible to tap off such power using an additional auxiliary power winding on this transformer.
  • transformer for the full voltage in the substation may for a number of reasons also be less interesting. One reason is that it may not be needed for other purposes. When the substation is not feeding any network of lower order, no transformer may be needed for the main purpose of the substation of transmitting power at the high voltage level. It may also be of interest to avoid using such a transformer even when there is one present in the substation, for instance in order to keep the energy tapping technique uninfluenced by the
  • the present invention is directed towards solving this problem.
  • One object of the present invention is to provide a power supply arrangement for a substation, which taps off power from an AC power line without the use of a transformer connected to this power line.
  • This object is according to the present invention obtained through a power supply arrangement for a substation, where the power supply arrangement
  • a group of reactive voltage dividing elements connected to a first AC power line, where the first AC power line transports AC power to or from the substation, and
  • the primary winding is connected in parallel with at least one of the voltage dividing elements and the secondary winding is coupled to the substation for providing AC power for powering devices of the
  • Coupled used is intended to cover the possibility of an indirect electrical connection between two elements. There may thus be one or more elements placed between two elements defined as being coupled to each other.
  • connected is on the other hand intended to mean a direct galvanic connection of two entities to each other without any entity between them.
  • the present invention has a number of advantages. It allows the use of smaller transformers in the tapping off of power from an AC power line. In this way an economical power supply arrangement can be obtained. This is done through using reactive voltage dividing elements, which are often present for other reasons.
  • fig. 1 schematically shows a single line diagram of a first power line connected to a substation together with a power supply arrangement according to the invention connected between the first power line and the substation, and
  • fig. 2 schematically shows a single line diagram of one embodiment of the power supply arrangement together with the first power line and a load.
  • the invention concerns the tapping off of power from a power line in a power transmission system to a
  • HVDC Voltage Direct Current stations. They may as an example be used in order to generate reactive power.
  • the present invention is particularly suited for being employed in relation to an HVDC substation. It should however be realized that the invention is not limited to HVDC substations.
  • a first AC power line 10 being connected to the AC side of a converter 16 for
  • This converter 16 also has a DC side to which a DC power line 14 is connected.
  • the converter 16 is here a part of a substation 12, which substation 12 is indicated through a dashed box.
  • a power supply arrangement 18 according to the invention, which power supply arrangement 18 is connected to the first AC power line 10 as well as to the substation 12.
  • the first AC power line 10 transports AC power to or from the substation 12.
  • the functioning of the arrangement 18 is to tap some of this AC power from the first power line 10 and use this tapped-off power for operating devices of the substation 12.
  • the substation 12 is furthermore used for conversion between a high AC voltage and a high DC voltage.
  • the first AC power line 10 may therefore be a power line in a high voltage AC power transmission system, while the DC power line may be a part of a high voltage direct current power transmission system (HVDC) .
  • HVDC high voltage direct current power transmission system
  • the first AC power line 10 is directly connected to the converter 16. This means that in the exemplifying environment shown in fig. 1, no high voltage transformer is needed for the converter. It lacks a transformer between converter 16 and first AC power line 10. However, it should be realized that this is no requirement, but the power supply
  • Fig. 2 shows a single line diagram of a power supply arrangement 18 according to a first embodiment of the invention being connected between the first power line 10 and a load 36, where the load 36 may be one or more of the devices in the substation of fig. 1. In fig.
  • first group 21 of reactive voltage dividing elements connected to the first power line 10. They are also connected to ground and therefore connected between the first power line 10 and ground.
  • the group 21 here includes a first, second and third reactive voltage dividing element 20, 22 and 24 connected in series between the first power line 10 and ground. It should here be realized that the number of elements shown are only three in order to better describe the invention. The group 21 may and normally does include many more elements. In this first
  • the reactive voltage dividing elements are all capacitors. In alternative variations of the invention, they may be reactors.
  • the power supply arrangement 18 also comprises a first transformer 26 that is rated for a lower voltage than the transmission system voltage used on the first AC power line.
  • the first transformer 26, has a primary winding PW connected in parallel with at least one of these voltage dividing elements, which may be in parallel with one of them. In this first embodiment it is connected to only one such element, which element is the third element 24 closest to ground. This is the most practical element to use because the potential of the series connection will be lowest here.
  • the first transformer 26 has a secondary winding SW.
  • the secondary winding SW has a first end coupled to ground and a second end connected to a second power line 30, which second power line 30 in turn leads to a second transformer 34 and more particularly to a primary side of the second transformer 34.
  • the second transformer 34 also has a secondary side, which in turn is connected to the load 36.
  • the primary side of the second transformer 34 is coupled to the secondary winding SW of the first transformer 26 and the secondary side of the second transformer 34 coupled to the substation for supplying power to the devices of this substation.
  • a group of reactive power compensation elements 32 here in the form of a series connection of reactive power compensation elements 32 connected to the second power line 30.
  • the series connection has a first end connected to the second power line 30 as well as a second end, which second end will be described in more detail later.
  • This series connection of reactive power compensation elements could be provided through capacitors connected in series and selectably connected into the series connection in order to provide a variable reactive compensation circuit.
  • the first and second power lines 10 and 30 shown in fig. 2 are furthermore three-phase power lines, which means that they will according to the first embodiment of the invention have three phase voltage conductors, i.e. three conductors intended for carrying phase voltages. This also means that in this first embodiment there will be one group of voltage dividing elements between one phase voltage conductor of the first power line 10 and ground as well as one series connection of reactive compensation elements connected to each phase voltage conductor of the second power line 30.
  • first transformer 26 is in fact a three phase transformer having three primary windings and three secondary windings.
  • second transformer 34 is a three-phase transformer having three primary windings on the primary side and three secondary windings on the secondary side.
  • the primary windings of both the first and second transformers are delta connected, which is indicated with a D in the second transformer, while the secondary windings are Y- connected, indicated with a Y in the second
