A method of identifying faults in a rotating machine rotor system and support system

Abstract

The present application relates to the technical field of rotating machinery vibration fault diagnosis, in particular to a method for identifying faults of rotating machinery rotor system and support system; arranging sensors; starting and stopping the machine set, testing the vibration change with the rotating speed during the starting and stopping of the machine set; constructing a relationship model between the shaft vibration and the bearing vibration at a certain rotating speed; constructing a relationship model between the shaft vibration and the bearing vibration at the full rotating speed; calculating two bearing vibration calculation values and two measured values according to the relationship model; comparing the difference between the bearing vibration calculation values and the two measured values to obtain error values; judging the fault part source according to the error values; specifying different frequency points and different rotating speeds, constructing the relationship model, repeating the judgment process, judging the source of the machine vibration fault at different frequency points and different rotating speeds, and achieving the effect of accurately judging whether the vibration source is the rotor system or the support system.

Description

Technical Field

[0001] This invention relates to the field of rotating machinery vibration fault diagnosis technology, and in particular to a method for identifying faults in the rotor system and support system of rotating machinery. Background Technology

[0002] Vibration is a significant factor affecting the safe and stable operation of various rotating machinery, such as steam turbines, generators, gas turbines, fans, pumps, and air compressors. Although these types of rotating machinery differ in their structural forms and working mechanisms, structurally they can all be considered as consisting of a rotor system and a support system, referred to simply as a rotor-support system.

[0003] Correspondingly, vibrations occurring on such equipment may be caused by the rotor system or the support system. To accurately analyze the causes of vibration faults and formulate remedial measures, there is an urgent need for a method that can accurately determine the source of vibration. Summary of the Invention

[0004] The purpose of this invention is to provide a method for identifying faults in the rotor system and support system of rotating machinery, so as to accurately determine whether the source of vibration is the rotor system or the support system.

[0005] To achieve the above objectives, the present invention provides a method for identifying faults in the rotor system and support system of rotating machinery, comprising the following steps: Deploy sensors; Start and stop the unit to test the vibration variation with speed during the start-up and shutdown process; Construct a model to model the relationship between shaft vibration and bearing vibration at a certain rotational speed; Construct a model relating shaft vibration and bearing vibration at full rotational speed; Two calculated values ​​and two measured values ​​of the vibration were obtained based on the relational model. The error value is obtained by comparing the calculated value of the vibration with the difference between the two measured values. Determine the location and source of the fault based on the error value; By specifying different frequency points and different speeds, a relationship model is constructed, and the judgment process is repeated to determine the source of machine vibration faults at different frequency points and different speeds.

[0006] In the step of deploying the sensors: A set of shaft vibration sensors is arranged at 45° and 135° directions directly facing the shaft in the bearing housing, and a set of bearing vibration sensors is arranged at the vertical and horizontal directions in the bearing housing. The output signals of the four sensors are connected to a vibration analyzer to test the vibration value.

[0007] Among them, in the steps of starting and stopping the unit and testing the vibration change with speed during the start-up and shutdown process: At each rotational speed, the vibration waveforms output from two shaft vibration measurement points and two bearing vibration measurement points were tested, and the vibration spectrum at that rotational speed was obtained by fast Fourier transform.

[0008] In the steps of constructing a model of the relationship between shaft vibration and bearing vibration at a certain rotational speed: Let f be a certain frequency, and let the relationship model between shaft vibration and bearing vibration at the i-th rotational speed be: ; In the formula, T ij (f) reflects the transmission relationship characteristics between the two shaft vibrations and the two bearing vibrations.

[0009] In the steps of constructing the relationship model between shaft vibration and bearing vibration at full rotational speed: For a specified analysis frequency point f, the relationship models between shaft vibration and bearing vibration at multiple rotational speeds are combined into a global analysis model: ; In the formula, the subscript n represents the rotational speed. For vertical and horizontal bearing vibrations, the above formula can be decomposed into two sets of equations: ; In short: ; The above equation can be solved when n≥2.

