Method for analyzing influence of echo characteristics of draught fan of proposed offshore wind plant on radar

Abstract

The invention belongs to the technical field of radar signal reflection, and provides a method for analyzing the influence of echo characteristics of a fan of a proposed offshore wind plant on radar. The analysis method comprises the following steps: S1, establishing an overall model of a single fan; s2, radar echoes are calculated according to the overall model, specifically, S2.1, the radar echoes of the fan blades are calculated; s2.2, radar echoes of the fan tower are calculated; s2.3, adding the radar echo of the blade and the radar echo of the tower to obtain the radar echo of the overall model; and S3, analyzing the RCS echo influence of the proposed offshore wind turbines at different positions on the radar. According to the analysis method, radar detection correction or construction scheme correction of the proposed offshore wind farm is guided before the offshore wind farm is constructed according to the analysis result of the influence of the proposed offshore wind turbines at different positions on the RCS echoes of the radar, and the influence of the echo characteristics of the established offshore wind farm on the detection performance of the active radar is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of radar signal reflection, and in particular to a method for analyzing the influence of the echo characteristics of wind turbines in a planned offshore wind farm on radar. Background Art

[0002] Wind energy is a clean, renewable energy source with abundant reserves. The development of new energy is an important part of China's energy development strategy. The Renewable Energy Law of the People's Republic of China explicitly encourages the development of new energy power generation and energy-saving projects. As the scale and number of wind farm construction projects increase, the impact of wind farms on the environment will gradually become apparent, especially in terms of the impact on radar performance. It will impose certain restrictions on the early warning detection capabilities of radars, resulting in a reduction in radar performance. This mainly refers to the false target impact caused by the reflection of wind turbines on radar signals.

[0003] Due to the large size of wind turbines, the radar beam will form a strong echo signal, which can cause the radar to detect the echo signal and form a false alarm. In addition, due to the wide distribution area of ​​wind farms, large bright spots may be formed on the radar display, making it impossible for the radar to correctly identify the target. Even strong reflection echoes from wind farms very close to the radar may cause saturation of the radar receiver's RF front end and damage the radar equipment. Due to the increasing size and power of the planned offshore wind turbines and the increasing complexity of the materials, the RCS (radar cross section) of the wind turbines is very large, comparable to the RCS of Boeing 747 aircraft, which will cause the radar receiver to saturate or mask the target echo signal.

[0004] According to the current situation, we can observe the influence of wind turbine RCS of the built offshore wind farm on the radar detection performance from the radar interface. Since the offshore wind farm we calculated and analyzed is in the demonstration stage and has not yet been built, it is difficult to directly observe the influence of offshore wind turbine RCS echo from the radar interface display. Therefore, it is necessary to conceive a method to analyze the influence of wind turbine echo characteristics of the proposed offshore wind farm on the active radar detection performance. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a method for analyzing the impact of the echo characteristics of wind turbines in a planned offshore wind farm on radar, so as to solve or partially solve the above problems.

[0006] In a first aspect, an embodiment of the present invention provides a method for analyzing the impact of wind turbine echo characteristics of a proposed offshore wind farm on radar, comprising the following steps:

[0007] S1: Establish the overall model of a single wind turbine;

[0008] S2: Calculate the radar echo according to the overall model, specifically:

[0009] S2.1: Calculate the radar echo of the wind turbine blades;

[0010] S2.2: Calculate the radar echo of the wind turbine tower;

[0011] S2.3: adding the radar echo of the blade and the radar echo of the tower to obtain the radar echo of the overall model;

[0012] S3: Analyze the impact of proposed offshore wind turbines at different locations on the radar RCS echo.

[0013] The beneficial effects of the above embodiment are as follows:

[0014] Based on the analysis results of the impact of the proposed offshore wind turbines at different locations on the RCS echo of the radar in step 3, this analysis method modifies the construction plan of the proposed offshore wind farm before the construction of the offshore wind farm to avoid the impact of the echo characteristics of the established offshore wind farm on the active radar detection performance.

[0015] According to a specific implementation manner of an embodiment of the present invention, the analysis method uses electromagnetic simulation software FEKO to perform simulation analysis.

[0016] According to a specific implementation of the embodiment of the present invention, the overall model of the wind turbine includes the blades and the tower.

