Arc-free on-load tap changer, switching control method and electrical equipment

Abstract

The present invention belongs to the technical field of power transmission and transformation in power systems, and provides an arc-free on-load tap changer, a switching control method, and electrical equipment. The arc-free on-load tap changer includes at least two main switches, two transfer switches, and two thyristor auxiliary modules; the two thyristor auxiliary modules are connected in parallel with the originally closed main switch or the main switch to be closed according to the required timing during the main switch switching process; the main switch and transfer switch are both rotary shaft switches, the moving contacts of the main switch and transfer switch are both arranged on a rotating shaft, the corresponding static contacts of the main switch and transfer switch are connected to the corresponding transformer tap, and the moving contacts are connected to the coaxial static contacts during the process of rotating with the rotating shaft; the corresponding main switches, transfer switches, and control switches are controlled to open and close according to a preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and the opening and closing process of each switch is arc-free.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transmission and transformation of electric power systems, and in particular relates to an arc-free on-load tap changer, a switching control method and electrical equipment. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] To switch a transformer's tap from one voltage to another while the transformer is under load (under load), while ensuring that power users remain powered, an on-load tapchanger (OLT) is required. An OLT is a voltage-regulating device designed to change the connection position of a transformer's windings, operating while the transformer is excited or under load. Its basic principle is to switch between taps in the transformer winding without interrupting the load current, thereby changing the number of turns in the winding, or in other words, the transformer's voltage ratio, ultimately achieving voltage regulation.

[0004] Existing on-load tap changers generally use a resistance transition method to achieve the switching process between two different voltage taps. However, the resistance transition method has the disadvantage of arcing during the switching process.

[0005] Patent documents with application numbers CN2012105791965, CN2013105976862, and CN2014102602640 respectively provide different arc-free on-load tap-changers. However, since oil-immersed on-load tap-changers are suitable for being driven by a rotating shaft, the inventors have discovered that the devices proposed in the above-mentioned application documents are mainly used in situations where the circuit is composed of contactors or relay contacts. Arc-free on-load tap-changers composed of contactors or relays are not suitable for use with oil-immersed transformers.

[0006] The on-load tap changer solution provided in patent document with application number CN2018102904704 has a rotating shaft driven structure. However, the inventors found that the patent document still has a complex operating structure because various switches are distributed on two or three asynchronous rotating shafts. When one rotating shaft needs to rotate, the other rotating shaft needs to be stationary. In addition, there is a lack of a coordinated control mechanism between the rotating shafts, a matching scheme for the moving contacts and static contacts of the rotating shafts, and a driving scheme for controlling the switches. Summary of the Invention

[0007] To address the technical problems in the aforementioned background technology, the present invention provides an arc-free on-load tap changer, a switching control method, and an electrical device. The arc-free on-load tap changer is suitable for oil-immersed transformers driven by a rotating shaft and has the advantages of a simple operating structure and a short switching process time.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A first aspect of the present invention provides an arc-free on-load tap changer.

[0010] In one or more embodiments, a first arc-free on-load tap-changer structure is provided, comprising at least two main switches, two transfer switches, and two thyristor auxiliary modules; each thyristor auxiliary module comprises two control switches; the two main switches comprise an originally closed main switch and a main switch to be closed; the main switches are connected to corresponding circuits of a voltage regulating coil via corresponding transformer taps; and the two thyristor auxiliary modules are connected in parallel with the originally closed main switch or the main switch to be closed according to a required timing during the main switch switching process;

[0011] The main switch and transfer switch are both rotary shaft switches, with their moving contacts arranged on the rotating shaft. The corresponding static contacts of the main switch and transfer switch are connected to the corresponding transformer taps. The moving contacts connect with the coaxial static contacts as the rotating shaft rotates. The corresponding main switches, transfer switches, and control switches are controlled to open and close according to a preset timing sequence to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arcing during the opening and closing process of each switch.

[0012] As an implementation manner, one end of each of the two thyristor auxiliary modules is suspended or connected in parallel with the originally closed main switch before the main switch is switched, and the voltages across both ends of the two thyristor auxiliary modules are zero.

[0013] As an embodiment, the control switch is also a rotary shaft switch, and the moving contact of the control switch is also arranged on the rotating shaft.

[0014] As an embodiment, the static contacts of all main switches and transfer switches are divided into at least two groups, and each group of static contacts is installed on a corresponding track, and the tracks are all centered on the rotation axis and are fixed.

[0015] As an implementation method, each group of static contacts has the same number of static contacts.

[0016] As an implementation method, each set of static contacts is installed on a corresponding track with equal arcs.

[0017] As an implementation method, when the static contacts of all main switches and transfer switches are divided into two groups, the relationship between the arcs of the static contacts on the two tracks is:

[0018] 0<ΔW <W1<0.5W<W2;

[0019] ΔW=(W-W2);

[0020] Wherein: W and W1 are the radians between the center positions of the static contacts on the first track and the radian of each static contact respectively; W2 and ΔW are the radians of the static contacts on the second track and the radian of the static contact gap respectively.

[0021] As an embodiment, before the main switch is switched, the normal operating state of the arc-free on-load tap changer is:

[0022] A moving contact on the rotating shaft is located on the center line of a static contact, and the other moving contacts are respectively located on the center lines of the gaps between the static contacts.

[0023] As an embodiment, when there are three moving contacts on the rotating shaft, the first moving contact and the second moving contact are arranged on both sides of the third moving contact, and the arc relationship of the three moving contacts is:

[0024] 0<ΔW 动 <W 1动 <0.5W <W 2动 ;

[0025] ΔW 动 =(WW 2动 );

[0026] Where: W is the arc between the center positions of the static contacts on the first track, W 1动 、W 2动 is the arc distance between the first moving contact and the second moving contact, ΔW 动 is the radian of the gap between the second moving contacts.

[0027] As an implementation method, the curvature of the static contact is greater than the curvature of the movable contact.

[0028] As an implementation method, the curvature of the static contact is less than or equal to the curvature of the moving contact.

[0029] As an implementation manner, the opening and closing of the control switch is controlled by a control mechanism.

[0030] As an implementation method, the control mechanism is a mechanical linkage mechanism.

[0031] As an embodiment, the mechanical linkage mechanism includes a deflection shaft, which is fixed on the rotating shaft and rotates with the rotating shaft. The deflection shaft is equipped with a lever arm and a spring arm that can rotate around the deflection shaft. There is a contact at one end of the spring arm. The contact contacts or disengages with the corresponding control switch as the rotating shaft rotates, causing the corresponding control switch to open and close.

[0032] As an embodiment, the control mechanism is implemented by a transfer switch driven by a rotating shaft.

[0033] As an implementation method, the two thyristor auxiliary modules have the same structure.

[0034] As an implementation method, each thyristor auxiliary module includes a pair of reverse-parallel thyristors; an RC series circuit is connected in parallel at both ends of the reverse-parallel thyristors; a capacitor, a resistor and a diode are connected in sequence between the gate and cathode of each thyristor; the positive electrode of the diode is connected to the cathode of the corresponding thyristor, and the negative electrode of the diode is connected to the gate of the corresponding thyristor; the gates of the two reverse-parallel thyristors are also connected in series with a control switch through a full-bridge rectifier circuit; two Zener diodes and a resistor are also connected in series between the gates of the two reverse-parallel thyristors and another control switch; wherein the two Zener diodes are connected in reverse series; after the Zener diode and the resistor are connected in series, they are connected to the output end of the full-bridge rectifier circuit, the negative electrode of the Zener diode corresponds to the positive output end of the full-bridge rectifier circuit, and the positive electrode of the Zener diode corresponds to the negative output end of the full-bridge rectifier circuit.

[0035] The present invention provides a second arc-free on-load tap changer, characterized by comprising at least two main switches, two transfer switches, and two thyristor auxiliary modules; each thyristor auxiliary module includes two control switches; the two main switches include one originally closed main switch and one to be closed; the main switches are connected to corresponding circuits of the voltage regulating coil via corresponding transformer taps; and the two thyristor auxiliary modules are connected to the originally closed main switch or the to-be-closed main switch according to the required timing during the main switch switching process;

[0036] The main switch and transfer switch are both rotary shaft switches, in which the main switch and the corresponding transfer switch are linked and rotate synchronously; the corresponding main switch, transfer switch and control switch are controlled to open and close according to a preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arc during the opening and closing process of each switch.

