CA1146628A - Voltage-measuring device for controlling the rectifiers of current-converters in high- voltage direct-current transmission systems - Google Patents
Voltage-measuring device for controlling the rectifiers of current-converters in high- voltage direct-current transmission systemsInfo
- Publication number
- CA1146628A CA1146628A CA000354851A CA354851A CA1146628A CA 1146628 A CA1146628 A CA 1146628A CA 000354851 A CA000354851 A CA 000354851A CA 354851 A CA354851 A CA 354851A CA 1146628 A CA1146628 A CA 1146628A
- Authority
- CA
- Canada
- Prior art keywords
- current
- voltage
- converter
- mains
- winding
- 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.)
- Expired
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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
- G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
- G01R15/185—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core with compensation or feedback windings or interacting coils, e.g. 0-flux sensors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils
- H01F27/422—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers
- H01F27/425—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers for voltage transformers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/22—Instruments transformers for single phase ac
- H01F38/24—Voltage 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
- 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]
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Rectifiers (AREA)
- Transformers For Measuring Instruments (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In a device for establishing a phase-correct representation of a high alternating voltage from a mains, for the purpose of controlling mains-operated rectifiers (valves) of a current-converter-connected to the mains through a current-converter-transformer, in a high-voltage direct-current trans-mission system, an auxiliary winding is provided in the current-converter-trans-former.
In a device for establishing a phase-correct representation of a high alternating voltage from a mains, for the purpose of controlling mains-operated rectifiers (valves) of a current-converter-connected to the mains through a current-converter-transformer, in a high-voltage direct-current trans-mission system, an auxiliary winding is provided in the current-converter-trans-former.
Description
6~13 ~ liS invention relates to a device for establishing a correct-phase representation of a high alternating mains voltage for controlling mains-operated rectifiers of a current-converter connected to the mains, through a current-converter-transformer~ in a high-voltage direct-current transmission system.
In controlling mains-operated current-converters, it is necessary, in order to determine the firing time of the rectifiers, to have available a correct-phase representation of the mains-voltage of about the order of 100 to 380 V at ground potential. Up to a maximal mains-voltage of 220 kV, inductive voltage-transformers of conventional design may be used economically.
At higher voltages, however, such transformers are unavailable be-cause of the excessive cost of high-voltage insulation. Instead of these there are capacitative transformers, the specifications for which are given, for example, in regulations VDE 0414 of the Association of German Electrotech-nicians ~VDE). These, however, have only a certain class accuracy as regards fundamental voltage oscillation, which is quite sufficient when used for cost-ing purposes.
In the case of high-voltage direct-current transmission, the vol-tage of the connected alternating-current mains is usually higher than 220 kV.
However, capacitative transformers, which are suitable from the voltage point of view, are unsuitable for producing the representation necessary for control-ling the current-converter rectifiers since, as a result of the frequency-res-ponse of the said transformers, the secondary voltage is incorrect as regards amount and phase-position, because of unavoidable harmonics.
It is obvious to connect the voltage-transformer or transformers of conventional design to the secondary side of the current-converter-trans-former. This voltage, however, is also still very high and, depending upon the ~,.
.r~q~ .
62~
location of the current-converter-transformer within the pole system, it has a direct-voltage component which is a multiple of the line-voltage to ground.
It is the purpose of the invention to provide a means whereby a phase-correct representation of the mains-voltage can be obtained even above 220 kV, at low cost and in compact form.
According to the invention there is provided a device for estab-lishing a correct-phase representation of a high alternating mains voltage for controlling mains-operated rectifiers of a current-converter connected to the mains, through a current-converter-transformer, in a high-voltage direct-current transmission system, said transformer having a magnetic core, at least one primary winding adapted to be connected to the mains, at least one secondary winding and an auxiliary winding arranged to be influenced by magnetic flux produced by the primary winding.
