A double-resistance reciprocating transition circuit and voltage regulating method for on-load tap changer

Abstract

The application discloses a double-resistance reciprocating transition circuit of an on-load tap changer and a voltage regulating method. The double-resistance reciprocating transition circuit comprises a first main current flow switch, a second main current flow switch and a conversion switch. The first end of the first main current flow switch and the first end of a first transition resistor are connected with the first end of a first switch element. The first end of the second main current flow switch and the first end of a second transition resistor are connected with the first end of a second switch element. The second end of the first switch element and the second end of the second switch element are connected with the moving contact of the conversion switch. The second end of the first main current flow switch, the second end of the second main current flow switch and the second end of a third switch element are connected with the second end of a fourth switch element. The transition circuit adopts two transition resistors to limit current, can effectively limit the inter-stage short-circuit current in the switching process, and reduce the resistance heating. The mechanical on-load tap changer adopting the transition circuit and the voltage regulating method is mirror-symmetrical in the positive and negative reciprocating switching process, and does not need a mechanical track changing mechanism.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of on-load tap changer, and particularly relates to a double-resistor reciprocating transition circuit of on-load tap changer and a voltage regulating method. BACKGROUND

[0002] On-load tap changer is a key component in power transformer, which can operate in the state of transformer excitation or load, and change the effective number of turns by changing the connection of several tap terminals in transformer winding, so as to adjust the output voltage without interrupting the load current. On-load tap changer is widely used, especially in converter transformer of extra-high voltage direct current transmission project, to ensure the rated trigger angle of the converter in normal operation.

[0003] The on-load tap changer of early power transformer mostly adopts high-speed resistance switching principle, and relies on copper-tungsten arc contact to perform load conversion. This kind of oil-immersed non-vacuum on-load tap changer is switched frequently, and the corresponding arc contact burning loss is relatively serious, and the carbonization and pollution of oil are relatively fast, thus increasing the daily maintenance and regular maintenance workload of power supply department. The vacuum on-load tap changer mainly uses vacuum tube to realize arc extinguishing, avoiding the carbonization and pollution of oil in arc extinguishing. Due to the short arc interruption time, low arc voltage, small arc energy consumption and recondensation of contact metal vaporization of vacuum tube, the contact burning loss and corrosion can be minimized. The power electronic on-load tap changer replaces the vacuum tube with power electronic components to realize the non-arc interruption operation in the on-load switching process.

[0004] The on-load tap changer is composed of switching switch, tap selector and electric mechanism; wherein, the switching switch has an independent oil chamber, and is a key component for realizing on-load switching of the tap changer, and the core is to adopt a transition circuit. The vacuum on-load tap changer can be divided into single-contact circuit, double-contact circuit, triple-contact circuit and four-contact circuit according to the number of vacuum tubes; and can be divided into single-resistance and double-resistance transition according to the number of transition resistors; and can be divided into single-break and double-break according to the number of contact breaks; the above combinations can constitute different types of transition circuits of vacuum on-load tap changer. The switching elements in the transition circuit can be single-break vacuum contact, double-break vacuum contact, power electronic components and the like; different transition circuits have different switching sequences in order to realize on-load voltage regulation, and the switching tasks of each switching element are also different. The topology structure of the transition circuit has a significant influence on the reliability of the on-load tap changer switching process, and the failure rate and electrical life of the switch.

[0005] The control timing of the existing vacuum type load tap changer transition circuit is asymmetric from winding tap N to winding tap N+1 and from winding tap N+1 to winding tap N, and in the process of reciprocating movement of the switching core, the cam mechanism needs to realize lifting and track changing, thereby increasing the complexity of mechanical manufacturing and the failure rate of the switch. SUMMARY

[0006] The present application aims to provide a load tap changer double-resistance reciprocating transition circuit and voltage regulating method, which uses two transition resistors to limit current, can effectively limit the inter-stage short-circuit current in the switching process and reduce the resistance heating; the switching elements for breaking the load current and the inter-stage circulating current are configured in duplicate, and alternately bear the breaking task; the transition circuit can bear symmetric reciprocating timing, and the mechanical load tap changer using the transition circuit and the voltage regulating method has mirror-symmetric action timing in the forward and reverse reciprocating switching process, without the need for a mechanical track changing mechanism.

[0007] The present application is achieved by the following technical solutions:

[0008] A load tap changer double-resistance reciprocating transition circuit, comprising a first main current flow switch, a second main current flow switch, a first switching element, a second switching element, a third switching element, a fourth switching element, a first transition resistor, a second transition resistor and a changeover switch.