[0017] According to a specific implementation of an embodiment of the present invention, in step S2, a three-dimensional coordinate system is established with the center point of the blade as the origin O of the coordinate system and the direction perpendicular to the rotation plane of the blade as the x-axis; then the radar echo of the equivalent scattering point on the overall model of the wind turbine is:

[0018]

[0019] In the formula, f c and λ represent the center frequency of the radar transmitting signal and the operating wavelength of the radar respectively, and R is the distance from the equivalent scattering point to the radar.

[0020] According to a specific implementation of an embodiment of the present invention, the equivalent scattering point is obtained as follows: the wind turbine is triangulated by using a triangular facet subdivision method, and the center of the triangular facet is taken as the equivalent scattering point.

[0021] According to a specific implementation of an embodiment of the present invention, the distance R from the equivalent scattering point to the radar is calculated as follows:

[0022]

[0023] In formula (2), X B , Y B , ZB represents the coordinate scale of the radar in the three-dimensional coordinate system; X Pi , Y Pi , Z Pi Represents the coordinate scale of the equivalent scattering point Pi in the three-dimensional coordinate system.

[0024] According to a specific implementation of the embodiment of the present invention, in step S2.1, the echo signal of the entire blade is expressed as:

[0025]

[0026] Where L is the length of the blade; f c and λ represent the center frequency of the radar transmission signal and the working wavelength of the radar respectively; L OB represents the distance between the radar and the coordinate origin; δ represents the distance between the blade and the radar line of sight L OS The angle between the two angles is , where cosδ is calculated as:

[0027] cosδ=cosθ k t sinαsinβ+sinθ k t cosβ;

[0028] α represents the angle between the projection of the radar line of sight LOS in the XOY plane and the X-axis, β represents the angle between the radar line of sight LOS and the positive direction of the Z-axis; θ k t It represents the angle between the blade and the positive direction of the Y axis, and is calculated as follows:

[0029]

[0030] Wherein ω represents the angular velocity of the blade rotation.

[0031] According to a specific implementation of the embodiment of the present invention, in step S2.1, it is also necessary to obtain a radar echo sequence under the blade rotation period.

[0032] According to a specific implementation of an embodiment of the present invention, in step S2.2, the tower echo calculation method is as follows:

[0033] The tower scattering cross section is assumed to be in the same plane as the blade, and the radar coordinate is B(X B , Y B , Z B ) The radar coordinates after transformation are B'(X B' , Y B' , Z B' ):

[0034]

[0035] in, represents the distance from the radar to the origin of the coordinate system; γ represents the angle between the line connecting the radar and the origin of the coordinate system and the XOY plane;

[0036] The equivalent distance between the scattering point on the tower and the radar is expressed as:

[0037]

[0038] The radar echo of the tower is the same at every moment, expressed as:

[0039]

[0040] The radar echo of the tower is expressed as:

[0041]

[0042] Wherein, H represents the height of the tower.

[0043] In a second aspect, an embodiment of the present invention provides a device for analyzing the influence of the echo characteristics of wind turbines in a proposed offshore wind farm on radar, comprising:

[0044] Establish modules to build the overall model of a single wind turbine;

[0045] A calculation module, used to calculate the radar echo according to the overall model, specifically: calculate the radar echo of the wind turbine blade; calculate the radar echo of the wind turbine tower; add the radar echo of the blade and the radar echo of the tower to obtain the radar echo of the overall model;

[0046] The analysis module is used to analyze the impact of proposed offshore wind turbines at different locations on the radar's RCS echo. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0048] Figure 1 A flowchart showing the steps of a method for analyzing the impact of wind turbine echo characteristics of a proposed offshore wind farm on radar provided by an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of a three-dimensional coordinate system in an embodiment of the present invention is shown;

[0050] Figure 3 A schematic diagram of selecting scattering points of fan blades in an embodiment of the present invention is shown;

[0051] Figure 4 A flow chart of fan blade echo simulation calculation in an embodiment of the present invention is shown;

[0052] Figure 5 The simulation of the radar beam irradiating the wind turbine with the azimuth angle in the embodiment of the present invention is shown. Figure 1 ;

[0053] Figure 6 The simulation of the radar beam irradiating the wind turbine with the pitch angle in the embodiment of the present invention is shown. Figure 1 ;

[0054] Figure 7 The simulation of the radar beam irradiating the wind turbine with the azimuth angle in the embodiment of the present invention is shown. Figure 2 ;

[0055] Figure 8 The simulation of the radar beam irradiating the wind turbine with the pitch angle in the embodiment of the present invention is shown. Figure 2 ;