[0010] In the step of obtaining two calculated values ​​and two measured values ​​of vibration based on the relational model: Singular value decomposition (SVD) is used to eliminate the ill-conditioned nature of matrix A. SVD is performed on matrix A to obtain the left singular matrix U, the right singular matrix V, and the singular value matrix. : ; The singular value matrix is ​​a diagonal matrix and satisfies Calculate the contribution rate of singular values : ; when The singular value matrix is ​​modified to obtain the modified singular value matrix. for: ; when Singular value matrix for: ; Calculate the transmission relationship between shaft vibration and bearing vibration: ; Specify the frequency point f to be analyzed and the rotational speed to be analyzed, and record the measured values ​​of vertical and horizontal bearing vibration. Two shaft vibration test values ​​at this rotational speed Transmission relationship between shaft vibration and bearing vibration The calculated values ​​of the two vibrations were obtained. : .

[0011] In the step of comparing the calculated vibration value with the difference between two measured values ​​to obtain the error value: Comparing the two calculated values ​​of vibration and measured values The difference between the calculated and measured values ​​is taken as the error, with the maximum absolute value of the difference between the two values ​​being the largest. : .

[0012] In the step of determining the source of the fault based on the error value: when When the vibration is mm / s, the bearing vibration can be entirely transmitted by the shaft vibration, and the vibration comes from the rotor system; when At mm / s, bearing vibration can be partially transmitted by shaft vibration, and the vibration comes from both the rotor system and the support system. when When the vibration is at a speed of mm / s, the bearing vibration cannot be transmitted from the shaft vibration, the support characteristics change, and the vibration originates from the support system.

[0013] In the step of determining the source of the fault based on the error value: Using fuzzy mathematics, a fuzzy membership function y is defined: ; according to Calculate y based on the value of y, and then determine the following: When y < 0, the fault originates from the rotor system; When y≥0, the fault originates from the support system.

[0014] This invention discloses a method for identifying faults in the rotor and support systems of rotating machinery. The method involves deploying sensors; starting and stopping the unit to test the vibration variation with rotational speed during startup and shutdown; constructing a relationship model between shaft vibration and bearing vibration at a certain rotational speed; constructing a relationship model between shaft vibration and bearing vibration at all rotational speeds; calculating two calculated bearing vibration values ​​and two measured values ​​based on the relationship model; comparing the difference between the calculated bearing vibration value and the two measured values ​​to obtain an error value; determining the source of the fault based on the error value; specifying different frequency points and different rotational speeds, constructing relationship models, and repeating the judgment process to determine the source of machine vibration faults at different frequency points and different rotational speeds, thereby accurately determining whether the vibration originates from the rotor system or the support system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of the steps of the method for identifying faults in the rotor system and support system of rotating machinery according to the present invention.

[0017] Figure 2 This is a schematic diagram of the sensor installation structure of the present invention.

[0018] Figure 3 This is a schematic diagram of the vibration spectrum installation structure of the present invention at each rotational speed.

[0019] 1-Bearing housing, 2-Rotating shaft, 3-Y-axis vibration, 4-Vertical bearing vibration, 5-X-axis vibration, 6-Horizontal bearing vibration. Detailed Implementation

[0020] Please see Figures 1-3 The present invention provides a method for identifying faults in the rotor system and support system of rotating machinery, comprising the following steps: S1: Arrange the sensors; S2: Start and stop the unit to test the vibration change with speed during the start-up and shutdown process; S3: Construct a model of the relationship between shaft vibration and bearing vibration at a certain rotational speed; S4: Construct a model of the relationship between shaft vibration and bearing vibration at full rotational speed; S5: Based on the relational model, two calculated values ​​and two measured values ​​of the vibration were obtained; S6: Compare the calculated vibration value with the difference between the two measured values ​​to obtain the error value; S7: Determine the source of the fault location based on the error value; S8: Specify different frequency points and different speeds, build a relationship model, repeat the judgment process, and determine the source of machine vibration faults at different frequency points and different speeds.