[0009] The first end of the first main current flow switch, the first end of the first transition resistor and the first end of the first switching element are connected; the first end of the second main current flow switch, the first end of the second transition resistor and the first end of the second switching element are connected; the second end of the first switching element and the second end of the second switching element are connected to the moving contact of the changeover switch; the first end of the third switching element and the second end of the first transition resistor are connected to the first stationary contact of the changeover switch; the first end of the fourth switching element and the second end of the second transition resistor are connected to the second stationary contact of the changeover switch; the second end of the first main current flow switch, the second end of the second main current flow switch and the second end of the third switching element are connected to the second end of the fourth switching element.

[0010] Further, a transformer voltage regulating winding is further included, and the first end of the first main current flow switch, the first end of the first transition resistor and the first end of the first switching element are connected to the first winding tap of the transformer voltage regulating winding; the first end of the second main current flow switch, the first end of the second transition resistor and the first end of the second switching element are connected to the second winding tap of the transformer voltage regulating winding.

[0011] Further, the load tap changer is further included, and the second end of the first main current switch, the second end of the second main current switch, the second end of the third switch element and the second end of the fourth switch element are connected with a neutral point leading end of the load tap changer.

[0012] Further, the first switch element, the second switch element, the third switch element and the fourth switch element are single-break vacuum tubes, double-break vacuum tubes or power electronic elements with controllable on-off function.

[0013] Further, the power electronic element with controllable on-off function is a thyristor or an insulated gate bipolar transistor.

[0014] Further, the first disconnector is further included, and the second end of the first switch element is connected with the moving contact of the change-over switch through the first disconnector.

[0015] Further, the second disconnector is further included, and the second end of the second switch element is connected with the moving contact of the change-over switch T through the second disconnector.

[0016] Further, when the first main current switch, the first switch element and the third switch element are in the on state, the moving contact of the change-over switch T is connected with the first static contact, and the second main current switch, the second switch element and the fourth switch element are in the off state, the load current flows out from the neutral point leading end through the first main current switch from the first winding tap.

[0017] When the second main current switch, the second switch element and the fourth switch element are in the on state, the moving contact of the change-over switch is connected with the second static contact, and the first main current switch, the first switch element and the third switch element are in the off state, the load current flows out from the neutral point leading end through the second main current switch from the second winding tap.

[0018] A voltage regulating method based on the above load tap changer double-resistance reciprocating transition circuit, comprising the following steps:

[0019] The first main current switch, the first switch element and the third switch element are in the on state, the moving contact of the change-over switch is connected with the first static contact, and the second main current switch, the second switch element and the fourth switch element are in the off state.

[0020] The first main current switch is turned off, the first switch element is turned off, the moving contact of the change-over switch is left empty, the fourth switch element is turned on, the third switch element is turned off, the moving contact of the change-over switch is connected with the second static contact, the second switch element is turned on, and the second main current switch is turned on; the load current flows out from the neutral point leading end through the second main current switch from the second winding tap, and the load tap changer is switched from the first winding tap to the second winding tap.

[0021] A voltage regulating method based on the above-mentioned double-resistance reciprocating transition circuit of the on-load tap changer, the second main current switch, the second switch element and the fourth switch element are in the conducting state; the moving contact of the conversion switch is connected with the second static contact, the first main current switch, the first switch element and the third switch element are in the open state; the second main current switch is turned off, the second switch element is turned off, the moving contact of the conversion switch is left empty, the third switch element is turned on, the fourth switch element is turned off, the moving contact of the conversion switch is connected with the first static contact, the first switch element is turned on, the first main current switch is turned on, the load current flows out from the neutral point lead-out end through the first main current switch from the second winding tap, and the on-load tap changer switches from the second winding tap to the first winding tap.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The transition circuit in the present application adopts two transition resistors for current limiting, which can effectively limit the inter-stage short-circuit current in the switching process while reducing the resistance heating; the switch elements for opening the load current and the inter-stage circulating current are configured in a dual mode, and alternately bear the opening task; the transition circuit can bear a symmetric reciprocating time sequence, and the mechanical on-load tap changer adopting the transition circuit and the voltage regulating method has a mirror-symmetric action time sequence in the forward and reverse reciprocating switching process, without the need for a mechanical track changing mechanism. In the present application, the first switch element and the second switch element take turns to bear the task of opening the load current, and the third switch element and the fourth switch element take turns to bear the task of opening the inter-stage circulating current, thereby reducing the degree of working loss of a single switch element, balancing the switching capacity between the switch elements, and reducing the failure rate of the switch elements.

