JP2005098258A - Turbine generator shaft torsional vibration detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torsional vibration detection method for a turbine generator that can individually calculate a torsion torque appearing in each part of a rotating shaft system including a turbine only by detecting a rotational speed deviation on the rotating shaft of the generator. .
In A generator 1 and a turbine 2-5 turbogenerator coupled with the rotating shaft 6, only provided a rotational angle sensor comprising a gear 7 and the electromagnetic pickup 8 to the rotary shaft ₆₁ of the generator 1, the sensor Is input to the rotational speed deviation calculating unit 9 to calculate the rotational speed deviation Δω, which is supplied to the arithmetic processing unit 10, where the above-described rotating shaft system of the turbine generator was simulated. The rotational speed deviation Δω is processed according to an arithmetic model based on the simultaneous equations of motion, and the torsional torque T (T ₁₂ , T ₂₃ , T ₃₄ , T ₄₅ ) of each part of the rotating shaft 6 is calculated.
[Selection] Figure 1

Description

  The present invention relates to a turbine generator generator shaft and a method for detecting torsional vibration appearing on the turbine shaft, and in particular, a turbine generator suitable for calculating shaft life from the magnitude and number of times of torque when torsional vibration occurs. The present invention relates to a shaft torsional vibration detection method.

  In general, a turbine generator constitutes a so-called rotating shaft system in which a shaft of a turbine is directly connected to a shaft of a generator and each shaft is connected as a whole.

  Therefore, in such a turbine generator, if a large torque fluctuation appears in the generator when a sudden short circuit occurs or during reclosing operation, torsional (torsional) vibration using the generator as an excitation source (vibration generation source) Will be caused to the rotating shaft system.

  When this torsional vibration is caused, the generator shaft and the turbine shaft are repeatedly subjected to stress, and fatigue may appear in a weak portion of the rotating shaft system, which may shorten the shaft life. .

  Therefore, there is a method for detecting the torsional vibration appearing in the rotating shaft system of the turbine generator and calculating the fatigue life of the rotating shaft system from the magnitude and number of torsion torques generated in the rotating shaft system and the SN curve of the shaft portion. Conventionally, it has been proposed (see, for example, Patent Document 1).

Here, in this conventionally proposed method, in order to measure torsional vibration, a rotation angle detector comprising a gear and a pickup is provided at an arbitrary position of the rotating shaft system, and the rotation speed deviation related to the relative torsion angle is provided. , And the output of the generator is measured by a wattmeter, and the direct current component of torque and the low frequency torsion torque are measured from these measurement results.
JP-A-53-73301

  The above prior art does not consider torsional vibration using a generator as an excitation source, and has a problem in detecting torsional torque in each part of the rotating shaft system.

  In the conventional technology, the rotational speed deviation is detected at an arbitrary position in the shaft system of the turbine generator, but when the generator becomes an excitation source during sudden short circuit or reclosing operation, In the detection, accurate torsional vibration information cannot be detected due to the influence of natural damping or the like, and a problem arises in accurate detection of the torsional torque of each part of the shaft system.

  Further, in the prior art, it is necessary to separately obtain and store the torsion torque characteristics with respect to the detected rotational speed deviation.

  Furthermore, in the prior art, it is necessary to measure the output of the generator. In this case, the DC component of the torque fluctuates depending on the rotational speed and the magnitude of the load. There wasn't.

  An object of the present invention is to provide a method for detecting a torsional vibration of a turbine generator that can individually calculate a torsion torque appearing in each part of a rotating shaft system including a turbine only by detecting a rotational speed deviation on the rotating shaft of the generator. It is to provide.

  In the turbine generator in which the rotating shaft of the generator and the rotating shaft of the turbine are coupled to each other, the number of revolutions appearing on the rotating shaft on the opposite side of the generator coupled to the rotating shaft of the turbine. By calculating the torsional torque appearing at each part of the rotating shaft by measuring the deviation and processing the measured rotational speed deviation according to a calculation model based on simultaneous equations of motion simulating the rotating shaft system of the turbine generator Achieved.

  Here, the fatigue life in each part of the rotating shaft may be estimated from the calculation result of the torsion torque appearing in each part of the rotating shaft.

  At this time, the fatigue life in each part of the rotating shaft may be estimated with reference to the maximum value of the torsion torque appearing in each part of the rotating shaft and the SN curve, and appears in each part of the rotating shaft. Based on the torsional torque, it may be estimated using the stress frequency coefficient method or the minor cumulative damage law.

  According to the present invention, at the end of the turbine generator on the generator side, only by measuring the rotational speed deviation that appears on the rotating shaft, it appears in each part of the rotating shaft system when a sudden short circuit occurs or during reclosing operation. The shaft torsion torque can be accurately calculated.

