Method for analyzing and evaluating cost-reducing and efficiency-increasing performance of additional damping measure of wind power supporting structure

Abstract

The invention relates to a method for analyzing and evaluating cost reduction and efficiency improvement performance of additional damping measures of a wind power support structure, which comprises the following steps of: respectively calculating steel consumption cost of corresponding unit life according to different design schemes; comparing the steel consumption cost of unit life corresponding to different design schemes, and screening out the design scheme with the optimal cost-reducing and efficiency-increasing performance; and performing upper and lower limit estimation of the cost benefit on the screened design scheme by adopting the normalized cost benefit. Compared with the prior art, the method has the advantages that the prolonging effect of the vibration reduction measure on the fatigue life is quantified and is combined with the steel consumption change brought by the vibration reduction measure, the cost-reducing and efficiency-increasing effect is analyzed by calculating the steel cost required by the unit fatigue life, and the steel consumption per unit life is used as an evaluation index; by means of the method, all constraint damping schemes can be compared under the unified scale, redesign of an original tower in the damping scheme comparison and selection stage is avoided, and therefore rapid evaluation and optimization in the scheme design stage are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of cost-benefit analysis of wind power structures, and in particular to a method for analyzing and evaluating the cost-reduction and efficiency-enhancing performance of additional damping measures of a wind power support structure. Background Art

[0002] In recent years, as the global energy structure is undergoing a profound transformation, offshore wind power has become an important part of the clean energy field and has shown a rapid development momentum, among which the trend of large-scale wind power equipment is becoming more and more obvious. However, as the wind power support structure evolves towards higher towers and longer blades, low-frequency excited wind towers are also facing multiple vibration challenges in extreme environments or long-term operation under the requirements of cost reduction and efficiency improvement. Therefore, it is crucial to study effective vibration control technology.

[0003] At present, among many passive control technologies, TMD (Tuned Mass Damper) and TLD (Tuned Liquid Damper) are two key inertia-based control methods. They effectively reduce the vibration of wind turbine structures by installing specific devices on the top of the tower and using the reaction force principle. Although traditional TMD and TLD technologies can reduce the vibration of wind turbine structures to a certain extent, their limitations gradually become apparent when faced with the special requirements of wind turbine support structures for installation space, multi-directional control, and high robustness. To this end, improved TMDs such as RID-TMD (rotating inertia dual tuned mass damper), PS-TMD (prestressed tuned mass damper), PTMD (suspended tuned mass damper) and TMDI (inertial tuned mass damper), as well as various forms of TLDs, such as TLCD (tuned liquid column dampers), TTLCD (toroidal tuned liquid column dampers), and TLCGD (tuned liquid column gas damper), have been proposed and studied one after another. However, inertial-based technology has limitations, such as the control effect on specific actions such as near-field earthquakes may not be ideal. Moreover, due to its inertial-based characteristics, the calculation and analysis need to fully consider various complex working conditions to reflect the objective vibration reduction effect.

[0004] As an important supplement to inertial technology, material-based energy dissipation technology has also received some attention in recent years, and its potential for cost reduction and efficiency improvement has begun to emerge. This type of technology is usually installed at the bottom of the structure, dissipating energy through friction, viscosity, viscoelasticity and other material deformations to provide additional damping for the structure to reduce vibration. Related research includes scissor-jackbraced viscous damper, friction energy dissipation device installed at the bottom of the tower, amplifying damping transfer system, high damping viscoelastic damper, and constrained damping. Material-based energy dissipation technology is expected to effectively make up for the shortcomings of inertial-based solutions in some aspects, such as repairing and extending the life of wind turbine towers or foundations. Machado pointed out that the construction and installation stages of wind power structures account for 32% and 31.5% of their life cycle carbon emissions respectively. This makes the installation location of the material-based solution at the bottom of the structure greatly reduce the cost of measures generated by the installation, especially in the case of retrofitting existing wind turbines. Compared with other material-based energy dissipation solutions, the constrained damping solution is more convenient to implement on the outer periphery of the lower part of the wind tower, and will not cause complex local stress problems, so it has significant advantages in practical applicability. The constrained damping layer uses viscoelastic material as the constrained layer, and the outer layer uses a material with a larger modulus (such as steel) as the constraining layer, which can be applied to the surface of the cylindrical shell structure to provide damping performance. When the wind tower is bent and deformed, the constrained layer produces relative deformation between the base layer and the constraining layer, and then deformation mainly based on shear occurs to consume energy and provide additional damping for the structure.

