CN113111611A

CN113111611A - Typhoon disaster prediction method, device and storage medium

Info

Publication number: CN113111611A
Application number: CN202110515732.4A
Authority: CN
Inventors: 张晓东
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2021-05-12
Filing date: 2021-05-12
Publication date: 2021-07-13

Abstract

The scheme discloses a typhoon disaster prediction method, which comprises the following steps: acquiring topographic data including a target wind power plant and a peripheral area and position coordinate data of a target wind turbine generator in the wind power plant; selecting a basic terrain area for CFD simulation calculation based on the position of the target wind turbine generator in the target wind power plant; selecting a plurality of calculation domain terrains with rectangular horizontal projections, wherein the calculation domain terrains include the basic terrain area for CFD simulation calculation; taking the center of a rectangle obtained by horizontal projection of a basic terrain area as a circle center, and dividing a circumferential space area around the circle center into fan-shaped space areas with equal angles; selecting a fan-shaped space area corresponding to the wind direction of the typhoon incoming flow based on the wind direction center value of the typhoon incoming flow, and determining a calculation domain for carrying out CFD simulation calculation based on the selected fan-shaped space area. The method solves the problem that the boundary conditions of the side surfaces of the calculation domain can not be reasonably set when the wind direction of the incoming flow changes along the height of a single rectangular terrain calculation domain.

Description

Typhoon disaster prediction method, device and storage medium

Technical Field

The invention relates to engineering application of Computational Fluid Dynamics (CFD) technology in the fields of wind engineering and wind power generation, in particular to a typhoon disaster prediction method, a device and a storage medium.

Background

The application of micro-scale atmospheric boundary layer flow simulation calculation in the fields of wind engineering, wind power generation, particularly wind resource analysis in complex terrain areas is common by utilizing a Computational Fluid Dynamics (CFD) method, and the method is a main technical means adopted by micro-site selection of a wind power plant. For wind resource analysis of a wind power plant, CFD simulation calculation of an atmospheric boundary layer needs to consider a plurality of different wind directions or fan-shaped areas, 16-32 fan-shaped areas are generally adopted, and the wind direction of each fan-shaped area is represented by the central wind direction of the fan-shaped area. The calculation domain is usually selected to be an area including a wind power plant and having a rectangular horizontal projection, and the side length of the rectangle is several kilometers to tens of kilometers. As shown in fig. 1A, the computation field is a space region where air flows, the bottom surface of the computation field is a topographic curved surface, four side surfaces are vertical planes, and the top surface is a horizontal plane. The micro-scale atmospheric boundary layer flow calculation assumes that the periphery of a selected calculation domain is flat terrain, the incoming flow condition of a calculation domain inlet is the incoming flow of the flat terrain, the incoming flow of the atmospheric boundary layer can be any wind direction, and also can only consider the wind directions of different sectors. As shown in fig. 1B, the graph boundary in the figure is actually a vertical plane of the calculation domain boundary, under the condition of the incoming flow of the general atmospheric boundary layer, the wind direction of the incoming flow is determined and does not change with the height, under the condition that the wind direction of the incoming flow is not perpendicular to a certain side, two sides are always inlets (the interface of the atmosphere flowing into the calculation domain), and two opposite sides are outlets (the interface of the atmosphere flowing out of the calculation domain). For any incoming wind direction, the two sides at the upstream are selected as inlets, the two sides at the downstream are selected as outlets, and boundary condition attributes (flow inlets or outlets) are easy to set.

However, in the micro-scale CFD simulation calculation of the typhoon atmospheric boundary layer, the boundary condition setting mode can encounter problems. Typhoon is a tropical cyclone, which typically affects hundreds of kilometers in a square circle. The CFD simulation calculation of the typhoon atmospheric boundary layer of the wind power plant scale is the micro-scale flow field calculation of the weather process with the typhoon passing through as the background. Typhoon landing is frequent in the southeast coastal areas of China, the system is a very destructive weather system and a typical disastrous weather process, and certainly, the typhoon which does not reach the destruction level can also be a very good power generation resource. In the fields of wind engineering and wind power generation, the CFD simulation technology is utilized to calculate the flow of the atmospheric boundary layer in a complex terrain region of a typhoon, and the method has important significance for safety evaluation and design optimization of buildings, facilities, wind turbine generators and the like. The typhoon atmospheric boundary layer flow is obviously different from the atmospheric boundary layer flow considered by the general wind resource calculation, particularly, the low-pressure area of the near-ground typhoon center has strong internal absorption effect, and the intensity of the internal absorption effect changes along with the height, so that the typhoon atmospheric boundary layer incoming flow of the wind power plant calculation area boundary not only needs to consider the change of the wind speed along the height, but also needs to consider the change of the wind direction along the height even under the condition of flat terrain or sea surface. In the height range concerned by engineering, not only the wind speed changes along the height, but also the wind direction changes along the height significantly in the typhoon atmosphere boundary layer, and the calculation model and the measured data show that the wind direction changes possibly to 30 degrees in the height range of 500 meters, and the wind direction changes possibly to 45 degrees in the height range of 1000 meters, and fig. 1C shows the changes of the wind direction along the height. Because the calculation domain horizontal rectangular projection of the general wind farm flow field CFD simulation calculation is adopted, the calculation domain boundary attribute setting is easy to cause ambiguity under the condition that the incoming flow changes along the height, as shown in fig. 1D, the outer normal direction of the calculation domain vertical boundary plane respectively points to the east, south, west and north directions, wherein the east side interface is pure inflow, the west side surface is pure outflow, the top of the north side interface is inflow, the bottom is outflow, the top of the south side interface is outflow, and the bottom is inflow, if the inlet and outlet boundary conditions of the wind farm flow field CFD simulation calculation domain are still set in the manner of the incoming flow of the common atmospheric boundary layer, the inflow and outflow flow conditions may occur at different heights of the same side, and it is difficult to set the boundary conditions according to the inlet or outlet. The flow field in the calculation domain is mainly determined by the flow conditions at the inlet boundary, and the outflow at the inlet boundary is not favorable for the convergence of the CFD calculation process, and can also result in that a reasonable result cannot be obtained.

