On-load tap-changer transition circuit and voltage regulating method

Abstract

The invention discloses an on-load tap-changer transition circuit and a voltage regulating method. A first tap gear of a transformer voltage regulating winding of the transition circuit is connected with a first main contact, a first transition resistor and a first moving contact of a change-over switch; a second tapping gear of the voltage regulating winding of the transformer is respectively connected with the second transition resistor, the first switch element and the second main contact; the other end of the first transition resistor is connected with one end of the second switch element; one end of the third switch element is connected with the first switch element and the change-over switch respectively; the other end of the second transition resistor is connected with a second moving contact of the change-over switch; and the other ends of the first main contact, the second main contact, the second switch element and the third switch element are connected with a neutral point leading-out end of the on-load tap-changer. According to the on-load tap-changer transition circuit and the voltage regulation method provided by the embodiment of the invention, the vacuum contacts undertake switching tasks in turn, so that the fault probability is reduced, and the safety of a power system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to an on-load tap changer transition circuit and a voltage regulation method. Background Art

[0002] On-load tap-changers are key components within power transformers. They operate under both energized and loaded conditions, changing the effective turns ratio by connecting multiple taps in the transformer windings, thereby regulating the output voltage without interrupting the load current. The transition circuit, the core of the on-load tap-changer, has a direct impact on switching reliability, failure rate, and electrical life.

[0003] However, due to the unreasonable design of the existing on-load tap-changer transition circuit, the separation and closing of mechanical contacts under high voltage or high current conditions are prone to arcing, and the mechanical contacts and switching elements are prone to wear during frequent switching, seriously affecting the safety of the power system.

[0004] Therefore, how to optimize the design of the on-load tap changer transition circuit to improve the safety of the power system has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The present invention provides an on-load tap changer transition circuit and a voltage regulation method to solve the technical problems that the design of the existing on-load tap changer transition circuit is not reasonable, the separation and closing of mechanical contacts under high voltage or high current conditions easily generate arcs, and the mechanical contacts and switch elements are easily worn during frequent switching, which seriously affects the safety of the power system.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides an on-load tap changer transition circuit, comprising a first main contact, a second main contact, a first switching element, a second switching element, a third switching element, a transfer switch, a first transition resistor, and a second transition resistor;

[0007] The first tap position of the transformer voltage regulating winding is respectively connected to the first main contact, the first transition resistor, and the first moving contact of the transfer switch; the second tap position of the transformer voltage regulating winding is respectively connected to the second transition resistor, the first switching element, and the second main contact;

[0008] The other end of the first transition resistor is connected to one end of the second switching element, and one end of the third switching element is connected to the first switching element and the transfer switch respectively; the other end of the second transition resistor is connected to the second moving contact of the transfer switch;

[0009] The other ends of the first main contact, the second main contact, the second switching element, and the third switching element are all connected to the neutral point lead-out terminal of the on-load tap changer.

[0010] As one preferred solution, when the first main contact, the third switching element, and the second switching element are all in the on state, the first switching element and the second main contact are both in the off state, and the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out of the neutral point lead-out terminal through the first main contact;

[0011] When the second main contact, the first switching element, and the third switching element are all in the on state, and the first main contact and the second switching element are all in the off state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the second main contact.

[0012] As one preferred solution, when the first main contact, the second main contact, and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, and the transfer switch is conductively connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially passes through the transfer switch and the third switching element and flows out of the neutral point lead-out terminal;

[0013] When the first switching element and the third switching element are both in the on state, the first main contact, the second main contact, and the second switching element are all in the off state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current sequentially passes through the first switching element and the third switching element and flows out of the neutral point lead-out terminal.

[0014] As one preferred solution, when the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, and the second switching element is all in the disconnected state, and the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially flows through the first transition resistor and the second switching element and out of the neutral point lead-out terminal;

[0015] When the third switching element is in the on state, the first main contact, the second main contact, the first switching element, and the second switching element are all in the off state, and when the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out of the neutral point lead-out terminal through the second transition resistor and the third switching element in sequence.

