CN115621063A - Single-resistor transition circuit of converter transformer on-load voltage regulation switch and voltage regulation method - Google Patents
Single-resistor transition circuit of converter transformer on-load voltage regulation switch and voltage regulation method Download PDFInfo
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- CN115621063A CN115621063A CN202211407068.2A CN202211407068A CN115621063A CN 115621063 A CN115621063 A CN 115621063A CN 202211407068 A CN202211407068 A CN 202211407068A CN 115621063 A CN115621063 A CN 115621063A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
- H01H9/54—Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F29/00—Variable transformers or inductances not covered by group H01F21/00
- H01F29/02—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
- H01F29/04—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings having provision for tap-changing without interrupting the load current
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- 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
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- 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]
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Abstract
The invention discloses a single-resistor transition circuit of a converter transformer on-load tap changer and a voltage regulating method, wherein the single-resistor transition circuit comprises a first vacuum tube, a second vacuum tube, a third vacuum tube, a first change-over switch, a second change-over switch and a transition resistor, wherein a first main contact and the first vacuum tube are connected with a first winding tap of a voltage regulating winding of a transformer; the second main contact and the third vacuum tube are connected with a second winding tap of the transformer voltage-regulating winding; the first vacuum tube and the transition resistor are connected with a moving contact of the first change-over switch; the transition resistor and the other end of the third vacuum tube are connected with a moving contact of the second change-over switch. The invention adopts a transition resistor and three vacuum tubes, in the reciprocating switching process of a transition circuit, the second vacuum tube takes the task of switching on and off load current, and the first vacuum tube and the third vacuum tube take the task of alternately switching on and off interstage circulation current; the single transition resistor is used, so that the design and installation are convenient, and the insulation distance is ensured; the vacuum contact has the advantages of less transition resistance and alternate load bearing of the auxiliary vacuum contact.
Description
Technical Field
The invention relates to the technical field of on-load tap-changers, in particular to a single-resistor transition circuit of a converter transformer on-load voltage regulating switch and a voltage regulating method.
Background
The on-load tap-changer is a key component in the power transformer, can be operated under the excitation or load state of the transformer, and can change a plurality of taps led out from a connecting transformer winding to change the effective turn ratio, thereby realizing the regulation of output voltage under the condition of not interrupting load current. The on-load tap-changer has wide application range, and is particularly applied to a converter transformer of an extra-high voltage direct-current transmission project to ensure the rated trigger angle of a converter in normal operation. The on-load tap-changer equipped for the early power transformer mostly adopts the high-speed resistance switching principle and carries out load conversion by a copper-tungsten arc contact. The oil-immersed non-vacuum on-load tap-changer has frequent switching, correspondingly serious burning loss of an arc contact and high carbonization and pollution speed of oil, thereby increasing the workload of daily maintenance and regular overhaul for a power supply department. The vacuum type on-load tap-changer mainly uses a vacuum tube to realize arc extinguishing, thereby avoiding the carbonization and pollution of the arc extinguishing in oil; because the arc-breaking time of the vacuum tube is short, the arc voltage is low, the energy consumption of the electric arc is low, and the contact metal vapor is re-condensed, the burning loss and corrosion of the contact can be reduced to the minimum. The power electronic on-load tap changer replaces a vacuum tube by a power electronic element so as to realize the on-off arc operation in the on-load switching process.
The on-load tap-changer consists of a change-over switch, a tap selector and an electric mechanism. The transfer switch has an independent oil chamber, is a key component for realizing load transfer by the tap changer, and adopts a transition circuit at the core. The vacuum type on-load tap-changer can be divided into a single-contact circuit, a double-contact circuit, a three-contact circuit and a four-contact circuit according to different numbers of vacuum tubes; according to the number of transition resistors, the single resistor and the double resistor transition are adopted; single fracture, double fracture, etc. are formed according to the number of the contact fractures; the various combinations can form various vacuum type on-load tap-changer transition circuits. The vacuum tube in the transition circuit can be a single-break vacuum contact, a double-break vacuum contact, a power electronic element and the like; different switching sequences are provided for different transition circuits in order to realize on-load switching voltage regulation, and the switching tasks of the vacuum tubes are different. The topological structure of the transition circuit has obvious influence on the reliability of the on-load tap-changer switching process, the failure rate of the switch and the electrical service life.