Disclosure of Invention

One purpose of the scheme is to provide a typhoon disaster prediction method, which accurately predicts the wind speed and the wind direction of a wind turbine point location by setting the calculation domain structure and the attribute of a vertical boundary of an atmospheric boundary layer microscale CFD simulation calculation when logging in a typhoon crossing wind power plant, so that the risk of typhoon damage to the wind turbine is evaluated.

A second object of the present invention is to provide a typhoon disaster prediction device.

A third object of the present solution is to provide a readable storage medium.

In order to achieve the purpose, the scheme is as follows:

a typhoon disaster prediction method, the method comprising:

determining a calculation domain for performing CFD simulation calculation based on the terrain elevation data of a target wind power plant and a peripheral area, the position coordinate data of a target wind turbine generator in the wind power plant and the wind direction central value of the incoming flow of the typhoon;

performing typhoon CFD simulation calculation based on the determined calculation domain, and evaluating typhoon disasters based on the calculation result;

the bottom surface of the computational domain for performing CFD simulation calculation is computational domain terrain, the top surface is projection of the computational domain terrain on a horizontal plane above the computational domain terrain and higher than the thickness of the boundary layer of the typhoon atmosphere, and the side surfaces are four vertical planes.

Preferably, the method further comprises:

selecting a basic terrain area which is subjected to CFD simulation calculation and has a rectangular horizontal projection and a plurality of reference terrain areas which have a rectangular horizontal projection in the target wind power plant based on the position of the target wind turbine generator;

obtaining a first type of calculation domain rectangle based on the basic terrain area, and obtaining a second type of calculation domain rectangle based on the reference terrain area;

obtaining a first type of calculation domain based on the first type of calculation domain rectangles and the obtained terrain elevation data, and obtaining a second type of calculation domain based on the second type of calculation domain rectangles and the obtained terrain elevation data;

the basic terrain area is horizontally projected to obtain a rectangle which is a basic rectangle, and the central lines of the basic rectangle are in the east-west direction and the south-north direction;

and a rectangle obtained by horizontally projecting the reference terrain area is a reference rectangle, and two central lines of the reference rectangle and two central lines of the basic rectangle have included angles with a certain angle.

Preferably, the boundary of the basic rectangle is extended in parallel according to a basic preset distance to obtain a first type of calculation domain rectangle;

and carrying out parallel extension on the boundary of the reference rectangle according to a reference preset distance to obtain a second type of calculation domain rectangle including the basic rectangle.

Preferably, the method further comprises:

taking the center of a rectangle obtained by horizontal projection of a basic terrain area as a circle center, and dividing a circumferential space area around the circle center into fan-shaped space areas with equal angles;

selecting a sector space area corresponding to the wind direction of the typhoon incoming flow based on the wind direction center value of the typhoon incoming flow;

determining a first type of computational domain and a second type of computational domain for CFD simulation computation based on the selected sector-shaped spatial region.

Preferably, the sector space areas are numbered sequentially in a clockwise direction, and the numbers are consecutive positive integers.

Preferably, when the sum of the number of the base terrain areas and the reference terrain areas is N, the number of the sector space areas is 4N, where N is a positive integer from 2 to 8.

Preferably, when the calculation domain is multiple, the included angle between two center lines of the calculation domain rectangle obtained by horizontal projection of each calculation domain and two center lines of the adjacent calculation domain rectangle is 360/4N degrees, where N is a positive integer from 2 to 8.

Preferably, a basic terrain area which is subjected to CFD simulation calculation and has a rectangular horizontal projection is selected in the target wind power plant based on the position of the target wind turbine generator, and 1 reference terrain area which has a rectangular horizontal projection is selected;

a first type of calculation domain rectangle obtained based on the basic terrain area is a first calculation domain rectangle; a first type of calculation domain obtained based on the first type of calculation domain rectangle is a first calculation domain;

a second type of calculation domain rectangle obtained based on the reference terrain area is a second calculation domain rectangle, and a second type of calculation domain obtained based on the second type of calculation domain rectangle is a second calculation domain;

two central lines of the second calculation domain rectangle and two central lines of the first calculation domain rectangle have an included angle of 45 degrees;

taking the center of a rectangle obtained by horizontal projection of a basic terrain area as a circle center, and dividing a circumferential space area around the circle center into 8 fan-shaped space areas with equal angles;

when the serial number of the sector space region corresponding to the wind direction central value of the typhoon incoming flow is a double number, the calculation domain for performing CFD simulation calculation is a first calculation domain;

and when the number of the sector space region corresponding to the wind direction central value of the typhoon coming flow is singular, the calculation domain for performing CFD simulation calculation is a second calculation domain.

In a second aspect, the present application provides a typhoon disaster prediction apparatus, comprising:

the data acquisition unit is used for acquiring topographic data of a target wind power plant and a peripheral area, position coordinate data of a target wind turbine generator in the wind power plant and wind direction data of typhoon incoming flow;

the data analysis unit is used for determining a calculation domain for performing CFD simulation calculation based on the acquired topographic elevation data of the target wind power plant and the peripheral area, the position coordinate data of a target wind turbine generator in the wind power plant and the wind direction central value of the incoming flow of the typhoon;

In a third aspect, the application provides a computer-readable storage medium having a computer program stored thereon, which, when being executed by a processor, carries out the steps of the method according to any one of the preceding claims.

The scheme has the following beneficial effects:

the invention provides a typhoon disaster prediction method, which is characterized in that through the calculation domain structure of atmospheric boundary layer micro-scale CFD simulation calculation and the attribute setting of a vertical boundary when a typhoon crosses a wind power plant, on the basis of obtaining terrain elevation mapping data and mesoscale typhoon meteorological pattern forecast data or typhoon measurement data, N calculation domains (called rectangle calculation domains for short) with horizontal projection as rectangles are arranged, for any typhoon incoming flow wind condition considering the wind direction along the height change, under the condition that the wind direction along the height change of the typhoon is within 90 degrees multiplied by 1-1/N, one rectangle calculation domain always satisfies that two adjacent sides are pure inflow and the other two opposite sides are pure outflow, the problem that the boundary conditions of the calculation domains can not be reasonably set when the incoming flow changes along the wind direction in a single rectangle calculation domain is solved, meanwhile, the core concerned areas of the plurality of calculation domain terrains are ensured to be completely the same, and the flow field analysis of the core concerned areas is not influenced by the used calculation domains. The number N of rectangular computation domains is typically 2 to 8, with N being 2 being the most common case.

