Single-phase auto-coupling non-excited medium voltage multi-tap voltage regulating transformer and voltage regulating method thereof

Abstract

The present invention belongs to the field of transformer tap regulation and specifically discloses a single-phase auto-coupling, non-excited, medium-voltage, multi-tap voltage-regulating transformer. A voltage-regulating coil is wound on a side column. The voltage-regulating coil includes multiple turns arranged longitudinally, and tapping points are provided on the turns. The tap changer has a double-layer disc structure. Disc A and disc B have the same structure. The discs are provided with a first contact, a second contact, a fixed contact connected to the first contact, a rated contact connectable to the second contact, and a plurality of adjustment contacts. The adjustment contacts are connected to the tapping points on the turns in a one-to-one correspondence. The second contact on disc A is electrically connected to the second contact on disc B. The present invention utilizes a double-layer tap changer to more conveniently adjust the voltage tapping level of the transformer. By adjusting the voltage tapping level, the voltage regulation method of the transformer is simple and convenient, allowing one transformer to serve as a backup phase transformer for multiple transformers, saving costs and avoiding losses caused by system downtime due to transformer failure.

Description

Technical Field

[0001] The invention belongs to the technical field of transformer tap regulation, and in particular relates to a single-phase auto-coupling non-excitation medium-voltage multi-tap voltage regulating transformer. Background Art

[0002] Currently, most of my country's State Grid's 500kV substations operate with single-phase transformers arranged as a three-phase transformer group. Each single-phase transformer has a corresponding backup transformer, but due to cost constraints, these are generally not ordered during the order process. Equipping every substation with a backup transformer would significantly increase the cost of the substation. Without additional backup transformers, if a single-phase transformer in a substation's transformer group fails, the entire group would need to be decommissioned. Having a suitable backup transformer to quickly replace the faulty one would allow for rapid power restoration and minimize the losses caused by the outage.

[0003] Ordinary transformers can only serve as backup phases for transformers of the same model and parameters. Forcing a transformer with different parameters into a substation transformer bank can create safety hazards and lead to higher losses. To enable a transformer to serve as a backup phase for transformers of different models and parameters, developing a transformer with flexible voltage tapping adjustment has become an urgent issue. Summary of the Invention

[0004] The present invention provides a single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer and a voltage regulating method thereof, which are used to solve the problem that when a transformer group in a current substation fails, there is no suitable spare phase to replace it, which will cause great losses.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows: a single-phase auto-coupling non-excited medium voltage multi-tap regulating transformer, comprising: an oil tank, an iron core arranged in the oil tank, a side column fixed to one side of the iron core, and a tap changer fixed to the oil tank;

[0006] The side column is wound with an excitation coil and a voltage regulating coil in sequence from the inside to the outside; the voltage regulating coil is a multi-spiral coil, including a plurality of turns arranged longitudinally, and a tap point is provided on the turns;

[0007] The tap changer has a double-layer disc structure, including disc A and disc B. Disc A and disc B have the same structure and are provided with a first contact, a second contact, a fixed contact connected to the first contact, a rated contact connectable to the second contact, and several adjustment contacts. The second contact is electrically connected to one of the rated contact and the several adjustment contacts to adjust the transformer voltage tap level. The adjustment contacts are connected to the tap points on the turns in a one-to-one correspondence. The second contact on disc A is electrically connected to the second contact on disc B.

[0008] In a preferred embodiment of the present invention, a low-voltage coil, a medium-voltage coil and a high-voltage coil are wound on the core column from the inside to the outside in sequence. The low-voltage coil has a spiral end-type wire feed, the medium-voltage coil has a continuous end-type wire feed, and the high-voltage coil has an inner-screen continuous middle-type wire feed.

[0009] In a preferred embodiment of the present invention, the low-voltage coil is made of a self-adhesive transposed mesh-wrapped conductor, the medium-voltage coil, high-voltage coil, and excitation coil are made of a self-adhesive transposed paper-wrapped conductor, and the voltage regulating coil is made of a combined paper-wrapped conductor.

