CN115763112A - Symmetrical reciprocating transition circuit and voltage regulating method for converter transformer on-load voltage regulating switch - Google Patents
Symmetrical reciprocating transition circuit and voltage regulating method for converter transformer on-load voltage regulating switch Download PDFInfo
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Abstract
The invention discloses a symmetrical reciprocating transition circuit of a converter transformer on-load tap changer and a voltage regulating method, comprising the following steps: the vacuum circuit 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, a first transition resistor and a second transition resistor. Three vacuum tubes, two transition resistors and two change-over switches are adopted in the transition circuit, in the reciprocating switching process of the transition circuit, the second vacuum tube takes the task of switching off load current, and the first vacuum tube and the third vacuum tube take the task of switching off inter-stage circulation in turn; the transition circuit can bear a symmetrical and reciprocating switching time sequence, the action time sequence of the element is in mirror symmetry, and the mechanical complexity of the on-load tap-changer can be effectively reduced.
Description
Technical Field
The invention relates to the technical field of on-load tap-changers, in particular to a symmetrical reciprocating 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 and changed to connect a plurality of taps led out from a transformer winding to change the effective turn ratio under the excitation or load state of the transformer, and realizes 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 converter transformers in extra-high voltage direct current transmission projects to ensure the rated trigger angle of a converter in normal operation. The on-load tap-changer equipped with 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 on-off arcing 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-changer and an electric mechanism. The transfer switch is provided with an independent oil chamber, is a key component for realizing on-load switching of the tap switch, 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, a single resistor and a double resistor are used for transition; single fracture, double fracture and the like 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 comprises a main on-off vacuum tube which only bears the task of switching on/off load current and an auxiliary vacuum tube which only bears the task of switching on/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 ring current flowing through the transition resistor in the switching process is about 900-1000A, and the ring current of the auxiliary vacuum tube which is cut off at a single time is obviously larger than the load current 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 existing vacuum type on-load tap-changer transition circuit is asymmetric in control time sequence of switching from a winding tap N to a winding tap N +1 and switching from the winding tap N +1 to the winding tap N, and in the process of mechanical reciprocating motion of a switching core, a cam mechanism needs to realize rail lifting and rail changing, so that the complexity of mechanical manufacturing and the failure rate of switch use are increased.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention aims to provide a symmetrical reciprocating transition circuit of a converter transformer on-load tap changer and a voltage regulating method, wherein the transition circuit can bear a symmetrical reciprocating time sequence, the action time sequences of elements of the mechanical on-load tap changer adopting the voltage regulating method are in mirror symmetry in the forward and reverse reciprocating switching process, a mechanical rail transfer mechanism is not needed, and the mechanical complexity of the on-load tap changer can be effectively reduced.
In order to achieve the purpose, the invention adopts the following technical scheme:
a symmetrical reciprocating 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, a first transition resistor and a second 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, one end of the second vacuum tube and one end of the first transition resistor are connected with a first fixed contact of the first change-over switch; the other end of the third vacuum tube, the other end of the second vacuum tube and one end of the second transition resistor are connected with a first fixed contact of the second change-over switch; the other end of the first transition resistor is connected with a second fixed contact of the first change-over switch; the other end of the second transition resistor is connected with a second fixed contact of the second change-over switch; the other end of the first main contact, the other end of the second main contact, the moving contact of the first change-over switch and the moving contact of the second change-over switch are all 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 in a conducting state, the second main contact and the third vacuum tube 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 first fixed contact, the load current flows 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 in a conducting state, the first main contact and the first vacuum tube 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 second fixed contact, the load current flows 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 symmetrical reciprocating 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 second main contact and the third vacuum tube are all 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 first fixed contact;
disconnecting the second vacuum tube after the first main contact is disconnected, and connecting the moving contact of the second change-over switch with the second static contact after the second vacuum tube is completely extinguished;
after the third vacuum tube is conducted, the first winding tap and the second winding tap are located at a bridging position, the first vacuum tube is disconnected, and after the first vacuum tube is completely extinguished, the moving contact of the first change-over switch is connected with the first fixed contact;
and after the second vacuum tube is conducted, the second main contact is conducted, the load current flows out from the neutral point through the second main contact from the second winding tap, and the on-load tap-changer is switched from the first winding tap to the second winding tap.