[0024] Further, in the double-resistance reciprocating transition circuit of the on-load tap changer provided by the present application, a conversion switch is designed, which can not only play an electrical isolation role, but also serve as a protection switch for the switch elements to prevent the failure of the switch elements from causing the failure of opening the current. The transition circuit and the voltage regulating method have a mirror-symmetric action time sequence in the forward and reverse reciprocating switching process, avoiding the mechanical structure track changing operation; the transition circuit is designed with two transition resistors for current limiting, which not only makes the recovery voltage of the switch elements low, but also reduces the inter-stage short-circuit current in the switching process. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings needed to be used in the embodiments or prior art description; obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0026] Figure 1 Circuit diagram of a load tap changer transition circuit according to an embodiment of the application;

[0027] Figure 2 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0028] Figure 3 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0029] Figure 4 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0030] Figure 5 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0031] Figure 6 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0032] Figure 7 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0033] Figure 8 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0034] Figure 9 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0035] Figure 10 Schematic diagram of a load tap changer transition circuit switching process according to an embodiment of the application;

[0036] Figure 11 Schematic diagram of the switching of the switches in a load tap changer transition circuit according to an embodiment of the application during the switching of the load from winding tap N to winding tap N+1 ;

[0037] Figure 12 Schematic diagram of the switching of the switches in a load tap changer transition circuit according to an embodiment of the application during the switching of the load from winding tap N+1 to winding tap N;

[0038] Figure 13 Circuit diagram of a load tap changer double-resistor shuttle transition circuit according to an embodiment of the application, in which the switching elements are power electronic elements;

[0039] Figure 14Circuit diagram of the double-resistance reciprocating transition circuit of the load-tap-changer with double-break vacuum contact according to the embodiment of the present application;

[0040] Figure 15 Circuit diagram of the transition circuit according to the embodiment of the present application with an example disconnecting switch added to play the role of electrical isolation and backup protection. DETAILED DESCRIPTION

[0041] In order to make the personnel in the technical field better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the person of ordinary skill in the art without making creative labor should belong to the scope of protection of the present application.

[0042] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0043] The present application will be further described in detail below in combination with the accompanying drawings.

[0044] The double-resistance reciprocating transition circuit of the on-load tap changer comprises a first main current flow switch, a second main current flow switch, a first switch element, a second switch element, a third switch element, a fourth switch element, a first transition resistor, a second transition resistor and a changeover switch. The first end of the first main current flow switch, the first end of the first transition resistor and the first end of the first switch element are connected, and the first end of the first main current flow switch, the first end of the first transition resistor and the first end of the first switch element are connected with the first winding tap N of the transformer voltage regulating winding. The first end of the second main current flow switch, the first end of the second transition resistor and the first end of the second switch element are connected, and the first end of the second main current flow switch, the first end of the second transition resistor and the first end of the second switch element are connected with the second winding tap N+1 of the transformer voltage regulating winding. The second end of the first switch element and the second end of the second switch element are connected with the moving contact of the changeover switch. The first end of the third switch element and the second end of the first transition resistor are connected with the first stationary contact on the side of the changeover switch winding tap N. The first end of the fourth switch element and the second end of the second transition resistor are connected with the second stationary contact on the side of the changeover switch winding tap N+1. The second end of the first main current flow switch, the second end of the second main current flow switch and the second end of the third switch element are connected with the second end of the fourth switch element, and the second end of the first main current flow switch, the second end of the second main current flow switch, the second end of the third switch element and the second end of the fourth switch element are connected with the neutral point lead-out end of the on-load tap changer.

[0045] Further, the changeover switch constitutes a single-throw three-pole switch. The moving contact of the changeover switch is connected with the first stationary contact on the side of the first winding tap N, constituting the first working state of the switch. The moving contact of the changeover switch is connected with the second stationary contact on the side of the second winding tap N+1, constituting the second working state of the switch. The moving contact of the changeover switch is idle, and is not connected with the first stationary contact and the second stationary contact, constituting the third working state of the switch.

[0046] Further, the first switch element, the second switch element, the third switch element and the fourth switch element can be single-break vacuum tubes, double-break vacuum tubes or power electronic elements (such as thyristors or insulated gate bipolar transistors) with controllable on-off function.

[0047] Further, additional disconnecting switches can be added at any position in the transition circuit to play the role of electrical isolation and backup protection.

[0048] In the embodiment of the present application, the first main current flow switch and the second main current flow switch are used for long-term current carrying of the load current; the first switch element and the second switch element are used for alternately breaking the load current; the third switch element and the fourth switch element are used for alternately breaking the inter-stage circulating current. The first transition resistance and the second transition resistance are used for limiting the inter-stage circulating current when the transformer voltage regulating winding first winding tap N and second winding tap N+1 are bridged. The actual selection of the specifications of each element is determined by the actual working condition of the transition circuit.