The transition circuit of the on-load tap changer is provided with a main on-off vacuum tube which only undertakes the task of switching on and off load current and an auxiliary vacuum tube which only undertakes the task of switching on and off interstage circulation. In the actual extra-high voltage direct current transmission project, the load current flowing through the on-load tap changer of the converter transformer is about 500-600A, the interstage circulating current flowing through the transition resistor in the switching process is about 900-1000A, and the circulating current of the single on-off of the auxiliary vacuum tube is obviously larger than the load current of the on-off of the main on-off vacuum tube, so that the on-off task of the auxiliary vacuum tube and the main on-off vacuum tube is unbalanced. The on-load tap-changer usually adopts an oil-immersed mechanical contact change-over switch, and acts in the switching process, once timing sequence matching error occurs, the change-over switch is inevitably caused to extinguish arcs in oil, after the arcs are extinguished in the oil for many times, transformer oil is seriously polluted, carbon is produced and accumulated, the insulating property is reduced, and then the arcs in the oil cannot be extinguished, so that a great safety risk exists.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention aims to provide a single-resistor transition circuit of a converter transformer on-load tap-changer and a voltage regulating method.
The purpose of the invention is realized by the following technical scheme:
a single-resistor transition circuit of a converter transformer on-load tap changer comprises a first main contact, a second main contact, a first vacuum tube, a second vacuum tube, a third vacuum tube, a first change-over switch, a second change-over switch and a transition resistor;
one end of the first main contact and one end of the first vacuum tube are connected with a first winding tap of a transformer regulating winding; one end of the second main contact and one end of the third vacuum tube are connected with a second winding tap of the transformer voltage regulating winding;
the other end of the first vacuum tube and one end of the transition resistor are connected with a moving contact of the first change-over switch; the other end of the transition resistor and the other end of the third vacuum tube are connected with a moving contact of the second change-over switch;
the second fixed contact of the first change-over switch and the first fixed contact of the second change-over switch are connected with one end of the second vacuum tube; the first fixed contact of the first change-over switch and the second fixed contact of the second change-over switch are connected with a neutral point leading-out end of the on-load tap-changer; and the other ends of the first main contact, the second main contact and the second vacuum tube are connected with a neutral point leading-out end of the on-load tap-changer.
Further, when the first main contact, the first vacuum tube and the second vacuum tube are all in a conducting state, the third vacuum tube and the second main contact are in a disconnecting state, the moving contact of the first change-over switch is connected with the second fixed contact, and the moving contact of the second change-over switch is connected with the second fixed contact, the on-load tap-changer transition circuit enables load current to flow out from the neutral point leading-out end through the first main contact.
Further, when the second main contact, the second vacuum tube and the third vacuum tube are all in a conducting state, the first vacuum tube and the first main contact are in a disconnecting state, the moving contact of the first change-over switch is connected with the first fixed contact, and the moving contact of the second change-over switch is connected with the first fixed contact, the on-load tap-changer transition circuit enables load current to flow out from the neutral point leading-out end through the second main contact.
Furthermore, the first vacuum tube, the second vacuum tube and the third vacuum tube are single-break vacuum tubes, double-break vacuum tubes or power electronic elements with the function of controlling on-off.
A voltage regulation method based on a single-resistor transition circuit of a converter transformer on-load tap changer comprises the following steps:
the first main contact, the first vacuum tube and the second vacuum tube are all in a conducting state, the third vacuum tube and the second main contact are in a disconnecting state, the moving contact of the first change-over switch is connected with the second fixed contact, and the moving contact of the second change-over switch is connected with the second fixed contact;
disconnecting the second vacuum tube after the first main contact is disconnected; after the second vacuum tube is completely extinguished, the third vacuum tube is conducted, and the first winding tap and the second winding tap are in a bridging position; disconnecting the first vacuum tube; after the first vacuum tube is completely extinguished, the second main contact is conducted, and the load current flows out from the neutral point through the second main contact from the second winding tap;
after the third vacuum tube is disconnected, the moving contact of the first change-over switch is moved to the first fixed contact; moving a moving contact of the second change-over switch to the first fixed contact; and conducting the second vacuum tube and the third vacuum tube, and switching the on-load tap changer from the first winding tap to the second winding tap.
Further, when the first winding tap and the second winding tap are in the bridge position, the current flowing through the third vacuum tube is calculated by the following formula:
I V ＝I N -I C
wherein, I V For the current flowing through the third vacuum tube, I C The current flowing through the first vacuum tube is inter-stage circulation current I N Is the load current.
Further, the current flowing through the first vacuum tube is calculated as an interstage current flow by:
I C ＝U S /R
wherein, U S The voltage between the on-load tap-changer stages is R is transition resistance.