[0021] In this embodiment, sensors are first deployed, and then the unit is started and stopped to test the vibration variation with rotational speed during startup and shutdown. A relationship model between shaft vibration and bearing vibration at a specific rotational speed is then constructed, followed by another relationship model across all rotational speeds. Based on these models, two calculated bearing vibration values ​​and two measured values ​​are obtained. The difference between the calculated and measured values ​​is compared to obtain the error value. The source of the fault is then determined based on the error value. Finally, different frequency points and rotational speeds are specified, and a relationship model is constructed. The above judgment process is repeated to determine the source of machine vibration faults at different frequency points and rotational speeds, achieving the effect of accurately determining whether the vibration originates from the rotor system or the support system.

[0022] Furthermore, in the step of deploying the sensors: A set of shaft vibration sensors is arranged at 45° and 135° on the bearing housing 1, facing the rotating shaft 2. A set of bearing vibration sensors is arranged in the vertical and horizontal directions of the bearing housing 1. The output signals of the four sensors are connected to a vibration analyzer to test the vibration value.

[0023] In this embodiment, such as Figure 2 As shown, large rotating machinery commonly installs two different types of vibration sensors on its bearings: shaft vibration and bearing vibration. Shaft vibration measuring points are installed on bearing housing 1, directly facing the rotating shaft 2, measuring the vibration of the rotating shaft 2 relative to bearing housing 1. Two shaft vibration measuring points are installed at angles of 45° and 135° to the horizontal direction, defined as X-axis shaft vibration 5 and Y-axis shaft vibration 3, respectively. Bearing vibration measuring points are installed in the vertical and horizontal directions of bearing housing 1, defined as vertical bearing vibration 4 and horizontal bearing vibration 6, respectively, measuring the vibration of bearing housing 1 relative to the ground. Shaft vibration and bearing vibration are used together for vibration monitoring and protection of rotating machinery. Currently, the location of the fault is mainly determined based on the ratio of the amplitudes of shaft vibration and bearing vibration. When shaft vibration is high and bearing vibration is low, the fault mainly comes from the rotor system. If the shaft vibration and bearing vibration are both large, then the fault mainly comes from the rotor system. If the shaft vibration is small and the bearing vibration is large, then the fault mainly comes from the support system, and the main reason is that the support system has insufficient stiffness. If the shaft vibration and bearing vibration are small, then the rotating machinery will have relatively small vibrations, be in normal condition, and have no faults.

[0024] Furthermore, in the steps of starting and stopping the unit and testing the vibration variation with speed during the start-up and shutdown processes: At each rotational speed, the vibration waveforms output from two shaft vibration measurement points and two bearing vibration measurement points were tested, and the vibration spectrum at that rotational speed was obtained by fast Fourier transform.

[0025] In this embodiment, the unit is started and stopped, and the vibration changes with rotational speed during the start-up and shutdown processes are tested. The vibration waveforms output from two shaft vibration measuring points and two bearing vibration measuring points are measured. The vibration spectrum at this rotational speed is obtained by fast Fourier transform, denoted as: A xi (f1), A xi (f2), A xi (f3)......; A yi (f1), A yi (f2), A yi (f3)......; B xi (f1), B xi (f2), B xi (f3)......; B yi (f1), B yi (f2), B yi (f3).......

[0026] In the formula, f1, f2... are the frequency points to be analyzed, the subscript i represents the i-th rotational speed point, and A... x A y B x B y These represent X-axis vibration 5, Y-axis vibration 3, horizontal bearing vibration, and vertical bearing vibration, respectively. Axial vibration is measured by vibration displacement in mm, using peak-to-peak value. Bearing vibration is measured by vibration velocity in mm / s, using root mean square value.

[0027] Furthermore, in the steps of constructing a model of the relationship between shaft vibration and bearing vibration at a certain rotational speed: Let f be a certain frequency, and let the relationship model between shaft vibration and bearing vibration at the i-th rotational speed be: ; In the formula, T ij (f) reflects the transmission relationship characteristics between the two shaft vibrations and the two bearing vibrations.