[0037] As an implementation method, the control mechanism is a mechanical linkage mechanism.

[0038] As an embodiment, the mechanical linkage mechanism includes a deflection shaft, which is fixed on the rotating shaft and rotates with the rotating shaft. The deflection shaft is equipped with a lever arm and a spring arm that can rotate around the deflection shaft. There is a contact at one end of the spring arm. The contact contacts or disengages with the corresponding control switch as the rotating shaft rotates, causing the corresponding control switch to open and close.

[0039] As an embodiment, the control mechanism is implemented by a transfer switch driven by a rotating shaft.

[0040] As an implementation method, the two thyristor auxiliary modules have the same structure.

[0041] As an implementation method, each thyristor auxiliary module includes a pair of reverse-parallel thyristors; an RC series circuit is connected in parallel at both ends of the reverse-parallel thyristors; a capacitor, a resistor and a diode are connected in sequence between the gate and cathode of each thyristor; the positive electrode of the diode is connected to the cathode of the corresponding thyristor, and the negative electrode of the diode is connected to the gate of the corresponding thyristor; the gates of the two reverse-parallel thyristors are also connected in series with a control switch through a full-bridge rectifier circuit; two Zener diodes and a resistor are also connected in series between the gates of the two reverse-parallel thyristors and another control switch; wherein the two Zener diodes are connected in reverse series; after the Zener diode and the resistor are connected in series, they are connected to the output end of the full-bridge rectifier circuit, the negative electrode of the Zener diode corresponds to the positive output end of the full-bridge rectifier circuit, and the positive electrode of the Zener diode corresponds to the negative output end of the full-bridge rectifier circuit.

[0042] The present invention provides a third type of arc-free on-load tap changer, comprising at least two main switches, two transfer switches, and two thyristor auxiliary modules; each thyristor auxiliary module comprises two control switches; the two main switches comprise a main switch that is originally closed and a main switch that is to be closed; the main switches are connected to corresponding circuits of a voltage regulating coil via corresponding transformer taps;

[0043] Each transfer switch includes a plurality of static contacts, some of which are connected to corresponding transformer taps. One end of each of the two thyristor auxiliary modules is connected to a common output terminal, and the other end is connected to some of the static contacts of the corresponding transfer switch. The corresponding main switch, transfer switch, and control switch are controlled to open and close according to a preset timing sequence to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arcing during the opening and closing process of each switch.

[0044] As an implementation manner, the control switch is a rotary shaft switch.

[0045] As an embodiment, the transfer switch includes four static contacts, which switch between the following two states:

[0046] State 1: The first static contact and the third static contact are connected, and the second static contact and the fourth static contact are disconnected;

[0047] State 2: The first static contact and the third static contact are disconnected, and the second static contact and the fourth static contact are connected.

[0048] As an embodiment, the arc-free on-load tap changer terminal n is connected to the fourth static contact of the first transfer switch and the first static contact of the second transfer switch; the arc-free on-load tap changer terminal (n+1) is connected to the third static contact of the first transfer switch and the second static contact of the second transfer switch.

[0049] As an implementation mode, one end of a thyristor auxiliary module is connected to the first static contact and the second static contact of the first conversion switch, and the other end is connected to the common output terminal; one end of another thyristor auxiliary module is connected to the third static contact and the fourth static contact of the second conversion switch, and the other end is connected to the common output terminal.

[0050] As an implementation method, one control switch of a thyristor auxiliary module is always open and the other control switch is always closed; one control switch of another thyristor auxiliary module is always open and the other control switch is opened and closed according to the required working sequence.

[0051] As an implementation method, the two thyristor auxiliary modules have the same structure.

[0052] As an implementation method, each thyristor auxiliary module includes a pair of reverse-parallel thyristors; an RC series circuit is connected in parallel at both ends of the reverse-parallel thyristors; a capacitor, a resistor and a diode are connected in sequence between the gate and cathode of each thyristor; the positive pole of the diode is connected to the cathode of the corresponding thyristor, and the negative pole of the diode is connected to the gate of the corresponding thyristor; the gates of the two reverse-parallel thyristors are also connected in series with a control switch through a full-bridge rectifier circuit; two Zener diodes and a resistor are also connected in series between the gates of the two reverse-parallel thyristors and another control switch; wherein the two Zener diodes are connected in reverse series; after the Zener diode and the resistor are connected in series, they are connected to the output end of the full-bridge rectifier circuit, the negative pole of the Zener diode corresponds to the positive output end of the full-bridge rectifier circuit, and the positive pole of the Zener diode corresponds to the negative output end of the full-bridge rectifier circuit;.

[0053] A second aspect of the present invention provides a switching control method for an arc-free on-load tap changer.

[0054] In one or more embodiments, the present invention provides a first switching control method for an arc-free on-load tap changer, which includes:

[0055] Control the rotation of the rotating shaft to drive the moving contact to connect or disconnect with the corresponding static contact;

[0056] The corresponding main switches, transfer switches and control switches are controlled to open and close according to the preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arc during the opening and closing process of each switch.

[0057] As an embodiment, the rotation mode of the rotating shaft includes clockwise rotation and counterclockwise rotation.

[0058] As an implementation method, a switching process of a main switch includes:

[0059] The moving contact of the corresponding transfer switch contacts the corresponding static contact, closing the first control switch of the thyristor auxiliary module connected to the originally closed main switch and opening the originally closed main switch;

[0060] Closing the second control switch of the thyristor auxiliary module connected to the main switch to be closed, and opening the first control switch of the thyristor auxiliary module connected to the main switch that was originally closed;

[0061] After a set time interval, closing the first control switch of the thyristor auxiliary module connected to the main switch to be closed, thereby closing the main switch to be closed;

[0062] Disconnect all control switches, and the moving contacts of the corresponding transfer switches will be disconnected from the corresponding static contacts, completing the switching of the main switch.

[0063] As an implementation method, before the main switch is switched, the voltages across the two thyristor auxiliary modules are both zero.

[0064] The present invention provides a second switching control method for an arc-free on-load tap changer, which includes:

[0065] Linked and synchronously rotate to control the opening and closing of the corresponding main switches and transfer switches;

[0066] The corresponding main switches, transfer switches and control switches are controlled to open and close according to the preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arc during the opening and closing process of each switch.

[0067] The present invention provides a third switching control method for an arc-free on-load tap changer, which includes:

[0068] The originally closed main switch is opened, and a thyristor auxiliary module switches to the main switch to be closed;

[0069] The control switch of another thyristor auxiliary module is opened, and the thyristor auxiliary module is switched to the main switch to be closed, and after a preset time interval, the opened control switch of the thyristor auxiliary module is closed;

[0070] Close the main switch to complete the switching of the main switch.

[0071] As an implementation mode, before the main switch is switched, the two transfer switches are in different opening and closing states, and the corresponding control switches are closed according to the required working sequence control.

[0072] A third aspect of the present invention provides an electrical device.

[0073] In one or more embodiments, an electrical device includes:

[0074] a voltage regulating coil, which contains a number of transformer taps; and

[0075] an arc-free on-load tap-changer, wherein the arc-free on-load tap-changer is connected to the voltage regulating coil;

[0076] Wherein, the arc-free on-load tap changer is any of the arc-free on-load tap changers described above.

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] (1) The arc-free on-load tap changer provided by the present invention solves the problem that the existing arc-free on-load tap changer is not suitable for oil-immersed transformers by installing the moving contact on the rotating shaft. As the rotating shaft rotates, the moving contact is connected with the corresponding static contact. The arc-free on-load tap changer of the present invention uses the rotating shaft as the driving power, and finally controls the originally closed main switch, the transfer switch, the control switch and the main switch to be closed to match the opening and closing according to the preset timing, so as to achieve arc-free opening and closing process and switching between the main switches. Various switches and contacts can be operated in the oil tank of the oil-immersed transformer.

[0079] (2) The arc-free on-load tap-changer provided by the present invention can be implemented on the basis of the basic structure of the existing oil-immersed on-load tap-changer; the arc-free on-load tap-changer of the present invention can also be implemented on the basis of the basic structure of the existing oil-immersed de-excitation tap-changer.