The invention takes advantage of the knowledge that the iron core and reservoir of the current-converter-transformer are already at ground po-tential, so that the necessary representation-voltage, at the correct level and potential, may be obtained by means of the auxiliary winding without ap-preciable expenditure on insulation. The device may thus be produced inex-pensively, since very-high voltage lead-throughs may be eliminated. The measurement already provides a criterion of rectifier-voltage, without tne usual need to take into account the setting of the current-converter-trans-former tapping switch. Furthermore, less room is required in the system and additional insulated sections, which may give rise to breakdowns, are elimin-ated.
Advantageous developments of the invention are described hereinafter.
In many cases, the primary-side neutral point ~star-point) of the current-collverter-transformer is rigidly grounded. In these cases, it is preferable to dispense with a separate auxiliary windi.ng. Instead, the inner portion of the primary winding, near to ground, is brought out in (low-power) taps.
~Yhere separate auxiliary windings are used, the neutral point, and -2a-in tlle case of single-phase units, one end of the auxiliary winding, is con-nected directly to the core of the current-converter-transformer, which elimin-ates one or three lead-throughs.
Since the auxiliary winding is not protected against short-circuits by the primary switch on the current-converter--transformer, it must be pro-tected by secondary-side cut-outs, in which case the unprotected line should be as short as possible. This is best accomplished by connecting each cut-out directly to the auxiliary winding.
In order to prevent, or compensate for, transformer failures caused by unavoidable stray fluxes in the current-converter-transformer, the auxiliary winding should be linked as closely as possible to the primary flux. This pos-sibility is restricted in practice to avoiding secondary stray flux, which means arranging the auxiliary winding as directly as possible on the core. Faults, which still arise as a result of stray primary voltage, may be reduced to a minimum by making available an additional voltage proportional to the current variations (di/dt) and adding it to the voltage taken from the auxiliary wind-ing.
The invention is explained hereinafter in conjunction with the examples of embodiment illustrated in the drawing attached hereto, wherein:
Figures 1 to 3 illustrate diagramatically various arrangements of the auxiliary winding in the current-converter-transormer, and;
Figure 4 is an equivalent circuit-diagram with an auxiliary device.
According to Figure 1, a current-converter-transformer comprises a laminated, grounded iron-core 1 in a reservoir 2, filled with insulating oil, for example, and with insulated lead-throughs 5 in the wall of the said reser-voir. Core 1, fitted with high-voltage insulation 7, carries a (primary) winding 3 connected to a high-voltage a.c. mains and a (secondary) winding 4 6;~8 connected to a current-converter, not shown.
According to the invention, core 1 also carries, with no need for high-voltage insulation, an auxiliary winding 6, connections 11 to which are led out of the reservoir. One of these connections runs to a cut-out device 8 incorporated directly into auxiliary winding 6, while the other connection is grounded externally of reservoir 2. If no ground-connection is provided, the second connection should also run to a cut-out device.
Auxiliary winding 6 is arranged in such a manner as to comprise a magnetic flux which is as close as possible to the flux produced by mains vol-tage Ul by means of winding 3. ~his makes it possible, at no great cost, totake off, at auxiliary-winding connections 11, at ground potential, a phase-correct representation of high mains voltage U1J which may be used to control the rectifiers ~valves) of the current converter connected to winding 4.
According to Figure 2, auxiliary winding 6 is in the form of a tap 9 at the rigidly grounded neutral point of mains-side current-converter-transformer winding 3, located between phase-voltage R and neutral point 0.
I-lere again the connections to auxiliary winding 6 are marked 11.
In Figure 3, one end of separately arranged auxiliary winding 6 is connected directly to grounded core 1 of the current-converter-transformer.
In the case of the single-phase unit shown, this despenses with the need for a lead-through for second connection 11.
Figure 4 is the usual equivalent circuit-diagram for a transformer, without taking ohmic resistances into account. The primary-side leakage-inductance L of winding 3 is marked 13, the secondary-side leakage-inductance of winding 4 is marked 14, and the coupling inductance is marked 15. The mains voltage is marked Ul, the current-converter-side voltage is marked U2, and the magnetizing voltage is marked UFE. The secondary-side current converter, :1:14~6Z~
comlected to the currcnt-converter-transformer, i.s marked 16.
