CN113433489B - Distributed transient magnetic field measuring device and method - Google Patents

Abstract

The invention discloses a distributed transient magnetic field measurement device and method. The device includes: a multi-grid metal network component includes: a plurality of grids, each grid includes: a grid circuit composed of metal pipe conductors and resistors connected in series in the grid loop; multi-channel signal acquisition equipment for measuring the voltage across the resistors in each grid loop to obtain the voltage across each resistor; main processing equipment for The voltage across each resistor calculates the induced current for each grid, and the magnetic induction at each grid is calculated from the induced currents for all grids. The invention breaks through the limitation of inductive measurement of magnetic field by a single metal loop. By constructing a multi-mesh metal network, the magnetic field distribution is reversed from the current distribution, and multi-point synchronous measurement is realized. , which created the conditions for the experiment to obtain the spatial distribution characteristics of the magnetic field.

Description

A distributed transient magnetic field measurement device and method

technical field

The present invention relates to the technical field of magnetic field environment measurement, and more particularly, to a distributed transient magnetic field measurement device and method.

Background technique

Transient magnetic fields are generated in space during switching operations of substations, with large amplitudes, short rise times and wide frequency bands, which may interfere with the normal operation of secondary equipment arranged locally in the switch yard. It is a very important research method to obtain the magnetic field distribution characteristics by measurement, which provides guidance and basis for the immunity requirements of the secondary equipment and the electromagnetic compatibility design of the secondary equipment.

Magnetic field measurement at home and abroad mainly adopts B-DOT sensor, B-DOT adopts loop antenna, under the action of changing magnetic field, the loop inductance generates induced electromotive force, and the output of the load resistance is in differential mode, and the magnetic field waveform can be obtained after the integrator. Loop antennas are also widely used in electromagnetic environment measurement. When used in conjunction with receivers, they can obtain frequency domain signals, which are suitable for continuous pulse measurement, but have great limitations in electromagnetic transient measurement in substations. Magnetic field sensors based on the Faraday magneto-optical effect have also gained some applications, but they are easily affected by air humidity, mechanical vibration, etc., and the measurement stability is poor. The measurement systems established by the above-mentioned magnetic field measurement methods can only measure the magnetic field at a single position (that is, a single sensor corresponds to a single position). Measurement systems, with poor technoeconomics, are often difficult to implement.

SUMMARY OF THE INVENTION

The present invention proposes a distributed transient magnetic field measurement device and method to solve the problem of how to realize the distributed measurement of the transient magnetic field.

In order to solve the above problems, according to an aspect of the present invention, a distributed transient magnetic field measurement device is provided, the device includes: a multi-mesh metal network component, a multi-channel signal acquisition device and a main processing device; wherein,

The multi-mesh metal network member includes: a plurality of meshes, each mesh including: a mesh loop composed of metal pipe conductors and a resistor connected in series in the mesh loop;

The multi-channel signal acquisition device is connected to the resistors in each grid loop, and is used to measure the voltage across the resistors in each grid loop to obtain the voltage across each resistor;

The main processing device, connected to the multi-channel signal acquisition device, is configured to calculate the induced current of each grid according to the voltage, and calculate the magnetic induction intensity at each grid according to the induced currents of all grids.

Preferably, the inside of the metal tube conductor is a hollow structure, the metal tube conductor is disconnected at the resistance and connected to both ends of the resistance, and the measurement cable between the multi-channel signal acquisition device and the resistance is connected to the two ends of the resistance, so The measurement cable is routed within the metal conductor tube.

Preferably, the device further comprises: a plurality of signal isolation devices; wherein,

Each signal isolation device is arranged between the multi-channel signal acquisition device and the resistors in each grid loop, and the signal isolation device is used to separate the signal in the measurement loop composed of the resistor and the signal isolation device from the signal isolation device and The signals in the acquisition loop composed of multi-channel signal acquisition equipment are isolated; the signal isolation equipment corresponds to the resistance one by one.

Preferably, the signal isolation device is a broadband electronic transformer or a differential circuit.

Preferably, wherein the device further comprises:

A shielding device arranged outside the signal isolation device and/or the multi-channel signal acquisition device, the shielding device is located directly below the multi-mesh metal network member, the shielding device and the hollow of the multi-mesh metal network member Structural overlaps form a complete shield.

