JPH01295640A - Rotor for rotary electric machine - Google Patents

Abstract

PURPOSE:To suppress torsional vibration of a rotor by equalizing the inherent vibration based on the torsional spring constant between an inertia disc fixed to the end of a rotor shaft and a rotor core to the inherent torsional vibration at rotor core section. CONSTITUTION:The rotor shaft of a rotor core 1 for large generator having axial length longer than the diameter is supported rotatably through bearings 4, 5. Then it is coupled through a coupling 2 arranged at the other end of the shaft to a turbine not shown. An inertia disc 3 is fixed to the other end of the shaft. Fixing position and the weight of the inertia disc 3 are set such that the inherent vibration based on the torsional spring constant of a vibration system comprising the shaft section 6 and the inertia disc 3 will be equal to the inherent torsional vibration at the section of the rotor core 1. By such arrangement, torsional vibration of the rotor is suppressed sufficiently even if the inherent torsional vibration at the rotor core section 1 matches to the magnetic exciting frequency, resulting in protection of turbine blade from damage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a vibration damping structure for a rotor of a rotating electrical machine, and particularly to a rotor structure for a rotating electrical machine that can suppress specific torsional vibrations.

(Prior art) The rotor of a turbine generator, etc. has a long iron core, and both ends of this iron core tend to vibrate and twist in opposite phases. is 5°, and in western Japan it is 60
7) and an electromagnetic excitation force with twice the frequency acts on the rotor, thereby causing torsional vibration in the rotor.

Now, if the distribution of electromagnetic force from the stator is uniform, and if the left and right moments of inertia are exactly the same when viewed from the center of the core, including the rotor core, then a vibration mode in which both ends of the core twist in opposite phases will be excited. However, in reality, the moments of inertia on the left and right sides will be non-uniform and will be subject to excitation by electromagnetic force. however.

Unless the vibration frequency (50Hz and 1007 in eastern Japan, 607 and 120H2 in western Japan) and the natural frequency of the torsional vibration of the iron core match or are very close to each other,
There were no problems. Note that when the two match (resonance), the torsional vibration is magnified and has a great influence on the equipment.

(Problem to be solved by the invention) In recent years, with the expansion of the capacity of turbine generators, the iron core of the rotor has also tended to become longer, and as a result, the natural frequency of the vibration mode in which both ends of the iron core are twisted in opposite phases has increased. It has become lower than before, and depending on the device, it may be quite close to the excitation frequency, or even coincide with it in some cases. In the unlikely event that resonance occurs.

The torsional vibration in the iron core expands and is transmitted to the turbine side, causing the turbine blades to vibrate greatly.

If there is a turbine blade whose natural frequency of bending vibration is close to the frequency of the torsional vibration with which it resonates, the vibration of the blade will be further amplified, resulting in fatal damage.

Considering the public nature of power plants, such a situation must be avoided at all costs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to be able to sufficiently suppress torsional vibration of one rotor even if the natural frequency of torsional vibration of the rotor core matches the electromagnetic excitation frequency. Our objective is to provide rotors for rotating electric machines.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the rotor of the present invention is provided with an inertia disk on a portion of the rotor outside the core component, and the torsion between the end of the rotor core and this inertia disk is The natural frequency of the torsional vibration system consisting of a spring constant is determined by the function of the rotor core.The function of the present invention will be explained with reference to FIGS. 2 to 4.

FIG. 2 shows a rotor of a turbine generator, which has an iron core 1 in the center, a coupling 2 to the turbine at the left end, and an inertia disk 3 at the right end.

In order to explain the vibration mode in which both ends of the iron core are twisted in opposite phases and the action of the present invention for damping this vibration, consider the mathematical model shown in FIG. In the figure, Ji and J2 are the equally concentrated moments of inertia at the left and right ends of the core, respectively, are the torsional spring constants of the core, Jd is the moment of inertia of the disc of inertia according to the present invention, and kd is the shaft from the end of the core to the disc of inertia. is the torsional spring constant of the part. Now, assuming that torque fluctuations due to a sinusoidal electromagnetic excitation force of frequency ω (ramp 2 seconds) act on the entire iron core group from the stator, the equation of motion of the model in FIG. 3 becomes as shown in equation (2).