[0005] Although there are a lot of studies on vibration control of wind turbine structures, previous studies generally only focus on improving the performance of the structure, but not on the cost and constraints of the response. For example, Gao's study revealed the limitations of existing literature in evaluating the control effect of inertial measures such as TMD. By comprehensively considering factors such as the internal space constraints of the tube, the cost-effectiveness ratio, and the adverse effects of TMD and tower forces on fatigue, they found that relying solely on numerical and theoretical methods may overestimate the vibration reduction effect of TMD. In their study, by comprehensively considering these factors, an additional damping ratio of about 1% was successfully achieved, which is much lower than the values ​​in some studies. The reason why existing studies often do not conduct cost-benefit analysis is that the actual design of wind turbine structures is complex; if a reliable cost-benefit evaluation is to be conducted, a lot of working condition analysis needs to be performed after considering the influence of the vibration reduction device, which makes it impossible to simply and reliably conduct a quick evaluation analysis, which is not conducive to accurately and efficiently selecting the optimal solution from multiple vibration reduction design solutions. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a method for analyzing and evaluating the cost-reduction and efficiency-enhancing performance of additional damping measures of wind power support structures. The method adopts the amount of steel used per unit life as an evaluation index, and evaluates the cost-effectiveness of different constrained damping schemes. It can enable the various constrained damping schemes to be compared on a unified scale, and avoids the redesign of the original tower in the damping scheme selection stage, thereby facilitating rapid evaluation and optimization in the scheme design stage.

[0007] The object of the present invention can be achieved by the following technical solution: A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures of a wind power support structure, comprising the following steps:

[0008] S1. Calculate the steel usage cost per unit life for different design schemes;

[0009] S2. Compare the steel usage cost per unit life corresponding to different design schemes, and select the design scheme with the best cost reduction and efficiency improvement performance;

[0010] S3. Using normalized cost-effectiveness, estimate the upper and lower limits of cost-effectiveness for the design solutions screened in step S2.

[0011] Furthermore, the calculation of the steel usage cost per unit life in step S1 specifically includes the following steps:

[0012] S11. Damping influence analysis: By calculating the additional damping, the dynamic coefficient (Dynamic Amplification Factor, DAF) is obtained;

[0013] S12. Wind load spectrum analysis: Analyze the bending moment spectrum at the tower control section caused by pulsating wind loads and evaluate the dynamic effect of wind loads on the structure;

[0014] S13, stress spectrum analysis: calculate the stress spectrum of the dangerous point based on the bending moment spectrum, simplify the stress spectrum into a single-frequency stress spectrum about the fundamental frequency of the wind tower, and calculate the stress amplitude of the constant amplitude stress time history;

[0015] S14. Fatigue life estimation: Combined with the SN (stress amplitude-life) curve of the material, the fatigue life of the structure is estimated;

[0016] S15. Calculation of unit life cost: Divide the steel cost by the estimated fatigue life to obtain the steel cost per unit life.

[0017] Furthermore, the step S11 specifically adopts the modal strain energy method to calculate the additional damping, and then obtains the dynamic coefficient, so as to fully consider the influence of the damping on the structural performance.

[0018] Furthermore, the step S12 includes the following process:

[0019] Considering only the wind load acting on the nose, the wind load acting on RNA (rotor-nacelleassembly) at a given wind speed is:

[0020]

[0021] Among them, ρ a is the air density, A R is the swept area of ​​the impeller, U is the total wind speed, is the average wind speed, u is the pulsating wind speed, C T is the thrust coefficient,

[0022] The power spectrum density of the fluctuating wind speed is obtained by Kaimal spectrum calculation:

[0023]

[0024] Where f is the frequency, σ U is the standard deviation of wind speed U, I is the turbulence intensity, L k is the integration length parameter, z is the distance from sea level;

[0025] The wind load is divided into average wind load (i.e. static load) and fluctuating wind load (i.e. dynamic load). After introducing the fluctuating wind speed spectrum, the fluctuating wind load spectrum is obtained as follows:

[0026]

[0027] Among them, F dyn is the pulsating wind load, is the pulsating wind load spectrum.

