Dangerous working condition identification and extraction method based on load time sequence

Abstract

The invention discloses a dangerous working condition identification and extraction method based on a load time sequence, relates to the field of dangerous load identification and extraction, and aims at a bearing seat of a wind turbine generator, hot spot stress is obtained by using a hot spot stress method, combining a load time sequence and a hot spot stress influence matrix and adopting a linear superposition method and a Mi ses theory; therefore, the time sequence of the load is converted into a time-stress sequence, the maximum stress moment is screened according to the time-stress sequence under all working conditions, the load at the maximum stress moment is extracted to carry out strength analysis under the corresponding working condition, strength analysis results are compared, identification and extraction of the working condition, time and load at the most dangerous moment are obtained, and the accuracy of strength analysis is improved. The method can be used for strength analysis of the wind turbine generator bearing pedestal structural member, and technical support is provided for subsequent lightweight design of a large-scale wind turbine generator.

Description

Technical Field

[0001] The present invention relates to the field of dangerous load identification and extraction, and in particular to a method for identifying and extracting dangerous working conditions based on load time series. Background Art

[0002] In the field of wind power, the purpose of load simulation is to ensure the safety and reliability of wind turbines under various operating conditions. Currently, the simulation usually conducts fatigue analysis, such as the "Fatigue Analysis Method and Fatigue Analysis Device for Structural Components in Wind Turbines" disclosed in the publication number CN104573172A; another example is the "Fatigue Analysis Method for the Support Structure of Offshore Wind Turbines" disclosed in the publication number CN116738783A; there is little analysis of the most dangerous stress moment.

[0003] Currently, the method for analyzing the most dangerous stress moment usually uses the time domain method for load simulation. There are many load time series in the full working conditions. Currently, the industry mostly uses the extreme value method to extract the load, that is, using a single variable load to judge, and identifying the most dangerous working condition through the maximum and minimum value methods.

[0004] This method may have a situation where the combined load is relatively large, but the single load is not large, resulting in the inability to identify the most dangerous load and moment in the full working conditions. Summary of the Invention

[0005] The purpose of the present invention is to: in view of the above problems, provide a method for identifying and extracting dangerous working conditions based on load time series, which can accurately identify the load at the most dangerous stress moment and effectively extract the load, and can be used for the strength analysis of the bearing seat structural components of wind turbines, providing technical support for the subsequent lightweight design of large wind turbines.

[0006] The technical solution adopted by the present invention is as follows: A method for identifying and extracting dangerous working conditions based on load time series, comprising the following steps:

[0007] S1: For the bearing seat of the wind turbine, calculate the hot spot stress influence matrix under unit load. The load is divided into two cases: positive direction and negative direction. The unit load usually has 6 load components and 1 pre-tightening constant term;

[0008] S2: According to the time series and positive and negative directions of the load, linearly superimpose the coefficients in the hot spot stress influence matrix to obtain the six hot spot stress components;

[0009] S3: Calculate the hot spot stress at all moments to obtain the time-stress series corresponding to the load time series;

[0010] S4: Repeat steps S1 - S3 for each working condition, and transform the time series of the full - working - condition download load into a time - stress series;

[0011] S5: In the time - stress series of each working condition, screen the moment of the maximum stress, extract the load at the moment of the maximum stress for strength analysis under the corresponding working condition, compare the strength analysis results, and obtain the identification and extraction of the working condition, time, and load at the most dangerous moment.

[0012] Furthermore, in step S1, use finite - element software to calculate the hot - spot stress influence matrix under unit load.

[0013] Furthermore, in step S2, select the positive - direction coefficient for the positive - direction load and the negative - direction coefficient for the negative - direction load, and finally obtain the stress influence matrix at this load moment.

[0014] Furthermore, in step S2, take the absolute - value processing of the components of the load, and then multiply by the hot - spot stress influence matrix at the corresponding moment of the load to obtain the six hot - spot stress components.

