A design method for flexible DC transformer coil

Abstract

The present invention relates to a design method of a flexible DC transformer coil, a spiral closed electrostatic ring structure is designed, the spiral closed electrostatic ring structure is relatively installed at the upper and lower ends of the voltage regulating coil, the shape of one end of the spiral closed electrostatic ring matches the height of the wire spiral at the end of the voltage regulating coil; an oil channel pad is installed between the wires of the voltage regulating coil, and the valve side coil, the grid side coil and the voltage regulating coil are arranged in sequence from the inside to the outside starting from the iron core to form the overall structure of the flexible DC transformer coil. The present invention also relates to a flexible DC transformer coil structure, the self-adhesive transposed wire adopts eight axial wires and is wound to form a single spiral turn structure, the oil channel pad is installed between the self-adhesive transposed wires, the self-adhesive transposed wire is provided with a head fixing brace, and the PET tape is used to bind and fix along the circumferential direction of the coil. The present invention has good integrity, simple structure, can reduce circulating current loss, and is conducive to heat dissipation and ampere-turn balance.

Description

Technical Field

[0001] The invention belongs to the field of transformer manufacturing, and in particular relates to a design method for a flexible DC transformer coil, wherein the voltage regulating coil adopts a single-helix voltage regulating coil structure. Background Art

[0002] Flexible DC transmission technology is the commanding height in the application field of power electronics technology in the world today. It is one of the most controllable and adaptable transmission technologies in the world. It can effectively improve the quality of electric energy and ensure the safe and stable operation of the power grid. The construction of high-voltage flexible DC transmission projects can promote the optimal allocation of energy.

[0003] For flexible DC transformers, when the voltage regulating coil is placed on the outermost side, a layered coil structure is often used. When the number of turns of the voltage regulating coil is small, the height of the voltage regulating coil is too low compared to the height of the internal coil, and there is no oil channel between the turns of the layered coil, which is not conducive to heat dissipation. There are too many radial outlet taps, generally two to three turns per level. During the winding process, each level must cut the wire and handle the insulation of the head. The process is complicated and not conducive to schedule control. When the voltage regulating coil adopts a spiral structure, generally multiple radial wires are wound together and two axial wires are wound together. This winding method is difficult to transpose and difficult to wind, which increases the circulation loss. In addition, the end ring and the electrostatic ring generally adopt an open structure, which is easy to deform and is not conducive to uniform end field strength. In addition, if the end of the voltage regulating coil is flattened, a large triangular area will be formed at the end of the coil during the flattening process. The electric field distribution in this area is extremely uneven, and the copper stranded wire (equipotential line) is greatly bent into the coil. The field strength will be concentrated on the wire cakes on the upper and lower sides of the triangular area, which is prone to discharge, thereby damaging the transformer. A spiral electrostatic ring structure matching the helicity of the voltage regulating coil end face is required. Therefore, the existing coil design method and structure can no longer meet the application requirements of the flexible DC transformer. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a design method and structure of a flexible DC transformer coil, wherein the voltage regulating coil adopts a single spiral voltage regulating coil structure. The technical solution adopted by the present invention is as follows:

[0005] A design method for a flexible DC transformer coil comprises the following steps:

[0006] A single spiral turn structure is wound with a self-adhesive transposed conductor; a spiral closed electrostatic ring structure is designed, and the spiral closed electrostatic ring structure is relatively installed at the upper and lower ends of the single spiral turn structure, and the shape of one end of the spiral closed electrostatic ring matches the spiral height of the conductor at the end of the single spiral turn structure; oil channel gaskets are installed between the conductors of the single spiral turn structure to form a voltage regulating coil; starting from the iron core, the valve side coil, the grid side coil and the voltage regulating coil are arranged in sequence from the inside to the outside to form the overall structure of the flexible DC transformer coil.