Further, when the first winding tap and the second winding tap are in a bridging position, the current I flowing through the first vacuum tube V1 ＝I N /2+I C Current I flowing through the third vacuum tube V3 ＝I N /2-I C ；
Wherein, I N Is a load current, I C Is an interstage loop current.
Further, inter-stage circulating current I C ＝U S /(R1 + R2), wherein, U S For the on-load tap-changer stage voltage, R1 is a first transition resistor, and R2 is a second transition resistor.
A voltage regulation method based on a symmetrical reciprocating 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 in a conducting state, the first main contact and the first vacuum tube 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 second fixed contact;
disconnecting the second vacuum tube after the second main contact is disconnected, and connecting the moving contact of the first change-over switch with the second fixed contact after the second vacuum tube is completely extinguished;
after the first vacuum tube is conducted and the third vacuum tube is completely extinguished, the moving contact of the second change-over switch is connected with the first fixed contact;
and after the second vacuum tube is conducted, the first main contact is conducted, the load current flows out from the neutral point through the first main contact from the first winding tap, and the on-load tap-changer is switched from the second winding tap to the first winding tap.
Compared with the prior art, the invention has the following beneficial effects:
the transition circuit adopts three vacuum tubes, two transition resistors and two change-over switches, and the double transition resistors can effectively limit the interstage circulating current in the switching process and reduce the heating of the resistors; the auxiliary vacuum tubes are used for switching on and off interstage circulation, the second vacuum tube bears the task of switching on and off load current, and the first vacuum tube and the third vacuum tube bear the task of switching on and off interstage circulation current in turn, so that the switching loss of the auxiliary vacuum tubes is reduced, and the switching capacity among the vacuum tubes is balanced; the transition circuit is capable of carrying symmetrically reciprocating timing.
The voltage regulating method can ensure that the action programs of all switch elements are completely mirror-symmetrical in the reciprocating switching process of the transition circuit from the first winding tap N to the second winding tap N +1 and from the second winding tap N +1 to the first winding tap N, so that a track changing mechanism is not required to be adopted in the reciprocating mechanical structure of the on-load tap-changer, the mechanical complexity of the on-load tap-changer can be obviously reduced, and the long-term reliability of the on-load tap-changer in a service cycle 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 symmetrical reciprocating 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 conduction of a first main contact in a symmetrical reciprocating 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 a first main contact in a symmetrical reciprocating transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a switching process of disconnecting a second vacuum tube in a symmetrical reciprocating 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 a second change-over switch action in a symmetrical reciprocating 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 third vacuum tube in a symmetrical reciprocating 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 disconnection of a first vacuum tube in a symmetrical reciprocating transition circuit of a converter transformer on-load tap changer according to an embodiment of the invention;
fig. 8 is a schematic diagram of a switching process of a first switch action in a symmetrical reciprocating 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 in a symmetrical reciprocating 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 a switching process of conduction of a second main contact in a symmetrical reciprocating transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention;
fig. 11 is a schematic diagram of on-off of each switch in a symmetrical reciprocating 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 winding tap N to a winding tap N + 1;
fig. 12 is a schematic diagram of on-off of each switch in a symmetrical reciprocating transition circuit of a converter transformer on-load tap changer according to an embodiment of the present invention during a process of switching a load from a winding tap N +1 to a winding tap N;
fig. 13 is a circuit diagram of a symmetrical reciprocating 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 invention;
fig. 14 is a circuit diagram of a symmetrical reciprocating 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 invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1, the symmetrical reciprocating transition circuit of the converter transformer on-load tap changer includes 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 transfer switch T1, a second transfer switch T2, a first transition resistor R1 and a second transition resistor R2;
