External magnetic field suppression method of DC power distribution network for ship

Abstract

The invention discloses an external magnetic field suppression method for a ship DC power distribution network, and belongs to the technical field of ship DC power distribution networks. Comprising the following steps: S1, acquiring at least two groups of straight wires with preset lengths, and calculating a magnetic field generated by the straight wires at a point N in a space with a distance of A and a total space magnetic field; s2, building an electromagnetic induction intensity calculation model suitable for the straight wire, and calculating the magnetic field induction intensity generated in the space around the N point; s3, magnetic field induction intensity generated in the space around the N point is obtained and serves as an input signal of a self-adaptive filtering algorithm, the straight wire is subjected to self-adaptive filtering to suppress external magnetic field interference, the step length is iteratively updated according to an error signal through the self-adaptive algorithm, and the external magnetic field interference is suppressed; and S4, building a current test platform, and verifying the validity of the filtered current estimation result. Magnetic field interference of a high-capacity distribution board in a ship is reduced, the electromagnetic compatibility of ship electronic equipment is improved, and stable operation of the equipment in the ship is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of direct current distribution networks for ships, and in particular relates to a method for suppressing an external magnetic field of a direct current distribution network for ships. Background Art

[0002] The medium-voltage DC integrated power system of ships adopts a medium-voltage DC grid structure, which has many advantages, such as low speed performance requirements, elimination of the mutual influence between speed and frequency, reduction of noise and vibration, and reduction of cable weight. This system has a higher power density, so it is necessary to be equipped with a high-power medium-voltage rectifier generator set, propulsion motor and large-capacity DC distribution board. These devices will generate a large amount of current when powered on, and generate a non-negligible magnetic field, which will affect the ship.

[0003] Therefore, suppressing the magnetic field generated by the large-capacity DC distribution board when it is powered on and reducing the impact on the ship's magnetic stealth has become an urgent problem to be solved. Therefore, this application proposes a method for suppressing the external magnetic field of a DC distribution network for ships. Summary of the invention

[0004] Purpose of the invention: To provide a method for suppressing the external magnetic field of a DC distribution network for ships, which solves the above-mentioned problems existing in the prior art.

[0005] Technical solution: A method for suppressing an external magnetic field of a DC distribution network for a ship, comprising the following steps:

[0006] S1. Obtain at least two groups of straight wires of predetermined lengths, calculate the magnetic field generated by the straight wires at N points in a space at a distance A through electromagnetic field theory, and superimpose the magnetic field vectors of each group of straight wires to obtain the total magnetic field in the space;

[0007] S2. Using the annular sensor array, a calculation model for the electromagnetic induction intensity of a straight conductor is constructed, and the magnetic field induction intensity generated by the space around the N points output by the straight conductor through the annular sensor is calculated by the calculation model;

[0008] S3, obtaining the magnetic field induction intensity generated in the space around point N as the input signal of the adaptive filtering algorithm, obtaining a straight wire through adaptive filtering to suppress external magnetic field interference, and iteratively updating the step size according to the error signal through the adaptive algorithm to suppress external magnetic field interference;

[0009] S4. Simulate the application scenario of DC distribution board, build a current test platform, and use the ring sensor to measure the magnetic field induction intensity. The amplification circuit on the DC distribution board forms a voltage signal proportional to the DC current. Adaptive filtering is used to suppress external magnetic field interference. The step size is iteratively updated according to the error signal through an adaptive algorithm to suppress external magnetic field interference. At the same time, a DC current clamp is used for comparison to verify the validity of the filtered current estimation result.

[0010] Preferably, in step S1, according to the busbar shape rule in the switchboard and the distribution of current density in the busbar, the spatial magnetic field at point N is calculated by formula (1), and the total spatial magnetic field can be obtained by vector superposition, wherein formula (1) is as follows:

[0011]

[0012] In the formula: W represents the width of the straight wire, T represents the thickness of the straight wire, l represents the length of the straight wire, x N Indicates the x-axis position of point N, y N Indicates the y-axis position of point N.

[0013] Preferably, the calculation formula for building a calculation model for the electromagnetic induction intensity of a straight wire is as follows:

[0014]

[0015] In the formula: μ0 is the vacuum magnetic permeability, L is the distance between the annular sensor and the center of the straight wire, t is the current measurement time, θ is the offset angle of the line connecting the annular sensor array and the center of the straight wire, λ is the ratio of the straight wire spacing to the radius of the annular sensor array, and I is the straight wire current. The magnetic induction intensity at the annular sensor at the corresponding position of the straight wire is calculated by formula (2).