[0007] A flexible DC transformer coil structure, using the aforementioned design method for a flexible DC transformer coil, includes: a valve side coil, a grid side coil and a voltage regulating coil, which are arranged in sequence from the inside to the outside of the iron core; the voltage regulating coil includes: a protruding fixed support bar, a self-adhesive transposed conductor, an upper end spiral closed electrostatic ring, a lower end spiral closed electrostatic ring and an oil channel pad, the self-adhesive transposed conductor uses eight axial conductors and is wound to form a single spiral turn structure, the upper end and the lower end of the single spiral turn structure are respectively provided with an upper end spiral closed electrostatic ring and a lower end spiral closed electrostatic ring, the shape of one end of the upper end spiral closed electrostatic ring and the lower end spiral closed electrostatic ring matches the end face spiral height of the single spiral turn structure, and the upper end spiral closed electrostatic ring and the lower end spiral closed electrostatic ring have the same structure. , the assembly direction is opposite, an oil channel pad is installed between the self-adhesive transposed conductors, a head fixing support bar is set at the head of the self-adhesive transposed conductor, and a PET tape is used to bind and fix it along the circumferential direction of the coil; the spiral closed electrostatic ring includes an electrostatic ring skeleton, a copper braided belt, a copper stranded wire and an insulating layer; the electrostatic ring skeleton is a circular closed structure that matches the outer diameter of the single spiral wire turn structure, and the shape of one end of the electrostatic ring skeleton matches the end face spiral height of the single spiral wire turn structure. The outer side of the electrostatic ring skeleton is wrapped with a copper braided belt and an insulating layer in turn, and the copper stranded wire is bent and embedded in the electrostatic ring skeleton at the head position of the corresponding single spiral wire turn structure. The outer surface of the copper stranded wire is wrapped with insulating paper, one end of the copper stranded wire is welded to the copper braided belt, and the other end of the copper stranded wire is led out through the copper braided belt and the insulating layer, and is connected to the first turn wire cake at the end of the single spiral wire turn structure.

[0008] The beneficial effects of the present invention are:

[0009] The design method and structure of a flexible DC transformer coil of the present invention are as follows: eight conductors of a single spiral voltage regulating coil are arranged axially and wound to ensure that the length of each conductor is the same, which can effectively reduce the circulating current loss; the inter-turn refueling channel pad in the height direction can adjust the overall height of the coil, which is beneficial to heat dissipation and ampere-turn balance; a fixed support bar is added to the axial protrusion position to improve the short-circuit resistance of the coil; a closed spiral closed electrostatic ring is used to enhance its anti-deformation ability, which can effectively ensure the roundness of the electrostatic ring and is beneficial to the uniform field strength at the end; a self-adhesive transposed conductor is used to enhance the short-circuit resistance of the coil. The coil structure has good integrity, simple structure, and good processability, and can be widely used in low-loss and large-capacity flexible DC transformers in flexible DC projects with large unit capacities. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the following is a brief introduction to the drawings required for the description of the specific implementation or the prior art. Obviously, the drawings described below are some specific implementations of the present invention. For ordinary technicians in this field, other drawings within the protection scope of this application can be obtained based on these drawings without creative work.

[0011] Figure 1 is a flow chart of a design method for a flexible DC transformer coil according to an embodiment of the present invention;

[0012] Figure 2 is a schematic diagram of the overall structure of a coil according to an embodiment of the present invention;

[0013] Figure 3 is a schematic diagram of the structure of a voltage regulating coil according to an embodiment of the present invention;

[0014] Figure 4 This is a schematic diagram of the wiring principle of the voltage regulating coil according to an embodiment of the present invention;

[0015] Figure 5 Schematic diagram of the appearance of a spiral closed electrostatic ring according to an embodiment of the present invention;

[0016] Figure 6 The embodiment of the present invention Figure 5 D-direction view;

[0017] Figure 7 The embodiment of the present invention Figure 5 AA section intention;

[0018] Figure 8 The embodiment of the present invention Figure 6 BB direction view;

[0019] In the figure, 1 is the iron core, 2 is the valve side coil, 3 is the grid side coil, 4 is the voltage regulating coil, 5 is the head fixing support bar, 6 is the self-adhesive transposition conductor, 7 is the upper end spiral closed electrostatic ring, 8 is the lower end spiral closed electrostatic ring, 9 is the oil channel gasket, 10 is the electrostatic ring skeleton, 11 is the copper braided belt, 12 is the copper stranded wire, and 13 is the insulating layer. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0021] like Figure 1 FIG. 1 is a flow chart of a method for designing a flexible DC transformer coil according to an embodiment of the present invention. A method for designing a flexible DC transformer coil comprises the following steps:

[0022] A single spiral turn structure wound with self-adhesive transposed conductor is used as the main body of the voltage regulating coil.

