CN215680465U - Double-resistor symmetrical transition circuit of on-load tap-changer - Google Patents
Double-resistor symmetrical transition circuit of on-load tap-changer Download PDFInfo
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- CN215680465U CN215680465U CN202122374211.XU CN202122374211U CN215680465U CN 215680465 U CN215680465 U CN 215680465U CN 202122374211 U CN202122374211 U CN 202122374211U CN 215680465 U CN215680465 U CN 215680465U
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Abstract
The utility model discloses a double-resistor symmetrical transition circuit of an on-load tap-changer, which comprises: the method comprises the following steps: the switch comprises a first main contact MC1, a second main contact MC2, a first switching element, a second switching element, a third switching element, a first isolating switch Z1, a second isolating switch Z2, a change-over switch T, a first transition resistor R1 and a second transition resistor R2. Two auxiliary switch elements exist in the transition circuit, the interstage circulation current in the load switching process is switched on and off in turn, the switching program is symmetrical, the switching current tasks of the two auxiliary switch elements are consistent, the switching loss of the auxiliary switch elements is reduced, and the switching capacity of the main switch element and the auxiliary switch elements can be balanced; two transition resistors are designed in the transition circuit for alternate current limiting, so that the problems of decomposition and gas generation of transformer oil and insulation degradation caused by overhigh temperature of the transition resistors due to concentrated heating of a single transition resistor are avoided.
Description
Technical Field
The utility model relates to the technical field of on-load tap-changers, in particular to a double-resistor symmetrical transition circuit of an on-load tap-changer.
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 realize the regulation of output voltage under the condition of not interrupting load current by changing the effective turn ratio by changing a plurality of tap joints led out from a transformer winding. 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 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 carbonization and pollution of arc extinguishing in oil to the 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 operation without breaking electric arcs 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, the single resistor and the double resistor transition are adopted; single fracture, double fracture and the like are formed according to the number of the contact fractures; the various combinations can form different types of vacuum type on-load tap-changer transition circuits. The switch element in the transition circuit can be a single-break vacuum contact, a double-break vacuum contact, a power electronic element and the like; different transition circuits have different switching sequences for realizing on-load voltage regulation, and the switching tasks of the switching elements 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 on-load tap changer transition circuit has a main on-off switch element which only takes the task of switching off load current and an auxiliary switch element which only takes the task of switching off inter-stage circulating current. 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 switch element is obviously larger than the load current of the on-off of the main on-off switch element, so that the on-off tasks of the auxiliary switch element and the main on-off switch element are unbalanced.
SUMMERY OF THE UTILITY MODEL
The utility model provides a double-resistor symmetrical transition circuit of an on-load tap-changer, which has the advantages of alternate loading of auxiliary switch elements, symmetrical element distribution and symmetrical switching time sequence, and can improve the reliability and switching efficiency of the on-load tap-changer by designing two transition resistors to alternately limit current.
The purpose of the utility model is realized by the following technical scheme:
a double-resistor symmetrical transition circuit of an on-load tap-changer, comprising: a first main contact MC1, a second main contact MC2, a first switching element, a second switching element, a third switching element, a first disconnector Z1, a second disconnector Z2, a changeover switch T, a first transition resistor R1 and a second transition resistor R2;
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 switch element is connected with a change-over switch T; one end of the second switch element is respectively connected with a first winding tap N and a first main contact MC1 of a transformer regulating winding, and the other end of the second switch element is respectively connected with the first transition resistor R1 and the change-over switch T; one end of the third switching element is respectively connected with a second winding tap N +1 and a second main contact MC2 of the transformer regulating winding, and the other end of the third switching element is respectively connected with the second transition resistor R2 and the change-over switch T; one end of the first isolating switch Z1 is connected with one end of the first transition resistor R1; one end of the second isolating switch Z2 is connected with one end of a second transition resistor R2; the other ends of the first main contact MC1, the second main contact MC2, the first switching element, the first isolating switch Z1 and the second isolating switch Z2 are all connected with a neutral point outlet end of the on-load tap-changer.