one end of the first main contact MC1 and one end of the first vacuum tube V1 are connected with a first winding tap N of a transformer voltage-regulating winding; one end of the second main contact MC2 and one end of the third vacuum tube V3 are connected with a second winding tap N +1 of the transformer regulating winding; the other end of the first vacuum tube V1, one end of the second vacuum tube V2 and one end of the first transition resistor R1 are connected with a first fixed contact 11 of the first transfer switch T1; the other end of the third vacuum tube V3, the other end of the second vacuum tube V2 and one end of the second transition resistor R2 are connected with a first fixed contact 21 of the second change-over switch; the other end of the first transition resistor R1 is connected to the second stationary contact 12 of the first transfer switch T1; the other end of the second transition resistor R2 is connected to the second stationary contact 22 of the second transfer switch T2; the other end of the first main contact MC1, the other end of the second main contact MC2, the moving contact of the first change-over switch T1 and the moving contact of the second change-over switch T2 are all 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 second main contact MC2 and the third vacuum tube V3 are all 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 first fixed contact 21 thereof, the on-load tap-changer transition circuit can enable a load current to flow out from the neutral point 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 main contact MC1 and the first vacuum tube V1 are all 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 second fixed contact 22 thereof, the on-load tap-changer transition circuit can enable a load current to flow out from the neutral point leading-out end through the second main contact MC 2.
Internal switch elements in the on-load tap-changer double-resistor symmetrical reciprocating transition circuit, namely a first vacuum tube V1, a second vacuum tube V2 and a third vacuum tube V3, can be replaced by a double-fracture vacuum tube or a power electronic element with a controllable on-off function from a single-fracture vacuum tube.
A voltage regulation method of a symmetrical reciprocating transition circuit of a converter transformer on-load tap changer 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 regulation method is as follows:
as shown in fig. 2, 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 to the second fixed contact 12 thereof, and the moving contact of the second transfer switch T2 is connected to the first fixed contact 21 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. 3, the first main contact MC1 is disconnected, the second main contact MC2 is disconnected, the first vacuum tube V1 and the second vacuum tube V2 are connected, the third vacuum tube V3 is disconnected, the moving contact of the first transfer switch T1 is connected to the second stationary contact 12, and the moving contact of the second transfer switch T2 is connected to the first stationary contact 21. The first winding tap N is continuously switched on, 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 second change-over switch T2.
As shown in fig. 4, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept disconnected, the first vacuum tube V1 is kept on, the second vacuum tube V2 is disconnected, an electric arc is generated, the third vacuum tube V3 is kept disconnected, the moving contact of the first transfer switch T1 is connected to the second fixed contact 12 thereof, and the moving contact of the second transfer switch T2 is connected to the first fixed contact 21 thereof. The first winding tap N is continuously switched on, and the load current flows out from the neutral point leading-out end through the first vacuum tube V1, the first transition resistor R1 and the first change-over switch T1.
As shown in fig. 5, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept disconnected, the first vacuum tube V1 is kept on, the second vacuum tube V2 and the third vacuum tube V3 are kept disconnected, the moving contact of the first transfer switch T1 is connected with the second stationary contact 12 thereof, and after the second vacuum tube V2 is completely extinguished, the moving contact of the second transfer switch T2 is connected with the second stationary contact 22 thereof. The first winding tap N is continued to be switched on and the load current I N Flows out from the neutral point leading-out end through the first vacuum tube V1, the first transition resistor R1 and the first change-over switch T1.
As shown in fig. 6, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept disconnected, the first vacuum tube V1 is kept conducted, the second vacuum tube V2 is kept disconnected, the third vacuum tube V3 is conducted, the movable contact of the first transfer switch T1 is connected to the second stationary contact 12 thereof, and 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 switched on, the load current I N Respectively flows out from the neutral point leading-out end through a first vacuum tube V1, a first transition resistor R1, a first change-over switch T1, a third vacuum tube V3, a second transition resistor R2 and a second change-over switch T2; the transition circuit forms a bridge connection to generate an inter-stage circulating current I C (ii) a Current I flowing through the first vacuum tube V1 V1 ＝I N /2+I C Current I flowing through the third vacuum tube V3 V3 ＝I N /2-I C (ii) a Wherein I C ＝U S /(R1 + R2), said U S Is an on-load tap-changer level voltage.
