Device and method for estimating far-field noise of capacitor device based on monopole array

Abstract

The invention discloses a capacitor device far-field noise estimation device and method based on a monopole array, and the method comprises the steps: carrying out the monopole sound source modeling of each capacitor unit, and arranging the monopole sound sources into a regular array in a three-dimensional space; constructing a sound pressure analytical expression of a far-field measuring point, describing the positions of the measuring point and a sound source, calculating the sound pressure of each monopole sound source at the measuring point, and carrying out accumulated calculation on the sound pressure of the whole sound source array at the measuring point; a ground reflection effect is considered, a mirror image sound source is introduced into each monopole sound source model, and a total sound pressure value at a measuring point is corrected; a directivity factor is constructed to reflect the directivity characteristics of the array, and the directivity factor and the acoustic power level of a single capacitor are used to estimate the total sound pressure level of the entire array at a specific frequency. According to the method, the sound wave coherence and the ground reflection effect are considered, and the multi-measuring-point far-field sound pressure calculation speed can be remarkably increased while the prediction precision is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power system noise prediction and control, and particularly relates to a capacitor device far-field noise estimation method using monopole sound source modeling, which is suitable for acoustic radiation modeling and engineering noise evaluation of converter stations, large-scale shunt capacitor arrays and other power devices, and is particularly suitable for application scenarios of rapid calculation of far-field plant boundary noise. BACKGROUND

[0002] Currently, far-field noise evaluation of capacitor devices mainly relies on ray tracing method and boundary element method. Specifically, the ray tracing method simulates sound ray propagation to calculate plant boundary noise by inputting capacitor device positions and sound source intensity; the boundary element method models and meshes the capacitor surface and applies boundary conditions to solve target point sound pressure values. The ray tracing method simplifies sound waves as light ray propagation model, ignores phase and interference information, has high calculation efficiency but low precision; the boundary element method considers sound wave interference effects by modeling the capacitor structure surface and applying boundary conditions, has high precision, but has large calculation amount and low efficiency when dealing with large-scale devices and far-field multiple measurement points, and is difficult to meet the engineering rapid evaluation requirements.

[0003] The information disclosed in the background section merely serves to enhance the understanding of the background of the present application, and therefore can contain information that is not prior art known to those of ordinary skill in the art. SUMMARY

[0004] The present application aims to solve the above problems and proposes a capacitor device far-field noise rapid estimation method based on monopole array modeling: first, equivalent each capacitor unit to a monopole sound source and establish an array model in three-dimensional space. Then, calculate the distance from each monopole sound source to the far-field measurement point, combine sound wave propagation theory and ground reflection effect to obtain the total sound pressure value at the far-field measurement point. Finally, adjust the total sound pressure level using the directivity factor to realize rapid estimation of far-field noise.

[0005] The object of the present application is achieved by the following technical solutions:

[0006] A capacitor device far-field noise estimation device and method based on monopole array, the device comprising:

[0007] A monopole sound source modeling module for equivalent each capacitor unit to an ideal monopole sound source and arranging into a regular array in three-dimensional space;

[0008] A sound pressure analytical expression construction module for constructing a sound pressure analytical expression at the measurement point according to the position coordinates of the monopole sound source and the measurement point position, and obtaining the sound pressure value at the measurement point;

[0009] a ground reflection correction module, configured to obtain a total sound pressure value at the measuring point according to the influence of the ground on the sound wave propagation;

[0010] a directivity factor construction module, configured to construct a directivity factor to reflect the directivity characteristics of the array, and calculate the total sound pressure level of the array in different directions according to the directivity factor.

[0011] Preferably, the sound pressure analytical expression is:

[0012]

[0013] wherein P i is the sound pressure contribution of the i th monopole sound source at Q, A is a constant, k = 2πf / c is the wave number, f is the frequency, c is the sound speed, r i is the distance from the monopole sound source to the measuring point.

[0014] Preferably, the sound pressure value P at the measuring point is:

[0015] .

[0016] Preferably, the influence of the ground on the sound wave propagation is that, considering the ground as an ideal rigid reflecting surface, there is a mirror sound source below the ground for each monopole sound source in the real sound field, which produces an additional sound pressure at the measuring point with the same phase as each monopole sound source in the real sound field.

[0017] Preferably, the sound pressure contribution P i ’ produced by the mirror sound source at the measuring point is:

[0018]

[0019] wherein r i ’ is the distance from the mirror sound source to the measuring point.

