Method for determining wind load of mountain cable-supported photovoltaic power station structure and application

Abstract

The invention provides a method, a system and a device for determining a wind load of a mountain cable-supported photovoltaic power station structure, a storage medium and application, and the method comprises the steps: obtaining vibration signal data through a finite vibration sensor, and then carrying out the recognition of a basic frequency parameter and a basic damping parameter of a cable-supported photovoltaic structure; and constructing a wind vibration dynamic model of the cable-supported photovoltaic support structure on the basis of the wind vibration dynamic model, and performing distribution calculation on the wind load of the cable-supported photovoltaic support which obtains the three or more vibration signals on the basis of the constructed wind vibration dynamic model of the cable-supported photovoltaic support structure. According to the method, the full-span wind load distribution of the large-span photovoltaic power station structure can be obtained, the problem of real wind effect evaluation engineering of the flexible photovoltaic support under the complex mountain conditions is solved, key technologies are provided for engineering wind disaster early warning, health evaluation and disaster prevention design, long-term safe operation of the mountain photovoltaic power station is guaranteed, and the method is suitable for popularization and application. And a theoretical foundation can be laid for research and development of a photovoltaic power station full-life-period health monitoring system and equipment under complex terrains.

Description

Technical Field

[0001] The present invention belongs to the field of wind-resistant design and disaster prevention of new energy structures, and in particular relates to a method for determining the wind load of a mountain cable-supported photovoltaic power station structure and its application. Background Art

[0002] In recent years, with the rapid consumption of construction sites such as large roofs and open flat land, the development of photovoltaic power stations has been promoted to complex mountainous areas. In order to improve power generation efficiency and deeply integrate the agricultural photovoltaic complementary industry, a large-span photovoltaic power station structure based on a cable support system has been widely favored by the market in recent years. In a complex mountainous environment, the wind and weather conditions under the interference of local terrain are more complex and changeable, and the large-span cable-supported photovoltaic structure is a wind-sensitive structure, and wind load is the main control load of the design.

[0003] Compared with flat land, the wind effect on photovoltaic structures in mountainous areas is more complicated, and wind-induced vibration and fatigue of photovoltaic structures are frequent. Therefore, effectively evaluating the wind load on the flexible cable-supported photovoltaic power station structure under mountainous conditions is an important basis for carrying out structural wind disaster monitoring and early warning, and guiding wind-resistant and disaster prevention design. However, there is a lack of direct monitoring equipment and means for wind loads. The fundamental reason is that wind loads are not only related to the site wind environment, but also closely related to the aerodynamic shape and structural dynamic characteristics of the structure itself, making it difficult to measure directly.

[0004] Therefore, conducting wind load assessments on photovoltaic power stations in complex mountainous areas also provides key technical support for building a new type of new energy structure health monitoring and early warning system. Summary of the invention

[0005] The first object of the present invention is to provide a method for determining the wind load of a mountain cable-supported photovoltaic power station structure.

[0006] To this end, the above-mentioned purpose of the present invention is achieved by adopting the following technical solutions:

[0007] A method for determining the wind load of a mountain cable-supported photovoltaic power station structure comprises the following steps:

[0008] S1. Vibration signal data acquisition

[0009] Identify the desired vibration signal with a limited vibration sensor;

[0010] The vibration signal is a vibration amplitude response or acceleration response signal of the photovoltaic module; the number of required vibration signals covers photovoltaic modules at least 3 different positions along the span direction of the cable support bracket, and one of the signal sources should be as close as possible to the mid-span position of the structure;

[0011] S2. Identification of dynamic parameters of cable-supported photovoltaic structures

[0012] (1) Identification of basic frequency parameters of cable-supported photovoltaic structures

[0013] According to the structural design model of cable-supported photovoltaics, the geometric dimensions, mass, first three-order resonance frequencies and basic modal information of the structure are determined;

[0014] Considering that the structural resonance frequency may deviate as the engineering service performance weakens and the environment affects it, it is necessary to first update the frequency parameters of the structure; based on the vibration signal obtained in step S1, the following formula (1) is used to change:

[0015] D(ω)=∫U(t)e (-iωt) dt (1)

[0016] In the above formula, D(ω) is the energy spectrum of the displacement signal U(t) in the frequency domain, i is an imaginary number, ω is the circular frequency, e is a natural constant, and t is time;