As shown in fig. 7, the first main contact MC1 is kept open, the second main contact MC2 is kept open, the first vacuum tube V1 is disconnected, an arc is generated, the second vacuum tube V2 is kept open, the third vacuum tube V3 is kept on, the moving contact of the first transfer switch T1 is connected to the second stationary contact 12 thereof, and the moving contact of the second transfer switch T2 is connected to the second stationary contact 22 thereof. And 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 third vacuum tube V3, the second transition resistor R2 and the second change-over switch T2.
As shown in fig. 8, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept disconnected, the first vacuum tube V1 and the second vacuum tube V2 are kept disconnected, the third vacuum tube V3 is kept conducted, after the first vacuum tube V1 is completely extinguished, the movable contact of the first transfer switch T1 is connected to the first fixed contact 11 thereof, and the movable contact of the second transfer switch T2 is connected to the second fixed contact 22 thereof. And the tap N +1 of the second winding is continuously switched on, and the load current flows out from the neutral point leading-out end through the third vacuum tube V3, the second transition resistor R2 and the second change-over switch T2.
As shown in fig. 9, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept disconnected, the first vacuum tube V1 is kept disconnected, the second vacuum tube V2 is conducted, the third vacuum tube V3 is kept conducted, the movable contact of the first transfer switch T1 is connected with the first fixed contact 11 thereof, and the movable contact of the second transfer switch T2 is connected with the second fixed contact 22 thereof. And the tap N +1 of the second winding is continuously switched on, 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 first change-over switch T1.
As shown in fig. 10, the first main contact MC1 is kept open, the second main contact MC2 is turned on, the first vacuum tube V1 is kept open, the second vacuum tube V2 and the third vacuum tube V3 are kept open, the movable contact of the first transfer switch T1 is connected to the first stationary contact 11 thereof, and the movable contact of the second transfer switch T2 is connected to the second stationary contact 22 thereof. The second winding tap N +1 continues to be switched on and the load current flows from the neutral outlet via 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 completely mirror-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 second change-over switch T2 is connected with the second fixed contact 22, and the moving contact of the first change-over switch T1 is connected with the first fixed contact 11. 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 connected, the first vacuum tube V1 is kept disconnected, the moving contact of the second change-over switch T2 is connected with the second fixed contact 22 thereof, and the moving contact of the first change-over switch T1 is connected with the first fixed contact 11 thereof. And the tap N +1 of the second winding is continuously switched on, 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 first change-over switch T1.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the third vacuum tube V3 is kept on, the second vacuum tube V2 is disconnected, an electric arc is generated, the first vacuum tube V1 is kept disconnected, the moving contact of the second change-over switch T2 is connected with the second fixed contact 22 thereof, and the moving contact of the first change-over switch T1 is connected with the first fixed contact 11 thereof. And 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 third vacuum tube V3, the second transition resistor R2 and the second change-over switch T2.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the third vacuum tube V3 is kept connected, the second vacuum tube V2 and the first vacuum tube V1 are kept disconnected, the moving contact of the second transfer switch T2 is connected with the second fixed contact 22 thereof, and after the second vacuum tube V2 is completely extinguished, the moving contact of the first transfer switch T1 is connected with the second fixed contact 12 thereof. And 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 third vacuum tube V3, the second transition resistor R2 and the second change-over switch T2.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the third vacuum tube V3 is kept conducted, the second vacuum tube V2 is kept disconnected, the first vacuum tube V1 is conducted, the movable contact of the second change-over switch T2 is connected with the second fixed contact 22 thereof, and the movable contact of the first change-over switch T1 is connected with the second fixed contact 12 thereof. Tap N +1 of the second windingAnd the first winding tap N are both switched on, the load current I N The neutral point lead-out end flows out from the neutral point lead-out end through a third vacuum tube V3, a second transition resistor R2, a second change-over switch T2, a first vacuum tube V1, a first transition resistor R1 and a first change-over switch T1; 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 Current I flowing through the third vacuum tube V3 V3 ＝I N /2-I C Current I flowing through the first vacuum tube V1 V1 ＝I N /2+I C (ii) a Wherein I C ＝U S V. (R1 + R2), the said U S Is an on-load tap-changer stage voltage.