[0049] Figure 1 The circuit diagram of the double-resistance reciprocating transition circuit of the on-load tap changer according to the embodiment of the present application is shown in FIG. 1. Figure 1 As shown in FIG. 1, the on-load tap changer double-resistance reciprocating transition circuit of the embodiment of the present application takes single-break vacuum tubes as an example of the switch elements, i.e., the first switch element is a first vacuum tube V1, the second switch element is a second vacuum tube V2, the third switch element is a third vacuum tube V3, and the fourth switch element is a fourth vacuum tube V4, which comprises: a first main current flow switch MC1, a second main current flow switch MC2, the first vacuum tube V1, the second vacuum tube V2, the third vacuum tube V3, the fourth vacuum tube V4, a first transition resistance R1, a second transition resistance R2, and a changeover switch T.

[0050] The first end of the first main current flow switch MC1 is connected to the first end of the first transition resistance R1 and the first end of the first vacuum tube V1, and is used for being connected to the first winding tap N of the transformer voltage regulating winding; the first end of the second main current flow switch MC2 is connected to the first end of the second transition resistance R2 and the first end of the second vacuum tube V2, and is used for being connected to the second winding tap N+1 of the transformer voltage regulating winding; the second end of the first vacuum tube V1 and the second end of the second vacuum tube V2 are connected to the moving contact of the changeover switch T; the first end of the third vacuum tube V3 and the second end of the first transition resistance R1 are connected to the first stationary contact 11 on the winding tap N side of the changeover switch T; the first end of the fourth vacuum tube V4 and the second end of the second transition resistance R2 are connected to the second stationary contact 12 on the winding tap N+1 side of the changeover switch T; the second end of the first main current flow switch MC1, the second end of the second main current flow switch MC2, the second end of the third vacuum tube V3, and the second end of the fourth vacuum tube V4 are connected to the neutral point lead-out end of the on-load tap changer.

[0051] In the embodiment of the present application, when the first main current flow switch MC1, the first vacuum tube V1 and the third vacuum tube V3 are all in the conducting state, the moving contact of the change-over switch T is connected with the first static contact 11 on the side of the first winding tap N, and the on-load tap changer is in the first working state; when the second main current flow switch MC2, the second vacuum tube V2 and the fourth vacuum tube V4 are all in the open state, the on-load tap changer transition circuit can make the load current flow out from the neutral point outlet end through the first main current flow switch MC1 from the first winding tap N. When the second main current flow switch MC2, the second vacuum tube V2 and the fourth vacuum tube V4 are all in the conducting state, the moving contact of the change-over switch T is connected with the second static contact 12 on the side of the second winding tap N+1, and the on-load tap changer is in the second working state; when the first main current flow switch MC1, the first vacuum tube V1 and the third vacuum tube V3 are all in the open state, the on-load tap changer transition circuit can make the load current flow out from the neutral point outlet end through the second main current flow switch MC2 from the second winding tap N+1.

[0052] In the embodiment of the present application, the transition circuit adopts two transition resistors for current limiting, which can effectively limit the inter-stage short-circuit current in the switching process and reduce the resistance heating; the switching elements for opening the load current and the inter-stage circulating current are all configured in dual mode, and alternately bear the opening task; the transition circuit can bear the symmetrical reciprocating time sequence, and the mechanical on-load tap changer adopting the transition circuit and the voltage regulating method has the mirror image symmetrical action time sequence in the forward and reverse reciprocating switching process, and does not need a mechanical track changing mechanism. Specifically, in the on-load tap changer double-resistor reciprocating transition circuit provided by the present application, a change-over switch is designed, which can play an electrical isolation role and also can be used as a protection switch of the switching element to prevent the failure of the switching element from causing the failure of opening the current. The transition circuit and the voltage regulating method have the mirror image symmetrical action time sequence in the forward and reverse reciprocating switching process, and avoid the mechanical track changing operation; the transition circuit is designed with two transition resistors for current limiting, which can reduce the inter-stage short-circuit current in the switching process while reducing the recovery voltage of the switching element.

[0053] In the embodiment of the present application, the first vacuum tube and the second vacuum tube alternately bear the task of opening the load current, and the third vacuum tube and the fourth vacuum tube alternately bear the task of opening the inter-stage circulating current, which reduces the working loss degree of a single vacuum tube, balances the switching capacity among the vacuum tubes, and reduces the failure rate of the vacuum tubes.