[0010] In a preferred embodiment of the present invention, an electrostatic plate is provided at the end of the outlet terminal of the medium voltage coil, and an electrostatic plate is provided at the end of the outlet terminal of the high voltage coil.

[0011] In a preferred embodiment of the present invention, an upper iron yoke is fixedly provided on the top of the iron core column, a lower iron yoke is fixedly provided on the bottom of the iron core column, and the upper and lower parts of the high-voltage coil and the medium-voltage coil are provided with lung-type magnetic shielding plates; the inner wall of the high-pressure side of the oil tank is provided with a plurality of rolled strip-shaped magnetic shielding parts, and the inner wall of the low-pressure side is provided with a plurality of rolled strip-shaped magnetic shielding parts.

[0012] In a preferred embodiment of the present invention, the medium voltage coil is connected in parallel with the excitation coil, and the high voltage coil includes an upper high voltage coil and a lower high voltage coil arranged in parallel, and the end outlet terminal of the upper high voltage coil and the end outlet terminal of the lower high voltage coil are electrically connected to the first outlet terminal of the medium voltage coil.

[0013] In a preferred embodiment of the present invention, the voltage regulating coil includes a plurality of turns arranged longitudinally and connected in series, the end of the turns is the regulating tap point, the first end of the voltage regulating coil is the rated tap point, the rated tap point is electrically connected to the rated contact, and the regulating tap point is connected to the regulating contact in a one-to-one correspondence.

[0014] In a preferred embodiment of the present invention, two adjacent turns are connected via a copper rod, and the copper rod is electrically connected to the corresponding contact.

[0015] In a preferred embodiment of the present invention, the fixed contact of the disk a is electrically connected to the medium voltage bushing, and the fixed contact of the disk b is electrically connected to the first outlet terminal of the medium voltage coil.

[0016] The present invention also discloses a voltage regulation method for a single-phase auto-coupling non-excitation medium-voltage multi-tap voltage-regulating transformer, which comprises the following steps:

[0017] When the target voltage is positive tap, the second contact of disk a is connected to the rated contact of disk a, and the positive tap adjustment is achieved by changing the adjustment contact of disk b connected to the second contact of disk b;

[0018] When the target voltage is negative tap, the second contact of disk b is connected to the rated contact of disk b, and the negative tap adjustment is achieved by changing the adjustment contact of disk a connected to the second contact of disk a;

[0019] When the target voltage is the rated tap, the second contact of disk a is electrically connected to the rated contact of disk a, and the second contact of disk b is electrically connected to the rated contact of disk b.

[0020] In a preferred embodiment of the present invention, when the target voltage is positive tap, starting from the rated contact of disk b, the second contact of disk b is sequentially connected to each adjustment contact arranged clockwise or counterclockwise on disk b, and the rated tap level decreases sequentially.

[0021] In a preferred embodiment of the present invention, when the target voltage is negative tap, starting from the rated contact of disk a, the second contact of disk a is sequentially connected to each adjustment contact arranged clockwise or counterclockwise on disk a, and the rated tap level increases sequentially.

[0022] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0023] The present invention provides a single-phase auto-coupling non-excited medium-voltage multi-tap voltage-regulating transformer and a voltage regulation method thereof. A double-layer tap changer is adopted, which can more conveniently adjust the voltage tap level of the transformer. By adjusting the voltage tap level, the voltage regulation method of the transformer is simple and convenient, so that one transformer can serve as a backup phase transformer for multiple transformers, which not only saves costs but also avoids losses caused by system shutdown due to transformer failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, they can also obtain drawings of other embodiments based on these drawings.

[0025] Figure 1It is a top view of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention;

[0026] Figure 2 This is a lead connection diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention;

[0027] Figure 3 Schematic diagram of the magnetic shielding structure of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention;

[0028] Figure 4 This is a wiring schematic diagram of a single-phase auto-coupled non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is +1%;

[0029] Figure 5 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is +2%;

[0030] Figure 6 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is +3%;

[0031] Figure 7 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is +4%;

[0032] Figure 8 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer described in one embodiment of the present invention when the tapping level is +5%;

[0033] Figure 9 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is -1%;

[0034] Figure 10 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is -2%;

[0035] Figure 11 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tap level is -3%;

[0036] Figure 12 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is -4%;

[0037] Figure 13 This is a wiring schematic diagram of a single-phase auto-coupling non-excited medium-voltage multi-tap voltage regulating transformer according to one embodiment of the present invention when the tapping level is -5%;

[0038] Figure 14 The present invention is a wiring schematic diagram of a single-phase auto-coupled non-excited medium-voltage multi-tap voltage regulating transformer according to an embodiment of the present invention when the tapping level is the rated tapping.