Drawings

In order to illustrate the implementation of the solution more clearly, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the solution, and that other drawings may be derived from these drawings by a person skilled in the art without inventive effort.

FIG. 1A is a schematic diagram of a computational domain and an incoming flow of a common atmospheric boundary layer adopted in CFD simulation of a wind power plant flow field;

FIG. 1B is a top view of a computational domain used for CFD simulation of a general wind farm flow field;

FIG. 1C is a schematic diagram of a computational domain and an incoming flow of a typhoon boundary layer adopted in CFD simulation of a wind farm in general;

FIG. 1D is a schematic diagram of ambiguity caused by setting of boundary attributes of a computational domain in case of variation of incoming flow along height by using a computational domain horizontal rectangular projection of CFD simulation of a general wind farm flow field

FIG. 2 is a flow chart of a method for typhoon disaster prediction;

FIG. 3 is a schematic view of a typhoon disaster prediction device;

FIG. 4A is a flow chart of a wind farm flow field CFD simulation calculation domain adopting a double-rectangle calculation domain for disaster prediction;

FIG. 4B is a schematic diagram showing a relationship between a rectangular horizontal projection of a dual-rectangular calculation domain terrain of a wind farm flow field CFD simulation calculation domain and a rectangular horizontal projection of a basic terrain area;

FIG. 4C is a schematic diagram of a selection method of a CFD simulation calculation domain of a flow field of a wind farm under an incoming flow condition of a typhoon boundary layer;

FIG. 5 is a schematic view of a sector to which a center value of a typhoon direction belongs;

FIG. 6 is a diagram illustrating a selection method of a base rectangle and a first computation domain rectangle;

FIG. 7 is a schematic diagram of a selection manner of a reference rectangle, a second calculation domain rectangle and all terrain area rectangles;

FIG. 8 is a schematic view of the wind directions at the center values of the typhoon wind direction of 351, 10 and 20;

fig. 9 is a schematic diagram of a relationship between coordinates of a wind turbine generator or other points of interest, a base rectangle P, a base rectangle center point C, a first calculation domain rectangle G, and a second calculation domain rectangle Q.

Detailed Description

Embodiments of the present solution will be described in further detail below with reference to the accompanying drawings. It is clear that the described embodiments are only a part of the embodiments of the present solution, and not an exhaustive list of all embodiments. It should be noted that, in the present embodiment, features of the embodiment and the embodiment may be combined with each other without conflict.

The terms "first," "second," and the like in the description and in the claims, and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The inventor of the application finds that the typhoon atmospheric boundary layer flow is significantly different from the atmospheric boundary layer flow considered by the general wind resource calculation, particularly, the low-pressure area near the center of the typhoon has strong internal suction effect, and the intensity of the internal suction effect changes with the height, so that the typhoon atmospheric boundary layer incoming flow at the boundary of the wind power plant calculation area needs to consider not only the change of the wind speed along the height but also the change of the wind direction along the height even under the condition of flat terrain or sea surface.

Therefore, the inventor of the present application proposes to construct a computation domain for performing CFD simulation computation on the basis of a terrain area of interest, the bottom surface of the constructed computation domain being a computation domain terrain projected horizontally as a rectangle, the top surface of the computation domain being a projection of the computation domain terrain on a horizontal plane above it above the thickness of the boundary layer of the typhoon atmosphere, and the side surfaces of the computation domain being four vertical planes. The horizontal projection of the constructed calculation domain on the ground, the horizontal projection of the selected calculation domain terrain on the ground and the horizontal projection of the calculation domain top surface on the ground are the same. In the present embodiment, unless otherwise specified, the horizontal projection is an orthographic projection on the ground level.

In order to overcome the defects of a single rectangular calculation domain, a plurality of calculation domains are simultaneously constructed for simulation calculation, and the typhoon disaster is predicted and evaluated based on the results of the simulation calculation of the plurality of calculation domains.

As shown in fig. 2A and 2B, a typhoon disaster prediction method includes the following steps:

s100, determining a calculation domain for CFD simulation calculation based on terrain elevation data of a target wind power plant and a peripheral area, position coordinate data of a target wind turbine generator in the wind power plant and a wind direction central value of a typhoon incoming flow;

the bottom surface of a computational domain for performing CFD simulation calculation is computational domain terrain, the top surface is projection of the computational domain terrain on a horizontal plane above the computational domain terrain and higher than the thickness of a typhoon atmospheric boundary layer, and the side surfaces are four vertical planes. S100 further comprises:

s111, selecting a basic terrain area which is subjected to CFD simulation calculation and is horizontally projected to be rectangular and a plurality of reference terrain areas which are horizontally projected to be rectangular in the target wind power plant based on the position of the target wind turbine generator;

in the scheme, only 1 basic terrain area is selected, and a plurality of reference terrain areas can be selected;

s112, obtaining a first type of calculation domain rectangle based on the basic terrain area, and obtaining a second type of calculation domain rectangle based on the reference terrain area;

further, performing parallel epitaxy on the boundary of the basic rectangle according to a basic preset distance to obtain a first type of calculation domain rectangle; extending the boundary of the reference rectangle in parallel according to a reference preset distance to obtain a second type of calculation domain rectangle including the basic rectangle;

s113, obtaining a first type of calculation domain based on the first type of calculation domain rectangle and the obtained terrain elevation data, and obtaining a second type of calculation domain based on the second type of calculation domain rectangle and the obtained terrain elevation data;

wherein, the rectangle obtained by the horizontal projection of the basic terrain area is a basic rectangle, and the central lines of the basic rectangle are in the east-west direction and the south-north direction;

S114, taking the center of a rectangle obtained by horizontal projection of the basic terrain area as a circle center, and dividing a circumferential space area around the circle center into fan-shaped space areas with equal angles;

determining a calculation domain for CFD simulation calculation based on the selected fan-shaped space region;

the computing domains include the first class of computing domains and the second class of computing domains.