Preferably, the main processing device calculates the magnetic induction intensity at each grid according to the induced currents of all grids according to the following formula, including:

，

,

，

,

，

,

为第k个网格处的磁感应强度；

为第k个网格处的磁通量；

为第k个网格的面积；

为第i个边线在对应的网格的第一预设位置内产生的磁感应强度；

为空气磁导率；

为第i个边线上的电流；

为网格边线向量；

为第i个边线上的第二预设位置指向对应的网格的第一预设位置的单位向量；

为第i个边线上的第二预设位置与对应的网格的第一预设位置的距离。in,

is the magnetic induction intensity at the kth grid;

is the magnetic flux at the kth grid;

is the area of the kth grid;

is the magnetic induction intensity generated by the i-th edge in the first preset position of the corresponding grid;

is the air permeability;

is the current on the i-th edge;

is the grid edge vector;

is a unit vector that points to the first preset position of the corresponding grid for the second preset position on the i-th edge;

is the distance between the second preset position on the ith edge and the first preset position of the corresponding grid.

According to another aspect of the present invention, a distributed transient magnetic field measurement method is provided, the method comprising:

Obtain the voltage across each resistor of each grid in the multi-grid metal network member;

The induced current of each grid is calculated from the voltage, and the magnetic induction at each grid is calculated from the induced currents of all grids.

Preferably, the method further comprises: using a signal isolation device to isolate the signal in the measurement loop composed of the resistance and the signal isolation device from the signal in the acquisition loop composed of the signal isolation device and the multi-channel signal acquisition device; wherein, the signal There is a one-to-one correspondence between isolation devices and resistors.

Preferably, the method further includes: the signal isolation device is a broadband electronic transformer or a differential circuit.

Preferably, the calculation of the magnetic induction intensity at each grid according to the induced currents of all grids includes:

，

,

，

,

，

,

为第k个网格处的磁感应强度；

为第k个网格处的磁通量；

为第k个网格的面积；

为第i个边线在对应的网格的第一预设位置内产生的磁感应强度；

为空气磁导率；

为第i个边线上的电流；

为网格边线向量；

为第i个边线上的第二预设位置指向对应的网格的第一预设位置的单位向量；

为第i个边线上的第二预设位置与对应的网格的第一预设位置的距离。in,

is the magnetic induction intensity at the kth grid;

is the magnetic flux at the kth grid;

is the area of the kth grid;

is the magnetic induction intensity generated by the i-th edge in the first preset position of the corresponding grid;

is the air permeability;

is the current on the i-th edge;

is the grid edge vector;

is a unit vector that points to the first preset position of the corresponding grid for the second preset position on the i-th edge;

is the distance between the second preset position on the ith edge and the first preset position of the corresponding grid.

The invention provides a distributed transient magnetic field measurement device and method. The device includes: a multi-mesh metal network component, a multi-channel signal acquisition device and a main processing device; wherein, the multi-mesh metal network component includes: a plurality of grids, each grid includes: a grid circuit composed of metal tube conductors and a resistor connected in series in the grid circuit; the multi-channel signal acquisition device is used to detect two resistances in each grid circuit Measure the voltage across each resistor to obtain the voltage across each resistor; the main processing device is used to calculate the induced current of each grid according to the voltage across each resistor, and calculate each grid based on the induced currents of all grids Magnetic induction intensity at the grid. The invention breaks through the limitation of a single metal loop inductively measuring the magnetic field. By constructing a multi-mesh metal network, the magnetic field distribution is reversed from the current distribution, so as to realize multi-point synchronous measurement. It has created the conditions for the experiment to obtain the spatial distribution characteristics of the magnetic field.

Description of drawings

Exemplary embodiments of the present invention may be more fully understood by reference to the following drawings:

FIG. 1 is a schematic structural diagram of a distributed transient magnetic field measurement device 100 according to an embodiment of the present invention;

2 is a schematic diagram of a multi-mesh metal network member according to an embodiment of the present invention;

FIG. 3 is a flowchart of a distributed transient magnetic field measurement method 300 according to an embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for the purpose of this thorough and complete disclosure invention, and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings are not intended to limit the invention. In the drawings, the same elements/elements are given the same reference numerals.