[0017] After processing by formula (1), the structural wind vibration energy distribution in the frequency domain is obtained, and the first three order resonance frequencies closest to the original design model are found in the resonance peak of the energy spectrum, which are respectively used as the first three order frequencies of the real structure; the first three order frequencies corresponding to the vibration signals at different positions can be obtained respectively, and the first three order frequencies of different signals are averaged to obtain the final first three order resonance frequencies of the structure f1, f2, f3, which are used as the basic frequency parameters for the subsequent construction of the wind vibration force model;

[0018] (2) Identification of damping ratio of cable-supported photovoltaic structures

[0019] The vibration displacement response U(t) of any point on the cable-supported photovoltaic structure can be expressed as follows:

[0020]

[0021] In the above formula, c(t) is the residual, IMF i represents the i-th order eigenmode data sequence, U(t) can be calculated by the following formula:

[0022] s(t)=U(t)-m(t) (3)

[0023] In the above formula, m(t) is the mean of the envelope of the maximum and minimum extreme points of the U(t) curve, and s(t) is the residual after subtracting m(t) from U(t) each time;

[0024] Substitute the obtained s(t) as the new U(t) back into equation (3) and repeat the above iterations until m(t) is 0. At this time, the obtained s(t) is the IMF. Repeat the above operations to obtain the IMFs of various orders. i ;

[0025] Select the IMFs corresponding to the first three structural modal frequenciesi , calculate the free vibration attenuation curve respectively; take ±A as the threshold, the absolute value of A is usually between 0.5σ and 1.5σ, σ is IMF i Standard deviation, to intercept IMF i , a series of intersection points can be obtained, and each intersection point and all subsequent data are extracted as the intercepted signal d(t), forming n intercepted signals d(t) of different lengths, where n is the number of intersection points; the signal intercepted with the -A threshold is given an opposite sign, and all intercepted signals are averaged to obtain the attenuation curve I de (t), as shown in the following formula (4):

[0026]

[0027] The attenuated signal I de (t) is transformed according to formula (5):

[0028]

[0029] Attenuation signal I de The signal amplitude B(t) of (t) is expressed as:

[0030]

[0031] Take the logarithm of the signal amplitude B(t), and use linear fitting to obtain the slope of the equation curve, which is -2πζ i f i , where ζ i is the i-th order damping ratio of the structure, f i The i-th modal frequency of the structure can be obtained by the previous frequency identification;

[0032] From 0.5σ to 1.5σ, the threshold A is taken every 0.05σ, for a total of 21 thresholds. For each value of A, the above formulas (4) to (6) are repeated to obtain the damping ratio under different thresholds and the average is calculated as follows:

[0033]

[0034] In the above formula, ζ i_mean is the i-th order damping ratio of the final structure obtained by the averaging method, ζ ki is the value corresponding to the kth threshold A k The i-th order damping ratio is obtained;

[0035] According to the above formulas (2) to (7), the first three order damping ratios corresponding to the vibration signals at different positions can be obtained respectively. The first three order damping ratios obtained from the signals at different positions are averaged to obtain the final first three order damping ratio of the structure ζ 1_mean , 2_mean , 3_meanAs the basic damping parameter for the subsequent construction of wind vibration force model;

[0036] S3. Construction of wind vibration force model of cable-supported photovoltaic support structure

[0037] The wind vibration force model of the cable-supported photovoltaic support structure is established as shown in the following formula:

[0038] MU+CU+KU=F (8)

[0039] In the above formula, F is the matrix containing the wind load of the photovoltaic modules at different positions in the span direction, U is the matrix containing the displacement of the photovoltaic modules at different positions in the span direction, M is the mass matrix of the photovoltaic modules, C is the damping matrix of the photovoltaic modules, and K is the stiffness matrix of the photovoltaic modules;

[0040] Among them, the mass matrix M is obtained from the structural design model of cable-supported photovoltaics, and the updated stiffness matrix K should satisfy the following formula where Y takes the minimum value:

[0041] Y=[Det(K-2πf1M)] 2 +[Det(K-2πf2M)] 2 +[Det(K-2πf3M)] 2 (9)

[0042] The damping matrix C is calculated using the following formula (10):

[0043] C=αM+βK (10)

[0044] Among them, the parameters α and β are determined according to the following formula:

[0045]

