Calculation Method of Plane Gust Factor in Mountainous Areas

Abstract

The present invention discloses a method for calculating the planar gust factor in mountainous areas. The steps include establishing a planar grid; calculating the average terrain elevation based on the planar grid; calculating the canyon surface height based on the planar grid; calculating the mountain peak surface height based on the planar grid; and calculating the grid point gust factor based on the average terrain elevation, the canyon surface height, and the mountain peak surface height. The present invention is applicable to the technical field of power grid wind disaster prevention. By establishing a correlation model between the gust factor and terrain undulation, fully considering the influence of terrain undulation on the gust factor, calculating the planar distribution of the gust factor under different atmospheric motion backgrounds, it can give early warnings for possible strong gust events, which helps to manage the operation risks of the power grid targeted and improve the operation reliability level of the power system.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid wind disaster prevention, and specifically relates to a calculation method for the planar gust factor in mountainous areas. Background Art

[0002] The research on gust factors mainly considers ground roughness and height above the ground. The "Load Code for Building Structures" classifies ground roughness categories into four types: A, B, C, and D, which are: A, off-shore sea surfaces and islands, coasts, lake shores, and desert areas; B, fields, villages, jungles, hills, and towns with sparse houses; C, urban areas with dense building clusters; D, urban areas with dense building clusters and high-rise houses. Reference values for gust factors at different heights are given.

[0003] However, the existing calculation methods for gust factors only consider roughness and height above the ground, and do not consider the influence of terrain undulation on gust factors, making it difficult to warn of possible strong gust events, resulting in an increase in power grid operation risks and a reduction in the operational reliability of the power system. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a calculation method for the planar gust factor in mountainous areas.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A calculation method for the planar gust factor in mountainous areas, the steps including:

[0007] Establish a planar grid;

[0008] Based on the planar grid, calculate the average terrain elevation;

[0009] Based on the planar grid, calculate the canyon surface height;

[0010] Based on the planar grid, calculate the mountain peak surface height;

[0011] Based on the average terrain elevation, canyon surface height, and mountain peak surface height, calculate the grid point gust factor.

[0012] Preferably, the establishment of the planar grid uses the Lambert conformal conic projection to project the area of interest onto a 1 km × 1 km grid.

[0013] Preferably, the calculation of the average terrain elevation uses refined terrain elevation data to obtain the average terrain elevation data of each grid point. The terrain elevation of the i-th grid point is represented by z i denoted.

[0014] Preferably, the method for calculating the height of the canyon surface is to define the height of the canyon surface at each grid point as the altitude of the canyon adjacent to that point; the height of the canyon surface at the i-th grid point The calculation method is as follows:

[0015] First, calculate the minimum value of the terrain elevation around the i-th grid point

[0016] The calculation formula is

[0017] where x i , y i are the east-west and north-south coordinates of the i-th grid point respectively; R valley is taken as 5 km;

[0018] is a two-dimensional moving average with a radius of R valley :

[0019] The calculation formula is

[0020] Preferably, the method for calculating the height of the mountain peak surface is: define the height of the mountain peak surface at each grid point as the altitude of the mountain peak adjacent to that point, and the height of the mountain peak surface at the i-th grid point The calculation method is as follows:

[0021] First, calculate the maximum value of the terrain elevation around the i-th grid point

[0022] The calculation formula is

[0023] where x i , y i are the east-west and north-south coordinates of the i-th grid point respectively, and R summit is taken as 3 km;

[0024] is a two-dimensional moving average with a radius of R summit :

[0025] The calculation formula is

[0026] Preferably, the calculation formula for the grid point gust factor is:

[0027]

[0028] where the coefficients a, b, c, and d are obtained by fitting the historical observed gust factors.

[0029] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0030] The present invention provides a method for calculating the planar gust factor in mountainous areas. By establishing a correlation model between the gust factor and terrain undulation, fully considering the influence of terrain undulation on the gust factor, calculating the planar distribution of the gust factor under different atmospheric motion backgrounds, it can warn of possible strong gust events, which helps to target the control of power grid operation risks and improve the operation reliability level of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flowchart of the method for calculating the planar gust factor in mountainous areas of the present invention;

[0032] Figure 2 is a distribution map of the gust factor in the Beijing area calculated by using the technical method of the present invention in Preferred Embodiment 2 of the present invention;

[0033] Figure 3 is a planar distribution map of the gust factor calculated by the ground observation stations in the Beijing area during strong winds in Preferred Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following further describes the specific implementation manners of the method for calculating the planar gust factor in mountainous areas of the present invention in conjunction with the attached Figures 1-3 , drawings. The method for calculating the planar gust factor in mountainous areas of the present invention is not limited to the descriptions of the following embodiments.

[0035] Embodiment 1:

[0036] This embodiment gives the specific structure of the method for calculating the planar gust factor in mountainous areas, as Figure 1 shown, the steps include:

[0037] Establish a planar grid;

[0038] Based on the planar grid, calculate the average terrain elevation;

[0039] Based on the planar grid, calculate the canyon surface height;

[0040] Based on the planar grid, calculate the mountain peak surface height;

[0041] Based on the average terrain elevation, canyon surface height, and mountain peak surface height, calculate the grid point gust factor.

[0042] Further, establishing a planar grid is to project the area of interest onto a 1 km × 1 km grid by using the Lambert conformal conic projection.

[0043] Further, calculating the average terrain elevation is to use refined terrain elevation data to obtain the average terrain elevation data of each grid point, and the terrain elevation of the i-th grid point is represented by z i for indication.

