Method for evaluating fatigue damage and service life of tower drum of wind turbine generator

Abstract

The invention discloses a wind turbine generator tower drum fatigue damage and life evaluation method, and particularly relates to the technical field of wind turbine generator detection. Fatigue damage and fatigue life of a wind turbine generator tower drum model are analyzed and calculated, and meanwhile, corresponding strain sensors and acceleration sensors are installed on the surface of an actual wind turbine generator tower drum; the data are transmitted to a computer through a strain sensor and an acceleration sensor to be calculated, the stress, deformation and vibration conditions of the wind turbine generator tower in the operation process are obtained, calculation is repeated at certain time intervals, then calculation results are stored in the computer, and meanwhile an equal-proportion wind turbine generator tower model is manufactured. According to the method, the wind turbine generator tower model is put into the air duct, the load stress condition of the wind turbine generator tower model is analyzed and calculated, finally, three groups of analysis results are summarized and compared, a calculation model in a computer is adjusted and optimized, and the accuracy of computer analysis and calculation is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine detection, and more particularly to a method for evaluating fatigue damage and life of a wind turbine tower. Background Art

[0002] The wind turbine tower, as the main supporting structure of the wind turbine, connects all parts of the wind turbine and keeps it stably suspended at high altitudes. It bears the weight of the nacelle, blades, etc., ensuring the stable operation of the entire wind turbine. The outer and inner walls of the wind turbine tower protect the cables, electrical equipment, and other components inside from harsh environmental conditions such as ultraviolet rays, rain, snow, wind and sand, and day and night temperature differences. The wind turbine tower is subjected to complex alternating loads such as wind and blade rotation for a long time, which can easily cause fatigue damage. If not evaluated and monitored, it may cause cracks and deformation in the tower structure. In severe cases, it may even collapse, causing serious harm to personnel and equipment. The wind turbine tower is a key supporting structure of the wind turbine. Fatigue damage to the wind turbine tower will affect the overall stability and reliability of the wind turbine. Through evaluation and monitoring, potential safety hazards can be discovered in a timely manner, and appropriate measures can be taken to repair or reinforce it to ensure the stable operation of the wind turbine. At the same time, by evaluating the fatigue damage and life of the tower, a reasonable maintenance plan can be formulated in advance to avoid large-scale repairs or replacements after serious damage to the tower, thereby reducing maintenance costs.

[0003] Existing methods for evaluating fatigue damage and life of wind turbine towers generally use data models to analyze and calculate wind turbine towers. During the calculation process, multiple sets of data are generally analyzed and calculated, and then the analysis and calculation results are summarized and the average value is taken. Analyzing and calculating multiple sets of data requires a lot of analysis and calculation time, making it difficult to timely evaluate the fatigue damage and fatigue life of wind turbine towers. Since the analysis and calculation are performed under the same data model, the results obtained will not have too large an error, which can easily lead to a large error between the calculated results and the actual results when evaluating the fatigue damage and fatigue life of the wind turbine tower, causing damage to the actual wind turbine tower and leading to accidents. Therefore, improvements are needed. Summary of the Invention

[0004] In order to overcome the above-mentioned defects, the present invention provides a method for evaluating fatigue damage and life of a wind turbine tower. The technical problem to be solved by the present invention is that the existing method for evaluating fatigue damage and life of a wind turbine tower generally analyzes and calculates the wind turbine tower through a data model. During the calculation process, generally after analyzing and calculating multiple sets of data, the analysis and calculation results are summarized and the average value is taken. The analysis and calculation of multiple sets of data requires a lot of analysis and calculation time, which makes it difficult to timely evaluate the fatigue damage and fatigue life of the wind turbine tower. Since the analysis and calculation are performed under the same data model, the results obtained will not have too large an error, which can easily lead to a large error between the calculated result and the actual result when evaluating the fatigue damage and fatigue life of the wind turbine tower, causing damage to the actual wind turbine tower and leading to accidents.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for evaluating fatigue damage and life of a wind turbine tower, comprising the following steps:

[0006] Establish a wind turbine tower model;

[0007] Load analysis, pressure distribution and stress analysis;

[0008] Fatigue damage and fatigue life calculation;

[0009] Real-time data collection;

[0010] Simulation test data collection;

[0011] Analyze, compare and adjust.

