JPS58146832A - Method for monitoring shaft torsional vibration and fatigue of turbine generator - Google Patents

Abstract

PURPOSE:To monitor exactly shaft torsional vibration and fatigue of a turbine generator, by adjusting a parameter of a mathematical model of a modal analyzing method by calculated modal damping, and deciding torsional vibration and stress of a shaft system. CONSTITUTION:By a damping operation part 8a of a signal processing part 8, torsional natural vibration of a shaft 4, modal damping, etc. are deciced from shaft torsional angle displacement from torsional angle detecting parts 5a, 5b. In accordance with decision of them, in a torsional vibration and stress calculating part 8b, a mathematical parameter by set modal analysis by electric torque and vapor pressure from detecting parts 6, 7 is adjusted, and a torsional vibration and stress state of each part of the shaft 4 is calculated. Subsequently, by a compare-operating part 8c, a calculation result of the calculating part 8b is compared with shaft torsional angle displacement, and in case when its error is large, the mathematical model parameter is readjusted, and it is repeated until the error becomes small. In this way, in accordance with a correct calculation result of the claculating part 8b, shaft torsional vibration and fatigue of a turbine generator is monitored exactly through a fatigue and life operating part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft torsional vibration/fatigue monitoring method for a turbine generator for monitoring the torsional vibration, stress, and degree of fatigue damage occurring in the shaft system of a rotating machine consisting of a steam turbine and a turbine generator.

[Technical weight of the invention]

Generally, steam turbine generators are high pressure. Medium pressure.

It consists of a low-pressure steam turbine, a power generator 811 (rotor), an exciter, and a turbine shaft that connects these. When the machine is operating in a steady state, the torsional vibration of the shaft and the resulting stress vibration of each part of the shaft are minute, but in the event of a sudden short llf1 failure. At low speeds and high-speed re-closing failures, when the force system and shaft torsion system resonate.

Furthermore, during asynchronous start-up, sudden transient torsional vibration and stress, or sinusoidal vibration and stress with sudden increase in rocking motion occur on the turbine shaft, and this unsteady torsion II &
The shaft may become fatigued and break due to movement.

For this reason, monitoring the shaft torsional vibration during operation, estimating the stress generated in each part of the shaft from the torsional angular deformation, and evaluating the degree of fatigue damage in that part is extremely important in terms of life design and operation of the rotating shaft. It's important. In particular, excessive torsional vibration occurring in the turbine generator shaft causes a large degree of fatigue on the shaft system, and it is very important to measure and evaluate this stress value within a short period of time during operation.

[Background technology points]

Therefore, although torsional vibration detection and stress measurement of such rotating shaft systems have been conventionally performed, vibration detection at multiple locations of the shaft system,
When performing stress adjustment, it is necessary to install a measuring device for each measurement point (part to be evaluated), which is extremely uneconomical, and there is no reliable method in terms of the life of the detector.
I cannot say that it is. Furthermore, due to various factors, it is not possible to monitor the torsional vibration, stress, and fatigue value of the shaft system in a thorough manner.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to provide an economical and reliable method that can accurately measure torsional vibration, stress state, and fatigue damage in each part of the shaft system, and reduce the degree of fatigue damage to 8 categories. An object of the present invention is to provide a method for monitoring shaft torsional vibration and fatigue of a high-performance turbine generator.

[Summary of the invention]

In the present invention, the torsional vibration and stress state of the turbine shaft system at t1m strongly depends on the torsional damping of the entire shaft system, and this damping is influenced by the load fluctuation of the steam turbine and the magnitude of vibration and stress applied to the turbine shaft. This study focuses on the fact that the larger the latter state is, the greater the damping of the entire system tends to be.

Therefore, in order to achieve the above object, the present invention simultaneously detects the shaft screw υ angular displacement, 4-kilo torque, and steam pressure at multiple locations in the shaft system of a rotating machine consisting of a steam turbine and a turbine generator msi, and detects the shaft torsion. From the angular displacement, find the natural frequency of the shaft system and its damping, and from this, set the parameters of the mathematical model using the modal analysis method using the electricity 1 lux and steam pressure as inputs to calculate the shaft torsional angular displacement. It is characterized by comparing the detected amount and setting an appropriate mathematical model to monitor the shaft torsional vibration, stress, and fatigue damage degree of each part of the shaft system.