[0056] Fig. 9 The simulation of the radar beam irradiating the wind turbine with the azimuth angle in the embodiment of the present invention is shown. Figure 3 ;

[0057] Fig.10 The simulation of the radar beam irradiating the wind turbine with the pitch angle changes in the embodiment of the present invention is shown. Figure 3 ;

[0058] Fig.11 A structural block diagram of a device for analyzing the influence of wind turbine echo characteristics of a proposed offshore wind farm on radar provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0059] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0060] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0061] This application uses FEKO software for simulation analysis. FEKO software has outstanding advantages in the field of electromagnetic simulation analysis, especially in the analysis of electrically large-size problems, and has become a leading product in the field of electromagnetic simulation. Applications involve radar systems, antennas, antenna layouts, electromagnetic compatibility, waveguides, radomes, microstrip circuits, bio-electromagnetism and other fields. It has technical features such as electrically large-size electromagnetic problems, multi-layer fast multipoles, single-station RCS fast convergence technology, and wind window antenna simulation technology. FEKO mainly integrates full-wave frequency domain algorithms: MOM, FEM, MLFMM; full-wave time domain method: FDTD; high-frequency approximation methods: PO, LE-PO, RL-GO, UTD. Reasonable selection of the electromagnetic calculation method to be used according to the electrical size of the target and the complexity of the material will improve the accuracy of the results and save computing resources and time. There are three major modules in FEKO: CADFEKO, EDITFEKO, and POSTFEKO. CADFEKO is mainly used to create target 3D models, set electromagnetic wave frequency, incident electromagnetic wave direction, scattered electromagnetic wave direction, electromagnetic calculation algorithm, model segmentation, etc. EDITFEKO is used to perform advanced settings on the model created in CADFEKO through scripting language. POSTFEKO is mainly used for displaying, processing and exporting calculation results.

[0062] Figure 1 A flowchart of the steps of a method for analyzing the impact of wind turbine echo characteristics on radar in a proposed offshore wind farm provided by an embodiment of the present invention, see Figure 1 , the method comprises the following steps:

[0063] S1: Establish the overall geometric model of the wind turbine, including blades and tower;

[0064] The hub is included in the blade modeling.

[0065] S2: Calculate radar echoes based on the overall geometric model.

[0066] The fan blades and tower are equivalent to slender cylinders, and the cylinders are divided into a series of thin discs along the axial direction. The fan echo can be approximated as the synthesis of the echoes from the center points of a series of thin discs.

[0067] Under the influence of a single wind turbine, the relationship between the radar and the wind turbine blade position is as follows: Figure 2 Take the static posture of the fan at any fixed moment to carry out the geometric modeling of the fan, and take the center point of the fan blade as the origin O of the coordinate system, and the direction perpendicular to the blade rotation plane as the x-axis, and establish the following Figure 2 The three-dimensional coordinate system shown.

[0068] Based on the radar echo from any target point:

[0069]

[0070] In formula (1), f c and λ respectively represent the center frequency of the radar transmission signal and the working wavelength of the radar. It can be seen that the decisive parameter affecting the radar echo is R, that is, the distance from the equivalent scattering point of the wind turbine to the radar. In order to obtain the equivalent scattering point considering the wind turbine shape model, the triangular facet subdivision method is used in the analysis process of this embodiment to triangulate the wind turbine and take the center of the triangular facet as the equivalent scattering point.

[0071] Considering the fineness of the division and the amount of simulation calculation, λ / 10 is finally selected as the division size, as shown in Figure 3 The coordinates of the center points of each grid are determined by the initial posture of the wind turbine, and the radar echo of each scattering point can be calculated by substituting all the center points of the grid into the formula.

[0072] Considering that the key parameter R in the fan shape model is determined by the distance formula between two points, then:

[0073]

[0074] In formula (2), X B , Y B , Z B Indicates the coordinate scale of the radar in the three-dimensional coordinate system; X Pi , Y Pi , Z Pi Represents the coordinate scale of the scattering point in the three-dimensional coordinate system.

[0075] S2.1: Echo calculation of fan blades;

[0076] Since the fan blades are rotating, the postures of the blades are different at different times, and the coordinate positions of the scattering points of the blades are also changing. Assume that a scattering point (0, Y0, Z0) on the fan rotates with the blade for Δt time, and its coordinates are (0, Y t , Z t ), it is not difficult to get:

[0077]

[0078] In formula (3), Indicates the distance from the known point to the origin of the coordinate system; ω indicates the angular velocity of the fan blades, in revolutions per second. ψ indicates the angle between the scattering point (0, Y0, Z0) and the origin and the Y axis, where when Z0>0, ψ=arccosY0 / l0; when Z0≤0, ψ=arccos Y0 / l0+π.