As a further improvement of the present invention, the first switching element, the second switching element, and the third switching element are thyristor switches.
As a further improvement of the present invention, the first switching element, the second switching element, and the third switching element are insulated gate bipolar transistor switches.
As a further improvement of the utility model, the first, second and third switching elements are a main vacuum contact V1, a first auxiliary vacuum contact V2 and a second auxiliary vacuum contact V3, respectively.
As a further improvement of the utility model, the main vacuum contact V1, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are all single-break vacuum contacts.
As a further improvement of the present invention, the main vacuum contact V1, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are all double-break vacuum contacts.
Compared with the prior art, the utility model has the following advantages:
the utility model provides a double-resistor symmetrical transition circuit of an on-load tap-changer, wherein two auxiliary switch elements exist in the transition circuit, interstage circulation in the on-load switching process is cut off in turn, the switching procedure is symmetrical, the cut-off current tasks of the two auxiliary switch elements are consistent, the switching loss of the auxiliary switch elements is reduced, and the switching capacities of a main switch element and the auxiliary switch elements can be balanced; the transition circuit is designed with two transition resistors for alternate current limiting, so that the problems of decomposition and gas generation of transformer oil and insulation deterioration caused by overhigh temperature of the transition resistors due to concentrated heating of a single transition resistor are avoided; two isolating switches are designed, so that the isolating switch can play a role in electrical isolation, can also be used as a protection switch of an auxiliary switch element, and can prevent the fault that the current cannot be cut off after the auxiliary switch element fails.
Drawings
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes, the proportional sizes, and the like of the respective members in the drawings are merely schematic for facilitating the understanding of the present invention, and do not specifically limit the shapes, the proportional sizes, and the like of the respective members of the present invention. In the 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 an on-load tap changer transition circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 3 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 4 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 6 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 7 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 8 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 9 is a schematic diagram of an on-load tap changer transition circuit switching process according to an embodiment of the present invention;
fig. 10 is a schematic diagram of the on-off of each switch in the on-load tap changer transition circuit according to the embodiment of the present invention during the process of switching the load from winding tap N to winding tap N + 1;
fig. 11 is a schematic diagram of the on-off of each switch in the on-load tap changer transition circuit according to the embodiment of the present invention during the process of switching the load from winding tap N +1 to winding tap N;
fig. 12 is a circuit diagram of a dual-resistor symmetrical transition circuit of an on-load tap changer in which the switching elements are power electronic components according to an embodiment of the present invention;
fig. 13 is a circuit diagram of a dual-resistor symmetrical transition circuit of an on-load tap changer with a switching element of a dual-break vacuum contact according to an embodiment of the present invention.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a single embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the utility model herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Fig. 1 is a circuit diagram of an on-load tap changer transition circuit according to an embodiment of the present invention. As shown in fig. 1, a first object of the present invention is to provide a dual-resistance symmetric transition circuit of an on-load tap changer, in which two auxiliary switch elements exist in the transition circuit, and alternately cut off inter-stage loop current in an on-load switching process, a switching procedure is symmetric, and the cut-off current tasks of the two auxiliary switch elements are consistent, so that the switching loss of the auxiliary switch elements is reduced, and the switching capacities of the main switch element and the auxiliary switch elements can be balanced; the transition circuit is designed with two transition resistors for alternate current limiting, so that the problems of decomposition and gas generation of transformer oil and insulation deterioration caused by overhigh temperature of the transition resistors due to concentrated heating of a single transition resistor are avoided; two isolating switches are designed, so that the isolating switch can play a role in electrical isolation, can also be used as a protection switch of an auxiliary switch element, and can prevent the fault that the current cannot be cut off after the auxiliary switch element fails.