[0020] Preferably, the sound pressure value P’ of the mirror sound source at the measuring point is:

[0021] .

[0022] Preferably, the total sound pressure value p Q at the measuring point is:

[0023] .

[0024] The application also provides a monopole array-based capacitor device far-field noise estimation method, comprising the following steps:

[0025] S1: model each capacitor unit as a monopole sound source and arrange them into a regular array in a three-dimensional space;

[0026] S2: constructing an analytical expression of sound pressure of a far-field measuring point to describe the position of the measuring point, calculating the distance from each monopole sound source to the measuring point, and simplifying the distance calculation formula;

[0027] S3: considering the ground reflection effect, introducing a mirror sound source for each monopole sound source model, and correcting the total sound pressure value at the measuring point;

[0028] S4: constructing a directivity factor to reflect the directivity characteristics of the array, and using the directivity factor and the sound power level of a single capacitor to estimate the total sound pressure level of the entire array at a specific frequency.

[0029] Preferably, S1 comprises:

[0030] In a rectangular coordinate system, the monopole sound sources are arranged along the x, y and z directions according to the actual arrangement of the capacitor array to form a regular array, and the position coordinates of the i-th monopole sound source are denoted as (x i , y i , z i ).

[0031] Preferably, S2 comprises:

[0032] Suppose the position of the far-field measuring point Q is expressed in spherical coordinates as , the i-th monopole sound source (x i , y i , z i ), and the distance r i from the measuring point Q to the i-th monopole sound source is approximately expressed as:

[0033]

[0034] When the position coordinates of the field point Q are fixed, r i can be regarded as a multivariate function of (x i , y i , z i ). By using the Taylor expansion formula of the multivariate function to expand it at (0, 0, 0) and ignoring the second-order and higher-order quantities, r i can be approximated as:

[0035] .

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] Compared with the prior art, the present application does not need to perform complex geometric modeling and mesh division, has high calculation efficiency, and considers the sound wave coherence and ground reflection effect, so that the calculation speed of the far-field sound pressure of multiple measuring points can be significantly improved while ensuring the prediction accuracy, and the present application is more suitable for rapid evaluation of large-scale capacitor device plant boundary noise.

[0038] The description provided is merely an overview of the technical solution of this invention. In order to make the technical means of this invention clearer and more understandable, so that those skilled in the art can implement it according to the contents of the specification, and to make the described and other objects, features and advantages of this invention more obvious and understandable, specific embodiments of this invention are described below. Attached Figure Description

[0039] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0040] In the attached diagram:

[0041] Fig. 1 A flowchart of a far-field noise prediction method for a capacitor device based on a monopole array, provided as an embodiment of the present invention;

[0042] Fig. 2 A schematic diagram of a sound source array provided for one embodiment of the present invention.

[0043] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0044] The following will refer to the appendix. Figs. 1-2 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0045] It should be noted that some terms are used in the description and claims. Those skilled in the art should understand that the same component can be referred to by different names. The description and claims of the present application do not distinguish components by the difference in names, but by the difference in functions. As mentioned throughout the description and claims, "including" or "including" is an open term, which should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment for implementing the present application, and the description is for the purpose of the general principles of the specification, not to limit the scope of the present application. The scope of protection of the present application is defined by the appended claims.

[0046] The present application provides a monopole array-based capacitor device far-field noise estimation method, as shown in Fig. 1 , comprising the following steps:

[0047] S1: Three-dimensional monopole sound source array modeling, as shown in Fig. 2 , each capacitor unit is equivalent to an ideal monopole sound source, and the shape and sound directivity effect are ignored. In the rectangular coordinate system, according to the actual arrangement of the capacitor array, the monopole sound source is arranged along the x, y, and z directions to form a regular array, and the unit spacing is dx, dy, and dz, the first layer height is H, and the number of rows, columns, and layers of the array are n x , n y , n z , respectively. The position coordinates of the i-th monopole sound source are (x i , y i , z i ).