[0079] Substituting equation (3) into equation (2) yields the distance between the wind turbine equivalent scattering point and the radar, and substituting it into the radar echo expression yields the radar echo data of each scattering point at that moment. Adding the echo data obtained from all scattering points yields the wind turbine radar echo at that moment, which can be expressed by equation (4).

[0080]

[0081] In formula (4), M represents the number of blade scattering points. Since the blade is rotating, the angle between the fan blade and the positive direction of the Y axis at any time can be expressed as:

[0082]

[0083] In formula (5) represents the angle between the kth blade and the positive direction of the Y axis at time t; ω represents the angular velocity of the blade rotation. The echo signal of the entire blade can be expressed as:

[0084]

[0085] In formula (6), L represents the length of the blade; fc and λ represent the center frequency of the radar transmission signal and the working wavelength of the radar respectively; L OB represents the distance from the radar to the origin of the coordinate system; δ represents the angle between the blade and the radar line of sight LOS. Among them, cosδ is:

[0086] cosδ=cosθ k t sinαsinβ+sinθ k t cosβ (7);

[0087] θ k t It represents the angle between the blade and the positive direction of the Y axis, α represents the angle between the projection of the radar line of sight LOS in the XOY plane and the X axis, and β represents the angle between the radar LOS and the positive direction of the Z axis.

[0088] Acquire the radar echo sequence under the rotation period of the wind turbine blades.

[0089] In order to obtain the fan shape model, the electromagnetic scattering sequence within one rotation cycle of the blades is solved, and the calculation is still performed in the form of snapshots of the fan at discrete moments. The geometric position information of the moving fan blades at each discrete moment in the rotation cycle is converted into a three-dimensional coordinate system, and then the distance from the scattering point to the radar at different moments is calculated to obtain the radar echo sequence. The specific process is as follows Figure 4 shown.

[0090] S2.2: Echo calculation of wind turbine tower;

[0091] Since the tower is stationary, the tower radar echo is only related to the number and position of the scattering points of the hub-tower. Considering the truncated cone shape of the tower, no matter where the radar is located, the tower can always present a trapezoidal cross-section to provide a scattering area. In order to simplify the calculation, when solving the tower radar echo, the radar coordinates need to be converted to the front position of the wind turbine. The scattering cross section of the wind turbine tower is assumed to be on the same plane as the wind turbine blades, and the radar coordinates are B(X B , Y B , Z B )The transformed radar coordinates are B'(X B' , Y B' , Z B' ):

[0092]

[0093] in, represents the distance from the radar to the origin of the coordinate system; γ represents the angle between the line connecting the radar and the origin of the coordinate system and the XOY plane. The equivalent distance between the scattering point on the wind turbine tower and the radar is expressed by formula (9):

[0094]

[0095] The radar echo of the wind turbine tower is the same at every moment and can be expressed by equation (10):

[0096]

[0097] The radar echo of the wind turbine tower can be expressed as:

[0098]

[0099] In formula (11), H represents the height of the wind turbine tower, and the meanings of other variables are the same as in the previous formula.

[0100] S2.3: Finally, the blade radar echo and tower radar echo obtained in steps 2.1 and 2.2 are added together to obtain the overall radar echo of a single wind turbine under the model.

[0101] S3: Analyze the impact of proposed offshore wind turbines at different locations on the radar RCS echo.

[0102] According to the analysis results of the impact of the planned offshore wind turbines in different locations on the radar's RCS echo, guidance is provided for the correction of radar detection or the correction of the construction plan of the offshore wind farm.

[0103] The following is a specific implementation case:

[0104] Taking a wind farm to be built in a certain sea area in the east as an example, the wind turbine parameters to be selected are as follows: the installed capacity of a single wind turbine is 14MW, mainly composed of blades, hubs and towers, of which the hubs and towers are mainly made of steel, the blades are made of glass fiber and carbon fiber composite materials, the rated speed of the wind turbine blades is 7.5 rpm, the blade length is 126 meters, the hub center height is 155 meters, the impeller diameter is 260 meters, and the maximum distance between the blade tip and the water surface is 285 meters. A simulation model is established based on this.