Unless otherwise defined, terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is to be understood that terms defined in commonly used dictionaries should be construed as having meanings consistent with the context in the related art, and should not be construed as idealized or overly formal meanings.

FIG. 1 is a schematic structural diagram of a distributed transient magnetic field measurement apparatus 100 according to an embodiment of the present invention. The distributed transient magnetic field measurement device provided by the embodiment of the present invention breaks through the limitation of a single metal loop to inductively measure the magnetic field. By constructing a multi-mesh metal network, the magnetic field distribution is reversed from the current distribution, thereby realizing multi-point synchronous measurement. The ability of a set of devices to simultaneously measure transient magnetic fields at multiple locations creates conditions for experimentally obtaining the spatial distribution characteristics of magnetic fields. The distributed transient magnetic field measurement device 100 provided by the embodiment of the present invention includes: a multi-mesh metal network component 101 , a multi-channel signal acquisition device 102 and a main processing device 103 .

Preferably, the multi-mesh metal network member 101 includes: a plurality of meshes, each mesh including: a mesh loop composed of metal pipe conductors and a resistor connected in series in the mesh loop.

Preferably, the inside of the metal tube conductor is a hollow structure, the metal tube conductor is disconnected at the resistance and connected to both ends of the resistance, and the measurement cable between the multi-channel signal acquisition device and the resistance is connected to the two ends of the resistance, so The measurement cable is routed within the metal conductor tube.

Preferably, the multi-channel signal acquisition device 102 is connected to the resistors in each grid loop, and is used to measure the voltage across the resistors in each grid loop to obtain the voltage across each resistor.

2 is a schematic diagram of a multi-mesh metal network member according to an embodiment of the present invention. As shown in FIG. 2 , it is a multi-mesh metal network structure including 9 meshes, and each mesh is connected with a resistor in series. By measuring the voltage across each resistor, the induced current i of each grid is calculated, and then the magnetic induction intensity B at each grid can be calculated according to the induced current of each grid, realizing the distributed measurement of the magnetic field.

Among them, the relationship between the grid area and the resistance is: for the same low frequency bandwidth requirement, the larger the grid area is, the larger the resistance value of the resistor is. The relationship between the total area, the number of grids and the resolution is: for the same total area, the more grids, the smaller the area of a single grid, and the higher the resolution of the measurement space; at the same time, the resistance amplitude needs to be reduced, The resolution of the measured magnetic field amplitude is reduced accordingly.

The number of grids can be set as required. For example, 4, 9, 16, 25, etc.

Preferably, the device further comprises: a plurality of signal isolation devices; wherein,

Each signal isolation device is arranged between the multi-channel signal acquisition device and the resistors in each grid loop, and the signal isolation device is used to separate the signal in the measurement loop composed of the resistor and the signal isolation device from the signal isolation device and The signals in the acquisition loop composed of multi-channel signal acquisition equipment are isolated; the signal isolation equipment corresponds to the resistance one by one.

Preferably, the signal isolation device is a broadband electronic transformer or a differential circuit.

Preferably, wherein the device further comprises:

A shielding device arranged outside the signal isolation device and/or the multi-channel signal acquisition device, the shielding device is located directly below the multi-mesh metal network member, the shielding device and the hollow of the multi-mesh metal network member The structure is overlapped to form a complete shield. Since the induced current of each grid is obtained by measuring the voltage of the small resistor in series, the voltage of the small resistor is transmitted to the oscilloscope through the coaxial cable for acquisition. In order to accurately measure the voltage signal, two measures are needed to ensure that: First, the measurement loop cannot be disturbed by the space magnetic field. For this reason, a built-in shielding method is proposed: the grid loop is selected as a hollow metal tube conductor, and the tube conductor is in a small resistance. The two ends of the small resistance are disconnected and connected at the same place; the measuring cable is also connected to the two ends of the small resistance. The key point is that the measuring cable is wired in the metal tube to prevent external magnetic field interference.