A voltage regulation method based on a single-resistor transition circuit of a converter transformer on-load tap changer comprises the following steps:
the second main contact, the second vacuum tube and the third vacuum tube are all in a conducting state, the first vacuum tube and the first main contact are in a disconnecting state, the moving contact of the first change-over switch is connected with the first fixed contact, and the moving contact of the second change-over switch is connected with the first fixed contact
Disconnecting the second vacuum tube after the second main contact is disconnected; after the second vacuum tube is completely extinguished, the first vacuum tube is conducted, and at the moment, the first winding tap and the second winding tap are in a bridging position, and the third vacuum tube is disconnected; after the third vacuum tube is completely extinguished, the first main contact is conducted, and load current flows out from the neutral point through the first winding tap and the first main contact;
after the first vacuum tube is disconnected, the moving contact of the first change-over switch is moved to the second fixed contact; moving a moving contact of the second change-over switch to a second fixed contact; conducting the second vacuum tube and the first vacuum tube; the on-load tap changer switches from the second winding tap to the first winding tap.
Further, when the first winding tap and the second winding tap are in the bridge position, the current flowing through the first vacuum tube is calculated by the following formula:
I V ＝I N +I C
wherein, I C The current flowing through the third vacuum tube is inter-stage circulation current I N Is the load current.
Further, the current flowing through the third vacuum tube is the inter-stage circulating current calculated by the following formula:
I C ＝U S /R
wherein, U S The voltage between the on-load tap-changer stages is R is transition resistance.
Compared with the prior art, the invention has the following beneficial effects:
the transition circuit adopts the transition resistor and the three vacuum tubes, the second vacuum tube bears the task of switching on and off load current in the reciprocating switching process of the on-load tap-changer, and the first vacuum tube and the third vacuum tube bear the task of switching on and off interstage circulation in turn, so that the switching loss of the interstage circulation vacuum tubes is reduced, the switching capacity of each vacuum tube is balanced, and the reliability and the service life of the on-load tap-changer are improved; the single transition resistor is used, so that the design and the installation are convenient, and the insulation distance is ensured; the vacuum contactor has the advantages of less transition resistance, alternative load bearing of the auxiliary vacuum contactor and high safety.
According to the voltage regulating method, in the through-current process of switching the load current from the main contact at one side to the main contact at the other side, the two change-over switches do not need to act, and the load current is switched after the switching process between the winding taps is finished, so that the condition that the arc is cut off by the change-over switches in the switching process is avoided, the degradation condition of insulating oil in the long-term service period of the on-load tap-changer is reduced, and the maintenance-free requirement of the service period of the on-load tap-changer is favorably met; the two change-over switches act simultaneously, so that the mechanical complexity of the on-load tap-changer can be effectively reduced, and the reliability of the on-load tap-changer is improved.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings:
fig. 1 is a circuit diagram of a single resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the invention;
fig. 2 is a schematic diagram of a switching process of a first main contact in a single resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a switching process of disconnection of a second vacuum tube in a single-resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the invention;
fig. 4 is a schematic diagram of a switching process of conduction of a third vacuum tube in a single-resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a switching process of disconnecting a first vacuum tube in a single resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a switching process of conduction of a second main contact in a single-resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a switching process of disconnecting a third vacuum tube in a single resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a switching process of actions of a first change-over switch and a second change-over switch in a single resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a switching process of conduction of a second vacuum tube and a third vacuum tube in a single-resistance transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 10 is a schematic diagram of on-off of each switch in a single-resistor transition circuit of a converter transformer on-load tap changing switch according to an embodiment of the present invention during a process of switching a load from a first winding tap N to a second winding tap N + 1;
fig. 11 is a schematic diagram of on-off of each switch in a single-resistor transition circuit of a converter transformer on-load tap changing switch according to an embodiment of the present invention during a process of switching a load from a second winding tap N +1 to a first winding tap N;
fig. 12 is a circuit diagram of a single resistance transition circuit of a converter transformer on-load tap changer in which the switching elements are power electronic elements according to an embodiment of the present invention;
fig. 13 is a circuit diagram of a single resistance transition circuit of a converter transformer on-load tap changer in which the switching element is a double break vacuum tube according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, the invention provides a single-resistor transition circuit of a converter transformer on-load tap changer and a voltage regulating method, wherein a transition resistor and three vacuum tubes are adopted, in the reciprocating switching process of the on-load tap changer transition circuit, a second vacuum tube V2 bears the task of switching on and off load current, and a first vacuum tube V1 and a third vacuum tube V3 bear the task of switching on and off inter-stage circulation in turn, so that the switching loss of the inter-stage circulation vacuum tubes is reduced, the switching capacity of each vacuum tube is balanced, and the reliability and the service life of the on-load tap changer are improved; two change-over switches are adopted, the two change-over switches do not need to act in the through-current process of switching the load current from a main contact on one side to a main contact on the other side, and the change-over action is carried out after the switching process of the load current is finished, so that the condition that the arc is cut off by the change-over switches in the switching process is avoided, and the fault possibility of the on-load tap-changer is reduced; the single transition resistor is used, so that the design and installation are convenient, and the insulation distance is ensured; the vacuum contact has the advantages of less transition resistance and alternate bearing of the auxiliary vacuum contact.