  As a result, according to the present invention, the shaft life can be calculated more accurately, and high reliability based on accurate maintenance can be reliably obtained.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A turbine generator shaft torsional vibration detection method according to the present invention will be described in detail below with reference to the illustrated embodiments. First, FIG. 1 schematically shows an example of a turbine power generation facility to which an embodiment of the present invention is applied. FIG.

  Here, the turbine power generation facility shown in FIG. 1 is a dual turbine generator in which one generator 1 is driven by four turbines 2, 3, 4, and 5. 1 and the rotating shafts of the turbines 2, 3, 4, and 5 are coupled to each other to form a rotating shaft 6 that is connected as a whole.

Therefore, the rotating shaft 6 corresponds to the rotating shaft system described above. Therefore, hereinafter, the generator 1 and a portion located between the turbine 2 and the rotation shaft 6 _12, likewise rotating shaft 6 ₂₃ between the turbine 2 and 3, between the turbine 3 and 4 the rotation axis 6 ₃₄ of the rotary shaft 6 , between the turbine 4 and 5 and the rotary shaft 6 _45.

The rotation shaft on the opposite side of the person that is coupled to the time axis of rotation of the turbine 2 of the generator 1, a rotary shaft 6 ₁₇ As shown here, made of magnetic material such as steel A gear 7 is attached.

  Then, an electromagnetic pickup 8 is provided around the gear 7, whereby a rotation angle sensor is formed by a combination of the gear 7 and the electromagnetic pickup 8.

  Then, the output signal of the electromagnetic pickup 8 is input to the rotational speed deviation calculating unit 9 to calculate the rotational speed deviation, and this rotational speed deviation is supplied to the arithmetic processing unit 10 to calculate torsional vibration as will be described later. It has become so.

  Next, the operation of this embodiment will be described. First, when the generator 1 rotates, a pulse signal P is output from the electromagnetic pickup 8 due to a change in magnetic resistance caused by the teeth of the gear 7.

  At this time, each pulse of the pulse signal P is generated every time one tooth engraved around the gear 7 passes near the electromagnetic pickup 8. Therefore, the number of pulse signals P represents the rotation angle of the generator 1.

  For example, when a gear having 360 teeth is used as the gear 7, one pulse is generated every time the rotation angle of the generator 1 changes. The rotational speed (rotational speed) can be detected from the pulse period of the pulse signal P.

  Therefore, first, the rotational speed deviation calculation unit 9 calculates the rotational speed N from the period of the pulse signal P input from the electromagnetic pickup 8, calculates the rotational speed deviation Δω from this, and inputs it to the arithmetic processing unit 10.

  At this time, since the generator 1 is normally used as a synchronous generator, it is operated at a constant rotational speed (for example, 3000 rpm when the generator 1 is two poles at 50 Hz). The rotational speed deviation Δω can be calculated by comparing the calculated rotational speed N with a constant rotational speed.

  Next, the arithmetic processing unit 10 inputs the rotational speed deviation Δω from the rotational speed deviation calculating unit 9 and performs an operation according to the arithmetic model shown in FIG. 2 to obtain the torsion torque T and the torsion angle θ in each part of the rotating shaft system. calculate.

Here, the calculation model of FIG. 2 is constructed based on the simultaneous equation of motion described in the following (Equation 1), and the simultaneous equation of motion shown in (Equation 1) is: This is derived by simulating the rotating shaft system of the turbine generator shown in FIG.

  At this time, the meanings of symbols in the arithmetic model of FIG. 2 and the simultaneous equations of motion of (Formula 1) are as follows.

θ ₁₇ : Twisting angle appearing on rotating shaft 6 ₁₇ θ ₁₂ : Twisting angle appearing on rotating shaft 6 ₁₂ θ ₂₃ : Twisting angle appearing on rotating shaft 6 ₂₃ θ ₃₄ : Twisting angle appearing on rotating shaft 6 ₃₄ θ ₄₅ : Twisting angle appearing on rotating shaft 6 _{34 45} Torsion angle appearing at ₄₅ T ₁₂ : Torsion torque appearing at the rotating shaft 6 ₁₂ T ₂₃ : Torsion torque appearing at the rotating shaft 6 ₂₃ T ₃₄ : Torsion torque appearing at the rotating shaft 6 ₃₄ T ₄₅ : Torsion torque appearing at the rotating shaft 6 ₄₅ K _12: rotating shaft 6 ₁₂ of the spring constant K _23: spring constant K ₃₄ of the rotary shaft 6 _23: spring constant K ₄₅ of the rotary shaft 6 _34: rotational shaft of 6 ₄₅ spring constant M _2: turbine 2 moment of inertia (a constant)
M ₃ : moment of inertia of turbine 3 (constant)
M ₄ : moment of inertia of turbine 4 (constant)
M ₅ : moment of inertia of turbine 5 (constant)
Here, K _{12 to} K ₄₅ are literally constants, and M _{2 to} M ₅ are also constants as described above, and all are values inherent to the generator and turbine of the turbine power generation equipment. Two calculation models can be set.