[0016] As one preferred solution, when the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, the second switching element is in the on state, and the transfer switch is conductively connected to the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially flows through the first transition resistor and the second switching element and out of the neutral point lead-out terminal;

[0017] When the second switching element and the third switching element are both in the on state, the first main contact, the second main contact, and the first switching element are all in the off state, and the transfer switch is in conduction with the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position and the second tap position, respectively, and the load current flows out of the neutral point lead-out terminal through the first path and the second path, respectively; wherein the first path passes through the first transition resistor and the second switching element in sequence, and the second path passes through the second transition resistor, the transfer switch, and the third switching element in sequence.

[0018] As one preferred solution, when the first main contact, the second main contact, and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, and the transfer switch is in conduction with the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position and the second tap position, respectively, and the load current flows out of the neutral point lead-out terminal through a first path and a second path, respectively; wherein the first path sequentially passes through the first transition resistor and the second switching element, and the second path sequentially passes through the second transition resistor, the transfer switch, and the third switching element;

[0019] When the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, the second switching element is in the on state, and the transfer switch is conductively connected to the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially flows through the first transition resistor and the second switching element and out of the neutral point lead-out terminal.

[0020] As one preferred solution, when the first main contact, the second main contact, the first switching element, and the second switching element are all in the disconnected state, the third switching element is in the on state, and the transfer switch is conductively connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tapping position, and the load current sequentially flows through the second transition resistor, the transfer switch, and the third switching element and out of the neutral point lead-out terminal;

[0021] When the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, the second switching element is in the on state, and the transfer switch is conductively connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially flows through the first transition resistor and the second switching element and out of the neutral point lead-out terminal.

[0022] As one preferred solution, when the first main contact, the second main contact, and the second switching element are all in the disconnected state, the first switching element and the third switching element are both in the on state, and the transfer switch is conductively connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tapping position, and the load current sequentially passes through the first switching element and the third switching element and flows out of the neutral point lead-out terminal;

[0023] When the first main contact, the second main contact, and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, and the transfer switch is conductively connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially passes through the transfer switch and the third switching element and flows out of the neutral point lead-out terminal.

[0024] As one preferred solution, when the first main contact and the second switching element are both in the disconnected state, the first switching element, the second main contact, and the third switching element are all in the on state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tapping position, and the load current flows out of the neutral point lead-out terminal through the second main contact;

[0025] When the first switching element and the second main contact are both in the disconnected state, the first main contact, the second switching element, and the third switching element are all in the on state, and the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out of the neutral point lead-out terminal through the first main contact.

[0026] Another embodiment of the present invention provides an on-load tap changer voltage regulation method, which is applied to the on-load tap changer transition circuit as described above, comprising:

[0027] When the transition circuit is in the first tap state, the first main contact and the third switch element are disconnected in sequence; the transfer switch is controlled to disconnect from the first moving contact and connect with the second moving contact; the third switch element is connected, the second switch element is disconnected, the first switch element is connected, and the second main contact is connected in sequence, so that the on-load tap changer switches from the first tap position to the second tap position; wherein the first tap state is that the first main contact, the third switch element, and the second switch element are all in the on state, the first switch element and the second main contact are both in the off state, and the transfer switch is connected to the first moving contact;

[0028] When the transition circuit is in the second tap state, the first switching element is disconnected, the second switching element is turned on, and the third switching element is disconnected in sequence, the transfer switch is controlled to disconnect from the second moving contact and to be connected to the first moving contact, the third switching element is turned on in sequence, and the first main contact is turned on, so that the on-load tap changer switches from the second tap position to the first tap position; wherein, the second tap state is that the first main contact and the second switching element are both in the disconnected state, the first switching element, the second main contact, and the third switching element are all in the on state, and the transfer switch is connected to the second moving contact.