[0039] As shown in the figure: 101-side column; 102-iron core column; 103-side yoke; 104-upper iron yoke; 105-lower iron yoke; 201-low-voltage coil; 202-medium-voltage coil; 203-high-voltage coil; 204-excitation coil; 205-voltage regulating coil; 2051-copper rod; 206-static plate; 301-magnetic shielding plate; 302-magnetic shielding component; 401-tap changer. DETAILED DESCRIPTION

[0040] For ease of understanding, the single-phase auto-coupling non-excited medium voltage multi-tap voltage regulating transformer and its voltage regulation method are described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0041] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations and positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0043] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0044] The present invention discloses a single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer, such as Figure 1 As shown, the transformer comprises an oil tank, an iron core 102 disposed within the oil tank, a low-voltage coil 201, a medium-voltage coil 202, and a high-voltage coil 203 wound sequentially around the iron core 102 from the inside out, a side leg 101 fixed to one side of the iron core 102, an excitation coil 204 and a voltage regulating coil 205 wound sequentially around the side leg 101 from the inside out, a tap changer 401 fixed to the oil tank, and a side yoke 103 fixed to the other side of the iron core 102. The present invention employs a single-phase three-leg iron core structure, which effectively reduces coil leakage while meeting product technical parameters, thereby reducing transformer stray losses.

[0045] The low-voltage coil 201 is made of a self-adhesive transposed mesh-wrapped conductor, and the end portion is spirally fed.

[0046] The medium voltage coil 202 is made of self-adhesive transposed paper-wrapped conductor and has a continuous end-in line. An electrostatic plate 206 is provided at the end of the outlet end of the medium voltage coil 202 .

[0047] The high-voltage coil 203 is made of self-adhesive transposed paper-covered conductors. It features an internally shielded, continuous central feeder, and an electrostatic plate 206 is installed at the outlet of the high-voltage coil 203. The high-voltage coil 203 comprises an upper high-voltage coil 203 and a lower high-voltage coil 203 connected in parallel. The terminal outlets of the upper and lower high-voltage coils 203 are electrically connected to the first outlet of the medium-voltage coil 202.

[0048] like Figure 2-3 As shown, an upper iron yoke 104 is fixedly provided on the top of the iron core column 102, a lower iron yoke 105 is fixedly provided on the bottom of the iron core column 102, and lung-type magnetic shielding plates 301 are provided on the upper and lower parts of the high-voltage coil 203 and the medium-voltage coil 202; the inner wall of the high-pressure side of the oil tank is provided with longitudinally arranged parallel rolled strip magnetic shielding parts 302, and the inner wall of the low-pressure side is also provided with longitudinally arranged parallel rolled strip magnetic shielding parts 302.

[0049] The magnetic leakage of the transformer coil increases with the increase of the transformer capacity. An upper magnetic shield plate and a lower magnetic shield plate are set at the upper and lower ends of the coil, and a magnetic leakage control system with vertical magnetic shield plates is added to provide two paths for the magnetic leakage of the coil. One is a leakage magnetic circuit formed by the upper iron yoke 104, the lower iron yoke 105, a side column 101, and a side yoke 103 through the upper magnetic shield plate and the lower magnetic shield plate. The other is a circuit formed by the magnetic shielding of the upper and lower ends of the device body and the magnetic shielding of the vertical oil tank. This solves the problem of overheating of the iron core structure and the oil tank structure caused by the magnetic leakage of the coil.

[0050] The excitation coil 204 is made of self-adhesive transposed paper-wrapped wire, and the excitation coil 204 is connected in parallel with the medium voltage coil 202.