[0015] Furthermore, the components of the load include six load components and one pre - tightening constant term.

[0016] Furthermore, in step S3, it includes step S31:

[0017] According to the six hot - spot stress components, use the Mises theory to obtain the hot - spot stress σ at this moment; that is:

[0018]

[0020] where: σ is the stress; τ is the shear force; x, y, z are the directions where the stress is located; xy, zx, yz are the planes where the shear force is located.

[0021] Furthermore, in step S3, it includes step S32:

[0022] Repeat steps S1 - S31 to obtain the hot - spot stress σ at all moments under this working condition, and obtain the time - stress series.

[0023] Furthermore, in step S5, during strength analysis, load the load at the moment of the maximum stress extracted for each working condition into the finite - element model for strength analysis.

[0024] In summary, due to the adoption of the above - mentioned technical solutions, the beneficial effects of the present invention are:

[0025] The present invention utilizes the hot spot stress method, combines the time series of loads and the hot spot stress influence matrix, and adopts the linear superposition method and the Mises theory to obtain the hot spot stress, thereby realizing the conversion of the time series of loads into a time-stress series. According to the time-stress series under all working conditions, the moment of the maximum stress is screened, and the load at the moment of the maximum stress is extracted for strength analysis under the corresponding working conditions. By comparing the strength analysis results, the identification and extraction of the working condition, time, and load at the most dangerous moment are obtained, realizing the identification and extraction of the dangerous moment of the bearing seat of a wind turbine, which can be used for the strength analysis of the structural components of the bearing seat of a wind turbine, providing technical support for the subsequent lightweight design of large wind turbines. Description of the Drawings

[0026] The present invention will be described by way of examples with reference to the drawings, where:

[0027] Figure 1 is the flowchart of the present invention. Detailed Embodiments

[0028] In the description of this specification, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this specification is usually placed during use. It is only for the convenience of describing this specification and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this specification.

[0029] In addition, in the description of this specification, if terms such as "horizontal" and "vertical" are used, it does not mean that the components are required to be absolutely horizontal or hanging vertically, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0030] In the description of this specification, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components.

[0031] Embodiment 1

[0032] As Figure 1 shown, a method for identifying and extracting dangerous working conditions based on the time series of loads includes the following steps:

[0033] S1: For the bearing housing of a wind turbine, use finite element software to calculate the hot spot stress influence matrix under unit load. The load has two cases: positive direction and negative direction. The unit load usually has 6 load components and 1 pre-tightening constant term.

[0034] S2: According to the time series and positive / negative directions of the load, linearly superimpose the coefficients in the hot spot stress influence matrix to obtain the six hot spot stress components.

[0035] Specifically, select the coefficients in the positive direction for the load in the positive direction and the coefficients in the negative direction for the load in the negative direction, and finally obtain the stress influence matrix at this load moment.

[0036] Take the absolute value of the load components, and then multiply by the hot spot stress influence matrix at the corresponding moment of the load to obtain the six hot spot stress components. The load components include 6 load components and 1 pre-tightening constant term.

[0037] S3: Calculate the hot spot stress at all moments under the current working condition to obtain the time-stress sequence corresponding to the time series of the load. Specifically, step S3 is divided into two steps. The first is to obtain the hot spot stress σ at a certain moment. The second is to obtain the hot spot stress at all moments under the current working condition in the same way as the first.

[0038] Specifically, in step S3, it includes step S31:

[0039] According to the six hot spot stress components, use the Mises theory to obtain the hot spot stress σ at this moment. That is:

[0040]

[0041] Where: σ is the stress; τ is the shear force; x, y, z are the directions where the stress is located; xy, zx, yz are the planes where the shear force is located.

[0042] Furthermore, in step S3, it includes step S32:

[0043] Repeat steps S1 - S31 to obtain the hot spot stress σ at all moments under this working condition, that is, obtain the time-stress sequence.