The single-resistor transition circuit of the converter transformer on-load tap changer comprises a first main contact MC1, a second main contact MC2, a first vacuum tube V1, a second vacuum tube V2, a third vacuum tube V3, a first change-over switch T1, a second change-over switch T2 and a transition resistor R; one end of the first main contact MC1 is connected with a first winding tap N of a transformer regulating winding; one end of the second main contact MC2 is connected with a second winding tap N +1 of the transformer regulating winding; one end of the first vacuum tube V1 is connected with a first winding tap N of a transformer voltage regulating winding, and the other end of the first vacuum tube V1 is connected with one end of a transition resistor R and a moving contact of a first change-over switch T1; one end of the transition resistor R is connected with one end of a first vacuum tube V1 and a moving contact of a first change-over switch T1, and the other end of the transition resistor R is connected with one end of a third vacuum tube V3 and a moving contact of a second change-over switch T2; one end of the third vacuum tube V3 is connected with a second winding tap N +1 of the transformer voltage-regulating winding, and the other end of the third vacuum tube V is connected with one end of the transition resistor R and a moving contact of the second change-over switch T2; one end of the second vacuum tube V2 is connected to the second stationary contact 12 of the first transfer switch T1 and the first stationary contact 21 of the second transfer switch; the first fixed contact 11 of the first change-over switch T1 and the second fixed contact 22 of the second change-over switch T2 are both connected with a neutral point leading-out end of the on-load tap-changer; the other ends of the first main contact MC1, the second main contact MC2 and the second vacuum tube V2 are connected with a neutral point leading-out end of the on-load tap-changer.
When the first main contact MC1, the first vacuum tube V1 and the second vacuum tube V2 are all in a conducting state, the third vacuum tube V3 and the second main contact MC2 are in a disconnecting state, the moving contact of the first change-over switch T1 is connected with the second fixed contact 12 thereof, and the moving contact of the second change-over switch T2 is connected with the second fixed contact 22 thereof, the on-load tap-changer transition circuit can enable a load current to flow out from the neutral leading-out end through the first main contact MC 1.
When the second main contact MC2, the second vacuum tube V2 and the third vacuum tube V3 are all in a conducting state, the first vacuum tube V1 and the first main contact MC1 are in a disconnecting state, the moving contact of the first change-over switch T1 is connected with the first fixed contact 11 thereof, and the moving contact of the second change-over switch T2 is connected with the first fixed contact 21 thereof, the on-load tap-changer transition circuit can enable a load current to flow out from the neutral leading-out end through the second main contact MC 2.
The internal switch elements in the single-resistor transition circuit of the converter transformer on-load voltage regulating switch, namely the first vacuum tube V1, the second vacuum tube V2 and the third vacuum tube V3, can be replaced by a power electronic element and a double-break vacuum tube with the function of controlling on-off from a single-break vacuum tube.
A voltage regulation method of a single-resistance transition circuit of a converter transformer on-load voltage regulation switch takes a single-fracture vacuum tube as an example; when the on-load tap-changer is switched from a first winding tap N to a second winding tap N +1, the voltage regulating method comprises the following steps:
as shown in fig. 1, the first main contact MC1 is in a conducting state, the second main contact MC2 is in a disconnecting state, the first vacuum tube V1 and the second vacuum tube V2 are in a conducting state, the third vacuum tube V3 is in a disconnecting state, the moving contact of the first transfer switch T1 is connected with the second stationary contact 12 thereof, and the moving contact of the second transfer switch T2 is connected with the second stationary contact 22 thereof. The first winding tap N is switched on and the load current flows out of the neutral point outlet through the first main contact MC 1.
As shown in fig. 2, the first main contact MC1 is disconnected, the second main contact MC2 is kept disconnected, the first vacuum tube V1 and the second vacuum tube V2 are kept on, the third vacuum tube V3 is kept disconnected, the movable contact of the first change-over switch T1 is connected with the second fixed contact 12, the movable contact of the second change-over switch T2 is connected with the second fixed contact 22, the first winding tap N is continuously connected, and the load current flows out from the neutral point leading-out end through the first vacuum tube V1, the second vacuum tube V2 and the first change-over switch T1.