[0051] The voltage regulating coil 205 is made of a composite paper-covered conductor and is a multi-spiral coil consisting of multiple turns arranged longitudinally, each with a tapping point. The voltage regulating coil 205 comprises several turns arranged longitudinally and connected in series. The end of each turn serves as the regulating tapping point, while the beginning of the voltage regulating coil 205 serves as the rated tapping point. The rated tapping point is electrically connected to the rated contact, and the regulating tapping point is connected one-to-one with the regulating contact. Adjacent turns are connected by copper rods 2051, which are electrically connected to corresponding contacts. The fixed contact of disk a is electrically connected to the medium-voltage bushing, while the fixed contact of disk b is electrically connected to the beginning of the medium-voltage coil 202.

[0052] Tap changer 401 is a double-layered disc structure, comprising discs A and B. Discs A and B share the same structure and are equipped with a first contact, a second contact, a fixed contact connected to the first contact, a rated contact connectable to the second contact, and several adjustable contacts. The adjustable contacts are connected one-to-one with the tap points on the turns. The second contact on disc A is electrically connected to the second contact on disc B. The fixed contact on disc A is electrically connected to the medium-voltage bushing, while the fixed contact on disc B is electrically connected to the first outlet terminal of the medium-voltage coil 202.

[0053] In one embodiment of the present invention, the voltage between the voltage regulating coil 205 and the tap changer 401 is 220 kV. To achieve a voltage regulation of ±5×1%, the voltage regulating coil 205 includes five turns, namely a first turn, a second turn, a third turn, a fourth turn, and a fifth turn. The terminal end of the first turn is a first tap point, the terminal end of the second turn is a second tap point, the terminal end of the third turn is a third tap point, the terminal end of the fourth turn is a fourth tap point, the terminal end of the fifth turn is a fifth tap point, and the terminal end of the fifth turn is a sixth tap point.

[0054] Adjacent turns are connected via copper rods 2051, and the tapping points are electrically connected to corresponding contacts via copper rods 2051. The upper and lower taps of the voltage regulating coil 205 are first connected end-to-end to the upper and lower ends of the longitudinally arranged copper rods 2051. Cables are then connected through two sets of terminals at the upper and lower ends of copper rods 2051 to the corresponding contacts on the a and b plates of the tap changer 401. The tap changer 401 operates to achieve a ±5×1% voltage regulation.

[0055] Specifically, disk A includes a K contact, a first contact, a second contact, a third contact, a fourth contact, a fifth contact, and six sixth contacts connected in series. The K contact is a fixed contact, the first, second, third, fourth, and fifth contacts are adjustable contacts, and the sixth contact is a rated contact. The K contact is electrically connected to the medium-voltage bushing, the first contact is electrically connected to the first tap, the second contact is electrically connected to the second tap, the third contact is electrically connected to the third tap, the fourth contact is electrically connected to the fourth tap, the fifth contact is electrically connected to the fifth tap, and the sixth contact is electrically connected to the sixth tap.

[0056] The b-disk includes an O contact, a first contact, a second contact, a third contact, a fourth contact, a fifth contact, and six sixth contacts connected in series. The O contact is a fixed contact, the first, second, third, fourth, and fifth contacts are adjustable contacts, and the sixth contact is a rated contact. The O contact is electrically connected to the first outlet terminal of the medium voltage coil 202. The first contact is electrically connected to the first tap, the second contact is electrically connected to the second tap, the third contact is electrically connected to the third tap, the fourth contact is electrically connected to the fourth tap, the fifth contact is electrically connected to the fifth tap, and the sixth contact is electrically connected to the sixth tap.

[0057] The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer in the present invention has the following voltage regulating method.

[0058] When the target voltage is a positive tap, the second contact of disk a is connected to the rated contact of disk a. Positive tap adjustment is achieved by changing the regulating contact of disk b, which is connected to the second contact of disk b. Starting from the rated contact of disk b, the second contact of disk b is connected to each regulating contact arranged clockwise or counterclockwise on disk b in sequence, and the rated tap level decreases in sequence.