[0044] S4: Repeat steps S1 - S3 for each working condition to transform the time series of the load under the full working conditions into a time-stress sequence.

[0045] S5: In the time-stress sequence of each working condition, screen the moment of the maximum stress, and extract the load at the moment of the maximum stress for strength analysis under the corresponding working condition. During strength analysis, load the load at the moment of the maximum stress extracted from each working condition into the finite element model for strength analysis. Compare the strength analysis results to obtain the identification and extraction of the working condition, time, and load at the most dangerous moment.

[0046] In summary, this method avoids the drawbacks of the load extreme value method, does not miss the moment when the combined stress is the largest, takes into account the combined contributions of load variables in six degrees of freedom directions, uses the hot spot stress method, combines the time series of loads and the hot spot stress influence matrix, and adopts the linear superposition method and the Mises theory to obtain the hot spot stress, so as to realize the transformation of the time series of loads into a time-stress series. According to the time-stress series under all working conditions, the moment of the maximum stress is screened, and the load at the moment of the maximum stress is extracted for strength analysis under the corresponding working conditions. By comparing the strength analysis results, the identification and extraction of the working condition, time, and load at the most dangerous moment are obtained, realizing the identification and extraction of the dangerous moment of the bearing seat of the wind turbine, which can be used for the strength analysis of the structural components of the bearing seat of the wind turbine and provides technical support for the subsequent lightweight design of large wind turbines.

[0047] The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new feature or any new combination disclosed in this specification, as well as any new method or process step or any new combination disclosed.

Claims

1. A method for identifying and extracting dangerous working conditions based on load time series, characterized by: The following steps are involved: S1: For the bearing seat of the wind turbine, calculate the hot spot stress influence matrix under unit load, with loads in positive and negative directions; S2: According to the time series and positive and negative directions of the load, the coefficients in the hot spot stress influence matrix are linearly superimposed to obtain the six stress components of the hot spot; S3: Calculate the hot spot stress at all times and obtain the corresponding time-stress sequence under the load time series; S4: Repeat steps S1 to S3 for each working condition, and convert the time series of loads under all working conditions into a time-stress series; S5: In the time-stress sequence of each working condition, the maximum stress moment is selected, and the load at the maximum stress moment is extracted to perform strength analysis under the corresponding working condition. The strength analysis results are compared to obtain the identification and extraction of the working condition, time, and load at the most dangerous moment.

2. The method for identifying and extracting dangerous working conditions according to claim 1, characterized in that: In step S1, finite element software is used to calculate the hot spot stress influence matrix under unit load.

3. The method for identifying and extracting dangerous working conditions according to claim 1, characterized in that: In step S2, the positive direction coefficient is selected for the load in the positive direction, and the negative direction coefficient is selected for the load in the negative direction, and finally the stress influence matrix at the load moment is obtained.

4. The method for identifying and extracting dangerous working conditions according to claim 1, characterized in that: In step S2, the components of the load are processed by taking absolute values, and then multiplied by the hot spot stress influence matrix at the time corresponding to the load to obtain the six hot spot stress components.

5. The method for identifying and extracting dangerous working conditions according to claim 4, characterized in that: The load components include 6 load components and 1 preload constant term.

6. The method for identifying and extracting dangerous working conditions according to claim 4, characterized in that: In step S3, step S31 is included: According to the six stress components of the hot spot, the Mises theory is used to obtain the hot spot stress σ at that moment.

7. The method for identifying and extracting dangerous working conditions according to claim 6, characterized in that: In step S3, step S32 is included: Repeat steps S1 to S31 to obtain the hot spot stress σ at all times under the working condition and obtain the time-stress sequence.

8. The method for identifying and extracting dangerous working conditions according to claim 1, characterized in that: In step S5, during the strength analysis, the load at the maximum stress moment extracted from each working condition is loaded into the finite element model for strength analysis.

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