[0046] In the above formula, ω1 and ω2 are the first and second order modal circular frequencies of the cable-supported photovoltaic structure, ξ1 and ξ2 are the first and second order modal damping ratios of the cable-supported photovoltaic structure, respectively;

[0047] S4. Calculation of wind load distribution of cable-supported photovoltaic racks

[0048] (1) Calculation of wind load distribution of cable-supported photovoltaic bracket based on three vibration signals

[0049] According to the vibration displacement signal data U at positions j, k, and m obtained in step S1 j , U k , U m , substituting into the following formula (12), we can obtain the generalized coordinates of the first three modes of the structure, namely q1, q2 and q3:

[0050]

[0051] In the above formula, is the inverse matrix of the first three modal parameters corresponding to the three positions j, k, and m, obtained from the structural design model of cable-supported photovoltaics;

[0052] Substituting the above-obtained generalized coordinates q1, q2 and q3 into the following equation (13), the displacement response of the photovoltaic support structure at different components in the span direction is obtained:

[0053]

[0054] In the above formula, Φ1, Φ2 and Φ3 are the first three modal vectors of the photovoltaic structure respectively;

[0055] Substituting the obtained displacement matrix U into equation (8), the wind load F matrix at different component positions can be obtained;

[0056] (2) Calculation of wind load distribution of cable-supported photovoltaic bracket based on more than three vibration signals

[0057] When the vibration signal contains data from P positions (P>3), any three signals are selected for combination and the above calculation process of wind load distribution of cable-supported photovoltaic bracket based on three vibration signals is repeated to obtain Q groups (Q = P (P-1) (P-2) / 6) of different wind load matrices F1~F Q , the different load results are averaged according to the following formula (14) to obtain the final PV power station wind load distribution result F:

[0058]

[0059] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0060] As a preferred technical solution of the present invention: in step S1, when the vibration signal used is an acceleration response, the acceleration signal should be integrated twice in time to obtain the corresponding displacement signal U(t).

[0061] The second object of the present invention is to provide a system for determining the wind load of a mountain cable-supported photovoltaic power station structure.

[0062] To this end, the above-mentioned purpose of the present invention is achieved by adopting the following technical solutions:

[0063] A system for determining wind loads of a mountain cable-supported photovoltaic power station structure, the system is based on the above-mentioned method for determining wind loads of a mountain cable-supported photovoltaic power station structure, and comprises:

[0064] - a vibration signal data acquisition module, the vibration signal data acquisition module is used to acquire vibration signals of photovoltaic components covering at least three different positions along the span direction of the cable support bracket;

[0065] - a cable-supported photovoltaic structure dynamic parameter identification module, the cable-supported photovoltaic structure dynamic parameter identification module is used to identify the basic frequency parameters and basic damping parameters of the cable-supported photovoltaic structure;

[0066] - A wind vibration force model building module for a cable-supported photovoltaic support structure, wherein the wind vibration force model building module for a cable-supported photovoltaic support structure is used to establish a wind vibration force model for the cable-supported photovoltaic support structure;

[0067] - A cable-supported photovoltaic bracket wind load distribution calculation module, wherein the cable-supported photovoltaic bracket wind load distribution calculation module is used to perform distribution calculation of the cable-supported photovoltaic bracket wind load based on three or more vibration signals.

[0068] The third object of the present invention is to provide a device for determining the wind load of a mountain cable-supported photovoltaic power station structure.

[0069] To this end, the above-mentioned purpose of the present invention is achieved by adopting the following technical solutions:

[0070] A device for determining wind load of a mountain cable-supported photovoltaic power station structure, comprising:

[0071] - at least one processor;

[0072] - at least one memory for storing at least one computer program;

[0073] The processor executes the computer program in the memory to implement the steps of the method for determining the wind load of the mountain cable-supported photovoltaic power station structure as described above.

[0074] A fourth object of the present invention is to provide a computer storage medium.

[0075] To this end, the above-mentioned purpose of the present invention is achieved by adopting the following technical solutions:

[0076] A computer storage medium having a computer program stored thereon, wherein the computer program is executed by a computer to implement the method steps for determining the wind load of a mountain cable-supported photovoltaic power station structure as described above.