In step S114, the sector space areas are numbered sequentially in a clockwise direction, and the numbers are consecutive positive integers; the direction of the angle bisector of each sector space region has the same measuring reference.

When the sum of the number of the base terrain areas and the reference terrain areas is N, the number of the sector space areas is 4N, and N is a positive integer from 2 to 8.

When the calculation domains are multiple, the included angle between two central lines of a calculation domain rectangle obtained by horizontal projection of each calculation domain and two central lines of an adjacent calculation domain rectangle is 360/4N degrees, wherein N is a positive integer from 2 to 8.

S200, typhoon CFD simulation calculation is carried out based on the determined calculation domain, and typhoon disasters are evaluated based on the calculation result.

The method is further explained below with reference to the drawings, taking two calculation domains as an example. If two calculation domains are planned to be constructed simultaneously, the angle between the center line of each rectangle obtained by horizontal projection of the two calculation domains and the center line of the other rectangle is 45 °. Under the condition that the variation of the wind direction of the typhoon incoming flow along the height is within 45 degrees (limit value), for the typhoon incoming flow wind condition that the wind direction varies along the height, one rectangular calculation domain always meets the condition that two adjacent sides are pure inflow and the other two opposite sides are pure outflow, the problem that the boundary conditions of the sides of the calculation domains cannot be reasonably set when the wind direction of the incoming flow varies along the height in a single rectangular calculation domain is solved, the core attention areas of the two calculation domains are completely the same, and the flow field analysis of the core attention areas is not influenced by the used rectangular calculation domains.

In one embodiment, it is first necessary to obtain a wide range (e.g., nationwide or worldwide) of terrain elevation data for an area including a wind farm, which may be obtained by satellite mapping or field mapping; the horizontal resolution of the acquired topographic data is up to 30 m; for single determined wind power plant flow field calculation, only the topographic data comprising the target wind power plant and the peripheral area can be obtained, and the distance between the topographic data boundary and the boundary of the wind power plant is more than 10 km; secondly, obtaining position coordinate data of a target wind turbine generator in a target wind power plant, wherein the position coordinate of the target wind power plant is a basis for determining the range of the wind power plant, and the position coordinate of the target wind turbine generator is a target concerned by the CFD flow field calculation of the typhoon; and the position coordinates of the target wind power plant and the target wind turbine generator are expressed by longitude and latitude.

And selecting a basic terrain area for CFD simulation calculation on the basis of longitude and latitude position coordinates and hub height of a known target wind turbine generator or other places needing attention, such as the longitude and latitude coordinates of the position of a wind measuring tower or other buildings, in the topographic range of the wind power plant scale. After the basic terrain area is selected, determining a reference terrain area, and determining a first calculation domain rectangle and a second calculation domain rectangle based on the selected basic terrain area and the reference terrain area; and meanwhile, selecting a first calculation domain and a second calculation domain for CFD simulation calculation according to forecast data given by a certain horizontal output node in the range of the wind power plant region or measurement data in the range of the wind power plant based on a Weather Research and Forecasting Model (WRF mode). According to the scheme, forecast data given by a certain horizontal output node in a wind power plant area range or measurement data in the wind power plant range based on a mesoscale typhoon forecasting mode are wind speed and wind direction data of a plurality of discrete space points along a straight line perpendicular to a horizontal plane, and wind direction central values and wind direction variation ranges of the discrete space points are calculated;

the horizontal projection of the selected basic terrain area which needs to meet the requirement of the terrain area is a rectangle with the central line in the east-west or south-north direction, the rectangle obtained after the horizontal projection of the basic terrain area is a basic rectangle P, and the central line of the basic rectangle P is superposed with the local longitude and latitude lines of the wind power plant and is a line extending in the south-north and east-west directions. The terrain area corresponding to the basic rectangle P is a core concern area of wind power plant flow field calculation.

After a basic terrain area is selected, a reference terrain area is selected in the range of the wind power plant, a rectangle formed by the reference terrain area after horizontal projection is called a reference rectangle A, two straight lines 1 and line2 are made through the central point C of the basic rectangle P, and the line1 is translated to the south-east side of all wind turbines and the attention point on the straight lines; translating line1 southward to the northwest side of the straight line with all wind turbines and points of interest; translating line2 north to the south-west side of the straight line where all wind turbines and points of interest reside; line2 is translated south to all wind turbines and points of interest are on the northeast side of the line. And an area enclosed by the four straight lines after translation is a reference rectangle A. As a preferred embodiment, the center line of the reference rectangle a forms an angle of 45 ° with the longitude and latitude line of the location of the wind farm, i.e. with the north-south direction or the east-west direction, respectively.

As shown in fig. 4B and 4C, the boundary of the basic rectangle P is extended in parallel to obtain a first calculation domain rectangle G according to the basic preset distance. And extending the boundary of the reference rectangle A outwards, wherein the extended distance is greater than or equal to the reference preset distance, and the extended rectangle at least comprises a basic rectangle P, so that the extended rectangle is a second calculation domain rectangle Q. A terrain area with a rectangular horizontal projection is selected in the range of the wind power plant, the horizontal projection of the terrain area is called as an all terrain area rectangle, and the all terrain area rectangle is a minimum rectangle which is centered at a center point C of a basic rectangle P, has a center line coincident with the center line of the basic rectangle P and comprises a first calculation domain rectangle and a second calculation domain rectangle. The basic preset distance includes the east-west epitaxial distance delta_xAnd a north-south epitaxial distance delta_yThe reference preset distance is a second extension distance

The first calculation domain rectangle G is a horizontal projection of the first calculation domain terrain, the bottom surface of the first calculation domain is the first calculation domain terrain, the second calculation domain rectangle Q is a horizontal projection of the second calculation domain terrain, and the bottom surface of the second calculation domain is the second calculation domain terrain.

