CN109541326B - Magnetic flux leakage detection positioning method between ocean electrics - Google Patents
Magnetic flux leakage detection positioning method between ocean electrics Download PDFInfo
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Abstract
The invention discloses a novel electromagnetic leakage detection method, which comprises the following stepsThe method comprises the following steps: sampling data through an antenna; performing secondary sampling on the sampled data; constructing the subsampled data into a data vector; computing covariance to construct data vectors
Then, decomposing the covariance; obtaining different characteristic values, wherein the number of the characteristic values is the number of the signal sources; determining a signal subspace; constructing a delay matrix phi according to the sampling mode and the sampling parameters; searching two-dimensional spectrum peaks of distance and azimuth angles according to the signal parameter range by using a space spectrum estimation formula; and finding out the maximum value point, wherein the corresponding distance and angle are the position information of the electromagnetic leakage element. The new electromagnetic leakage detection principle is to change the whole system into a single matrix and a single channel completely. The method has the advantages that the problems of huge antenna matrix and interference among array elements are avoided, the complexity of calculation can be greatly simplified, the interference is effectively avoided, the magnetic flux leakage detection positioning precision is improved, and the time cost is saved.
Description
Technical Field
The invention belongs to the field of ocean engineering, and particularly relates to a method for positioning and detecting magnetic flux leakage between ocean electrics.
Background
In recent years, the production amount of offshore oil is increased year by year, the manufacturing requirements of large oil and gas modules are more and more, the harm of electromagnetic leakage can be very serious, and particularly, the influence of electromagnetic interference on an offshore platform on the control precision of the offshore platform can cause huge loss. At present, a matrix antenna method is mostly adopted for magnetic flux leakage detection between offshore electric appliances, namely, a plurality of signal acquisition antennas are installed on an ocean deck, and magnetic flux leakage signals are acquired at fixed points. The method has the advantages that the occupied area of the antenna matrix is large, the array element spacing is fixed, and the coupling problem of mutual interference exists among the array elements.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for detecting and positioning magnetic flux leakage between ocean electricity. The problems of huge antenna matrix and interference among array elements are avoided.
The invention discloses a novel electromagnetic leakage detection method, which is characterized by comprising the following steps:
step one, adopting a single-channel antenna to do uniform linear motion at a speed v outside the ocean electrical room, and installing a signal acquisition device on the single-channel antenna 1 at a time interval tausTo carry out electrical appliance in ocean electrical roomMagnetic leakage sampling;
step two, the magnetic flux leakage sampling data of the electric appliance are transmitted to the data receiving module 3, the sampling data are sorted in the data receiving module 3, and the following data matrix is constructed:
X＝φaS+N
wherein:
phi is a time delay matrix due to antenna motion;
a is a direction vector of magnetic leakage;
s is a signal vector of magnetic leakage;
n is a noisy data vector;
s(t0) Is t0Constantly leaking signals sent by electromagnetism;
m represents the number of data obtained by single batch sampling and final sampling;
k represents the number of sampling batches;
t represents the period of the leakage magnetic signal, and T is 1/f;
r represents t0The distance between the magnetic flux leakage signal source and the antenna at the moment;
f represents the leakage signal frequency;
j represents an imaginary unit;
t0representing a data acquisition start time;
r2representing the position of the first sampling point from the leakage signal source;
rMrepresenting the position of the distance from the leakage magnetic signal source at the Mth sampling point;
and step three, importing the data matrix equation into a data processing module, carrying out global spectrum peak search on the matrix equation through a space spectrum estimation algorithm to obtain a peak point of the matrix equation, and recording the distance and the angle corresponding to the maximum value point as position information of the electromagnetic leakage signal source.
The invention has the beneficial effects that: the method can effectively solve the problems that the conventional antenna matrix is large in size, the space between array elements is fixed, the coupling phenomenon exists between the array elements, the carrying is inconvenient, and the like. The new electromagnetic leakage detection principle is to change the whole system into a single matrix and a single channel completely. The problems of huge antenna matrix and interference among array elements are avoided. The complexity of calculation can be greatly simplified, interference is effectively avoided, the detection precision is improved, and the time cost is saved.
Drawings
FIG. 1 is a schematic diagram of a virtual single-channel array receiving system;
fig. 2 is a process flow diagram of the leakage flux detection system.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
The invention is based on the thought of synthetic aperture technology, replaces the traditional actual conventional matrix with the virtual matrix synthesized based on the single-channel antenna motion, and adopts single-channel receiving at the rear end, thus the whole system is completely changed into single matrix and single channel.