[0048] S2: Constructing the far-field measurement point sound pressure analytical expression. Under the condition of meeting the far-field condition (i.e. the distance between the measurement point and the sound source is far enough, so that the specific shape and size of the sound source can be ignored. The influence of sound wave propagation, thus allowing the use of a simplified mathematical model to estimate the sound pressure level. Engineering is only concerned with the factory boundary noise, the distance between the factory boundary and the unit is much larger than the unit size, and the factory boundary noise is considered to belong to the far-field sound field category), the position of the far-field measurement point Q is expressed in spherical coordinates as , the i-th monopole sound source (x i , y i , z i ), and the distance r i from the measurement point Q is approximately expressed as:

[0049] (1)

[0050] When the position coordinates of the field point Q are fixed, r i can be regarded as (x i , yi , z i ) of the multivariate function, using the Taylor expansion formula of the multivariate function to expand it at (0, 0, 0) and ignore the second and higher order quantities, then r i can be approximated as:

[0051] (2)

[0052] Due to the interference phenomenon of sound waves generated by different point sources, considering the phase information, the sound pressure contribution P i of the ith monopole sound source at Q is:

[0053] (3)

[0054] Where A is the sound pressure coefficient, the value of A is the sound pressure at the center of the sound source 1 m when r i =1, ω is the angular frequency of the sound wave, k=2πf / c is the wave number, f is the frequency, c is the sound speed, and e is the natural constant. According to the principle of sound pressure superposition, the sound pressure P of the monopole sound source above the ground at the field point Q is:

[0055] (4)

[0056] S3: Ground reflection correction and mirror sound source modeling. Considering that the ground is an ideal rigid reflecting surface, each monopole sound source (i.e. "real source") in the real sound field has a mirror sound source (i.e. "virtual source") below the ground, which produces an additional sound pressure at the measurement point Q with the same phase as the real source. If the position of the ith real source is (x i , y i , z i ), then the position of the mirror source is (x i , y i , -z i ). The distance r i ' from the mirror source to the measurement point Q is approximately expressed as:

[0057] (5)

[0058] The sound pressure contribution P i ' of the ith monopole mirror source at Q is:

[0059] (6)

[0060] Considering the ground reflection effect, the sound pressure P' contributed by the "virtual source" monopole sound source at the field point Q is:

[0061] (7)

[0062] Therefore, the total sound pressure p at Q isQ is:

[0063] (8)

[0064] S4: Directivity factor construction and fast estimation of sound pressure level. After considering the sound wave interference and ground reflection, the total sound pressure p of the capacitor device at the far-field measuring point Q is Q has been given by the superposition of real and virtual sources, and its amplitude is affected by the phase difference of each monopole, forming the directivity characteristics. Let the sound pressure generated by the monopole sound source placed at the origin at Q be p0, and define the directivity factor D of the array in the direction on the array: n is:

[0065] (9)

[0066] Further, the relationship between the total sound pressure level of the capacitor array at the field point Q and the sound pressure level of a single capacitor is:

[0067] (10)

[0068] where L W1 is the sound power level of a single capacitor at frequency f, and n is the number of capacitors. Finally:

[0069] (11)

[0070] Embodiment:

[0071] The far-field noise prediction method based on the monopole array capacitor device is used to calculate the sound field distribution of a large capacitor device. Now, the results of the 500 Hz sound pressure level data of the small capacitor device far-field sound field calculated by the boundary element method and the monopole array-based small capacitor device are compared. The sound power level of the capacitor unit at the main frequency point is shown in Table 1, and the geometric parameters of the small capacitor device to be calculated are shown in Table 2. Eight measuring points are selected in four directions and two heights around the capacitor device, which are opposite to the sleeve side and the non-sleeve side of the capacitor device. The sound pressure level is calculated, and the position coordinates of the field points are shown in Table 3. The 500 Hz sound pressure level calculation comparison results are shown in Table 4. The method proposed in the present application takes less than 0.1 s in total.

[0072] Table 1 Sound power level of capacitor unit at main frequency point

[0073]

[0074] Table 2 Geometric parameters of capacitor device to be calculated

[0075]

[0076] Table 3 Location coordinates of the field points of the small capacitor device

[0077]

[0078] Table 4 Comparison results of 500 Hz sound pressure level calculation

[0079]

[0080] Table 1 provides the sound power level data of the capacitor unit at the main frequency points, Table 2 lists the geometric parameters of the small capacitor device to be calculated, and Table 3 specifies the location coordinates of the field points. These information collectively demonstrate the noise prediction of the capacitor device of different frequencies, different sizes and layouts suitable for the application, showing its wide applicability.

[0081] As can be seen from the comparison results in Table 4, the far-field noise prediction method of the capacitor device based on the monopole array proposed in the application is generally similar to the 500 Hz sound pressure level calculation results of the boundary element method, and the large error of individual measuring points may be due to the sound directivity of the capacitor unit. The calculation error is increased by the joint action of multiple capacitor units, but it is generally within the engineering allowable error range. This means that in most cases, the application can provide sufficiently accurate results for noise evaluation in engineering practice.

