JP2009131041A - Power-generator stator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power-generator stator that achieves reduction in field current and reduction in loss. <P>SOLUTION: The power-generator stator is configured such that a rotor 1 is placed at the center. The stator has a core 2. The core is provided with a plurality of coil slots 5 respectively extending along the axial center of a rotary shaft of the rotor so as to store each stator coil. The stator coil is composed of solid and hollow strand conductors that are directly or indirectly cooled by a refrigerant. The stator coil includes a half-turn coil comprising an upper coil 4a and a lower coil 4b mutually connected with each other at each end part protruding from both side faces of the stator core. The strand conductor is formed so as to be dislocated by being continuously twisted toward the extending direction of the coil slot at a part where the strand conductor is stored inside the coil slot. A proportionality coefficient α obtained by dividing the number of solid strands 4c constituting the half-turn coil by the number of hollow strands 4d is ≥2 while current density β of the stator coil is within a range of 8A/mm<SP>2</SP>≤β≤11A/mm<SP>2</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stator of a generator, and more particularly to a stator having a winding structure that is cooled using a refrigerant.

  In order to reduce the size of a generator, particularly a large-capacity generator, it is important to cool the stator coil and the rotor coil. There are various ways of cooling the generator coil. Particularly in a large-capacity generator, a large current flows through the stator coil, so that a high cooling capacity is required, and a method of directly cooling the coil with a refrigerant is adopted. The refrigerant flow path has a structure in which a space is provided in or adjacent to the strands constituting the stator coil, and is configured by mixing hollow strands or solid strands.

  On the other hand, a rotor coil in a large-capacity generator is housed in a slot arranged along the circumferential direction of the rotor core, and is held by inserting a rotor wedge into the upper portion of the slot. Cooled directly at. On the other hand, in-machine gas or a cooling medium supplied from the outside is used for the refrigerant of the stator coil.

  In addition, since the rotor is a rotor, the refrigerant supplied to the rotor and the rotor coil is limited. Generally, the in-machine gas is selected as a cooling medium for the rotor coil, and the large-capacity generator In many cases, the temperature of the rotor coil is a design constraint.

  In order to suppress the temperature rise of the rotor coil due to the field current, if the conductor cross-sectional area of the rotor coil is secured, the rotor diameter can be reduced due to restrictions such as rotor strength and magnetic path saturation, or by reducing the field current. As a result, the physique of the rotor is enlarged. In other words, how to suppress the temperature rise of the rotor coil is a problem in reducing the size of the generator.

As a direct countermeasure for the above-mentioned problems, a technique (for example, Patent Document 1 and Patent Document 2) that optimizes the ventilation shape of the rotor and the rotor coil and suppresses the temperature rise of the coil, and optimizes the slot shape of the rotor. A technique (for example, Patent Document 3) that reduces the field current and suppresses the temperature rise of the coil has been reported.
JP 2006-81367 A JP 2000-50576 Japanese Patent Laid-Open No. 11-355993

  In each of the disclosed examples of the above patent documents, the temperature is reduced by optimizing the rotor structure.

  However, the structural measures of the rotor alone are limited, and the cooling effect as a whole generator is not sufficient. Therefore, it is desired to reduce the field current and loss not only by measures for the rotor but also by cooling measures by the stator.

  The present invention has been made in consideration of the above-described points, and an object of the present invention is to provide a generator stator capable of reducing field current and loss.

To achieve the above object, the present invention provides:
A stator of a generator arranged concentrically with respect to a rotor via an air gap, the stator having an iron core so that the iron core follows the axis of the rotation axis of the rotor. A plurality of coil slots extending to store the stator coil are provided, and the stator coil is formed of solid and hollow wire conductors that are cooled directly or indirectly by a refrigerant, and the stator core A half-turn coil composed of an upper coil and a lower coil connected to each other at ends protruding from both side surfaces, wherein the wire conductor is a portion housed in the coil slot and extends from the coil slot. In the stator of the generator formed so as to be continuously twisted and shifted toward the current direction,
The proportionality coefficient α obtained by dividing the number of solid wires constituting the half-turn coil by the number of hollow wires is 2 or more, and the current density β of the coil is 8 A / mm ² ≦ β ≦ 11 A / mm ^{It is in} the range of ² .