[0028] Furthermore, the step S13 includes the following process:

[0029] Under the action of pulsating wind load, the tower and pile foundation will produce dynamic response. The tower pile bending moment response spectrum considering the dynamic coefficient is:

[0030]

[0031] Among them, H is the height of the rotor from the sea level, h is the height of the section from the sea level, and DAF is the dynamic coefficient;

[0032] The structural dynamic response under pulsating wind load only considers the first-order modal contribution, and the wind tower is equivalent to a single-degree-of-freedom system with inertia concentrated at the top of the tower. Its dynamic coefficient is:

[0033]

[0034] Where, β is the frequency ratio, β = f / f0, f0 is the first-order modal frequency of the wind tower, ξ is the first-order modal damping ratio of the wind tower;

[0035] The maximum normal stress spectrum on the section at a distance h from sea level is calculated from the bending moment response spectrum:

[0036]

[0037] Where W is the section bending modulus;

[0038] According to the linear (Airy) wave theory, the stress time history under the action of pulsating wind load is obtained from the stress spectrum through the harmonic superposition method. Since the structural dynamic response under the action of pulsating wind load is mainly concentrated near the first-order modal frequency of the wind tower, in order to facilitate fatigue life assessment, only the main components of the harmonics are retained, and the variable amplitude fatigue problem is simplified to a constant amplitude fatigue problem, that is, only the harmonic components corresponding to the first-order modal frequency of the stress spectrum are retained, and the stress time history is obtained as follows:

[0039] S max,dyn (t) = S0cos(2πf0t)

[0040] Where S is the stress amplitude, is the stress power spectrum function The area in the frequency range of 0.75f0 to 1.25f0.

[0041] Furthermore, the fatigue life estimation formula in step S14 is:

[0042]

[0043] logN=-m log S+C

[0044] Among them, T is the fatigue life in years, N is the number of failure cycles, m is the fatigue strength index of the material, and C is the fatigue limit of the material.

[0045] Furthermore, the steel usage cost per unit life in step S15 is:

[0046]

[0047] in, M is the steel consumption per unit life. total,steel The total steel consumption of wind turbine tower.

[0048] Furthermore, in step S2, the design scheme corresponding to the lowest steel consumption cost per unit life is taken as the design scheme with the best cost reduction and efficiency improvement performance.

[0049] Furthermore, the step S3 specifically performs normalization processing based on the fatigue life and steel consumption of the uncontrolled structure to obtain the normalized fatigue life and unit annual steel consumption, and determines the cost-effectiveness upper limit and cost-effectiveness lower limit of the design scheme by optimizing the parameters of the constrained damping in the design scheme within the preset range of the damping ratio of the uncontrolled structure.

[0050] Furthermore, in step S3, the preset range of the damping ratio of the uncontrolled structure is 1% to 5%. When the damping ratio of the uncontrolled structure is taken as the upper limit of 5%, the corresponding lower limit of the benefit of the constrained damping of the design scheme is obtained; when the damping ratio of the uncontrolled structure is taken as the lower limit of 1%, the corresponding upper limit of the benefit of the constrained damping of the design scheme is obtained.

[0051] Compared with the prior art, the present invention has the following advantages:

[0052] The present invention calculates the corresponding steel consumption cost per unit life for different design schemes, and screens out the design scheme with the best cost reduction and efficiency improvement performance by comparing the steel consumption cost per unit life corresponding to different design schemes. Thus, a cost reduction and efficiency improvement analysis scheme based on the steel consumption cost per unit fatigue life is proposed, and the extension effect of the vibration reduction measures on the fatigue life is quantified and combined with the change in steel consumption brought about by the vibration reduction measures. The cost reduction and efficiency improvement effect is directly judged by calculating the steel cost required per unit fatigue life: if the vibration reduction scheme can significantly reduce the steel consumption cost per unit fatigue life, then its significant advantages in economy and long-term operation reliability are verified. The present invention not only facilitates rapid evaluation in the scheme design stage, but also provides a solid theoretical basis for subsequent optimization design, so that different vibration reduction schemes can be compared under a unified scale benchmark, and also avoids the redesign of the original tower in the damping scheme selection stage, which is beneficial to rapid evaluation and optimization in the scheme design stage.