[0023] Aiming at the problems of extremely uneven electric field distribution at the end of the voltage regulating coil and easy deformation of the open electrostatic ring, a spiral closed electrostatic ring structure is designed. The spiral closed electrostatic ring structure is relatively installed at the upper and lower ends of the single spiral wire turn structure. The shape of one end of the spiral closed electrostatic ring matches the wire spiral height at the end of the single spiral wire turn structure, so as to achieve ampere-turn balance and uniform electric field distribution.

[0024] In order to solve the problem of layered coil height and poor heat dissipation, an oil channel pad is installed between the wires of the voltage regulating coil. The oil channel pad is used to adjust the coil height and form a heat dissipation oil channel.

[0025] In addition, a fixing support bar is provided at the outlet of the conductor, and the conductor is bound and fixed along the circumferential direction of the coil with a PET tape to improve the strength and short-circuit resistance of the voltage regulating coil.

[0026] The valve side coil, the grid side coil and the voltage regulating coil are arranged in sequence from the inside to the outside of the iron core to form the overall structure of the flexible DC transformer coil.

[0027] like Figure 2 The figure is a schematic diagram of the overall structure of the coil of an embodiment of the present invention. A flexible DC transformer coil structure, using the aforementioned design method of a flexible DC transformer coil, includes: a valve side coil 2, a grid side coil 3 and a voltage regulating coil 4, which are arranged in sequence from the inside to the outside of the iron core 1 to form the overall structure of the flexible DC transformer coil.

[0028] like Figure 3The figure shows a schematic diagram of the voltage regulating coil structure of an embodiment of the present invention. The voltage regulating coil 4 comprises: a protruding fixed support bar 5, a self-adhesive transposed conductor 6, a spiral closed electrostatic ring 7 at the upper end, a spiral closed electrostatic ring 8 at the lower end, and an oil channel pad 9. The self-adhesive transposed conductor 6 adopts eight axial conductors and winds them to form a single spiral turn structure, without radially winding conductors, to ensure that the length of each conductor is the same, effectively reducing the circulating current loss, and adopting the self-adhesive transposed conductor to enhance the short-circuit resistance of the coil. The upper and lower ends of the single spiral turn structure have a spiral height, and the upper end and lower end of the single spiral turn structure are respectively provided with an upper end spiral closed electrostatic ring 7 and a lower end spiral closed electrostatic ring 8, and the shape of one end of the upper end spiral closed electrostatic ring 7 and the lower end spiral closed electrostatic ring 8 matches the spiral height of the end face of the single spiral turn structure, and the upper end spiral closed electrostatic ring 7 and the lower end spiral closed electrostatic ring 8 have the same structure and opposite assembly directions; the spiral closed electrostatic ring comprises: an electrostatic ring skeleton, a copper braid and a copper stranded wire, and the copper braid and the copper stranded wire are in the static The outer diameter side of the electrostatic ring skeleton is low-silver brazed. After welding, the copper strands are led to the outer surface of the electrostatic ring skeleton through the opening of the electrostatic ring skeleton. This is conducive to the transition of the copper strands and can prevent the welding point from being broken. The gap on one side of the electrostatic ring skeleton matches the wire spiral height of the single spiral wire turn structure to eliminate the triangular area. The spiral closed electrostatic ring is used to line the end of the single spiral wire turn structure, which greatly reduces the possibility of discharge due to uneven electric field distribution. The closed structure can effectively avoid the electric field shielding problem at the opening of the electrostatic ring and enhance its anti-deformation ability. An oil channel pad 9 is installed between the self-adhesive transposition conductors 6 to adjust the coil height and form an oil channel, which is conducive to ampere-turn balance and heat dissipation; a head fixing support bar 5 is set at the head of the self-adhesive transposition conductor 6, and it is tied and fixed with a PET tape along the circumferential direction of the coil to improve the coil's short-circuit resistance and strength. One of the self-adhesive transposition conductors 6 is connected to the copper strands. After the voltage regulating coil 4 is connected to the grid side coil 3 according to the drawing number, it is connected to the switch. Figure 4 , which is a schematic diagram of the wiring principle of the voltage regulating coil in an embodiment of the present invention. The above wiring methods are all prior arts and will not be described in detail here.