[0080] (3) The present invention provides an arc-free on-load tap-changer, wherein the transfer switch includes a plurality of static contacts, the corresponding static contacts of the transfer switch are connected to the transformer tap, and at least one control switch is mounted on a rotating shaft, and the rotating shaft drives and controls the opening and closing. In this way, the oil-immersed vacuum on-load tap-changer can be upgraded on the basis of the basic structure of the existing oil-immersed vacuum on-load tap-changer, so that the opening and closing process is arc-free and switching between the main switches is achieved.

[0081] (4) The arc-free on-load tap changer of the present invention retains the experience accumulated in the past, simplifies the structure, reduces the volume, reduces the weight, reduces the cost, has low operating vibration, and has a low failure rate; and the time for a complete switching process is short.

[0082] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0084] Figure 1 is a circuit diagram of a thyristor auxiliary module according to an embodiment of the present invention;

[0085] Figure 2 This is a structural diagram of the rotating shaft of the first arc-free on-load tap changer according to an embodiment of the present invention;

[0086] Figure 3 This is a horizontal expansion structural diagram of the first arc-free on-load tap changer according to an embodiment of the present invention;

[0087] Figure 4 is a diagram showing the relationship between the radians of the static contacts according to an embodiment of the present invention;

[0088] Figure 5 This is a structural diagram of switches KB1 and KB2 according to an embodiment of the present invention;

[0089] Figure 6 1 is a structural diagram of a rotating shaft of a second arc-free on-load tap changer according to an embodiment of the present invention;

[0090] Figure 7 This is the timing diagram of n→(n+1) of the existing vacuum on-load tap-changer;

[0091] Figure 8 This is the timing diagram of the existing vacuum on-load tap-changer (n+1)→n;

[0092] Figure 9 is a timing diagram of n→(n+1) of the third arc-free on-load tap changer according to an embodiment of the present invention;

[0093] Figure 10 This is a timing diagram of (n+1)→n of the third arc-free on-load tap changer according to an embodiment of the present invention.

[0094] Among them, 1. tap I, 2. tap II, 3. tap III, 4. rotation axis, 5. fixed plate, 6. deflection axis, 7. lever arm, 8. spring arm, 9. first hoop, 10. second hoop, 11. switch KB1, 12. switch KB2. DETAILED DESCRIPTION

[0095] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0096] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0097] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0098] <Arc-free on-load tap-changer and switching control method>

[0099] To address the problems in the prior art that the existing arc-free on-load tap-changer is not suitable for use with oil-immersed transformers, and even if it is suitable for oil-immersed transformers, since various switches are distributed on two or three asynchronous rotating shafts, when one rotating shaft needs to rotate, another rotating shaft needs to be stationary, resulting in a complex operating structure; and there is a lack of a coordinated control mechanism for the rotating shafts, a matching scheme for the moving contacts and static contacts of the rotating shafts, and a drive scheme for controlling the switches, the present invention provides an arc-free on-load tap-changer and a corresponding switching control method.

[0100] Example 1

[0101] This embodiment provides an arc-free on-load tap changer, comprising at least two main switches, two transfer switches, and two thyristor auxiliary modules; each thyristor auxiliary module comprises two control switches; the two main switches comprise a previously closed main switch and a main switch to be closed; the main switches are connected to corresponding circuits of a voltage regulating coil via corresponding transformer taps; during the main switch switching process, the two thyristor auxiliary modules are connected in parallel with the previously closed main switch or the main switch to be closed according to the required timing;

[0102] The main switch and transfer switch are both rotary shaft switches, with their moving contacts arranged on the rotating shaft. The corresponding static contacts of the main switch and transfer switch are connected to the corresponding transformer taps. The moving contacts connect with the coaxial static contacts as the rotating shaft rotates. The corresponding main switches, transfer switches, and control switches are controlled to open and close according to a preset timing sequence to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arcing during the opening and closing process of each switch.

[0103] The arc-free on-load tap-changer of this embodiment uses a rotating shaft as a driving force and is suitable for oil-immersed transformers. The arc-free on-load tap-changer with contacts in a rotating sliding manner has a structure as shown below. Figure 2 As shown. Since the oil-immersed on-load tap-changer is generally a three-phase on-load tap-changer installed on the same insulated rotating shaft, the three-phase on-load tap-changer has the same structure and is driven synchronously by the rotating shaft. For the convenience of description, Figure 2 Take a single-phase oil-immersed on-load tap-changer with three taps as an example.

[0104] In this embodiment, the control switch is also a rotary shaft switch, and the moving contact of the control switch is also arranged on the rotating shaft.

[0105] All main switches and transfer switches have at least two sets of stationary contacts, each mounted on a corresponding track. These tracks are fixed and centered around the rotating shaft. The track is a circular insulating frame that does not move with the rotating shaft. The moving contacts are mounted on the rotating shaft and rotate with it.

[0106] Before the arc-free on-load tap changer is switched, one end of the thyristor auxiliary module is suspended or connected in parallel with the originally closed main switch. Before the arc-free on-load tap changer is switched, the voltage across both ends of the thyristor auxiliary module is zero.

[0107] During the arc-free on-load tap changer switching process, the thyristor auxiliary module is connected in parallel with the originally closed main switch or the main switch to be closed according to the required timing.

[0108] This embodiment is described by taking as an example that there are two static contact groups, that is, two tracks; each static contact group has three static contacts, and the number of movable contacts is three.

[0109] It is understood that, in other embodiments, those skilled in the art may specifically set the number of moving contacts and the number of static contact groups according to actual conditions.

[0110] In this embodiment, there are three stationary contacts on the first track, arranged in sequence. The arc length between the center positions of the first and second stationary contacts on the first track is equal to W, and the arc length between the center positions of the second and third stationary contacts on the first track is also equal to W. The second track also has stationary contacts, and the number of stationary contacts on the second track is equal to the number of stationary contacts on the first track. The center line of each stationary contact on the first track overlaps with the center line of a stationary contact on the second track. The stationary contacts on the first track with overlapping center lines are connected to the stationary contacts on the second track, and are sequentially connected to taps I, II, and III of the transformer coil L1.

[0111] The three static contacts on the first track have the same arc, which is equal to W1; the three static contacts on the second track have the same arc, which is equal to W2; the gaps between the static contacts on the second track have the same arc, and the arc of the gap ΔW = (W-W2). Figure 2 The rotating shaft structure diagram of the arc-free on-load tap-changer is expanded horizontally, as shown in Figure 3 and Figure 4 As shown. Requirement: 0 < ΔW <W1<0.5W<W2。

[0112] In this embodiment, there are three moving contacts on the rotating shaft: moving contact J3, moving contact Q1, and moving contact Q2; the moving contacts are installed on the rotating shaft and rotate with the rotating shaft; among them, moving contact Q1 and moving contact Q2 are respectively arranged on both sides of moving contact J3.

[0113] As the moving contact J3 rotates with the shaft, it connects or disconnects with the three static contacts on the first track in sequence, turning the main switch on and off. As the moving contacts Q1 and Q2 rotate with the shaft, they connect or disconnect with the three static contacts on the second track in sequence, turning the switch on and off. The center of the moving contact Q1 is on the second track to the left of the center of the moving contact J3, with an angle of 0.5W between them. The center of the moving contact Q2 is on the second track to the right of the center of the moving contact J3, with an angle of 0.5W between them.

[0114] The normal operating state of the arc-free on-load tap changer of this embodiment before switching is: the movable contact J3 on the rotating shaft is located on the center line of the stationary contact W1, and the movable contacts Q1 and Q2 are respectively located on the center lines of the gap.

[0115] In this embodiment, the thyristor auxiliary module M1 and the thyristor auxiliary module M2 have the same circuit, and the main circuit of each auxiliary circuit includes a pair of reverse-parallel thyristors; an RC series circuit is connected in parallel at both ends of the reverse-parallel thyristors; a capacitor, a resistor and a diode are connected between the gate and cathode of each thyristor; the positive electrode of the diode is connected to the cathode of the corresponding thyristor, and the negative electrode of the diode is connected to the gate of the corresponding thyristor; the gates of the two reverse-parallel thyristors are also connected in series with a control switch through a full-bridge rectifier circuit; two reverse-parallel-connected voltage regulators, a resistor and another control switch are also connected in series between the gates of the two reverse-parallel thyristors; the voltage regulator and the resistor are connected in series to the output end of the full-bridge rectifier circuit, the negative electrode of the voltage regulator corresponds to the positive output end of the full-bridge rectifier circuit, and the positive electrode of the voltage regulator corresponds to the negative output end of the full-bridge rectifier circuit.