Second, the same reference potential must be determined during the synchronous acquisition of multiple measurement loops. For this purpose, a signal isolation method is proposed: one method uses broadband electronic transformers to achieve signal isolation, and each broadband electronic transformer is set at each Between the signal acquisition device and the resistance in each grid loop, the broadband electronic transformer can combine the signal in the measurement loop composed of the resistance and the broadband electronic transformer with the broadband electronic transformer and the multi-channel signal acquisition device. The signal in the acquisition loop is isolated. Another method is to use a differential voltage measurement method based on operational amplifiers, so that all signals are at the same reference potential and then output to an oscilloscope (multi-channel signal acquisition device) for acquisition; three operational amplifiers are used to form a differential circuit input The input is the voltage signal at both ends of the resistor, and the output is to each port of the multi-channel signal acquisition device, so that the voltage information at both ends of all the resistors is at the same reference potential, so as to achieve signal isolation and solve the problem that each measurement loop has no reference ground.

In the present invention, the inside of the metal tube conductor is a hollow structure, the metal tube conductor is disconnected at the resistor and connected to both ends of the resistor, and the measurement cable between the resistors is wired in the metal conductor tube, and is routed through a broadband electronic transformer or The operational amplifier differential circuit realizes the unification of the reference ground, and then connects to the multi-channel signal acquisition equipment. The broadband electronic transformer or operational amplifier differential circuit and the multi-channel signal acquisition device are located in the same shielding device; the shielding device is directly under the metal grid, and is reliably overlapped with the hollow structure of the metal grid to form a complete shielding body.

Preferably, the main processing device 103 is connected to the multi-channel signal acquisition device, and is configured to calculate the induced current of each grid according to the voltage across each resistor, and calculate the induced current of each grid according to the induced current of all grids. Magnetic induction at the grid.

Preferably, wherein the main processing device calculates the magnetic induction intensity at each grid according to the induced currents of all grids, including:

，

,

，

,

，

,

为第k个网格处的磁感应强度；

为第k个网格处的磁通量；

为第k个网格的面积；

为第i个边线在对应的网格的第一预设位置内产生的磁感应强度；

为空气磁导率；

为第i个边线上的电流；

为网格边线向量；

为第i个边线上的第二预设位置指向对应的网格的第一预设位置的单位向量；

为第i个边线上的第二预设位置与对应的网格的第一预设位置的距离。in,

is the magnetic induction intensity at the kth grid;

is the magnetic flux at the kth grid;

is the area of the kth grid;

is the magnetic induction intensity generated by the i-th edge in the first preset position of the corresponding grid;

is the air permeability;

is the current on the i-th edge;

is the grid edge vector;

is a unit vector that points to the first preset position of the corresponding grid for the second preset position on the i-th edge;

is the distance between the second preset position on the ith edge and the first preset position of the corresponding grid.

。The measurement principle of the embodiment of the present invention is as follows: constructing a multi-grid metal network construction, under the action of a transient magnetic field, the metal grid will generate an induced current distribution, which is sampled by arranging small resistors in each grid, and the method to get the current. If the small resistance is R (known), the voltage U across the resistance is measured, and the induced current can be calculated by voltammetry:

.

For a single ring (or called: a single grid), satisfy:

，

,

In the formula, L is the loop inductance, S is the loop area, t is the time, and B is the magnetic induction intensity.

，高于该频率时，可近似认为

，即在环内实现磁通量的近似抵消，从而实现自积分的效果。假设电阻为1 Ω，电感为1 μH，则-3 dB低频带宽为160 kHz。The low frequency cutoff frequency is

, above this frequency, it can be approximated that

, that is, the approximate cancellation of the magnetic flux is realized in the ring, so as to realize the effect of self-integration. Assuming a resistance of 1 Ω and an inductance of 1 μH, the -3 dB low frequency bandwidth is 160 kHz.

For the multi-mesh metal network components shown in Figure 2, there is a similar law. For the magnetic field components above the low frequency bandwidth, it is considered that the integral (ie, the magnetic flux) of the scattered magnetic field generated by the induced current in each grid completely cancels the incident magnetic field. the magnetic flux.

，那么入射场经过单一环的磁通量为

。散射磁场为所有金属环的电流在环内产生的磁场，散射场经过单一环的磁通量

可基于整个金属环的环电流分布进行计算。入射磁通量与散射磁通量二者相抵消，即

。For the multi-grid metal network component shown in Figure 2, if the grid current distribution is obtained by measurement, then the magnetic field at the grid position can be obtained by integrating the scattered magnetic field generated by the unit long-line current and integrating in a grid. The magnetic field of other grid positions can be obtained, so as to realize the simultaneous measurement of the magnetic field of multiple positions. Principle description: Suppose the average magnetic induction intensity of the incident magnetic field at a certain ring position is

, then the magnetic flux of the incident field passing through a single ring is

. The scattering magnetic field is the magnetic field generated by the currents of all metal rings within the ring, and the magnetic flux of the scattering field passing through a single ring

The calculation can be made based on the ring current distribution of the entire metal ring. The incident magnetic flux and the scattered magnetic flux cancel each other out, namely

.

