Method and apparatus for measuring the buried depth of a line
阅读说明：本技术 用于测量线的埋藏深度的方法及设备 (Method and apparatus for measuring the buried depth of a line ) 是由 柯贝尔·简 于 2018-06-14 设计创作，主要内容包括：本发明涉及一种用于测量越来越多地铺设在陆地上和水中的土壤表面下的线的埋藏深度的方法和设备。为了提高测量精度,使用一个以上在xy平面上延伸的励磁线圈或传输线圈,传输线圈在基本上垂直于线的中心轴延伸的跨度中彼此相邻放置并且在沿着该中心轴的线上移动；传输线圈以时滞方式传输电磁脉冲作为初级信号,并且使用接收线圈,这些接收线圈分布在xy平面上的传输线圈阵列上,并在彼此正交延伸的至少两个轴上测量；并且所有接收线圈都响应于传输线圈传输的初级脉冲来测量次级信号。(The present invention relates to a method and an apparatus for measuring the burial depth of lines under the surface of soils increasingly laid on land and in water. In order to improve the measurement accuracy, more than one excitation coil or transmission coil extending in the xy-plane is used, the transmission coils being placed adjacent to each other in a span extending substantially perpendicular to the central axis of the line and being moved on the line along this central axis; the transmission coil transmits electromagnetic pulses as primary signals in a time-lapse manner, and uses reception coils which are distributed on the transmission coil array on the xy plane and measured on at least two axes extending orthogonally to each other; and all receiving coils measure the secondary signal in response to the primary pulse transmitted by the transmitting coil.)
1. A method for measuring the burial depth (Delta) of a buried line (2),
wherein the detector unit (1) transmits an electromagnetic pulse (B, B ', B') as a primary signal and receives a secondary signal (B) r) And calculating the distance (D) of the detector unit (1) from the line (2) on the basis of the secondary signal, and
while measuring the height (d) of the detector unit (1) above the soil surface (BO),
and for determining the thickness (a) of the covering, calculating the difference between the distance (D) and the height (D), characterized in that,
using one or more excitation or transmission coils (3, 3') extending in the xy-plane,
the transmission coils (3, 3') are positioned adjacent to each other in a span extending substantially perpendicular to the central axis (M) of the line (2), and
moving substantially along the central axis (M) on a line (2);
the transmission coil (3, 3 ') transmits a time-delayed electromagnetic pulse (B, B ', B ') as a corresponding primary signal, and
using receiving coils (4) which are arranged in an evenly distributed manner on an array of transmission coils (3, 3') in an xy-plane and which are measured on at least two axes (x, z) oriented orthogonally to one another; and is
All receiving coils (4) measure secondary signals (B) in response to the transmission of the respective primary pulses (B, B ', B ") by the transmitting coils (3, 3', 3 ″) r)。
2. Method according to the preceding claim, characterized in that the receiving coil (4) measures the secondary signal (B) over a certain time range only after a fixed time lag (Δ t) with respect to the transmission of the electromagnetic pulse (B, B ', B ") by the transmitting coil (3, 3') r)。
3. Method according to the preceding claim, characterized in that a time lag (Δ t) in the range of 400 to 550 μ s and preferably about 498 μ s is used.
4. Method according to any of the preceding claims, characterized in that the secondary signal (B) is carried out for a time range up to about 10ms r) The measurement of (2).
5. Method according to any of the preceding claims, characterized in that receiving coils (4) are used which are placed in an evenly distributed manner, which receiving coils all lie within the array consisting of transmission coils (3, 3', 3 ") or in a plane parallel to the array.
6. An apparatus for measuring the thickness (Δ) of a covering of a wire (2), the apparatus comprising:
a detector unit (1) which is designed to transmit an electromagnetic pulse as a primary signal and to receive a secondary signal (B) r) (ii) a And
evaluation means for determining the distance (D) of the detector unit (1) from the line (2);
means for determining the height (D) of the detector unit (1) above the soil surface (BO); and
means for determining the thickness (Delta) of the covering by calculating the difference between the distance (D) of the detector unit (1) from the line (2) and the height (D) of the detector unit (1) above the soil surface (BO),
it is characterized in that the preparation method is characterized in that,
as means for transmitting the primary signal, more than one excitation or transmission coil (3, 3') extending in the xy-plane is provided,
the transmission coils (3, 3') are arranged adjacent to each other in a span extending substantially perpendicular to a central axis (M) of the line (2) and are movable on the line (2) substantially along the central axis (M);
the transmission coil (3, 3 ') is configured to transmit an electromagnetic pulse as a primary signal (B, B ', B ') in a time-lapse manner, and
receiving coils (4) are used, which are arranged in an evenly distributed manner in the xy-plane on the array of transmission coils (3) and which measure on at least two mutually orthogonal axes (x, z); and
all receiving coils (4) are configured to measure respective secondary signals (B) in response to transmission of respective primary pulses (B, B ', B ") by the transmitting coils (3, 3', 3 ″) r)。
7. Device according to the preceding claim, characterized in that a pair of receiving coils (4) of different axes (x, z) is combined into a receiver unit (5), wherein the receiver unit (5) is constructed inside an array of transmitting coils (3, 3', 3 ") or inside a plane parallel to said array.