Fig. 1 is a schematic diagram of a virtual single-channel array receiving system, a single-channel antenna 1 performs uniform motion with a velocity v along a given direction, a signal acquisition device is installed on the single-channel antenna 1, second data sampling is performed when the single-channel antenna moves to a position 2, signal sampling is performed by analogy in sequence, sampled signals are received by a data receiving module 3 and then are sorted according to a matrix construction method, and the sampled signals are constructed into a data matrix form and transmitted to a data processing module 4 for data processing. And directly obtaining the position information of the leakage magnetic signal source from the processed data result.
The invention discloses an electromagnetic leakage detection method, which comprises the following steps:
step one, adopting a single-channel antenna to do uniform linear motion at a speed v outside the ocean electrical room, and installing a signal acquisition device on the single-channel antenna 1 at a time interval tausSampling electric appliance magnetic flux leakage in the ocean electrical room;
step two, the magnetic leakage sampling data of the electric appliance is transmitted to the data receiving module 3, the data receiving module 3 is used for sorting the sampling data to construct a data matrix,
X＝φaS+N (1)
wherein:
phi is a time delay matrix due to antenna motion;
a is a direction vector of magnetic leakage;
s is a signal vector of magnetic leakage;
n is a noisy data vector;
s(t0) Is t0Constantly leaking signals sent by electromagnetism;
m represents the number of data obtained by single batch sampling and final sampling;
k represents the number of sampling batches;
t represents the period of the leakage magnetic signal, and T is 1/f;
r represents t0The distance between the magnetic flux leakage signal source and the antenna at the moment;
f represents the leakage signal frequency;
j represents an imaginary unit;
t0representing a data acquisition start time;
r2representing the position of the first sampling point from the leakage signal source;
rMand the position of the M sampling point from the leakage magnetic signal source is represented.
The method of constructing the data matrix is described in detail below:
(a) the signal collector on the antenna 1 performs signal sampling:
let the signal sampling interval be tausLet tp＝t0+pτs(p is 0,1, 2.) then antenna tpMove to v t momentpThe received electromagnetic signal is:
x(tp)＝s(tp)+n(tp)(p＝0,1,2....)
when p is 0:
the formula is obtained by Euler transformation of a signal formula in 'signal and linear system analysis' published by advanced education publishers 1998
When p > 0:
finally obtaining the electromagnetic signal expression
In the formula: s (t)p) Is tpLeaking signals sent by electromagnetism at any time;
n(tp) Is tpInterference signals received by the time antenna;
parameter rpIs tpThe distance from the antenna to the magnetic leakage signal source at the moment;
r represents t0The distance between the magnetic flux leakage signal source and the antenna at the moment;
f represents the leakage signal frequency;
λ represents the leakage signal wavelength;
j represents an imaginary unit;
t0representing the data acquisition start time.
Then, the antenna is moved from the starting position t0The sampling data are obtained sequentially from the beginning of time
x(t0),x(t1),x(t2)...x(tk-1),x(tk),x(tk+1)...x(t(M-1)k) (3)
In the formula: t when p is 00＝t0+0τsAnd the sampling signal is denoted as x (t)0)；
When p is 1, t1＝t0+1τsAnd the sampling signal is denoted as x (t)1)；
......
T when p ═ M-1) k(M-1)k＝t0+k(M-1)τsAnd the sampling signal is denoted as x (t)(M-1)k)。
(b) The signal receiving module 3 performs secondary sampling on the acquired data:
at this time, k τ is set at time intervals TsIntercepting the sampling signal for a period, namely resampling the data in the step (3) every k times to obtain the following data;
x(t0),x(tk),x(t2k)..x(t(M-1)k). (4)
is recorded as:
x1,x2,x3...xM(5)
(c) constructing the subsampled data (5) into a data matrix;
m represents the number of data obtained by single batch sampling and final sampling;
k represents that the secondary sampling period is k times the primary sampling period;
Ndand (3) a noise signal matrix obtained by single batch sampling.
The above (a), (b) and (c) are the whole process of one-time sampling, the acquired M data finally form a one-time sampling matrix (6), in order to improve the positioning accuracy, multiple batches of sampling is needed, the steps (a), (b) and (c) are repeated, multiple batches of sampling is carried out, K batches of sampling are carried out, and K batches of sampled data form a matrix:
in the formula, the row number M represents the number of virtual matrix elements, the column number K represents the number of sampling batches, that is, the number of times of repeated sampling on the whole position, and M × K is the total number of sampling points.
