GB2459764A - DC power transmission system - Google Patents

DC power transmission system Download PDF

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Publication number
GB2459764A
GB2459764A GB0907505A GB0907505A GB2459764A GB 2459764 A GB2459764 A GB 2459764A GB 0907505 A GB0907505 A GB 0907505A GB 0907505 A GB0907505 A GB 0907505A GB 2459764 A GB2459764 A GB 2459764A
Authority
GB
United Kingdom
Prior art keywords
voltage
limiting
limiting filter
smoothing inductor
converter
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Withdrawn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
GB0907505A
Other versions
GB0907505D0 (en
Inventor
Sven Achenbach
Juergen Rittiger
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.)
Siemens AG
Original Assignee
Siemens 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 Siemens AG filed Critical Siemens AG
Publication of GB0907505D0 publication Critical patent/GB0907505D0/en
Publication of GB2459764A publication Critical patent/GB2459764A/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • 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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/02—Arrangements for reducing harmonics or ripples
    • 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
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
    • 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
    • H02J2003/365—Reducing harmonics or oscillations in HVDC
    • 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]

Abstract

Apparatus (1) for the transmission of electrical power includes a first converter (2), which is designed for conversion of an AC voltage to a DC voltage, which is connected via a DC voltage connection (4) to a second converter for conversion of the DC voltage to an AC voltage. A smoothing inductor LG is designed to smooth the DC voltage, and a limiting filter (9) limits an AC component in the DC voltage connection (4). A part of the smoothing inductor LG is used as part of the limiting filter (9), so that a separate additional limiting inductor in the limiting filter (9) is no longer required.

