Mixed use method and mixed use structure of stator bars with different anti-corona layer structures and new stator bar

Abstract

The invention discloses a mixed use method and mixed use structure of stator bars with different anti-corona layer structures and a new stator bar, a better'reconstruction 'effect can be achieved through mixed use of the stator bars with different anti-corona layer structures in the same number, and an optimal mixed use method can be obtained through simulation and comparison, so that the stability of the stator bars with different anti-corona layer structures is improved. The condition of potential concentration is greatly improved, and the problem of insulation damage of the stator bar due to potential concentration can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of large hydro-generator, in particular to a mixed use method and structure of stator bars with different anti-corona layer structures and a new stator bar. BACKGROUND

[0002] The rated voltage level of large hydro-generators is continuously increasing, and the single machine capacity is continuously increasing, which puts higher requirements on the overall insulation system of the motor. The end of the stator bar of the motor has a very concentrated electric field distribution, which is the most likely place to produce partial discharge, and the insulation problem of the stator bar is one of the main reasons for motor damage. The end of the stator bar of the high-voltage generator is often the most concentrated electric field due to its special structure. When the electric field intensity in the local area exceeds the air voltage corona critical value, strong corona will occur, accompanied by temperature rise, and corona will also produce ozone, nitrogen monoxide, nitrogen dioxide and other gases, which will form strong corrosive substances after combining with water in the air, causing damage to the motor insulation material, and in severe cases, short circuit or open circuit of the motor will occur, causing fire and other safety problems. In order to improve this situation, in actual engineering, a layer of semi-conductive anti-corona layer is usually applied to the end of the stator bar of the generator to homogenize the electric field at the end of the stator bar, thereby ensuring the safety and reliability of the hydro-generator during operation.

[0003] Traditional stator bar anti-corona layer structures, such as semi-conductor anti-corona layer or resistance type anti-corona layer, may have performance degradation or high-temperature ablation problems when dealing with high-temperature and high-voltage environments. On the one hand, high-temperature environments can accelerate the aging process of anti-corona layer materials, causing changes in their resistivity and affecting the anti-corona effect. On the other hand, high-voltage environments can cause breakdown or discharge of anti-corona layer materials, leading to high-temperature ablation. These problems not only reduce the operating efficiency of the generator, but also can cause serious safety accidents.

[0004] In general use, the stator bars of the same layer are usually of the same type, and there is a situation of potential concentration at the end position during use. Simply mixing stator bars with different anti-corona layer structures, the electric field is still concentrated after "reconstruction" under the action of the connecting piece, leaving a safety hazard, and there is a lack of corresponding methods and structures. SUMMARY

[0005] This invention provides a method, structure, and new stator bars for mixing stator bars with different anti-corona layer structures. It aims to solve the problems mentioned above, such as the safety risks and limited anti-corona effect of the existing stator bars' anti-corona layers in high-temperature and high-voltage environments, the potential concentration of stator bars of the same type, and the fact that the potential concentration still exists after the electric field is "reconstructed" by the connectors when stator bars with different anti-corona layer structures are simply mixed, leaving potential safety hazards. There is also a lack of corresponding mixing methods and structures.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for mixing stator bars with different anti-corona layer structures includes the following steps: Material selection: Traditional stator bars and new stator bars with different anti-corona layer structures are selected. The resistivity of the anti-corona layer of the new stator bars is greater than that of the anti-corona layer of the traditional stator bars. Grouping: Select a number of traditional stator bars and new stator bars and arrange them alternately in the same layer in different ways to form a number of mixed units. The total number of stator bars in each mixed unit is the same. Simulation analysis: First, the potential distribution diagrams of the traditional stator bars and the new stator bars were obtained separately by simulation software. Then, the potential distribution diagrams of each group of mixed units were obtained by simulation software. Determine the optimal mixing method: By comparing the potential distribution diagram of each group of mixed units with the potential distribution diagrams of individual traditional stator bars and new stator bars to determine the potential concentration, the arrangement of the mixed units corresponding to the potential distribution diagram that most significantly improves the potential concentration of the stator bars is selected as the optimal mixing method. Installation: The stator bars are installed sequentially according to the optimal mixed-use arrangement.