As shown in fig. 3, the first main contact MC1 is kept off, the second main contact MC2 is kept off, the second vacuum tube V2 is disconnected, an arc is generated, the first vacuum tube V1 is kept on, the movable contact of the first change-over switch T1 is connected with the second fixed contact 12, the movable contact of the second change-over switch T2 is connected with the second fixed contact 22, the first winding tap N is continuously connected, and the load current flows out from the neutral point leading-out terminal through the first vacuum tube V1, the transition resistor R and the second change-over switch T2.
As shown in fig. 4, the first main contact MC1 is kept open, the second main contact MC2 is kept open, the second vacuum tube V2 is kept open, after the second vacuum tube V2 is completely extinguished, the third vacuum tube V3 is closed, the movable contact of the first transfer switch T1 is connected to the second stationary contact 12 thereof, the movable contact of the second transfer switch T2 is connected to the second stationary contact 22 thereof, the first winding tap N and the second winding tap N +1 are both connected, and the load current I is applied N Flows out from the neutral point leading-out end through a third vacuum tube V3 and a second change-over switch T2; the transition circuit forms a bridge connection, namely the first winding tap N and the second winding tap N +1 are in a bridge connection position to generate an inter-stage circulation current I C (ii) a The current flowing through the first vacuum tube V1 is interstage annular current I C Current I flowing through the third vacuum tube V3 V3 ＝I N -I C (ii) a Wherein I C ＝U S R, said U S Is the voltage between the on-load tap-changer stages.
As shown in fig. 5, the first main contact MC1 is kept off, the second main contact MC2 is kept off, the first vacuum tube V1 is disconnected, an arc is generated, the second vacuum tube V2 is kept off, the third vacuum tube V3 is kept on, the movable contact of the first change-over switch T1 is connected with the second fixed contact 12 thereof, the movable contact of the second change-over switch T2 is connected with the second fixed contact 22 thereof, the second winding tap N +1 is connected, and the load current flows out from the neutral point leading-out end through the third vacuum tube V3 and the second change-over switch T2.
As shown in fig. 6, the first main contact MC1 is kept open, after the first vacuum tube V1 is completely extinguished, the second main contact MC2 is closed, the first vacuum tube V1 and the second vacuum tube V2 are kept open, the third vacuum tube V3 is kept on, the movable contact of the first transfer switch T1 is connected to the second fixed contact 12 thereof, the movable contact of the second transfer switch T2 is connected to the second fixed contact 22 thereof, the second winding tap N +1 is connected, and the load current flows out from the neutral point leading-out end through the second main contact MC 2.
As shown in fig. 7, the first main contact MC1 is kept off, the second main contact MC2 is kept on, the first vacuum tube V1 and the second vacuum tube V2 are kept off, the third vacuum tube V3 is disconnected, the movable contact of the first transfer switch T1 is connected to the second fixed contact 12 thereof, the movable contact of the second transfer switch T2 is connected to the second fixed contact 22 thereof, the second winding tap N +1 is continuously switched on, and the load current flows out from the neutral point leading-out end through the second main contact MC 2.
As shown in fig. 8, the first main contact MC1 is kept off, the second main contact MC2 is kept on, the first vacuum tube V1, the second vacuum tube V2 and the third vacuum tube V3 are kept off, the movable contact of the first transfer switch T1 is connected to the first fixed contact 11 thereof, the movable contact of the second transfer switch T2 is connected to the first fixed contact 21 thereof, the second winding tap N +1 is continuously turned on, and the load current flows out from the neutral point leading-out end through the second main contact MC 2.
As shown in fig. 9, the first main contact MC1 is kept off, the second main contact MC2 is kept on, the first vacuum tube V1 is kept off, the second vacuum tube V2 and the third vacuum tube V3 are conducted, the movable contact of the first transfer switch T1 is connected to the first fixed contact 11 thereof, the movable contact of the second transfer switch T2 is connected to the first fixed contact 21 thereof, the second winding tap N +1 is continuously connected, and the load current flows out from the neutral point leading-out end through the second main contact MC 2.
When the on-load tap-changer is switched from the second winding tap N +1 to the first winding tap N, the switching process is symmetrical to the switching process of the on-load tap-changer from the first winding tap N to the second winding tap N +1, and the voltage regulating method comprises the following steps:
the second main contact MC2 is in a conducting state, the first main contact MC1 is in a disconnecting state, the third vacuum tube V3 and the second vacuum tube V2 are in a conducting state, the first vacuum tube V1 is in a disconnecting state, the moving contact of the first change-over switch T1 is connected with the first fixed contact 11, and the moving contact of the second change-over switch T2 is connected with the first fixed contact 21. The second winding tap N +1 is switched on and the load current flows out of the neutral point outlet through the second main contact MC 2.