Description

Apparatus for transmission of electrical power The invention relates to an apparatus for the transmission of electrical power having a first converter which is designed for conversion of an AC voltage to a DC voltage; a smoothing inductor LG, which is designed to smooth the DC voltage; and a limiting filter in order to limit an AC component in the DC voltage connection. The first converter is designed to be connected in use via a DC voltage connection to at least one second converter for conversion of the DC voltage back to an AC voltage.
One such apparatus is already known from the prior art and is normally referred to as a high-voltage DC transmission (HVDCT) installation. Figure 1 schematically illustrates one such already known apparatus. The apparatus 1 shown there comprises a rectifier 2 as the first converter, which is connected via a transformer 3 to an AC voltage or three-phase network, which is not illustrated in the figure. The rectifier is designed to convert the AC voltage, which is fed in from the AC voltage network via the transformer 3, to a DC voltage, and is connectable via a DC voltage connection 4 to an inverter, which is not illustrated in figure 1, as the second converter. The inverter is connected via a further transformer to a further AC -voltage network, to which the loads to be supplied are coupled.
An HVDCT installation such as this allows electrical power to be transmitted at low cost over long distances, since DC voltage transmission is subject to less loss than AC voltage transmission.
The DC voltage connection 4 is in the form of a single-pole DC voltage connection in figure 1. In other words, only one transmission line 5 is provided between the converters. A smoothing inductor LG is arranged in the DC voltage line 5 in order to smooth the DC voltage, and comprises two DC inductor sections 7 and 8. In the case of single-pole installations, the DC circuit is closed via a ground connection. A grounding electrode, which is not illustrated in figure 1 but is connected via a ground connecting line 6 to a second DC voltage connection of the respective converter, is used to ground the converters.
In the case of HVDCT installations, disadvantageous resonance conditions can occur depending on the topology of the DC voltage circuit, of the AC voltage filters and of the short-circuit power of the connected AC voltage networks.
Low-impedance resonant points in the DC voltage connection may occur at harmonics of the fundamental frequency of the connected AC voltage networks. Typical and practically relevant cases are low-impedance resonant points at the fundamental or at the second harmonic of the fundamental, with respect to the fundamental frequency of the connected AC voltage networks.
Imbalances in the apparatus, which are generally always present in practice, can result in excessively high undesirable harmonic currents in the DC voltage connection in certain system states which either are not suppressed at all or are only inadequately suppressed by the filters provided in the apparatus. The filters provided are generally designed for the characteristic harmonics of the fundamental frequency of the connected AC voltage networks that occur on conversion, that is to say for higher frequencies. Since said AC components in the apparatus shown in figure 1 according to the prior art would exceed permissible limit values, a limiting filter 9 is provided in order to limit or suppress said AC components. The limiting filter 9 is arranged in the ground connecting line 6 and comprises a limiting inductance L5 and a limiting capacitance Cs connected in parallel with it, with the limiting capacitance C5 being connected in series with a limiting resistor R. Additional components, for example a limiting filter such as this, increase the costs of the apparatus 1, however.
It is therefore desirable to provide an apparatus of the type mentioned initially, which costs little, and in which undesirable AC components in the DC voltage connection are suppressed at the same time.
The invention is defined in the independent claims, to which reference should now be made. Advantageous embodiments are set out in the sub claims.
In embodiments of the invention, the smoothing inductor is at least partially comprised as part of the limiting filter. That is, at least part of or at least one section of the smoothing inductor is comprised within the limiting filter, or in other words is a component of the limiting filter.
Thus, according to invention embodiments, at least part of the smoothing inductor is also used at the same time to suppress undesirable AC components in the DC voltage connection. For the purpose of the invention embodiments, a separate additional limiting inductor in the limiting filter has therefore become superfluous. Furthermore, the power losses are reduced, and the operating costs are therefore also reduced.
The limiting filter is advantageously tuned to at least one frequency of the AC component to be limited. This frequency is normally a harmonic of the fundamental of the AC voltage network that is connected to the respective converter, with said harmonic being of a low order, for example 2-4. To this end, the limiting filter advantageously comprises an induction coil and a limiting capacitance. If required, a limiting resistor is also provided. The limiting capacitance is, for example, a capacitor, a super-cap or the like. The limiting resistor is advantageously a resistor without reactance.
The limiting filter expediently has a parallel branch, which is arranged in parallel with at least one section of the smoothing inductor and in which a smoothing capacitance is connected. If required, a limiting resistor is provided in addition to the limiting capacitance. The limiting resistor is advantageously connected in parallel with the limiting capacitance, for example in a third branch. According to one arrangement of the invention, which differs from this, the limiting resistor is likewise connected in the parallel branch, and is therefore arranged in series with the limiting capacitance in the parallel branch.
The smoothing inductor advantageously comprises a plurality of smoothing inductor sections. In this case, the entire smoothing inductor is designed overall for smoothing the direct current.
One of the smoothing inductor sections or else a plurality of smoothing inductor sections including potentially the whole inductance/all the sections is furthermore used at the same time to limit the undesirable AC components in the DC voltage connection. One important factor for the purposes of the invention is that the smoothing inductor section is also taken into account at the same time in the design of the smoothing inductor, as a result of which it produces its effect both for smoothing of the DC component and for suppression of the undesirable AC component. The smoothing inductor section is therefore in any case part of the apparatus according to the invention embodiments, in conjunction with DC smoothing, which means that no additional limiting inductor, coil or inductance is required, despite the limiting filter.
According to one preferred arrangement, the smoothing inductor section, which is part of the limiting filter, is arranged in a ground connecting line which connects a grounding electrode to one of the converters. In other words, the limiting filter is arranged with the smoothing inductor section, which provides two effects -as described above -in the so-called neutral bus, and with normal operating parameters, is at a medium-voltage potential, that is to say between 1kV and 50kv.
According to one preferred arrangement, the DC voltage connection is a bipolar DC voltage connection and has a positive and a negative pole. In the case of bipolar DC voltage connections or apparatuses, as well, it is advantageous for each converter to be connected to a grounding electrode via a ground connecting line. Thus, if one pole of the DC voltage connection fails, current can flow to ground, thus preventing a total failure of the apparatus.
According to one further development, which is expedient in this context, each pole of the DC voltage connection has an associated limiting filter.
Further expedient arrangements and advantages of the invention are the subject matter of the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, in which the same reference symbols refer to components having the same effect, and in which: figure 1 shows an apparatus according to the
prior art,
figure 2 shows one exemplary embodiment of the apparatus according to the invention, figure 3 shows a further exemplary embodiment of the apparatus according to the invention, figure 4 shows a further exemplary embodiment of the apparatus according to the invention, and figure 5 shows a further exemplary embodiment of the apparatus according to the invention.
Figure 1 shows an apparatus according to the prior art, which has already been described at the start of this application, as a result of which there is no need for a detailed description at this point.
Figure 2 shows one exemplary embodiment of the apparatus 1 according to the invention, which has a rectifier 2 as the first converter as well as an inverter which is not illustrated in the figure, as the second converter, with the two converters being connectable to one another via a DC voltage connection 4.
Each converter is connected on the AC voltage side to an AC voltage or three-phase network, with a transformer 3 ensuring galvanic isolation between the AC voltage network and the converter. The transformer 3 comprises a primary winding 10 and two secondary windings 11 and 12, which are each connected to one AC voltage connection of the rectifier 2. A different connection of the secondary windings results in a phase shift, as a result of which a so-called twelve-pulse converter is provided by two series-connected six-pulse bridge circuits of the current valves, which twelve-pulse converter is known per se to a person skilled in the art, so that its design and method of operation will not be described in any more detail at this point.
The single-pole DC voltage connection 4 in the illustrated exemplary embodiment has only one DC voltage line 5, with the DC circuit 4 being closed via a ground path. As is normal in the prior art, a grounding electrode, which is not illustrated in figure 2 but is connected via a ground connecting line 6 to one of the DC voltage connections of the rectifier 2, is used to provide a reliable ground path. The inverter, which is not illustrated, is correspondingly grounded. A smoothing inductor, the totality of which is annotated with LG in figure 2, is used to smooth the direct current. The smoothing inductor LG has two smoothing inductor sections 7 and 8, which are connected in series with one another. The smoothing inductor sections 7 and 8 are designed such that, in total, they provide the desired smoothing of the direct current. The smoothing inductor section 8 is furthermore part of a limiting filter 9, which is used to suppress undesirable AC components in the DC voltage connection 4.
In addition to the smoothing inductor section 8, that is to say the inductance LG2, the limiting filter 9 has a parallel branch 13 in which a limiting capacitance C and a limiting resistor Rs are connected in series.
Figure 3 shows a further exemplary embodiment of the apparatus 1 according to the invention, which differs from the exemplary embodiment shown in figure 2 in that the limiting resistor R3 is not arranged in the parallel branch 13 in which the limiting capacitance is connected. In fact, the limiting resistor Rs is arranged both in parallel with the smoothing inductor section 8 and in parallel with the limiting capacitance Cs.
Figure 4 shows a further exemplary embodiment of the apparatus 1 according to the invention, which corresponds to the exemplary embodiment shown in figure 2 in terms of the design of the limiting filter 9. However, in the case of the exemplary embodiment shown in figure 4, the limiting filter 9 is not arranged in the connecting line 5 of the DC voltage connection 4 but in the ground connecting line 6, which connects the rectifier 2, as the first converter, to the grounding electrode, which is not illustrated in the figure.
Figure 5 shows a further exemplary embodiment of the apparatus 1 according to the invention, in which the design of the limiting filter 9 corresponds to the exemplary embodiment shown in figure 3. However, corresponding to figure 4, the limiting filter 9 is once again arranged in the ground connecting line 6.
Finally, it should be noted that the inverter, which is not illustrated but can be included in some invention embodiments, can be designed in the same way as the rectifier described here and can likewise have a limiting filter 9. The limiting filter 9 of the inverter is designed, for example, in the same way as the limiting filter illustrated in figures 2 to 5.