[0116] Specifically, if Figure 1 As shown, the main circuit of each auxiliary circuit includes a pair of thyristors D1 and D2 connected in anti-parallel; a resistor R1 and a capacitor C1 are connected in series and then connected in parallel across the anti-parallel thyristors D1 and D2; the gates and cathodes of the two thyristors D1 and D2 are connected in parallel with capacitors C3 and C4, resistors R3 and R4, and diodes D3 and D4 respectively; the anodes of diodes D3 and D4 are connected to the cathodes of thyristors D1 and D2 respectively, and the cathodes of diodes D3 and D4 are connected to the gates of thyristors D1 and D2 respectively; Zener diodes D10 and D11 are connected in anti-parallel series and then connected in series with resistor R5, and then connected in series with a control switch KA, and then connected between the gates of the two thyristors D1 and D2. The input terminal of the full-bridge rectifier circuit, consisting of diodes D5, D6, D7, and D8, is connected in series with the control switch KB and then connected between the gates of the two thyristors D1 and D2. The voltage regulator D9 is connected in series with the resistor R6 and then connected to the output of the full-bridge rectifier circuit. The cathode of the voltage regulator D9 corresponds to the positive output terminal of the full-bridge rectifier circuit, and the anode of the voltage regulator D9 corresponds to the negative output terminal of the full-bridge rectifier circuit. The regulated voltage of the voltage regulator D9 is U1 = k1U2, where k1 is the reliability factor and should be between 1.2 and 2. U2 is the peak voltage of the regulating transformer's regulation interval. It is recommended that the regulated voltage of the voltage regulators D10 and D11 be 1 to 3 volts.

[0117] It should be noted that the specific working process of the thyristor auxiliary module has been disclosed in the patent document with application number CN201810290470.4 and will not be repeated here.

[0118] In this embodiment, the thyristor auxiliary module M1 is connected to the control switches KA1 and KB1 ; the thyristor auxiliary module M2 is connected to the control switches KA2 and KB2 .

[0119] The moving contact J3 is connected to the common terminal; the two ends of the main circuit of the thyristor auxiliary module M1 are connected to the moving contact Q1 and the common terminal, and the two ends of the main circuit of the thyristor auxiliary module M2 are connected to the moving contact Q2 and the common terminal.

[0120] In the specific implementation process, the control switches KA1 and KA2 are installed on the rotating shaft. When the control switches KA1 and KA2 rotate with the rotating shaft, they can respectively draw two concentric circular tracks, which are respectively called: the third track and the fourth track. There is a static contact W3 on the third track between the center line of the first static contact on the first track and the center line of the second static contact on the first track, and there is a static contact W4 on the fourth track. Similarly, there are repeated static contacts W3 and W4 on the third track and the fourth track between the center line of the second static contact on the first track and the center line of the third static contact on the first track, such as Figure 4 shown.

[0121] Control switch KA1 rotates with the shaft. When it encounters stationary contact W3, it closes. When it leaves stationary contact W3, it opens. Control switch KA2 rotates with the shaft. When it encounters stationary contact W4, it closes. When it leaves stationary contact W4, it opens. As can be seen, stationary contacts W3 and W4 do not need to be made of metal; they only need to trigger the closing of control switch KA1 or KA2.

[0122] When the rotating shaft rotates clockwise, the control switch KA1 must contact the static contact W3 before the moving contact J3 leaves the static contact W1; the control switch KA1 is allowed to leave the static contact W3 only after the moving contact J3 leaves the static contact W1; the control switch KA2 must contact the static contact W4 before the moving contact J3 contacts another static contact W1; the control switch KA2 is allowed to leave the static contact W4 only after the moving contact J3 contacts another static contact W1; and after the control switch KA1 leaves the static contact W3, the control switch KA2 is allowed to contact the static contact W4 only after at least the time interval t1 has passed.

[0123] When the rotating shaft rotates counterclockwise, the control switch KA2 must contact the static contact W4 before the moving contact J3 leaves the static contact W1; the control switch KA2 is allowed to leave the static contact W4 only after the moving contact J3 leaves the static contact W1; the control switch KA1 must contact the static contact W3 before the moving contact J3 contacts another static contact W1; the control switch KA1 is allowed to leave the static contact W3 only after the moving contact J3 contacts another static contact W1; and after the control switch KA2 leaves the static contact W4, the control switch KA1 is allowed to contact the static contact W3 only after at least the time interval t1 has passed.

[0124] In order to ensure that the time interval t1 is greater than the set time (for example: 0.015 seconds), the rotation axis should not rotate too fast. If the time for the rotation axis to rotate one circle is T seconds, then:

[0125] T>((0.015*2π) / (W2-W3–W4)).

[0126] Wherein: W2 is the radian of each static contact on the second track, W3 and W4 are the radians of each static contact on the third track and the fourth track respectively.

[0127] In this embodiment, the rotating shaft also has a control mechanism. When the rotating shaft rotates clockwise, before KA1 leaves the stationary contact W3, the control mechanism must open the control switch KB1 and close the control switch KB2. When the rotating shaft rotates counterclockwise, before KA2 leaves the stationary contact W3, the control mechanism must close the control switch KB1 and open the control switch KB2.

[0128] The switching control principle of the arc-free on-load tap changer of this embodiment is:

[0129] Control the rotation of the rotating shaft to drive the moving contact to connect or disconnect with the corresponding static contact;

[0130] The corresponding main switches, transfer switches and control switches are controlled to open and close according to the preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arc during the opening and closing process of each switch.

[0131] The rotation modes of the rotating shaft include clockwise rotation and counterclockwise rotation.

[0132] The switching process of the primary main switch in this embodiment includes:

[0133] The moving contacts of the two transfer switches come into contact with the static contacts, so that the two thyristor auxiliary modules are connected in parallel with the originally closed main switch or the main switch to be closed. The first control switch connected to the thyristor auxiliary module connected in parallel with the originally closed main switch is closed, thus opening the originally closed main switch.

[0134] Closing the second control switch connected to the thyristor auxiliary module in parallel with the main switch to be closed, and opening the first control switch connected to the thyristor auxiliary module in parallel with the main switch that was originally closed;

[0135] After a set time interval, closing a first control switch connected to the thyristor auxiliary module in parallel with the main switch to be closed, thereby closing the main switch to be closed;

[0136] Disconnect all control switches, and the moving contacts of the two transfer switches will be disconnected from the static contacts, completing the switching of the main switch.

[0137] Combine Figure 2 , the switching process of the primary main switch in this embodiment is:

[0138] (1) The moving contacts Q1 and Q2 make contact with the two stationary contacts W2 respectively; the control switch KA of the thyristor auxiliary module connected in parallel with the originally closed main switch is closed;

[0139] (2) Open the main switch that was originally closed;

[0140] (3) Close the control switch KB of another thyristor auxiliary module connected in parallel with the main switch to be closed;

[0141] (4) disconnecting the control switch KA of the thyristor auxiliary module connected in parallel with the originally closed main switch;

[0142] (5) After a time interval t1 (wherein the time interval t1 is greater than 0.015 seconds), closing the control switch KA of the thyristor auxiliary circuit in parallel with the main switch to be closed;

[0143] (6) Close the main switch to be closed;

[0144] (7) Disconnect all control switches of the thyristor auxiliary module;

[0145] (8) The moving contacts Q1 and Q2 are out of contact with the stationary contact W2;

[0146] (9) Complete the switching of the main switch.

[0147] The following combination Figure 2 , the switching process of the primary main switch of this embodiment is explained with the rotation axis rotating clockwise and counterclockwise respectively:

[0148] The switching control process of the arc-free on-load tap changer in this embodiment when rotating clockwise is as follows:

[0149] (1) The moving contact J3 rotates clockwise from the centerline of the static contact W1 that it has already contacted. The moving contact Q1 contacts the static contact W2 that is connected to the static contact W1 that the moving contact J3 has already contacted. The moving contact Q2 contacts the static contact W2 that is connected to the static contact W1 that the moving contact J3 will soon contact. The control switch KA1 of the thyristor auxiliary module M1 contacts W3, and the control switch KA1 is closed. The load current flow path remains unchanged and continues to flow from the static contact W1 that the moving contact J3 has already contacted through the moving contact J3 to the common terminal.