[0028] In this embodiment, the analysis is carried out using a certain frequency f as an example; other frequencies can be analyzed using the same method. The relationship model between shaft vibration and bearing vibration at the i-th rotational speed is denoted as: .

[0029] Furthermore, in the steps of constructing a model of the relationship between shaft vibration and bearing vibration at full rotational speed: For a specified analysis frequency point f, the relationship models between shaft vibration and bearing vibration at multiple rotational speeds are combined into a global analysis model: ; In the formula, the subscript n represents the rotational speed. For vertical and horizontal bearing vibrations, the above formula can be decomposed into two sets of equations: ; In short: ; The above equation can be solved when n≥2.

[0030] Furthermore, in the step of obtaining two calculated values ​​and two measured values ​​of vibration based on the relational model: Singular value decomposition (SVD) is used to eliminate the ill-conditioned nature of matrix A. SVD is performed on matrix A to obtain the left singular matrix U, the right singular matrix V, and the singular value matrix. : ; The singular value matrix is ​​a diagonal matrix and satisfies Calculate the contribution rate of singular values : ; when The singular value matrix is ​​modified to obtain the modified singular value matrix. for: ; when Singular value matrix for: ; Calculate the transmission relationship between shaft vibration and bearing vibration: ; Specify the frequency point f to be analyzed and the rotational speed to be analyzed, and record the measured values ​​of vertical and horizontal bearing vibration. Two shaft vibration test values ​​at this rotational speed Transmission relationship between shaft vibration and bearing vibration The calculated values ​​of the two vibrations were obtained. : .

[0031] Furthermore, in the step of comparing the calculated vibration value with the difference between the two measured values ​​to obtain the error value: Comparing the two calculated values ​​of vibration and measured values The difference between the calculated and measured values ​​is taken as the error, with the maximum absolute value of the difference between the two values ​​being the largest. : .

[0032] In this embodiment, the matrix A, composed of shaft vibration values ​​from two measuring points at different rotational speeds, exhibits strong ill-conditioning. Singular value decomposition (SVD) is used to eliminate the ill-conditioning of matrix A. SVD is performed on matrix A to obtain the left singular matrix U, the right singular matrix V, and the singular value matrix. Specify the frequency point f to be analyzed and the rotational speed to be analyzed, and record the measured values ​​of vertical and horizontal vibration. Two shaft vibration test values ​​at this rotational speed Transmission relationship between shaft vibration and bearing vibration The calculated values ​​of the two vibrations were obtained. By comparing the calculated vibration value with the two measured values, the error value is obtained. .

[0033] Furthermore, in the step of determining the source of the fault based on the error value: when When the vibration is mm / s, the bearing vibration can be entirely transmitted by the shaft vibration, and the vibration comes from the rotor system; when At mm / s, bearing vibration can be partially transmitted by shaft vibration, and the vibration comes from both the rotor system and the support system. when When the vibration is at a speed of mm / s, the bearing vibration cannot be transmitted from the shaft vibration, the support characteristics change, and the vibration originates from the support system.

[0034] In this embodiment, At speeds of mm / s, bearing vibration can be entirely transmitted by shaft vibration, with the vibration originating from the rotor system; At speeds of mm / s, bearing vibration can be partially transmitted from shaft vibration; the vibration originates simultaneously from both the rotor system and the support system. At speeds of mm / s, bearing vibration cannot be transmitted from shaft vibration, the support characteristics change, and the vibration originates from the support system.

[0035] Furthermore, in the step of determining the source of the fault based on the error value: Using fuzzy mathematics, a fuzzy membership function y is defined: ; according to Calculate y based on the value of y, and then determine the following: When y < 0, the fault originates from the rotor system; When y≥0, the fault originates from the support system.

[0036] In this embodiment, according to Calculate y based on the value of y, and determine the source of the fault based on the value of y: if y < 0, the fault originates from the rotor system; if y ≥ 0, the fault originates from the support system.