[0077] Another object of the present invention is to provide an application of the method for determining the wind load of a mountain cable-supported photovoltaic power station structure described above in wind load assessment, implement the method for determining the wind load of a mountain cable-supported photovoltaic power station structure described above, and obtain the wind load distributed along the span direction of the photovoltaic support structure, and compare it with the test structure under wind tunnel test conditions. When the error between the two is within 15%, the identification result is considered to be more reasonable.

[0078] The present invention provides a method, system, device, storage medium and application for determining the wind load of a cable-supported photovoltaic power station structure in a mountainous area. Vibration signal data is obtained through a limited vibration sensor (e.g., an amplitude displacement sensor), and then the basic frequency parameters and basic damping parameters of the cable-supported photovoltaic structure are identified, and a wind vibration force model of the cable-supported photovoltaic support structure is constructed based on this. Based on the constructed wind vibration force model of the cable-supported photovoltaic support structure, the wind load of the cable-supported photovoltaic support that obtains 3 or more vibration signals is distributed and calculated. The present invention can obtain the wind load distribution of the entire span of a large-span photovoltaic power station structure, solve the engineering problem of evaluating the real wind effect of flexible photovoltaic supports under complex mountainous conditions, provide key technologies for engineering wind disaster warning, health assessment and disaster prevention design, ensure the long-term safe operation of mountain photovoltaic power stations, and lay a theoretical foundation for the development of health monitoring systems and equipment for photovoltaic power stations throughout their life cycle under complex terrain. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 This is a schematic diagram of the cable-supported photovoltaic support structure;

[0080] Figure 2 It is the wind load time history diagram of each component of the cable-supported photovoltaic bracket; DETAILED DESCRIPTION

[0081] A method for determining the wind load of a mountain cable-supported photovoltaic power station structure comprises the following steps:

[0082] 1) Vibration signal data acquisition

[0083] The vibration signal required for identification by this method can be the vibration amplitude response or acceleration response signal of the photovoltaic module. The number of required vibration signals covers at least three photovoltaic modules at different positions along the span direction of the cable support bracket, and one of the signal sources should be as close as possible to the mid-span position of the structure. When the vibration signal used is an acceleration response, the acceleration signal should be integrated twice in time to obtain the corresponding displacement signal U(t).

[0084] 2) Identification of dynamic parameters of cable-supported photovoltaic structures and construction of wind vibration force model

[0085] 2.1) According to the cable-supported photovoltaic structure design model, determine the basic information of the structure, such as geometric dimensions, mass, first three-order resonance frequencies and modes. Considering that the structural resonance frequency may deviate with the weakening of engineering service performance and the influence of the environment, it is necessary to update the frequency parameters of the structure first. According to the vibration signal obtained in step 1, change it according to the following formula (1):

[0086] D(ω)=∫U(t)e (-iωt) dt (1)

[0087] In the above formula, D(ω) is the energy spectrum of the displacement signal U(t) in the frequency domain, i is an imaginary number, ω is the circular frequency, e is a natural constant, and t is time;

[0088] After processing by formula (1), the structural wind vibration energy distribution in the frequency domain is obtained, and the first three order resonance frequencies closest to the original design model are found in the resonance peak of the energy spectrum, which are used as the first three order frequencies of the real structure. The first three order frequencies corresponding to the vibration signals at different positions can be obtained respectively, and the first three order frequencies of different signals are averaged to obtain the final first three order resonance frequencies of the structure f1, f2, and f3, which are used as the basic frequency parameters for the subsequent construction of the wind vibration force model.

[0089] 2.2) Identification of structural damping ratio

[0090] The vibration displacement response U(t) of any point on the cable-supported photovoltaic structure can be expressed as follows:

[0091]

[0092] In the above formula, c(t) is the residual, IMF i represents the i-th order eigenmode data sequence, U(t) can be calculated by the following formula:

[0093] s(t)=U(t)-m(t) (3)

[0094] In the above formula, m(t) is the mean of the envelope of the maximum and minimum extreme points of the U(t) curve, and s(t) is the residual after subtracting m(t) from U(t) each time;

[0095] Substitute the obtained s(t) as the new U(t) back into equation (3) and repeat the above operation until m(t) is 0. At this time, the obtained s(t) is the IMF. Repeat the above operation to obtain the IMF of each order i .