However, θ□, θ2. θd is concentrated inertia, Jx+
The angular displacement of Jay Jd, (·) represents the second derivative of (·) with respect to time t, and T,,T, is the torque acting on J,,J,.

To simplify the explanation, if J, = J, = J, ω: = 2 are set as /J, Ja/J = α, then the resonance frequency ratio of the system Ω = ω/ω is determined from the left side of equation (2). Ω2=1+Master Niji α2+2α (2) However, it is assumed that Jd is determined according to the present invention so that kd/Jd=ω:.

If it is assumed that there is no Jd according to the present invention (Jd=O), then α=O and Ω2=1 from equation (2).

That is, the resonant frequency ω=ω. (ω.: J,, J, and k
), and the excitation frequency ω from the stator is the natural frequency ω of the system. As shown in FIG. 4(a), the amplitude of the angular displacement (θ, 02) of the system becomes maximum.

However, by attaching the inertia disk Jd according to the present invention, Ω becomes two resonant frequencies (i.e., 1 + quantity - 14/α2 + 2α
And 1+! +IA/α2+2α.

Conversely, when Ω=1, there is no maximum.

That is, according to the present invention, even when the torsional natural frequency of the system matches the excitation frequency from the stator, the
As shown in b), resonance can be avoided.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a turbine generator rotor according to an embodiment of the present invention, which has an iron core 1 in the center, a coupling 2 with a turbine at one end, and an inertia disk 3 at the other end. There is. It is assumed that the rotor is supported by bearings 4 and 5. In the figure, the part 6 indicated by [=] is the shaft part between the core end and the inertia disk, and this torsional spring constant kd and the inertia disk 3 are Between the moment of inertia Jd, Jla/Ja = ω. The values of J8 and kd are determined so that the following relationship holds true. However, ω. is the natural frequency of the torsional vibration of the rotor core, and is a mode in which both ends of the core twist in opposite phase.

5 to 8 show other embodiments of the present invention. In FIG. 5, the moment of inertia of the joint shaft 8 and the coupling flange 9 supported by the third bearing is Jd, and the spring constant of the shaft portion 10 is Jka/Ja with kd
” (It is configured to be 110.

Figure 6 shows the coupling flange 2 of the generator. The moment of inertia of the flange 11 on the turbine side and the turning gear 12 is Jde, and the torsion spring constant of the shaft portion 13 is kd, so that the above-mentioned relationship is established.

FIG. 7 shows the above-mentioned relationship between the moment of inertia Jd of the exciter 14 and the spring constant kd of the shaft portion 15, and FIG. 8 shows the relationship between the moment of inertia Jd of the ventilation fan flange 16 and the spring constant kd of the shaft portion 17. This is an example in which a similar relationship is established.

In addition, in FIG. 8, the same effect can be obtained even if the configuration is made using a ventilation fan flange on the turbine side.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the moment of inertia of the inertia disk and the attachment of this disk to the rotor of a rotating electrical machine are set so that the rotor has a natural frequency equal to the natural frequency of a specific torsional vibration of the rotor. By configuring the spring constant of the shaft between the position and the core end, resonance will not occur even if the frequency of torque fluctuation due to electromagnetic excitation force from the stator matches the natural frequency of the torsional vibration of the core. Effects such as being able to avoid causing vibration between the turbine blade and the turbine blade and causing fatal damage to the turbine blade can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a rotor of a rotating electric machine according to an embodiment of the present invention, and FIGS. 2 to 4 show the following according to the present invention: 1...rotor core, 2...coupling, 3... Inertia disk, 4...Bearing. 5... Bearing, 6... Shaft part, 7...
...Third bearing, 8...Joint shaft, 9.
...Coupling flange. 10... Shaft portion, 11... Turbine side coupling flange, 12...
・Turning gear, 13...Shaft part, 14...
・Exciter, 15...Shaft part, 16...
・Flange for ventilation fan. 17...Shaft Department Agent Patent Attorney Nori Ken Chika Yudo Ken Daishimaru Figure 1 Figure 2vA Figure 3'. [Figure 4 of relative numbers

Claims (1)

[Claims] An inertia disk is provided on a portion of the rotor other than the core, and the natural frequency of the torsional vibration system consisting of the torsional spring constant between the end of the rotor core and this inertia disk is the natural frequency of the torsional vibration of the rotor core. A rotor for a rotating electric machine, characterized in that the rotor is configured to match the number of rotors.