In the present invention, the grid current distribution has been measured, and the current of a single grid edge (marked as i, i=1, 2, . Let the magnetic induction intensity generated by the position be:

，

,

The magnetic flux generated by all edge currents in the grid k to be calculated is:

，

,

Thus, the magnetic induction intensity at grid k can be obtained as:

，

,

为第k个网格处的磁感应强度；

为第k个网格处的磁通量；

为第k个网格的面积；

为第i个边线在对应的网格的第一预设位置内产生的磁感应强度；

为空气磁导率；

为第i个边线上的电流；

为网格边线向量；

为第i个边线上的第二预设位置指向对应的网格的第一预设位置的单位向量；

为第i个边线上的第二预设位置与对应的网格的第一预设位置的距离。in,

is the magnetic induction intensity at the kth grid;

is the magnetic flux at the kth grid;

is the area of the kth grid;

is the magnetic induction intensity generated by the i-th edge in the first preset position of the corresponding grid;

is the air permeability;

is the current on the i-th edge;

is the grid edge vector;

is a unit vector that points to the first preset position of the corresponding grid for the second preset position on the i-th edge;

is the distance between the second preset position on the ith edge and the first preset position of the corresponding grid.

In the present invention, the first preset position and the second preset position are set according to calculation requirements. The distributed transient magnetic field measurement device of the present invention has a set of devices to realize the multi-point synchronous measurement capability of the transient magnetic field, so that the spatial distribution characteristics of the magnetic field can be accurately obtained, and the electromagnetic compatibility immunity of the switch field equipment of the substation can be accurately proposed. Degree requirements provide a basis, and the application prospect and scale are huge.

FIG. 3 is a flowchart of a magnetic field measurement method 300 using a distributed transient magnetic field measurement device according to an embodiment of the present invention. As shown in FIG. 3 , the magnetic field measurement method 300 using the above-mentioned distributed transient magnetic field measurement device provided by the embodiment of the present invention includes:

Step 301: Obtain the voltage across each resistor of each grid in the multi-grid metal network component.

Step 302: Calculate the induced current of each grid according to the voltage, and calculate the magnetic induction intensity at each grid according to the induced currents of all grids.

Preferably, wherein the method further comprises:

Signal isolation equipment is used to isolate the signal in the measurement loop composed of resistance and signal isolation equipment from the signal in the acquisition circuit composed of signal isolation equipment and multi-channel signal acquisition equipment; among them, the signal isolation equipment corresponds to the resistance one-to-one.

Preferably, the signal isolation device is a broadband electronic transformer or a differential circuit.

Preferably, wherein the

The magnetic induction at each grid is calculated from the induced currents for all grids, including:

，

,

，

,

，

,

为第k个网格处的磁感应强度；

为第k个网格处的磁通量；

为第k个网格的面积；

为第i个边线在对应的网格的第一预设位置内产生的磁感应强度；

为空气磁导率；

为第i个边线上的电流；

为网格边线向量；

为第i个边线上的第二预设位置指向对应的网格的第一预设位置的单位向量；

为第i个边线上的第二预设位置与对应的网格的第一预设位置的距离。in,

is the magnetic induction intensity at the kth grid;

is the magnetic flux at the kth grid;

is the area of the kth grid;

is the magnetic induction intensity generated by the i-th edge in the first preset position of the corresponding grid;

is the air permeability;

is the current on the i-th edge;

is the grid edge vector;

is a unit vector that points to the first preset position of the corresponding grid for the second preset position on the i-th edge;

is the distance between the second preset position on the ith edge and the first preset position of the corresponding grid.

The distributed transient magnetic field measurement method 300 in the embodiment of the present invention corresponds to the distributed transient magnetic field measurement apparatus 100 in another embodiment of the present invention, and details are not described herein again.

