Novel cushion block structure for inhibiting corona at end part of generator stator winding

Abstract

The utility model relates to the field of generator stator winding insulation, in particular to a novel cushion block structure for inhibiting corona at the end part of a generator stator winding. A novel cushion block structure for inhibiting corona at the end part of a generator stator winding is characterized in that the novel cushion block structure comprises two winding bars, a cushion block is clamped between the two winding bars, two sides of the end part of the cushion block extend away from each other to form butt joint blocks, and a rope binding groove for binding a binding rope is arranged in the lateral direction of the cushion block. A first binding rope is bound on the cushion block and the winding bars along the butt joint block and wound around the surfaces of the two winding bars, and a second binding rope perpendicular to the first binding rope is bound on the cushion block along the binding rope groove. According to the utility model, the cushion block structure is optimized, so that the surface field intensity of the cushion block is reduced, and the optimized cushion block structure is beneficial to reducing the risk of corona at the binding part.

Description

Technical Field

[0001] This utility model relates to the field of generator stator winding insulation, specifically to a novel pad structure for suppressing corona discharge at the ends of generator stator windings. Background Technology

[0002] Corona discharge at the stator winding ends of large air-cooled generator sets is a common fault, especially at high altitudes. Low air pressure and density reduce the surface discharge voltage of the stator bars and windings of large-capacity hydro-generators, making the corona discharge problem more prominent. In particular, when these areas with extremely uneven electric field distribution are tied at the stator winding ends, the small gaps and surface burrs between insulating fixing components (pads, felt, etc.) and between the components and the stator bars accelerate the occurrence and development of corona discharge.

[0003] Currently, to address the issue of uneven electric field distribution in areas where stator windings are bound at the ends, the most common methods to suppress corona generation are impregnating the insulating fixing structure with resin and applying putty to the gaps. While these methods are effective to some extent, they are time-consuming, labor-intensive, and inefficient. Furthermore, it is difficult to reduce the presence of air gaps inside the binding ropes by applying putty, thus failing to completely eliminate air gaps structurally. Utility Model Content

[0004] To address the shortcomings of existing technologies, such as localized electric field distortion and excessively high potential difference at the binding point between the binding rope and the rod, this invention provides a novel pad structure for suppressing corona discharge at the end of a generator stator winding:

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a novel pad structure for suppressing corona at the end of a generator stator winding, characterized in that it includes two rods, a pad is sandwiched between the two rods, the two sides of the end of the pad extend away from each other to form a mating block, and the pad has a binding groove for binding ropes on its side, a first binding rope is bound around the surface of the two rods along the mating block on the pad and the rods, and a second binding rope is bound along the binding groove perpendicular to the first binding rope on the pad.

[0006] Furthermore, the angle between the mating block and the pad block has an arc-shaped surface, which is consistent with the fillet radius of the wire rod.

[0007] Furthermore, the surface on which the pad adheres to the wire rod is the first surface, and the first surface between the two arc-shaped surfaces adheres to the wire rod along with the two arc-shaped surfaces.

[0008] Furthermore, the side of the pad located between the two wire rods is the second surface, and the rope groove is provided through the second surface along the length of the pad.

[0009] Furthermore, the pad has symmetrically arranged mating blocks at both ends, and a groove that fits the wire bar is formed between the two mating blocks in the length direction of the pad.

[0010] Furthermore, the two ends of the rope groove along its length have rounded corners between them and the side of the pad.

[0011] Furthermore, the distance between the far end of the docking block perpendicularly connected to the first surface and the first surface is greater than the fillet radius of the wire rod.

[0012] Furthermore, the distance between the far end of the docking block perpendicularly connected to the first surface and the first surface is equal to the fillet radius of the wire rod.

[0013] Furthermore, the outer surfaces of the two mating blocks at one end of the pad are the third surface, and the mating blocks on the third surface have rounded corners. After the first binding rope is impregnated with glue, it is vertically bound and fixed along the third surface and the two wire rods. After the second binding rope is impregnated with glue, it is horizontally bound and fixed along the binding rope groove and the first binding rope.

