An analysis method for visualizing abnormal torsional vibration of a steam turbine

Abstract

The present invention discloses an analysis method for visualizing abnormal torsional vibration of a steam turbine, belonging to the technical field of steam turbine torsional vibration state monitoring. It solves the problem that it is difficult to monitor the torsional vibration state of a steam turbine generator set in real time in the prior art. The present invention includes the following steps: S1. Adopt non-contact measurement, draw a reference signal, and calculate the shafting torsional vibration signal; specifically: S11. Install an eddy current sensor and take measures to limit the bending vibration interference; S12. Draw a reference signal according to the principle of torsional vibration information extraction; S13. Calculate the real-time speed of the shafting; S14. Draw the shafting torsional angle signal; S2. Collect the unit state parameters; S3. Design a torsional vibration fault monitoring system according to the shafting torsional vibration signal and the unit state parameters. The present invention realizes the real-time monitoring of the torsional vibration of the steam turbine and the early warning analysis of dangerous parts, avoids the impact or fatigue cumulative damage of the shafting, and can be applied to the monitoring of the torsional vibration state of the steam turbine.

Description

Technical Field

[0001] The invention relates to abnormal torsional vibration monitoring of a steam turbine, and in particular to a visual analysis method for abnormal torsional vibration of a steam turbine, belonging to the technical field of torsional vibration state monitoring of a steam turbine. Background Art

[0002] Steam turbine generators play a leading role in power supply in power systems. Whether they can operate safely is directly related to the stability of the power system and the quality of electric energy. The insulation materials of steam turbine generators are exposed to harsh environments of high temperature and humidity for a long time, and are subjected to huge mechanical stress, making insulation failures very likely to occur. In addition to electrical insulation failures, there are also various mechanical failures. At the same time, the steam turbine generator itself has a complex mechanical structure and huge auxiliary equipment, so any failure in the steam turbine generator component may cause the entire system to stop operating.

[0003] The multiple rotors of the turbine generator shaft system, such as the high, medium and low pressure rotors of the turbine, the generator rotor, the exciter rotor, etc., are all important components of the turbine generator. The torsional vibration of the turbine generator shaft system refers to the torsional vibration of the shaft system caused by electromechanical disturbance or abnormal operation. In severe cases, it can cause excessive alternating torsional stress in certain sections or couplings of the shaft system, resulting in impact or fatigue cumulative damage to the shaft system, directly threatening the safe operation of the unit.

[0004] At present, some power plants do not pay enough attention to the torsional vibration status monitoring of steam turbine generator sets. Although some power plants are equipped with torsional vibration protection devices, the functions of the devices are relatively simple and cannot provide detailed data for the safe calculation of torsional vibration. Therefore, there is a problem in the prior art that the torsional vibration status of steam turbine generator sets is difficult to monitor in real time. A steam turbine torsional vibration monitoring data analysis method is needed, which uses fault data and analysis and calculation results to provide online and post-event torsional vibration status analysis, historical trend analysis, and fault diagnosis functions. Summary of the invention

[0005] A brief overview of the present invention is provided below in order to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0006] In view of this, in order to solve the problem in the prior art that the torsional vibration state of a steam turbine generator set is difficult to monitor in real time, the present invention provides a method for visualizing anomaly analysis of torsional vibration of a steam turbine.

[0007] The technical solution is as follows: A method for visualizing abnormal torsional vibration of a steam turbine comprises the following steps:

[0008] S1. Adopt non-contact measurement, draw the reference signal, and calculate the torsional vibration signal of the shafting;

[0009] Specifically:

[0010] S11. Install eddy current sensors and take measures to limit the bending vibration interference;

[0011] S12. Draw the reference signal according to the torsional vibration information extraction principle;

[0012] S13. Calculate the real-time rotational speed of the shafting;

[0013] S14. Draw the torsional angle signal of the shafting;

[0014] S2. Collect the unit status parameters;

[0015] S3. Design a torsional vibration fault monitoring system based on the torsional vibration signal of the shafting and the unit status parameters.

[0016] Furthermore, in S11, the first eddy current sensor and the second eddy current sensor are used. Taking the vertical center axis of the test gear as a reference, the method of symmetric installation at 180 degrees is adopted to limit the bending vibration interference and monitor the real-time rotational speed of the test gear.