The present invention has been described with reference to a few embodiments. However, as is known to those skilled in the art, other embodiments than the above disclosed invention are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/the/the [means, component, etc.]" are open to interpretation as at least one instance of said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowcharts and/or block diagrams, and combinations of flows and/or blocks in the flowcharts and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for the functionality that would be specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions An apparatus implements the functions specified in a flow or flows of the flowcharts and/or a block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for the functions to be specified in a flow or flows of the flowcharts and/or a block or blocks of the block diagrams.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications or equivalent replacements are made to the specific embodiments of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. A distributed transient magnetic field measurement device, characterized in that the device comprises: a multi-grid metal network component, a multi-channel signal acquisition device and a main processing device; wherein, The multi-mesh metal mesh member includes: a plurality of meshes, each mesh comprising: a mesh loop composed of metal conductor tubes and a resistor connected in series in the mesh loop; The multi-channel signal acquisition device is connected to the resistors in each grid loop, and is used to measure the voltage across the resistors in each grid loop to obtain the voltage across each resistor; The main processing device is connected to the multi-channel signal acquisition device, and is used to calculate the induced current of each grid according to the voltage across each resistor, and calculate the induced current at each grid according to the induced currents of all grids. Magnetic induction. 2 . The device according to claim 1 , wherein the inside of the metal conductor tube is a hollow structure, the metal conductor tube is disconnected at the resistance and connected to both ends of the resistance, and the multi-channel signal acquisition device and the resistance are connected. 3 . The measurement cables are connected at both ends of the resistance, and the measurement cables are routed in the metal conductor tube. 3. The apparatus according to claim 1, wherein the apparatus further comprises: a plurality of signal isolation devices; wherein, Each signal isolation device is arranged between the multi-channel signal acquisition device and the resistors in each grid loop, and the signal isolation device is used to separate the signal in the measurement loop composed of the resistor and the signal isolation device from the signal isolation device and The signals in the acquisition loop composed of multi-channel signal acquisition equipment are isolated; the signal isolation equipment corresponds to the resistance one by one. 4. The apparatus according to claim 3, wherein the signal isolation device is a broadband electronic transformer or a differential circuit. 5. The apparatus of claim 1, wherein the apparatus further comprises: A shielding device arranged outside the signal isolation device and/or the multi-channel signal acquisition device, the shielding device is located directly below the multi-mesh metal network member, the shielding device and the hollow of the multi-mesh metal network member Structural overlaps form a complete shield. 6. The device according to claim 1, wherein the main processing device calculates the magnetic induction intensity at each grid according to the induced currents of all grids according to the following formula, including:

,

,

, in,

is the magnetic induction intensity at the kth grid;

is the magnetic flux at the kth grid;

is the area of the kth grid;

is the magnetic induction intensity generated by the i-th edge in the first preset position of the corresponding grid;

is the air permeability;

is the current on the i-th edge;

is the grid edge vector;

is a unit vector that points to the first preset position of the corresponding grid for the second preset position on the i-th edge;

is the distance between the second preset position on the ith edge and the first preset position of the corresponding grid. 7. A method for measuring a distributed transient magnetic field, wherein the method comprises: Obtain the voltage across each resistor of each grid in the multi-grid metal network member; The induced current of each grid is calculated from the voltage, and the magnetic induction at each grid is calculated from the induced currents of all grids. 8. The method according to claim 7, wherein the method further comprises: Signal isolation equipment is used to isolate the signal in the measurement loop composed of resistance and signal isolation equipment from the signal in the acquisition circuit composed of signal isolation equipment and multi-channel signal acquisition equipment; among them, the signal isolation equipment corresponds to the resistance one-to-one. 9 . The method according to claim 8 , wherein the signal isolation device is a broadband electronic transformer or a differential circuit. 10 . 10. The method according to claim 7, wherein the calculating the magnetic induction intensity at each grid according to the induced currents of all grids comprises:

,

,

, in,

is the magnetic induction intensity at the kth grid;

is the magnetic flux at the kth grid;

is the area of the kth grid;

is the magnetic induction intensity generated by the i-th edge in the first preset position of the corresponding grid;

is the air permeability;

is the current on the i-th edge;

is the grid edge vector;

is a unit vector that points to the first preset position of the corresponding grid for the second preset position on the i-th edge;

is the distance between the second preset position on the ith edge and the first preset position of the corresponding grid.

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