[Embodiments of the invention]

An embodiment of the present invention shown in the drawings will be described below.

The figure is a block diagram showing an example of the shaft torsional vibration monitoring method of a turbine generator according to the present invention. In the figure, 1 is a steam turbine consisting of high pressure, intermediate pressure, and low pressure; is an exhaust leaf iterator, which are connected by a turbine shaft 4 to constitute a turbine generator shaft system.

On the other hand, ib is the torsion angle of the turbine @4, or the relative screw of the shaft! Shaft torsion angle detection g that detects fluctuating vibration and stress components related to the rotation angle; # is an electric torque detection unit that detects the electric torque applied to the turbine power generation fi2; This is the detection part. Moreover, 8 is each of the above-mentioned detection parts Sm, 6b, 6. This is a signal processing unit that receives the shaft torsion angular displacement detected by r, the 4K torque, and the steam pressure as inputs, and processes these input quantities into digital or analog signals. Its internal configuration is as follows. .

In other words, in the natural frequency/damping calculation section la,
From the shaft torsion displacement detected by the shaft torsion angle detection unit 1m, lb between two points, the torsion natural frequency Nfi (
1-1 to 11th order) and damping corresponding to each natural frequency that will change over time, that is, modal damping 81(t) (1-1 to a order). Next, in the torsional vibration/stress calculation section 8b, each of the detection sections 6.
Parameters of the Suki model based on the modal analysis method of the entire shaft system set in advance, which inputs the electric torque and steam pressure, which are the output quantities from 1.

The above Nf j (Jswlxa), 8 j(t)
(j m1~tr ) to calculate the torsional vibration and stress state of each part of the shaft. Next, the comparison calculation section 1c
Check the correctness of the calculation result by comparing it with the shaft torsional angular displacement between the two points above, and if the error is large, re-calibrate the parameters of the mathematical model within the variation range of 81(t) above. Adjust, calculate and compare the vibration number stress of each part of the shaft again, and repeat this process until the error becomes small.

As a result, if it is determined to be correct, the vibration of each part of the shaft
Fatigue life calculation unit tl calculates the degree of fatigue damage of each part from the stress state:
Then, output the result from Output-1#.

Note that in the above, t is the time of the input wave.

The former N-th value bubbles with time and remains unchanged, but the latter 81(t) generally has a characteristic that gradually decreases with time t. This is because 81 tends to become smaller as the vibration/stress state becomes smaller. Also, regarding 8i(t) - Law 1: It is not fixed,
This results in a pie-shaped change with some variation.

Furthermore, the basic mathematical model for analyzing the torsional vibration and stress of the shaft system described above is expressed as follows.

MΦ1〇Φ1 to Φ−F (6, 1') --------
--------(1) Here, Φ is a column vector representing the torsion angle of each part of the shaft, and Φ and Φ are the acceleration and velocity amounts, respectively. Also, mass and damping are applied to M and D, respectively.

It is a rigid matrix. Further, P(e*p) is an input column vector with electric torque e and steam pressure p as variables.

In this case, when a modal analysis method is applied to the above equation (1), the output of Φ is separated into outputs for each mode of the shaft system, and can be expressed as the sum of the outputs ρl of the first mode. That is, the output of ρ1 is obtained from the following equation as a result of the first mode.

mm ρ1 + old (1) - 10 to 1'-' (@ I
9) "" (2) Here, ntl, ki are the first
The mass and stiffness of the next mode are determined by equation (1).

81 (1 house damping # is the output quantity calculated, and the first-order natural frequency is equal to Nf 〒/mi. On the other hand, the first-order torsion angle output Φ of Φ is calculated by the modal analysis method as Desired.

Therefore, 8 m (1) and ml or ki in equation (2)
The parameters of are adjusted based on the Nth. However, if the parameter changes are large, the CIJ coupling matrix in equation (3) needs to be adjusted accordingly. Further, the comparison calculation unit 8c compares φ1 in equation (3) with the shaft torsional angular displacement.