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the third vacuum tube V3 is disconnected, an arc is generated, the second vacuum tube V2 is kept disconnected, the first vacuum tube V1 is kept conducted, the moving contact of the second change-over switch T2 is connected with the second fixed contact 22 thereof, and the moving contact of the first change-over switch T1 is connected with the second fixed contact 12 thereof. The first winding tap N is continuously switched on, and the load current flows out from the neutral point leading-out end through the first vacuum tube V1, the first transition resistor R1 and the first change-over switch T1.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the third vacuum tube V3 and the second vacuum tube V2 are kept disconnected, the first vacuum tube V1 is kept conducted, after the third vacuum tube V3 is completely extinguished, the moving contact of the second change-over switch T2 is connected with the first fixed contact 21, and the moving contact of the first change-over switch T1 is connected with the second fixed contact 12. The first winding tap N is continuously switched on, and the load current flows out from the neutral point leading-out end through the first vacuum tube V1, the first transition resistor R1 and the first change-over switch T1.
The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the third vacuum tube V3 is kept disconnected, the second vacuum tube V2 is conducted, the first vacuum tube V1 is kept conducted, the moving contact of the second change-over switch T2 is connected with the first fixed contact 21, and the moving contact of the first change-over switch T1 is connected with the second fixed contact 12. The first winding tap N is continuously switched on, 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 second change-over switch T2.
The second main contact MC2 is kept disconnected, the first main contact MC1 is conducted, the third vacuum tube V3 is kept disconnected, the second vacuum tube V2 and the first vacuum tube V1 are kept conducted, the moving contact of the second change-over switch T2 is connected with the first fixed contact 21, and the moving contact of the first change-over switch T1 is connected with the second fixed contact 12. The first winding tap N continues to be switched on and the load current flows out of the neutral point outlet via the first main contact MC 1.
When internal switch elements in the on-load voltage regulation switch symmetrical and reciprocating transition circuit of the converter transformer are power electronic elements with controllable on-off function and double-break vacuum contacts, 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 schematically illustrated in fig. 11.
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 schematically illustrated in fig. 12.
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 on-load tap-changer inter-stage voltage; r1 and R2 are a first transition resistance and a second transition resistance.
Fig. 13 is a circuit diagram of a symmetrical reciprocating 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, as shown in fig. 13, only the single-break vacuum tube in fig. 1 is replaced with a power electronic element capable of controlling on/off, other elements are the same as those in fig. 1, the operation timing sequence is the same, and the function and function are also the same as those of the transition circuit shown in fig. 1, and are not repeated herein.
Fig. 14 is a circuit diagram of a symmetrical reciprocating 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; as shown in fig. 14, only the single-break vacuum tube in fig. 1 is replaced by a double-break vacuum tube, other elements are the same as those in fig. 1, the action timing is the same, and the function and action are also the same as those of the transition circuit shown in fig. 1, and will not be described again here.
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.
Those skilled in the art will appreciate that the invention may be practiced without these specific details.
Claims (8)
1. A symmetrical reciprocating 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), a first transition resistor (R1) and a second transition resistor (R2);
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), one end of the second vacuum tube (V2) and one end of the first transition resistor (R1) are connected with a first fixed contact (11) of the first conversion switch (T1); the other end of the third vacuum tube (V3), the other end of the second vacuum tube (V2) and one end of the second transition resistor (R2) are connected with a first fixed contact (21) of the second change-over switch; the other end of the first transition resistor (R1) is connected with a second static contact (12) of the first conversion switch (T1); the other end of the second transition resistor (R2) is connected with a second static contact (22) of the second change-over switch (T2); the other end of the first main contact (MC 1), the other end of the second main contact (MC 2), the moving contact of the first change-over switch (T1) and the moving contact of the second change-over switch (T2) are connected with a neutral point leading-out end of the on-load tap-changer.