The second main contact MC2 is disconnected, the first main contact MC1 is kept disconnected, the third vacuum tube V3 and the second vacuum tube V2 are kept conducted, the first vacuum tube V1 is kept disconnected, the moving contact of the first change-over switch T1 is connected with the first fixed contact 11, the moving contact of the second change-over switch T2 is connected with the first fixed contact 21, the second winding tap N +1 is continuously connected, and the load current flows out from the neutral point leading-out end through the third vacuum tube V3, the second vacuum tube V2 and the second change-over switch T2.
The second main contact MC2 is kept to be disconnected, the first main contact MC1 is kept to be disconnected, the second vacuum tube V2 is disconnected, an electric arc is generated, the third vacuum tube V3 is kept to be conducted, the moving contact of the first change-over switch T1 is connected with the first fixed contact 11, the moving contact of the second change-over switch T2 is connected with the first fixed contact 21, the second winding tap N +1 is continuously conducted, and load current flows out from the neutral point leading-out end through the third vacuum tube V3, the second change-over switch T2 and the transition resistor R.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the second vacuum tube V2 is kept disconnected, after the second vacuum tube V2 is completely extinguished, the first vacuum tube V1 is closed, the movable contact of the first change-over switch T1 is connected with the first fixed contact 11, the movable contact of the second change-over switch T2 is connected with the first fixed contact 21, the first winding tap N and the second winding tap N +1 are both switched on, and the load current I is N Flows out from the neutral point leading-out end through a first vacuum tube V1 and a first change-over switch T1; the transition circuit forms a bridge connection to generate an inter-stage circulating current I C (ii) a The current flowing through the third vacuum tube V3 is interstage circulating current I C Current I flowing through the first vacuum tube V1 V1 ＝I N +I C (ii) a Wherein I C ＝U S R, said U S Is the voltage between the on-load tap-changer stages.
The second main contact MC2 keeps off, the first main contact MC1 keeps off, the third vacuum tube V3 is disconnected, an electric arc is generated, the second vacuum tube V2 keeps off, the first vacuum tube V1 keeps on, the moving contact of the first change-over switch T1 is connected with the first fixed contact 11, the moving contact of the second change-over switch T2 is connected with the first fixed contact 21, the first winding tap N is connected, and the load current flows out from the neutral point leading-out end through the first vacuum tube V1 and the first change-over switch T1.
The second main contact MC2 keeps being disconnected, after the third vacuum tube V3 is completely extinguished, the first main contact MC1 is closed, the third vacuum tube V3 and the second vacuum tube V2 keep being disconnected, the first vacuum tube V1 keeps being conducted, the moving contact of the first change-over switch T1 is connected with the first fixed contact 11 thereof, the moving contact of the second change-over switch T2 is connected with the first fixed contact 21 thereof, the first winding tap N is connected, and the load current flows out from the neutral point leading-out end through the first main contact MC 1.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept conducted, the third vacuum tube V3 and the second vacuum tube V2 are kept disconnected, the first vacuum tube V1 is disconnected, the movable contact of the first change-over switch T1 is connected with the first fixed contact 11, the movable contact of the second change-over switch T2 is connected with the first fixed contact 21, the first winding tap N is continuously connected, and the load current flows out from the neutral leading-out end through the first main contact MC 1.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept conducted, the third vacuum tube V3, the second vacuum tube V2 and the first vacuum tube V1 are kept disconnected, the movable contact of the first change-over switch T1 is connected with the second fixed contact 12, the movable contact of the second change-over switch T2 is connected with the second fixed contact 22, the first winding tap N is continuously connected, and the load current flows out from the neutral leading-out end through the first main contact MC 1.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept conducted, the third vacuum tube V3 is kept disconnected, the second vacuum tube V2 and the first vacuum tube V1 are conducted, the movable contact of the first change-over switch T1 is connected with the second fixed contact 12, the movable contact of the second change-over switch T2 is connected with the second fixed contact 22, the first winding tap N is continuously connected, and the load current flows out from the neutral leading-out end through the first main contact MC 1.
When the internal switch elements in the single-resistor transition circuit of the converter transformer on-load voltage regulation switch are power electronic elements and double-break vacuum tubes with the on-off controllable function, the action time sequence of the switch elements is consistent with the voltage regulation method, and the description is omitted.
When the on-load tap changer switches from a first winding N tap to a second winding N +1 tap, the transition circuit switching process is as shown in fig. 10.
When the on-load tap changer switches from the second winding N +1 tap to the first winding N tap, the transition circuit switching process is as shown in fig. 11.