[0054] The voltage regulating method of the on-load tap changer double-resistor reciprocating transition circuit in the embodiment of the present application is described by taking a single-break vacuum tube as an example. When the on-load tap changer switches from the current transformer winding tap to the preselected new transformer winding tap, i.e. switches from the first winding tap N to the second winding tap N+1, the switching process is as follows:

[0055] The first main current flow switch MC1, the first vacuum tube V1 and the third vacuum tube V3 are in a conducting state; the moving contact of the change-over switch T is connected with the first stationary contact 11 on the side of the first winding tap N, and is in a first working state; the second main current flow switch MC2, the second vacuum tube V2 and the fourth vacuum tube V4 are in a disconnected state;

[0056] The first main current flow switch MC1 is disconnected;

[0057] The first vacuum tube V1 is disconnected, and an arc is generated;

[0058] After the first vacuum tube V1 is completely extinguished, the first working state that the moving contact of the change-over switch T is connected with the first stationary contact 11 is changed to a third working state that the moving contact of the change-over switch is vacant;

[0059] The fourth vacuum tube V4 is conducted;

[0060] The third vacuum tube is disconnected, and an arc is generated;

[0061] After the third vacuum tube V3 is completely extinguished, the third working state that the moving contact of the change-over switch is vacant is changed to a second working state that the moving contact of the change-over switch is connected with the second stationary contact 12;

[0062] The second vacuum tube V2 is conducted;

[0063] The second main current flow switch MC2 is conducted;

[0064] The load current flows out from the neutral point lead-out end of the second main current flow switch from the second winding tap N+1, and the switching process of the on-load tap changer from the first winding tap N to the second winding tap N+1 is ended.

[0065] The switching process of the on-load tap changer from the second winding tap N+1 to the first winding tap N of the voltage regulating method of the on-load tap changer double-resistance reciprocating transition circuit of the embodiment of the application is described by taking a single-break vacuum tube as an example, and is as follows:

[0066] The second main current flow switch MC2, the second vacuum tube V2 and the fourth vacuum tube V4 are in a conducting state; the moving contact of the change-over switch T is connected with the second stationary contact 12 on the side of the second winding tap N+1, and is in a second working state; the first main current flow switch MC1, the first vacuum tube V1 and the third vacuum tube V3 are in a disconnected state;

[0067] The second main current flow switch MC2 is disconnected;

[0068] The second vacuum tube V2 is disconnected, and an arc is generated;

[0069] After the second vacuum tube V2 is completely extinguished, the second working state of the moving contact of the change-over switch T connected with the second static contact 12 is operated to the third working state of the moving contact of the change-over switch being vacant;

[0070] The third vacuum tube V3 is turned on;

[0071] The fourth vacuum tube V4 is turned off, and an arc is generated;

[0072] After the fourth vacuum tube is completely extinguished, the third working state of the moving contact of the change-over switch T being vacant is operated to the first working state of the moving contact of the change-over switch T connected with the first static contact 12;

[0073] The first vacuum tube V1 is turned on;

[0074] The first main current flow switch MC1 is turned on;

[0075] The load current flows out from the neutral point outlet end through the first main current flow switch from the second winding tap N, and the switching process of the on-load tap changer is ended from the second winding tap N+1 to the first winding tap N.

[0076] The voltage regulating method of the on-load tap changer double-resistance reciprocating transition circuit is described by taking a single-break vacuum tube as an example; when the on-load tap changer is switched from the winding tap N to the winding tap N+1, the voltage regulating method is as follows:

[0077] As shown in Figure 2 , the first main current flow switch MC1, the first vacuum tube V1 and the third vacuum tube V3 are all in the on state; the moving contact of the change-over switch T is connected with the first static contact 11 on the first winding tap N side, and is in the first working state; the second main current flow switch MC2, the second vacuum tube V2 and the fourth vacuum tube V4 are all in the off state; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the first main current flow switch MC1.

[0078] As shown in Figure 3 , the first main current flow switch MC1 is turned off, and the first vacuum tube V1 and the third vacuum tube V3 remain in the on state; the moving contact of the change-over switch T is connected with the first static contact 11 on the first winding tap N side, and remains in the first working state; the second main current flow switch MC2, the second vacuum tube V2 and the fourth vacuum tube V4 remain in the off state; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the change-over switch T, the first vacuum tube V1 and the third vacuum tube V3.

[0079] As shown in Figure 4As shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 remains open, and the third vacuum tube V3 remains conducting; the moving contact of the changeover switch T is connected with the first static contact 11, and the first working state is maintained; the second main current flow switch MC2, the second vacuum tube V2, and the fourth vacuum tube V4 remain open; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the first transition resistance R1 and the third vacuum tube V3.