[0150] (2) The moving contact J3 is disconnected from the static contact W1 that was originally in contact with it; the load current flows from the static contact W2 that was originally connected to the static contact W1, through the moving contact Q1, and the thyristor auxiliary module M1, into the common terminal;

[0151] (3) The control switch KB2 of the thyristor auxiliary module M2 is closed; the load current flow path remains unchanged;

[0152] (4) The control switch KA1 of the thyristor auxiliary module M1 is disconnected from W3, and the control switch KA1 is turned off; each zero crossing of the load current triggers the thyristor auxiliary module M2 once, causing the load current to flow from the static contact W2 connected to the static contact W1 to be touched, through the moving contact Q2, and the thyristor auxiliary module M2 to the common terminal;

[0153] (5) After time interval t1, the control switch KA2 of the thyristor auxiliary module M2 contacts W4, and the control switch KA2 is closed; the load current flow path remains unchanged;

[0154] (6) The moving contact J3 contacts the stationary contact W1 to be contacted; the load current flows from the stationary contact W1 contacted by the moving contact J3 to the common terminal through the moving contact J3;

[0155] (7) The moving contacts Q1 and Q2 are disconnected from the static contact W2; the control switch KA2 of the thyristor auxiliary module M2 is disconnected from W4, and the control switch KA2 is disconnected; the control switch KB2 of the thyristor auxiliary module M2 is disconnected;

[0156] (8) The moving contact J3 rotates to the centerline of the newly contacted stationary contact W1 and stops rotating, completing one switching of the main switch. The time interval t1 is greater than 0.015 seconds.

[0157] The switching control process of the arc-free on-load tap-changer in this embodiment when rotating counterclockwise is as follows:

[0158] (1) The moving contact J3 rotates counterclockwise from the centerline position of the static contact W1 that has already been in contact with it. The moving contact Q2 contacts the static contact W2 that is connected to the static contact W1 that the moving contact J3 has already contacted. The moving contact Q1 contacts the static contact W2 that is connected to the static contact W1 that the moving contact J3 will soon contact. The control switch KA2 of the thyristor auxiliary module M2 contacts W4, and the control switch KA2 is closed. The load current flow path remains unchanged and continues to flow from the static contact W1 that the moving contact J3 has already contacted through the moving contact J3 to the common terminal.

[0159] (2) The moving contact J3 is disconnected from the static contact W1 that was originally in contact with it; the load current flows from the static contact W2 that was originally connected to the static contact W1, through the moving contact Q2, and the thyristor auxiliary module M2, to the common terminal;

[0160] (3) The control switch KB2 of the thyristor auxiliary module M1 is closed; the load current flow path remains unchanged;

[0161] (4) The control switch KA2 of the thyristor auxiliary module M2 is disconnected from W4, and the control switch KA2 is turned off; each zero crossing of the load current triggers the thyristor auxiliary module M1 once, causing the load current to flow from the static contact W2 connected to the static contact W1 to be touched, through the moving contact Q1, and the thyristor auxiliary module M1 to the common terminal;

[0162] (5) After time interval t1, the control switch KA1 of the thyristor auxiliary module M1 contacts W3, and the control switch KA1 is closed; the load current flow path remains unchanged;

[0163] (6) The moving contact J3 contacts the stationary contact W1 to be contacted; the load current flows from the stationary contact W1 contacted by the moving contact J3 to the common terminal through the moving contact J3;

[0164] (7) The moving contacts Q1 and Q2 are disconnected from the static contact W2; the control switch KA1 of the thyristor auxiliary module M1 is disconnected from W3, and the control switch KA1 is disconnected; the control switch KB1 of the thyristor auxiliary module M1 is disconnected;

[0165] (8) The moving contact J3 rotates to the center line position of the newly contacted static contact W1 and stops rotating; the switching of the main switch is completed.

[0166] The arc-free on-load tap changer of this embodiment, like existing oil-immersed on-load tap changers, uses a rotating shaft as its driving force, allowing it to operate various switches and contacts within the oil tank of an oil-immersed transformer. Thus, the arc-free on-load tap changer of the present invention can be retrofitted onto the basic structure of existing oil-immersed on-load tap changers.

[0167] Existing oil-immersed on-load tapchangers are driven by AC motors. To prevent power outages and interruptions during the switching process, existing on-load tapchangers have spring release mechanisms. If power is lost during the switching process, the spring release mechanism ensures a complete switching process. However, the springs take a long time to charge, and they only charge after receiving a switching command. This makes a complete switching process in existing on-load tapchangers quite lengthy. The spring energy storage and release mechanisms of these on-load tapchangers are complex, resulting in significant vibration during operation and a high failure rate.

[0168] The arc-free on-load tap-changer of this embodiment can be driven by a DC motor and electrically stored. The arc-free on-load tap-changer can eliminate the spring energy storage mechanism and the spring energy release mechanism.

[0169] It should be noted that the drive motor of the oil-immersed on-load tap changer of this embodiment can be a DC motor. The AC power originally used to power the AC motor is then fed through a bridge rectifier circuit and a voltage regulator circuit to the DC motor. A capacitor energy storage circuit is connected in parallel to the output of the bridge rectifier circuit. The stored energy in the capacitor energy storage circuit is sufficient to provide at least one complete operation of the on-load tap changer. This electrical energy storage can occur before receiving a switching command, resulting in a shorter switching time for the arc-free on-load tap changer of this embodiment. Consequently, the spring energy storage and release mechanisms of the arc-free on-load tap changer of this embodiment can be eliminated.

[0170] The arc-free on-load tap changer of this embodiment eliminates the transition resistor, eliminating the need for heat generation during the switching process. This eliminates the need for a fast switching mechanism (to ensure the transition resistor remains energized for no more than 40 milliseconds) required in existing on-load tap changers. The arc-free on-load tap changer of this embodiment can complete the switching process in tens of seconds. Therefore, the arc-free on-load tap changer of the present invention can be modified based on the basic structure of existing oil-immersed off-circuit tap changers.

[0171] The arc-free on-load tap changer of this embodiment has a simple structure, small operating vibration and low failure rate. Figure 2 The arc-free on-load tap-changer with this structure is a composite arc-free on-load tap-changer. The composite arc-free on-load tap-changer combines the selector and the switch into one, simplifying the on-load tap-changer structure and reducing the cost. However, it can only be used in situations where the selector is relatively simple. If the selector of the on-load tap-changer is relatively complex and is not suitable for composite on-load tap-changer, a combined structure with the selector and switch connected in series can be used. Figure 2 The structure has two static contacts on the first track, which is actually a switch structure. If this switch is connected in series with the existing selector, a combined arc-free on-load tap changer can be formed.

[0172] Example 2

[0173] This embodiment provides an arc-free on-load tap changer, the structure of which is the same as that of the first embodiment, except that this embodiment uses a mechanical linkage mechanism to control the control switches KB1 and KB2.

[0174] like Figure 5 As shown, this embodiment includes a deflection shaft 6, which is fixed on the rotating shaft 4 and rotates with the rotating shaft 4. The deflection shaft 6 is equipped with a lever arm 7 and a spring arm 8 that can rotate around the deflection shaft 6. One end of the spring arm 8 has a contact. The contact contacts or disengages with the corresponding control switch as the rotating shaft rotates 4, causing the corresponding control switch to open or close.

[0175] The working process of the mechanical linkage mechanism of this embodiment is as follows:

[0176] The rotating shaft 4 drives the fixed plate 5 to rotate. The fixed plate 5 also has a deflection shaft 6 mounted on it. The deflection shaft is equipped with a lever arm 7 and a spring arm 8. The lever arm 7 and spring arm 8 can rotate about the deflection shaft 6. One end of the spring arm 8 has a contact. A circular hoop is mounted on the stationary insulating frame, centered on the rotating shaft 4. A gap exists on the centerline of the stationary contact W1, dividing the hoop into several segments. For each stationary contact W1, there are multiple hoop gaps. For example, three stationary contacts W1 have three hoop gaps, which divide the hoop into a first hoop 9 and a second hoop 10. The first normal operating state of the arc-free on-load tap changer before switching is when the lever arm 7 is located on the centerline of the hoop gap.