[0012] As a further solution of the present invention: the load force analysis includes analyzing the load force of the wind turbine tower model under its own weight according to the shape and material of the wind turbine tower model;

[0013] The calculation formula for the wind turbine tower model's deadweight is: G = ρ s gV s , where ρ s is the density of the wind turbine tower material, V s is the volume of the wind turbine tower, g is the acceleration due to gravity;

[0014] The load calculation formula for the wind turbine tower model is: Where F is the load acting on the wind turbine tower, ρ is the air density, ν is the wind speed, A is the windward area of the wind turbine tower, C d is the drag coefficient;

[0015] The pressure distribution and stress analysis includes calculating the pressure distribution and stress on the surface of the wind turbine tower according to the environment around the wind turbine tower;

[0016] The calculation formula for the surface pressure distribution of the wind turbine tower is: Where p is the pressure at a certain point on the surface of the wind turbine tower, ρ is the air density, v is the wind speed, C P is the pressure coefficient.

[0017] As a further solution of the present invention, the fatigue damage and fatigue life calculation includes establishing a mathematical model for fatigue damage and fatigue life assessment of a wind turbine tower load test by combining the load stress conditions of the wind turbine tower model with the pressure distribution and stress conditions on the surface of the wind turbine tower model;

[0018] The fatigue damage assessment formula of the wind turbine tower model is: Where D is fatigue damage, n i is the number of stress cycles of the ith i is the fatigue life corresponding to the i-th stress cycle;

[0019] The fatigue life assessment formula of the wind turbine tower model is: Where N is fatigue life and D is fatigue damage.

[0020] As a further solution of the present invention, the real-time data acquisition includes installing a strain sensor and an acceleration sensor on the wind turbine tower to monitor the force, deformation and vibration of the wind turbine tower in real time during operation, and recording the monitoring data of the wind turbine tower during actual operation at the same time intervals;

[0021] The force calculation formula for the wind turbine tower during operation is: σ = Eε. The strain sensor reflects the force situation by measuring the strain change of the wind turbine tower when it is under force. According to Hooke's law, within the elastic range, the stress and strain of an object are proportional, where σ is stress, E is elastic modulus, and ε is strain. By measuring strain ε and knowing the elastic modulus E of the wind turbine tower material, the stress σ can be calculated, and then the force situation of the wind turbine tower during operation can be obtained.

[0022] The deformation calculation formula of the wind turbine tower during operation is: ΔL=LΔε. A strain sensor is installed in a certain direction of the wind turbine tower, and the strain change in that direction is measured as Δε. The relationship between the strain and deformation in that direction is known to be: Where ΔL is the length change and L is the original length;

[0023] The vibration monitoring calculation method for the wind turbine tower during operation is as follows: for an acceleration sensor installed on the wind turbine tower, the measured acceleration signal is a(t), which is integrated once to obtain the velocity signal v(t) = ∫a(t)dt + v0, where v0 is the initial velocity, and then the velocity signal is integrated once to obtain the displacement signal x(t) = ∫v(t)dt + x0, where x0 is the initial displacement, so as to fully understand the vibration characteristics of the wind turbine tower.

[0024] As a further embodiment of the present invention, the simulation test data collection includes placing a scaled model of a wind turbine tower in a wind tunnel, simulating working conditions of different wind speeds and directions, and measuring the pressure distribution and stress on the surface of the wind turbine tower model;

[0025] The calculation formula for the deadweight of the wind turbine tower scaling model is: G = ρ s gV s , where ρ s is the density of the wind turbine tower scaling mold material, V s is the volume of the scaled model of the wind turbine tower, and g is the acceleration of gravity;

[0026] The load calculation formula for the wind turbine tower scaling model is: Where F is the load acting on the scaled module of the wind turbine tower, ρ is the air density, ν is the wind speed, A is the windward area of the scaled module of the wind turbine tower, C d is the drag coefficient;

[0027] The calculation formula for the surface pressure distribution of the wind turbine tower scaled model is: Where p is the pressure at a certain point on the scaled model surface of the wind turbine tower, ρ is the air density, v is the wind speed, C P is the pressure coefficient.

[0028] As a further solution of the present invention: the analysis and comparison includes comparing the recorded real-time data of the wind turbine tower with the simulation test data and the model calculation results, so as to further verify the accuracy of the model, and timely adjust and optimize the model according to the comparison between the actual operation of the wind turbine tower and the model calculation results, so that the calculation results of the wind turbine tower in the computer are consistent with the fatigue damage and fatigue life of the actual wind turbine tower under the operating state, thereby improving the accuracy of the computer analysis and calculation.