(5) Constructing a time delay matrix due to antenna motion:
the K batches of sample data derived from the one-time sampling matrix of the above equation (6) can be written as:
n represents K and obtains a noise data matrix through multiple sampling;
the above formula (8) is noted as:
X＝φaS+N (1)
where X is N samples to form the final data matrix,
is the direction vector of the magnetic flux leakage,
is the signal vector of the leakage flux, N is the noise data vector,
is a time delay matrix due to antenna motion.
And step three, importing the data matrix equation (1) into the data processing module 4, carrying out global spectrum peak search on the matrix equation (1) through a spatial spectrum estimation (MUSIC) algorithm to obtain a peak point of the matrix equation (1), recording the distance and the angle corresponding to the maximum value point as position information of the electromagnetic leakage signal source, and recording the point far lower than the maximum value as noise position information searched according to the noise signal matrix N.
Example 1
In the data matrix construction method (a), the sampling time and the antenna movement distance (the antenna moves according to a specified track and acquires information, and the antenna movement distance is the track length in the practical application process) determine the virtual matrix element spacing (the sampling point position) and the virtual matrix number (the sampling point number) in the sampling process, and the longer the antenna movement distance is, the shorter the sampling period is, the smaller the sampling matrix element spacing is, and the more the sampling matrix element number is.
In the specific implementation process, in order to accurately position the specific position of the magnetic leakage in a small range, the sampling period and the sampling distance of the antenna aperture D are reasonably selected. Taking the example of selecting D equal to 1.5m, different virtual matrix element distances (sampling point positions) and virtual matrix numbers (sampling point numbers) can be selected for the leakage magnetic signals with different frequencies as shown in the following table
After the magnetic leakage signal is stable, the more the measurement and positioning array element number is, the larger the array element interval is, the higher the positioning precision is, but the cost problem is considered, the more the array element number is, the better, the verification is verified through MATLAB simulation test to obtain the upper table, and it can be known that when D is taken to be 1.5, the accurate positioning can be carried out on the 300MHz signal source in the 4.5m range, and the accurate positioning can be carried out on the 900MHz signal source in the 13.5 m range.
Therefore, for different occasions, the proper number and the proper distance of the virtual array elements can be selected according to the field size and the working frequency.
Claims (1)
1. An electromagnetic leakage detection method, characterized by comprising the steps of:
step one, adopting a single-channel antenna to do uniform linear motion at a speed V outside an ocean electrical room, and arranging a signal acquisition device on the single-channel antenna at a time interval tausSampling electric appliance magnetic flux leakage in the ocean electrical room;
step two, transmitting the electric appliance magnetic flux leakage sampling data to a data receiving module, sorting the sampling data in the data receiving module, and constructing the following data matrix:
X＝φaS+N
wherein:
phi is a time delay matrix due to antenna motion;
a is a direction vector of magnetic leakage;
s is a signal vector of magnetic leakage;
n is a noisy data vector;
s(t0) Is t0Leaking signals sent by electromagnetism at any time;
m represents the number of data obtained by single batch sampling and final sampling;
k represents the number of sampling batches;
t represents the period of the leakage magnetic signal, and T is 1/f;
r represents t0The distance between the magnetic flux leakage signal source and the antenna at the moment;
f represents the leakage signal frequency;
j represents an imaginary unit;
t0representing a data acquisition start time;
r2representing the position of the first sampling point from the leakage signal source;
rMrepresenting the position of the distance from the leakage magnetic signal source at the Mth sampling point;
and step three, importing the data matrix equation into a data processing module, carrying out global spectrum peak search on the matrix equation through a spatial spectrum estimation algorithm to obtain a peak value point of the matrix equation, and recording the distance and the angle corresponding to the maximum value point as position information of the magnetic leakage signal source.
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| CN106405253A (en) * | 2016-08-24 | 2017-02-15 | 中国气象科学研究院 | Method and apparatus for positioning object lightning radiation source |
| CN106950277A (en) * | 2017-03-29 | 2017-07-14 | 中国海洋石油总公司 | The drilling rod or Magnetic Flux Leakage Equipment for Oil Pipe Testing and detection method of a kind of marine jack rabbit formula |
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| CN106405253A (en) * | 2016-08-24 | 2017-02-15 | 中国气象科学研究院 | Method and apparatus for positioning object lightning radiation source |
| CN106950277A (en) * | 2017-03-29 | 2017-07-14 | 中国海洋石油总公司 | The drilling rod or Magnetic Flux Leakage Equipment for Oil Pipe Testing and detection method of a kind of marine jack rabbit formula |
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| 天然气集输管道腐蚀及漏磁检测方法分析;谢媚;《内蒙古石油化工》;20141231(第24期);第68-69页 * |
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