[0053] When calculating the steel consumption cost per unit life, the present invention comprehensively considers multiple aspects such as damping influence, wind load effect, stress analysis, fatigue life and economic performance, and provides a comprehensive analysis framework for performance optimization and cost reduction of constrained damping structures, including obtaining the stress spectrum at the tower section using the pulsating wind load spectrum, estimating the fatigue life based on the stress spectrum and the fatigue life curve, which can fully ensure the reliability of the steel consumption cost per unit life.

[0054] The present invention utilizes normalized cost-effectiveness to further evaluate the upper and lower limits of the cost-effectiveness of a solution, and can quickly evaluate the upper and lower limits of the cost-effectiveness of a solution, thereby facilitating rapid decision-making at the solution stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0056] Figure 2 It is a schematic diagram of the process of calculating the steel usage cost per unit life for different design schemes in the embodiment;

[0057] Figure 3 is a schematic diagram of stress spectrum density;

[0058] Figure 4a It is a schematic diagram comparing the fatigue life and total steel consumption of each scheme under the condition of uncontrolled modal damping ratio (FA1%, SS1%) in the embodiment;

[0059] Figure 4b 1 is a schematic diagram comparing the normalized fatigue life and unit annual steel consumption of each scheme under the condition of uncontrolled modal damping ratio (FA1%, SS1%) in the embodiment;

[0060] Figure 5a to 5c Schematic diagram of the law of additional damping and cost-effectiveness changing with the thickness t1 of the damping layer and the thickness t2 of the constraining layer in the embodiment;

[0061] Figure 6a It is a schematic diagram of the comparison of normalized fatigue life under the conditions of uncontrolled damping ratio of 5% and uncontrolled damping ratio of 1% in the embodiment;

[0062] Figure 6b It is a schematic diagram comparing the normalized annual steel consumption in the case of an uncontrolled damping ratio of 5% and an uncontrolled damping ratio of 1% in the embodiment. DETAILED DESCRIPTION

[0063] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0064] Example

[0065] like Figure 1 As shown, a method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures of a wind power support structure includes the following steps:

[0066] S1. Calculate the steel usage cost per unit life for different design schemes;

[0067] S2. Compare the steel usage cost per unit life corresponding to different design schemes, and select the design scheme with the best cost reduction and efficiency improvement performance;

[0068] S3. Using normalized cost-effectiveness, estimate the upper and lower limits of cost-effectiveness for the design solutions screened in step S2.

[0069] This embodiment applies the above solution, such as Figure 2 As shown, including:

[0070] 1) Damping influence analysis: First, the additional damping is calculated by the modal strain energy method, and then the dynamic load factor (DAF) is obtained to fully consider the influence of damping on the structural performance.

[0071] 2) Wind load spectrum analysis: Analyze the bending moment spectrum at the tower control section caused by pulsating wind loads to evaluate the dynamic effect of wind loads on the structure.

[0072] 3) Stress spectrum analysis: The stress spectrum of the dangerous point is calculated based on the bending moment spectrum, and the stress spectrum is simplified into a single-frequency stress spectrum about the fundamental frequency of the wind turbine tower. The stress amplitude of the constant amplitude stress time history is calculated to provide basic data for subsequent fatigue life estimation.

[0073] 4) Fatigue life estimation: Combined with the SN curve of the material, a simplified estimate of the fatigue life of the structure is made.

[0074] 5) Calculation of unit life cost: Divide the steel cost by the estimated fatigue life to obtain the steel cost per unit life, which provides a basis for economic performance evaluation.

[0075] 6) Design scheme comparison: Compare the unit life cycle costs of different design schemes to select the design scheme that performs best in terms of cost reduction and efficiency improvement.

[0076] 7) Cost reduction and efficiency improvement effect evaluation: Finally, the entire analysis process is summarized to evaluate the actual effect of the high-strength steel constrained damping structure in reducing the unit life cost, providing guidance for engineering practice.

[0077] The above analysis process framework comprehensively considers multiple aspects such as damping influence, wind load effect, stress analysis, fatigue life and economic performance, and can provide a comprehensive analysis framework for performance optimization and cost reduction of high-strength steel constrained damping structures.