[0029] As a further solution of the present invention: the evaluation and prediction includes inputting the wind speed conditions of the environment surrounding the wind turbine in a specific time period in the future into a computer model according to the weather forecast, performing analysis and calculation, and predicting the fatigue damage and life of the wind turbine tower, so as to provide early warning of the fatigue damage and life of the wind turbine tower, timely inspect and reinforce the wind turbine tower, and at the same time persuade staff to evacuate the area around the wind turbine tower in a hurry to reduce the occurrence of accidents.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention establishes a wind turbine tower model in the calculation, applies formulas to simulate and analyze the load and force analysis, pressure distribution and force analysis at a certain position on the surface of the wind turbine tower model, and then analyzes and calculates the fatigue damage and fatigue life of the wind turbine tower model based on the calculation results. At the same time, corresponding strain sensors and acceleration sensors are installed on the surface of the actual wind turbine tower, and the strain sensors and acceleration sensors are transmitted to the computer for calculation to obtain the force, deformation and vibration conditions of the wind turbine tower during operation. The calculation is repeated at regular intervals, and the calculation results are stored in the computer. At the same time, a proportional wind turbine tower model is manufactured, the wind turbine tower model is placed in the wind tube, and the load and force conditions of the wind turbine tower model are analyzed and calculated. Finally, the three groups of analysis results are summarized and compared, and the calculation model in the computer is adjusted and optimized to improve the accuracy of the computer analysis and calculation.

[0032] 2. The present invention inputs the wind speed conditions of the future time period obtained from the weather forecast into a computer with a wind turbine tower model, and calculates the load pressure conditions, pressure distribution, and force conditions of the wind turbine tower model, thereby calculating the fatigue damage and fatigue life of the wind turbine tower model, ensuring that the calculated fatigue damage and fatigue life are within a safe range, and issuing a timely warning when the fatigue damage and fatigue life exceed the safe range to avoid accidents. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] The present invention provides a method for evaluating fatigue damage and life of a wind turbine tower, comprising the following steps:

[0035] Establish a wind turbine tower model;

[0036] Load analysis, pressure distribution and stress analysis;

[0037] Fatigue damage and fatigue life calculation;

[0038] Real-time data collection;

[0039] Simulation test data collection;

[0040] Analyze, compare and adjust.

[0041] Load analysis includes analyzing the load of the wind turbine tower model under its own weight according to its shape and material.

[0042] The calculation formula for the wind turbine tower model's deadweight is: G = ρ s gV s , where ρ s is the density of the wind turbine tower material, V s is the volume of the wind turbine tower, g is the acceleration due to gravity;

[0043] The load calculation formula for the wind turbine tower model is: Where F is the load acting on the wind turbine tower, ρ is the air density, ν is the wind speed, A is the windward area of the wind turbine tower, C d is the drag coefficient;

[0044] Pressure distribution and stress analysis includes calculating the pressure distribution and stress on the surface of the wind turbine tower based on the environment around the wind turbine tower;

[0045] The calculation formula for the surface pressure distribution of the wind turbine tower is: Where p is the pressure at a certain point on the surface of the wind turbine tower, ρ is the air density, v is the wind speed, C P is the pressure coefficient.

[0046] Fatigue damage and fatigue life calculations involve combining the load and stress conditions of the wind turbine tower model with the pressure distribution and stress conditions on the surface of the wind turbine tower model to establish a mathematical model for fatigue damage and fatigue life assessment during wind turbine tower load testing.

[0047] The fatigue damage assessment formula of the wind turbine tower model is: Where D is fatigue damage, n i is the number of stress cycles of the ith i is the fatigue life corresponding to the i-th stress cycle;

[0048] The fatigue life assessment formula of the wind turbine tower model is: Where N is fatigue life and D is fatigue damage.

[0049] Real-time data collection involves installing strain sensors and acceleration sensors on the wind turbine tower to monitor the force, deformation, and vibration of the wind turbine tower in real time during operation. The monitoring data of the wind turbine tower during actual operation is recorded at regular intervals.

[0050] The force calculation formula for the wind turbine tower during operation is: σ = Eε. The strain sensor reflects the force situation by measuring the strain change of the wind turbine tower when it is under force. According to Hooke's law, within the elastic range, the stress and strain of an object are proportional, where σ is stress, E is elastic modulus, and ε is strain. By measuring strain ε and knowing the elastic modulus E of the wind turbine tower material, the stress σ can be calculated, and then the force situation of the wind turbine tower during operation can be obtained.

[0051] The deformation calculation formula of the wind turbine tower during operation is: ΔL=LΔε. A strain sensor is installed in a certain direction of the wind turbine tower, and the strain change in that direction is measured as Δε. The relationship between the strain and deformation in that direction is known to be: Where ΔL is the length change and L is the original length;

[0052] The vibration monitoring calculation method for the wind turbine tower during operation is as follows: for an acceleration sensor installed on the wind turbine tower, the measured acceleration signal is a(t), which is integrated once to obtain the velocity signal v(t) = ∫a(t)dt + v0, where v0 is the initial velocity, and then the velocity signal is integrated once to obtain the displacement signal x(t) = ∫v(t)dt + x0, where x0 is the initial displacement, so as to fully understand the vibration characteristics of the wind turbine tower.

