JPH044816B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a cylindrical directly cooled rotor field winding in a turbine generator or the like, and particularly to the relative relationship between the field windings that occurs during operation of these devices. The present invention relates to a field winding suitable for preventing wear of the field winding due to movement.

[Background of the invention]

Large-scale generators require extensive cooling, so the stator is constantly cooled using water or other fluids, and the rotor is usually cooled using hydrogen gas. It is. Here, a typical structure of a rotor of a turbine generator will be explained. As shown in FIG. 1, the rotor 1 has a cylindrical rotor core 30, and the rotor field winding 3 is housed in a longitudinal slot 31 provided along the outer periphery of the rotor core. The field winding consists of a conductor that is first placed at the bottom in a pair of slots closest to the pole faces and then passed through the next winding until it reaches a position near the top of the slot. The wire layers are stacked in a spiral. One stacked winding is shown in FIG. Winding stacking then continues in a similar manner in the next pair of rotor slots, thus repeatedly winding the windings for the desired number of slot pairs. Current flow through these windings follows a conductive path similar to the winding stacking order described above.

Since the conductors are specifically flat conductor rods in the shells, an insulating layer is placed between adjacent shells in the slots to keep the rotor pole windings wound in series. has been done.

Also, to explain cooling, first, the conductor inside the slot is cooled by holes in the thickness direction of the conductor rod and holes extending along its longitudinal direction, and the holes provided in each conductor rod are adjacent to each other. This is done by forming suitable cooling passages in alignment with holes provided in the conductor rods, and by flowing a coolant through these cooling passages.

On the other hand, for cooling the slot outside area (winding end) of the rotor winding, copper conductor rods connected in parallel to the rotor field winding are used, and each conductor rod is provided with a groove. By matching them together, a cooling passage is formed.

The conductor rods of these windings are connected in parallel by brazing at the winding corner portions outside each slot. There is no need to insert insulating material between the conductor bars connected in parallel in this way. However, it has recently been noted that when windings are configured in this way, copper wear problems can occur. That is, copper particles accumulate due to mechanical wear between these parallel connected copper layers. For clarity, the term "layer" as used in this specification refers to the series connected pole winding sections. Also, the term "laminar" shall refer to adjacent parallel connected conductive winding sections. A layer is therefore composed of one or more thin layers. It is these laminae that can contain longitudinally extending cooling passages.

During normal operation of the generator at relatively high speeds, no significant movement appears between adjacent laminae. The reason for this is thought to be that a large centrifugal force is generated to hold the conductor rods of the rotor in a substantially constant position. However, in some cases, this generator does not generate electrical power and the speed of the rotor is maintained by moving the machine with a turning device to prevent deflection or deformation of the rotor body. . It is believed that this low speed operation causes relative movement of adjacent laminae connected in parallel. Since there is no electrically insulating material inserted between these laminae, the laminae are in mechanical contact along the length of the rotor slot, and therefore due to the relative movement between the laminae, the copper Wear of the material may occur. This wear can cause copper particles to accumulate, which can result in ground fault problems in the rotor winding circuit.

In order to prevent the wear of copper between thin layers, the published patent
No. 57-75543 ``Rotor of an electrical machine with mechanical separator'' is submitted, which provides between the thin layers an anti-wear material consisting of a polyester material reinforced with glass fibers.

However, in this case, the height of the winding in the slot depth direction increases, so it is necessary to increase the slot depth. This results in preventing the generator from becoming smaller. In addition, Fig. 3 shows the anti-wear material 22.
The figure shows the winding structure at the slot end when
In this case, in a high-speed rotating machine (3000 or 3600 rpm) such as a turbine generator, a very large centrifugal force acts during operation, and the compressive force due to this centrifugal force is concentrated on the anti-wear material. Therefore, the surface pressure applied to the anti-wear material is approximately the same as the surface pressure applied to the interlayer insulation material.
Since it reaches more than 1.5 times, there is concern that the anti-wear material may be damaged.

[Purpose of the invention]

It is an object of the present invention to provide a novel rotor field winding that prevents copper wear between adjacent parallel connected laminae of the rotor winding and has a long life.

[Summary of the invention]

During operation in the straight sections of the rotor field windings of turbine generators, copper powder can accumulate due to mechanical wear between the laminae, resulting in ground faults or interlaminar shorts. In order to prevent these drawbacks, the present invention provides a rotor field winding in which at least two conductive thin layers, which are formed by dividing a part of a laminated conductive winding, are joined at a joint surface. In the rotor field winding constituting the conductive winding, the conductive winding joins at least a part of the joint surface between the conductive thin layers divided in the same direction as the lamination direction of the conductive winding. The purpose is to provide a joint.

As a result, in response to a circumferential force on the rotor field winding, or a force perpendicular to the stacking direction, the sliding or horizontal sliding between the conductive thin layers is limited at the joints. Therefore, it prevents mechanical wear, eliminates the generation of copper particles, and prevents ground faults or interlayer short circuits.

[Embodiments of the invention]

FIG. 4 illustrates a rotor of a turbine generator. The present invention can be applied to such a direct cooling machine. The rotor 1 has a substantially cylindrical iron core 3
has 0. A slot 31 is provided on the outer periphery of the iron core 30.
extends in the longitudinal direction. The windings of the magnetic poles 35 are arranged in slots a and a', b and b', c and c', and d and d'. The opposite pole windings are symmetrically placed in the other slots with the same twist. The layers of windings are arranged in slots a and a', b and b', c and c', d and d' and connected to form conductive paths.
The conductive path runs in layers from bottom to top of slots a, a', then from top to bottom of slots b, b', then from bottom to top of slots c, c', and finally from slots d, d. ′ from the top to the bottom. Slots d, d' constitute the last slots used for the winding of the pole 35 in the illustrated embodiment. A similar winding structure is used for the opposite pole. Because of the large currents and various electrical and magnetic heating effects that occur, direct cooling of the rotor windings is highly desirable for long-term reliable operation of the generator. For this purpose, matched ventilation holes are provided in the copper wire-wound conductor rods,
The rotor is placed in a sealed hydrogen atmosphere. Furthermore,
The surface of the rotor core is processed into a scoop shape 34. This process works so that the rotor pumps hydrogen through the holes in the wire-wound conductor rods as it rotates. Hydrogen gas is thus scooped into the scoop-like opening and forced out through the opening 33 to perform the desired cooling function. Because of the ventilation holes provided in the winding conductor rods, similar holes are provided in the insulating material within the slots so as not to obstruct this flow of cooling fluid.