[0014] Furthermore, a felt impregnated with adhesive is provided between the contact surface of the pad and the wire bar.

[0015] In summary, this utility model has the following beneficial effects: the extended portion of the pad's end contacts the wire rod. To avoid gaps between the pad and the wire rod, the chamfer of the extended portion of the pad is consistent with the rounded corner radius of the four sides of the wire rod, thus better positioning the pad between the two wire rods and facilitating subsequent fixing with binding ropes. Furthermore, by using glue-impregnated felt to adapt the contact surfaces of the pad and the wire rod, gaps between the contact surfaces of the pad and the wire rod can be effectively eliminated. Simultaneously, a first binding rope is vertically wrapped along the outer surface of the pad and the wire rod, and a second binding rope is horizontally wrapped along the binding rope groove, thereby fixing the pad. Attached Figure Description

[0016] Figure 1 This is a structural diagram of a pad block with a connecting block at one end.

[0017] Figure 2 This is a structural diagram of the pad block.

[0018] Figure 3 This is a diagram of another type of pad structure.

[0019] Figure 4 This is a schematic diagram of the installation of the pad and the wire rod.

[0020] Figure 5 This is a schematic diagram of binding the pad and the wire rod.

[0021] Figure 6 Electric field distribution when air bubbles are present at the binding point of the rope Figure 1 .

[0022] Figure 7Electric field distribution when air bubbles are present at the binding point of the rope Figure 2 .

[0023] Figure 8 The simulation calculation diagram shows the two-dimensional cross-section at the bubble location.

[0024] Figure 9 The simulation diagram shows the two-dimensional cross-section where the burr exists.

[0025] Figure 10 This is a diagram showing the overall potential distribution of the winding under rated voltage.

[0026] Figure 11 To optimize the electric field distribution at the contact area between the pad block and the wire rod surface.

[0027] The attached diagrams are described as follows: 1. Wire rod; 11. Rounded corner of wire rod; 2. Pad block; 21. Rope binding groove; 3. Connecting block; 31. Arc-shaped surface; 32. First surface; 33. Second surface; 34. Third surface; 35. Rounded corner of connecting block; 4. First binding rope; 5. Second binding rope. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the embodiments.

[0029] Simulation calculations for ordinary pad binding with air bubbles and burrs:

[0030] When using ordinary spacers in the winding, air bubbles, gaps, and burrs are unavoidable at the binding points. In this case, when air bubbles and burrs are present, the electric field distribution at the spacer is as follows: Figure 6 and Figure 7 As shown.

[0031] Near the edge of the pad, a discontinuous cylinder with a diameter of 2mm was constructed. The continuous cylinder served as an air gap inside the binding rope in case of poor binding. Simulation calculations were then performed at a voltage of 1.1Un, and the results are as follows. Figure 6 and Figure 7 As shown in the diagram. The calculation results show that when bubbles are present, the electric field strength at the bubble edge is significantly higher than at other locations, and the bubble length has a relatively small impact on the electric field. While the presence of bubbles does increase the electric field strength at the bubble location, the increase is not substantial. Figure 8 The two-dimensional cross-section at the bubble shows that the maximum electric field strength at the bubble is 1.24 kV / mm.

[0032] When burrs exist in the binding gap, the simulation calculation results are as follows: Figure 9 As shown in the figure. The calculation results show that when burrs are present, the electric field strength at the tip of the burr is the largest, which is 3.69 kV / mm. This exceeds the breakdown field strength of air under normal conditions, and its value is much higher than that of air bubbles. This indicates that the hazards of burrs in the binding are more serious than those of air bubbles.

[0033] Example 1:

[0034] like Figure 1 and Figure 2 As shown, a novel pad structure for suppressing corona at the end of a generator stator winding includes two rods 1, with a pad 2 sandwiched between the two rods 1. The two sides of the end of the pad 2 extend away from each other to form a mating block 3, and the pad 2 has a binding groove 21 for binding ropes on its side. A first binding rope 4 is bound around the surface of the two rods 1 along the mating block 3 on the pad 2 and the first binding rope 4 is bound to the pad 2 along the binding groove 21 perpendicular to the first binding rope 4.