[0016] Preferably, in step S3, the calculation process of the adaptive filtering algorithm is as follows:

[0017] Get the electromagnetic induction intensity B N As the input signal, it is substituted into formula (3) to calculate the average signal B avg (t), using the calculated average signal B avg (t), the step size parameter μ is calculated by formula (4);

[0018] Get the current weight w i (t), combined with the step size parameter μ and the historical value B of the Sudoku signal N (Ti) is substituted into formula (5) to obtain the updated weight w i (t+1);

[0019] The updated weight w is calculated i Substitute (t+1) into formula (6) to calculate the output signal B ref (t), the calculated average signal B avg (t) minus the calculated output signal B ref (t), we can get the error signal e(t), which is obtained by input signal and average signal B avg (t) and weight w i(t) to iteratively update the weights to minimize the error signal e(t) and complete the adaptive filtering of the signal;

[0020]

[0021] w i (t+1)=w i (t)+2μe(t)B N (ti) (5)

[0022]

[0023] Where: i represents the counter for accessing the weight coefficient corresponding to each time delay.

[0024] Preferably, in the adaptive filtering process, the offset angle of the annular sensor array is adjusted to determine the influence of the ratio λ of the straight wire spacing to the annular sensor array radius on the measurement of the magnetic induction intensity generated by the straight wire, and the process is as follows:

[0025] By setting the offset angle of the annular sensor array and changing the array radius, the relative error between the output result after filtering and the target magnetic induction intensity is obtained by obtaining the ratio λ of the straight wire spacing to the annular sensor array radius, and the influence of the distance between the annular sensor array and the interference source on the relative error is determined as follows:

[0026] Before filtering:

[0027] When the value of λ increases, the distance between the annular sensor array and the interference source is farther, and the relative error is larger. Conversely, the distance between the annular sensor array and the interference source is closer, and the relative error is smaller.

[0028] After filtering:

[0029] When the value of λ is greater than 3, the relative error of the magnetic induction intensity is less than 0.2%. The greater the current to be measured, the smaller the relative error.

[0030] Preferably, in the adaptive filtering process, the influence of the change of the initial angle of the sensor array on the measurement of the magnetic induction intensity generated by the straight wire is determined by adjusting the offset angle θ between the annular sensor array and the center line of the straight wire, and the process is as follows:

[0031] The offset angle θ is set to an offset range of 0°-90°, and the range of the current to be measured and the interference current is preset to 60-300A. By obtaining the straight wire thickness T and the straight wire length l, the influence of the change of the offset angle θ on the relative error is determined as follows:

[0032] Before filtering:

[0033] When the offset angle θ is 30°-90°, the relative error changes with the offset angle θ;

[0034] After filtering:

[0035] When the offset angle θ varies between 0° and 90°, the relative error is not affected by the offset angle θ.

[0036] Preferably, the validity verification process of the filtered current estimation result is as follows:

[0037] Obtain two groups of straight wires and connect them to a current generator at the same time. One group of straight wires is placed vertically in a ring sensor array, and the other group of straight wires is placed vertically in a DC current clamp. The ring sensor array cooperates with an adaptive filtering algorithm to determine the validity of the current estimation result after filtering by adjusting the relative error between the current value before current testing filtering and the given value and the relative error between the current value after filtering and the given value.

[0038] Adjust the output current of the current generator so that the current amplitude of the two sets of straight wires ranges from 50 to 300A;

[0039] Before filtering:

[0040] The current value directly output by the ring sensor array contains ripple noise and has a large relative error;

[0041] After filtering:

[0042] The ripple noise contained in the current value directly output by the annular sensor array is removed, and the relative error is reduced.

[0043] Beneficial effects: The present invention relates to a method for suppressing an external magnetic field of a DC distribution network for ships. The method uses a ring sensor array in conjunction with an adaptive filtering algorithm to filter straight conductors, thereby suppressing the magnetic field generated by a large-capacity DC distribution board in a ship when powered on, reducing the impact on the ship's magnetic stealth, thereby reducing the occurrence of mine magnetic fuse action. Secondly, the magnetic field interference of the large-capacity distribution board in the ship is reduced, the electromagnetic compatibility of the ship's electronic equipment is improved, and the stable operation of various equipment in the ship is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a system block diagram of the present invention;

[0045] Figure 2 is a schematic diagram of an annular sensor array of the present invention;

[0046] Figure 3 is a curve diagram showing the change of relative error with offset angle of the present invention;