[0017] Furthermore, in S12, according to the torsional vibration information extraction principle: when there is no torsional vibration in the shafting, the pulse signal output by the sensor is an equal-period pulse; let the reference signal be a non-torsional vibration pulse signal, the pulse number of the reference signal is i, i = 1, 2, 3... n, n is the number of teeth of the test gear, and the time width of the i-th pulse period of the reference signal is t i 。

[0018] Furthermore, in S13, according to the angle between two adjacent teeth of the test gear i and the rotational angular velocity ω of the shafting

[0019] The angle between two adjacent teeth of the test gear

[0020]

[0021] The rotational angular velocity ω of the shafting i is expressed as:

[0022]

[0023] The real-time rotational speed f of the shafting is expressed as:

[0024]

[0025] Further, in S14, when torsional vibration occurs to the rotating shaft, let the torsional angular displacement at the position of the i-th tooth of the test gear be Torsional angular displacement such that the time when the i-th tooth passes through the first eddy current sensor and the second eddy current sensor is advanced or delayed by a time Δt i ;

[0026] Torsional angular displacement such that the time when the i-th tooth passes through the first eddy current sensor and the second eddy current sensor is advanced or delayed by a time Δt i is expressed as:

[0027]

[0028] Bending vibration velocity component V y such that the time when the i-th tooth passes through the first eddy current sensor and the second eddy current sensor is advanced or delayed by a time Δt′;

[0029] Bending vibration velocity component V y such that the time when the i-th tooth passes through the first eddy current sensor and the second eddy current sensor is advanced or delayed by a time Δt′ is expressed as:

[0030]

[0031] where ω is the angular velocity and R is the radius of the test gear;

[0032] Let the time interval for the i-th tooth to pass through the first eddy current sensor be T i 1 and the time interval for the i-th tooth to pass through the second eddy current sensor be T i 2 ;

[0033] The time interval T for the i-th tooth to pass through the first eddy current sensor i 1 and the time interval T for the i-th tooth to pass through the second eddy current sensor i 2 are expressed as:

[0034]

[0035] The torsional angular displacement is expressed as:

[0036]

[0037] By integrating the reference values of each tooth of the test gear and the measured values of the instantaneous moments of each tooth, a torsional angular displacement sequence is obtained

[0038]

[0039] Combined with the time width sequence t i and the torsional vibration angular displacement sequence Plot the torsional angle signal of the shafting system.

[0040] Furthermore, in S3, the torsional vibration fault monitoring system includes a main monitoring view real-time interface, a rotational speed and torsional angle real-time interface, a steam turbine life assessment interface, and a historical data interface; the data displayed on the main monitoring view real-time interface includes the maximum value of the rotational speed per minute, the maximum value of the torsional angle per minute, the maximum value of the power per minute, the real-time current of the three-phase motor, the real-time voltage of the three-phase motor, and the external view of the steam turbine, and the changes of the above data parameters are displayed in real time, and an alarm prompt is given when the torsional angle parameter is too large; the data displayed on the rotational speed and torsional angle real-time interface includes the real-time data of the rotational speed, the real-time data of the torsional angle, the real-time data of the power, the maximum value of the rotational speed per minute, the maximum value of the torsional angle per minute, the maximum value of the power per minute, and the cumulative occurrence frequencies of the power, rotational speed, and torsional angle; the steam turbine life assessment interface highlights the determined dangerous parts, conducts life assessment on them, and displays the remaining life of the dangerous parts; the historical data interface records the torsional vibration fault data and provides safety analysis.

[0041] The beneficial effects of the present invention are as follows: The present invention uses a non-contact measurement arrangement sensor to obtain torsional vibration monitoring information, utilizes the pulse signal of the steam turbine test gear, and extracts the torsional vibration information of the shafting system; in the torsional vibration fault monitoring system, the main monitoring view real-time interface displays the rotational speed, torsional angle, power, real-time current of the three-phase motor, real-time voltage of the three-phase motor, and the external view of the steam turbine in real time, and highlights and evaluates the dangerous parts on the steam turbine life assessment interface, predicts their remaining life, the historical data interface records the torsional vibration fault data and conducts safety analysis; the present invention realizes the real-time monitoring of torsional vibration and the early warning analysis of dangerous parts, avoids the impact or fatigue cumulative damage of the shafting system, can analyze the fault cause according to the real-time monitoring data when a torsional vibration fault occurs, clarifies the responsibility boundary between the power plant and the power grid, and provides auxiliary diagnostic information for other faults of the unit, such as vibration faults. Description of the Drawings

[0042] The drawings described herein are used to provide a further understanding of the present invention, form a part of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0043] Figure 1 It is a schematic flow chart of an analysis method for visualizing abnormal torsional vibration of a steam turbine;