[0035] By changing the structure of the pad 2 used during binding, small gaps and surface burrs between the pad 2 and the felt, as well as between the pad 2 and the stator winding 1, are avoided, thereby uniformly distributing the electric field at the binding part of the stator winding, reducing the surface potential of the stator winding, and thus suppressing the corona discharge of the generator stator winding.

[0036] In implementation, the angle between the mating block 3 and the pad block 2 has an arc-shaped surface 31, which is consistent with the fillet 11 of the rod. The surface of the pad block 2 that is in contact with the rod 1 is the first surface 32, and the first surface 32 between the two arc-shaped surfaces 31 is in contact with the rod 1. The side of the pad block 2 located between the two rods 1 is the second surface 33, and the rope groove 21 is provided through the second surface 33 along the length direction of the pad block 2. The pad block 2 has symmetrical mating blocks 3 at both ends, and the two mating blocks 3 in the length direction of the pad block 2 form a groove that fits the rod 1. The pad block 2 has a second rope 5 formed through the length direction on both sides.

[0037] In practice, the two ends of the rope groove 21 along its length have rounded corners 21 between them and the side of the pad block 2.

[0038] A rubber-impregnated felt is provided between the contact surfaces of the pad 2 and the wire rod 1.

[0039] like Figure 5 As shown, the outer surface of the two connecting blocks 3 at one end of the pad block 2 is the third surface 34. After the first binding rope is impregnated with glue, it is vertically bound and fixed along the third surface 34 and the two wire rods 1. After the second binding rope is impregnated with glue, it is horizontally bound and fixed along the binding rope groove 21 and the first binding rope.

[0040] Example 2:

[0041] As shown in the figure, a novel pad structure for suppressing corona at the end of a generator stator winding includes two rods 1, with a pad 2 sandwiched between the two rods 1. The two sides of the end of the pad 2 extend away from each other to form a connecting block 3, and the pad 2 has a binding groove 21 for binding ropes on its side. A first binding rope 4 is bound around the surface of the two rods 1 along the connecting block 3 on the pad 2 and the first binding rope 4. A second binding rope 5 is bound to the pad 2 along the binding groove 21 perpendicular to the first binding rope 4.

[0042] In implementation, the following is true Figure 3 As shown, there is an arc-shaped surface 31 between the angle between the mating block 3 and the pad block 2, and the arc-shaped surface 31 is consistent with the fillet 11 of the wire rod. The surface of the pad block 2 that is in contact with the wire rod 1 is the first surface 32, and the first surface 32 between the two arc-shaped surfaces 31 is in contact with the wire rod 1. The side of the pad block 2 located between the two wire rods 1 is the second surface 33, and the rope binding groove 21 is provided through the second surface 33 along the length direction of the pad block 2. The pad block 2 is symmetrically provided with mating blocks 3 at both ends, and the two mating blocks 3 in the length direction of the pad block 2 form a groove that is adapted to the wire rod 1. The pad 2 has two sides extending along its length to form a second binding rope 5. Both ends of the pad 2 are symmetrically provided with connecting blocks 3, which are combined with the pad 2 to form an arc dumbbell shape, thus avoiding the generation of gaps between the pad 2 and the winding rod 1. At the same time, a groove is made in the middle of the pad 2. When binding and fixing, the binding rope with glue is placed in the groove 21, which further avoids gaps and burrs between the binding rope and the rod 1, thereby effectively avoiding the generation of corona.

[0043] In practice, the distance between the far end of the mating block 3 that is perpendicular to the first surface 32 and the first surface 32 is greater than the fillet 11 of the wire rod, so that the pad block 2 and the wire rod 1 can be stably fixed.

[0044] As an alternative, the distance between the far end of the docking block 3 that is vertically connected to the first surface 32 and the first surface 32 is equal to the fillet 11 of the wire rod.