[0053] The simulation test data collection includes placing a scaled model of the wind turbine tower in a wind tunnel, simulating working conditions of different wind speeds and directions, and measuring the pressure distribution and stress on the surface of the wind turbine tower model;

[0054] The calculation formula for the deadweight of the wind turbine tower scaling model is: G = ρ s gV s , where ρ s is the density of the wind turbine tower scaling mold material, V s is the volume of the scaled model of the wind turbine tower, and g is the acceleration of gravity;

[0055] The load calculation formula of the wind turbine tower scaling model is: Where F is the load acting on the scaled module of the wind turbine tower, ρ is the air density, ν is the wind speed, A is the windward area of the scaled module of the wind turbine tower, C d is the drag coefficient;

[0056] The calculation formula for the surface pressure distribution of the wind turbine tower scaled model is: Where p is the pressure at a certain point on the scaled model surface of the wind turbine tower, ρ is the air density, v is the wind speed, C P is the pressure coefficient.

[0057] The analysis and comparison includes comparing the recorded real-time data of the wind turbine tower with the simulation test data and the model calculation results, so as to further verify the accuracy of the model, and timely adjust and optimize the model according to the comparison between the actual operation of the wind turbine tower and the model calculation results, so that the calculation results of the wind turbine tower in the computer are consistent with the fatigue damage and fatigue life of the actual wind turbine tower under the operating state, thereby improving the accuracy of the computer analysis and calculation.

[0058] The assessment and prediction includes inputting the wind speed conditions of the environment around the wind turbine in a specific time period in the future into a computer model based on the weather forecast, performing analysis and calculations, and predicting the fatigue damage and life of the wind turbine tower, so as to provide early warning of the fatigue damage and life of the wind turbine tower, timely inspect and reinforce the wind turbine tower, and at the same time persuade staff to evacuate the area around the wind turbine tower in a hurry to reduce the occurrence of accidents.

[0059] The working principle of the present invention is:

[0060] Input specific wind speed data into the computer with the wind turbine tower model, perform calculations, and obtain the load stress conditions, pressure distribution, and stress analysis at different positions of the wind turbine tower model under specific wind speed regulation. Calculate the fatigue damage and fatigue life of the wind turbine tower model in the computer model through the obtained load stress conditions, pressure distribution, and stress analysis. Transmit the obtained fatigue damage and fatigue life data to the designated computer for storage. At the same time, install strain sensors and acceleration sensors at specific positions on the surface of the actual wind turbine tower. Analyze and record the stress, deformation, and vibration conditions of the actual wind turbine tower during operation. Then transmit the analysis data to the computer for The wind turbine tower model is stored in a wind tunnel and the wind speed in the wind tunnel is controlled to be the same as the wind speed data input into the computer with the wind turbine tower model for calculation, so as to calculate the load stress, pressure distribution and stress analysis of the wind turbine tower in the wind tunnel, summarize the calculated data, compare them synchronously, adjust the calculation method of the computer with the wind turbine tower model to make the three sets of data consistent, and then input the wind speed of the future time period into the computer with the wind turbine tower model according to the weather forecast, predict the fatigue damage and fatigue life of the wind turbine tower, give early warning, and persuade the staff to evacuate in time to avoid accidents.

[0061] Finally, a few points should be explained: Although the present invention has been described in detail above with general descriptions and specific embodiments, on the basis of the present invention, the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution of the embodiments of the present invention.

Claims

1. A method for evaluating fatigue damage and life of a wind turbine tower, characterized in that: The following steps are involved: Establish a wind turbine tower model; Load analysis, pressure distribution and stress analysis; Fatigue damage and fatigue life calculation; Real-time data collection; Simulation test data collection; Analyze, compare and adjust; Evaluate the predictions.

2. A wind turbine tower fatigue damage and life assessment method according to claim 1, characterized in that: The load analysis includes analyzing the load of the wind turbine tower model under its own weight according to the shape and material of the wind turbine tower model; The calculation formula for the wind turbine tower model's deadweight is: G = ρ s gV s , where ρ s is the density of the wind turbine tower material, V s is the volume of the wind turbine tower, g is the acceleration due to gravity; The load calculation formula for the wind turbine tower model is: Where F is the load acting on the wind turbine tower, ρ is the air density, ν is the wind speed, A is the windward area of the wind turbine tower, C d is the drag coefficient; The pressure distribution and stress analysis includes calculating the pressure distribution and stress on the surface of the wind turbine tower according to the environment around the wind turbine tower; The calculation formula for the surface pressure distribution of the wind turbine tower is: Where p is the pressure at a certain point on the surface of the wind turbine tower, ρ is the air density, v is the wind speed, C P is the pressure coefficient.