Even with a favourable arrangement of auxiliary winding 6, whereby the secondary leakage-flux of the current-converter transformer may be disre-garded in establishing the representation of the mains voltage, it may be ne-cessary to compensate for measurement errors because of the primary side leak-age flux.
This compensation is provided by a supplementary device 12 which makes available a voltage proportional to the inductive-voltage drop in the mains-side winding (L.di/dt). This current-proportional voltage is then added to the (measuring) voltage at connections 11 of auxiliary winding 6. In order to produce this current-proportional voltage, primary-side current il is fed, through a current-transformer 17, to supplementary device 12 which is preferably a differentiator.
In controlling mains-operated current-converters, it is necessary, in order to determine the firing time of the rectifiers, to have available a correct-phase representation of the mains-voltage of about the order of 100 to 380 V at ground potential. Up to a maximal mains-voltage of 220 kV, inductive voltage-transformers of conventional design may be used economically.
At higher voltages, however, such transformers are unavailable be-cause of the excessive cost of high-voltage insulation. Instead of these there are capacitative transformers, the specifications for which are given, for example, in regulations VDE 0414 of the Association of German Electrotech-nicians ~VDE). These, however, have only a certain class accuracy as regards fundamental voltage oscillation, which is quite sufficient when used for cost-ing purposes.
In the case of high-voltage direct-current transmission, the vol-tage of the connected alternating-current mains is usually higher than 220 kV.
However, capacitative transformers, which are suitable from the voltage point of view, are unsuitable for producing the representation necessary for control-ling the current-converter rectifiers since, as a result of the frequency-res-ponse of the said transformers, the secondary voltage is incorrect as regards amount and phase-position, because of unavoidable harmonics.
It is obvious to connect the voltage-transformer or transformers of conventional design to the secondary side of the current-converter-trans-former. This voltage, however, is also still very high and, depending upon the ~,.
.r~q~ .
62~
location of the current-converter-transformer within the pole system, it has a direct-voltage component which is a multiple of the line-voltage to ground.
It is the purpose of the invention to provide a means whereby a phase-correct representation of the mains-voltage can be obtained even above 220 kV, at low cost and in compact form.
According to the invention there is provided a device for estab-lishing a correct-phase representation of a high alternating mains voltage for controlling mains-operated rectifiers of a current-converter connected to the mains, through a current-converter-transformer, in a high-voltage direct-current transmission system, said transformer having a magnetic core, at least one primary winding adapted to be connected to the mains, at least one secondary winding and an auxiliary winding arranged to be influenced by magnetic flux produced by the primary winding.
The invention takes advantage of the knowledge that the iron core and reservoir of the current-converter-transformer are already at ground po-tential, so that the necessary representation-voltage, at the correct level and potential, may be obtained by means of the auxiliary winding without ap-preciable expenditure on insulation. The device may thus be produced inex-pensively, since very-high voltage lead-throughs may be eliminated. The measurement already provides a criterion of rectifier-voltage, without tne usual need to take into account the setting of the current-converter-trans-former tapping switch. Furthermore, less room is required in the system and additional insulated sections, which may give rise to breakdowns, are elimin-ated.
Advantageous developments of the invention are described hereinafter.
In many cases, the primary-side neutral point ~star-point) of the current-collverter-transformer is rigidly grounded. In these cases, it is preferable to dispense with a separate auxiliary windi.ng. Instead, the inner portion of the primary winding, near to ground, is brought out in (low-power) taps.
~Yhere separate auxiliary windings are used, the neutral point, and -2a-in tlle case of single-phase units, one end of the auxiliary winding, is con-nected directly to the core of the current-converter-transformer, which elimin-ates one or three lead-throughs.