[0045] The outer surfaces of the two connecting blocks 3 at one end of the pad block 2 are the third surface 34. The connecting block 3 has a rounded corner 35 on the third surface 34. After the first binding rope is impregnated with glue, it is vertically bound and fixed along the third surface 34 and the two wire rods 1. After the second binding rope is impregnated with glue, it is horizontally bound and fixed along the binding rope groove 21 and the first binding rope.

[0046] Optimized pad block simulation calculation:

[0047] The simplified model was imported into COMSOL for simulation calculations. During the calculation, one copper conductor rod was used as the high-voltage end, with an applied voltage of 18kV, and the other copper conductor rod was used as the grounding end. The potential distribution at the contact point between the pad and the surface of the conductor rod under power frequency is as follows: Figure 10 As shown.

[0048] From simulation results Figure 11 It can be seen that the maximum electric field at the contact surface between the pad and the wire is 0.65kV / mm. The optimization of the pad structure reduces the electric field strength on the pad surface, indicating that the optimized pad structure helps to reduce the risk of corona at the binding site.

[0049] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A novel pad structure for suppressing corona discharge at the ends of generator stator windings, characterized in that, It includes two rods (1), a pad (2) sandwiched between the two rods (1), the two sides of the end of the pad (2) extend away from each other to form a connecting block (3), and the pad (2) has a rope groove (21) for binding ropes on the side. The pad (2) and the rod (1) are bound with a first rope (4) along the connecting block (3) around the surface of the two rods (1). The pad (2) is bound with a second rope (5) along the rope groove (21) perpendicular to the first rope (4).

2. The novel pad structure for suppressing corona discharge at the end of a generator stator winding according to claim 1, characterized in that, The angle between the docking block (3) and the pad block (2) has an arc-shaped surface (31), which is consistent with the fillet (11) of the wire rod.

3. The novel pad structure for suppressing corona at the end of a generator stator winding according to claim 2, characterized in that, The surface of the pad (2) that is in contact with the wire rod (1) is the first surface (32), and the first surface (32) between the two arc surfaces (31) is in contact with the wire rod (1).

4. The novel pad structure for suppressing corona at the end of a generator stator winding according to claim 3, characterized in that, The side of the pad (2) located between the two wire rods (1) is the second surface (33), and the rope groove (21) is provided on the second surface (33) through the length of the pad (2).

5. The novel pad structure for suppressing corona at the end of a generator stator winding according to claim 4, characterized in that, The pad (2) is provided with symmetrical docking blocks (3) at both ends, and a slot is formed between the two docking blocks (3) in the length direction of the pad (2) to fit the wire rod (1).

6. The novel pad structure for suppressing corona at the end of a generator stator winding according to claim 3 or 4, characterized in that, The two ends of the rope groove (21) in the length direction have rounded corners between them and the side of the pad (2).

7. The novel pad structure for suppressing corona at the end of a generator stator winding according to claim 5, characterized in that, The distance between the far end of the docking block (3) that is vertically connected to the first surface (32) and the first surface (32) is greater than the fillet (11) of the wire rod.

8. The novel pad structure for suppressing corona at the end of a generator stator winding according to claim 5, characterized in that, The distance between the far end of the docking block (3) that is perpendicularly connected to the first surface (32) and the first surface (32) is equal to the fillet (11) of the wire rod.

9. The novel pad structure for suppressing corona at the ends of generator stator windings according to claim 7 or 8, characterized in that, The outer surface of the two connecting blocks (3) at one end of the pad (2) is the third surface (34). The connecting block (3) has a rounded corner (35) on the third surface (34). The first binding rope is vertically bound and fixed along the third surface (34) and the two wire rods (1) after being dipped in glue. The second binding rope is horizontally bound and fixed along the binding rope groove (21) and the first binding rope after being dipped in glue.

10. The novel pad structure for suppressing corona at the end of a generator stator winding according to claim 1, characterized in that, A felt impregnated with resin is provided between the contact surfaces of the pad (2) and the wire rod (1).

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