When two calculation domains are used, one of the two calculation domains is a first calculation domain obtained from the basic terrain area, and the other is a second calculation domain obtained from the reference terrain area, and the total number of the calculation domains is 2, as shown in fig. 5, the wind direction is divided into 8 sector-shaped space regions, the 8 sector-shaped space regions are sequentially numbered in the clockwise direction, and the number of the sector-shaped space region in the due north direction is 1. The angle of the center of each sector space region is 45 degrees, and the directions of the bisectors of the angles from the sector space region 1 to the sector space region 8 are respectively 0 degree, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees and 315 degrees. The direction of the angular bisector of the sector spatial region is in accordance with the direction reference corresponding to the center value of the wind direction of the incoming typhoon flow, and if the direction corresponding to the center value of the wind direction of the incoming typhoon flow is the due north direction, the direction corresponding to the center value of the wind direction of the incoming typhoon flow is 0 °, and if the direction corresponding to the center value of the wind direction of the incoming typhoon flow is the due east direction, the direction corresponding to the center value of the wind direction of the incoming typhoon flow is 90 °. For a specific boundary condition of the typhoon incoming flow, the direction corresponding to the wind direction central value of the typhoon incoming flow is obtained according to the variation range of the wind direction along the height, and the direction corresponding to the wind direction central value of the typhoon incoming flow is the direction of the angular bisector of the angle formed by the variation range of the wind direction of the typhoon incoming flow. For example, if the wind direction of the typhoon coming flow changes from 10 ° to 18 ° with the true north direction being 0 °, the wind direction center value of the typhoon coming flow corresponds to 14 °. If the variation range of the wind direction of the typhoon incoming flow is 358 degrees to 12 degrees, the central value of the wind direction of the typhoon incoming flow is 5 degrees correspondingly. After the wind direction center value is measured, the corresponding sector space region is selected according to the wind direction center value, and for example, if the wind direction center value of the incoming typhoon is between 67.5 ° and 112.5 °, the sector space region with the number 3 is corresponding. For the case where the wind direction center value belongs to the singular sector space region, using a second calculation domain having a second calculation domain rectangle Q as the bottom; for the case where the wind direction center value belongs to the even-numbered sector space region, the first calculation domain with the first calculation domain rectangle G as the bottom surface is used. Selecting a computational domain may also be performed as follows: selecting a sector space area according to the wind direction central value of the typhoon incoming flow, and determining a calculation domain based on the selected sector space area, wherein the step 1 comprises determining the wind direction central value of the typhoon incoming flow; 2. selecting a sector-shaped space region; 3. determining a calculation domain according to the relation between the direction pointed by the vertex angle of the calculation domain rectangle and the direction of the angular bisector of the sector space region; if the wind direction central value of the typhoon coming flow is between 67.5 degrees and 112.5 degrees when two calculation domains are adopted, the typhoon coming flow corresponds to the sector space region with the number of 3; and the directions pointed by the vertex angles of the second calculation domain rectangles Q corresponding to the second calculation domain are 0 °, 90 °, 180 ° and 270 °, the directions pointed by the vertex angles of the second calculation domain rectangles Q correspond to the fan-shaped space regions numbered 1, 3, 5 and 7, respectively, the direction of the wind direction center value of the typhoon incoming flow and the 90 ° direction pointed by the vertex angle of the second calculation domain rectangle Q are both in the fan-shaped space region numbered 3, and the calculation domain corresponding to the fan-shaped space region numbered 3 is the second calculation domain, and therefore, the calculation domain selected based on the wind direction center value of the typhoon incoming flow is the second calculation domain. If there are multiple calculation domains, i.e., multiple reference terrain areas, the calculation domain for performing CFD simulation calculations may be determined according to the method described above.

The entry or exit boundary condition of the computational domain vertical boundary is determined from the wind direction center value. As shown in fig. 4C, the wind direction center value of the incoming flow condition 1 belongs to the 2 nd sector, and the first calculation domain with the first calculation domain rectangle G as the bottom surface is used, the north and east vertical interfaces of the first calculation domain are inflow boundaries, and the south and west vertical interfaces of the first calculation domain are outflow boundaries. And the wind direction central value of the incoming flow condition 2 belongs to the 3 rd sector, a second calculation domain with a second calculation domain rectangle as the bottom surface is used, the northeast and southeast side surfaces of the second calculation domain are inflow boundaries, and the northwest and southwest boundaries of the second calculation domain are outflow boundaries.

In a modified embodiment, the methods of the present application may be used in superposition. For example, 4 rectangular calculation domains can be used on the basis of the concerned terrain area, the included angle between two central lines of a rectangle formed by horizontal projection of each calculation domain and two central lines of an adjacent rectangle is 22.5 degrees, the wind direction can be divided into 16 fan-shaped areas, and each rectangular calculation domain corresponds to the condition that the central value of the wind direction of the incoming flow of one typhoon boundary layer belongs to 4 fan-shaped areas. The ideal limit for allowing the typhoon boundary layer incoming flow to vary along the height is now 67.5 deg..

In the case of using two rectangular computational domains, the method of the present application allows the ideal limit value for the range of variation of the typhoon boundary layer incoming flow along the altitude to be 45 °. In fact, due to the variation of the horizontal wind direction of the typhoon, the allowable variation range of the vertical wind direction can be reduced, and the specific reduction amplitude is related to the relative position of the typhoon center and the wind power field calculation domain. For the wind speed range concerned by engineering, both field measurement and theoretical models show that the variation range of the flowing wind direction of the typhoon boundary layer within 500m of the height along the height is within 30 degrees, so the method of the application can meet the requirement of CFD calculation of the common typhoon boundary layer. The method of the present application can be used overlappingly if it is desired to extend the range of allowable wind direction changes.

The method provides a practical solution for realizing reasonable setting of boundary attributes of a calculation domain, and is easy to realize programming.