In an embodiment of the invention, the switching tasks of the on-load tap changer transition circuit using vacuum tubes are as follows:
wherein, I N Is the load current; u shape S Is the voltage between the on-load tap-changer stages; and R is transition resistance.
Fig. 12 is a circuit diagram of a single-resistor transition circuit of a converter transformer on-load tap changer in which a switching element is a power electronic element according to an embodiment of the present invention, and as shown in fig. 12, only the single-break vacuum tube in fig. 1 is replaced with a power electronic element with a controllable on-off function, and other elements are the same as those in fig. 1, and the operation timing sequence is the same, and the function and function of the transition circuit shown in fig. 1 are also the same, and are not described again here.
FIG. 13 is a circuit diagram of a single resistance transition circuit of a converter transformer on-load tap changer with a switching element of a double break vacuum tube according to an embodiment of the present invention; as shown in fig. 13, only the single-break vacuum tube in fig. 1 is replaced by a double-break vacuum tube, and other elements are the same as those in fig. 1, and the action timing is the same, and the function and function of the transition circuit shown in fig. 1 are also the same, which are not described again here.
The transition circuit of the invention adopts a transition resistor and three vacuum tubes, in the reciprocating switching process of the transition circuit, the second vacuum tube V2 takes on the task of switching off load current, and the first vacuum tube V1 and the third vacuum tube V3 take on the task of switching off interstage circulation in turn; the single transition resistor is used, so that the design and the installation are convenient, and the insulation distance is ensured; the vacuum contact has the advantages of less transition resistance and alternate load bearing of the auxiliary vacuum contact.
The above description is only for the best embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention, such as adding a disconnecting switch to the existing circuit of the vacuum tube for electrical isolation and protection, should be covered within the scope of the present invention.
Claims (10)
1. A single-resistor transition circuit of a converter transformer on-load tap changer is characterized by comprising a first main contact (MC 1), a second main contact (MC 2), a first vacuum tube (V1), a second vacuum tube (V2), a third vacuum tube (V3), a first change-over switch (T1), a second change-over switch (T2) and a transition resistor (R);
one end of the first main contact (MC 1) and one end of the first vacuum tube (V1) are connected with a first winding tap (N) of a transformer regulating winding; one end of the second main contact (MC 2) and one end of the third vacuum tube (V3) are connected with a second winding tap (N + 1) of the transformer voltage-regulating winding;
the other end of the first vacuum tube (V1) and one end of the transition resistor (R) are connected with a moving contact of the first change-over switch (T1); the other end of the transition resistor (R) and the other end of the third vacuum tube (V3) are connected with a moving contact of a second change-over switch (T2);
a second fixed contact (12) of the first change-over switch (T1) and a first fixed contact (21) of the second change-over switch are connected with one end of a second vacuum tube (V2); a first fixed contact (11) of the first change-over switch (T1) and a second fixed contact (22) of the second change-over switch (T2) are connected with a neutral point leading-out end of the on-load tap-changer; the other ends of the first main contact (MC 1), the second main contact (MC 2) and the second vacuum tube (V2) are connected with a neutral point leading-out end of the on-load tap-changer.
2. The single-resistor transition circuit of the converter transformer on-load tap changer according to claim 1, wherein when the first main contact (MC 1), the first vacuum tube (V1), and the second vacuum tube (V2) are all in a conducting state, the third vacuum tube (V3) and the second main contact (MC 2) are in a disconnecting state, the moving contact of the first transfer switch (T1) is connected with the second fixed contact (12), and the moving contact of the second transfer switch (T2) is connected with the second fixed contact (22), the on-load tap changer transition circuit enables a load current to flow out from the neutral point outlet through the first main contact (MC 1).
3. The single-resistor transition circuit of the converter transformer on-load tap changer according to claim 1, wherein when the second main contact (MC 2), the second vacuum tube (V2), and the third vacuum tube (V3) are all in a conducting state, the first vacuum tube (V1) and the first main contact (MC 1) are in a disconnecting state, the moving contact of the first transfer switch (T1) is connected with the first fixed contact (11), and the moving contact of the second transfer switch (T2) is connected with the first fixed contact (21), the on-load tap changer transition circuit enables a load current to flow out from the neutral point outlet through the second main contact (MC 2).
4. The single-resistor transition circuit of the converter transformer on-load tap changer according to claim 1, wherein the first vacuum tube (V1), the second vacuum tube (V2) and the third vacuum tube (V3) are single-break vacuum tubes, double-break vacuum tubes or power electronic components with controllable on-off function.