[0007] Preferably, the grouping step includes the following conditions: the number of traditional stator bars and the number of new stator bars are the same, and the total number of stator bars in the mixed unit is at least four.

[0008] Preferably, the simulation analysis uses COMSOL software, and the parameters include: the conductivity and arrangement structure of each anti-corona layer of the traditional stator bar and the new stator bar of the mixed unit are imported respectively; To establish the electric field boundary conditions for the stator bars in the mixed unit, select the conductor located inside, set the display selection to adjacent selection, add the boundary condition "electric potential" in the current physical field, and select and set the voltage of the outer surface part of the conductor to 25300V. Select the low-resistance component located on the outside, set the display selection to adjacent selection, add the boundary condition "grounded" in the current physical field, and select and set the outer surface portion of the low-resistance component. Set the frequency to 50Hz in the "Research" section.

[0009] A mixed structure of stator bars with different anti-corona layer structures is obtained by the above-mentioned method of mixing stator bars with different anti-corona layer structures. The mixed structure is divided into multiple mixed units around the axis. The stator bars in each mixed unit are located in the same layer. The number of traditional stator bars and the number of new stator bars in each mixed unit are the same. The traditional stator bars and new stator bars are arranged alternately in each mixed unit. Adjacent stator bars are connected by connectors.

[0010] Preferably, the mixed-use unit contains at least four stator bars, two of which are traditional stator bars and two of which are new stator bars.

[0011] More preferably, the conventional stator bar includes: Conductor A has a groove region and an end region connected sequentially along the extension direction of conductor A; The first main insulating layer A covers the groove region of conductor A and extends to the starting position of the first corner of the end region; The first anti-corona layer A covers the position corresponding to the groove region of the first main insulating layer A and the position corresponding to the end region adjacent to the groove region; The second anti-corona layer A has one end overlapping the portion of the first anti-corona layer A away from the groove area, and the other end wrapped around the first main insulating layer A. The third anti-corona layer A has one end overlapping the part of the first anti-corona layer A away from the groove area, and the other end wrapping around the first main insulation layer A, and the third anti-corona layer A completely wraps around the second anti-corona layer A; The second main insulation layer A completely covers the first anti-corona layer A, the second anti-corona layer A and the third anti-corona layer A; The resistance values ​​of the first main insulation layer A, the first anti-corona layer A, the second anti-corona layer A, the third anti-corona layer A, and the second main insulation layer A increase sequentially.

[0012] A novel stator bar, used in conjunction with conventional stator bars to form a hybrid structure of stator bars with different anti-corona layer structures as described above, includes: Conductor B has a groove region and an end region connected sequentially along the extension direction of conductor B; The main insulation layer B covers the surface of conductor B; The first anti-corona structure includes a first anti-corona layer B, which covers the main insulating layer B at the position corresponding to the groove area. The second anti-corona mechanism is covered at the position corresponding to the end area of ​​the main insulation layer B. The resistivity of the second anti-corona mechanism is greater than that of the first anti-corona structure. The second anti-corona mechanism includes an inner shielding layer, a middle shielding layer, and an outer shielding layer that are sequentially overlapped and have increasing resistivity. The inner shielding layer overlaps the edge portion of the first anti-corona structure, the middle shielding layer overlaps the edge portion of the inner shielding layer, and the outer shielding layer overlaps the edge portion of the first anti-corona structure and wraps around the middle shielding layer and the outer shielding layer.

[0013] Preferably, the inner shielding layer includes a second anti-corona layer B, a third anti-corona layer B, and a fourth anti-corona layer B that are sequentially overlapped along the extension direction of conductor B, with the second anti-corona layer B overlapping the first anti-corona layer B.