8. Device according to any of the preceding claims, characterized in that the receiver unit (5) is located in the xy-plane parallel to the array consisting of transmission coils (3, 3', 3 ").
9. Device according to any of the three preceding claims, characterized in that the transmission coil (3, 3', 3 ") and the receiver unit (5) are fixed to a wing-shaped support consisting of a non-conductive material.
10. Device according to any of the four preceding claims, characterized in that each transmission coil (3, 3', 3 ") is constructed as a rectangle with side lengths of about 1.5m by about 1.41m, with windings at a nominal current of about 170A.
Technical Field
The invention relates to a method and a device for measuring the burial depth of lines of the type in question, which are increasingly laid under the surface of soil on land and in water in the form of pipes and pipelines and energy supply cables and/or data cables.
Background
In order to protect such a wire from external mechanical influences, but also from drastic fluctuations in temperature, and thus to obtain as stable a maintenance as possible of the intrinsic temperature, a wire of the type described above is laid in the ground below the soil surface. In this case, a certain depth below the soil surface is specified, which depth is usually referred to as the burial depth in the case of a wire, which is usually placed in a slit-shaped trench.
On land, there is a need to make sufficient identification of such lines and possibly to additionally place protective structures on the respective lines in order to prevent damage or excavation of buried depths to the greatest extent, for example in earth working. DE19614707a1 also suggests applying corresponding warning signals in the form of electromagnetic waves to these cables, so that when a receiver approaches a cable, a corresponding warning can be received.
Other problems arise when using buried underground lines of the type described above in a body of water, and particularly below the seabed. For identification, the path of the line may actually be included in the chart. Furthermore, additional protection may be provided for sections of the line's path that are particularly threatened by traffic or icebergs. In order to protect them from mechanical damage of the kind that may be caused, for example, by anchors, lines, for example in the form of submarine cables, are laid at a certain minimum depth below the seabed. However, tides and currents can reduce this depth to the point where the line is uncovered. As a result, this type of covering may therefore prove to be inadequate, particularly for large anchors.
However, the covering of the line, which is usually composed of sand and/or gravel, will be moved and changed by the motion of the waves and the tides and/or currents in the adjacent water layers. Thus, the seabed is not static. Due to tides and currents, the seabed continues to move, especially near the estuary. As a result, it is possible to fall below even the specified minimum burial depth of the line in a short time. The line may also be swept completely uncovered and/or change its position by the above-mentioned exemplary effect.
Thus, a covering layer, for example a covering layer extending from an offshore wind farm to a gathering point on shore as a covering for a so-called export cable or transmission cable and usually protected with a thickness or layer thickness of about 3m, can be completely swept away from the covering in the course of several months due to the influence of the tidal current. At least a portion of the wire is then directly exposed to the mechanical forces of the water. But the different dissipation of temperature differences and self-heating in the water along the long grooves can lead to regionally different elongation and compression of the wire, resulting in displacement or even bending of the wire in any direction in space. For many wires it is very important that the temperature is as uniform as possible due to sufficient burial depth, especially in the case of high voltage cables, since they are very sensitive to thermal overload. Excessive thermal loads occurring in certain areas can cause undesirable ageing effects, particularly in insulation, but also in connection bushings and the like, and can thus lead to a shortened service life, to premature failure, and can thus reduce the availability of the network. Also, this heating phenomenon places separate capacity limitations on the affected wires in addition to changing environmental conditions.
As part of a gathering, especially of an offshore system, it is necessary to be able to provide evidence that all lines are correspondingly adequately covered.
In addition, it is necessary to perform an annual check of the buried depth of the respective lines. For this purpose, there are known methods, in particular one in DE2530598a1, in which, on the one hand, the distance between the measuring point and the pipe composed of magnetic material must first be determined, and then, by means of an electromagnetic alternating current method, the secondary magnetic field signal injected into the pipe is measured in the detector unit to determine the distance, and, on the other hand, sonar measurement is used as a basis for determining the distance between the detector units and the corresponding surface of the seabed as the surface of the covering. This makes it possible to determine the thickness of the cover layer on the basis of a simple difference measurement.