Specifically, the on-load tap-changer double-resistor symmetrical transition circuit includes: a first main contact MC1, a second main contact MC2, a first switching element, a second switching element, a third switching element, a first disconnector Z1, a second disconnector Z2, a changeover switch T, a first transition resistor R1 and a second transition resistor R2;
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 switch element is connected with a change-over switch T; one end of the second switch element is respectively connected with a first winding tap N and a first main contact MC1 of a transformer regulating winding, and the other end of the second switch element is respectively connected with the first transition resistor R1 and the change-over switch T; one end of the third switching element is respectively connected with a second winding tap N +1 and a second main contact MC2 of the transformer regulating winding, and the other end of the third switching element is respectively connected with the second transition resistor R2 and the change-over switch T; one end of the first isolating switch Z1 is connected with one end of the first transition resistor R1; one end of the second isolating switch Z2 is connected with one end of a second transition resistor R2; the other ends of the first main contact MC1, the second main contact MC2, the first switching element, the first isolating switch Z1 and the second isolating switch Z2 are all connected with a neutral point outlet end of the on-load tap-changer.
A voltage regulation method using the double-resistor symmetrical transition circuit of the on-load tap-changer comprises the following steps:
the first main contact MC1 is in a conducting state, the second main contact MC2 is in a disconnecting state, the second switching element, the third switching element and the first switching element are in a conducting state, the first isolating switch Z1 is in a conducting state, the second isolating switch Z2 is in a disconnecting state, and the change-over switch T is connected with the first winding tap N;
opening the first main contact MC 1;
turning off the first switching element;
controlling the change-over switch T to connect the first switching element with the second winding tap N + 1;
turning on the first switching element;
turning off the second switching element;
the first isolating switch Z1 is turned off, and the second isolating switch Z2 is turned on;
turning on the second switching element;
the second main contact MC2 is conducted to make the load current INThe switching process of the on-load tap changer from the first winding tap N to the second winding tap N +1 is ended, from the neutral point via the second main contact MC2, flowing from the second winding tap N +1 through the neutral point.
A voltage regulation method using the double-resistor symmetrical transition circuit of the on-load tap-changer comprises the following steps:
the second main contact MC2 is in a conducting state, the first main contact MC1 is in a disconnected state, the second switching element, the third switching element and the first switching element are in a conducting state, the first isolating switch Z1 is in a disconnected state, the second isolating switch Z2 is in a conducting state, and the change-over switch T is connected with the second winding tap N + 1;
opening the second main contact MC 2;
turning off the first switching element;
controlling the transfer switch T to connect the first switching element to the first winding tap N;
turning on the first switching element;
switching off the third switching element;
the first isolating switch Z1 is turned on, and the second isolating switch Z2 is turned off;
turning on the third switching element;
the first main contact MC1 is conducted to make the load current INFrom the neutral point, the first winding tap N flows out via the first main contact MC1, and the switching process of the on-load tap changer from the second winding tap N +1 to the first winding tap N ends.
The present invention will be described in detail below with reference to examples and the accompanying drawings.
Example 1
According to the on-load tap-changer transition circuit of the embodiment of the utility model, the switching element is exemplified by a single-break vacuum contact and comprises a first main contact MC1, a second main contact MC2, a main vacuum contact V1, a first auxiliary vacuum contact V2, a second auxiliary vacuum contact V3, a first disconnecting switch Z1, a second disconnecting switch Z2, a transfer switch T, a first transition resistor R1 and a second transition resistor R2. 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 main vacuum contact V1 is connected with a change-over switch T; one end of the first auxiliary vacuum contact V2 is respectively connected with a first winding tap N and a first main contact MC1 of a transformer regulating winding, and the other end of the first auxiliary vacuum contact V2 is connected with the first transition resistor R1 and the change-over switch T; one end of the second auxiliary vacuum contact V3 is respectively connected with a second winding tap N +1 of a transformer regulating winding and a second main contact MC2, and the other end of the second auxiliary vacuum contact V3 is connected with the second transition resistor R2 and a change-over switch T; one ends of the first isolating switch Z1 and the second isolating switch Z2 are respectively connected with one ends of the first transition resistor R1 and the second transition resistor R2; and the other ends of the first main contact MC1, the second main contact MC2, the main vacuum contact V1, the first isolating switch Z1 and the second isolating switch Z2 are connected with a neutral point leading-out end of the on-load tap-changer.