[0014] More preferably, the central shielding layer includes a fifth insulating layer B and a sixth insulating layer B sequentially overlapping each other along the extension direction of conductor B. The fifth insulating layer B wraps around the fourth anti-corona layer B. One end of the sixth insulating layer B overlaps the edge portion of the fourth anti-corona layer B away from the third anti-corona layer B. The other end of the sixth insulating layer B wraps around the main insulating layer B. The sixth insulating layer B simultaneously covers the edge portions of the fourth anti-corona layer B and the edge portions of the fifth insulating layer B.

[0015] Furthermore, the outer shielding layer includes a second insulating layer B and a seventh anti-corona layer B. The second insulating layer B wraps around the first anti-corona layer B, the inner shielding layer, and the middle shielding layer, and the seventh anti-corona layer B wraps around the second insulating layer B. The resistance values ​​of the main insulating layer B, the first anti-corona layer B, the second anti-corona layer B, the third anti-corona layer B, the fourth anti-corona layer B, the fifth insulating layer B, the sixth insulating layer B, the second insulating layer B, and the seventh anti-corona layer B increase sequentially.

[0016] The beneficial effects of this invention are: 1. A mixed-use method is provided, which can select the best mixed-use method with the best improvement effect through simulation and comparison for stator bars with different anti-corona layer structures; 2. A hybrid structure is provided. By introducing stator bars with different anti-corona layer structures, the outstanding problems of performance degradation and high-temperature erosion caused by local electric field concentration in the anti-corona layer structure of traditional stator bars are solved. Although the new stator bar alone has a certain improvement effect, the combination of traditional stator bars and new stator bars will achieve a more obvious improvement effect, aiming to significantly improve the anti-corona performance and durability of stator bars. 3. This invention provides a specific stator bar structure for mixed applications. Compared with traditional stator bars, it ensures the stable operation of the generator. By stacking a first anti-corona structure, an inner shielding layer, a middle shielding layer, and an outer shielding layer in the overlapping area, this invention can improve the current carrying capacity of the overlapping area and homogenize the electric field at the end of the stator bars, thereby ensuring the safety and reliability of the hydro-generator during operation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the cross-section of a conventional stator bar according to the present invention; Figure 2 This is a schematic diagram of a three-dimensional model of the end and slot of a conventional stator bar according to the present invention; Figure 3 This is a schematic diagram of the cross-section of the new stator bar of the present invention; Figure 4 This is a schematic diagram of a three-dimensional model of the end and groove of the new stator bar of the present invention; Figure 5 The diagram shows the potential distribution of the conventional stator bar and the new stator bar of this invention. Figure 6 This is a charge flow diagram illustrating the transition from the conventional stator bar to the new stator bar according to the present invention. Figure 7 This is a diagram showing the current flow direction of the conventional stator bars and the new stator bars of the present invention connected by a connector; Figure 8 This is a schematic diagram of a mixed use of traditional stator bars and new stator bars, in the order of traditional stator bars - traditional stator bars - new stator bars - new stator bars; Figure 9 This is a potential distribution diagram of Embodiment 9 of the present invention; Figure 10 This is a potential distribution diagram of Embodiment 10 of the present invention; Figure 11 This is a potential distribution diagram of Embodiment 11 of the present invention; Figure 12 This is a potential distribution diagram of Embodiment 12 of the present invention; Figure 13 This is a potential distribution diagram of Embodiment 13 of the present invention; In the diagram: 1. First main insulation layer A; 2. First anti-corona layer A; 3. Second anti-corona layer A; 4. Third anti-corona layer A; 5. Second main insulation layer A; 6. Main insulation layer B; 7. First anti-corona layer B; 8. Second anti-corona layer B; 9. Third anti-corona layer B; 10. Fourth anti-corona layer B; 11. Fifth insulation layer B; 12. Sixth insulation layer B; 13. Second insulation layer B; 14. Seventh anti-corona layer B. Detailed Implementation

[0018] The embodiments will be further described below with reference to the accompanying drawings.