[0080] As shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 remains open, and the third vacuum tube V3 remains conducting; the moving contact of the changeover switch T is connected with the first static contact 11, and the first working state is maintained; the second main current flow switch MC2, the second vacuum tube V2, and the fourth vacuum tube V4 remain open; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the first transition resistance R1 and the third vacuum tube V3. Figure 5 As shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 remains open, and the third vacuum tube V3 remains conducting; the moving contact of the changeover switch T is connected with the first static contact 11, and the first working state is maintained; the second main current flow switch MC2, the second vacuum tube V2, and the fourth vacuum tube V4 remain open; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the first transition resistance R1 and the third vacuum tube V3.

[0081] Figure 6 As shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 remains open, and the third vacuum tube V3 remains conducting; the moving contact of the changeover switch T is connected with the first static contact 11, and the first working state is maintained; the second main current flow switch MC2, the second vacuum tube V2, and the fourth vacuum tube V4 remain open; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the first transition resistance R1 and the third vacuum tube V3. N C V3 N C V4 N C C S S

[0082] As shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 remains open, and the third vacuum tube V3 remains conducting; the moving contact of the changeover switch T is connected with the first static contact 11, and the first working state is maintained; the second main current flow switch MC2, the second vacuum tube V2, and the fourth vacuum tube V4 remain open; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the first transition resistance R1 and the third vacuum tube V3. Figure 7 As shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 remains open, and the third vacuum tube V3 remains conducting; the moving contact of the changeover switch T is connected with the first static contact 11, and the first working state is maintained; the second main current flow switch MC2, the second vacuum tube V2, and the fourth vacuum tube V4 remain open; the winding tap N is connected, and the load current flows out from the neutral point outlet end through the first transition resistance R1 and the third vacuum tube V3.​​​​​​​​​​​​

[0083] As Figure 8 shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 and the third vacuum tube V3 remain open; the moving contact of the changeover switch is connected with the second static contact 12, and remains in the second working state; the second main current flow switch MC2 remains open, the fourth vacuum tube V4 remains conducting, the second vacuum tube V2 is conducting, the winding tap N+1 is connected, and the load current flows out from the neutral point outlet end through the second vacuum tube V2 and the fourth vacuum tube V4.

[0084] As Figure 9 shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 and the third vacuum tube V3 remain open; the moving contact of the changeover switch is connected with the second static contact 12, and remains in the second working state; the second main current flow switch MC2 remains open, the fourth vacuum tube V4 remains conducting, the second vacuum tube V2 is conducting, the winding tap N+1 is connected, and the load current flows out from the neutral point outlet end through the second vacuum tube V2 and the fourth vacuum tube V4.

[0085] As Figure 10 shown, the first main current flow switch MC1 remains open, the first vacuum tube V1 and the third vacuum tube V3 remain open; the moving contact of the changeover switch is connected with the second static contact 12, and remains in the second working state; the second vacuum tube V2, the fourth vacuum tube V4 remain conducting, the second main current flow switch MC2 is conducting, the winding tap N+1 is connected, and the load current flows out from the neutral point outlet end through the second main current flow switch MC2 from the second winding tap N+1.

[0086] When the on-load tap changer switches 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 switching from the winding tap N to the winding tap N+1, and the specific voltage regulation method is as follows:

[0087] The second main current flow switch MC2, the second vacuum tube V2, and the fourth vacuum tube V4 are all in the conducting state; the moving contact of the changeover switch T is connected with the second static contact 12 on the side of the second winding tap N+1, and is in the second working state; the first main current flow switch MC1, the first vacuum tube V1, and the third vacuum tube V3 are all in the open state; the winding tap N+1 is connected, and the load current flows out from the neutral point outlet end through the second main current flow switch MC2 from the second winding tap N+1.

[0088] The second main current-carrying switch MC2 is disconnected, while the second vacuum tube V2 and the fourth vacuum tube V4 remain conducting. The moving contact of the changeover switch T is connected to the second stationary contact 12 on the N+1 side of the second winding tap, maintaining the second operating state. The first main current-carrying switch MC1, the first vacuum tube V1, and the third vacuum tube V3 remain disconnected. The winding tap N+1 is connected, and the load current flows out from the neutral point lead-out terminal through the changeover switch T, the second vacuum tube V2, and the fourth vacuum tube V4.

[0089] The second main current-carrying switch MC2 remains open, disconnecting the second vacuum tube V2 and generating an electric arc, while the fourth vacuum tube V4 remains closed. The moving contact of the changeover switch T is connected to the second stationary contact 12 on the N+1 side of the second winding tap, maintaining the second operating state. The first main current-carrying switch MC1, the first vacuum tube V1, and the third vacuum tube V3 remain open. The winding tap N+1 is closed, and the load current flows out from the neutral point lead-out through the second transition resistor R2 and the fourth vacuum tube V4.