[0044] Specifically, the method for calculating the canyon surface height is to define the canyon surface height of each grid point as the elevation of the canyon adjacent to that point; the canyon surface height of the i-th grid point The calculation method is as follows:

[0045] First, calculate the minimum value of the terrain elevation around the i-th grid point

[0046] The calculation formula is

[0047] where x i , y i are the east-west and north-south coordinates of the i-th grid point respectively, and R valley is taken as 5 km; is a two-dimensional moving average with a radius of R valley :

[0048] The calculation formula is

[0049] Specifically, the method for calculating the mountain peak surface height is: define the mountain peak surface height of each grid point as the elevation of the mountain peak adjacent to that point, and the mountain peak surface height of the i-th grid point The calculation method is as follows:

[0050] First, calculate the maximum value of the terrain elevation around the i-th grid point

[0051] The calculation formula is

[0052] where x i , y i are the east-west and north-south coordinates of the i-th grid point respectively, and R summit is taken as 3 km;

[0053] is a two-dimensional moving average with a radius of R summit ,

[0054] The calculation formula is

[0055] Specifically, the calculation formula for the grid point wind coefficient is:

[0056]

[0057] where the coefficients a, b, c, and d are obtained by fitting the historical observed gust coefficients.

[0058] By adopting the above technical solutions:

[0059] First, using the Lambert conformal conic projection, project the area of interest onto a 1 km × 1 km grid to establish a planar grid;

[0060] Next, using refined terrain elevation data, obtain the average terrain elevation data for each grid point, and calculate the terrain elevation z of the i-th grid point i ;

[0061] Then, define the canyon surface height of each grid point as the altitude of the canyon adjacent to that point, and calculate the canyon surface height of the i-th grid point

[0062] After that, define the peak surface height of each grid point as the altitude of the peak adjacent to that point, and calculate the peak surface height of the i-th grid point

[0063] Finally, substitute the terrain elevation z of the i-th grid point i , the canyon surface height of the i-th grid point and the peak surface height of the i-th grid point into the calculation formula of the grid point wind coefficient to obtain the grid point wind coefficient.

[0064] Example 2:

[0065] As Figure 2 and Figure 3 shown, the calculation method of the planar gust coefficient in mountainous areas includes:

[0066] Scheme 1: Using the technical method of the present invention to calculate the gust coefficient distribution in the Beijing area as shown in Figure 2 ;

[0067] Scheme 2: Based on the data of 150 ground observation stations in the Beijing area, select the time periods with relatively high wind speeds to calculate the gust coefficient planar distribution as shown in Figure 3 ;

[0068] By comparing the results of the two schemes, the following conclusions are obtained:

[0069] The gust coefficient distribution maps obtained by the two schemes are relatively similar in terms of distribution pattern and magnitude. The method of the present invention simulates the high-value area of the gust coefficient in the valleys in the western and northern mountainous areas of Beijing, which coincides with most of the ground observation stations located in the valleys. The method slightly overestimates the gust coefficient in the plain area. Considering that this method needs to be applied in the field of power grid wind disaster prevention, slightly overestimating the gust coefficient in the plain area just meets the defense requirements of the power grid in the plain area for strong gusts.

[0070] In summary, the present invention provides a method for calculating the planar gust factor in mountainous areas. By establishing a correlation model between the gust factor and terrain undulations, fully considering the influence of terrain undulations on the gust factor, and calculating the planar distribution of the gust factor under different atmospheric motion backgrounds, it is possible to warn of possible strong gust events, which helps to specifically control the operation risks of the power grid and improve the operation reliability level of the power system.

[0071] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. Calculation method for planar gust factor in mountainous areas, characterized in that , the steps include: Establish a planar grid; Based on the planar grid, calculate the average terrain elevation; Based on the planar grid, calculate the canyon surface height; Based on the planar grid, calculate the mountain peak surface height; Based on the average terrain elevation, canyon surface height and mountain peak surface height, calculate the grid point gust factor; The calculation of the average terrain elevation uses refined terrain elevation data to obtain the average terrain elevation data for each grid point. The terrain elevation of the i-th grid point is represented by ; The method for calculating the canyon surface height is to define the canyon surface height of each grid point as the altitude of the canyon adjacent to that point; the canyon surface height of the i-th grid point The calculation method is as follows: First, calculate the minimum value of the terrain elevation around the i grid point , The calculation formula is ; where xi and yi are the east-west and north-south coordinates of the i-th grid point, respectively; Take 5 km; For a two-dimensional moving average with a radius of : The calculation formula is ; The method for calculating the height of the mountain peak surface is as follows: Define the height of the mountain peak surface of each grid point as the altitude of the mountain peak adjacent to this point. The height of the mountain peak surface of the i-th grid point The calculation method is as follows: First, calculate the maximum value of the terrain elevation around the i grid point , The calculation formula is ; where \(x_i\) and \(y_i\) are the east-west and north-south coordinates of the \(i\)-th grid point, respectively, Take 3 km; For a two-dimensional moving average with a radius of ​ The calculation formula is ; The calculation formula for the grid point gust factor is: where the coefficients a, b, c, d are obtained by fitting the historical observed gust factors.

2. The calculation method for planar gust factor in mountainous areas according to claim 1, characterized in that: The establishment of the planar grid uses the Lambert conformal conic projection to project the area of interest onto a 1km×1km grid.

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