5. The voltage regulation method of the single-resistor transition circuit of the converter transformer on-load tap changer based on claim 1 is characterized by comprising the following steps:
the first main contact (MC 1), the first vacuum tube (V1) and the second vacuum tube (V2) are all in a conducting state, the third vacuum tube (V3) and the second main contact (MC 2) are in a disconnecting state, a moving contact of the first change-over switch (T1) is connected with the second fixed contact (12), and a moving contact of the second change-over switch (T2) is connected with the second fixed contact (22);
disconnecting the second vacuum tube (V2) after disconnecting the first main contact (MC 1); after the second vacuum tube (V2) is completely extinguished, the third vacuum tube (V3) is conducted, and at the moment, the first winding tap (N) and the second winding tap (N + 1) are in a bridging position; disconnecting the first vacuum tube (V1); after the first vacuum tube (V1) is completely extinguished, the second main contact (MC 2) is conducted, and load current flows out from the neutral point through the second main contact (MC 2) from the second winding tap (N + 1);
after the third vacuum tube (V3) is disconnected, the moving contact of the first change-over switch (T1) is moved to the first fixed contact (11); moving a moving contact of a second change-over switch (T2) to a first fixed contact (21); and (3) conducting the second vacuum tube (V2) and the third vacuum tube (V3), and switching the on-load tap changer from the first winding tap (N) to the second winding tap (N + 1).
6. The method for regulating voltage in a single resistance transition circuit of a converter transformer on-load tap changer according to claim 5, characterized in that when the first winding tap (N) and the second winding tap (N + 1) are in the bridging position, the current flowing through the third vacuum tube (V3) is calculated by the following formula:
I V ＝I N -I C
wherein, I V Is the current flowing through the third vacuum tube, I C The current flowing through the first vacuum tube is inter-stage circulation current I N Is the load current.
7. The method for regulating the voltage of the single-resistor transition circuit of the converter transformer on-load tap changer of claim 6, wherein the current flowing through the first vacuum tube is the inter-stage circulating current calculated by the following formula:
I C ＝U S /R
wherein, U S The voltage between the on-load tap-changer stages is R is transition resistance.
8. The voltage regulation method of the single-resistor transition circuit of the converter transformer on-load tap changer based on claim 1 is characterized by comprising the following steps:
the second main contact (MC 2), the second vacuum tube (V2) and the third vacuum tube (V3) are all in a conducting state, the first vacuum tube (V1) and the first main contact (MC 1) are in a disconnecting state, the moving contact of the first change-over switch (T1) is connected with the first fixed contact (11), and the moving contact of the second change-over switch (T2) is connected with the first fixed contact (21)
Disconnecting the second vacuum tube (V2) after the second main contact (MC 2) is disconnected; after the second vacuum tube (V2) is completely extinguished, the first vacuum tube (V1) is conducted, and at the moment, the first winding tap (N) and the second winding tap (N + 1) are in a bridging position; disconnecting the third vacuum tube (V3); after the third vacuum tube (V3) is completely extinguished, the first main contact (MC 1) is conducted, and load current flows out from the neutral point through the first main contact (MC 1) from the first winding tap (N);
after the first vacuum tube (V1) is disconnected, the moving contact of the first change-over switch (T1) is moved to the second fixed contact (12); moving a moving contact of a second change-over switch (T2) to a second fixed contact (22); conducting a second vacuum tube (V2) and a first vacuum tube (V1); the on-load tap changer switches from the second winding tap (N + 1) to the first winding tap (N).
9. The method for regulating voltage of a single resistance transition circuit of a converter transformer on-load tap changer according to claim 7, wherein when the first winding tap (N) and the second winding tap (N + 1) are in the bridging position, the current flowing through the first vacuum tube (V1) is calculated by the following formula:
I V ＝I N +I C
wherein, I C The current flowing through the third vacuum tube is inter-stage circulation current I N Is the load current.
10. The method for regulating the voltage of the single-resistor transition circuit of the converter transformer on-load tap changer according to claim 9, wherein the current flowing through the third vacuum tube is the inter-stage circulating current calculated by the following formula:
I C ＝U S /R
wherein, U S The voltage between the on-load tap-changer stages is R, and the transition resistance is R.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211407068.2A CN115621063A (en) | 2022-11-10 | 2022-11-10 | Single-resistor transition circuit of converter transformer on-load voltage regulation switch and voltage regulation method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211407068.2A CN115621063A (en) | 2022-11-10 | 2022-11-10 | Single-resistor transition circuit of converter transformer on-load voltage regulation switch and voltage regulation method |
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| CN202211407068.2A Pending CN115621063A (en) | 2022-11-10 | 2022-11-10 | Single-resistor transition circuit of converter transformer on-load voltage regulation switch and voltage regulation method |
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