As shown in fig. 3, the present embodiment also provides a typhoon disaster prediction device 1 including:

the data acquisition unit 10 is used for acquiring topographic data of a target wind power plant and a peripheral area, position coordinate data of a target wind turbine generator in the wind power plant and wind direction data of a typhoon incoming flow;

the data analysis unit 20 is used for determining a calculation domain for performing CFD simulation calculation based on the acquired topographic elevation data of the target wind power plant and the peripheral area, the position coordinate data of the target wind turbine generator in the wind power plant and the wind direction central value of the typhoon incoming flow;

The present embodiment further provides a computer-readable storage medium. The computer-readable storage medium is a program product for implementing the above-described identification method, which may employ a portable compact disc read only memory (CD-ROM) and include program code, and may be run on a device, such as a personal computer. However, the program product in this embodiment is not limited in this respect, and in this document, a readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

The program product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

A computer readable storage medium may include a propagated data signal with readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A readable signal medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a computer readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as JAvA, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user computing device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., through the internet using an internet service provider).

In order to make the purpose and technical solution of the present application clearer and easier to understand, the present application will be described in further detail with reference to specific embodiments.

The method comprises the following steps: data preparation

Terrain elevation data, such as a national or global terrestrial digital terrain elevation database, including wind farm areas, is first obtained, or mapped. For a wind power plant or other areas needing to examine typhoon crossing influence, longitude and latitude coordinates and UTM coordinates of a wind power generator set or other interested targets (such as buildings, bridges and the like) in the area are acquired, and data related to the area or wind measuring data of a certain place of the area in mesoscale typhoon forecasting mode data. For convenience of description, the following description focuses on only wind turbines, and the ith wind turbine is denoted by Wti. A wind farm is a terrain area that includes all wind turbines. According to the actual situation of the terrain around the wind power plant, the minimum distance between the boundary of the calculation domain and the wind power generator set is determined, and usually 1-5 km can be selected. By delta_xThe horizontal distance between the west boundary of the first calculation domain and the west wind turbine generator in the east-west direction is represented, and the horizontal distance between the east boundary of the first calculation domain and the east wind turbine generator in the east-west direction is also represented. By delta_yThe horizontal distance between the north boundary of the first calculation domain and the north-south wind turbine generator in the south-north direction is represented, and the horizontal distance between the south boundary of the first calculation domain and the south-south wind turbine generator in the south-north direction is also represented. Delta_x、δ_yAlso known as epitaxyDistance.

The dots in FIG. 6 are horizontal projections of the wind turbines within the wind farm. The central line and the side of the basic rectangle P are respectively the true south and true north direction and the true east and true west direction, and are respectively superposed with the longitude line and the latitude line of the location of the wind power plant. The base rectangle P is the smallest rectangular area that includes all wind turbines. The influence of the terrain around the basic rectangle P needs to be considered in the flow field of the wind power plant, and the boundary extends to the east and the west by a distance delta on the basis of the basic rectangle P_xExtend delta to south and north_yA first computation domain rectangle G can be obtained, and the east-west length of the first computation domain rectangle G is L_x1The north and south length is L_y1. The center points of the base rectangle P and the first calculation domain rectangle G are C, delta_xThe horizontal distance between the west boundary of the first calculation domain and the west-most wind turbine generator is represented, and the horizontal distance between the east boundary of the first calculation domain and the east-most wind turbine generator is also represented. Delta_yThe horizontal distance between the north boundary of the first calculation domain and the north-most wind turbine is represented, and the horizontal distance between the south boundary of the first calculation domain and the south-most wind turbine is also represented. Delta_x、δ_yAlso known as the epi-distance.

Step two: determining a basic rectangle P corresponding to the attention area

Taking a wind turbine as an example, referring to fig. 6, a basic rectangle P can be determined according to coordinates of the wind turbine, a central point of the rectangular area is represented by C (═ C), and 4 vertexes are represented by P, respectively₁、P₂、P₃、P₄And (4) showing. The minimum value, the maximum value and the middle value of the latitude coordinate of the wind turbine are respectively represented by slat, nlat and plat, and the minimum value, the maximum value and the middle value of the longitude coordinate of the wind turbine are respectively represented by wlon, elon and plon. The median value here means the average of the maximum value and the minimum value. The longitude and latitude coordinates and the local rectangular coordinate system coordinates (UTM projection coordinates) of the 4 vertices and the center point of the basic rectangle P are respectively expressed as

P₁(slat，elon)，

P₂(nlat，elon)，

P₃(nlat，wlon)，

P₄(slat，wlon)，

C(plat，plon)，

The coordinates of the rectangular coordinate system are specified as follows: the horizontal direction from west to east is the x-axis, the horizontal direction from south to north is the y-axis, and the vertical direction is the z-axis. A z coordinate of 0 for the 4 vertices and the center point of the base rectangle P indicates that the point is a projection of a point on the actual terrain on a horizontal plane.

Step three: and determining a first calculation domain rectangle G corresponding to the first calculation domain.

Referring to fig. 6, δ is respectively expanded to east and west on the basis of the basic rectangle P_xRespectively extending delta to north and south_yTo obtain a first computation domain rectangle G, whose vertices are respectively G₁、G₂、G₃、G₄Representing, respectively, vertex coordinates by vectors

Represents:

x_G1＝x_P1+δ_x，y_G1＝y_P1-δ_y

x_G2＝x_P2+δ_x，y_G2＝y_P2+δ_y

x_G3＝x_P3-δ_x，y_G3＝y_P3+δ_y

x_G4＝x_P4-δ_x，y_G4＝y_P4-δ_y

the side lengths of the first calculation domain rectangle G are respectively L_x1、L_y1。

Step four: determining a reference rectangle A

4.1 see fig. 7. Firstly, making two straight lines with the slopes of 1 and-1 through a central point C₁、line₂：

line₁:y＝x+(y_C-x_C)

line₂:y＝-x+(y_C+x_C)