Further, GB2419956B discloses a method of detecting submarine cables and other electrical conductors on the seabed or under the ocean using pulsed electromagnetic fields.
Disclosure of Invention
The object of the invention is to modify the method and the corresponding device by improving the measurement accuracy.
According to the invention, this is achieved by the features of the independent claims, wherein a method for measuring the buried depth of a line, in which method a detector unit sends electromagnetic pulses as a primary signal and receives a secondary signal and at the same time measures the height of the detector unit above the bottom, is characterized in that more than one excitation coil extending in the xy-plane is used, which excitation coils are placed next to each other in a direction substantially perpendicular to the central axis of the line, along which central axis is parallel to the y-axis of a cartesian coordinate system, and are moved substantially on the line. The exciter coil transmits electromagnetic pulses as primary signals in a time-lapse manner. This results in a transport rod which is moved in a substantially vertically aligned direction over the line to be investigated. In addition, the receiving coils are evenly distributed in the transmission coil array in the xy-plane and the receiving coils measure on at least two axes of said cartesian coordinate system, the x-and z-axes, orthogonal to each other and to the elongation of the line and to the propagation direction. All such transmission coils measure the secondary signal in response to the transmission of the primary pulse by the transmission coil. Thus, in an arrangement of transmission coils, an array of receiving coils is used to pick up secondary signals from different respective locations. Due to the spatial arrangement of the magnetic field, the receiving coils arranged in a distributed manner in the xy plane detect a secondary signal which may always have spatial components of different magnitudes. A better inference can be made about the depth position of the line to be investigated. Since the distance determination of the height above the sea bed is now very accurate, for example from sonar measurements, the thickness of the covering of the line can be determined very reliably based on the distance between the line and the detector unit (on the one hand) and on the difference between the height of the detector unit above the sea bed (on the other hand).
The object is also achieved by a device comprising an array of more than one excitation coil extending in the xy-plane. An excitation coil extending substantially perpendicular to the central axis of the wire is arranged to move substantially along this central axis of the wire. The coil is configured to transmit a time-lapse electromagnetic pulse; and are distributed uniformly over the array of transmission coils in at least two pairs of receiving coils, the measurements being performed on at least two axes orthogonal to each other, respectively, all of the transmission coils being configured to perform measurements of the secondary signal in response to transmission of the primary pulse by the transmission coils. As long as two receiving coils are used in pairs, the respective two axes are orthogonal to the central axis of the line and the propagation direction.
Advantageous modifications are the subject matter of the respective independent claims. According to them, for example, in the case of evaluation, the receiving coil measures the secondary signal as a reaction to the primary pulse only after a fixed time lag with respect to the transmission of the electromagnetic pulse or the primary pulse by the transmission coil within a certain time period. The time lag between the transmission of the primary pulse and the measurement of the secondary signal is, for example, in the range of 400 to 550 μ s (microseconds), and is preferably approximately 498 μ s for use in seawater or salt water, the time range during the measurement span varying depending on different variables, such as line diameter, line depth, water conductivity, respectively.
In an embodiment of the present invention, it is preferred that the measurement of the secondary signal is performed in a time range of up to about 10ms (milliseconds). In an embodiment of the invention, the signal has disappeared after 10ms, and this is why the measurement has stopped, resulting in the time range being empirical. However, there are situations that are conceivable, for example, where the cable is heavier and thicker or where the cable is buried at a lower depth, the signal will disappear after more than 10ms (for example, after 15 ms). In this case, it is desirable to continue the measurement until all relevant signals have disappeared, thereby increasing the time range to about 15 ms.
For evaluation, the time frame of the start was omitted to eliminate the effect of many side effects, such as reflections caused by sea water or salt water, etc. In an alternative method, the correction for the influence of brine is made by first measuring the secondary signal obtained only from the brine and then subtracting it from the secondary signal received during the burial depth of the analysis line. The result of this is exactly the secondary signal from the line.
In one embodiment, the arrangement or pair of receiving coils is preferably provided as a receiver unit, which is constructed like a small cube in an array of transmitting coils or a plane parallel to the array. However, in an alternative embodiment, the receiver unit is located in the xy-plane parallel to the array of transmission coils. However, in view of the effective size of the receiver elements in real life, it will of course be appreciated by those skilled in the art that even a somewhat staggered position of the receiver elements is considered to be the position of the receiver elements in the xy-plane.