[0019] Example 1: A method for mixing stator bars with different anti-corona layer structures includes the following steps: Material selection: Traditional stator bars and new stator bars with different anti-corona layer structures are selected. The resistivity of the anti-corona layer of the new stator bars is greater than that of the anti-corona layer of the traditional stator bars. Grouping: Select a number of traditional stator bars and new stator bars and arrange them alternately in the same layer in different ways to form a number of mixed units. The total number of stator bars in each mixed unit is the same. Simulation analysis: First, the potential distribution diagrams of the traditional stator bars and the new stator bars were obtained separately by simulation software. Then, the potential distribution diagrams of each group of mixed units were obtained by simulation software. Determine the optimal mixing method: By comparing the potential distribution diagram of each group of mixed units with the potential distribution diagrams of individual traditional stator bars and new stator bars to determine the potential concentration, the arrangement of the mixed units corresponding to the potential distribution diagram that most significantly improves the potential concentration of the stator bars is selected as the optimal mixing method. Installation: The stator bars are installed sequentially according to the optimal mixed-use arrangement.

[0020] Example 2: Both traditional and new stator bars generate localized electric field concentrations. In these concentrated areas, the traditional stator bar's concentration is more pronounced, making it more susceptible to insulation damage due to excessively high electric field strength, which in turn damages the motor. The main difference between the two structures lies in the role of the new stator bar's fourth anti-corona layer B10 and fifth insulation layer B11, which "reconstruct" the electric field distribution.

[0021] like Figure 5 As shown, the bending structure of the stator bar will cause the nearby electric lines to be twisted and dense (edge ​​effect). The electric field concentration occurs in the second anti-corona layer II of the traditional stator bar. By adding four layers of anti-corona layers with higher resistivity on the basis of the second anti-corona layer, a nonlinear conductive path is formed under high voltage. While maintaining the characteristics of the main insulation capacitor, a small amount of leakage current is allowed to flow. At the same time, the "resistance-capacitance" synergistic voltage equalization is achieved through multiple high-resistance anti-corona layers.

[0022] Although the innovative bar has a larger concentration area and a lower electric field strength, its rising frequency in this area is relatively high, posing a significant risk of excessively high electric field strength.

[0023] Based on the relationship between the electric field distribution of a single stator bar and the bar structure, it can be inferred that electric field "reconstruction" can also occur when two different types of bars are connected by connectors, such as... Figure 6 and Figure 7 As shown, the top is the new stator bar, and the bottom is the traditional stator bar. The charge on the two types of bars will move across the bars through the connector.

[0024] In addition, by combining the trend analysis of the electric field distribution of the two types of stator bars, and in order to improve the hidden dangers of the two types of stator bars (the hidden dangers caused by the small local area of ​​the electric field of the traditional stator bar and the hidden dangers caused by the slightly higher rising frequency of the new stator bar), and to have a better "reconstruction" effect, the number of the two types of bars must be consistent. The stator bars can only be achieved simultaneously by using connectors.

[0025] Example 3: A three-dimensional model of a traditional stator bar is created based on its actual dimensions, and simulation is performed in COMSOL software.

[0026] Furthermore, the conductivity and arrangement structure of each anti-corona layer of the traditional stator bar and the new stator bar of the mixed unit are respectively introduced; Furthermore, the electric field boundary conditions of the model are established for the four stator bars, including: Select the conductor located inside, set the display selection to adjacent selection, add the boundary condition "potential" in the current physics field, and select and set the voltage of the outer surface of the conductor to 25300V. Select the low-resistance component located on the outside, set the display selection to adjacent selection, add the boundary condition "grounded" in the current physical field, and select and set the outer surface portion of the low-resistance component.

[0027] Set the frequency to 50Hz in the "Research" section.

[0028] The waveforms of the individual simulation results for the traditional stator bars and the new stator bars are shown below. Figure 5 As shown.