4.2 the calculation is located in line₁Line from wind turbine generator on south and north sides₁The y-direction maximum distance (the vertical direction maximum distance in the figure). UTM coordinate (horizontal plane) of ith wind turbine generator set

Indicating that the wind turbine is located on line₁The conditions on the northwest side (upper left side in the figure) are

y_wi＞x_wi+(y_C-x_C)

In line₁Line from wind turbine generator on upper left side₁Has a maximum vertical distance of

d_LU＝max(|y_wi-[x_wi+(y_C-x_C)]|)

The wind turbine generator is positioned on line₁The conditions on the southeast side (lower right side in the figure) are

y_wi＜x_wi+(y_C-x_C)

In line₁Lower right wind turbine to line₁Has a maximum vertical distance of

d_RD＝max(|x_wi+(y_C-x_C)-y_wi|)

4.3 the calculation is located in line₂Line from wind turbine generator on south and north sides₂The y-direction maximum distance (the vertical direction maximum distance in the figure). The wind turbine generator is positioned on line₂The conditions on the northeast (upper right in the figure) are

y_wi＞-x_wi+(y_C+x_C)

In line₂Wind turbine generator on upper right side to line₂Has a maximum vertical distance of

d_RU＝max(|y_wi-[-x_wi+(y_C+x_C)]|)

The wind turbine generator is positioned on line₂The conditions on the southwest side (lower left side in the figure) are

y_wi＜-x_wi+(y_C+x_C)

In line₂Lower left wind turbine generator set to line₂Has a maximum vertical distance of

d_LD＝max(|-x_wi+(y_C+x_C)-y_wi|)

4.4 calculate the 4 border lines of the reference rectangle A.

Will be a straight line₁Translating north (upwards in the figure) by d_LUStraight line A can be obtained₃A₄：

A₃A₄：y＝x+(y_C-x_C)+d_LU

Will be a straight line₁Translating southward (downward in the figure) d_RDStraight line A can be obtained₁A₂：

A₁A₂：y＝x+(y_C-x_C)-d_RD

Will be a straight line₂Translating north (upwards in the figure) by d_RUStraight line A can be obtained₂A₃：

A₂A₃：y＝-x+(y_C+x_C)+d_RU

Will be a straight line₂Translating southward (downward in the figure) d_LDStraight line A can be obtained₄A₁：

A₄A₁：y＝-x+(y_C+x_C)-d_LD

Step five: determining a second computation domain rectangle Q corresponding to the second computation domain

5.1 the reference rectangle A is the minimum rectangular area including all wind turbines, and the actual calculation domain needs to extend a certain distance. According to a specified epitaxial distance delta_x、δ_yThe base extension distance (translation distance in the coordinate axis direction) δ of the reference rectangle a is calculated_xy：

5.2 calculate the 4 vertex-to-straight line lines of the base rectangle P, respectively₁And line₂The y-direction maximum distance (the vertical direction maximum distance in the figure).

Point P₃To line₁The maximum vertical distance of (a) is:

d_P3＝y_P3-[x_P3+(y_C-x_C)]

point P₁To line₁Has a maximum vertical distance of

d_P1＝x_P1+(y_C-x_C)-y_P1

Point P₂To line₂Has a maximum vertical distance of

d_P2＝y_P2+x_P2-(y_C+x_C)

Point P₄To line₂Has a maximum vertical distance of

d_P4＝-x_P4+(y_C+x_C)-y_P4

5.3 determining the boundary of the reference rectangle A along the coordinate axis yThe epitaxial distance is ensured not to be less than delta_xyAnd the base rectangle P is within the rectangular area after all the boundary extensions of the reference rectangle a.

Boundary line A₃A₄Distance of epitaxy: q. q.s_LU＝max(δ_xy,d_P3-d_LU)

Boundary line A₁A₂Distance of epitaxy: q. q.s_RD＝max(δ_xy,d_P1-d_RD)

Boundary line A₂A₃Distance of epitaxy: q. q.s_RU＝max(δ_xy,d_P2-d_RU)

Boundary line A₄A₁Distance of epitaxy: q. q.s_LD＝max(δ_xy,d_P4-d_LD)

5.4 referring to FIG. 7, a second computation domain rectangle Q is determined. Extending the boundary of the reference rectangle A according to the distance of 5.3 to obtain the boundary of 4 sides of the second calculation domain rectangle Q as follows:

line_1u：y＝x+(y_C-x_C)+d_LU+q_LU

line_1d：y＝x+(y_C-x_C)-d_RD-q_RD

line_2u：y＝-x+(y_C+x_C)+d_RU+q_RU

line_2d：y＝-x+(y_C+x_C)-d_LD-q_LD

the coordinates of the 4 vertices of the second computation domain rectangle Q are:

step six: determining a desired terrain data range

The read terrain data must include a first computation domain rectangle G and a second computation domain rectangle Q. See fig. 7. Selecting a rectangular area T which takes the point C as the center and has side lengths respectively parallel to the coordinate axes, wherein the side lengths of the rectangular area T are respectively L_x2And L_y2：

L_x2＝max(2(x_C-x_Q4),2(x_Q2-x_C))

＝max((d_LU+q_LU+d_LD+q_LD),(d_RD+q_RD+d_RU+q_RU))

L_y2＝max(2(y_C-y_Q1),2(y_Q3-y_C))

＝max((d_RD+q_RD+d_LD+q_LD),(d_RU+q_RU+d_LU+q_LU))

The 4 vertex coordinates of the rectangular region T are respectively:

step seven: attributes of the vertical boundaries of the computational domain are determined.

The first computation domain rectangle G and the second computation domain rectangle Q are projections of computation domain boundaries on a horizontal plane, the actual computation domain side boundaries are vertical planes, and the sides of the rectangular areas are used for referring to corresponding computation domain vertical boundary interfaces. And selecting a first calculation domain corresponding to the first calculation domain rectangle G or a second calculation domain corresponding to the second calculation domain rectangle Q as a calculation domain according to the difference of the wind direction central values of the incoming flows of the typhoon boundary layer. Both of these computation domains contain a base rectangle P, which is the region of interest for the typhoon flow field analysis.