[0090] The second main current-carrying switch MC2 remains open, the second vacuum tube V2 remains open, and the fourth vacuum tube V4 remains closed. After the second vacuum tube V2 is completely extinguished, the second working state of connecting the moving contact of the changeover switch T with the second stationary contact 12 is switched to the third working state of the moving contact of the changeover switch being unavailable. The first main current-carrying switch MC1, the first vacuum tube V1, and the third vacuum tube V3 remain open. The winding tap N+1 is connected, and the load current flows out from the neutral point lead-out terminal through the second transition resistor R2 and the fourth vacuum tube V4.

[0091] The second main current-carrying switch MC2 remains open, the second vacuum tube V2 remains open, and the fourth vacuum tube V4 remains closed; the moving contact of the changeover switch T is idle and in the third operating state; the first main current-carrying switch MC1 and the first vacuum tube V1 remain open; the third vacuum tube V3 is turned on, and both winding tap N+1 and winding tap N are connected, with the load current I... N The current flows out from the neutral point terminal through the fourth vacuum tube V4, the second transition resistor R2, and the third vacuum tube V3 and the first transition resistor R1, respectively; the transition circuit forms a bridge, generating an interstage circulating current I. C The current I flowing through the fourth vacuum tube V4 V3 =I N / 2+I C The current I flowing through the third vacuum tube V3 V4 =I N / 2-I C ; where I C =U S / (R1+R2), the U S This is the voltage of the on-load tap changer stage.

[0092] The second main current flow switch MC2 remains disconnected, the second vacuum tube V2 remains disconnected, the fourth vacuum tube V4 is disconnected to generate an arc; the moving contact of the switch T is empty, in the third working state; the first main current flow switch MC1, the first vacuum tube V1 remain disconnected; the third vacuum tube V3 remains conducting, the winding tap N is connected, and the load current flows out from the neutral point through the first transition resistor R1 and the third vacuum tube V3.

[0093] The second main current flow switch MC2 remains disconnected, the second vacuum tube V2, the fourth vacuum tube V4 remain disconnected; the moving contact of the switch T is empty, in the third working state, the moving contact of the switch T is connected with the first static contact 11, in the first working state; the first main current flow switch MC1, the first vacuum tube V1 remain disconnected, the third vacuum tube V3 remains conducting, the winding tap N is connected, and the load current flows out from the neutral point through the first transition resistor R1 and the third vacuum tube V3.

[0094] The second main current flow switch MC2 remains disconnected, the second vacuum tube V2, the fourth vacuum tube V4 remain disconnected; the moving contact of the switch T is connected with the first static contact 11, in the first working state; the first main current flow switch MC1 remains disconnected, the third vacuum tube V3 remains conducting, the first vacuum tube V1 is conducting, the winding tap N is connected, and the load current flows out from the neutral point through the switch T, the first vacuum tube V1 and the third vacuum tube V3.

[0095] The second main current flow switch MC2 remains disconnected, the second vacuum tube V2, the fourth vacuum tube V4 remain disconnected; the moving contact of the switch T is connected with the first static contact 11, in the first working state; the first vacuum tube V1, the third vacuum tube V3 remain conducting, the first main current flow switch MC1 is conducting, the winding tap N is connected, and the load current flows out from the neutral point through the first main current flow switch MC1 from the first winding tap N.

[0096] When the on-load tap changer switches from the winding N tap to the winding N+1 tap, the transition circuit conversion procedure is as shown in Figure 11 .

[0097] When the on-load tap changer switches from the winding N+1 tap to the winding N tap, the transition circuit conversion procedure is as shown in Figure 12 .

[0098] When the internal switching elements in the on-load tap changer double-resistance reciprocating transition circuit are power electronic elements (such as thyristors or insulated gate bipolar transistors) or double-break vacuum tubes with controllable on-off function, the action timing of the switching elements and the voltage regulation method are consistent, and will not be described again.

[0099] In the embodiments of the present application, the switching tasks of the on-load tap changer transition circuit using vacuum tubes are shown in the following table:

[0100]

[0101] wherein, I N is the load current; U S is the on-load tap changer inter-stage voltage; R1 and R2 are both transition resistors.

[0102] As Figure 13 shown, only the single-break vacuum tube in Figure 1 is replaced by a power electronic element with controllable on-off, other elements are the same as those in Figure 1 , the action timing is consistent, and the function and effect are the same as the transition circuit shown in Figure 1 , which will not be repeated.

[0103] As Figure 14 shown, only the single-break vacuum tube in Figure 1 is replaced by a double-break vacuum tube, other elements are the same as those in Figure 1 , the action timing is consistent, and the function and effect are the same as the transition circuit shown in Figure 1 , which will not be repeated.