[0029] Example 4: A mixed structure of stator bars with different anti-corona layer structures is obtained by the above-mentioned method of mixing stator bars with different anti-corona layer structures. The mixed structure is divided into multiple mixed units around the axis. The stator bars in each mixed unit are located in the same layer. The number of traditional stator bars and the number of new stator bars in each mixed unit are the same. The traditional stator bars and new stator bars are arranged alternately in each mixed unit. Adjacent stator bars are connected by connectors.

[0030] like Figure 1 and Figure 2 As shown, the conventional stator bar includes: Conductor A has a groove region and an end region connected sequentially along the extension direction of conductor A; The first main insulating layer A1 covers the groove region of conductor A and extends to the starting position of the first corner of the end region; The first anti-corona layer A2 covers the first main insulating layer A1 at the position corresponding to the groove region and at the position corresponding to the end region adjacent to the groove region; The second anti-corona layer A3 has one end overlapping the portion of the first anti-corona layer A2 away from the groove area, and the other end wrapped around the first main insulating layer A1. The third anti-corona layer A4 has one end overlapping the part of the first anti-corona layer A2 away from the groove area, and the other end wrapping around the first main insulation layer A1, and the third anti-corona layer A4 completely wraps around the second anti-corona layer A3. The second main insulation layer A5 completely covers the first anti-corona layer A2, the second anti-corona layer A3 and the third anti-corona layer A4; The resistance values ​​of the first main insulating layer A1, the first anti-corona layer A2, the second anti-corona layer A3, the third anti-corona layer A4, and the second main insulating layer A5 increase sequentially.

[0031] Example 5: The first anti-corona layer A2 and the second anti-corona layer A3 of the traditional stator bar overlap to form an anti-corona structure.

[0032] The traditional stator bar has a third anti-corona layer A4 and a second anti-corona layer A3 overlapping to form an anti-corona structure.

[0033] The first main insulation layer A1 of the traditional stator bar completely covers the stator core slot bar and extends to the starting position of the first corner at the end of the bar.

[0034] In traditional stator bars, the resistance of the first anti-corona layer A2 is less than that of the second anti-corona layer A3, and the resistance of the second anti-corona layer A3 is less than that of the third anti-corona layer A3.

[0035] The second and third anti-corona layers A3 of the traditional stator bar are both nonlinear anti-corona materials.

[0036] The simulation was performed using the method described above, and the simulation waveform is shown below. Figure 5 As shown on the left.

[0037] Example 6: like Figure 3 and Figure 4 As shown, the new stator bar structure includes bar conductor B, main insulation layer B6, second insulation layer B13, first anti-corona layer B7, second anti-corona layer B8, third anti-corona layer B9, fourth anti-corona layer B10, fifth insulation layer B11, sixth insulation layer B12 and seventh anti-corona layer B14.

[0038] The main insulation layer B6 of the new stator bar completely covers the conductor B of the bar. The first anti-corona layer B7, the second anti-corona layer B8, the third anti-corona layer B9, the fourth anti-corona layer B10, the fifth insulation layer B11, the sixth insulation layer B12 and the seventh anti-corona layer B14 are applied to the main insulation layer B6.

[0039] The first anti-corona layer B7 and the second anti-corona layer B8 overlap to form a first-second overlap area; the second anti-corona layer B8 and the third anti-corona layer B9 overlap to form a second-third overlap area; the third anti-corona layer B9 and the fourth anti-corona layer B10 overlap to form a third-fourth anti-corona area; the fourth anti-corona layer B10 and the fifth insulation layer B11 overlap to form a fourth-fifth anti-corona area; and the fifth insulation layer B11 and the sixth anti-corona layer V overlap to form a fifth-sixth anti-corona area. Except for the third-fourth anti-corona area, which has an overlap length of 10mm, the length of all other overlap areas is 20mm.

[0040] Example 7: The new stator bar's first anti-corona layer B7 covers the stator slot bar and extends towards the end to the first corner position.