[0044] Figure 2 It is a schematic diagram of the installation position of the eddy current sensor;

[0045] Figure 3Schematic diagram of torsional vibration information extraction principle; among them, (a) is a schematic diagram of the relationship between the pulse width modulation signal and the torsional angle, (b) is a schematic diagram of the non-torsional vibration pulse signal, and (c) is a schematic diagram of the torsional vibration pulse signal and the torsional angle signal;

[0046] Figure 4 Schematic diagram of sensor signal and reference signal;

[0047] Figure 5 Principle of data acquisition and processing process of torsional vibration fault monitoring system;

[0048] Figure 6 Main monitoring view real-time interface;

[0049] Figure 7 Real-time interface of rotational speed and torsional angle;

[0050] Figure 8 Life assessment interface.

[0051] Reference numerals in the attached drawings: 1. First eddy current sensor; 2. Second eddy current sensor; 3. Test gear; 4. Bracket. Specific implementation mode

[0052] In order to make the technical solutions and advantages in the embodiments of the present invention clearer and more understandable, the following further details the exemplary embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0053] Refer to Figures 1-8 This embodiment is described in detail. An analysis method for visualizing abnormal torsional vibration of a steam turbine specifically includes the following steps:

[0054] S1. Adopt non-contact measurement, draw a reference signal, and calculate the shafting torsional vibration signal;

[0055] Specifically:

[0056] S11. Install an eddy current sensor and take measures to limit the bending vibration interference;

[0057] S12. Draw a reference signal according to the torsional vibration information extraction principle;

[0058] S13. Calculate the real-time rotational speed of the shafting;

[0059] S14. Draw the shafting torsional angle signal;

[0060] S2. Collect the unit status parameters;

[0061] S3. Design a torsional vibration fault monitoring system according to the shafting torsional vibration signal and the unit status parameters.

[0062] Further, in S11, the first eddy current sensor 1 and the second eddy current sensor 2 are used. Taking the vertical central axis of the test gear 3 as a reference, the method of symmetric installation at 180 degrees is adopted to limit the bending vibration interference, and the real-time rotational speed of the test gear 3 is monitored.

[0063] Specifically, the lateral vibration of the shaft will have a direct impact on the torsional vibration signal of the shafting, and this impact cannot be ignored. To achieve a higher measurement accuracy, measures should be taken to maximize the limitation of the bending vibration interference. The bending vibration interference can be suppressed by using two eddy current sensors to symmetrically install at 180 degrees to monitor the instantaneous rotational speed at each tooth of the test gear 3. The vertical component of the bending vibration will cause the measurement results of the two sensors to change with the same magnitude and opposite directions. Subsequently, the data measured by the two sensors are averaged to eliminate the influence of the bending vibration on the torsional vibration monitoring.

[0064] Further, in S12, according to the torsional vibration information extraction principle: when the shafting does not undergo torsional vibration, the pulse signal output by the sensor is an equal-period pulse; let the reference signal be a non-torsional vibration pulse signal, the pulse number of the reference signal is i, i = 1, 2, 3... n, n is the number of teeth of the test gear 3, and the time width of the i-th pulse period of the reference signal is t i ;

[0065] Specifically, when the shafting is at a constant rotational speed, that is, the shafting does not undergo torsional vibration, the pulse signal output by the sensor is an equal-period pulse. If the shafting undergoes torsional vibration, the pulse signal will show different pulse widths, that is, the pulse width modulation phenomenon; during the rotation of the shafting, the pulse signal contains not only the rotation frequency component but also the frequency component of the torsional vibration. Therefore, the non-contact measurement can be used to extract the torsional vibration information of the shafting.

[0066] Further, in S13, according to the angle between two adjacent teeth of the test gear 3 and the angular velocity ω of the shafting rotation i , the real-time rotational speed f of the shafting is calculated;

[0067] The angle between two adjacent teeth of the test gear 3 is expressed as:

[0068]

[0069] The angular velocity ω of the shafting rotation i is expressed as:

[0070]

[0071] The real-time rotational speed f of the shafting is expressed as:

[0072]

[0073] Furthermore, in S14, when torsional vibration occurs in the rotating shaft, let the torsional angular displacement at the position of the i-th tooth of the test gear 3 be Torsional angular displacement such that the time when the i-th tooth passes through the first eddy current sensor 1 and the second eddy current sensor 2 is advanced or delayed by a time Δt i ;