[0104] Specifically, the transition circuit of the present application further comprises a first disconnecting switch Z1 and a second disconnecting switch Z2; the second end of the first vacuum tube V1 is connected to the moving contact of the transfer switch T through the first disconnecting switch Z1, and the second end of the second vacuum tube V2 is connected to the moving contact of the transfer switch T through the second disconnecting switch Z2. As Figure 15 shown, the first disconnecting switch Z1 and the second disconnecting switch Z2 are added to the circuit to play the role of disconnecting the circuit connection when the switching element fails, and the addition of disconnecting switches in other positions also has similar effects.

[0105] The above is only the best specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered in the protection scope of the present application.

Claims

1. A load tap changer double resistance shuttle transition circuit, characterized by, The first main current flow switch, the second main current flow switch, the first switch element, the second switch element, the third switch element, the fourth switch element, the first transition resistance, the second transition resistance and the change-over switch are included. The first end of the first main current flow switch, the first end of the first transition resistance and the first end of the first switch element are connected with the first winding tap of the transformer voltage regulating winding; the first end of the second main current flow switch, the first end of the second transition resistance and the first end of the second switch element are connected with the second winding tap of the transformer voltage regulating winding. The second end of the first switch element is connected with the moving contact of the change-over switch through the first isolating switch. The second end of the second switch element is connected with the moving contact of the change-over switch through the second isolating switch.

2. A load-tap changer double-resistor shuttle transition circuit according to claim 1, characterized in that, The first end of the first main current flow switch, the first end of the first transition resistance and the first end of the first switch element are connected with the first winding tap of the transformer voltage regulating winding; the first end of the second main current flow switch, the first end of the second transition resistance and the first end of the second switch element are connected with the second winding tap of the transformer voltage regulating winding.

3. A load-tap changer double-resistor shuttle transition circuit according to claim 1, characterized in that, The second end of the first main current flow switch, the second end of the second main current flow switch, the second end of the third switch element and the second end of the fourth switch element are connected with the neutral point leading end of the on-load tap changer.

4. A load-tap changer double-resistor shuttle transition circuit according to claim 1, characterized in that, The first switch element, the second switch element, the third switch element and the fourth switch element are single-break vacuum tubes, double-break vacuum tubes or power electronic elements with controllable on-off function.

5. A load-tap changer double-resistor shuttle transition circuit according to claim 4, characterized in that, The power electronic element with controllable on-off function is a thyristor or an insulated gate bipolar transistor.

6. A load-tap changer double-resistor shuttle transition circuit according to claim 1, characterized in that, When the first main current flow switch, the first switch element and the third switch element are in the on state; the moving contact of the change-over switch T is connected with the first static contact, the second main current flow switch, the second switch element and the fourth switch element are in the off state, the load current flows out from the neutral point leading end through the first main current flow switch from the first winding tap; When the second main current flow switch, the second switch element and the fourth switch element are in the on state; the moving contact of the change-over switch is connected with the second static contact, the first main current flow switch, the first switch element and the third switch element are in the off state, the load current flows out from the neutral point leading end through the second main current flow switch from the second winding tap.

7. A method of voltage regulation based on the double-resistor reciprocating transition circuit of the load tap changer according to claim 1, characterized in that, The steps include: The first main current flow switch, the first switch element and the third switch element are in the conducting state; the moving contact of the change-over switch is connected with the first stationary contact, the second main current flow switch, the second switch element and the fourth switch element are in the open state; The first main current flow switch is opened, the first switch element is opened, the moving contact of the change-over switch is left idle, the fourth switch element is conducted, the third switch element is opened, the moving contact of the change-over switch is connected with the second stationary contact; the second switch element is conducted, the second main current flow switch is conducted; The load current flows out from the neutral point leading-out end of the second winding tap through the second main current flow switch, and the on-load tap changer is switched from the first winding tap to the second winding tap.

8. A method of voltage regulation based on the double-resistor reciprocating transition circuit of the load tap changer according to claim 1, characterized in that, The second main current flow switch, the second switch element and the fourth switch element are in the conducting state; the moving contact of the change-over switch is connected with the second stationary contact, the first main current flow switch, the first switch element and the third switch element are in the open state; the second main current flow switch is opened, the second switch element is opened, the moving contact of the change-over switch is left idle, the third switch element is conducted, the fourth switch element is opened, the moving contact of the change-over switch is connected with the first stationary contact, the first switch element is conducted, the first main current flow switch is conducted, and the load current flows out from the neutral point leading-out end of the second winding tap through the first main current flow switch, and the on-load tap changer is switched from the second winding tap to the first winding tap.

Images