[0041] The new stator bar's second anti-corona layer B8 covers the end of the first anti-corona layer B7 by 20mm and extends 100mm towards the end.

[0042] The new stator bar's third anti-corona layer B9 covers the end of the second anti-corona layer B8 by 20mm and extends 120mm towards the end.

[0043] The new stator bar's fourth anti-corona layer B10 covers the end of the third anti-corona layer B9 by 20mm and extends 170mm towards the end.

[0044] The fifth insulation layer B11 of the new stator bar is fully overlapped with the end of the fourth anti-corona layer B10 by 40mm.

[0045] The sixth insulation layer B12 of the new stator bar covers the end of the fifth insulation layer B11 by 20mm and extends 70mm towards the end.

[0046] Example 8: The resistance of the first anti-corona layer B7 of the new stator bar is less than that of the second anti-corona layer B8, the resistance of the second anti-corona layer B8 is less than that of the third anti-corona layer B9, the resistance of the third anti-corona layer B9 is less than that of the fourth anti-corona layer B10, the resistance of the fourth anti-corona layer B10 is less than that of the fifth anti-corona layer B11, the resistance of the fifth anti-corona layer B11 is less than that of the sixth anti-corona layer B12, and the resistance of the sixth anti-corona layer B12 is less than that of the seventh anti-corona layer B13.

[0047] The second anti-corona layer B8, the third anti-corona layer B9, the fourth anti-corona layer B10, the fifth insulation layer B11, the sixth insulation layer B12, and the seventh anti-corona layer B14 of the new stator bar are all nonlinear anti-corona materials.

[0048] The second insulation layer B13 of the new stator bar covers the first anti-corona layer B7, the second anti-corona layer B8, the third anti-corona layer B9, the fourth anti-corona layer B10, the fifth insulation layer B11, and the sixth insulation layer B12, with the coverage area extending from 10mm before the first-second overlap area to 20mm after the fourth anti-corona layer.

[0049] The seventh anti-corona layer of the new stator bar is on the second insulation layer B13, and the coverage area extends from the starting point of the first corner at the end of the bar to the starting point of the second corner at the end of the bar.

[0050] The new stator bars were simulated, and the simulation steps and boundary conditions were the same as those for the traditional stator bars. The simulation results waveforms are shown below. Figure 5 The waveform on the right is shown.

[0051] Example 9: Traditional stator bars and new stator bars are arranged in a mixed manner. Figure 8 Upper layer bar 1 is a traditional stator bar, upper layer bar 2 is a traditional stator bar, upper layer bar 3 is a new stator bar, and upper layer bar 4 is a new stator bar. Figure 9 The diagram shows the potential distribution of the four wires. The highest potential points of the four wires are 25538V, 25314V, 27182V, and 26982V, respectively.

[0052] Example 10: Traditional stator bars and new stator bars are arranged in a mixed manner. Upper layer bar 1 is a new stator bar, upper layer bar 2 is a new stator bar, upper layer bar 3 is a traditional stator bar, and upper layer bar 4 is a traditional stator bar. Figure 10 The diagram shows the potential distribution of the four wires. The highest potential points of the four wires are 27225V, 26929V, 26673V, and 27013V, respectively.

[0053] Example 11: Traditional stator bars and new stator bars are arranged in a mixed manner. Upper layer bar 1 is a new stator bar, upper layer bar 2 is a traditional stator bar, upper layer bar 3 is a traditional stator bar, and upper layer bar 4 is a new stator bar. Figure 11 The diagram shows the potential distribution of the four wires. The highest potential points of the four wires are 27210V, 27105V, 27128V, and 27118V, respectively.

[0054] Example 12: Traditional stator bars and new stator bars are arranged in a mixed manner. Upper layer bar 1 is a traditional stator bar, upper layer bar 2 and upper layer bar 3 are new stator bars, and upper layer bar 4 is a traditional stator bar. Figure 12 The diagram shows the potential distribution of the four wires. The highest potential points of the four wires are 27957V, 27158V, 26903V, and 26745V, respectively.