Since the auxiliary winding is not protected against short-circuits by the primary switch on the current-converter--transformer, it must be pro-tected by secondary-side cut-outs, in which case the unprotected line should be as short as possible. This is best accomplished by connecting each cut-out directly to the auxiliary winding.
In order to prevent, or compensate for, transformer failures caused by unavoidable stray fluxes in the current-converter-transformer, the auxiliary winding should be linked as closely as possible to the primary flux. This pos-sibility is restricted in practice to avoiding secondary stray flux, which means arranging the auxiliary winding as directly as possible on the core. Faults, which still arise as a result of stray primary voltage, may be reduced to a minimum by making available an additional voltage proportional to the current variations (di/dt) and adding it to the voltage taken from the auxiliary wind-ing.
The invention is explained hereinafter in conjunction with the examples of embodiment illustrated in the drawing attached hereto, wherein:
Figures 1 to 3 illustrate diagramatically various arrangements of the auxiliary winding in the current-converter-transormer, and;
Figure 4 is an equivalent circuit-diagram with an auxiliary device.
According to Figure 1, a current-converter-transformer comprises a laminated, grounded iron-core 1 in a reservoir 2, filled with insulating oil, for example, and with insulated lead-throughs 5 in the wall of the said reser-voir. Core 1, fitted with high-voltage insulation 7, carries a (primary) winding 3 connected to a high-voltage a.c. mains and a (secondary) winding 4 6;~8 connected to a current-converter, not shown.
According to the invention, core 1 also carries, with no need for high-voltage insulation, an auxiliary winding 6, connections 11 to which are led out of the reservoir. One of these connections runs to a cut-out device 8 incorporated directly into auxiliary winding 6, while the other connection is grounded externally of reservoir 2. If no ground-connection is provided, the second connection should also run to a cut-out device.
Auxiliary winding 6 is arranged in such a manner as to comprise a magnetic flux which is as close as possible to the flux produced by mains vol-tage Ul by means of winding 3. ~his makes it possible, at no great cost, totake off, at auxiliary-winding connections 11, at ground potential, a phase-correct representation of high mains voltage U1J which may be used to control the rectifiers ~valves) of the current converter connected to winding 4.
According to Figure 2, auxiliary winding 6 is in the form of a tap 9 at the rigidly grounded neutral point of mains-side current-converter-transformer winding 3, located between phase-voltage R and neutral point 0.
I-lere again the connections to auxiliary winding 6 are marked 11.
In Figure 3, one end of separately arranged auxiliary winding 6 is connected directly to grounded core 1 of the current-converter-transformer.
In the case of the single-phase unit shown, this despenses with the need for a lead-through for second connection 11.
Figure 4 is the usual equivalent circuit-diagram for a transformer, without taking ohmic resistances into account. The primary-side leakage-inductance L of winding 3 is marked 13, the secondary-side leakage-inductance of winding 4 is marked 14, and the coupling inductance is marked 15. The mains voltage is marked Ul, the current-converter-side voltage is marked U2, and the magnetizing voltage is marked UFE. The secondary-side current converter, :1:14~6Z~
comlected to the currcnt-converter-transformer, i.s marked 16.
Even with a favourable arrangement of auxiliary winding 6, whereby the secondary leakage-flux of the current-converter transformer may be disre-garded in establishing the representation of the mains voltage, it may be ne-cessary to compensate for measurement errors because of the primary side leak-age flux.
This compensation is provided by a supplementary device 12 which makes available a voltage proportional to the inductive-voltage drop in the mains-side winding (L.di/dt). This current-proportional voltage is then added to the (measuring) voltage at connections 11 of auxiliary winding 6. In order to produce this current-proportional voltage, primary-side current il is fed, through a current-transformer 17, to supplementary device 12 which is preferably a differentiator.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for establishing a correct-phase representation of a high alternating mains voltage for controlling mains-operated rectifiers of a cur-rent-converter connected to the mains, through a current-converter-transformer, in a high-voltage direct-current transmission system, said transformer having a magnetic core, at least one primary winding adapted to be connected to the mains, at least one secondary winding and an auxiliary winding arranged to be influenced by magnetic flux produced by the primary winding.