[0177] When the rotating shaft 4 rotates clockwise, the lever arm 7 encounters the second hoop 10, which pushes the lever arm 7 counterclockwise around the deflection axis 6. The lever arm 7 then drives the spring arm 8 counterclockwise, causing the contacts of the spring arm 8 to contact the contacts of the switch KB2, closing the switch KB2. This continues until the lever arm 7 disengages from the second hoop 10 and encounters another hoop gap. The lever arm 7 then returns to the centerline of the hoop gap. The spring arm 8 also returns to the centerline of the hoop gap, and the contacts of the spring arm 8 disengage from the contacts of the switch KB2, opening the switch KB2.

[0178] When the rotating shaft 4 rotates counterclockwise, the lever arm 7 encounters the first hoop 9, which pushes the lever arm 7 clockwise around the deflection axis 6. The lever arm 7 then drives the spring arm 8 clockwise, causing the contacts of the spring arm 8 to contact the contacts of the switch KB1, closing the switch KB1. This continues until the lever arm 7 disengages from the first hoop 9 and encounters another hoop gap. The lever arm 7 then returns to the centerline of the hoop gap. The spring arm 8 also returns to the centerline of the hoop gap, and the contacts of the spring arm 8 disengage from the contacts of the switch KB1, opening the switch KB1.

[0179] It is understandable that those skilled in the art can design the structure of the mechanical linkage mechanism according to actual conditions, which will not be described in detail here.

[0180] It should be noted that the switching control process of the arc-free on-load tap changer of this embodiment is the same as the switching control process of the arc-free on-load tap changer of the first embodiment, and will not be repeated here.

[0181] Example 3

[0182] This embodiment provides an arc-free on-load tap changer, the structure of which is the same as that of the first embodiment, except that the control mechanism for controlling the control switches KB1 and KB2 in this embodiment is implemented by a transfer switch driven by a rotating shaft.

[0183] In the book "Electrical Mechanism of On-Load Tap Changers" edited by Zhu Yinghao et al., China Electric Power Press, 2012, pages 63-66, the transfer switch MTF driven by a rotating shaft can constitute the control switches KB1 and KB2. The four static contacts of the transfer switch MTF in the book are MTF1, MTF2, MTF3, and MTF4; the transfer switch can switch between two states: (1) the first contact and the third contact are connected, and the second contact and the fourth contact are disconnected; (2) the first contact and the third contact are disconnected, and the second contact and the fourth contact are connected. Contacts MTF1 and MTF3 can serve as the two ends of the control switch KB1, and contacts MTF2 and MTF4 can serve as the two ends of the control switch KB2.

[0184] It's important to note that the transfer switch MTF described in "Electrical Mechanism of On-Load Tap Changers" is a high-current switch, while the control switches KB1 and KB2 are low-current switches. Therefore, based on the operating principle of the transfer switch MTF, it's necessary to reduce its size and implement the functions of the control switches KB1 and KB2. A detailed analysis will be omitted.

[0185] It should be noted that the switching control process of the arc-free on-load tap changer of this embodiment is the same as the switching control process of the arc-free on-load tap changer of the first embodiment, and will not be repeated here.

[0186] Example 4

[0187] Figure 2 In the example of an arc-free on-load tap-changer, the curvature of the static contact is larger, while the curvature of the moving contact is smaller. It can be seen that the size of the contact curvature is used to control the duration of contact between the static and moving contacts and the order in which they make contact.

[0188] The difference between this embodiment and the first embodiment is that the curvature of the static contact is reduced and the curvature of the moving contact is increased. Figure 6 shown.

[0189] The rotating shaft structure of the arc-free on-load tap changer in this embodiment is as follows: Figure 6 As shown. In this embodiment, there are three stationary contacts on the first track, arranged in sequence. The arc length between the center positions of the first and second stationary contacts on the first track is equal to W, and the arc length between the center positions of the second and third stationary contacts on the first track is also equal to W. The second track also has stationary contacts, and the number of stationary contacts on the second track is equal to the number of stationary contacts on the first track. The center line of each stationary contact on the first track overlaps with the center line of a stationary contact on the second track. The stationary contacts on the first track with overlapping center lines are connected to the stationary contacts on the second track and are connected in sequence to the three taps of the transformer coil L1.

[0190] In this embodiment, the rotating shaft has at least three moving contacts: moving contact J3, moving contact Q1, and moving contact Q2. The moving contact is mounted on the rotating shaft and rotates with the rotating shaft. When the moving contact J3 rotates with the rotating shaft, it sequentially connects with the three stationary contacts on the first track. When the moving contacts Q1 and Q2 rotate with the rotating shaft, they sequentially connect with the three stationary contacts on the second track. The center of the moving contact Q1 is on the second track to the left of the center of the moving contact J3, with an angle of 0.5W between the two. The center of the moving contact Q2 is on the second track to the right of the center of the moving contact J3, with an angle of 0.5W between the two.

[0191] The contact of the moving contact J3 has an arc W 1动 , the moving contact Q1 and the moving contact Q2 have an arc W 2动 , the arc of the gap ΔW between the moving contact Q1 and the moving contact Q2 动 =(WW 2动 ). Requirement: 0 < ΔW 动 <W 1动 <0.5W <W 2动 ;like Figure 6 Wherein: W is the arc between the center positions of the static contacts on the first track.

[0192] It should also be noted that the opening and closing of the control switch in this embodiment is controlled by a control mechanism. The control mechanism can be implemented using the second or third embodiment or other existing control mechanisms. Those skilled in the art can select the specific control mechanism according to actual conditions, and will not be described here.

[0193] The switching control method of the arc-free on-load tap changer of this embodiment is the same as that of the arc-free on-load tap changer of the first embodiment, and is not repeated here.

[0194] pass Figure 2 and Figure 6 In comparison, the arc-free on-load tap changer of this embodiment has a relatively small curvature of each static contact of the first and second rails, while the curvature of the moving contact is relatively large. Since there are only three moving contacts and the number of static contacts may be large, the manufacturing cost of the arc-free on-load tap changer of this embodiment is lower than that of the arc-free on-load tap changer of the first embodiment.

[0195] Example 5

[0196] This embodiment provides an arc-free on-load tap changer, comprising at least two main switches, two transfer switches, and two thyristor auxiliary modules; each thyristor auxiliary module comprises two control switches; the two main switches comprise a previously closed main switch and a main switch to be closed; the main switches are connected to corresponding circuits of a voltage regulating coil via corresponding transformer taps; during the main switch switching process, the two thyristor auxiliary modules are connected in parallel with the previously closed main switch or the main switch to be closed according to the required timing;

[0197] The main switch and transfer switch are both rotary shaft switches, in which the main switch and the corresponding transfer switch are linked and rotate synchronously; the corresponding main switch, transfer switch and control switch are controlled to open and close according to a preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arc during the opening and closing process of each switch.

[0198] It should be noted here that the control mechanism is a mechanical linkage mechanism, and its structure can adopt the specific structure of the mechanical linkage mechanism described in Example 2, or it can adopt the control mechanism described in Example 3. Those skilled in the art can make specific settings according to actual conditions, and will not be repeated here.

[0199] In this embodiment, the two thyristor auxiliary modules have the same structure, and their specific structures are as follows: Figure 1 As shown, the specific description is the same as that of embodiment 1 and will not be repeated here.

[0200] The switching control method of the arc-free on-load tap changer of this embodiment includes:

[0201] Linked and synchronously rotate to control the opening and closing of the corresponding main switches and transfer switches;

[0202] The corresponding main switches, transfer switches and control switches are controlled to open and close according to the preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arc during the opening and closing process of each switch.

[0203] Example 6

[0204] This embodiment provides an arc-free on-load tap changer, comprising at least two main switches, two transfer switches, and two thyristor auxiliary modules; each thyristor auxiliary module comprises two control switches; the two main switches comprise a main switch that is originally closed and a main switch that is about to be closed; the main switches are connected to corresponding circuits of a voltage regulating coil via corresponding transformer taps;

[0205] Each transfer switch includes a plurality of static contacts, some of which are connected to corresponding transformer taps. One end of each of the two thyristor auxiliary modules is connected to a common output terminal, and the other end is connected to some of the static contacts of the corresponding transfer switch. The corresponding main switch, transfer switch, and control switch are controlled to open and close according to a preset timing sequence to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arcing during the opening and closing process of each switch.