Claims (11)

  1. Claims 1. An apparatus for the transmission of electrical power having; a first converter which is designed for conversion of an AC voltage to a DC voltage; a smoothing inductor LG, which is designed to smooth the DC voltage; and a limiting filter in order to limit an AC component in the DC voltage connection; wherein at least part of the smoothing inductor LG is part of the limiting filter.
  2. 2. The apparatus as claimed in claim 1, wherein the limiting filter is tuned to at least one frequency of the AC component to be limited.
  3. 3. The apparatus as claimed in either of claims 1 or 2, wherein the limiting filter has a parallel branch, which is arranged in parallel with at least one section of the smoothing inductor L and in which a smoothing capacitance L5 is connected.
  4. 4. The apparatus as claimed in claim 3, wherein a limiting resistor R5 is arranged in parallel with the limiting capacitance Cs.
  5. 5. The apparatus as claimed in claim 3, wherein a limiting resistor Rs is connected in the parallel branch.
  6. 6. The apparatus as claimed in any of the preceding claims, wherein the smoothing inductor LG comprises a plurality of smoothing inductor sections.
  7. 7. The apparatus as claimed in claim 6, -10 -wherein a smoothing inductor section, which is part of the limiting filter, is arranged in a ground connecting line which connects a grounding electrode to one of the converters.
  8. 8. The apparatus as claimed in any of the preceding claims, wherein the DC voltage connection is a bipolar DC voltage connection and has a positive pole and a negative pole.
  9. 9. The apparatus as claimed in claim 8, wherein each pole of the DC voltage connection has an associated limiting filter.
  10. 10. The apparatus of any of the preceding claims wherein the first converter is connected via a DC voltage connection to at least one second converter for conversion of the DC voltage to an AC voltage.
  11. 11. An apparatus for transmission of electrical power substantially according to an embodiment set out in thedescription and/or shown in any of Figures 2 to 5.
GB0907505A 2008-05-06 2009-04-30 DC power transmission system Withdrawn GB2459764A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102008022737 2008-05-06