[0082] In summary, by comparing the calculation results of the boundary element method and the method based on the monopole array, it can be seen that the application not only improves the calculation speed, but also ensures sufficient accuracy, and is particularly suitable for far-field noise evaluation of large-scale capacitor devices that require rapid estimation of sound pressure distribution at multiple measuring points. In addition, although there are certain simplifying assumptions, the method shows good adaptability and reliability in practical application.

[0083] The above describes the basic principles of the application in conjunction with specific embodiments, but it should be noted that the advantages, advantages, effects, etc. mentioned in the application are only examples and not limitations, and these advantages, advantages, effects, etc. cannot be considered as the application. Each embodiment must have. In addition, the above specific details are only for the purpose of example and for the purpose of understanding, and are not limited to the above specific details to implement the application.

[0084] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the application to the forms disclosed herein. Although the above has discussed a plurality of example aspects and embodiments, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations.

Claims

1. A method for predicting far-field noise of a capacitor device based on a monopole array, characterized in that, The method includes the following steps: S1: Model each capacitor unit as a monopole sound source and arrange them into a regular array in three-dimensional space; S2: Construct analytical expressions for the sound pressure levels of far-field measurement points to describe the location of the measurement points, calculate the distance from each monopole sound source to the measurement point, and simplify the distance calculation formula; S3: Considering the ground reflection effect, a mirror sound source is introduced for each monopole sound source model, and the total sound pressure value at the measurement point is corrected. S4: Construct a directivity factor to reflect the directional characteristics of the array, and use the directivity factor and the sound power level of a single capacitor to estimate the total sound pressure level of the entire array at a specific frequency.

2. The method according to claim 1, characterized in that, Preferably, S1 includes: In a Cartesian coordinate system, following the actual arrangement of the capacitor array, the monopole sound sources are arranged in a regular array along the x, y, and z directions. The position coordinates of the i-th monopole sound source are denoted as (x...). i , y i , z i ).

3. The method according to claim 1, characterized in that, S2 include: Let the position of the far-field measuring point Q be represented in spherical coordinates. The i-th monopole sound source (x i , y i , z i The distance r from the measuring point Q is... i Approximate expression: ； When the coordinates of point Q are fixed, r i It can be regarded as (x) i , y i , z i For a multivariate function , expand it at (0, 0, 0) using the Taylor expansion formula for multivariate functions and ignore second-order and higher-order quantities, then r i It can be approximated as: 。 4. A far-field noise prediction device for a capacitor device based on a monopole array, characterized in that, The device includes: The monopole sound source modeling module is used to treat each capacitor unit as an ideal monopole sound source and arrange them into a regular array in three-dimensional space. The sound pressure analytical expression construction module is used to construct the sound pressure analytical expression at the measurement point based on the position coordinates of the monopole sound source and the measurement point location, and to obtain the sound pressure value at the measurement point; The ground reflection correction module is used to obtain the total sound pressure value at the measuring point based on the influence of the ground on the propagation of sound waves. The directional factor construction module is used to construct directional factors to reflect the directional characteristics of the array and to calculate the total sound pressure level of the array in different directions.

5. The apparatus according to claim 4, characterized in that, The analytical expression for sound pressure is: ； Among them, P i Let A be the sound pressure contribution of the i-th monopole sound source at Q, where A is a constant, k = 2πf / c is the wave number, f is the frequency, c is the speed of sound, and r is the velocity of sound. i The distance is the distance from the monopole sound source to the measuring point.

6. The apparatus according to claim 5, characterized in that, The sound pressure value P at the measuring point is: 。 7. The apparatus according to claim 4, characterized in that, The influence of the ground on sound wave propagation is as follows: considering the ground as an ideal rigid reflective surface, each monopole sound source in the real sound field has a mirror sound source below the ground, which generates an additional sound pressure at the measuring point that is in phase with each monopole sound source in the real sound field.

8. The apparatus according to claim 7, characterized in that, The sound pressure contribution P generated by the mirror sound source at the measuring point i 'for: ； Where, r i ' is the distance from the mirror sound source to the measuring point.

9. The apparatus according to claim 8, characterized in that, The sound pressure value P' of the mirror sound source at the measuring point is: 。 10. The apparatus according to claim 9, characterized in that, The total sound pressure value p at the measuring point Q for: 。

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