2. The symmetrical reciprocating 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 in a conducting state, the second main contact (MC 2) and the third vacuum tube (V3) 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 first fixed contact (21), the load current flows out from the neutral point leading-out terminal through the first main contact (MC 1).
3. The symmetrical reciprocating 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 in a conducting state, the first main contact (MC 1) and the first vacuum tube (V1) 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 second fixed contact (22), a load current flows out from the neutral point leading-out terminal through the second main contact (MC 2).
4. The symmetrical reciprocating 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 symmetrical reciprocating 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 second main contact (MC 2) and the third vacuum tube (V3) are all 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 first fixed contact (21);
disconnecting the second vacuum tube (V2) after the first main contact (MC 1) is disconnected, and connecting the moving contact of the second change-over switch (T2) with the second fixed contact (22) after the second vacuum tube (V2) is completely extinguished;
after the third vacuum tube (V3) is conducted, the first winding tap (N) and the second winding tap (N + 1) are located at a bridging position, the first vacuum tube (V1) is disconnected, and after the first vacuum tube (V1) is completely extinguished, the moving contact of the first change-over switch (T1) is connected with the first fixed contact (11);
and after the second vacuum tube (V2) is conducted, the second main contact (MC 2) is conducted, the load current flows out from the neutral point through the second main contact (MC 2) from the second winding tap (N + 1), and the on-load tap changer is switched from the first winding tap (N) to the second winding tap (N + 1).
6. Voltage regulation method according to claim 5, characterized in that the current I flowing through the first vacuum tube (V1) is such that the first winding tap (N) and the second winding tap (N + 1) are in a bridging position V1 ＝I N /2+I C Current I flowing through the third vacuum tube (V3) V3 ＝I N /2-I C ；
Wherein, I N Is a load current, I C Is an interstage loop current.
7. The method for regulating voltage of claim 6 wherein an interstage ring current I C ＝U S V. (R1 + R2) in which U S For the on-load tap-changer level voltage, R1 is a first transition resistor, and R2 is a second transition resistor.
8. The symmetrical reciprocating 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 in a conducting state, the first main contact (MC 1) and the first vacuum tube (V1) 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 second fixed contact (22);
disconnecting the second vacuum tube (V2) after the second main contact (MC 2) is disconnected, and connecting the moving contact of the first change-over switch (T1) with the second fixed contact (12) after the second vacuum tube (V2) is completely extinguished;
after the first vacuum tube (V1) is conducted, the third vacuum tube (V3) is disconnected, and after the third vacuum tube (V3) is completely extinguished, the moving contact of the second change-over switch (T2) is connected with the first static contact (21);
and after the second vacuum tube (V2) is conducted, the first main contact (MC 1) is conducted, the load current flows out from the neutral point through the first main contact (MC 1) from the first winding tap (N), and the on-load tap changer is switched from the second winding tap (N + 1) to the first winding tap (N).
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| CN202211408191.6A CN115763112A (en) | 2022-11-10 | 2022-11-10 | Symmetrical reciprocating transition circuit and voltage regulating method for converter transformer on-load voltage regulating switch |
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| CN202211408191.6A CN115763112A (en) | 2022-11-10 | 2022-11-10 | Symmetrical reciprocating transition circuit and voltage regulating method for converter transformer on-load voltage regulating switch |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116721848A (en) * | 2023-06-05 | 2023-09-08 | 中国南方电网有限责任公司超高压输电公司广州局 | On-load tap changer and control method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116721848A (en) * | 2023-06-05 | 2023-09-08 | 中国南方电网有限责任公司超高压输电公司广州局 | On-load tap changer and control method thereof |
| CN116721848B (en) * | 2023-06-05 | 2024-04-02 | 中国南方电网有限责任公司超高压输电公司广州局 | On-load tap changer and control method thereof |
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