[0029] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0030] When the transition circuit is in the first tap state, the first main contact is disconnected and the third switch element is disconnected in sequence; the transfer switch is controlled to disconnect from the first moving contact and connect with the second moving contact; the third switch element is connected, the second switch element is disconnected, the first switch element is connected, and the second main contact is connected in sequence, so that the on-load tap changer switches from the first tap gear to the second tap gear; wherein, the first tap state is that the first main contact, the third switch element, and the second switch element are all in the on state, the first switch element and the second main contact are both in the off state, and the transfer switch is connected to the first moving contact; when the transition circuit is in the second tap state, the first switch element is disconnected, the second switch element is connected, and the third switch element is disconnected in sequence, and the transfer switch is controlled to connect to the second moving contact. Disconnect, and conduct with the first moving contact, and turn on the third switching element and the first main contact in sequence, so that the on-load tap changer is switched from the second tap gear to the first tap gear; wherein, the second tap state is that the first main contact and the second switching element are both in the disconnected state; the vacuum contacts take turns to undertake the switching task, thereby avoiding excessive wear of a single contact, improving the safety of the power system, and extending the life of the equipment; using two transition resistors to share the current, reducing the heat generation of a single resistor, and improving the heat dissipation efficiency, providing ample time for the arc ignition and arc extinction process in the vacuum contact, reducing the damage to the contact by the arc, and avoiding sudden changes in current and voltage by gradually switching the contacts and switching elements, ensuring the stability of the system, and further improving the safety of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figures 1 to 8 Schematic diagram of a positive sequence switching process of an on-load tap changer transition circuit switching from a first tap state to a second tap state in one embodiment of the present invention;

[0032] Figure 9 A schematic diagram of a switching element of an on-load tap changer transition circuit according to one embodiment of the present invention, wherein the switching element is a power electronic element;

[0033] Figure 10 A schematic diagram of a double-break vacuum contact as a switching element of an on-load tap changer transition circuit according to one embodiment of the present invention;

[0034] Figure 11 This is a timing diagram of switch on / off positive sequence switching control of an on-load tap changer voltage regulation method in one embodiment of the present invention;

[0035] Figure 12 This is a timing diagram of switch on-off reverse switching control of an on-load tap changer voltage regulation method in one embodiment of the present invention.

[0036] Reference numerals:

[0037] Among them, MC1, first main contact; MC2, second main contact; V1, first switching element; V2, second switching element; V3, third switching element; T1, transfer switch; R1, first transition resistor; R2, second transition resistor; I1, first moving contact of transfer switch T1; I2, second moving contact of transfer switch T1; N, first tap position; N+1, second tap position. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0039] In the description of this application, the terms "first," "second," "third," etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first," "second," "third," etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the two components. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are for illustrative purposes only, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. Those skilled in the art will understand the specific meanings of the above terms in this application in specific circumstances.

[0042] An embodiment of the present invention provides an on-load tap changer transition circuit, including a first main contact, a second main contact, a first switching element, a second switching element, a third switching element, a transfer switch, a first transition resistor, and a second transition resistor.

[0043] The first tap position of the transformer's voltage regulating winding is respectively connected to the first main contact, the first transition resistor, and the first moving contact of the transfer switch; the second tap position of the transformer's voltage regulating winding is respectively connected to the second transition resistor, the first switching element, and the second main contact; the other end of the first transition resistor is connected to one end of the second switching element, and one end of the third switching element is respectively connected to the first switching element and the transfer switch; the other end of the second transition resistor is connected to the second moving contact of the transfer switch; and the other ends of the first main contact, the second main contact, the second switching element, and the third switching element are all connected to the neutral point lead-out terminal of the on-load tap changer.

[0044] For details, see Figures 1 to 8 , Figures 1 to 8 The diagram shows the positive sequence switching process of an on-load tap changer transition circuit switching from a first tap state to a second tap state in one embodiment of the present invention. MC1 is the first main contact, MC2 is the second main contact, V1 is the first switching element, V2 is the second switching element, V3 is the third switching element, T1 is the transfer switch, R1 is the first transition resistor, R2 is the second transition resistor, I1 is the first moving contact of transfer switch T1, I2 is the second moving contact of transfer switch T1, N is the first tap position, and N+1 is the second tap position.