[0078] Specifically, when calculating the pulsating wind load spectrum, under normal operating conditions at rated wind speed, the wind load acting on the nose (RNA) in the FA direction is much greater than the wind load acting on the tower. Therefore, only the wind load acting on the nose is considered in this scheme. The wind load acting on the RNA at a given wind speed can be approximately calculated by the following formula:

[0079]

[0080] Where: a is the air density, take 1.225kg / m 3 ; A R is the swept area of ​​the impeller; U is the total wind speed, is the average wind speed, u is the pulsating wind speed; C T is the thrust coefficient,

[0081] The power spectrum density of fluctuating wind speed can be obtained by Kaimal spectrum calculation:

[0082]

[0083] Where: f is the frequency, σ U is the standard deviation of wind speed U, I is the turbulence intensity, L k is the integration length parameter, z is the distance from sea level.

[0084] The wind load in the above formula is divided into average wind load (static load) and pulsating wind load (dynamic load), and the pulsating wind load can be approximately calculated by the following formula:

[0085]

[0086] After introducing the fluctuating wind speed spectrum, the fluctuating wind load spectrum can be obtained:

[0087]

[0088] Then the structural dynamic response is calculated. Under the action of pulsating wind load, the tower and pile foundation will produce dynamic response. The tower pile bending moment response spectrum considering the dynamic coefficient can be calculated by the following formula:

[0089]

[0090] Where: H is the height of the rotor from the sea level, h is the height of the section from the sea level, and DAF is the Dynamic amplification coefficient.

[0091] The structural dynamic response under pulsating wind loads can only consider the first-order modal contribution. After the wind tower is equivalent to a single-degree-of-freedom system with inertia concentrated at the top of the tower, its dynamic coefficient can be calculated by the following formula:

[0092]

[0093] Where: β is the frequency ratio, β = f / f0, f0 is the first-order modal frequency of the wind tower; ξ is the first-order modal damping ratio of the wind tower.

[0094] The maximum normal stress spectrum on the section at a distance h from sea level can be further calculated from the bending moment response spectrum:

[0095]

[0096] Where: W is the bending modulus of the section.

[0097] According to the linear (Airy) wave theory, the stress time history under pulsating wind load can be obtained from the stress spectrum through the harmonic superposition method. Since the dynamic response of the structure under pulsating wind load is mainly concentrated near the first-order modal frequency of the wind tower, in order to facilitate fatigue life assessment, only the main components of the harmonics are retained to simplify the variable amplitude fatigue problem to a constant amplitude fatigue problem, that is, only the harmonic components corresponding to the first-order modal frequency of the stress spectrum are retained, and the stress time history can be calculated as follows:

[0098] S max,dyn (t) = S0cos(2πf0t)

[0099] Where: S is the stress amplitude, is the stress power spectrum function The area in the frequency range of 0.75f0 to 1.25f0 (such as Figure 3 shown).

[0100] Then, fatigue life prediction and economic evaluation are carried out. Fatigue life prediction is crucial for evaluating the reliability and economy of wind turbines under long-term wind loads. Generally, the wall thickness of the pile tube is often thicker and the design redundancy is higher, so fatigue failure is not easy to occur. For the convenience of discussion, this embodiment only studies the fatigue life of the part of the wind turbine tower above the average sea level, so only the pulsating wind load needs to be considered.

[0101] On the basis of obtaining the constant stress amplitude of the control section, the fatigue life of the wind turbine tower can be quickly calculated according to the SN (stress amplitude-life) relationship of the steel.

[0102] The relationship between fatigue cycle N and stress range S is shown in the following formula:

[0103] logN=-m log S+C

[0104] Among them: m and C are the fatigue parameters of the material. The fatigue parameters of steels with different strengths are shown in Table 1. N is the number of failure cycles.

[0105] Table 1 Fatigue parameters of steel

[0106] Q355 Q460 Q550 Q690 Q960 m 3 3 3 4 4 C 12.449 12.994 13.360 15.564 15.834

[0107] The fatigue life T (year) is calculated as follows:

[0108]

[0109] In order to facilitate the evaluation of the economic efficiency of the wind turbine tower throughout its life cycle, the steel consumption per unit life cycle indicator is introduced. (kg peryear); This indicator takes into account the total construction cost and service life of the wind tower, and can be used as an evaluation indicator to measure the economic efficiency of the wind tower.

[0110]

[0111] Where: M total,steel It is the total steel consumption (kg) of the wind tower including tower tube, pile tube, etc.