[0029] like Figure 5 , which is a schematic diagram of the appearance of a spiral closed electrostatic ring according to an embodiment of the present invention; Figure 6 As shown, it is an embodiment of the present invention Figure 5D-direction view. A spiral closed electrostatic ring, comprising: an electrostatic ring skeleton 10, a copper braided belt 11, a copper stranded wire 12 and an insulating layer 13. The electrostatic ring skeleton 10 is a circular ring-shaped closed structure that matches the outer diameter of a single spiral wire turn structure. The shape of one end of the electrostatic ring skeleton 10 matches the spiral height of the end face of the single spiral wire turn structure. The outer side of the electrostatic ring skeleton 10 is wrapped with the copper braided belt 11 and the insulating layer 13 in sequence. The material of the electrostatic ring skeleton 10 is laminated cardboard, and the material of the insulating layer 13 is heat-resistant corrugated paper. The electrostatic ring skeleton 10 determines the shape of the electrostatic ring, so that the electrostatic ring can withstand the pressing force; the electrostatic ring skeleton 10 adopts a type in which the upper end face is horizontal and the lower end face matches the spiral height of the upper surface of the single spiral wire turn structure, which avoids the sharp corners caused by the unequal distance between the lower surface of the electrostatic ring and the upper surface of the single spiral wire turn structure, and effectively improves the distribution of the electric field at the end of the coil. The radial cross section of the electrostatic ring skeleton 10 is a rectangle, and the rectangular corners are all rounded. The copper braided belt 11 is half-lapped and evenly wound on the electrostatic ring skeleton 10 , and the insulating layer 13 is half-lapped and wound outside the copper braided belt 11 .

[0030] like Figure 7 As shown, it is an embodiment of the present invention Figure 5 AA cross-section diagram; Figure 8 As shown, it is an embodiment of the present invention Figure 6 BB direction view. The copper stranded wire 12 is bent and embedded in the electrostatic ring frame 10 at the position corresponding to the voltage regulating coil outlet. One end of the copper stranded wire 12 is welded to the copper braided belt 11. The other end of the copper stranded wire 12 is led out through the copper braided belt 11 and the insulating layer 13 and connected to the first turn wire cake at the end of the single spiral turn structure. The copper stranded wire 12 is a 4mm cross-section wire. 2 The bare copper conductor, the outer surface of the copper stranded wire 12 is wrapped with insulating paper. After the copper stranded wire 12 exits the electrostatic ring skeleton 10, it is connected to the single spiral wire turn structure as the electrostatic ring outlet, and the outer surface of the copper stranded wire 12 after exiting the electrostatic ring skeleton 10 is also wrapped with insulating paper. The copper braided belt 11 is low-silver brazed with the copper stranded wire 12. After the welding is completed, the outer surface of the copper stranded wire 12 is wrapped with insulating paper, and the bend is smoothly transitioned to avoid the problem of the copper stranded wire 12 being pulled apart. The bend triangle area is filled with insulating material, and the outer surfaces of the copper stranded wire 12 inside and outside the electrostatic ring skeleton 10 are wrapped with insulating paper, and the insulation wrapping needs to be tight.

[0031] Finally, it should be noted that the above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them, and the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any technician familiar with the technical field can modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be covered within the protection scope of the present invention.