Therefore arithmetic processing unit 10, using the arithmetic model of Figure 2 these constants are set, the arithmetic processing to the rotational speed difference Δω input from the rotational speed deviation calculating section 9 performs first torsion appears on the rotation shaft 6 ₁₂ torque T ₁₂ and appearing on the rotary shaft 6 ₂₃ torsional torque T _23, the torsional torque T ₃₄ appears on the rotation shaft 6 ₃₄ calculates the respective torsional torque T ₄₅ appearing on the rotating shaft 6 ₄₅ thereto.

In the case of this embodiment, the rotary shaft system for measuring the torsional vibration, only gear 7 and the electromagnetic pickup 8 provided on the rotating shaft 6 ₁₇ of the generator 1 as the vibration source of the torsional vibration, thereby rpm Deviation is measured.

Therefore, according to the above embodiment, the gear 7 to the rotary shaft 6 ₁₇ of the generator 1 is provided, the torsional torque appears in each section of the rotating shaft system including the turbine only by detecting the rotational speed deviation be calculated separately it can.

Further, according to this embodiment, since the rotation speed deviation is measured with the rotation axis 6 ₁₇ of the generator 1, it is possible to torsional vibrations prevented from being attenuated by the influence of the axial damping, therefore, the pressurized Excitation information input to the rotating shaft system of the turbines 2 to 5 from the generator 1 that is the vibration source can be accurately detected.

  As a result, there is no risk of being affected by the rotational speed or the magnitude of the load when calculating the torsion torque. Therefore, according to this embodiment, the torsional vibration is accurately grasped, and the torsion torque is accurately determined. It can be calculated.

Therefore, the arithmetic processing unit 10 refers to the maximum value of the torsional torques T _{23 to} T ₄₅ of each part of the rotating shaft system and the SN curve (Stress-Numbdr of cycles curve) calculated by the arithmetic model of FIG. This time, the lifetime in each part of the rotating shaft system formed by the rotating shaft 6 is estimated.

At this time, the torsional torque T _{23 to} T ₄₅ of each part of the rotating shaft system may be estimated by using a stress frequency coefficient method such as a well-known rain flow method or range pair method, and a minor cumulative damage law. The lifetime may be estimated using.

  Therefore, according to this embodiment, a highly accurate life estimation based on the accurate detected value of the torsion torque will be obtained.As a result, in consideration of the highly accurate life in each part of the rotating shaft system thus estimated, By reflecting this in the maintenance, it is possible to ensure the safe operation of the turbine power generation facility, and it is possible to easily ensure high reliability.

Incidentally, in the above embodiment, mounted on a rotary shaft ₆₁ of the generator 1, as a rotation angle sensor used to detect the rotational speed deviation, using a rotational angle sensor comprising a combination of the gear 7 and the electromagnetic pickup 8 However, the embodiment of the present invention is not limited to this, and may be, for example, an optical rotation angle sensor.

It is a block block diagram which shows an example of the turbine power generation equipment with which one Embodiment of the shaft torsion vibration detection method of the turbine generator by this invention was applied. It is a block diagram of the calculation model showing the equation of motion for shaft torsion torque calculation in one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Generator 2-5 Turbine rotor 6 Rotating shaft 7 Gear 8 Pickup 9 Rotational speed deviation calculation part 10 Arithmetic processing part

Claims (4)

In the turbine generator in which the rotating shaft of the generator and the rotating shaft of the turbine are mutually coupled,
Measuring the rotational speed deviation appearing on the rotating shaft on the opposite side of the generator connected to the rotating shaft of the turbine;
By processing the measured rotational speed deviation according to an arithmetic model based on simultaneous equations of motion simulating the rotating shaft system of the turbine generator,
A method for detecting a shaft torsional vibration of a turbine generator, comprising calculating a torsional torque appearing at each part of the rotating shaft. The shaft torsional vibration detection method according to claim 1,
A method for detecting a shaft torsional vibration of a turbine generator, wherein a fatigue life in each part of the rotating shaft is estimated from a calculation result of a torsion torque appearing in each part of the rotating shaft. The shaft torsional vibration detection method according to claim 2,
A method of detecting a shaft torsional vibration of a turbine generator, wherein the fatigue life in each part of the rotating shaft is estimated with reference to a maximum value of a torsion torque appearing in each part of the rotating shaft and an SN curve. The shaft torsional vibration detection method according to claim 2,
Fatigue life in each part of the rotating shaft is estimated based on torsional torque appearing in each part of the rotating shaft by using a stress frequency coefficient method or a minor cumulative damage law. Vibration detection method.

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