  Since the present invention is configured so that the proportionality coefficient α and the current density β have predetermined values as described above, the temperature increase of the rotor winding due to the reduction of the field current is suppressed, and the generator efficiency is improved to achieve the same output. A generator with a small size can be obtained.

In the present invention, the configuration of the half-turn coil forming the stator coil housed in the stator slot shown in FIG. 1 is obtained by dividing the number of solid wires constituting the coil by the number of hollow wires. The proportionality coefficient α is 2 or more, and the current density β of the coil is in the range of 8 A / mm ² ≦ β ≦ 11 A / mm ² .

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Example 1)
FIG. 1 is an enlarged sectional view of a stator of a large-capacity generator according to a first embodiment of the present invention, and FIG. 2 shows a transverse section of the large-capacity generator according to the present invention. In FIG. 1, an upper coil 4a and a lower coil 4b are formed into half-turn coils by dividing a tortoiseshell-shaped coil into two at the coil end portion, and are inserted into the stator slot 5 with a spacer 14 between them. A ripple spring 12 is disposed on each coil side surface. In addition, the base plate 15 is inserted in the lower part of the lower coil 4b, and the stator wedge 7 is inserted in the upper part of the upper coil 4a, whereby the coils 4a and 4b are fixed in the slot 5.

  The upper coil 4a and the lower coil 4b are constituted by a solid wire 4c and a hollow wire 4d, which are not shown in the figure, with glass coating insulation, and the wires are continuously twisted along the rotational axis direction. Thus, typically, it is shifted by one and a half revolutions, that is, 540 degrees.

  The upper coil 4 a and the lower coil 4 b are appropriately adjusted in shape by the filler 11 and the separator 13, and the outer periphery thereof is insulated by the stator main insulating layer 6. In FIG. 1, the number of strands of the strands is two, but a configuration may be adopted in which the number of other rows is four, six, or the like.

  FIG. 2 shows a cross section of a rotating field generator. The generator includes a rotor 1 and a stator core 2, both of which are radially inward and outward with an air gap 3 therebetween. Are arranged concentrically. In the slot 5 of the stator core 2, an upper coil 4a and a lower coil 4b constituted by a solid element wire 4c and a hollow element wire 4d are inserted through a stator main insulating layer 6, and the inner diameter side of the stator Is held by a stator wedge 7 inserted into the.

  The rotor 1 is provided with a rotor slot 9 extending in the circumferential direction, and the field coil 8 housed in the rotor slot 9 is held by a rotor wedge 10 inserted on the rotor outer diameter side.

In the present embodiment, the cooling effect can be obtained by configuring the upper coil 4a and the lower coil 4b of the half-turn coil as follows. That is, the proportionality coefficient α = 2 obtained by dividing the number of the solid wires 4c constituting the upper coil 4a and the lower coil 4b by the number of the hollow wires 4d, and the current density β of the coils is a general value. According to the design example, the range is 8 A / mm ² ≦ β ≦ 11 A / mm ² . The proportionality coefficient α has a lower limit of 2, and the upper limit is naturally determined by constraints in designing the strands.

  The stator coil is composed of a solid wire 4c and a hollow wire 4d that are directly or indirectly cooled by a refrigerant, and is configured as an upper coil and a lower coil. And the half turn coils 4a and 4b comprised as an upper coil and a lower coil are mutually connected by the edge part which protruded from the both sides | surfaces of the stator core.

FIG. 3 shows the relationship between the current density β and the temperature rise value ΔTf of the field winding at the rated load when the 500 MVA class turbine generator is designed with α = 2. This is a result of evaluation by magnetic field analysis with the core outer shape and the wire configuration of the upper coil and the lower coil being the same and changing the number of wires. Thus, it can be seen that the temperature increase value ΔTf of the field winding is suppressed in the range of current density β ≧ 8 A / mm ² .

  This is because, by increasing the current density β, the slot size of the stator is reduced, so that the magnetic resistance on the back side of the stator slot, that is, the iron core outer diameter side is reduced, and the required field current for the same output is reduced. It is.