[0045] It should be noted that in the on-load tap changer transition circuit provided in this embodiment, vacuum contacts take turns to perform switching tasks, thereby reducing the probability of failure; two transition resistors are used in the transition circuit, which reduces the heat generated by a single resistor, facilitates design and installation, and ensures insulation distance.

[0046] In one embodiment, the positive sequence switching process of switching from the first tap state to the second tap state includes a first positive sequence switching process to an eighth positive sequence switching process.

[0047] When the transition circuit is in the first positive sequence switching process from the first tap state to the second tap state, see Figure 1, the first main contact, the third switching element and the second switching element are all in the on state, the first switching element and the second main contact are both in the off state, the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the first main contact.

[0048] When the transition circuit is in the second positive sequence switching process from the first tap state to the second tap state, see Figure 2 , the first main contact, the second main contact and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the transfer switch and the third switching element in sequence.

[0049] When the transition circuit is in the third positive sequence switching process from the first tap state to the second tap state, see Figure 3 , the first main contact, the second main contact, the first switching element and the third switching element are all in the disconnected state, the second switching element is all in the disconnected state, the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the first transition resistor and the second switching element in sequence.

[0050] When the transition circuit is in the fourth positive sequence switching process from the first tap state to the second tap state, see Figure 4 , the first main contact, the second main contact, the first switching element and the third switching element are all in the disconnected state, the second switching element is in the on state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the first transition resistor and the second switching element in sequence.

[0051] When the transition circuit is in the fifth positive sequence switching process from the first tap state to the second tap state, see Figure 5 The first main contact, the second main contact, and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position and the second tap position, respectively, and the load current flows out from the neutral point lead-out terminal through the first path and the second path respectively; wherein, the first path passes through the first transition resistor and the second switching element in sequence, and the second path passes through the second transition resistor, the transfer switch, and the third switching element in sequence.

[0052] When the transition circuit is in the sixth positive sequence switching process from the first tap state to the second tap state, see Figure 6, the first main contact, the second main contact, the first switching element and the second switching element are all in the disconnected state, the third switching element is in the on state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the second transition resistor, the transfer switch and the third switching element in sequence.

[0053] When the transition circuit is in the seventh positive sequence switching process from the first tap state to the second tap state, see Figure 7 , the first main contact, the second main contact and the second switching element are all in the disconnected state, the first switching element and the third switching element are both in the on state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the first switching element and the third switching element in sequence.

[0054] When the transition circuit is in the eighth positive sequence switching process from the first tap state to the second tap state, see Figure 8 , the first main contact and the second switching element are both in the disconnected state, the first switching element, the second main contact and the third switching element are all in the on state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the second main contact.

[0055] In one embodiment, the reverse switching process of switching from the second tap state to the first tap state includes a first reverse switching process to an eighth reverse switching process.

[0056] When the transition circuit is in the first reverse switching process from the second tap state to the first tap state, the second main contact, the first switching element, and the third switching element are all in the on state, the first main contact and the second switching element are both in the off state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the second main contact.

[0057] When the transition circuit is in the second reverse switching process from the second tap state to the first tap state, the first switching element and the third switching element are both in the on state, the first main contact, the second main contact, and the second switching element are all in the off state, the transfer switch and the second moving contact are connected, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the first switching element and the third switching element in sequence.

[0058] When the transition circuit is in the third reverse switching process from the second tap state to the first tap state, the third switching element is in the on state, the first main contact, the second main contact, the first switching element and the second switching element are all in the off state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the second transition resistor and the third switching element in sequence.

[0059] When the transition circuit is in a fourth reverse switching process from the second tap state to the first tap state, the second switching element and the third switching element are both in the on state, the first main contact, the second main contact, and the first switching element are all in the off state, the transfer switch is in conduction with the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position and the second tap position, respectively, and the load current flows out from the neutral point lead-out terminal through the first path and the second path, respectively; wherein the first path passes through the first transition resistor and the second switching element in sequence, and the second path passes through the second transition resistor, the transfer switch, and the third switching element in sequence.