[0037] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for identifying faults in the rotor system and support system of rotating machinery, characterized in that, Includes the following steps: S1: Arrange the sensors; arrange a set of shaft vibration sensors facing the shaft at 45° and 135° on the bearing housing, and arrange a set of bearing vibration sensors in the vertical and horizontal directions on the bearing housing. Connect the output signals of the four sensors to the vibration analyzer to test the vibration value. S2: Start and stop the unit, and test the vibration at at least two different speeds during the start-up and shutdown process. At each speed, test the vibration waveform output by two shaft vibration measuring points and two bearing vibration measuring points, and obtain the vibration spectrum at that speed through fast Fourier transform. S3: Construct a relationship model between shaft vibration and bearing vibration at a certain rotational speed; Let f be a certain frequency, and denote the relationship model between shaft vibration A and bearing vibration B at the i-th rotational speed as follows: ； In the formula, T ij (f) reflects the transmission characteristics between the two shaft vibrations and the two bearing vibrations; B x,i (f) represents the vibration value at frequency f in the x-direction at the i-th rotational speed, B y,i (f) represents the vibration value at frequency f in the y-direction at the i-th rotational speed, A x,i (f) represents the shaft vibration value at frequency f in the x-direction at the i-th rotational speed, A y,i (f) represents the shaft vibration value at frequency f in the y direction at the i-th rotational speed; S4: Construct a relationship model between shaft vibration and bearing vibration at all speeds; for a specified analysis frequency point f, combine the relationship models between shaft vibration and bearing vibration at at least two speeds into a global analysis model, and use the measured values ​​of shaft vibration and bearing vibration at each speed to form a system of equations. When the speed n≥2, solve the system of equations using the singular value decomposition method to obtain the transmission relationship between shaft vibration and bearing vibration. ; S5: Specify the frequency point f to be analyzed and the rotational speed to be analyzed, based on the two measured shaft vibration values ​​and the transmission relationship at the analyzed rotational speed. The calculated values ​​of the two vibrations were obtained. ; S6: Compare the differences between the two calculated vibration values ​​and the two measured vibration values ​​corresponding to the speed to be analyzed, and take the maximum absolute value of the difference as the error value. According to the error value Determine the location and source of the fault; S7: Specify different frequency points and different speeds, repeat the judgment process of S3~S6 above, and determine the source of machine vibration faults at different frequency points and different speeds.

2. The method for identifying faults in the rotor system and support system of rotating machinery as described in claim 1, characterized in that, In step S4: The overall analysis model is as follows: ； In the formula, the subscript n represents the number of rotational speeds. For vertical and horizontal bearing vibrations, the above formula can be decomposed into two sets of equations: ； In short: 。 3. The method for identifying faults in the rotor system and support system of rotating machinery as described in claim 2, characterized in that, In step S5: Singular value decomposition (SVD) is used to eliminate the ill-conditioned nature of matrix A. SVD is performed on matrix A to obtain the left singular matrix U, the right singular matrix V, and the singular value matrix. : ； The singular value matrix is ​​a diagonal matrix and satisfies Calculate the contribution rate of singular values : ； when The singular value matrix is ​​modified to obtain the modified singular value matrix. for: ； when Singular value matrix for: ； Calculate the transmission relationship between shaft vibration and bearing vibration: ； Specify the frequency point f to be analyzed and the rotational speed to be analyzed, and record the measured values ​​of vertical and horizontal bearing vibration. The measured values ​​of the two shaft vibrations at this speed Transmission relationship between shaft vibration and bearing vibration The calculated values ​​of the two vibrations were obtained. : 。 4. The method for identifying faults in the rotor system and support system of rotating machinery as described in claim 1, characterized in that, In the step of determining the source of the fault based on the error value: when At a speed of mm / s, all bearing vibration is transmitted by shaft vibration, and the vibration originates from the rotor system; when At mm / s, the vibration of the bearing is transmitted by the shaft vibration, and the vibration comes from both the rotor system and the support system. when When the vibration is at a speed of mm / s, the bearing vibration cannot be transmitted from the shaft vibration, the support characteristics change, and the vibration originates from the support system.

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