[0112] Using the updated modal dynamic magnification factor and stress spectrum, the simplified evaluation section fatigue life is finally obtained, as shown in Table 2. Among them, the high-strength steel constrained damping scheme has improved the fatigue life of the control section to varying degrees. This is because the principle of approximately equal strength replacement is adopted when determining the analysis scheme. Therefore, although the tower wall thickness of the constrained damping section is reduced, the NS curve of high-strength steel shows that it has a better fatigue life, so the final fatigue life control section is not on the high-strength steel section. But at the same time, due to the additional damping of the high-strength steel constrained damping, the dynamic magnification factor under the same wind load is reduced, which ultimately reduces the cyclic stress amplitude.

[0113] Table 2 Fatigue life of cross section and control section

[0114]

[0115]

[0116] In order to further analyze the benefits of high-strength steel constrained damping compared to the uncontrolled solution, this example calculates the steel consumption cost per unit life. Calculations are performed when the high-strength steel solution When it is greater than the original tower, it means that the high-strength steel restrained damping has a positive benefit of reducing costs and increasing efficiency. It is worth noting that for high-strength steel restrained damping, its positive effect is obvious. This is because the corresponding parts of the original tower structure can be replaced by high-strength steel restrained damping sections, achieving an increase in damping without increasing the amount of steel used.

[0117] Plot the annual steel consumption of each scheme under the condition of uncontrolled modal damping ratio (FA1%, SS1%) Total steel consumption (such as Figure 4a As shown in the figure), the fatigue life and steel consumption of the control structure are further used as the benchmark for normalization to obtain the normalized fatigue life and unit annual steel consumption (as shown in the figure). Figure 4b ). Figure 4a It can be seen that the Q460-T30(30)30 scheme can increase the additional damping without causing any change in the amount of steel used, while the other higher-strength high-strength steel schemes can even achieve additional damping on the basis of the original structure while reducing the amount of steel used. This is because the reduction in the high-strength steel cross-section in the high-strength steel constrained damping is greater than the increase in the constrained layer steel in the constrained damping. Figure 4bThe results show that under the design strategy of equal thickness of the constrained layer, constrained damping layer and high-strength steel cylinder wall, as the strength of high-strength steel increases, the normalized annual steel consumption cost decreases significantly, which means that as the amount of high-strength steel increases, the cost reduction and efficiency improvement brought by the high-strength steel constrained damping scheme becomes more and more significant.

[0118] Finally, the upper and lower limits of cost-effectiveness are estimated. Figure 4a and Figure 4b The trend law of high-strength steel constrained damping is described, but it is not enough to describe the potential of high-strength steel constrained damping. On the one hand, the various schemes have not been optimized, so the effect of high-strength steel constrained damping in reducing costs and increasing efficiency has not been fully utilized. On the other hand, since high-strength steel constrained damping directly affects the fatigue life and annual steel consumption cost in a way that affects the additional damping, the relative relationship between the additional damping and the original structural damping will directly affect the cost-effectiveness evaluation. Since the damping cost of the original uncontrolled structure and its value are a complex issue, it is generally believed to be in the range of 1% to 5%. Therefore, the parameters of the optimized high-strength steel constrained damping are calculated for the uncontrolled structure of 1% to 5%, and the influence of the high-strength steel constrained damping on fatigue performance is evaluated. When the damping ratio of the uncontrolled structure is taken as the upper limit of 5%, the lower limit of the benefit of high-strength steel constrained damping can be obtained; and when the damping ratio of the uncontrolled structure is taken as the upper limit of 1%, the upper limit of the benefit of high-strength steel constrained damping can be obtained. It is worth noting that although Q690 and 960 show better damping enhancement, the lower strength Q550 and Q460 grades have relatively more mature application conditions. Therefore, the upper and lower limits of the performance impact of high-strength steel constrained damping are analyzed using Q550 as a representative.