[0206] Due to the numerous advantages of oil-immersed vacuum on-load tap-changers, existing oil-immersed vacuum on-load tap-changers are being gradually upgraded to oil-immersed vacuum on-load tap-changers. Oil-immersed vacuum on-load tap-changers generally employ a combination type, where the on-load tap-changer selector selects the originally closed main switch and the main switch to be closed (one is an odd-numbered main switch, the other is an even-numbered main switch), and then a switcher switches between the two selected switches. Analysis of the selector is common knowledge and will not be elaborated upon here. This embodiment builds upon the basic structure of an existing oil-immersed vacuum on-load tap-changer to achieve an arc-free on-load tap-changer. Essentially, it is a modified oil-immersed vacuum on-load tap-changer with a switcher.

[0207] There is an existing vacuum on-load tap-changer driven by a rotary shaft, suitable for oil-immersed transformers, such as Figure 7 The process of switching tap n to (n+1) is as shown in Figure 7 The process of switching tap (n+1) to tap n is shown as Figure 8 For a detailed introduction to existing vacuum on-load tap-changers, please refer to Zhu Yinghao and Shen Dazhong, Electrical Mechanism of On-Load Tap-Changers, China Electric Power Press, 2012, p63-66.

[0208] In this embodiment, the arc-free on-load tap changer includes at least two main switches, two transfer switches, and two thyristor auxiliary modules. The transfer switches include four static contacts that switch between the following two states:

[0209] State 1: The first static contact and the third static contact are connected, and the second static contact and the fourth static contact are disconnected;

[0210] State 2: The first static contact and the third static contact are disconnected, and the second static contact and the fourth static contact are connected.

[0211] For example:

[0212] The four static contacts of the transfer switch TTF are TTF1, TTF2, TTF3, and TTF4, and the four static contacts of the transfer switch MTF are MTF1, MTF2, MTF3, and MTF4;

[0213] The transfer switch can switch between two states: (1) the first contact and the third contact are connected, and the second contact and the fourth contact are disconnected; (2) the first contact and the third contact are disconnected, and the second contact and the fourth contact are connected.

[0214] The main switch MCA is connected between the arc-free on-load tapchanger terminal n and terminal Y, the main switch MCB is connected between the arc-free on-load tapchanger terminal (n+1) and terminal Y, the arc-free on-load tapchanger terminal n is further connected to terminal TTF4 and terminal MTF1, the arc-free on-load tapchanger terminal (n+1) is further connected to terminal TTF3 and terminal MTF2, one end of the thyristor auxiliary module M1 is connected to terminal MTF3 and terminal MTF4, and the other end of the thyristor auxiliary module M1 is connected to terminal Y; one end of the thyristor auxiliary module M2 is connected to terminal TTF1 and terminal TTF2, and the other end of the thyristor auxiliary module M2 is connected to terminal Y; terminal Y is a common output terminal.

[0215] The structure of the two thyristor auxiliary modules in this embodiment is as follows: Figure 1 As shown. Thyristor auxiliary module M1 includes control switches KA1 and KB1; thyristor auxiliary module M2 includes control switches KA2 and KB2. Control switch KA1 of thyristor auxiliary module M1 is always off, while control switch KB1 is always closed. Control switch KB2 is always off. Control switch KA2 is a rotary shaft switch, mounted on a rotating shaft and driven to open and close by the shaft. The opening and closing sequence of control switch KA2 is determined based on requirements.

[0216] In this embodiment, the control switch KA2 can be used Figure 7 and Figure 8 The control switch KA2 is designed to open and close according to the operating sequence of the vacuum switch TTV. The control switch KA2 can be modified based on the drive structure of the vacuum switch TTV. Since the vacuum switch TTV is a high-current switch and the control switch KA2 is a low-current switch, the size of the control switch KA2 needs to be reduced based on the drive method of the vacuum switch TTV to achieve the function of the control switch KA2.

[0217] pass Figure 7 and Figure 9 By comparison, it can be seen that the arc-free on-load tap-changer of this embodiment eliminates the vacuum switch MSV, vacuum switch TTV, and transition resistor R that are originally part of the vacuum on-load tap-changer. Instead, the main circuit terminals of the thyristor auxiliary module M1 are connected to the terminals of the original vacuum switch MSV, while the main circuit terminals of the thyristor auxiliary module M2 are connected to the terminals of the original series circuit of the vacuum switch TTV and transition resistor R. Because the thyristor auxiliary module is smaller than the vacuum switch MSV and TTV, the thyristor auxiliary module M1 and the thyristor auxiliary module M2 can be installed in the place of the vacuum switch MSV and TTV, respectively, thus reducing their size.

[0218] The opening and closing of each switch of the arc-free on-load tap-changer of this embodiment can adopt the same or similar timing as that of the vacuum on-load tap-changer.

[0219] The normal operating state of each switch of the arc-free on-load tap changer of this embodiment before switching is:

[0220] When the main switch MCA is closed and the main switch MCB is open, the transfer switch contacts TTF1 and TTF3 are closed, the transfer switch contacts MTF2 and MTF4 are closed, and the control switch KA2 is closed. Alternatively, when the main switch MCB is closed, the main switch MCA is open, the transfer switch contacts TTF2 and TTF4 are closed, the transfer switch contacts MTF1 and MTF3 are closed, and the control switch KA2 is closed.

[0221] The process of switching the tap n of the arc-free on-load tap changer to (n+1) in this embodiment can be achieved by Figure 7 Working sequence. Figure 7 If the third and fifth steps in the working sequence are removed, the third type of arc-free on-load tap-changer will be easier to operate; Figure 7 In the working sequence, the operation of the transfer switch TTV in step 9 is moved forward to step 7 and completed, and step 9 is cancelled. Then the third type of arc-free on-load tap-changer has better performance. Figure 9 shown.

[0222] The process of switching the tap (n+1) of the arc-free on-load tap changer to tap n in this embodiment can be achieved by Figure 8 Working sequence. Figure 8 If the third and fifth steps in the working sequence are removed, the third type of arc-free on-load tap-changer will be easier to operate; Figure 8 In the working sequence, the operation of the transfer switch TTV in step 9 is moved forward to step 7 and completed, and step 9 is cancelled. Then the third type of arc-free on-load tap-changer has better performance. Figure 10 shown.

[0223] The switching control principle of the arc-free on-load tap changer of this embodiment is:

[0224] The originally closed main switch is opened, and a thyristor auxiliary module switches to the main switch to be closed;

[0225] The control switch of another thyristor auxiliary module is opened, and the thyristor auxiliary module is switched to the main switch to be closed, and after a preset time interval, the opened control switch of the thyristor auxiliary module is closed;

[0226] Close the main switch to complete the switching of the main switch.

[0227] Specifically, the switching control process of the arc-free on-load tap changer of this embodiment is as follows:

[0228] (1) Disconnect the main switch that was originally closed;

[0229] (2) The thyristor auxiliary module M1 switches to the main switch to be closed;

[0230] (3) The control switch KA2 of the thyristor auxiliary module M2 is disconnected;

[0231] (4) The thyristor auxiliary module M2 switches to the main switch to be closed;

[0232] (5) After time interval t1, the control switch KA2 of the thyristor auxiliary module M2 is closed;

[0233] (6) Close the main switch to be closed;

[0234] (7) Complete the switching of the main switch.

[0235] The time interval t1 is greater than a preset time (eg, 0.015 seconds).

[0236] The arc-free on-load tap-changer of this embodiment retains most of the structure of the existing oil-immersed vacuum on-load tap-changer, which not only retains the accumulated experience in the past, but also simplifies the structure and reduces the volume.

[0237] It should be noted here that the parts common to the arc-free on-load tap-changer of the present embodiment and the arc-free on-load tap-changer of the first embodiment are not repeated here.

[0238] <Electrical Equipment>

[0239] In one or more embodiments, an electrical device is provided, comprising:

[0240] a voltage regulating coil, which contains a number of transformer taps; and

[0241] an arc-free on-load tap-changer, wherein the arc-free on-load tap-changer is connected to the voltage regulating coil;

[0242] The arc-free on-load tap changer is the arc-free on-load tap changer described in any one of the above-mentioned embodiments 1 to 6.

[0243] The transformer in this embodiment is an oil-immersed transformer or a transformer with an oil-immersed vacuum on-load tap-changer.

[0244] The electrical device can be constructed in any desired method and manner as required, for example as a compensation choke for influencing reactive power in an AC power grid or as a local grid transformer or a power transformer or a variable transformer or a phase-shifting transformer or a rectifier transformer or a reactive power compensation device; and / or so that the device includes at least one or no additional regulating winding and / or at least one or no additional arc-free on-load tap changer and / or at least one mains winding.