  • the first transformer 26 is shown as only having a single primary winding PW and a single secondary winding SW even though it is a three-phase transformer. This is done in order to clarify the relationship between the primary windings and the voltage dividing elements to which they are connected.
  • the secondary windings of the first and second transformers are Y-connected, they both have a neutral point. These neutral points are here furthermore coupled to ground, where the neutral point of the secondary windings of the second transformer is directly connected to ground, while the neutral point of the secondary windings of the first transformer is connected to ground via a resistor 28. This is shown in fig. 2 through marking the junction between the first end of the secondary winding SW of the first
  • transformer may be connected.
  • the second ends of the three groups of reactive power compensation elements are connected to each other. This is in fig. 2 also indicated through the second end of the shown group of reactive compensation elements being connected to a junction. Two conductors are here shown as connected to this junction. These two conductors are intended to indicate that the second ends of the two other groups of reactive elements associated with the other phase voltage conductors are connected to this point, which in turn is grounded. In this way the reactive compensation elements are Y- connected with isolated neutral point.
  • the first power line 10 has a first voltage Ul, which is divided down to a second voltage U2 by the third voltage dividing element 24. This is in turn transformed into a third voltage U3 by the first transformer 26. Finally the third voltage U3 is transformed to a fourth voltage U4 by the second transformer 34.
  • the power supply arrangement may here be a main or a redundant power supply
  • this tapping off of power can be done using a transformer connected to the first AC power line 10, i.e. a transformer rated to the voltage of this first AC power line 10.
  • the first AC power line 10 is provided in a high voltage AC system where the first voltage Ul may as an example be 400 kV. Typically this voltage may be in an interval of 300 - 800 kV. At these voltage levels such a transformer is big and also expensive.
  • the substation 12 lacks such a main transformer. Thus, there is no transformer involved in the transmission of power from the first AC power line 10 to the DC power line 14. There is thus no transformer placed between the first AC power line 10 and the converter 16.
  • the costs involved with providing a separate transformer for supply of power to the devices of the substation are high and therefore an alternative solution is desired.
  • this is solved through providing the group 21 of reactive voltage dividing elements 20, 22, 24, which divide the first voltage by a factor f in order to obtain a second voltage U2 and connecting the first transformer to this second voltage U2 in order to supply the required power.
  • the second voltage U2 may here be a voltage that is set according to the power supply requirements of the substation 12. It has to be high enough to be able to supply the energy required.
  • the relationship between the voltage dividing elements of the group connected in parallel with the primary winding of the first transformer and the whole group 21 is set according to the rated energy requirements of the devices in the substation that are to be powered.
  • the relationship between the third voltage dividing element 24 and the whole group 21 is set according to the reactive power rating, Mvar rating, of the group 21 and here the rating of the total capacitance of the series-connected group, the size of the voltage Ul and the required active power.
  • the factor f may here be in the range of 1.2 - 80. This range may be even further limited to the range of 1.6 - 40 and selected according to the power supply requirements.
  • 1.6 - 8 It may be even further limited to the range of 1.6 - 8 and thus as an example have any of the values of 1.6, 3.1, 5.7 or 8 in order to provide a second voltage U2 of 50 kV, 70 kV, 130 kV or 245kV when the first voltage Ul is 400 kV. These specific voltages are suitable because they are standard values often used.
  • the first transformer 26 then transforms the second voltage U2 to an intermediate voltage, the third voltage U3, which in the first embodiment is a voltage of 10 kV.
  • This voltage is also a standard local power distribution system voltage.
  • standard transformers operating on the exemplifying second voltages U2 mentioned above and the exemplifying third voltage U3 of 10 kV are provided. These are readily available and a good selection when economy is of importance.
  • the value of the third voltage U3 is a mere example. This particular value is no requirement.
  • the third voltage U3 may for instance be in the range of 3 - 40 kV and thus be a fraction of the first voltage Ul, and the relationship that may be in the range of 1/266 - 1/8.
  • the second transformer 34 then transforms the third voltage U3 to the fourth voltage U4, which is a voltage required for the devices of the substation.
  • This fourth voltage U4 can as an example be 400 V, which is a type of voltage normally provided in a power distribution system or utility grid.
  • the group of reactive compensation elements 32 may also be selectively connected to the second power line 30 in order to perform reactive compensation of the load 36 and perhaps also voltage control.
  • the resistor 28 is here used for limiting the current in case of faults and may be omitted if this
  • compensation devices or filters for instance filters for filtering away harmonic components of the AC voltage of the first power line 10.
  • filters for instance filters for filtering away harmonic components of the AC voltage of the first power line 10.
  • the reactive voltage dividing elements are thus put to dual use, i.e. to both act as voltage dividing element and filter element.
  • the reactive voltage dividing elements may thus be part of a filter for filtering away frequency components that differ from the fundamental frequency of the AC voltage of the first power line.
  • the reactive power compensation elements were above described as being connected in a Y- connection in relation to the second power line. It should be realized that each group may here instead be connected in a delta-configuration. It is in fact possible that reactive compensation is not needed and therefore these elements may furthermore be completely omitted . It is also possible to omit the second transformer. If for instance the required power is so low that a low second voltage can be used, for instance a voltage of 1 kV in relation to the example of 400 kV, then it is possible to use only one transformer that directly converters from the second voltage to the fourth voltage .
  • each transformer may be Y-connected instead and/or the secondary winding of each transformer may be delta connected instead.
  • the invention may in fact be
  • the devices that need to be supplied with power can include control and protection computers for the valves. However the devices requiring most energy are normally devices used for cooling such as fans and pumps .
  • the substation is a substation lacking a transformer operating at the voltage of the first AC power line.
  • the power supply is a substation lacking a transformer operating at the voltage of the first AC power line.
  • the arrangement may also be combined with a transformer used in the transmission of power over this first AC power line without tapping off power from this power transmission transformer. This may be of interest when the configuration of the power supply transformer is to be different from the configuration of the power transmission transformer.
  • the power transmission transformer may in some instances require to have a delta-connection on the side facing the converter, which may give rise to problems when also tapping off power for power supply. This is avoided with the present solution, since the first transformer used in the power supply arrangement can be configured