[0060] When the transition circuit is in the fifth reverse switching process from the second tap state to the first tap state, the first main contact, the second main contact, the first switching element and the third switching element are all in the disconnected state, the second switching element is in the on state, the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the first transition resistor and the second switching element in sequence.

[0061] When the transition circuit is in the sixth reverse switching process from the second tap state to the first tap state, the first main contact, the second main contact, the first switching element and the third switching element are all in the disconnected state, the second switching element is in the on state, the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the first transition resistor and the second switching element in sequence.

[0062] When the transition circuit is in the seventh reverse switching process from the second tap state to the first tap state, the first main contact, the second main contact and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the transfer switch and the third switching element in sequence.

[0063] When the transition circuit is in the eighth reverse switching process from the second tap state to the first tap state, the first switching element and the second main contact are both in the disconnected state, the first main contact, the second switching element and the third switching element are all in the on state, the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out from the neutral point lead-out terminal through the first main contact.

[0064] It should be noted that the first switching element, the second switching element, and the third switching element are at least one of a single-break vacuum contactor, a double-break vacuum contactor, or a power electronic element with a controllable on / off function. The power electronic element with a controllable on / off function is an IGBT or a MOSFET, etc.

[0065] In one embodiment, the first switching element, the second switching element and the third switching element are all power electronic elements. For details, see Figure 9 , Figure 9 A schematic diagram showing a power electronic component used as the switching element in a transition circuit of an on-load tap changer according to one embodiment of the present invention is shown. MC1 is the first main contact, MC2 is the second main contact, V1 is the first switching element, V2 is the second switching element, V3 is the third switching element, T1 is the transfer switch, R1 is the first transition resistor, R2 is the second transition resistor, I1 is the first moving contact of transfer switch T1, I2 is the second moving contact of transfer switch T1, N is the first tap position, and N+1 is the second tap position.

[0066] In another embodiment, the first switch element, the second switch element and the third switch element all use double-break vacuum contacts. For details, see Figure 10 , Figure 10 A schematic diagram illustrating a double-break vacuum contact as the switching element of an on-load tap-changer transition circuit in one embodiment of the present invention is shown. MC1 is the first main contact, MC2 is the second main contact, V1 is the first switching element, V2 is the second switching element, V3 is the third switching element, T1 is the transfer switch, R1 is the first transition resistor, R2 is the second transition resistor, I1 is the first moving contact of transfer switch T1, I2 is the second moving contact of transfer switch T1, N is the first tap position, and N+1 is the second tap position.

[0067] Another embodiment of the present invention provides an on-load tap changer voltage regulation method, which is applied to the on-load tap changer transition circuit as described above. For details, see Figures 11 and 12 , Figure 11 The figure shows a switch on-off positive sequence switching control timing diagram of a method for regulating voltage of an on-load tap changer according to one embodiment of the present invention, i.e., the switch on-off timing control for controlling the transition circuit to switch from a first tap state to a second tap state. Figure 12 This diagram shows the reverse switching control timing diagram for an on-load tap changer voltage regulation method according to one embodiment of the present invention. This diagram illustrates the switching timing control for controlling the transition circuit from a first tap state to a second tap state. MC1 represents the first main contact, MC2 represents the second main contact, V1 represents the first switching element, V2 represents the second switching element, V3 represents the third switching element, and T1 represents the transfer switch.

[0068] This embodiment provides a method for regulating voltage of an on-load tap changer, including:

[0069] When the transition circuit is in the first tap state, the first main contact and the third switching element are disconnected in sequence; the transfer switch is controlled to disconnect from the first moving contact and connect with the second moving contact; the third switching element is connected, the second switching element is disconnected, the first switching element is connected, and the second main contact is connected in sequence, so that the on-load tap changer switches from the first tap position to the second tap position; wherein the first tap state is that the first main contact, the third switching element, and the second switching element are all in the on state, the first switching element and the second main contact are both in the off state, and the transfer switch is connected with the first moving contact;

[0070] When the transition circuit is in the second tap state, the first switching element is disconnected, the second switching element is turned on, and the third switching element is disconnected in sequence, and the transfer switch is controlled to disconnect from the second moving contact and to be connected to the first moving contact. The third switching element is turned on and the first main contact is turned on in sequence, so that the on-load tap changer switches from the second tap position to the first tap position; wherein, the second tap state is that the first main contact and the second switching element are both in the disconnected state, the first switching element, the second main contact and the third switching element are all in the on state, and the transfer switch is connected to the second moving contact.