Publications (2)

Publication Number Publication Date
GB0907505D0 GB0907505D0 (en) 2009-06-10
GB2459764A true GB2459764A (en) 2009-11-11

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GB0907505A Withdrawn GB2459764A (en) 2008-05-06 2009-04-30 DC power transmission system

Country Status (3)

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JP (1) JP2009273355A (en)
CN (1) CN101577501A (en)
GB (1) GB2459764A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011127983A1 (en) * 2010-04-15 2011-10-20 Abb Research Ltd Modular multi -level power converter with second and third order harmonics reduction filter
WO2011127984A1 (en) * 2010-04-15 2011-10-20 Abb Research Ltd Modular multi -level power converter with harmonics reduction and dc blocking filter
WO2012003857A1 (en) 2010-07-05 2012-01-12 Abb Research Ltd Interface arrangement between ac and dc systems
US8787042B2 (en) 2011-03-03 2014-07-22 Hitachi, Ltd. DC power supply including arrangement to reduce switching loss and a snubber circuit to suppress surge voltages
US8964414B2 (en) 2011-05-25 2015-02-24 Hitachi, Ltd. DC power supply including resonant circuit for reducing switching losses
WO2015055255A1 (en) * 2013-10-18 2015-04-23 Siemens Aktiengesellschaft Method and circuit for eliminating harmonic interference in dc transmission line
WO2015172825A1 (en) * 2014-05-14 2015-11-19 Abb Technology Ltd Ac fault handling arrangement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2013343524B2 (en) 2012-11-07 2017-05-25 Abb Schweiz Ag System with a first electric motor and a second electric motor for driving a line section

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4247888A (en) * 1978-07-03 1981-01-27 Asea Aktiebolag Static convertor apparatus
EP0146726A1 (en) * 1983-11-09 1985-07-03 Siemens Aktiengesellschaft Method and device for the operation of a HVDC transmission system with advanced phase control of the converters
EP0654883A1 (en) * 1993-11-19 1995-05-24 Asea Brown Boveri Ab High-voltage filter for filtering of harmonics in an electric power network

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4247888A (en) * 1978-07-03 1981-01-27 Asea Aktiebolag Static convertor apparatus
EP0146726A1 (en) * 1983-11-09 1985-07-03 Siemens Aktiengesellschaft Method and device for the operation of a HVDC transmission system with advanced phase control of the converters
EP0654883A1 (en) * 1993-11-19 1995-05-24 Asea Brown Boveri Ab High-voltage filter for filtering of harmonics in an electric power network

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011127983A1 (en) * 2010-04-15 2011-10-20 Abb Research Ltd Modular multi -level power converter with second and third order harmonics reduction filter
WO2011127984A1 (en) * 2010-04-15 2011-10-20 Abb Research Ltd Modular multi -level power converter with harmonics reduction and dc blocking filter
US8564981B2 (en) 2010-04-15 2013-10-22 Abb Research Ltd. Modular multi-level power converter with second and third order harmonics reduction filter
WO2012003857A1 (en) 2010-07-05 2012-01-12 Abb Research Ltd Interface arrangement between ac and dc systems
US8787042B2 (en) 2011-03-03 2014-07-22 Hitachi, Ltd. DC power supply including arrangement to reduce switching loss and a snubber circuit to suppress surge voltages
US8964414B2 (en) 2011-05-25 2015-02-24 Hitachi, Ltd. DC power supply including resonant circuit for reducing switching losses
WO2015055255A1 (en) * 2013-10-18 2015-04-23 Siemens Aktiengesellschaft Method and circuit for eliminating harmonic interference in dc transmission line
WO2015172825A1 (en) * 2014-05-14 2015-11-19 Abb Technology Ltd Ac fault handling arrangement

Also Published As

Publication number Publication date
GB0907505D0 (en) 2009-06-10
CN101577501A (en) 2009-11-11
JP2009273355A (en) 2009-11-19

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