FIG. 4 shows characteristics regarding the relationship between the current density β and the total loss generated in the rotor winding and the stator winding. On the basis of this characteristic, looking at the range of 8A / mm ² ≤ β ≤ 11A / mm ² , the total loss generated in the rotor and stator windings is between 8A / mm ² and 9A / mm ² It can be seen that it is the smallest and gradually increases on both sides.

From this, it can be said that the generator loss can be reduced if the current density β is selected within the range of 8 A / mm ² ≦ β ≦ 11 A / mm ² . As shown in FIG. 3, the field current decreases with respect to the current density β and the loss generated in the rotor winding decreases, while the Joule loss generated mainly in the stator winding increases. It is to do.

As described above, in the half-turn coils 4a and 4b forming the stator coil housed in the stator slot 5 shown in FIG. 1, the number of the solid strands 4c constituting the half-turn coil is set to the hollow strand 4d. By reducing the proportionality coefficient α obtained by dividing by the number of α and α = 2, and selecting the current density β of the coil in the range of 8 A / mm ² ≦ β ≦ 11 A / mm ² , field current can be reduced and lost. Can be reduced.

  In the first embodiment, even when the dimensions of the upper and lower coils 4a and 4b or the configurations or dimensions of the strands 4c and 4d are different, the above-described effects can be obtained if α and β are appropriately selected.

(Example 2)
FIG. 5 is a sectional view showing the configuration of the second embodiment of the present invention. As shown in FIG. 5, the cross section of the stator slot when α = 3 is shown. In addition, the same code | symbol is attached | subjected to the component same as Example 1. FIG.

  In the second embodiment, the configuration of the stator slot is the same as that of the stator slot except that the proportionality coefficient α obtained by dividing the number of solid wires constituting the half-turn coil by the number of hollow wires is α = 3. This is the same as the first embodiment.

  Even with such a configuration, an effect equal to or greater than that of the first embodiment can be obtained. At this time, even when the dimensions of the upper and lower coils, or the configuration or dimensions of the strands of the upper and lower coils are different, the advantages described above in the first embodiment can be obtained.

  As a modification of the second embodiment, when only the upper coil is set to α = 4 and only the lower coil is set to α = 1, the above-described effects can be obtained. It is done.

FIG. 3 is a cross-sectional view showing a basic configuration of a stator slot in the first embodiment of the present invention. The cross-sectional view which shows the basic composition of the generator which concerns on this invention. The characteristic view which shows the relationship between the current density (beta) in the 1st Example of this invention, and the temperature rise value (DELTA) Tf of the field winding at the time of a rated load. The characteristic view which shows the relationship between the current density (beta) in the 1st Example of this invention, and the total loss which generate | occur | produces in a rotor winding and a stator winding. The cross-sectional view which shows the basic composition of the stator slot in the 2nd Example of this invention.

Explanation of symbols

  1: rotor, 2: stator core, 4a: upper coil, 4b: lower coil, 4c: solid wire, 4d: hollow wire, 5: stator slot.

Claims (6)

A stator of a generator arranged concentrically with respect to a rotor via an air gap, the stator having an iron core so that the iron core follows the axis of the rotation axis of the rotor. A plurality of coil slots extending to store the stator coil are provided, and the stator coil is formed of solid and hollow wire conductors that are cooled directly or indirectly by a refrigerant, and the stator core A half-turn coil composed of an upper coil and a lower coil connected to each other at ends protruding from both side surfaces, wherein the wire conductor is a portion housed in the coil slot and extends from the coil slot. In the stator of the generator formed so as to be continuously twisted and shifted toward the current direction,
The proportionality coefficient α obtained by dividing the number of solid wires constituting the half-turn coil by the number of hollow wires is 2 or more, and the current density β of the coil is 8 A / mm ² ≦ β ≦ 11 A / mm A generator stator characterized by being in the range of ² . In the stator of the generator according to claim 1,
The generator stator, wherein the proportionality coefficient α is 3 or more. In the stator of the generator according to claim 1,
The generator stator, wherein the upper coil and the lower coil have the same proportionality coefficient α. In the stator of the generator according to claim 1,
The generator stator, wherein the upper coil and the lower coil have different proportionality coefficients α. In the stator of the generator according to claim 4,
The generator stator, wherein the proportional coefficient α is α = 4 only for the upper coil. The generator according to claim 4,
The proportional coefficient α is α = 1 only for the lower coil.

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