3. The wind turbine tower fatigue damage and life assessment method according to claim 1, characterized in that: The fatigue damage and fatigue life calculation includes combining the load stress condition of the wind turbine tower model with the pressure distribution and stress condition on the surface of the wind turbine tower model to establish a fatigue damage and fatigue life assessment mathematical model for the wind turbine tower load test; The fatigue damage assessment formula of the wind turbine tower model is: Where D is fatigue damage, n i is the number of stress cycles of the ith i is the fatigue life corresponding to the i-th stress cycle; The fatigue life assessment formula of the wind turbine tower model is: Where N is fatigue life and D is fatigue damage.

4. A wind turbine tower fatigue damage and life assessment method according to claim 1, characterized in that: The real-time data acquisition includes installing a strain sensor and an acceleration sensor on the wind turbine tower to monitor the force, deformation and vibration of the wind turbine tower in real time during operation, and recording the monitoring data of the wind turbine tower during actual operation at the same time intervals; The force calculation formula for the wind turbine tower during operation is: σ = Eε. The strain sensor reflects the force situation by measuring the strain change of the wind turbine tower when it is under force. According to Hooke's law, within the elastic range, the stress and strain of an object are proportional, where σ is stress, E is elastic modulus, and ε is strain. By measuring strain ε and knowing the elastic modulus E of the wind turbine tower material, the stress σ can be calculated, and then the force situation of the wind turbine tower during operation can be obtained. The deformation calculation formula of the wind turbine tower during operation is: ΔL=LΔε. A strain sensor is installed in a certain direction of the wind turbine tower, and the strain change in that direction is measured as Δε. The relationship between the strain and deformation in that direction is known to be: Where ΔL is the length change and L is the original length; The vibration monitoring calculation method for the wind turbine tower during operation is as follows: for an acceleration sensor installed on the wind turbine tower, the measured acceleration signal is a(t), which is integrated once to obtain the velocity signal v(t) = ∫a(t)dt + v0, where v0 is the initial velocity, and then the velocity signal is integrated once to obtain the displacement signal x(t) = ∫v(t)dt + x0, where x0 is the initial displacement, so as to fully understand the vibration characteristics of the wind turbine tower.

5. The wind turbine tower fatigue damage and life assessment method according to claim 1, characterized in that: The simulation test data collection includes placing a scaled model of the wind turbine tower in a wind tunnel, simulating working conditions of different wind speeds and directions, and measuring the pressure distribution and stress conditions on the surface of the wind turbine tower model; The calculation formula for the deadweight of the wind turbine tower scaling model is: G = ρ s gV s , where ρ s is the density of the wind turbine tower scaling mold material, V s is the volume of the scaled model of the wind turbine tower, and g is the acceleration of gravity; The load calculation formula for the wind turbine tower scaling model is: Where F is the load acting on the scaled module of the wind turbine tower, ρ is the air density, ν is the wind speed, A is the windward area of the scaled module of the wind turbine tower, C d is the drag coefficient; The calculation formula for the surface pressure distribution of the wind turbine tower scaled model is: Where p is the pressure at a certain point on the scaled model surface of the wind turbine tower, ρ is the air density, v is the wind speed, C P is the pressure coefficient.

6. A wind turbine tower fatigue damage and life assessment method according to claim 1, characterized in that: The analysis and comparison includes comparing the recorded real-time data of the wind turbine tower with the simulation test data and the model calculation results, so as to further verify the accuracy of the model, and timely adjust and optimize the model according to the comparison between the actual operation of the wind turbine tower and the model calculation results, so that the calculation results of the wind turbine tower in the computer are consistent with the fatigue damage and fatigue life of the actual wind turbine tower under the operating state, thereby improving the accuracy of the computer analysis and calculation.

7. The method for evaluating fatigue damage and life of a wind turbine tower according to claim 1, wherein: The assessment and prediction includes inputting the wind speed conditions of the environment surrounding the wind turbine in a specific time period in the future into a computer model based on weather forecast conditions, performing analysis and calculations, and predicting the fatigue damage and life of the wind turbine tower, thereby providing early warning of the fatigue damage and life of the wind turbine tower, timely inspecting and reinforcing the wind turbine tower, and at the same time persuading staff to evacuate the area around the wind turbine tower in a hurry to reduce the occurrence of accidents.

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