[0055] Example 13: Traditional stator bars and new stator bars are arranged in a mixed manner. Upper layer bar 1 is a traditional stator bar, upper layer bar 2 is a new stator bar, upper layer bar 3 is a traditional stator bar, and upper layer bar 4 is a new stator bar. Figure 13The diagram shows the potential distribution of the four wires. The highest potential points of the four wires are 27896V, 27085V, 26702V, and 26978V, respectively.

[0056] Example 14: Will Figure 9~Figure 13 and Figure 5 In comparison, among the five mixed stator bar arrangements, the upper layer bar 1 is a traditional stator bar, the upper layer bar 2 is a traditional stator bar, the upper layer bar 3 is a new stator bar, and the upper layer bar 4 is a new stator bar. That is, the mixed structure of Example 1 is the best. This arrangement significantly improves the concentration of potential in the stator bars. The potential concentration, i.e., the protruding part, is greatly reduced or even flattened, and the rate of change is also greatly reduced. The traditional stator bar can be improved by up to 8%, and the new stator bar can be improved by up to 3%. This can effectively reduce the problem of insulation damage caused by potential concentration in the stator bars.

Claims

1. A method for mixing stator bars with different anti-corona layer structures, characterized in that, Includes the following steps: Material selection: Traditional stator bars and new stator bars with different anti-corona layer structures are selected. The resistivity of the anti-corona layer of the new stator bars is greater than that of the anti-corona layer of the traditional stator bars. Grouping: Select a number of traditional stator bars and new stator bars and arrange them alternately in the same layer in different ways to form a number of mixed units. The total number of stator bars in each mixed unit is the same. Simulation analysis: First, the potential distribution diagrams of the traditional stator bars and the new stator bars were obtained separately by simulation software. Then, the potential distribution diagrams of each group of mixed units were obtained by simulation software. Determine the optimal mixing method: By comparing the potential distribution diagram of each group of mixed units with the potential distribution diagrams of individual traditional stator bars and new stator bars to determine the potential concentration, the arrangement of the mixed units corresponding to the potential distribution diagram that most significantly improves the potential concentration of the stator bars is selected as the optimal mixing method. Installation: The stator bars are installed sequentially according to the optimal mixed-use arrangement.

2. The method for mixing stator bars with different anti-corona layer structures according to claim 1, characterized in that, The grouping step includes the following conditions: the number of traditional stator bars and the number of new stator bars are the same, and the total number of stator bars in the mixed unit is at least four.

3. The method for mixing stator bars with different anti-corona layer structures according to claim 1, characterized in that, The simulation analysis used COMSOL software, and the parameters included: the conductivity and arrangement structure of each anti-corona layer of the traditional stator bar and the new stator bar of the mixed unit were imported respectively. To establish the electric field boundary conditions for the stator bars in the mixed unit, select the conductor located inside, set the display selection to adjacent selection, add the boundary condition "electric potential" in the current physical field, and select and set the voltage of the outer surface of the conductor to 25300V. Select the low-resistance component located on the outside, set the display selection to adjacent selection, add the boundary condition "grounded" in the current physical field, and select and set the outer surface portion of the low-resistance component. Set the frequency to 50Hz in "Research".

4. A mixed structure for stator bars with different anti-corona layer structures, characterized in that, The mixed structure obtained by the method of mixing stator bars with different anti-corona layer structures as described in any one of claims 1 to 3 is divided into multiple mixed units around the axis. The stator bars of each mixed unit are located in the same layer. The number of traditional stator bars and the number of new stator bars in each mixed unit are the same. The traditional stator bars and new stator bars are arranged alternately in each mixed unit. Adjacent stator bars are connected by connectors.

5. The mixed structure of stator bars with different anti-corona layer structures according to claim 4, characterized in that, The mixed-use unit contains at least four stator bars, two of which are traditional stator bars and two of which are new stator bars.