[0105] In the electromagnetic simulation software FEKO, since the wind turbine blades are mainly made of fiberglass composite materials, the dielectric constant of the blades is set to about 2.3 during simulation. The materials of the wind turbine hub and tower are mainly set to PEC materials. When the pitch angle is 0° and the azimuth angle of the wind turbine is 0° to 360°, different distances are set according to the location of the wind turbine in the sea area, and the impact of wind turbines at different locations on the RCS echo of the radar is simulated and analyzed. The details are as follows:

[0106] a: The radar transmission frequency is set to 3GHz, and the distance between the radar and the fan blade axis is R = 20km. The simulation diagram of the radar beam irradiating the fan with the azimuth angle is as follows Figure 5 As shown in the figure, the radar beam irradiating the wind turbine changes with the pitch angle. Figure 6 shown.

[0107] from Figure 5-6 It can be found that when the pitch angle remains unchanged, the radar cross-sectional area is forward scattered and backward scattered at 13° and 171°, and the peak value is about 66.48dBsm. When the radar illuminates the side of the wind turbine, that is, when the azimuth angle is 90° and 270°, the radar cross-sectional area has a valley value, and its valley value is about 33.42dBsm. When the azimuth angle remains unchanged, the radar cross-sectional area peaks at about 100.5°, and its peak value is about 61.24dBsm. It can be clearly seen that the attitude of the wind turbine blades has a certain influence on the radar cross-sectional area, and its maximum value appears when the blade rotation plane is perpendicular to the radar ray; the valley value appears when the blade rotation plane is parallel to the radar ray.

[0108] b: The radar transmission frequency is set to 3GHz, and the distance between the radar and the fan blade axis is R = 40km. The simulation diagram of the radar beam irradiating the fan with the azimuth angle is as follows Figure 7 As shown in the figure, the radar beam irradiating the wind turbine changes with the pitch angle. Figure 8 shown.

[0109] from Figure 7-8It can be found that when the pitch angle remains unchanged, the radar cross-sectional area is forward scattered at 0°, and a peak value appears, which is about 46.11dBsm. When the radar illuminates the side of the wind turbine, that is, when the azimuth angle is 90°, the radar cross-sectional area has a valley value, and its valley value is about 20.33dBsm. When the azimuth angle remains unchanged, the radar cross-sectional area is about 95.2°, and the radar cross-sectional area has a peak value, which is about 40.22dBsm. It can be clearly seen that as the distance from the wind turbine to the radar increases, the RCS generated by the wind turbine decreases significantly, and the impact on the radar echo becomes smaller.

[0110] c: The radar transmission frequency is set to 3GHz, and the distance between the radar and the fan blade axis is R = 60km. The simulation diagram of the radar beam irradiating the fan with the azimuth angle is as follows Fig. 9 As shown in the figure, the radar beam irradiating the wind turbine changes with the pitch angle. Fig.10 shown.

[0111] from Figure 9-10 It can be found that when the pitch angle remains unchanged, the radar cross-section area is backscattered at 25° and 170°, with a peak value of about 48.57dBsm. When the radar illuminates the side of the wind turbine, that is, when the azimuth angle is 90° and 270°, the radar cross-section area has a valley value of about 19.28dBsm. When the azimuth angle remains unchanged, the radar cross-section area has a peak value of about 45.53dBsm when it is about 80.2°.

[0112] It can be clearly seen that when the distance from the wind turbine to the radar reaches a certain range, its RCS does not change much, indicating that the RCS value generated by the wind turbine will not decrease with the increase of distance; at this time, the RCS echo of the wind turbine has little effect on the radar detection performance and will not cover the actual radar detection target echo. There is no need to revise the proposed offshore wind farm construction plan.

[0113] It should be noted that the modules are arranged in a stream layout, which is only one embodiment of the present invention. Other arrangements may also be adopted, and the present invention is not limited thereto.

[0114] The beneficial effects of the above embodiment are as follows:

[0115] Based on the analysis results of the impact of the proposed offshore wind turbines at different locations on the radar's RCS echo in step 3, this analysis method guides the radar detection correction or the construction plan correction of the proposed offshore wind farm before the construction of the offshore wind farm, so as to avoid the impact of the echo characteristics of the established offshore wind farm on the active radar detection performance.