Preferably, the transmission coil and the receiver or receiver unit are fixed to a wing-shaped support made of a non-conductive material. Such a design can be implemented in a flow-optimized manner so as to be positionally stable with reasonable flow resistance also at nominal speeds of the device under water as described above. The detector unit constructed in this way can also be changed in its position, in particular with respect to the line, by means of a control device using known means and methods. In addition to controllable rudders, small screws driven by electric or compressed air motors may be used, as is known for small submarines or remotely operated underwater vehicles (ROVs).
Drawings
Further features and advantages of embodiments according to the invention will be described in more detail below in connection with exemplary embodiments on the basis of the figures. In the drawings:
FIG. 1 is a schematic top view of an apparatus moving centrally at a velocity v on a line extending below the seabed surface to measure the thickness of a covering;
fig. 2a and 2b show schematic views of a section extending in plane II-II of fig. 1 during impingement of an electromagnetic pulse and during transmission of a secondary signal.
Detailed Description
Like reference numerals are used for like elements throughout the drawings. Furthermore, a cartesian coordinate system is used in all figures to model the ideal application situation, wherein the central axis of the lines and the direction of movement of the device according to the invention are parallel to the y-axis of said cartesian coordinate system.
As the importance of so-called off-shore wind farms for the production of renewable energy sources is increasing, it is very important to protect, monitor and/or inspect the wire networks to be built and maintained for these wind farms. Without limiting the field of use of the invention, only the examination of such lines is discussed below. Basically, relevant and alternative fields of use in the archaeological field, the field of exploration of natural resources or the field of locating pipelines, etc., are not excluded from the use of the method and device according to the invention.
The diagram in fig. 1 shows a top view of a device 1 which is moved centrally as a detector unit at a velocity v on a line 2 extending below the seabed surface BO to measure the thickness Δ of the covering. In this case, the device 1 comprises three excitation or
As shown in more detail in fig. 2a and 2B, the transmission coils 3, 3 ', 3 "transmit electromagnetic pulses B, B', B" that are time-shifted with respect to each other as primary signals. These pulses B, B', B "also penetrate the indicated sea bed surface BO of the sea bed and excite a flow of induced current in the conductive material of the extended wire 2. These currents decay and in turn produce a secondary electromagnetic signal B r。
Distributed in the xy plane on the array of
In this embodiment, there are five cube-
The illustration in fig. 2a represents the measuring principle as an illustration of a section in the plane II-II of fig. 1. Hereby, the detector unit 1 is moved at a substantially arbitrary depth below the surface of the body of water WO at a velocity v at a distance d above the surface of the indicated sea bed BO of the sea bed; in this case exactly in the direction of the y-axis and on line 2. The distance d can be determined accurately by means of sonar measurements or similar known means also provided on the detector unit 1, without further disclosure. The transmission coils 3, 3', 3 "and the
The excitation coils 3, 3 ', 3 "all lie in the xy-plane and emit electromagnetic pulses that are time-shifted with respect to each other as primary signals, as indicated by the different field lines B, B' and B" in fig. 2 a.
The illustration in fig. 2B shows the emission of a secondary signal B in response to a current induced in the conductive body of the line 2 buried under the earth's surface or sea bed BO
rDuring which the section extends in the plane II-II of fig. 1. Due to the general three-dimensional nature of the magnetic field, the response signal B depends on the position of the
On an array of
Since the
This effect can be used to reduce the effects of noise, for example. Due to the longitudinal extension of the wire 2 and the form of the resulting field, the response signal B is present on this extension axis y rThe evaluation of (a) is almost informative. This means that measurement and calculation effort can be saved here.
In an exemplary embodiment, each
Finally, the time decay at maximum amplitude was measured for three different diameter cables in the same field. Of course, the best and strongest response is given by the cable having the larger diameter. However, it was found in the measurements that the response signal can be used up to 10ms after switching the primary signal. A time lag Δ t in the range of 400 to 550 μ s, achieved by suitable switching means, enables the data derived from the respective measurements to be analysed, still yielding powerful and reliable results for measuring the thickness Δ of the covering layer on the line 2 under examination.
List of reference numerals
1 device/Detector Unit
2 line
3. 3', 3 "; excitation coil/transmission coil
4 receiving coil
5 cube-shaped receiver unit
5' staggered cube-shaped receiver units, still considered to be xy-plane configurations
B. B ', B' electromagnetic excitation pulse, primary pulse
B rSecondary signal responsive to current induced in conductive body by primary pulse B, B', B ″
BO seabed surface
d height of the detector unit 1 above the seabed surface BO
Distance of the detector unit 1 from the line 2
Center axis of M line 2
Velocity V
Surface of WO Water
Axes of a cartesian x, y, z coordinate system
Delta thickness of the overlay on line 2
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