[0059] like Figure 4 As shown, specifically, when the target voltage is +1% tap, the first contact of disk a is connected to the K contact, the second contact is connected to the sixth contact, and the first contact of disk b is connected to the O contact, the second contact is connected to the fifth contact;

[0060] like Figure 5 As shown, when the target voltage is +2% tap, the first contact of disk a is connected to contact K, and the second contact is connected to contact 6; the first contact of disk b is connected to contact O, and the second contact is connected to contact 4;

[0061] like Figure 6 As shown, when the target voltage is +3% tap, the first contact of disk a is connected to the K contact, the second contact is connected to the sixth contact, and the first contact of disk b is connected to the O contact, the second contact is connected to the third contact;

[0062] like Figure 7As shown, when the target voltage is +4% tap, the first contact of disk a is connected to the K contact, the second contact is connected to the sixth contact, and the first contact of disk b is connected to the O contact, the second contact is connected to the second contact;

[0063] like Figure 8 As shown, when the target voltage is +5% tap, the first contact of disk a is connected to the K contact, and the second contact is connected to the sixth contact; the first contact of disk b is connected to the O contact, and the second contact is connected to the first contact.

[0064] When the target voltage is a negative tap, the second contact of disk B is connected to the rated contact of disk B. Negative tap adjustment is achieved by changing the regulating contact of disk A, which is connected to the second contact of disk A. Starting from the rated contact of disk A, the second contact of disk A is connected to each regulating contact arranged clockwise or counterclockwise on disk A, and the rated tap level increases successively.

[0065] Specifically, if Figure 9 As shown, when the target voltage is -1% tap, the first contact of disk a is connected to contact K, and the second contact is connected to contact 5; the first contact of disk b is connected to contact O, and the second contact is connected to contact 6;

[0066] like Figure 10 As shown, when the target voltage is -2% tap, the first contact of disk a is connected to the K contact, and the second contact is connected to the fourth contact; the first contact of disk b is connected to the O contact, and the second contact is connected to the sixth contact;

[0067] like Figure 11 As shown, when the target voltage is -3% tap, the first contact of disk a is connected to contact K, and the second contact is connected to contact 3; the first contact of disk b is connected to contact O, and the second contact is connected to contact 6;

[0068] like Figure 12 As shown, when the target voltage is -4% tap, the first contact of disk a is connected to the K contact, and the second contact is connected to the second contact; the first contact of disk b is connected to the O contact, and the second contact is connected to the sixth contact;

[0069] like Figure 13 As shown, when the target voltage is -5% tap, the first contact of disk a is electrically connected to the K contact, and the second contact is electrically connected to the first contact; the first contact of disk b is connected to the O contact, and the second contact is connected to the sixth contact.

[0070] like Figure 14 As shown, when the target voltage is the rated tap, the first contact of disk a is connected to the K contact, and the second contact is connected to the sixth contact; the first contact of disk b is connected to the O contact, and the second contact is connected to the sixth contact.

[0071] The present invention provides a single-phase auto-coupling non-excited medium-voltage multi-tap voltage-regulating transformer and a voltage regulation method thereof. A double-layer tap changer is adopted, which can more conveniently adjust the voltage tap level of the transformer. By adjusting the voltage tap level, the voltage regulation method of the transformer is simple and convenient, so that one transformer can serve as a backup phase transformer for multiple transformers, which not only saves costs but also avoids losses caused by system shutdown due to transformer failure.

[0072] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art will appreciate that the technical solutions described in the above embodiments may be modified or some or all of the technical features thereof may be replaced with equivalents, and that such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the various embodiments of the present invention.

Claims

1. A single-phase auto-coupling non-excited medium voltage multi-tap voltage regulating transformer, characterized in that: include: An oil tank, an iron core disposed in the oil tank, a side column located on one side of the iron core, and a tap changer fixed to the oil tank; The side column is wound with an excitation coil and a voltage regulating coil in sequence from the inside to the outside; the voltage regulating coil is a multi-spiral coil, including a plurality of turns arranged longitudinally, and a tap point is provided on the turns; The tap changer has a double-layer disc structure, including disc A and disc B. Disc A and disc B have the same structure and are provided with a first contact, a second contact, a fixed contact connected to the first contact, a rated contact connectable to the second contact, and several adjustment contacts. The second contact is electrically connected to one of the rated contact and the several adjustment contacts to adjust the transformer voltage tap level. The adjustment contacts are connected to the tap points on the turns in a one-to-one correspondence. The second contact on disc A is electrically connected to the second contact on disc B.

2. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 1, characterized in that: The iron core column is wound with low-voltage coil, medium-voltage coil and high-voltage coil in sequence from the inside to the outside. The low-voltage coil has a spiral wire feed at the end, the medium-voltage coil has a continuous wire feed at the end, and the high-voltage coil has an inner-screen continuous middle wire feed.

3. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 2, characterized in that: The low-voltage coil is made of a self-adhesive transposed mesh-wrapped conductor, the medium-voltage coil, high-voltage coil, and excitation coil are made of a self-adhesive transposed paper-wrapped conductor, and the voltage regulating coil is made of a combined paper-wrapped conductor.

4. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 2, characterized in that: An electrostatic plate is provided at the end of the outlet terminal of the medium voltage coil, and an electrostatic plate is provided at the end of the outlet terminal of the high voltage coil.

5. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 2, characterized in that: An upper iron yoke is fixedly provided on the top of the iron core column, a lower iron yoke is fixedly provided on the bottom of the iron core column, and lung-type magnetic shielding plates are provided on the upper and lower parts of the high-voltage coil and the medium-voltage coil; a plurality of rolled strip-shaped magnetic shielding parts are provided on the inner wall of the high-pressure side of the oil tank, and a plurality of rolled strip-shaped magnetic shielding parts are provided on the inner wall of the low-pressure side.

6. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 2, characterized in that: The medium voltage coil is connected in parallel with the excitation coil, and the high voltage coil includes an upper high voltage coil and a lower high voltage coil arranged in parallel. The end outlet of the upper high voltage coil and the end outlet of the lower high voltage coil are electrically connected to the first outlet of the medium voltage coil.

7. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 1, characterized in that: The voltage regulating coil includes a plurality of turns arranged longitudinally and connected in series in sequence. The end of the turns is the regulating tap point, the first end of the voltage regulating coil is the rated tap point, the rated tap point is electrically connected to the rated contact, and the regulating tap point is connected to the regulating contact in a one-to-one correspondence.

8. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 7, characterized in that: Two adjacent turns are connected via a copper rod, and the copper rod is electrically connected to the corresponding contact.

9. The single-phase auto-coupling non-excitation medium voltage multi-tap voltage regulating transformer according to claim 1, characterized in that: The fixed contact of the a disk is electrically connected to the medium voltage bushing, and the fixed contact of the b disk is electrically connected to the first outlet terminal of the medium voltage coil.

10. A voltage regulation method for a single-phase auto-coupling non-excited medium voltage multi-tap voltage regulating transformer according to any one of claims 1 to 9, characterized in that: The following steps are involved: When the target voltage is positive tap, the second contact of disk a is connected to the rated contact of disk a, and the positive tap adjustment is achieved by changing the adjustment contact of disk b connected to the second contact of disk b; When the target voltage is negative tap, the second contact of disk b is connected to the rated contact of disk b, and the negative tap adjustment is achieved by changing the adjustment contact of disk a connected to the second contact of disk a; When the target voltage is the rated tap, the second contact of disk a is electrically connected to the rated contact of disk a, and the second contact of disk b is electrically connected to the rated contact of disk b.

11. The voltage regulation method of a single-phase auto-coupling non-excited medium voltage multi-tap voltage regulating transformer according to claim 10, characterized in that: When the target voltage is positive tap, starting from the rated contact of disk b, the second contact of disk b is connected to the adjustment contacts arranged clockwise or counterclockwise on disk b in sequence, and the rated tap level decreases in sequence.

12. The voltage regulation method of a single-phase auto-coupling non-excited medium voltage multi-tap voltage regulating transformer according to claim 10, characterized in that: When the target voltage is negative tap, starting from the rated contact of disk a, the second contact of disk a is connected to the adjustment contacts arranged clockwise or counterclockwise on disk a in sequence, and the rated tap level increases in sequence.

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