FIG. 5 illustrates the invention in one rotor slot. The slots are between rotor teeth extending from rotor core 30. A copper conductor is indicated generally by reference numeral 42. As can be seen, a winding insulator 43 is provided between the winding layers.
The insulator 43 is provided with holes corresponding to those similarly provided in the copper conductor 42 to form cooling fluid passages 46. A plurality of winding layers, that is, 42 conductor layers and a winding insulator 43 are laminated.
As shown in FIG. 6, the conductor 42 is divided into a conductive thin layer 23 and a conductive thin layer 24 in the same direction as the stacking direction. A part of the joint surface where the conductive thin layer 23 and the conductive thin layer 24 are in contact with each other is joined by a solder joint 47, thereby making the two thin layers integral. Since this brazing is a partial brazing, it can be easily carried out, and the ease of assembling the winding is not impaired. This brazing prevents the formation of copper particles resulting from relative movement of the copper thin layer by inhibiting the relative movement.

Since it is also necessary to insulate the conductive windings 42 from the conductive rotor core, it is necessary to provide a slot insulation sheath 44, typically comprised of glass fiber reinforced epoxy resin. Similarly, an insulating clipage block 41 is used as shown to insulate the windings from the conductive wedge 32. The wedge 32 serves to retain the winding in the slot, particularly during normal high speed operation of the generator. These wedges 32 form dovetail fittings that follow the grooves 40 provided in the rotor teeth 6. Wedge 32 is typically made of steel or aluminum alloy.
The reason why such an alloy is required is that a large centrifugal force is applied to the wedge. The slots are preferably tapered to be narrower at the bottom so as to increase the strength of the rotor teeth 6, especially near their roots.

FIG. 6 shows one layer of the rotor winding. The winding section extending longitudinally within the slot has
Two physically and mechanically separate thin layers 23,2
There are 4. Each lamina is brazed at portion 50 as shown. , a cooling duct having openings 26 through which cooling fluid is forced under the action of the rotational motion of the rotor when arranged in back-to-back adjacent relationship as shown by using separate laminae. Each copper thin layer 2 is formed such that 25 is formed.
3, 24 can be machined with grooves. However, as mentioned above, a thin layer 2 is incorporated into the slot to prevent copper wear and copper particle build-up.
It can be seen that it is desirable that the parts 3 and 24 be joined with a certain pitch (in this example, they are joined by brazing). According to this method, the purpose can be achieved without increasing the slot depth. Also, due to the difference in thermal elongation due to the temperature difference between the thin layers, a shearing force is generated at the brazed portion at the corner of the field winding, but by joining them at a certain interval in the longitudinal direction of the slot, the temperature between the thin layers can be reduced. It can absorb the thermal elongation caused by the difference.

〔Effect of the invention〕

According to the present invention, the conductive layers obtained by dividing the wire-wound conductor rod 42 in the lamination direction are joined by brazing. As a result, the sliding that occurs between the conductive thin layers due to forces acting in a direction perpendicular to the stacking direction, that is, in the circumferential direction during low-speed operation, is prevented by brazing and no longer slides.
The generation of copper particles can be prevented. Therefore, it is possible to prevent ground faults or interlayer short circuit accidents that may occur in connection with this. Therefore, if this method is applied to something that requires time and money to repair, such as a large power generator, it will have a large economic effect, and will also have advantages such as being effective in preventing power outage accidents.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the turbine generator rotor;
The figure is a perspective view showing the field windings installed in a pair of rotor slots, Figure 3 is a diagram showing the slot end winding structure when anti-wear material is provided, and Figure 4 is the background of the present invention. FIG. 5 is a perspective view of the rotor illustrating the rotor slot; FIG. 5 is a cross-sectional view of the rotor slot showing the windings inserted therein in accordance with the present invention;
The figure shows an example of brazing between the thin layers of a pair of rotor conductor rods. 1... Rotor, 3... Field winding, 4... Field winding retaining ring, 12... Magnetic pole center, 13... Connection plate,
22... Anti-wear material, 23, 24... Thin layer, 25
...Cooling passage, 30...Rotor core, 31...Slot, 32...Wedge, 35...Magnetic pole, 40...
...Aisle, 41...Clippage block, 42...
Winding conductor rod, 43...Insulator, 44...Slot insulation, 46...Cooling passage, 47...With brazing, 50
...Tsuyome.

Claims (1)

[Claims] 1 A cylindrical core having a longitudinal slot along the outer periphery, and arranged in layers within this slot,
and a plurality of conductive windings connected in series,
The laminated layers of the plurality of conductive windings are connected in series by an electrical insulator placed between the laminated layers, and at least two layers are formed by dividing a part of the laminated conductive windings. In a rotor field winding in which the conductive winding is constructed by joining conductive thin layers at the joint surfaces, the conductive winding is made of conductive thin layers divided in the same direction as the lamination direction of the conductive windings. A rotor field winding for an electric machine, characterized in that a joint portion is provided that joins at least a part of a joint surface between layers.