[0096] Select the IMFs corresponding to the first three structural modal frequencies i , calculate their free vibration attenuation curves respectively. Take ±A as the threshold (the absolute value of A is usually between 0.5σ and 1.5σ, σ is the IMF i standard deviation), to intercept the IMF i , a series of intersections can be obtained, and each intersection and all subsequent data are extracted as the intercepted signal d(t), forming n (n is the number of intersections) intercepted signals d(t) of different lengths. The signal intercepted with the -A threshold is given an opposite sign, and all intercepted signals are averaged to obtain the attenuation curve I de (t), as shown in the following formula (4):

[0097]

[0098] The attenuated signal I de (t) is transformed according to formula (5):

[0099]

[0100] The signal amplitude can be expressed as:

[0101]

[0102] Take the logarithm of the signal amplitude B(t), and use linear fitting to obtain the slope of the equation curve, which is -2πζ i f i , where ζ i is the i-th order damping ratio of the structure, f i The i-th modal frequency of the structure can be obtained by the previous frequency identification.

[0103] In the calculation, the threshold A can be taken from 0.5σ to 1.5σ every 0.05σ, for a total of 21 thresholds. For each value of A, repeat the above formulas (4) to (6) to obtain the damping ratio under different thresholds and take the average according to the following formula:

[0104]

[0105] In the above formula, ζ i_mean is the i-th order damping ratio of the final structure obtained by the averaging method, ζ ki is the value corresponding to the kth threshold A k The i-th order damping ratio is obtained.

[0106] According to the above formulas (2) to (7), the first three order damping ratios corresponding to the vibration signals at different positions can be obtained respectively. The first three order damping ratios obtained from the signals at different positions are averaged to obtain the final first three order damping ratio of the structure ζ 1_mean , 2_mean , 3_mean It serves as the basic damping parameter for the subsequent construction of wind vibration force model.

[0107] 2.3) Establish the wind vibration force model of the cable-supported photovoltaic support structure.

[0108] MU+CU+KU=F (8)

[0109] In the above formula, F is the matrix containing the wind load of the photovoltaic modules at different positions in the span direction, U is the matrix containing the displacement of the photovoltaic modules at different positions in the span direction, M is the mass matrix of the photovoltaic modules, C is the damping matrix of the photovoltaic modules, and K is the stiffness matrix of the photovoltaic modules;

[0110] Among them, the mass matrix M can be obtained from the structural design model, and the updated stiffness matrix K should satisfy the following formula Y to obtain the minimum value,

[0111] Y=[Det(K-2πf1M)] 2 +[Det(K-2πf2M)] 2 +[Det(K-2πf3M)] 2 (9)

[0112] The damping matrix C is calculated using the following formula (10):

[0113] C=αM+βK (10)

[0114] The parameters α and β are determined according to the following formula.

[0115]

[0116] In the above formula, ω1 and ω2 are the first and second order modal circular frequencies of the cable-supported photovoltaic structure, ξ1 and ξ2 are the first and second order modal damping ratios of the cable-supported photovoltaic structure, respectively;

[0117] 3) Calculation of wind load distribution of cable-supported photovoltaic bracket based on three vibration signals

[0118] According to the vibration displacement signal data U at positions j, k, and m obtained in step 1 j , U k , U m , substituting into the following formula (12), we can obtain the generalized coordinates of the first three modes of the structure, namely q1, q2 and q3.

[0119]

[0120] In the above formula, is the inverse matrix of the first three modal parameters corresponding to the three positions j, k, and m, which is obtained from the structural design model of cable-supported photovoltaics.

[0121] Substituting the above-obtained generalized coordinates q1, q2 and q3 into the following formula (13), the displacement response of the photovoltaic support structure at components at different positions in the span direction can be obtained.

[0122]

[0123] In the above formula, Φ1, Φ2 and Φ3 are the first three modal vectors of the photovoltaic structure respectively;

[0124] Substituting the obtained displacement matrix U into equation (8), the wind load matrix F at different component positions can be obtained.