[0047] Figure 4The graph is a variation curve of the relative error of the present invention with the ratio of the straight wire spacing to the annular sensor array radius. DETAILED DESCRIPTION

[0048] like Figures 1 to 4 As shown, the present invention provides a technical solution: a method for suppressing an external magnetic field of a DC distribution network for a ship, comprising the following steps:

[0049] S1. According to the busbar shape rule in the distribution board and the distribution of current density in the busbar, obtain at least two groups of straight wires of predetermined lengths, and calculate the magnetic field generated by the straight wires at N points in a space with a distance A through electromagnetic field theory. The calculation process of the magnetic field generated by the straight wires at N points in a space with a distance A is as follows:

[0050] The spatial magnetic field at point N is calculated by formula (1), which is as follows:

[0051]

[0052] In the formula: W represents the width of the straight wire, T represents the thickness of the straight wire, l represents the length of the straight wire, x N Indicates the x-axis position of point N, y N It represents the y-axis position of point N, and the magnetic field vectors of each group of straight wires are superimposed to obtain the total magnetic field in space.

[0053] S2. Using the annular sensor array, a calculation model for the electromagnetic induction intensity of a straight conductor is constructed. The calculation model is used to calculate the magnetic field induction intensity generated by the space around the N points output by the straight conductor through the annular sensor. The calculation formula for the calculation model for the electromagnetic induction intensity of a straight conductor is as follows:

[0054]

[0055] In the formula: μ0 is the vacuum magnetic permeability, L is the distance between the annular sensor and the center of the straight wire, t is the current measurement time, θ is the offset angle of the line connecting the annular sensor array and the center of the straight wire, λ is the ratio of the straight wire spacing to the radius of the annular sensor array, and I is the straight wire current. The magnetic induction intensity at the annular sensor at the corresponding position of the straight wire is calculated by formula (2);

[0056] In this embodiment, the annular sensor array used is as follows: Figure 2 As shown, B in the figure 11 , B 12 , B 13 , B 14 They represent the magnetic induction intensity generated by the four elements on the first group of straight wires, B 21 , B 22 , B 23 , B 24They represent the magnetic induction intensity generated by the four elements on the second group of straight wires respectively. Substituting them into formula (2) can obtain the superposition of the magnetic vectors generated by the current to be measured and the interference current corresponding to the electromagnetic induction intensity at the annular sensor, that is, the magnetic induction intensity at the annular sensor.

[0057] S3. Obtain the magnetic field induction intensity generated in the space around point N calculated in step S2 as the input signal of the adaptive filtering algorithm, obtain the straight conductor through adaptive filtering to suppress external magnetic field interference, iteratively update the step size according to the error signal through the adaptive algorithm, suppress external magnetic field interference, use the annular sensor array in conjunction with the adaptive filtering algorithm to filter the straight conductor, suppress the magnetic field generated by the large-capacity DC distribution board in the ship when powered on, reduce the impact on the ship's magnetic stealth, thereby reducing the occurrence of mine magnetic fuse action, secondly, simultaneously reduce the magnetic field interference of the large-capacity distribution board in the ship, improve the electromagnetic compatibility of the ship's electronic equipment, and ensure the stable operation of various equipment in the ship, wherein the calculation process of the adaptive filtering algorithm is as follows:

[0058] Get the electromagnetic induction intensity B N As the input signal, it is substituted into formula (3) to calculate the average signal B avg (t), using the calculated average signal B avg (t), the step size parameter μ is calculated by formula (4);

[0059] Get the current weight w i (t), combined with the step size parameter μ and the historical value B of the Sudoku signal N (Ti) is substituted into formula (5) to obtain the updated weight w i (t+1);

[0060] The updated weight w is calculated i Substitute (t+1) into formula (6) to calculate the output signal B ref (t), the calculated average signal B avg (t) minus the calculated output signal B ref (t), we can get the error signal e(t), which is obtained by input signal and average signal B avg (t) and weight w i (t) to iteratively update the weights to minimize the error signal e(t) and complete the adaptive filtering of the signal;

[0061]

[0062] w i (t+1)=w i (t)+2μe(t)B N (ti) (5)

[0063]

[0064] Where: i represents the counter for accessing the weight coefficient corresponding to each time delay.