6. The mixed structure of stator bars with different anti-corona layer structures according to claim 5, characterized in that, The conventional stator bars include: Conductor A has a groove region and an end region connected sequentially along the extension direction of conductor A; The first main insulating layer A (1) covers the groove region of conductor A and extends to the starting position of the first corner of the end region; The first anti-corona layer A (2) covers the position corresponding to the groove area of ​​the first main insulating layer A (1) and the position corresponding to the end area adjacent to the groove area; The second anti-corona layer A (3) overlaps one end of the first anti-corona layer A (2) on the part away from the groove area, and the other end is wrapped around the first main insulating layer A (1); The third anti-corona layer A (4) overlaps one end of the first anti-corona layer A (2) on the part away from the groove area, and the other end is wrapped around the first main insulation layer A (1), and the third anti-corona layer A (4) completely wraps the second anti-corona layer A (3). The second main insulation layer A (5) completely covers the first anti-corona layer A (2), the second anti-corona layer A (3) and the third anti-corona layer A (4); The resistance values ​​of the first main insulation layer A (1), the first anti-corona layer A (2), the second anti-corona layer A (3), the third anti-corona layer A (4), and the second main insulation layer A (5) increase sequentially.

7. A novel stator bar, characterized in that, A hybrid structure for use with conventional stator bars to form a stator bar with a different anti-corona layer structure as described in claim 6, comprising: Conductor B has a groove region and an end region connected sequentially along the extension direction of conductor B; The main insulating layer B (6) covers the surface of conductor B; The first anti-corona structure includes a first anti-corona layer B (7), which covers the main insulating layer B (6) at the position corresponding to the groove area; The second anti-corona mechanism is covered on the position corresponding to the end region of the main insulation layer B (6). The resistivity of the second anti-corona mechanism is greater than that of the first anti-corona structure. The second anti-corona mechanism includes an inner shielding layer, a middle shielding layer, and an outer shielding layer that are sequentially overlapped and have increasing resistivity. The inner shielding layer overlaps the edge portion of the first anti-corona structure, the middle shielding layer overlaps the edge portion of the inner shielding layer, and the outer shielding layer overlaps the edge portion of the first anti-corona structure and wraps around the middle shielding layer and the outer shielding layer.

8. A novel stator bar according to claim 7, characterized in that, The inner shielding layer includes a second anti-corona layer B (8), a third anti-corona layer B (9) and a fourth anti-corona layer B (10) that are sequentially overlapped along the extension direction of conductor B, with the second anti-corona layer B (8) overlapping the first anti-corona layer B (7).

9. A novel stator bar according to claim 8, characterized in that, The central shielding layer includes a fifth insulating layer B (11) and a sixth insulating layer B (12) sequentially overlapping along the extension direction of conductor B. The fifth insulating layer B (11) wraps around the fourth anti-corona layer B (10). One end of the sixth insulating layer B (12) overlaps the edge portion of the fourth anti-corona layer B (10) away from the third anti-corona layer B (9). The other end of the sixth insulating layer B (12) wraps around the main insulating layer B (6). The sixth insulating layer B (12) simultaneously covers the edge portion of the fourth anti-corona layer B (10) and the edge portion of the fifth insulating layer B (11).

10. A novel stator bar according to claim 9, characterized in that, The outer shielding layer includes a second insulating layer B (13) and a seventh anti-corona layer B (14). The second insulating layer B (13) wraps the first anti-corona layer B (7), the inner shielding layer and the middle shielding layer. The seventh anti-corona layer B (14) wraps the second insulating layer B (13). The resistance values ​​of the main insulating layer B (6), the first anti-corona layer B (7), the second anti-corona layer B (8), the third anti-corona layer B (9), the fourth anti-corona layer B (10), the fifth insulating layer B (11), the sixth insulating layer B (12), the second insulating layer B (13), and the seventh anti-corona layer B (14) increase sequentially.

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