[0245] For example, one of the proposed methods can be carried out with each of the proposed on-load tap changers and each of the proposed devices.

[0246] Preferably, each of the proposed arc-free on-load tap changers can be designed and / or used and / or suitable such that each of the proposed arc-free on-load tap changers carries out and / or can carry out one of the proposed methods. Preferably, each of the proposed devices can be designed and / or used and / or suitable such that each of the proposed devices carries out and / or can carry out one of the proposed methods.

[0247] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An arc-free on-load tap changer, characterized in that: The system comprises at least two main switches, two transfer switches, and two thyristor auxiliary modules; each thyristor auxiliary module comprises two control switches; the two main switches comprise one originally closed main switch and one to be closed; the main switches are connected to corresponding circuits of the voltage regulating coil via corresponding transformer taps; during the switching process of the main switches, the two thyristor auxiliary modules are connected in parallel with the originally closed main switch or the to-be-closed main switch according to the required timing; The main switch and transfer switch are both rotary switches, with their moving contacts disposed on the same rotating shaft. The corresponding static contacts of the main switch and transfer switch are connected to corresponding transformer taps, with the moving contacts connecting with the coaxial static contacts as the rotating shaft rotates. The main switch, transfer switch, and control switch are controlled to open and close according to a preset timing sequence, ensuring uninterrupted transfer of load current from the originally closed main switch to the upcoming main switch, and arcing-free during the opening and closing of each switch. The static contacts of all main switches and transfer switches are divided into at least two groups, and each group of static contacts is mounted on a corresponding track, and the tracks are all fixed with the rotation axis as the center; There are at least three moving contacts on the rotating shaft, including moving contact J3, moving contact Q1, and moving contact Q2; the moving contact is installed on the rotating shaft and rotates with the rotating shaft; among them, moving contact Q1 and moving contact Q2 are respectively arranged on both sides of moving contact J3; when moving contact J3 rotates with the rotating shaft, they are connected or disconnected with the static contact on the first track in turn, realizing the connection and disconnection of the main switch; when moving contact Q1 and moving contact Q2 rotate with the rotating shaft, they are connected or disconnected with the static contact on the second track in turn, realizing the switching of the transfer switch; the center position of moving contact Q1 is on the second track to the left of the center of moving contact J3, and the arc between the two is 0.5 W The center of the moving contact Q2 is on the second track to the right of the center of the moving contact J3, and the arc between the two is 0.5 W ,in, W It is the arc between the center positions of each static contact on the first track.

2. The arc-free on-load tap changer according to claim 1, characterized in that: One end of each of the two thyristor auxiliary modules is suspended or connected in parallel with the originally closed main switch before the main switch is switched, and the voltages at both ends of the two thyristor auxiliary modules are zero.

3. The arc-free on-load tap changer according to claim 1, characterized in that: The control switch is also a rotary shaft switch, and the moving contact of the control switch is also arranged on the rotating shaft.

4. The arc-free on-load tap changer according to claim 1, characterized in that: The number of stationary contacts in each group of stationary contacts is the same.

5. The arc-free on-load tap changer according to claim 1, characterized in that: Each set of static contacts is installed on the corresponding track with equal arc.

6. The arc-free on-load tap changer according to claim 1, characterized in that: When the static contacts of all main switches and transfer switches are divided into two groups, the relationship between the arcs of the static contacts on the two tracks is: 0<Δ W < W 1<0.5 W < W 2; D W= ( WW 2); in: W and W 1 is the arc between the center positions of each static contact on the first track and the arc of each static contact, W 2 and Δ W are the radians of each static contact on the second track and the radian of the static contact gap.

7. The arc-free on-load tap changer according to claim 1, characterized in that: Before the main switch is switched, the normal operating state of the arc-free on-load tap-changer is: A moving contact on the rotating shaft is located on the center line of a static contact, and the other moving contacts are respectively located on the center lines of the gaps between the static contacts.

8. The arc-free on-load tap changer according to claim 7, characterized in that: When there are three moving contacts on the rotating shaft, the first moving contact and the second moving contact are arranged on both sides of the third moving contact. The relationship between the arcs of the three moving contacts is: 0<Δ W 动 < W 1动 <0.5 W < W 2动 ; D W 动 = ( WW 2动 ); in: W is the arc between the center positions of the static contacts on the first track, W 1动 is the arc of the third moving contact, W 2动 is the arc of the first moving contact and the second moving contact respectively, Δ W 动 is the radian of the gap between the first moving contact and the second moving contact.

9. The arc-free on-load tap changer according to claim 8, characterized in that: The arc of the static contact is greater than that of the moving contact.

10. The arc-free on-load tap changer according to claim 8, characterized in that: The arc of the static contact is less than or equal to the arc of the moving contact.

11. The arc-free on-load tap changer according to claim 1, characterized in that: The opening and closing of the control switch is controlled by a control mechanism.

12. The arc-free on-load tap changer according to claim 11, characterized in that: The control mechanism is a mechanical linkage mechanism.

13. The arc-free on-load tap changer according to claim 12, characterized in that: The mechanical linkage mechanism includes a deflection shaft, which is fixed on the rotating shaft and rotates with the rotating shaft. A lever arm and a spring arm that can rotate around the deflection shaft are installed on the deflection shaft. A contact is provided at one end of the spring arm. The contact contacts or disengages with the corresponding control switch as the rotating shaft rotates, causing the corresponding control switch to open and close.

14. The arc-free on-load tap changer according to claim 11, characterized in that: The control mechanism is realized by a transfer switch driven by a rotating shaft.

15. The arc-free on-load tap changer according to claim 1, characterized in that: The two thyristor auxiliary modules have the same structure.

16. The arc-free on-load tap changer according to claim 15, characterized in that: Each thyristor auxiliary module includes a pair of anti-parallel thyristors; an RC series circuit is connected in parallel at both ends of the anti-parallel thyristors; a capacitor, a resistor and a diode are connected in sequence between the gate and cathode of each thyristor; the positive electrode of the diode is connected to the cathode of the corresponding thyristor, and the negative electrode of the diode is connected to the gate of the corresponding thyristor; the gates of the two anti-parallel thyristors are also connected in series with a control switch through a full-bridge rectifier circuit; two Zener diodes and a resistor are also connected in series between the gates of the two anti-parallel thyristors and another control switch; wherein the two Zener diodes are connected in anti-parallel series; after the Zener diode and the resistor are connected in series, they are connected to the output end of the full-bridge rectifier circuit, the negative electrode of the Zener diode corresponds to the positive output end of the full-bridge rectifier circuit, and the positive electrode of the Zener diode corresponds to the negative output end of the full-bridge rectifier circuit.

17. A switching control method for an arc-free on-load tap changer, characterized in that: The arc-free on-load tap changer is the arc-free on-load tap changer according to any one of claims 1 to 16, and the switching control method includes: Control the rotation of the rotating shaft to drive the moving contact to connect or disconnect with the corresponding static contact; The corresponding main switches, transfer switches and control switches are controlled to open and close according to the preset timing to achieve uninterrupted transfer of load current from the originally closed main switch to the main switch to be closed, and there is no arc during the opening and closing process of each switch.

18. The switching control method of the arc-free on-load tap changer according to claim 17, characterized in that: The rotation modes of the rotating shaft include clockwise rotation and counterclockwise rotation.

19. The switching control method of the arc-free on-load tap changer according to claim 17, characterized in that: The switching process of a main switch includes: The moving contact of the corresponding transfer switch contacts the corresponding static contact, closing the first control switch of the thyristor auxiliary module connected to the originally closed main switch and opening the originally closed main switch; Closing the second control switch of the thyristor auxiliary module connected to the main switch to be closed, and opening the first control switch of the thyristor auxiliary module connected to the main switch that was originally closed; After a set time interval, closing the first control switch of the thyristor auxiliary module connected to the main switch to be closed, thereby closing the main switch to be closed; Disconnect all control switches, and the moving contacts of the corresponding transfer switches will be disconnected from the corresponding static contacts, completing the switching of the main switch.

20. The switching control method of the arc-free on-load tap changer according to claim 17, characterized in that: Before the main switch is switched, the voltages across the two thyristor auxiliary modules are both zero.

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