In the reciprocating switching process of the transition circuit of the on-load tap-changer, the first auxiliary contact V2 and the second auxiliary contact V3 alternately take on the task of breaking the inter-stage circulation current, so that the working loss of a single auxiliary vacuum contact is reduced, the failure rate of the auxiliary vacuum contact is reduced, and the reliability of the on-load tap-changer is improved.
When the first main contact MC1, the first auxiliary vacuum contact V2, the second auxiliary vacuum contact V3, the main vacuum contact V1 and the first isolating switch Z1 are all in a conducting state, the second main contact MC2 and the second isolating switch Z2 are in an off state, and the change-over switch T is connected with the first winding tap N, the on-load tap-changer transition circuit enables load current to flow out of a neutral point leading-out end through the first main contact MC 1.
When the second main contact MC2, the first auxiliary vacuum contact V2, the second auxiliary vacuum contact V3, the main vacuum contact V1 and the second isolating switch Z2 are all in a conducting state, the first main contact MC1 and the first isolating switch Z1 are in a disconnecting state, and the change-over switch T is connected with the second winding tap N +1, the on-load tap-changer transition circuit can enable the load current to flow out of the neutral point leading-out end through the second main contact MC 2.
Alternatively, the internal switch element in the on-load tap-changer double-resistance symmetrical transition circuit can be replaced by a power electronic element (comprising a thyristor switch or an insulated gate bipolar transistor switch) with controllable switching function and a double-break vacuum contact from a single-break vacuum contact.
A voltage regulation method of a double-resistor symmetrical transition circuit of an on-load tap-changer takes a single-fracture vacuum contact as an example for explanation; when the on-load tap changer is switched from the winding tap N to the winding tap N +1, the voltage regulating method comprises the following steps:
as shown in fig. 1, the first main contact MC1 is turned on, the second main contact MC2 is turned off, the main vacuum contact V1 is turned on, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are turned on, the movable contact of the transfer switch T is connected to the first stationary contact 11, the first disconnecting switch Z1 is turned on, and the second disconnecting switch Z2 is turned off. The winding tap N is switched on and the load current flows from the neutral outlet through the first main contact MC 1.
As shown in fig. 2, the first main contact MC1 is turned off, the second main contact MC2 is turned off, the main vacuum contact V1 is turned on, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are turned on, the movable contact of the transfer switch T is connected to the first stationary contact 11, the first disconnecting switch Z1 is turned on, and the second disconnecting switch Z2 is turned off. The winding tap N continues to be switched on and the load current flows from the neutral outlet through the transfer switch T, the first auxiliary vacuum contact V2, and the main vacuum contact V1.
As shown in fig. 3, the first main contact MC1 remains open, the second main contact MC2 remains open, the main vacuum contact V1 is opened, an arc is generated, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 remain conductive, the movable contact of the transfer switch T remains connected to the first stationary contact 11, the first disconnector Z1 remains conductive, and the second disconnector Z2 remains open. The winding tap N continues to be switched on and the load current flows from the neutral point outlet through the first auxiliary vacuum contact V2, the first disconnector Z1 and the first transition resistor R1.
As shown in fig. 4, the first main contact MC1 is kept open, the second main contact MC2 is kept open, the main vacuum contact V1 is kept open, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are kept conductive, and when the main vacuum contact V1 is completely extinguished, the movable contact of the change-over switch T is rotated to be connected with the second stationary contact 12, the first disconnecting switch Z1 is kept conductive, and the second disconnecting switch Z2 is kept open. The winding tap N continues to be switched on and the load current continues to flow from the neutral outlet through the first auxiliary vacuum contact V2, the first disconnector Z1, the first transition resistor R1.
As shown in fig. 5, the first main contact MC1 remains open, the second main contact MC2 remains open, the main vacuum contact V1 is turned on, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 remain on, the movable contact of the transfer switch T remains connected to the second stationary contact 12, the first disconnecting switch Z1 remains on, and the second disconnecting switch Z2 remains open. The winding tap N and the winding tap N +1 are both switched on, and the load current INFlows out of the neutral point outlet through the second auxiliary vacuum contact V3, the change-over switch T and the main vacuum contact V1; the transition circuit forms a bridge connection to generate an inter-stage circulating current IC(ii) a The current flowing through the first auxiliary vacuum contact V2 is inter-stage circulating current ICCurrent I flowing through the main vacuum contact V1V＝IN-IC(ii) a Wherein IC＝USR, said USIs an on-load tap-changer stage voltage.
As shown in fig. 6, the first main contact MC1 remains open, the second main contact MC2 remains open, the main vacuum contact V1 remains conductive, disconnecting the first auxiliary vacuum contact V2, keeping the second auxiliary vacuum contact V3 conductive, keeping the movable contact of the transfer switch T connected to the second stationary contact 12, keeping the first disconnector Z1 conductive, and keeping the second disconnector Z2 open. The winding tap N +1 is switched on and the load current flows from the neutral outlet through the second auxiliary vacuum contact V3, the transfer switch T, the main vacuum contact V1.
As shown in fig. 7, the first main contact MC1 remains open, the second main contact MC2 remains open, the main vacuum contact V1 remains conductive, the first auxiliary vacuum contact V2 remains open, the second auxiliary vacuum contact V3 remains conductive, the movable contact of the transfer switch T remains connected to the second stationary contact 12, and when the arc is completely extinguished in the first auxiliary vacuum contact V2, the first disconnecting switch Z1 is opened, and the second disconnecting switch Z2 is turned on. The winding tap N +1 is switched on and the load current flows from the neutral outlet through the second auxiliary vacuum contact V3, the transfer switch T, the main vacuum contact V1.
As shown in fig. 8, the first main contact MC1 remains open, the second main contact MC2 remains open, the main vacuum contact V1 remains conductive, turning on the first auxiliary vacuum contact V2, turning on the second auxiliary vacuum contact V3, the movable contact of the transfer switch T remains connected to the second stationary contact 12, the first disconnector Z1 remains open, and the second disconnector Z2 remains conductive. The winding tap N +1 is switched on and the load current flows from the neutral outlet through the second auxiliary vacuum contact V3, the transfer switch T, the main vacuum contact V1.
As shown in fig. 9, the first main contact MC1 is kept open, the second main contact MC2 is conducted, the main vacuum contact V1 is kept open, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are kept open, the movable contact of the transfer switch T is kept connected to the second stationary contact 12, the first disconnecting switch Z1 is kept open, and the second disconnecting switch Z2 is kept open. Winding tap N +1 is switched on and load current flows from the neutral outlet through the second main contact MC 2.
When the on-load tap-changer is switched from the winding tap N +1 to the winding tap N, the switching process is symmetrical to the switching process of the on-load tap-changer from the winding tap N to the winding tap N +1, and the specific voltage regulating method comprises the following steps:
the first main contact MC1 is disconnected, the second main contact MC2 is conducted, the main vacuum contact V1 is conducted, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are conducted, the movable contact of the change-over switch T is connected with the second fixed contact 12, the first isolating switch Z1 is disconnected, and the second isolating switch Z2 is conducted. Winding tap N +1 is switched on and load current flows from the neutral outlet through the second main contact MC 2.
The first main contact MC1 is kept open, the second main contact MC2 is opened, the main vacuum contact V1 is kept on, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are kept on, the movable contact of the change-over switch T is kept connected with the second fixed contact 12, the first disconnecting switch Z1 is kept open, and the second disconnecting switch Z2 is kept on. The winding tap N +1 continues to be switched on and the load current flows from the neutral outlet through the second auxiliary vacuum contact V3, the transfer switch T, and the main vacuum contact V1.
The first main contact MC1 keeps open, the second main contact MC2 keeps open, the main vacuum contact V1 is open, an arc is generated, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 keep on, the moving contact of the change-over switch T keeps connected with the second fixed contact 12, the first disconnecting switch Z1 keeps open, and the second disconnecting switch Z2 keeps on. The winding tap N +1 continues to be switched on, and the load current flows out from the neutral point outlet through the second auxiliary vacuum contact V3, the second disconnecting switch Z2 and the second transition resistor R2.
The first main contact MC1 keeps open, the second main contact MC2 keeps open, the main vacuum contact V1 keeps open, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 keep on, when the main vacuum contact V1 is completely extinguished, the movable contact of the change-over switch T is rotated to be connected with the first fixed contact 11, the first isolating switch Z1 keeps open, and the second isolating switch Z2 keeps on. The winding tap N +1 continues to be switched on and the load current continues to flow from the neutral outlet through the second auxiliary vacuum contact V3, the second disconnector Z2 and the second transition resistor R2.
The first main contact MC1 is kept open, the second main contact MC2 is kept open, the main vacuum contact V1 is conducted, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are kept conductive, the movable contact of the change-over switch T is kept connected with the first fixed contact 11, the first disconnecting switch Z1 is kept open, and the second disconnecting switch Z2 is kept conductive. The winding tap N and the winding tap N +1 are both switched on, and the load current INFlows out of the neutral point outlet through the first auxiliary vacuum contact V2, the change-over switch T and the main vacuum contact V1; the transition current forms a bridge connection to generate an inter-stage circulating current IC(ii) a The current flowing through the second auxiliary vacuum contact V3 is inter-stage circulating current ICCurrent I flowing through the main vacuum contact V1V＝IN+IC(ii) a Wherein IC＝USR, said USIs an on-load tap-changer stage voltage.
The first main contact MC1 remains open, the second main contact MC2 remains open, the main vacuum contact V1 remains conductive, disconnecting the second auxiliary vacuum contact V3, the first auxiliary vacuum contact V2 remains conductive, the movable contact of the change-over switch T remains connected to the first stationary contact 11, the first disconnector Z1 remains open, and the second disconnector Z2 remains conductive. The winding tap N is switched on and the load current flows from the neutral outlet through the first auxiliary vacuum contact V2, the transfer switch T, the main vacuum contact V1.
The first main contact MC1 keeps open, the second main contact MC2 keeps open, the main vacuum contact V1 keeps on, the first auxiliary vacuum contact V2 keeps on, the second auxiliary vacuum contact V3 keeps open, the moving contact of the change-over switch T keeps connected with the first fixed contact 11, when the arc in the second auxiliary vacuum contact V3 is completely extinguished, the first isolating switch Z1 is connected, and the second isolating switch Z2 is disconnected. The winding tap N is switched on and the load current flows from the neutral outlet through the first auxiliary vacuum contact V2, the transfer switch T, the main vacuum contact V1.
The first main contact MC1 remains open, the second main contact MC2 remains open, the main vacuum contact V1 remains conductive, the first auxiliary vacuum contact V2 remains conductive, the second auxiliary vacuum contact V3 is conductive, the movable contact of the change-over switch T remains connected to the first stationary contact 11, the first disconnector Z1 remains conductive, and the second disconnector Z2 remains open. The winding tap N is switched on and the load current flows from the neutral outlet through the first auxiliary vacuum contact V2, the transfer switch T, the main vacuum contact V1.
The first main contact MC1 is conducted, the second main contact MC2 is kept disconnected, the main vacuum contact V1 is kept conducted, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are kept conducted, the movable contact of the change-over switch T is kept connected with the first fixed contact 11, the first isolating switch Z1 is kept conducted, and the second isolating switch Z2 is kept disconnected. The winding tap N is switched on and the load current flows from the neutral outlet through the first main contact MC 1.
When the internal switch elements in the on-load tap-changer double-resistor symmetrical transition circuit 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 regulating method, and the description is omitted.
When the on-load tap changer is switched from N tap tapping of the winding to N +1 tap tapping of the winding, the transition circuit switching procedure schematic diagram is shown in fig. 10;
when the on-load tap changer is switched from N +1 tap tapping to N tap tapping, the transition circuit switching procedure schematic diagram is shown in fig. 11;
in an embodiment of the utility model, the switching tasks of the on-load tap changer transition circuit with vacuum contacts are as follows:
wherein, INIs the load current; u shapeSIs the voltage between the on-load tap-changer stages; r1 and R2 are transition resistances.
Example 2
Fig. 12 is a circuit diagram of a dual-resistor symmetrical transition circuit of an 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 contact in fig. 1 is replaced with a power electronic switching element GR1/GR2/GR3 with controllable on/off, and other elements are the same as those in fig. 1, and the operation timing is the same, and the function and function are the same as those of the transition circuit shown in fig. 1, and are not repeated.
Example 3
Fig. 13 is a circuit diagram of a dual resistance symmetrical transition circuit for an on-load tap changer with a switching element as a dual break vacuum contact according to an embodiment of the present invention; as shown in fig. 13, only the single-break vacuum contact in fig. 1 is replaced by the double-break vacuum contact, other elements are the same as those in fig. 1, the action timing sequence is the same, and the function are the same as those of the transition circuit shown in fig. 1, and are not described again.
The above description is only for the best mode 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 are included in the scope of the present invention.
Those skilled in the art will appreciate that the utility model may be practiced without these specific details.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of the subject matter that is disclosed herein is not intended to forego such subject matter, nor should the applicants be construed as having contemplated such subject matter as being part of the disclosed subject matter.
Claims (6)
1. A double-resistor symmetrical transition circuit of an on-load tap-changer is characterized by comprising: a first main contact MC1, a second main contact MC2, a first switching element, a second switching element, a third switching element, a first disconnector Z1, a second disconnector Z2, a changeover switch T, a first transition resistor R1 and a second transition resistor R2;
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 switch element is connected with a change-over switch T; one end of the second switch element is respectively connected with a first winding tap N and a first main contact MC1 of a transformer regulating winding, and the other end of the second switch element is respectively connected with the first transition resistor R1 and the change-over switch T; one end of the third switching element is respectively connected with a second winding tap N +1 and a second main contact MC2 of the transformer regulating winding, and the other end of the third switching element is respectively connected with the second transition resistor R2 and the change-over switch T; one end of the first isolating switch Z1 is connected with one end of the first transition resistor R1; one end of the second isolating switch Z2 is connected with one end of a second transition resistor R2; the other ends of the first main contact MC1, the second main contact MC2, the first switching element, the first isolating switch Z1 and the second isolating switch Z2 are all connected with a neutral point outlet end of the on-load tap-changer.
2. The on-load tap changer double-resistor symmetrical transition circuit of claim 1, wherein the first switching element, the second switching element, and the third switching element are thyristor switches.
3. The on-load tap changer double resistance symmetrical type transition circuit of claim 1,
the first switching element, the second switching element and the third switching element are insulated gate bipolar transistor switches.
4. The on-load tap changer double resistance symmetrical type transition circuit of claim 1,
the first, second and third switching elements are a main vacuum contact V1, a first auxiliary vacuum contact V2 and a second auxiliary vacuum contact V3, respectively.
5. The on-load tap changer double-resistance symmetrical type transition circuit of claim 4,
the main vacuum contact V1, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are all single-break vacuum contacts.
6. The on-load tap changer double-resistance symmetrical type transition circuit of claim 4,
the main vacuum contact V1, the first auxiliary vacuum contact V2 and the second auxiliary vacuum contact V3 are all double-break vacuum contacts.
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| CN202122374211.XU CN215680465U (en) | 2021-09-28 | 2021-09-28 | Double-resistor symmetrical transition circuit of on-load tap-changer |
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