[0065] In a further embodiment, during the adaptive filtering process, the offset angle of the annular sensor array is adjusted to determine the influence of the ratio λ of the straight wire spacing to the annular sensor array radius on the measurement of the magnetic induction intensity generated by the straight wire, and the process is as follows:

[0066] like Figure 3 As shown, by setting the offset angle of the annular sensor array, changing the array radius, obtaining the change in the ratio λ of the straight wire spacing to the annular sensor array radius on the relative error between the output result after filtering and the target magnetic induction intensity, judging the size of the ratio λ of the straight wire spacing to the annular sensor array radius, judging the influence of the distance between the annular sensor array and the interference source on the relative error, the judgment is as follows:

[0067] Before filtering:

[0068] When the value of λ increases, the distance between the annular sensor array and the interference source is farther, and the relative error is larger. Conversely, the distance between the annular sensor array and the interference source is closer, and the relative error is smaller.

[0069] After filtering:

[0070] When the value of λ is greater than 3, the relative error of the magnetic induction intensity is less than 0.2%. The greater the current to be measured, the smaller the relative error.

[0071] In the adaptive filtering process, the offset angle θ between the annular sensor array and the center line of the straight conductor is adjusted to determine the effect of the change in the initial angle of the sensor array on the measurement of the magnetic induction intensity generated by the straight conductor. The process is as follows:

[0072] like Figure 4 As shown, the offset range of the offset angle θ is set to 0°-90°, the range of the current to be measured and the interference current is preset to 60-300A, and the influence of the change of the offset angle θ on the relative error is determined by obtaining the straight wire thickness T and the straight wire length l. The determination is as follows:

[0073] Before filtering:

[0074] When the offset angle θ is 30°-90°, the relative error changes with the offset angle θ;

[0075] After filtering:

[0076] When the offset angle θ varies between 0° and 90°, the relative error is not affected by the offset angle θ.

[0077] S4. Simulate the application scenario of DC distribution board, build a current test platform, and use the ring sensor to measure the magnetic field induction intensity. The voltage signal proportional to the DC current is formed through the acquisition and amplification circuit on the DC distribution board. Adaptive filtering suppresses external magnetic field interference. The step size is iteratively updated according to the error signal through the adaptive algorithm to suppress external magnetic field interference. At the same time, a DC current clamp is used as a comparison to verify the validity of the current estimation result after filtering. The validity verification process of the current estimation result after filtering is as follows:

[0078] Obtain two groups of straight wires and connect them to a current generator at the same time. One group of straight wires is placed vertically in a ring sensor array, and the other group of straight wires is placed vertically in a DC current clamp. The ring sensor array cooperates with an adaptive filtering algorithm to determine the validity of the current estimation result after filtering by adjusting the relative error between the current value before current testing filtering and the given value and the relative error between the current value after filtering and the given value.

[0079] Adjust the output current of the current generator so that the current amplitude of the two sets of straight wires ranges from 50 to 300A;

[0080] Before filtering:

[0081] The current value directly output by the ring sensor array contains ripple noise and has a large relative error;

[0082] After filtering:

[0083] The ripple noise contained in the current value directly output by the annular sensor array is removed, and the relative error is reduced.

[0084] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A method for suppressing an external magnetic field of a DC distribution network for a ship, characterized in that: The following steps are involved: S1. Obtain at least two groups of straight wires of predetermined lengths, calculate the magnetic field generated by the straight wires at N points in a space at a distance A through electromagnetic field theory, and superimpose the magnetic field vectors of each group of straight wires to obtain the total magnetic field in the space; S2. Using the annular sensor array, a calculation model for the electromagnetic induction intensity of a straight conductor is constructed, and the magnetic field induction intensity generated by the space around the N points output by the straight conductor through the annular sensor is calculated by the calculation model; S3, obtaining the magnetic field induction intensity generated in the space around point N as the input signal of the adaptive filtering algorithm, obtaining the straight wire through adaptive filtering to suppress the external magnetic field interference, and iteratively updating the step size according to the error signal through the adaptive algorithm to suppress the external magnetic field interference of the DC switchboard in the ship; S4. Simulate the application scenario of DC distribution board, build a current test platform, and use the ring sensor to measure the magnetic field induction intensity. The amplification circuit on the DC distribution board forms a voltage signal proportional to the DC current. Adaptive filtering is used to suppress external magnetic field interference. The step size is iteratively updated according to the error signal through an adaptive algorithm to suppress external magnetic field interference. At the same time, a DC current clamp is used for comparison to verify the validity of the filtered current estimation result.

2. The method for suppressing external magnetic field of a DC distribution network for a ship according to claim 1, characterized in that: In step S1, according to the busbar shape rule in the switchboard and the distribution of current density in the busbar, the spatial magnetic field at point N is calculated by formula (1), and the total spatial magnetic field can be obtained by vector superposition, where formula (1) is as follows: In the formula: W represents the width of the straight wire, T represents the thickness of the straight wire, l represents the length of the straight wire, x N Indicates the x-axis position of point N, y N Indicates the y-axis position of point N.