[0119] Based on the Q550-T20(20)20 scheme, assuming that the damping ratio of the uncontrolled structure is 5%, the damping layer t1 and the constraint layer thickness t2 are used as variables, and the modal damping, normalized fatigue life, and normalized annual steel consumption of the Q550 scheme are calculated respectively. Figure 5a to 5c shown. Figure 5a and 5b It is shown that the modal damping ratio and normalized fatigue life decrease with the increase of the damping layer thickness t1, and increase with the increase of the constrained layer thickness t2. For example, when the damping layer thickness is 5 mm and the constrained layer thickness is 5 mm, the scheme Q550-T20(6)26 obtains an additional damping ratio of 0.97% on the basis of the uncontrolled 5% damping ratio. This means that compared with the additional damping ratio of 0.54% of Q550-T20(20)20, a further damping increment of 0.43% can be obtained by adjusting the dimensions of t1 and t2. Figure 5cThe law shows that although increasing t2 will lead to a certain increase in steel consumption, the annual steel consumption cost is reduced due to the contribution of additional damping. The damping improvement effect of the constrained damping scheme is affected by the shear stiffness of the damping layer and the axial stiffness of the constrained layer. Within a certain range, the constrained damping scheme can obtain a better damping improvement effect by increasing the shear stiffness of the damping layer and the axial stiffness of the constrained layer.

[0120] Figure 6a and Figure 6b The cost-effectiveness of the uncontrolled structure damping ratio FA1% and FA5% is compared. Figure 6a is the normalized fatigue life based on the fatigue life of the uncontrolled structure, Figure 6b is the normalized annual steel consumption based on the steel consumption per unit life of the uncontrolled structure, Figure 6a and Figure 6b The upper and lower limits of the impact of the high-strength steel solution on the uncontrolled structure under two uncontrolled structural damping conditions are depicted. The optimization design of adjusting t1 and t2 can further increase the lower limit of the normalized fatigue life and reduce the upper limit of the normalized annual steel consumption.

[0121] The damping ratio is improved by 0.4% to 1.0%, the normalized fatigue life is improved by 14% to 35%, and the normalized annual average steel consumption is reduced by 17% to 27%; therefore, by optimizing the cross-sectional parameters of the high-strength steel segment, the Q550 solution can achieve at least about 35% improvement in fatigue life and 27% reduction in cost.

[0122] In summary, this scheme quantifies the effect of vibration reduction measures on fatigue life extension, and combines it with the change in steel consumption brought about by the vibration reduction measures, and directly evaluates the cost reduction and efficiency improvement effect by calculating the steel cost required per unit fatigue life. If the vibration reduction scheme can significantly reduce the steel cost per unit fatigue life, it verifies its significant advantages in economy and long-term operational reliability. This method not only facilitates rapid evaluation in the scheme design stage, but also provides a solid theoretical basis for subsequent optimization design.

[0123] This scheme can not only compare various constrained damping schemes on a unified scale, but also avoid redesigning the original tower during the damping scheme selection stage, thereby facilitating rapid evaluation and optimization during the scheme design stage. This scheme adopts normalized cost-effectiveness, which can quickly evaluate the upper and lower limits of the scheme cost-effectiveness, facilitating rapid decision-making during the scheme stage.

[0124] This scheme uses the steel consumption per unit life as an evaluation index, and simplifies the cost-effectiveness evaluation under different constrained damping schemes. The experimental comparison results in the examples show that the high-strength steel constrained damping scheme has a lower steel consumption per unit life than the uncontrolled structure and the ordinary constrained damping scheme, and has a significant effect on reducing costs and increasing efficiency for wind power support structures. And as the strength of high-strength steel increases, the cost-reducing and efficiency-increasing effect becomes more significant due to the enhanced synergistic effect of the high-strength steel constrained damping scheme.

Claims

1. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures, characterized in that: The following steps are involved: S1. Calculate the steel usage cost per unit life for different design schemes; S2. Compare the steel usage cost per unit life corresponding to different design schemes, and select the design scheme with the best cost reduction and efficiency improvement performance; S3. Using normalized cost-effectiveness, estimate the upper and lower limits of cost-effectiveness for the design solutions screened in step S2.

2. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 1, characterized in that: The calculation of the steel usage cost per unit life in step S1 specifically includes the following steps: S11. Damping influence analysis: By calculating the additional damping, the dynamic coefficient DAF is obtained; S12. Wind load spectrum analysis: Analyze the bending moment spectrum at the tower control section caused by pulsating wind loads and evaluate the dynamic effect of wind loads on the structure; S13, stress spectrum analysis: calculate the stress spectrum of the dangerous point based on the bending moment spectrum, simplify the stress spectrum into a single-frequency stress spectrum about the fundamental frequency of the wind tower, and calculate the stress amplitude of the constant amplitude stress time history; S14. Fatigue life estimation: Estimate the fatigue life of the structure based on the SN curve of the material; S15. Calculation of unit life cost: Divide the steel cost by the estimated fatigue life to obtain the steel cost per unit life.

3. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 2, characterized in that: The step S11 specifically uses the modal strain energy method to calculate the additional damping, and then obtains the dynamic coefficient, so as to fully consider the influence of the damping on the structural performance.

4. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 2, characterized in that: The step S12 includes the following process: Considering only the wind load acting on the nose, the wind load acting on the RNA wind rotor-nacelle assembly at a given wind speed is: Among them, ρ a is the air density, A R is the swept area of ​​the impeller, U is the total wind speed, is the average wind speed, u is the pulsating wind speed, C T is the thrust coefficient, The power spectrum density of the fluctuating wind speed is obtained by Kaimal spectrum calculation: Where f is the frequency, σ U is the standard deviation of wind speed U, I is the turbulence intensity, L k is the integration length parameter, z is the distance from sea level; The wind load is divided into average wind load (i.e. static load) and fluctuating wind load (i.e. dynamic load). After introducing the fluctuating wind speed spectrum, the fluctuating wind load spectrum is obtained as follows: Among them, F dyn is the pulsating wind load, is the pulsating wind load spectrum.

5. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 4, characterized in that: The step S13 includes the following process: Under the action of pulsating wind load, the tower and pile foundation will produce dynamic response. The tower pile bending moment response spectrum considering the dynamic coefficient is: Among them, H is the height of the rotor from the sea level, h is the height of the section from the sea level, and DAF is the dynamic coefficient; The structural dynamic response under pulsating wind load only considers the first-order modal contribution, and the wind tower is equivalent to a single-degree-of-freedom system with inertia concentrated at the top of the tower. Its dynamic coefficient is: Where, β is the frequency ratio, β = f / f0, f0 is the first-order modal frequency of the wind tower, ξ is the first-order modal damping ratio of the wind tower; The maximum normal stress spectrum on the section at a distance h from sea level is calculated from the bending moment response spectrum: Where W is the section bending modulus; According to the linear (Airy) wave theory, the stress time history under the action of pulsating wind load is obtained from the stress spectrum through the harmonic superposition method. Since the structural dynamic response under the action of pulsating wind load is mainly concentrated near the first-order modal frequency of the wind tower, in order to facilitate fatigue life assessment, only the main components of the harmonics are retained, and the variable amplitude fatigue problem is simplified to a constant amplitude fatigue problem, that is, only the harmonic components corresponding to the first-order modal frequency of the stress spectrum are retained, and the stress time history is obtained as follows: S max,dyn (t)=S0cos(2πf0t) Where S is the stress amplitude, is the stress power spectrum function The area in the frequency range of 0.75f0 to 1.25f0.

6. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 5, characterized in that: The fatigue life estimation formula in step S14 is: logN=-m log S+C Among them, T is the fatigue life in years, N is the number of failure cycles, m is the fatigue strength index of the material, and C is the fatigue limit of the material.

7. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 6, characterized in that: The steel consumption cost per unit life in step S15 is: in, M is the steel consumption per unit life. total,steel The total amount of steel used in wind turbine towers.

8. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 2, characterized in that: In the step S2, specifically, the design scheme corresponding to the lowest steel consumption cost per unit life is taken as the design scheme with the best cost reduction and efficiency improvement performance.

9. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 8, characterized in that: The step S3 specifically performs normalization based on the fatigue life and steel consumption of the uncontrolled structure to obtain the normalized fatigue life and unit annual steel consumption, and determines the cost-effectiveness upper limit and the cost-effectiveness lower limit of the design scheme by optimizing the parameters of the constrained damping in the design scheme within the preset range of the damping ratio of the uncontrolled structure.

10. A method for analyzing and evaluating the cost reduction and efficiency improvement performance of additional damping measures for wind power support structures according to claim 9, characterized in that: In step S3, the preset range of the damping ratio of the uncontrolled structure is 1% to 5%. When the damping ratio of the uncontrolled structure is taken as the upper limit of 5%, the corresponding lower limit of the benefit of the constrained damping of the design scheme is obtained; when the damping ratio of the uncontrolled structure is taken as the lower limit of 1%, the corresponding upper limit of the benefit of the constrained damping of the design scheme is obtained.

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