[0071] Preferably, an isolating switch is installed on the line where the existing vacuum contact is located to achieve electrical isolation and protection.

[0072] The on-load tap changer transition circuit and voltage regulation method provided by the embodiments of the present invention have the following advantages over the prior art:

[0073] When the transition circuit is in the first tap state, the first main contact is disconnected and the third switch element is disconnected in sequence; the transfer switch is controlled to disconnect from the first moving contact and connect with the second moving contact; the third switch element is connected, the second switch element is disconnected, the first switch element is connected, and the second main contact is connected in sequence, so that the on-load tap changer switches from the first tap gear to the second tap gear; wherein, the first tap state is that the first main contact, the third switch element, and the second switch element are all in the on state, the first switch element and the second main contact are both in the off state, and the transfer switch is connected to the first moving contact; when the transition circuit is in the second tap state, the first switch element is disconnected, the second switch element is connected, and the third switch element is disconnected in sequence, and the transfer switch is controlled to connect to the second moving contact. Disconnect, and conduct with the first moving contact, and turn on the third switching element and the first main contact in sequence, so that the on-load tap changer is switched from the second tap gear to the first tap gear; wherein, the second tap state is that the first main contact and the second switching element are both in the disconnected state; the vacuum contacts take turns to undertake the switching task, thereby avoiding excessive wear of a single contact, improving the safety of the power system, and extending the life of the equipment; using two transition resistors to share the current, reducing the heat generation of a single resistor, and improving the heat dissipation efficiency, providing ample time for the arc ignition and arc extinction process in the vacuum contact, reducing the damage to the contact by the arc, and avoiding sudden changes in current and voltage by gradually switching the contacts and switching elements, ensuring the stability of the system, and further improving the safety of the power system.

[0074] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An on-load tap changer transition circuit, characterized in that: It includes a first main contact, a second main contact, a first switching element, a second switching element, a third switching element, a transfer switch, a first transition resistor and a second transition resistor; The first tap position of the transformer voltage regulating winding is respectively connected to the first main contact, the first transition resistor, and the first moving contact of the transfer switch; the second tap position of the transformer voltage regulating winding is respectively connected to the second transition resistor, the first switch element, and the second main contact; The other end of the first transition resistor is connected to one end of the second switching element, and one end of the third switching element is connected to the first switching element and the transfer switch respectively; the other end of the second transition resistor is connected to the second moving contact of the transfer switch; The other ends of the first main contact, the second main contact, the second switching element, and the third switching element are all connected to the neutral point lead-out terminal of the on-load tap changer.

2. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact, the third switching element, and the second switching element are all in the on state, the first switching element and the second main contact are both in the off state, and the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out of the neutral point lead-out terminal through the first main contact; When the second main contact, the first switching element, and the third switching element are all in the on state, and the first main contact and the second switching element are all in the off state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out from the neutral point lead-out terminal through the second main contact.

3. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact, the second main contact, and the first switching element are all in the disconnected state, and the second switching element and the third switching element are both in the on state, and the transfer switch is conductively connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially flows through the transfer switch and the third switching element and out of the neutral point lead-out terminal; When the first switching element and the third switching element are both in the on state, the first main contact, the second main contact, and the second switching element are all in the off state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current sequentially passes through the first switching element and the third switching element and flows out of the neutral point lead-out terminal.

4. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, and the second switching element is all in the disconnected state, and the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out of the neutral point lead-out terminal through the first transition resistor and the second switching element in sequence; When the third switching element is in the on state, the first main contact, the second main contact, the first switching element, and the second switching element are all in the off state, and when the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tap position, and the load current flows out of the neutral point lead-out terminal through the second transition resistor and the third switching element in sequence.

5. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, the second switching element is in the on state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out of the neutral point lead-out terminal through the first transition resistor and the second switching element in sequence; When the second switching element and the third switching element are both in the on state, the first main contact, the second main contact, and the first switching element are all in the off state, and the transfer switch is in conduction with the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position and the second tap position, respectively, and the load current flows out of the neutral point lead-out terminal through the first path and the second path, respectively; wherein the first path passes through the first transition resistor and the second switching element in sequence, and the second path passes through the second transition resistor, the transfer switch, and the third switching element in sequence.

6. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact, the second main contact, and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, and the transfer switch is in conduction with the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position and the second tap position, respectively, and the load current flows out of the neutral point lead-out terminal through the first path and the second path, respectively; wherein the first path sequentially passes through the first transition resistor and the second switching element, and the second path sequentially passes through the second transition resistor, the transfer switch, and the third switching element; When the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, the second switching element is in the on state, and the transfer switch is conductively connected to the second moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially flows through the first transition resistor and the second switching element and out of the neutral point lead-out terminal.

7. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact, the second main contact, the first switching element, and the second switching element are all in the disconnected state, the third switching element is in the on state, and the transfer switch is conductively connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tapping position, and the load current flows out of the neutral point lead-out terminal through the second transition resistor, the transfer switch, and the third switching element in sequence; When the first main contact, the second main contact, the first switching element, and the third switching element are all in the disconnected state, the second switching element is in the on state, and the transfer switch is conductively connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially flows through the first transition resistor and the second switching element and out of the neutral point lead-out terminal.

8. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact, the second main contact, and the second switching element are all in the disconnected state, the first switching element and the third switching element are both in the on state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tapping position, and the load current flows out of the neutral point lead-out terminal through the first switching element and the third switching element in sequence; When the first main contact, the second main contact, and the first switching element are all in the disconnected state, the second switching element and the third switching element are both in the on state, and the transfer switch is conductively connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current sequentially passes through the transfer switch and the third switching element and flows out of the neutral point lead-out terminal.

9. The on-load tap changer transition circuit according to claim 1, characterized in that: When the first main contact and the second switching element are both in the disconnected state, the first switching element, the second main contact, and the third switching element are all in the on state, and the transfer switch is connected to the second moving contact, the tap selector of the on-load tap changer is connected to the second tapping position, and the load current flows out of the neutral point lead-out terminal through the second main contact; When the first switching element and the second main contact are both in the disconnected state, the first main contact, the second switching element, and the third switching element are all in the on state, and the transfer switch is connected to the first moving contact, the tap selector of the on-load tap changer is connected to the first tap position, and the load current flows out of the neutral point lead-out terminal through the first main contact.

10. A method for regulating voltage of an on-load tap changer, applied to an on-load tap changer transition circuit according to any one of claims 1 to 9, characterized in that: The method comprises: When the transition circuit is in the first tap state, the first main contact and the third switch element are disconnected in sequence; the transfer switch is controlled to disconnect from the first moving contact and connect with the second moving contact; the third switch element is connected, the second switch element is disconnected, the first switch element is connected, and the second main contact is connected in sequence, so that the on-load tap changer switches from the first tap position to the second tap position; wherein the first tap state is that the first main contact, the third switch element, and the second switch element are all in the on state, the first switch element and the second main contact are both in the off state, and the transfer switch is connected to the first moving contact; When the transition circuit is in the second tap state, the first switching element is disconnected, the second switching element is turned on, and the third switching element is disconnected in sequence, the transfer switch is controlled to disconnect from the second moving contact and to be connected to the first moving contact, the third switching element is turned on in sequence, and the first main contact is turned on, so that the on-load tap changer switches from the second tap position to the first tap position; wherein, the second tap state is that the first main contact and the second switching element are both in the disconnected state, the first switching element, the second main contact, and the third switching element are all in the on state, and the transfer switch is connected to the second moving contact.

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