2. A device according to claim 1, wherein the current-converter-trans-former has a rigidly grounded neutral point and the auxiliary winding is in the form of a tap at a neutral point of the primary winding.
3. A device according to claim 1, characterized in that one end of the auxiliary winding is connected directly to a grounded core of the current-converter-transformer.
4. A device according to claim 1, 2 or 3, characterized in that one of the connections on the auxiliary winding is connected directly to a cut-out device incorporated directly into said auxiliary winding.
5. A device according to one of claims 1 or 3, characterized in that magnetic flux in the auxiliary winding is substantially the same as the flux produced by the mains voltage.
6. A device according to claims 1, 2 or 3, characterized by a supple-mentary device which provides compensation for inductive voltage drop in the primary winding.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792926423 DE2926423A1 (en) | 1979-06-27 | 1979-06-27 | VOLTAGE MEASURING DEVICE FOR VALVE CONTROL OF RECTIFIERS IN HGUE SYSTEMS |
| DEP2926423.1 | 1979-06-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1146628A true CA1146628A (en) | 1983-05-17 |
Family
ID=6074564
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000354851A Expired CA1146628A (en) | 1979-06-27 | 1980-06-26 | Voltage-measuring device for controlling the rectifiers of current-converters in high- voltage direct-current transmission systems |
Country Status (7)
| Country | Link |
|---|---|
| AT (1) | AT374984B (en) |
| BR (1) | BR8004002A (en) |
| CA (1) | CA1146628A (en) |
| CH (1) | CH651703A5 (en) |
| DE (1) | DE2926423A1 (en) |
| SE (1) | SE8004787L (en) |
| ZA (1) | ZA803754B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE9319889U1 (en) * | 1993-12-23 | 1995-05-04 | Siemens AG, 80333 München | Series circuit transformer |
| US9947450B1 (en) | 2012-07-19 | 2018-04-17 | The Boeing Company | Magnetic core signal modulation |
| US9568563B2 (en) | 2012-07-19 | 2017-02-14 | The Boeing Company | Magnetic core flux sensor |
| US9455084B2 (en) | 2012-07-19 | 2016-09-27 | The Boeing Company | Variable core electromagnetic device |
| US9389619B2 (en) | 2013-07-29 | 2016-07-12 | The Boeing Company | Transformer core flux control for power management |
| US9159487B2 (en) | 2012-07-19 | 2015-10-13 | The Boeing Company | Linear electromagnetic device |
| US9651633B2 (en) | 2013-02-21 | 2017-05-16 | The Boeing Company | Magnetic core flux sensor |
| EP2840675B1 (en) * | 2013-08-08 | 2018-11-14 | The Boeing Company | Electrical power distribution network monitoring and control |
| US10403429B2 (en) | 2016-01-13 | 2019-09-03 | The Boeing Company | Multi-pulse electromagnetic device including a linear magnetic core configuration |
-
1979
- 1979-06-27 DE DE19792926423 patent/DE2926423A1/en not_active Ceased
-
1980
- 1980-06-24 ZA ZA00803754A patent/ZA803754B/en unknown
- 1980-06-25 BR BR8004002A patent/BR8004002A/en unknown
- 1980-06-26 CH CH4931/80A patent/CH651703A5/en not_active IP Right Cessation
- 1980-06-26 AT AT0335480A patent/AT374984B/en not_active IP Right Cessation
- 1980-06-26 CA CA000354851A patent/CA1146628A/en not_active Expired
- 1980-06-27 SE SE8004787A patent/SE8004787L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| SE8004787L (en) | 1980-12-28 |
| BR8004002A (en) | 1981-01-21 |
| DE2926423A1 (en) | 1981-01-08 |
| CH651703A5 (en) | 1985-09-30 |
| ATA335480A (en) | 1983-10-15 |
| AT374984B (en) | 1984-06-25 |
| ZA803754B (en) | 1981-06-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |