CN115621063A - A single-resistor transition circuit and voltage regulation method for a converter transformer on-load tap changer - Google Patents

Abstract

The invention discloses a single-resistance transition circuit and a voltage regulation method for an on-load voltage regulating switch of a converter converter, including a first vacuum tube, a second vacuum tube, a third vacuum tube, a first transfer switch, a second transfer switch and a transition resistor, and the first A main contact and the first vacuum tube are connected to the first winding tap of the transformer voltage regulating winding; the second main contact and the third vacuum tube are connected to the second winding tap of the transformer voltage regulating winding; the first vacuum tube and the transition resistance are connected to the first The moving contact of the changeover switch is connected; the transition resistor and the other end of the third vacuum tube are connected with the moving contact of the second changeover switch. The invention adopts one transition resistor and three vacuum tubes. During the reciprocating switching process of the transition circuit, the second vacuum tube undertakes the task of breaking the load current, and the first vacuum tube and the third vacuum tube take turns to undertake the task of breaking the inter-stage circulation; Transition resistance, which is convenient for design and installation and ensures insulation distance; it has the advantages of less transition resistance and alternate loading of auxiliary vacuum contacts.

Description

A single-resistor transition circuit and voltage regulation method for a converter transformer on-load tap changer

technical field

The invention relates to the technical field of on-load tap changers, in particular to a single-resistance transition circuit and a voltage regulation method for an on-load tap changer of a converter transformer.

Background technique

The on-load tap-changer is a key component inside the power transformer. It can operate and change the effective turns ratio of several taps connected to the transformer winding under the excitation or load state of the transformer, so as to adjust the output without interrupting the load current. Voltage. On-load tap-changers are widely used, especially in converter transformers of UHV DC transmission projects, to ensure the rated firing angle of the converter during normal operation. Most of the on-load tap-changers equipped with early power transformers used the principle of high-speed resistance switching, and the load switching was performed by copper-tungsten arc contacts. This type of oil-immersed non-vacuum on-load tap-changer switches frequently, the arc contact burns relatively seriously, and the carbonization and pollution of the oil are faster, so the daily maintenance and regular inspection workload is increased for the power supply department. Vacuum-type on-load tap-changers mainly use vacuum tubes to realize arc extinguishing, which avoids carbonization and pollution of oil caused by arc extinguishing in oil; due to the short arcing time of vacuum tube breaking, low arc voltage, low arc energy consumption and contact metal gas The recondensation of the compound and the burning and corrosion of the contacts can be reduced to a minimum. The power electronic on-load tap-changer replaces the vacuum tube with power electronic components to realize arc-free operation during on-load switching.

The on-load tap-changer consists of diverter switch, tap selector and motor-drive mechanism. Among them, the diverter switch has an independent oil chamber, which is a key component for the on-load switching of the tap changer, and its core is the use of a transition circuit. Vacuum on-load tap-changers can be divided into single-contact circuits, double-contact circuits, three-contact circuits and four-contact circuits according to the number of vacuum tubes; single-resistance and double-resistance circuits according to the number of transition resistances. There are two kinds of transitions; according to the number of contact fractures, there are single fractures, double fractures, etc.; the above combinations can form a variety of vacuum on-load tap-changer transition circuits. The vacuum tubes in the transition circuit can be single-break vacuum contacts, double-break vacuum contacts, power electronic components, etc.; different transition circuits have different switching timings for on-load switching and voltage regulation, and the switching tasks of each vacuum tube will also vary. different. The topology of the transition circuit has a significant impact on the reliability of the switching process of the on-load tap-changer, as well as the failure rate and electrical life of the switch.

In the on-load tap-changer transition circuit, there are main on-off vacuum tubes that only undertake the task of breaking the load current and auxiliary vacuum tubes that only undertake the task of breaking the inter-stage circulation. In the actual UHV DC transmission project, the load current flowing through the on-load tap changer of the converter transformer is about 500-600A, and the inter-stage circulating current flowing through the transition resistor during the switching process is about 900-1000A. The off-off circulating current is obviously greater than the load current of the main on-off vacuum tube, which leads to the imbalance of the off-off tasks of the auxiliary vacuum tube and the main on-off vacuum tube. On-load tap-changers often use oil-immersed mechanical contact transfer switches, which operate during the switching process. Once there is a timing error, it will inevitably cause the transfer switch to extinguish the arc in the oil. The serious pollution of transformer oil, the accumulation of carbon production, and the reduction of insulation performance lead to the inability to extinguish the arc in the oil, which poses a greater safety risk.

Contents of the invention

In order to overcome the problems in the prior art, the object of the present invention is to propose a single-resistance transition circuit and a voltage regulation method for a converter transformer on-load tap changer, using a transition resistor, three vacuum tubes, and two transfer switches It operates after the switching process, and the components are distributed symmetrically, which can improve the reliability and switching efficiency of the on-load tap changer.

The purpose of the present invention is achieved through the following technical solutions:

A single-resistance transition circuit for a converter transformer on-load tap changer, comprising a first main contact, a second main contact, a first vacuum tube, a second vacuum tube, a third vacuum tube, a first transfer switch, a second transfer switch and transition resistance;

Wherein, one end of the first main contact and one end of the first vacuum tube are connected to the first winding tap of the voltage regulating winding of the transformer; one end of the second main contact and one end of the third vacuum tube are connected to the second tap of the voltage regulating winding of the transformer. Winding tap connections;

The other end of the first vacuum tube and one end of the transition resistor are connected to the moving contact of the first switch; the other end of the transition resistor and the other end of the third vacuum tube are connected to the moving contact of the second switch;

The second static contact of the first transfer switch and the first static contact of the second transfer switch are connected to one end of the second vacuum tube; the first static contact of the first transfer switch and the first static contact of the second transfer switch The two static contacts are connected with the neutral point lead-out end of the on-load tap-changer; end connection.

Further, when the first main contact, the first vacuum tube, and the second vacuum tube are all in the conducting state, and the third vacuum tube and the second main contact are in the disconnecting state, the first transfer switch moving contact and the second static contact When the second transfer switch moving contact is connected with the second static contact, the on-load tap changer transition circuit can make the load current flow out from the neutral point lead-out terminal through the first main contact.

Further, when the second main contact, the second vacuum tube, and the third vacuum tube are all in the conduction state, the first vacuum tube and the first main contact are in the disconnected state, the first transfer switch movable contact and the first static contact When the second transfer switch moving contact is connected to the first static contact, the on-load tap changer transition circuit can make the load current flow out from the neutral point lead-out terminal through the second main contact.

Further, 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 components with controllable on-off functions.

A method for regulating voltage based on the single-resistor transition circuit of a converter transformer on-load tap changer as described above, comprising the following steps:

The first main contact, the first vacuum tube, and the second vacuum tube are all in the conducting state, the third vacuum tube and the second main contact are in the disconnecting state, the first transfer switch moving contact is connected with the second static contact, and the second The transfer switch moving contact is connected with the second static contact;

After disconnecting the first main contact, disconnect the second vacuum tube; after the second vacuum tube is completely extinguished, turn on the third vacuum tube, and at this time the first winding tap and the second winding tap are in the bridging position; the first The vacuum tube is disconnected; after the first vacuum tube is completely extinguished, the second main contact is turned on, and the load current flows out from the second winding tap through the second main contact and from the neutral point;

After disconnecting the third vacuum tube, move the moving contact of the first transfer switch to the first static contact; move the moving contact of the second transfer switch to the first static contact; connect the second vacuum tube and the third vacuum tube, The on-load tap-changer switches from the first winding tap to the second winding tap.

Further, when the first winding tap and the second winding tap are in the bridging position, the current flowing through the third vacuum tube is calculated by the following formula:

I _V ＝ I _N -I _C

_Wherein , IV is the current flowing through the third vacuum tube, I _C is the current flowing through the first vacuum tube, which is the interstage circulation, and _IN is the load current.

Further, the current flowing through the first vacuum tube is calculated as the interstage circulation by the following formula:

I _C =U _S /R

Among them, U _S is the interstage voltage of the on-load tap changer, and R is the transition resistance.

A method for regulating voltage based on the single-resistor transition circuit of a converter transformer on-load tap changer as described above, comprising the following steps:

The second main contact, the second vacuum tube, and the third vacuum tube are all in the conduction state, the first vacuum tube and the first main contact are in the disconnected state, the first transfer switch moving contact is connected with the first static contact, and the second The transfer switch moving contact is connected with the first static contact

After the second main contact is disconnected, the second vacuum tube is disconnected; after the second vacuum tube is completely extinguished, the first vacuum tube is turned on. At this time, the first winding tap and the second winding tap are in the bridging position, and the third The vacuum tube is disconnected; after the third vacuum tube is completely extinguished, the first main contact is turned on, and the load current flows from the first winding tap through the first main contact to the neutral point;

After disconnecting the first vacuum tube, move the moving contact of the first transfer switch to the second static contact; move the moving contact of the second transfer switch to the second static contact; connect 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 bridging position, the current flowing through the first vacuum tube is calculated by the following formula:

I _V = I _N +I _C

Wherein, I _C is the current flowing through the third vacuum tube, which is the interstage circulation, and _IN is the load current.

Further, the current flowing through the third vacuum tube is calculated as the interstage circulation by the following formula:

I _C =U _S /R

Among them, U _S is the interstage voltage of the on-load tap changer, and R is the transition resistance.

Compared with the prior art, the present invention has the beneficial effects:

The transition circuit of the present invention adopts a transition resistor and three vacuum tubes. During the reciprocating switching process of the on-load tap changer, the second vacuum tube undertakes the task of breaking the load current, and the first vacuum tube and the third vacuum tube take turns to break the inter-stage The task of circulating current reduces the switching loss of the circulating vacuum tube between stages, balances the switching capacity of each vacuum tube, and improves the reliability and service life of the on-load tap changer; the use of a single transition resistor is convenient for design and installation and ensures insulation distance ; It has the advantages of less transition resistance, alternate bearing of auxiliary vacuum contacts, and high safety.

The voltage regulating method of the present invention enables the load current to switch from one side of the main contact to the other side of the main contact, and the two transfer switches do not need to operate, and the load current is converted after the switching process between the winding taps is completed. action, which avoids the situation that the arc is broken by the transfer switch during the switching process, reduces the deterioration of the insulating oil in the long-term service period of the on-load tap-changer, and is conducive to realizing the maintenance-free requirement of the service period of the on-load tap-changer; Simultaneous action of two transfer switches can effectively reduce the mechanical complexity of the on-load tap-changer and improve the reliability of the on-load tap-changer.

Description of drawings

A more complete understanding of exemplary embodiments of the present invention can be had by referring to the following drawings:

FIG. 1 is a circuit diagram of a single-resistance transition circuit of a converter transformer on-load tap switch according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of the switching process in which the first main contact is disconnected in the single-resistance transition circuit of the on-load tap changer of the converter transformer according to the embodiment of the present invention;

Fig. 3 is a schematic diagram of the switching process in which the second vacuum tube is disconnected in the single-resistance transition circuit of the on-load tap changer of the converter transformer according to the embodiment of the present invention;

4 is a schematic diagram of the switching process of the third vacuum tube conduction in the single-resistance transition circuit of the on-load tap changer of the converter transformer according to the embodiment of the present invention;

5 is a schematic diagram of a switching process in which the first vacuum tube is disconnected in the single-resistance transition circuit of the on-load tap changer of the converter transformer according to the embodiment of the present invention;

6 is a schematic diagram of the switching process of the second main contact being turned on in the single-resistance transition circuit of the on-load tap changer of the converter transformer according to the embodiment of the present invention;

Fig. 7 is a schematic diagram of the switching process of the disconnection of the third vacuum tube in the single-resistance transition circuit of the on-load tap changer of the converter transformer according to the embodiment of the present invention;

8 is a schematic diagram of the switching process of the first transfer switch and the second transfer switch in the single-resistance transition circuit of the on-load tap changer of the converter converter according to the embodiment of the present invention;

9 is a schematic diagram of the switching process of the conduction of the second vacuum tube and the third vacuum tube in the single-resistance transition circuit of the on-load tap changer of the converter transformer according to the embodiment of the present invention;

Fig. 10 is a schematic diagram of on-off of each switch in the single-resistance transition circuit of the on-load tap changer of the converter converter according to the embodiment of the present invention during the process of switching the load from the first winding tap N to the second winding tap N+1;

Fig. 11 is a schematic diagram of on-off of each switch in the single-resistance transition circuit of the on-load tap changer of the converter converter according to the embodiment of the present invention during the process of switching the load from the second winding tap N+1 to the first winding tap N;

Fig. 12 is a circuit diagram of a single-resistor transition circuit of an on-load tap changer of a converter transformer in which the switching element is a power electronic element according to an embodiment of the present invention;

Fig. 13 is a circuit diagram of a single-resistor transition circuit for an on-load tap changer of a converter transformer 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 below in conjunction with the accompanying drawings.

As shown in Fig. 1, the present invention provides a single-resistance transition circuit and a voltage regulation method for an on-load tap-changer of a converter transformer. One transition resistor and three vacuum tubes are used for reciprocating switching of the on-load tap-changer transition circuit. During the process, the second vacuum tube V2 undertakes the task of breaking the load current, and the first vacuum tube V1 and the third vacuum tube V3 take turns to undertake the task of breaking the inter-stage circulation, which reduces the switching loss of the inter-stage circulation vacuum tubes and balances the vacuum tubes. The switching capacity improves the reliability and service life of the on-load tap-changer; two transfer switches are used, and when the load current is switched from the main contact on one side to the main contact on the other side, the two The transfer switch does not need to operate, and the transfer action is performed after the load current switching process is over, which avoids the situation that the transfer switch breaks the arc during the switching process, and reduces the possibility of failure of the on-load tap changer; the use of a single transition resistor is convenient Designed to install and ensure insulation distance; it has the advantages of less transition resistance and alternate load bearing of auxiliary vacuum contacts.

The single-resistance transition circuit of the converter converter on-load tap changer of the present invention includes the first main contact MC1, the second main contact MC2, the first vacuum tube V1, the second vacuum tube V2, the third vacuum tube V3, and the first transfer switch T1, the second transfer switch T2 and the transition resistor R; wherein, one end of the first main contact MC1 is connected to the first winding tap N of the voltage regulating winding of the transformer; one end of the second main contact MC2 is connected to the voltage regulating winding of the transformer The second winding tap N+1 is connected; one end of the first vacuum tube V1 is connected to the first winding tap N of the voltage regulating winding of the transformer, and the other end is connected to one end of the transition resistor R and the moving contact of the first transfer switch T1 One end of the transition resistor R is connected to one end of the first vacuum tube V1 and the moving contact of the first changeover switch T1, and the other end is connected to one end of the third vacuum tube V3 and the moving contact of the second changeover switch T2; One end of the third vacuum tube V3 is connected to the second winding tap N+1 of the voltage regulating winding of the transformer, and the other end is connected to one end of the transition resistor R and the moving contact of the second transfer switch T2; one end of the second vacuum tube V2 is connected to The second static contact 12 of the first transfer switch T1 is connected to the first static contact 21 of the second transfer switch; the first static contact 11 of the first transfer switch T1, the second static contact of the second transfer switch T2 The contacts 22 are all connected to the neutral point terminal 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 to the neutral Sex point lead-out connection.

When the first main contact MC1, the first vacuum tube V1, and the second vacuum tube V2 are all in the on state, and the third vacuum tube V3 and the second main contact MC2 are in the off state, the moving contact of the first transfer switch T1 and its second When the static contact 12 is connected, and the second transfer switch T2 moving contact is connected to its second static contact 22, the transition circuit of the on-load tap changer can make the load current flow out from the neutral point lead-out end through the first main contact MC1 .

When the second main contact MC2, the second vacuum tube V2, and the third vacuum tube V3 are all in the on state, the first vacuum tube V1 and the first main contact MC1 are in the off state, and the moving contact of the first transfer switch T1 and its first When the static contact 11 is connected, and the second transfer switch T2 moving contact is connected to its first static contact 21, the transition circuit of the on-load tap changer can make the load current flow out from the neutral point lead-out end through the second main contact MC2 .

The internal switching elements in the single-resistance transition circuit of the on-load tap changer of the converter, that is, the first vacuum tube V1, the second vacuum tube V2 and the third vacuum tube V3, can be replaced by single-break vacuum tubes with electric power with a controllable on-off function. Electronic components and double-break vacuum tubes.

A voltage regulation method for a single-resistance transition circuit of a converter-on-load tap-changer, which is illustrated by taking a single-break vacuum tube as an example; when the on-load tap-changer is switched from the first winding tap N to the second winding tap N+1, the regulation The pressing method is as follows:

As shown in Figure 1, the first main contact MC1 is in the on state, the second main contact MC2 is in the off state, the first vacuum tube V1 and the second vacuum tube V2 are in the on state, and the third vacuum tube V3 is in the off state , the moving contact of the first transfer switch T1 is connected to its second static contact 12 , and the moving contact of the second transfer switch T2 is connected to its second static contact 22 . The first winding tap N is switched on, and the load current flows out from the neutral point lead-out end through the first main contact MC1 .

As shown in Figure 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, and the first switching The moving contact of the switch T1 is connected to its second static contact 12, the moving contact of the second transfer switch T2 is connected to its second static contact 22, the first winding tap N continues to be connected, and the load current passes through the first vacuum tube V1, the second The second vacuum tube V2 and the first transfer switch T1 flow out from the neutral point lead-out end.

As shown in Figure 3, the first main contact MC1 remains open, the second main contact MC2 remains open, the second vacuum tube V2 is disconnected, an arc is generated, the first vacuum tube V1 remains on, and the first transfer switch T1 The moving contact is connected to its second static contact 12, the moving contact of the second transfer switch T2 is connected to its second static contact 22, the first winding tap N continues to be connected, and the load current passes through the first vacuum tube V1, the transition resistor R , The second transfer switch T2 flows out from the neutral point lead-out end.

As shown in Figure 4, the first main contact MC1 remains open, the second main contact MC2 remains open, the second vacuum tube V2 remains open, and after the second vacuum tube V2 is completely extinguished, the third vacuum tube V3 is closed , the moving contact of the first transfer switch T1 is connected to its second static contact 12, the moving contact of the second transfer switch T2 is connected to its second static contact 22, the first winding tap N and the second winding tap N+1 are both connected connected, the load current I _N flows out from the neutral point terminal through the third vacuum tube V3 and the second transfer switch T2; the transition circuit forms a bridge connection, that is, the first winding tap N and the second winding tap N+1 are in the bridge connection position, generating stage Intercirculation I _C ; the current flowing through the first vacuum tube V1 is the interstage circulation I _C , the current I _{V3 flowing through the third vacuum tube V3} = I _N -I _C ; where _IC = U _S /R, the U _S is the interstage voltage of the on-load tap-changer.

As shown in Figure 5, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept disconnected, the first vacuum tube V1 is disconnected, an arc is generated, the second vacuum tube V2 is kept disconnected, and the third vacuum tube V3 is kept disconnected. is turned on, the moving contact of the first transfer switch T1 is connected to its second static contact 12, the moving contact of the second transfer switch T2 is connected to its second static contact 22, the second winding tap N+1 is connected, and the load current Through the third vacuum tube V3, the second transfer switch T2 flows out from the neutral point lead-out end.

As shown in Figure 6, the first main contact MC1 is kept open, and 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, and the third The vacuum tube V3 keeps conducting, the moving contact of the first transfer switch T1 is connected to its second static contact 12, the moving contact of the second transfer switch T2 is connected to its second static contact 22, and the second winding tap N+1 is turned on , the load current flows out from the neutral point terminal through the second main contact MC2.

As shown in Figure 7, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept on, the first vacuum tube V1 and the second vacuum tube V2 are kept disconnected, the third vacuum tube V3 is disconnected, and the first switching The moving contact of the switch T1 is connected to its second static contact 12, the moving contact of the second transfer switch T2 is connected to its second static contact 22, the second winding tap N+1 continues to be connected, and the load current passes through the second main contact The head MC2 flows out from the neutral point lead-out end.

As shown in Figure 8, the first main contact MC1 is kept disconnected, the second main contact MC2 is kept turned on, the first vacuum tube V1, the second vacuum tube V2, and the third vacuum tube V3 are kept disconnected, and the first transfer switch T1 The moving contact is connected to its first static contact 11, and the moving contact of the second transfer switch T2 is connected to its first static contact 21. The second winding tap N+1 continues to be connected, and the load current passes through the second main contact MC2 flows out from the neutral point lead-out end.

As shown in Figure 9, the first main contact MC1 is kept disconnected, 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 turned on, and the first switching The moving contact of the switch T1 is connected to its first static contact 11, the moving contact of the second transfer switch T2 is connected to its first static contact 21, the second winding tap N+1 is continuously connected, and the load current passes through the second main contact The head MC2 flows out from the neutral point lead-out end.

When the on-load tap-changer switches from the second winding tap N+1 to the first winding tap N, the switching process is symmetrical to that of the on-load tap-changer switching from the first winding tap N to the second winding tap N+1 , the pressure adjustment method is as follows:

The second main contact MC2 is in the on state, the first main contact MC1 is in the off state, the third vacuum tube V3 and the second vacuum tube V2 are in the on state, the first vacuum tube V1 is in the off state, and the first transfer switch T1 The moving contact is connected to its first static contact 11 , and the moving contact of the second transfer switch T2 is connected to its first static contact 21 . The second winding tap N+1 is switched on, and the load current flows out from the neutral point lead-out terminal through the second main contact MC2.

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 conducting, the first vacuum tube V1 is kept disconnected, and the moving contact of the first transfer switch T1 and The first static contact 11 is connected, the moving contact of the second transfer switch T2 is connected to its first static contact 21, the second winding tap N+1 is continuously connected, and the load current passes through the third vacuum tube V3, the second vacuum tube V2, The second transfer switch T2 flows out from the neutral point lead-out end.

The second main contact MC2 is kept disconnected, the first main contact MC1 is kept disconnected, the second vacuum tube V2 is disconnected, an arc is generated, the third vacuum tube V3 is kept conducting, and the moving contact of the first changeover switch T1 and its first The static contact 11 is connected, the moving contact of the second transfer switch T2 is connected with its first static contact 21, the second winding tap N+1 continues to be connected, and the load current passes through the third vacuum tube V3, the second transfer switch T2, the transition Resistor R flows out from the neutral point.

The second main contact MC2 remains open, the first main contact MC1 remains open, and the second vacuum tube V2 remains open. After the second vacuum tube V2 is completely extinguished, the first vacuum tube V1 is closed, and the first transfer switch T1 The moving contact is connected to its first static contact 11, the moving contact of the second transfer switch T2 is connected to its first static contact 21, the first winding tap N and the second winding tap N+1 are both connected, and the load current I _N flows out from the terminal of the neutral point through the first vacuum tube V1 and the first transfer switch T1; the transition circuit forms a bridge to generate an inter-stage circulating current I _C ; the current flowing through the third vacuum tube V3 is an inter-stage circulating current I _C , which flows through the first The current I _V1 of the vacuum tube V1 = I _N + I _C ; where I _C = U _S /R, and the U _S is the interstage voltage of the on-load tap changer.

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 on, and the first switching The moving contact of the switch T1 is connected to its first static contact 11, the moving contact of the second transfer switch T2 is connected to its first static contact 21, the first winding tap N is connected, and the load current passes through the first vacuum tube V1, the first Transfer switch T1 flows out from the neutral point lead-out end.

The second main contact MC2 is kept disconnected, and 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 are kept disconnected, and the first vacuum tube V1 is kept conducting. The moving contact of the first transfer switch T1 is connected to its first static contact 11, the moving contact of the second transfer switch T2 is connected to its first static contact 21, the first winding tap N is connected, and the load current passes through the first main contact The head MC1 flows out from the neutral point lead-out end.

The second main contact MC2 is kept disconnected, the first main contact MC1 is kept turned on, the third vacuum tube V3 and the second vacuum tube V2 are kept disconnected, the first vacuum tube V1 is disconnected, and the moving contact of the first transfer switch T1 and its The first static contact 11 is connected, the moving contact of the second transfer switch T2 is connected to its first static contact 21, the first winding tap N continues to be connected, and the load current flows out from the neutral point terminal through the first main contact MC1 .

The second main contact MC2 is kept disconnected, the first main contact MC1 is kept on, the third vacuum tube V3, the second vacuum tube V2, and the first vacuum tube V1 are kept disconnected, and the moving contact of the first transfer switch T1 is connected to the second vacuum tube. The static contact 12 is connected, and the second transfer switch T2 moving contact is connected with its second static contact 22, the first winding tap N is continuously connected, and the load current flows out from the neutral point terminal through the first main contact MC1.

The second main contact MC2 is kept disconnected, the first main contact MC1 is kept on, the third vacuum tube V3 is kept off, the second vacuum tube V2 and the first vacuum tube V1 are turned on, and the moving contact of the first transfer switch T1 and The second static contact 12 is connected, the moving contact of the second transfer switch T2 is connected to its second static contact 22, the first winding tap N continues to be connected, and the load current flows out from the neutral point terminal through the first main contact MC1 .

When the internal switching element in the single-resistance transition circuit of the on-load tap changer of the converter converter is a power electronic element with a controllable on-off function and a double-break vacuum tube, the action sequence of the switching element is consistent with the voltage regulation method, and will not be repeated. .

When the on-load tap changer is switched from N-tap tap of the first winding to N+1 tap of the second winding, the conversion process of the transition circuit is shown in Fig. 10 .

When the on-load tap changer is switched from the N+1 tap of the second winding to the N tap of the first winding, the conversion process of the transition circuit is shown in Figure 11.

In the embodiment of the present invention, the switching tasks of the on-load tap-changer transition circuit using vacuum tubes are shown in the following table:

Among them, _{IN is the load current; U S is} the interstage voltage of the on-load tap changer; R is the transition resistance.

Fig. 12 is a circuit diagram of a single-resistor transition circuit of a converter converter on-load tap changer switch in which the switching element is a power electronic component according to an embodiment of the present invention. As shown in Fig. 12, only the single-break vacuum tube in Fig. 1 is replaced with a The other components of the power electronic components that control the on-off function are the same as those in Figure 1, and the action sequence is consistent, and the functions and functions of the transition circuit shown in Figure 1 are also the same, and will not be repeated here.

Fig. 13 is a circuit diagram of a single-resistor transition circuit of an on-load tap changer of a converter transformer in which the switching element is 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 with a double-break The other components of the vacuum tube are the same as those in Fig. 1, and the sequence of action is the same, and the functions and effects of the transition circuit shown in Fig. 1 are also the same, and will not be repeated here.

The transition circuit of the present invention adopts a transition resistor and three vacuum tubes. During the reciprocating switching process of the transition circuit, the second vacuum tube V2 undertakes the task of breaking the load current, and the first vacuum tube V1 and the third vacuum tube V3 take turns to break the load current. The task of circulating current between stages; using a single transition resistor, it is easy to design and install and ensure the insulation distance; it has the advantages of less transition resistance and alternate load bearing of auxiliary vacuum contacts.

The above description is only the best specific implementation mode of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of changes or modifications within the technical scope disclosed in the present invention. Replacement, such as installing an isolating switch on the line where the existing vacuum tube is located, to achieve electrical isolation and protection, should be covered within the protection 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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