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

Abstract

La présente invention concerne un agencement d'alimentation (18) pour un poste électrique, ledit agencement d'alimentation comprenant un groupe d'éléments diviseurs de tension réactifs (20, 22, 24) connectés à une première ligne électrique à courant alternatif (10) transportant du courant alternatif au poste électrique ou depuis ce dernier, et un premier transformateur (26) présentant un enroulement primaire (PW) et un enroulement secondaire (SW). L'enroulement primaire est connecté en parallèle à au moins un élément (24) des éléments diviseurs de tension et l'enroulement secondaire est couplé au poste électrique pour fournir du courant alternatif aux dispositifs d'alimentation (36) du poste électrique. Cet agencement permet des économies de coût par rapport aux transformateurs, en particulier à des tensions élevées.
PCT/EP2010/063615 2010-09-16 2010-09-16 Agencement d'alimentation pour poste électrique Ceased WO2012034593A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2010/063615 WO2012034593A1 (fr) 2010-09-16 2010-09-16 Agencement d'alimentation pour poste électrique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2010/063615 WO2012034593A1 (fr) 2010-09-16 2010-09-16 Agencement d'alimentation pour poste électrique

Publications (1)

Publication Number Publication Date
WO2012034593A1 true WO2012034593A1 (fr) 2012-03-22

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PCT/EP2010/063615 Ceased WO2012034593A1 (fr) 2010-09-16 2010-09-16 Agencement d'alimentation pour poste électrique

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2186486A (en) * 1939-07-08 1940-01-09 Ohio Brass Co Capactance potential device
FR1092040A (fr) * 1953-01-27 1955-04-18 Asea Ab Transformateur de tension du type à condensateurs
US3684948A (en) * 1971-02-08 1972-08-15 Gen Electric Potential device with input reactance adjustment
WO2004045046A1 (fr) * 2002-11-13 2004-05-27 Abb Ab Alimentation electrique auxiliaire

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2186486A (en) * 1939-07-08 1940-01-09 Ohio Brass Co Capactance potential device
FR1092040A (fr) * 1953-01-27 1955-04-18 Asea Ab Transformateur de tension du type à condensateurs
US3684948A (en) * 1971-02-08 1972-08-15 Gen Electric Potential device with input reactance adjustment
WO2004045046A1 (fr) * 2002-11-13 2004-05-27 Abb Ab Alimentation electrique auxiliaire

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