[0074] Torsional angular displacement such that the time when the i-th tooth passes through the first eddy current sensor 1 and the second eddy current sensor 2 is advanced or delayed by a time Δt i It is expressed as:

[0075]

[0076] Bending vibration velocity component V y such that the time when the i-th tooth passes through the first eddy current sensor 1 and the second eddy current sensor 2 is advanced or delayed by a time Δt';

[0077] Bending vibration velocity component V y such that the time when the i-th tooth passes through the first eddy current sensor 1 and the second eddy current sensor 2 is advanced or delayed by a time Δt' is expressed as:

[0078]

[0079] where ω is the angular velocity and R is the radius of the test gear 3;

[0080] Let the time interval for the i-th tooth to pass through the first eddy current sensor 1 be T i 1 and the time interval for the i-th tooth to pass through the second eddy current sensor 2 be T i 2 ;

[0081] The time interval T for the i-th tooth to pass through the first eddy current sensor 1 i 1 and the time interval T for the i-th tooth to pass through the second eddy current sensor 2 i 2 It is expressed as:

[0082]

[0083] The torsional angular displacement is It is expressed as:

[0084]

[0085] By synthesizing the reference values of each tooth of the test gear 3 and the measured values of the instantaneous moments of each tooth, a torsional angular displacement sequence is obtained

[0086]

[0087] Combined with the time width sequence t i and the torsional vibration angular displacement sequence Plot the torsional angle signal of the shafting;

[0088] Specifically, when the shafting undergoes torsional vibration, the time for each tooth peak and tooth valley of the speed measuring gear to alternately pass by is no longer constant. When the direction of torsional vibration is the same as the direction of shaft rotation within a certain period of time, the speed of the shafting at the operating speed is superimposed with the speed of torsional vibration. At this time, the time for a tooth peak or tooth valley to pass through the measurement area will be less than the passing time in the non-torsional vibration state, and the width of the pulse will decrease; when the direction of torsional vibration of the shafting is opposite to the direction of shaft rotation, the speed of torsional vibration needs to be subtracted from the operating speed of the shafting. At this time, the time for a tooth peak or tooth valley to pass through the measurement area will be greater than the passing time in the non-torsional vibration state, and the width of the pulse will increase; refer to Figure 3 , TH(t) is the high-level time function in the non-torsional vibration state, TL(t) is the low-level time function in the non-torsional vibration state, α TH (t) is the high-level time function in the torsional vibration state, α TL (t) is the low-level time function in the torsional vibration state; thus, the relationship between the pulse width modulation signal and the torsional angle is established. By extracting the time interval α TH (t i ) between two adjacent teeth monitored by the sensor and the time α TL (t i ) of one tooth width monitored by the sensor, the torsional angle signal of the shafting can be obtained.

[0089] Furthermore, in S3, the torsional vibration fault monitoring system includes a main monitoring view real-time interface, a rotational speed and torsional angle real-time interface, a steam turbine life assessment interface, and a historical data interface; the data displayed on the main monitoring view real-time interface includes the one-minute maximum value of rotational speed, the one-minute maximum value of torsional angle, the one-minute maximum value of power, the real-time current of the three-phase motor, the real-time voltage of the three-phase motor, and the external view of the steam turbine, and the change conditions of the above data parameters are displayed in real time, and an alarm prompt is given when the torsional angle parameter is too large; the data displayed on the rotational speed and torsional angle real-time interface includes the real-time data of rotational speed, the real-time data of torsional angle, the real-time data of power, the one-minute maximum value of rotational speed, the one-minute maximum value of torsional angle, the one-minute maximum value of power, and the cumulative occurrence frequencies of power, rotational speed, and torsional angle; the steam turbine life assessment interface highlights the determined dangerous parts, conducts life assessment on them, and displays the remaining life of the dangerous parts; the historical data interface records the torsional vibration fault data and provides safety analysis;

[0090] Specifically, the determined dangerous part is the part where the maximum value of the torsional angle per minute exceeds the standard rated value; the safety analysis includes the judgment and analysis of the failure mode, the determination and analysis of the shafting state, the torsional vibration response analysis, the synthesis analysis of the electromagnetic torque, the torsional vibration model simulation analysis, and the fatigue loss analysis.