3. The method for suppressing external magnetic field of a DC distribution network for a ship according to claim 1, characterized in that: The calculation formula for building a calculation model for the electromagnetic induction intensity of a straight wire is as follows: In the formula: μ0 is the vacuum magnetic permeability, L is the distance between the annular sensor and the center of the straight wire, t is the current measurement time, θ is the offset angle of the line connecting the annular sensor array and the center of the straight wire, λ is the ratio of the straight wire spacing to the radius of the annular sensor array, and I is the straight wire current. The magnetic induction intensity at the annular sensor at the corresponding position of the straight wire is calculated by formula (2).

4. The method for suppressing external magnetic field of a DC distribution network for a ship according to claim 1, characterized in that: In step S3, the calculation process of the adaptive filtering algorithm is as follows: Get the electromagnetic induction intensity B N As the input signal, it is substituted into formula (3) to calculate the average signal B avg (t), using the calculated average signal B avg (t), the step size parameter μ is calculated by formula (4); Get the current weight w i (t), combined with the step size parameter μ and the historical value B of the Sudoku signal N (Ti) is substituted into formula (5) to obtain the updated weight w i (t+1); The updated weight w is calculated i Substitute (t+1) into formula (6) to calculate the output signal B ref (t), the calculated average signal B avg (t) minus the calculated output signal B ref (t), we can get the error signal e(t), which is obtained by input signal and average signal B avg (t) and weight w i (t) to iteratively update the weights to minimize the error signal e(t) and complete the adaptive filtering of the signal; w i (t+1)=w i (t)+2μe(t)B N (t-i) (5) Where: i represents the counter for accessing the weight coefficient corresponding to each time delay.

5. The method for suppressing external magnetic field of a DC distribution network for a ship according to claim 4, characterized in that: In the adaptive filtering process, the offset angle of the annular sensor array is adjusted to determine the influence of the ratio λ of the straight wire spacing to the annular sensor array radius on the measurement of the magnetic induction intensity generated by the straight wire. The process is as follows: By setting the offset angle of the annular sensor array and changing the array radius, the relative error between the output result after filtering and the target magnetic induction intensity is obtained by obtaining the ratio λ of the straight wire spacing to the annular sensor array radius, and the influence of the distance between the annular sensor array and the interference source on the relative error is determined as follows: Before filtering: When the value of λ increases, the distance between the annular sensor array and the interference source is farther, and the relative error is larger. Conversely, the distance between the annular sensor array and the interference source is closer, and the relative error is smaller. After filtering: When the value of λ is greater than 3, the relative error of the magnetic induction intensity is less than 0.2%. The greater the current to be measured, the smaller the relative error.

6. The method for suppressing external magnetic field of a DC distribution network for a ship according to claim 4, characterized in that: In the adaptive filtering process, the offset angle θ between the annular sensor array and the center line of the straight conductor is adjusted to determine the effect of the change in the initial angle of the sensor array on the measurement of the magnetic induction intensity generated by the straight conductor. The process is as follows: The offset angle θ is set to an offset range of 0°-90°, and the range of the current to be measured and the interference current is preset to 60-300A. By obtaining the straight wire thickness T and the straight wire length l, the influence of the change of the offset angle θ on the relative error is determined as follows: Before filtering: When the offset angle θ is 30°-90°, the relative error changes with the offset angle θ; After filtering: When the offset angle θ varies between 0° and 90°, the relative error is not affected by the offset angle θ.

7. The method for suppressing external magnetic field of a DC distribution network for a ship according to claim 1, characterized in that: The validation process of the filtered current estimation result is as follows: Obtain two groups of straight wires and connect them to a current generator at the same time. One group of straight wires is placed vertically in a ring sensor array, and the other group of straight wires is placed vertically in a DC current clamp. The ring sensor array cooperates with an adaptive filtering algorithm to determine the validity of the current estimation result after filtering by adjusting the relative error between the current value before current testing filtering and the given value and the relative error between the current value after filtering and the given value. Adjust the output current of the current generator so that the current amplitude of the two sets of straight wires ranges from 50 to 300A; Before filtering: The current value directly output by the ring sensor array contains ripple noise and has a large relative error; After filtering: The ripple noise contained in the current value directly output by the annular sensor array is removed, and the relative error is reduced.

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