Claims

1. A design method for a flexible DC transformer coil, characterized in that: The following steps are involved: A self-adhesive transposed conductor (6) is used to wind a single spiral turn structure; A spiral closed electrostatic ring structure is designed, and the spiral closed electrostatic ring structure is relatively installed at the upper and lower ends of the single spiral wire turn structure, and the shape of one end of the spiral closed electrostatic ring matches the wire spiral height at the end of the single spiral wire turn structure; An oil channel pad (9) is installed between the self-adhesive transposed conductors (6) of the single spiral turn structure, a head fixing support bar (5) is provided at the head of the conductor, and a PET tape is used to bind and fix the voltage regulating coil (4) along the circumference direction to form the voltage regulating coil (4); A valve side coil (2), a grid side coil (3) and a voltage regulating coil (4) are arranged in sequence from the inside to the outside of the iron core (1) to form an overall structure of the flexible DC transformer coil; A flexible DC transformer coil structure is designed by applying the above-mentioned design method of a flexible DC transformer coil. The voltage regulating coil (4) comprises: a protruding fixed support bar (5), a self-adhesive transposed conductor (6), an upper end spiral closed electrostatic ring (7), a lower end spiral closed electrostatic ring (8) and an oil channel pad (9). The self-adhesive transposed conductor (6) adopts eight axial conductors and is wound to form a single spiral winding structure. The upper end spiral closed electrostatic ring (7) and the lower end spiral closed electrostatic ring (8) are respectively arranged at the upper end and the lower end of the single spiral winding structure. The shape of one end of the upper end spiral closed electrostatic ring (7) and the lower end spiral closed electrostatic ring (8) matches the end face spiral height of the single spiral winding structure. The upper end spiral closed electrostatic ring (7) and the lower end spiral closed electrostatic ring (8) have the same structure and opposite assembly directions. The spiral closed electrostatic ring comprises an electrostatic ring skeleton (10), a copper braided belt (11), a copper stranded wire (12) and an insulating layer (13); the electrostatic ring skeleton (10) is a circular ring-shaped closed structure matching the outer diameter of a single spiral wire turn structure; the shape of one end of the electrostatic ring skeleton (10) matches the end face spiral height of the single spiral wire turn structure; the outer side of the electrostatic ring skeleton (10) is sequentially wrapped with the copper braided belt (11) and the insulating layer (13); the copper stranded wire (12) is bent and embedded in the electrostatic ring skeleton (10) at the position corresponding to the protruding end of the single spiral wire turn structure; the outer surface of the copper stranded wire (12) is wrapped with insulating paper; one end of the copper stranded wire (12) is welded to the copper braided belt (11); the other end of the copper stranded wire (12) is led out through the copper braided belt (11) and the insulating layer (13) and is connected to the first wire turn at the end of the single spiral wire turn structure.

2. The design method of a flexible DC transformer coil according to claim 1, characterized in that: The electrostatic ring skeleton (10) is made of laminated paperboard, and the insulating layer (13) is made of heat-resistant crepe paper.

3. The design method of a flexible DC transformer coil according to claim 1, characterized in that: The radial cross section of the electrostatic ring skeleton (10) is a rectangle, and the corners of the rectangle are rounded.

4. The design method of a flexible DC transformer coil according to claim 1, characterized in that: The copper braided belt (11) is half-lapped and evenly wound on the electrostatic ring frame (10), and the insulating layer (13) is half-lapped and wound outside the copper braided belt (11).

5. The design method of a flexible DC transformer coil according to claim 1, characterized in that: The copper stranded wire (12) is a bare copper wire with a cross-section of 4 mm 2 , and the outer surfaces of the copper stranded wire (12) inside and outside the electrostatic ring frame (10) are wrapped with insulating paper.

6. The design method of a flexible DC transformer coil according to claim 1, characterized in that: The copper braided belt (11) and the copper stranded wire (12) are soldered with low silver.

7. The design method of a flexible DC transformer coil according to claim 6, characterized in that: The bend of the copper stranded wire (12) is smoothly transitioned, and the bend triangle area is filled with insulating material.

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