In this way, the steam turbine 1 and the turbine power generation I12
．． In a steam turbine generator shaft system in which an equinator 1 is directly connected to a turbine shaft 4, a shaft torsion angle detection section tta
, ttb, the electric torque and steam pressure are simultaneously detected by the electric torque detection part I and the fume pressure detection part I, and first, the shaft torsion angle displacement between the two points is Natural frequency Nfj, which is the characteristic wax of the system, and modal damping8
4(t), and then set the parameters of a mathematical model based on the modal analysis method of the shaft system that is planned to use the electric torque and steam pressure as inputs as the above Nfi.

, S item t) to calculate the vibration and stress state of each part of the shaft, and then compare the results with the shaft torsional angular displacement between the above two points, and if the error is large, calculate the vibration and stress state of each part of the shaft. Adjust the parameters of the above mathematical model again, calculate and compare the vibration and stress states of each part of the shaft, and if the comparison results are judged to be correct (the error is small), the fatigue of each part can be determined from the vibration and stress state of each part of the shaft. It is designed to determine the degree of damage.

Therefore, according to the water ring torsional vibration monitoring method, the torsional vibration and stress of the shaft system are estimated by the modal analysis method using the shaft torsional angular displacement between two points of the shaft, and in order to improve the estimation accuracy, The special equipment of the shaft system is calculated from the shaft torsional displacement between the two points, and the results are used to subtract the parameters of the mathematical model using the modal analysis method, thereby reducing the error between the calculation result and the shaft torsional angular displacement between two points. Since the calculation is performed by re-adjusting the parameters up to the maximum, the estimation error is small and the estimation error is small, making it extremely accurate to estimate the l1WIb, stress state, and fatigue damage degree of the shaft system. It becomes possible to monitor the This not only prevents damage to the shaft system, but also allows the turbine generator to operate optimally in response to the operation of the power system. In addition, when detecting vibrations and measuring stress at multiple locations on the turbine generator shaft system, there is no need to install a measuring device for each measurement location as in the past, making such measurements simple, economical, and highly reliable. It is something that can be done.

In addition, although the above description was made using the torsional angular displacement between only two points of the shaft system, it is possible to implement the same method even if there are two or more points ζ of three or more points, and the more the number of points increases, the more beautiful each part becomes. The estimation accuracy of dynamic and stress states will be the same as above.

[Effect of invention]

As explained above, according to the present invention, the shaft torsional vibration of a turbine generator with high economic efficiency and reliability can be performed extremely accurately and easily, reducing the torsional vibration, stress state, and fatigue damage in each part of the shaft system.・Fatigue monitoring method can be provided.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1...Steam turbine, 2...Turbine generator, 1.
...Exciter-14...Turbine shaft, 1m, lb.
... Shaft torsion angle detection section, 6... Electric torque detection section, 7
...Steam pressure detection section, 8...Signal processing section, 8m...
- Natural frequency/damping calculation section, Jb...Torsional vibration/stress calculation section, 8C...Comparison calculation section, 9...Fatigue life calculation section, 10...Output section.

Claims (1)

[Claims] When monitoring shaft torsional vibration, stress, and fatigue of each part of a shaft in a rotating machine shaft system consisting of a steam turbine and a turbine generator, changes in shaft torsion angle, electric torque, and steam pressure at multiple locations of the shaft system are monitored. are simultaneously detected, and first, the natural frequency and modal damping of the shaft system are determined from the shaft torsion angular displacement. Next, the parameters of the mathematical model using the modal analysis method using the electric torque and steam pressure as input are calculated based on the natural frequency and modal damping to calculate the torsional vibration and stress state of each part of the shaft. Compare the result V with the shaft torsional angular displacement, and when the difference is large, -11 and vibration of the parameter until it becomes small. This method is characterized in that the stress state is repeatedly calculated and compared, and when the result is determined to be correct, the fatigue damage degree of each part is calculated from the vibration and stress state of each part of the shaft. Ring torsional vibration/fatigue monitoring method.