[0125] 4) Calculation of wind load distribution of cable-supported photovoltaic racks based on more than three vibration signals

[0126] When the vibration signal contains data from P locations (P>3), select any three signals to combine and repeat the process of step 3, so that Q groups (Q = P (P-1) (P-2) / 6) of different wind load matrices can be obtained, that is, F1~F Q , the different load results are averaged according to the following formula (14) to obtain the final PV power station wind load distribution result F:

[0127]

[0128] The present invention also provides a system for determining the wind load of a mountain cable-supported photovoltaic power station structure. The system is based on the method for determining the wind load of a mountain cable-supported photovoltaic power station structure described above, and comprises:

[0129] - a vibration signal data acquisition module, the vibration signal data acquisition module is used to acquire vibration signals of photovoltaic components covering at least three different positions along the span direction of the cable support bracket;

[0130] - a cable-supported photovoltaic structure dynamic parameter identification module, the cable-supported photovoltaic structure dynamic parameter identification module is used to identify the basic frequency parameters and basic damping parameters of the cable-supported photovoltaic structure;

[0131] - A wind vibration force model building module for a cable-supported photovoltaic support structure, wherein the wind vibration force model building module for a cable-supported photovoltaic support structure is used to establish a wind vibration force model for the cable-supported photovoltaic support structure;

[0132] - A cable-supported photovoltaic bracket wind load distribution calculation module, wherein the cable-supported photovoltaic bracket wind load distribution calculation module is used to perform distribution calculation of the cable-supported photovoltaic bracket wind load based on three or more vibration signals.

[0133] The present invention also provides a device for determining the wind load of a mountain cable-supported photovoltaic power station structure, comprising:

[0134] - at least one processor;

[0135] - at least one memory for storing at least one computer program;

[0136] The processor executes the computer program in the memory to implement the steps of the method for determining the wind load of the mountain cable-supported photovoltaic power station structure as described above.

[0137] The present invention also provides a computer storage medium having a computer program stored thereon, and the computer program is executed by a computer to implement the method steps for determining the wind load of the mountain cable-supported photovoltaic power station structure as described above.

[0138] The present invention also provides the application of the method for determining the wind load of the mountain cable-supported photovoltaic power station structure mentioned above in wind load assessment. The method for determining the wind load of the mountain cable-supported photovoltaic power station structure is implemented and the wind load distributed along the span direction of the photovoltaic support structure is obtained, and the wind load is compared with the test structure under wind tunnel test conditions. When the error between the two is within 15%, the identification result is considered to be relatively reasonable.

[0139] Specifically, the present invention is further described by the following examples.

[0140] The flexible cable supported photovoltaic power station is located in a coastal mountainous terrain. The structure has a span of about 15m. It is composed of two cables and beams and columns to form the basic supporting structure. Seven photovoltaic modules are arranged along the cable span direction, and the module inclination angle is 0°. Three acceleration sensors C2, C4 and C6 are arranged in the middle of the structure and the second module position on both sides. The structural model is as follows: Figure 1 As shown in the figure, the collected acceleration signals are a2, a4 and a6 respectively.

[0141] 1) Acceleration signals a2, a4 and a6 are quadratically integrated over time to obtain displacement response data U2, U4 and U6.

[0142] 2) Substituting U2, U4 and U6 into formula (1) respectively, we can get the corresponding three groups of first three order frequencies (f 21 , f 22 and f 23 )、(f 41 , f 42 and f 43 )、(f 61 , f 62 and f 63 ), and the first three frequencies of the photovoltaic support structure are obtained by averaging the three sets of frequency data. f1 = 4.4 Hz, f2 = 8.7 Hz and f3 = 9.8 Hz). Substituting U2, U4 and U6 into formulas (2) to (7), the first three damping ratios (ξ 21 ,ξ 22 and 23 )、(ξ 41 ,ξ 42 and 43 )、(ξ 61 ,ξ 62 and 63 ), the three groups of damping ratio data are averaged to obtain the first three damping ratios of the photovoltaic support structure: ξ1 = 1.05%, ξ2 = 1.28% and ξ3 = 1.83%). According to the obtained structural frequency, damping ratio and design model mass matrix, they are substituted into formulas (8) to (11) to obtain the wind vibration force model of the structure.

[0143] 3) Substitute U2, U4 and U6 into formulas (12) to (13) to obtain the displacement response U at different positions in the span direction of the photovoltaic support structure. Substitute the displacement response U into formula (8) to obtain the wind load F1 to F7 distributed along the span, as follows: Figure 2 shown.

[0144] The wind tunnel test was used to simulate the wind pressure under similar environmental conditions on the cable-supported photovoltaic bracket model. The maximum error between the average wind pressure test results of each component and the results identified by the present invention was 9.8%, which can meet the needs of engineering applications.