[0091] Although the present invention has been described based on a limited number of embodiments, those skilled in the art in this technical field will understand that other embodiments can be envisioned within the scope of the present invention thus described. In addition, it should be noted that the language used in this specification is mainly selected for the purpose of readability and teaching, rather than for the purpose of explaining or limiting the subject matter of the present invention. Therefore, many modifications and variations will be obvious to those of ordinary skill in the art in this technical field without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure of the present invention is illustrative rather than restrictive, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for visual analysis of abnormal torsional vibration of a steam turbine, characterized in that, It includes the following steps: S1. Adopt non-contact measurement, draw a reference signal, and calculate the torsional vibration signal of the shafting; Specifically: S11. Install eddy current sensors and take measures to limit the bending vibration interference; S12. Draw a reference signal according to the principle of torsional vibration information extraction; S13. Calculate the real-time rotational speed of the shafting; S14. Draw the torsional angle signal of the shafting; S2. Collect the unit status parameters; S3. Design a torsional vibration fault monitoring system based on the torsional vibration signal of the shafting and the unit status parameters; In the above S11, the first eddy current sensor and the second eddy current sensor are used. With the vertical central axis of the test gear as the reference, the 180-degree symmetric installation method is adopted to limit the bending vibration interference and monitor the real-time rotational speed of the test gear; In the step S12, according to the torsional vibration information extraction principle: when the shafting does not undergo torsional vibration, the pulse signal output by the sensor is an equal-period pulse; let the reference signal be a non-torsional vibration pulse signal, the pulse number of the reference signal be i, i = 1, 2, 3... n, n is the number of teeth of the test gear, and the time width of the i-th pulse period of the reference signal is t; In S13, based on the angle between two adjacent teeth of the test gear and the angular velocity ω of the shafting rotation, the real-time rotation of the shafting is calculated. i Rotational speed f; Test the angle between two adjacent teeth of the gear Expressed as: The rotational angular velocity ωi of the shafting is expressed as: The real-time rotational speed f of the shafting is expressed as: In S14, when torsional vibration occurs to the rotating shaft, assume that the torsional angular displacement at the position of the i-th tooth of the test gear is such that the torsional angular displacement causes the i-th tooth to pass the first eddy current sensor and the second eddy current sensor before or after is Δt; i Torsional angular displacement The time when the ith tooth passes through the first eddy current sensor and the second eddy current sensor is advanced or delayed by a time Δt i Expressed as: Bending vibration velocity component V y The time when the i-th tooth passes through the first eddy current sensor and the second eddy current sensor is advanced or delayed by a time of Δt′; Bending vibration velocity component V y The time Δt′ by which the passing time of the ith tooth through the first eddy current sensor and the second eddy current sensor is advanced or delayed is expressed as: Where, ω is the angular velocity and R is the radius of the test gear; Let the time interval for the \(i\)-th tooth to pass through the first eddy current sensor be \(T\). i 1 And the time interval for the \(i\)-th tooth to pass through the second eddy current sensor is \(T\). i 2 ; The time interval T when the i-th tooth passes through the first eddy current sensor i 1 and the time interval T when the i-th tooth passes through the second eddy current sensor i 2 are expressed as: The torsional angular displacement is Expressed as: By comprehensively testing the reference values of each tooth of the gear and the measured values at each instantaneous moment of each tooth, a torsional vibration angular displacement sequence is obtained Combine the time width sequence t i and the torsional vibration angular displacement sequence to plot the torsional angle signal of the shafting system.

2. The method for visual analysis of abnormal torsional vibration of a steam turbine according to claim 1, characterized in that, The torsional vibration fault monitoring system includes a main monitoring view real-time interface, a rotational speed and torsional angle real-time interface, a steam turbine life assessment interface, and a historical data interface; the data displayed on the main monitoring view real-time interface includes the one-minute maximum value of the rotational speed, the one-minute maximum value of the torsional angle, the one-minute maximum value of the power, the real-time current of the three-phase motor, the real-time voltage of the three-phase motor, and the external view of the steam turbine, and the changes of the above data parameters are displayed in real time, and an alarm prompt is given when the torsional angle parameter is too large; the data displayed on the rotational speed and torsional angle real-time interface includes the real-time rotational speed data, the real-time torsional angle data, the real-time power data, the one-minute maximum value of the rotational speed, the one-minute maximum value of the torsional angle, the one-minute maximum value of the power, and the cumulative occurrence frequencies of the power, rotational speed, and torsional angle; the steam turbine life assessment interface highlights the determined dangerous parts, conducts life assessment on them, and displays the remaining life of the dangerous parts; the historical data interface records the torsional vibration fault data and provides safety analysis.

Images