[0116] Fig.11This is a structural block diagram of a device for analyzing the impact of wind turbine echo characteristics on radar in a proposed offshore wind farm provided by an embodiment of the present invention, the device comprising:

[0117] Establish modules to build the overall model of a single wind turbine;

[0118] A calculation module is used to calculate the radar echo according to the overall model, specifically: calculate the radar echo of the wind turbine blade; calculate the radar echo of the wind turbine tower; add the radar echo of the blade and the radar echo of the tower to obtain the radar echo of the overall model;

[0119] The analysis module is used to analyze the impact of proposed offshore wind turbines at different locations on the radar's RCS echo.

[0120] Fig.11 The functions of each module in the embodiment correspond to the contents in the corresponding method embodiment and will not be repeated here.

[0121] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for analyzing the impact of wind turbine echo characteristics on radar in a proposed offshore wind farm, characterized in that: The following steps are involved: S1: Establish the overall model of a single wind turbine; S2: Calculate the radar echo according to the overall model, specifically: S2.1: Calculate the radar echo of the wind turbine blades; S2.2: Calculate the radar echo of the wind turbine tower; S2.3: adding the radar echo of the blade and the radar echo of the tower to obtain the radar echo of the overall model; S3: Analyze the impact of proposed offshore wind turbines at different locations on the radar RCS echo.

2. The analysis method according to claim 1, characterized in that: The electromagnetic simulation software FEKO is used for simulation analysis.

3. The analysis method according to claim 1, characterized in that: The wind turbine overall model includes the blades and the tower.

4. The analysis method according to claim 1, characterized in that: In step S2, a three-dimensional coordinate system is established with the center point of the blade as the origin O of the coordinate system and the direction perpendicular to the blade rotation plane as the x-axis; then the radar echo of the equivalent scattering point on the overall model of the wind turbine is: In the formula, f c and λ represent the center frequency of the radar transmitting signal and the operating wavelength of the radar respectively, and R is the distance from the equivalent scattering point to the radar.

5. The analysis method according to claim 4, characterized in that: The equivalent scattering point is obtained in the following manner: the wind turbine is triangulated by using a triangular facet method, and the center of the triangular facet is taken as the equivalent scattering point.

6. The analysis method according to claim 4, characterized in that: The distance R from the equivalent scattering point to the radar is calculated as follows: In formula (2), X B , Y B , Z B represents the coordinate scale of the radar in the three-dimensional coordinate system; X Pi , Y Pi , Z Pi Represents the coordinate scale of the equivalent scattering point Pi in the three-dimensional coordinate system.

7. The analysis method according to claim 4, characterized in that: In step S2.1, the echo signal of the entire blade is expressed as: Where L is the length of the blade; f c and λ represent the center frequency of the radar transmission signal and the working wavelength of the radar respectively; L OB represents the distance between the radar and the coordinate origin; δ represents the distance between the blade and the radar line of sight L OS The angle between the two angles is , where cosδ is calculated as: cosδ=cosθ k t sinαsinβ+sinθ k t cosβ; α represents the angle between the projection of the radar line of sight LOS in the XOY plane and the X-axis, β represents the angle between the radar line of sight LOS and the positive direction of the Z-axis; θ k t It represents the angle between the blade and the positive direction of the Y axis, and is calculated as follows: Wherein ω represents the angular velocity of the blade rotation.

8. The analysis method according to claim 7, characterized in that: In the step S2.1, it is also necessary to obtain the radar echo sequence under the blade rotation period.

9. The analysis method according to claim 7, characterized in that: In step S2.2, the tower echo is calculated as follows: Assuming that the tower scattering cross section is in the same plane as the blade, the radar coordinate is B(X B , Y B , Z B ) The radar coordinates after transformation are B'(X B' , Y B' , Z B' ): in, represents the distance from the radar to the origin of the coordinate system; γ represents the angle between the line connecting the radar and the origin of the coordinate system and the XOY plane; The equivalent distance between the scattering point on the tower and the radar is expressed as: The radar echo of the tower is the same at every moment, expressed as: The radar echo of the tower is expressed as: Wherein, H represents the height of the tower.

10. An analysis device for the influence of wind turbine echo characteristics on radar in a proposed offshore wind farm, characterized in that: The analytical method according to any one of claims 1 to 9 is used, comprising: Establish modules to build the overall model of a single wind turbine; A calculation module, used to calculate the radar echo according to the overall model, specifically: calculate the radar echo of the wind turbine blade; calculate the radar echo of the wind turbine tower; add the radar echo of the blade and the radar echo of the tower to obtain the radar echo of the overall model; The analysis module is used to analyze the impact of proposed offshore wind turbines at different locations on the radar's RCS echo.

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