7.1 calculating the central value of the incoming flow wind direction of the typhoon boundary layer

The typhoon boundary layer inflow condition can be from the data output of the actual measurement or the mesoscale typhoon forecasting mode of a wind measuring device at a certain point in a wind power plant area, and is represented by the wind speed and the wind direction of discrete space points distributed along the vertical height, the number of the space points is represented by M, and the first step is thatWind direction of i spatial points is alpha_i. Referring to fig. 8, the direction of the incoming wind is 0 ° or 360 ° from the north wind, 90 ° from the east wind, 180 ° from the south wind, and 270 ° from the west wind. Giving out the limit value theta of the wind direction change range of the typhoon along the vertical direction_maxTheta in engineering applications_maxIs 45 deg.. The maximum value and the minimum value of the M pieces of wind direction data are respectively as follows:

α_max＝max(α₁,α₂,…,α_i,…,α_M)

α_min＝min(α₁,α₂,…,α_i,…,α_M)

if α is_maxAnd alpha_minThe difference is 180 deg., and the typhoon boundary layer incoming flow condition is not effective. Otherwise calculating an average of wind direction maxima and minima α'_mean：

Of formula (II)'_meanThe value range is-180 degrees, and the value is converted into the range of 0-360 degrees:

α_mean＝mod(α′_mean,360)

referring to fig. 8, the following two cases are distinguished:

(1)α_max＞α_mean＞α_minthe range of wind directions does not exceed 0 ° (360 °), and for example, the maximum and minimum wind directions are 20 ° and 10 °, respectively, and the average value of the wind directions is 15 °. If for all incoming wind directions alpha_iHaving a_max＞α_i＞α_minAnd (alpha)_max-α_min)＜θ_maxThen α is_meanIs the central value of the incoming wind direction. Otherwise the typhoon boundary layer incoming flow condition is invalid.

(2)α_mean＞α_maxOr alpha_mean＜α_minIt means that when the wind direction exceeds 0 ° (360 °), for example, the maximum and minimum wind directions are 351 ° and 10 °, respectively, the average value of the wind directions is 0.5 ° (360 °)<10 degrees; the average value of wind directions when the maximum and minimum wind directions are 349 degrees and 10 degrees respectivelyIs 359.5 °>349 deg.. If for all incoming wind directions alpha_iHaving a_i＞α_maxOr alpha_i＜α_minAnd mod (α)_min-α_max,360)＜θ_maxThen α is_meanIs the central value of the incoming wind direction. Otherwise the typhoon boundary layer incoming flow condition is invalid.

For effective typhoon boundary layer inflow conditions, α_meanIs the central value of the incoming wind direction.

7.2 determining Properties of vertical boundaries of computational Domains

Referring to fig. 5 and 9, according to the range of the central value of the incoming wind direction, the first calculation domain or the second calculation domain is selected, and the corresponding boundary condition type is set.

α_meanNot less than 337.5 degree or alpha_mean< 22.5 °: selecting a second computational Domain, Q₂Q₃、Q₃Q₄As wind speed entry boundary, Q₄Q₁、Q₁Q₂Is the wind speed exit boundary;

22.5°≤α_mean< 67.5 °: selecting a first computing Domain, G₁G₂、G₂G₃As wind speed entrance boundary, G₃G₄、G₄G₁Is the wind speed exit boundary;

67.5°≤α_mean< 112.5 °: selecting a second computational Domain, Q₁Q₂、Q₂Q₃As wind speed entry boundary, Q₃Q₄、Q₄Q₁Is the wind speed exit boundary;

112.5°≤α_mean< 157.5 °: selecting a first computing Domain, G₄G₁、G₁G₂As wind speed entrance boundary, G₂G₃、G₃G₄Is the wind speed exit boundary;

157.5°≤α_mean< 202.5 °: selecting a second computational Domain, Q₄Q₁、Q₁Q₂As wind speed entry boundary, Q₂Q₃、Q₃Q₄Is the wind speed exit boundary;

202.5°≤α_mean＜247.5°: selecting a first computing Domain, G₃G₄、G₄G₁As wind speed entrance boundary, G₁G₂、G₂G₃Is the wind speed exit boundary;

247.5°≤α_mean< 292.5 °: selecting a second computational Domain, Q₃Q₄、Q₄Q₁As wind speed entry boundary, Q₁Q₂、Q₂Q₃Is the wind speed exit boundary;

292.5°≤α_mean< 337.5 °: selecting a first computing Domain, G₂G₃、G₃G₄As wind speed entrance boundary, G₄G₁、G₁G₂Is the wind speed exit boundary.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.

Claims

1. A typhoon disaster prediction method is characterized by comprising the following steps:

2. The method of predicting a typhoon disaster according to claim 1, wherein the method further comprises:

3. The method for predicting a typhoon disaster according to claim 2, wherein the boundary of the basic rectangle is extended in parallel according to a basic preset distance to obtain a first-class calculation domain rectangle;

4. A typhoon disaster prediction method according to claim 2, characterized in that the method further comprises:

5. The method according to claim 4, wherein the sector-shaped spatial regions are numbered sequentially in a clockwise direction, and the numbers are consecutive positive integers.

6. A typhoon disaster prediction method according to claim 5, wherein when the sum of the area numbers of the base terrain area and the reference terrain area is N, the number of the sector-shaped space areas is 4N, where N is a positive integer of 2 to 8.

7. The method according to claim 1 or 6, wherein when there are a plurality of computation domains, the included angles between two center lines of a computation domain rectangle projected horizontally in each computation domain and two center lines of an adjacent computation domain rectangle are 360/4N degrees, where N is a positive integer from 2 to 8.

8. The method according to claim 5, wherein a base terrain area, which is subjected to CFD simulation calculation and horizontally projected as a rectangle, is selected in the target wind farm based on the position of the target wind turbine, and 1 reference terrain area, which is horizontally projected as a rectangle, is simultaneously selected;

9. A typhoon disaster prediction apparatus, characterized by comprising:

10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 8.