[0145] The above-mentioned specific implementation methods are used to explain the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for determining wind loads on a mountain cable-supported photovoltaic power station structure, characterized in that: The method comprises the following steps: S1. Vibration signal data acquisition Identify the desired vibration signal with a limited vibration sensor; The vibration signal is a vibration amplitude response or acceleration response signal of the photovoltaic module; the number of required vibration signals covers photovoltaic modules at least 3 different positions along the span direction of the cable support bracket, and one of the signal sources should be as close as possible to the mid-span position of the structure; S2. Identification of dynamic parameters of cable-supported photovoltaic structures (1) Identification of basic frequency parameters of cable-supported photovoltaic structures According to the structural design model of cable-supported photovoltaics, the geometric dimensions, mass, first three-order resonance frequencies and basic modal information of the structure are determined; Considering that the structural resonance frequency may deviate as the engineering service performance weakens and the environment affects it, it is necessary to first update the frequency parameters of the structure; based on the vibration signal obtained in step S1, the following formula (1) is used to change: D(ω)=∫U(t)e (-iωt) dt (1) In the above formula, D(ω) is the energy spectrum of the displacement signal U(t) in the frequency domain, i is an imaginary number, ω is the circular frequency, e is a natural constant, and t is time; After processing by formula (1), the structural wind vibration energy distribution in the frequency domain is obtained, and the first three order resonance frequencies closest to the original design model are found in the resonance peak of the energy spectrum, which are respectively used as the first three order frequencies of the real structure; the first three order frequencies corresponding to the vibration signals at different positions can be obtained respectively, and the first three order frequencies of different signals are averaged to obtain the final first three order resonance frequencies of the structure f1, f2, f3, which are used as the basic frequency parameters for the subsequent construction of the wind vibration force model; (2) Identification of damping ratio of cable-supported photovoltaic structures The vibration displacement response U(t) of any point on the cable-supported photovoltaic structure can be expressed as follows: In the above formula, c(t) is the residual, IMF i represents the i-th order eigenmode data sequence, U(t) can be calculated by the following formula: s(t)=U(t)-m(t) (3) In the above formula, m(t) is the mean of the envelope of the maximum and minimum extreme points of the U(t) curve, and s(t) is the residual after subtracting m(t) from U(t) each time; Substitute the obtained s(t) as the new U(t) back into equation (3) and repeat the above iterations until m(t) is 0. At this time, the obtained s(t) is the IMF. Repeat the above operations to obtain the IMFs of various orders. i ; Select the IMFs corresponding to the first three structural modal frequencies i , calculate the free vibration attenuation curve respectively; take ±A as the threshold, the absolute value of A is usually between 0.5σ and 1.5σ, σ is IMF i Standard deviation, to intercept IMF i , a series of intersection points can be obtained, and each intersection point and all subsequent data are extracted as the intercepted signal d(t), forming n intercepted signals d(t) of different lengths, where n is the number of intersection points; Take the opposite sign of the signal intercepted by the -A threshold, and average all the intercepted signals to obtain the attenuation curve I de (t), as shown in the following formula (4): The attenuated signal I de (t) is transformed according to formula (5): Attenuation signal I de The signal amplitude B(t) of (t) is expressed as: Take the logarithm of the signal amplitude B(t), and use linear fitting to obtain the slope of the equation curve, which is -2πζ i f i , where ζ i is the i-th order damping ratio of the structure, f i The i-th modal frequency of the structure can be obtained from the previous frequency identification; From 0.5σ to 1.5σ, the threshold A is taken every 0.05σ, for a total of 21 thresholds. For each value of A, the above formulas (4) to (6) are repeated to obtain the damping ratio under different thresholds and the average is calculated as follows: In the above formula, ζ i_mean is the i-th order damping ratio of the final structure obtained by the averaging method, ζ ki is the value corresponding to the kth threshold A k The i-th order damping ratio is obtained; According to the above formulas (2) to (7), the first three order damping ratios corresponding to the vibration signals at different positions can be obtained respectively. The first three order damping ratios obtained from the signals at different positions are averaged to obtain the final first three order damping ratio of the structure ζ 1_mean , 2_mean , 3_mean As the basic damping parameter for the subsequent construction of wind vibration force model; S3. Construction of wind vibration force model of cable-supported photovoltaic support structure The wind vibration force model of the cable-supported photovoltaic support structure is established as shown in the following formula: MU+CU+KU=F (8) In the above formula, F is the matrix containing the wind load of the photovoltaic modules at different positions in the span direction, U is the matrix containing the displacement of the photovoltaic modules at different positions in the span direction, M is the mass matrix of the photovoltaic modules, C is the damping matrix of the photovoltaic modules, and K is the stiffness matrix of the photovoltaic modules; Among them, the mass matrix M is obtained from the structural design model of cable-supported photovoltaics, and the updated stiffness matrix K should satisfy the following formula where Y takes the minimum value: Y=[Det(K-2πf1M)] 2 +[Det(K-2πf2M)] 2 +[Det(K-2πf3M)] 2 (9) The damping matrix C is calculated using the following formula (10): C=αM+βK (10) Among them, the parameters α and β are determined according to the following formula: In the above formula, ω1 and ω2 are the first and second order modal circular frequencies of the cable-supported photovoltaic structure, ξ1 and ξ2 are the first and second order modal damping ratios of the cable-supported photovoltaic structure, respectively; S4. Calculation of wind load distribution of cable-supported photovoltaic racks (1) Calculation of wind load distribution of cable-supported photovoltaic bracket based on three vibration signals According to the vibration displacement signal data U at positions j, k, and m obtained in step S1 j , U k , U m , substituting into the following formula (12), we can obtain the generalized coordinates of the first three modes of the structure, namely q1, q2 and q3: In the above formula, is the inverse matrix of the first three modal parameters corresponding to the three positions j, k, and m, obtained from the structural design model of cable-supported photovoltaics; Substituting the above-obtained generalized coordinates q1, q2 and q3 into the following equation (13), the displacement response of the photovoltaic support structure at different components in the span direction is obtained: In the above formula, Φ1, Φ2 and Φ3 are the first three modal vectors of the photovoltaic structure respectively; Substituting the obtained displacement matrix U into equation (8), the wind load F matrix at different component positions can be obtained; (2) Calculation of wind load distribution of cable-supported photovoltaic bracket based on more than three vibration signals When the vibration signal contains data from P positions (P>3), any three signals are selected for combination and the above calculation process of wind load distribution of cable-supported photovoltaic bracket based on three vibration signals is repeated to obtain Q groups (Q = P (P-1) (P-2) / 6) of different wind load matrices F1~F Q , the different load results are averaged according to the following formula (14) to obtain the final PV power station wind load distribution result F:

2. The method for determining the wind load of a mountain cable-supported photovoltaic power station structure according to claim 1 is characterized in that: In step S1, when the vibration signal used is an acceleration response, the acceleration signal should be integrated twice in time to obtain the corresponding displacement signal U(t).

3. A system for determining wind loads on mountain cable-supported photovoltaic power station structures, characterized in that: The system is based on the method for determining the wind load of the mountain cable-supported photovoltaic power station structure according to claim 1, and includes: - a vibration signal data acquisition module, the vibration signal data acquisition module is used to acquire vibration signals of photovoltaic components covering at least three different positions along the span direction of the cable support bracket; - a cable-supported photovoltaic structure dynamic parameter identification module, the cable-supported photovoltaic structure dynamic parameter identification module is used to identify the basic frequency parameters and basic damping parameters of the cable-supported photovoltaic structure; - A wind vibration force model building module for a cable-supported photovoltaic support structure, wherein the wind vibration force model building module for a cable-supported photovoltaic support structure is used to establish a wind vibration force model for the cable-supported photovoltaic support structure; - A cable-supported photovoltaic bracket wind load distribution calculation module, wherein the cable-supported photovoltaic bracket wind load distribution calculation module is used to perform distribution calculation of the cable-supported photovoltaic bracket wind load based on three or more vibration signals.

4. A device for determining wind loads on a mountain cable-supported photovoltaic power station structure, characterized in that: The device comprises: - at least one processor; - at least one memory for storing at least one computer program; The processor executes the computer program in the memory to implement the steps of the method for determining the wind load of the mountain cable-supported photovoltaic power station structure as claimed in claim 1.

5. A computer storage medium, characterized in that: The computer storage medium stores a computer program, which is executed by a computer to implement the steps of the method for determining the wind load of a mountain cable-supported photovoltaic power station structure as described in claim 1.

6. Application of the method for determining wind load of a mountain cable-supported photovoltaic power station structure according to claim 1 in wind load assessment.

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