Non-contact current detection method and device for multi-phase power line

Abstract

The invention provides a non-contact current detection method and device for a multi-phase power line. The method comprises the steps that a first analog voltage is obtained through a first TMR sensor, and a second analog voltage is obtained through a second TMR sensor; wherein the first TMR sensor and the second TMR sensor are arranged outside the power line and are staggered along the multi-phase power line; the method comprises the following steps: reading an analog voltage of a TMR sensor by using an ADC, converting the analog voltage into a digital voltage, and carrying out FFT conversion to obtain a frequency spectrum corresponding to the digital voltage; the frequency spectrum is compared with a CFAR threshold value determined by using a CFAR algorithm, and when the amplitude value of the frequency of 40-60 hz exceeds the threshold value, it is determined that current exists; if not, the voltage of the other TMR sensor continues to be processed and judged, when the amplitude value of the frequency of 40-60 hz exceeds the threshold value, it is determined that current exists in the multi-phase power line, and if not, it is determined that current does not exist in the multi-phase power line. By means of the technical scheme, current detection can be carried out under the condition that electric wires are not invaded, and detection is safe and convenient.

Description

Technical Field

[0001] The present invention relates to the field of current detection, and particularly to a non-contact current detection method and device for a multi-phase power line. Background Art

[0002] Existing current detection methods include: using a current transformer (CT) to detect current and using a smart plug to detect current. However, both using a CT and a smart plug to detect current have some drawbacks. For example, a CT usually requires a licensed electrician for installation, and the wire needs to be modified and separately clamped on the neutral wire or the live wire, which is dangerous in operation; a smart plug is invasive and will interfere with the normal operation of the device to be detected. In short, the current detection methods in the prior art are rather troublesome, require power-off or a licensed electrician for installation, and are inconvenient to detect. Especially in the scenario where power-off detection is not possible, current detection is more difficult. Summary of the Invention

[0003] In view of the above problems in the prior art, embodiments of the present invention provide a non-contact current detection method and device for a multi-phase power line, which do not need to invade the wire during detection and are safe and convenient to use.

[0004] To achieve the above object, on the one hand, a non-contact current detection method for a multi-phase power line is provided, including:

[0005] Obtaining a first analog voltage corresponding to the magnetic field intensity at a first position of the multi-phase power line by using a first TMR sensor, and obtaining a second analog voltage corresponding to the magnetic field intensity at a second position of the multi-phase power line by using a second TMR sensor; wherein, the first TMR sensor and the second TMR sensor are arranged outside the multi-phase power line and are staggeredly placed along the extension direction of the multi-phase power line, and the distance between the first position and the second position is greater than a predetermined distance threshold;

[0006] Reading the first analog voltage by using a first channel of an analog-to-digital conversion module at a predetermined sampling frequency, converting the read first analog voltage into a first digital voltage sequence, and performing a fast Fourier transform on the first digital voltage sequence to obtain a first frequency spectrum distribution corresponding to the first digital voltage sequence;

[0007] Compare the first spectral distribution with an adaptive threshold determined using a constant false alarm rate algorithm. When the amplitude at a frequency of 40 - 60 hz exceeds the adaptive threshold, determine that there is current in the polyphase power line; otherwise, use the second channel of the analog-to-digital conversion module to read the second analog voltage at a predetermined sampling frequency, convert the read second analog voltage into a second digital voltage sequence, perform a fast Fourier transform on the second digital voltage sequence to obtain a second spectral distribution corresponding to the second digital voltage sequence, compare the second spectral distribution with the adaptive threshold, and when the amplitude at a frequency of 40 - 60 hz exceeds the adaptive threshold, determine that there is current in the polyphase power line; otherwise, determine that there is no current in the polyphase power line.

[0008] Preferably, in the non-contact current detection method, the first TMR sensor and the second TMR sensor are respectively arranged on different sides of the polyphase power line.

[0009] Preferably, in the non-contact current detection method, the first TMR sensor and the second TMR sensor are arranged on a fixed seat;

[0010] The fixed seat includes: a first side plate and a second side plate connected to each other, the first side plate and the second side plate form an angle with each other, and a space for placing the polyphase power line is formed between the first side plate and the second side plate, and the space is for the polyphase power line to be placed in a direction parallel to the connection line of the first side plate and the second side plate;

[0011] The first TMR sensor and the second TMR sensor are respectively arranged on the first side plate or the second side plate, and the first TMR sensor and the second TMR sensor are located on different side plates.

[0012] Preferably, in the non-contact current detection method, when it is determined that there is current in the polyphase power line, it further includes:

[0013] Save the effective voltage amplitude that exceeds the adaptive threshold and appears within the frequency range of 40 - 60 hz;

[0014] Calculate the ratio M of the effective voltage amplitude to the current maximum voltage. If the M is less than a predetermined first ratio threshold, it is determined that the polyphase power line is currently in a low output power state. If the M is greater than or equal to the first ratio threshold and less than or equal to a predetermined second ratio threshold, it is determined that the polyphase power line is currently in a medium power state. If the M is greater than the second ratio threshold, it is determined that the polyphase power line is currently in a high output power state; wherein, the first ratio threshold is less than the second ratio threshold; the first ratio threshold is less than or equal to 0.35; the second ratio threshold is greater than or equal to 0.55; wherein, the current maximum voltage is the maximum voltage updated in real time using the effective voltage amplitude.

[0015] Preferably, in the non-contact current detection method, the first ratio threshold is 0.3 and the second ratio threshold is 0.6.

[0016] On the other hand, there is also provided a non-contact current detection device for a polyphase power line for implementing any one of the above, including:

[0017] A first TMR sensor and a second TMR sensor; wherein, the first TMR sensor and the second TMR sensor are arranged outside the polyphase power line and staggeredly placed along the extension direction of the polyphase power line, and are respectively used to obtain a first analog voltage corresponding to the magnetic field intensity at a first position of the polyphase power line and a second analog voltage corresponding to the magnetic field intensity at a second position of the polyphase power line; wherein, the distance between the first position and the second position is greater than a predetermined distance threshold;

[0018] An analog-to-digital conversion module, including at least a first channel and a second channel. The first channel is used to receive the first analog voltage output by the first TMR sensor, the second channel is used to receive the second analog voltage output by the second TMR sensor, and the analog-to-digital conversion module is used to read the first analog voltage and the second analog voltage at a predetermined sampling frequency, and convert the read first analog voltage and second analog voltage into corresponding first digital voltage sequences and second digital voltage sequences;

[0019] A controller is configured to perform a fast Fourier transform on the first digital voltage sequence to obtain a first spectral distribution corresponding to the first digital voltage sequence, and compare the first spectral distribution with an adaptive threshold determined using a constant false alarm rate algorithm. When the amplitude at a frequency of 40 - 60 Hz exceeds the adaptive threshold, it is determined that there is current in the polyphase power line; otherwise, a fast Fourier transform is performed on the second digital voltage sequence to obtain a second spectral distribution corresponding to the second digital voltage sequence, and the second spectral distribution is compared with the adaptive threshold. When the amplitude at a frequency of 40 - 60 Hz exceeds the adaptive threshold, it is determined that there is current in the polyphase power line; otherwise, it is determined that there is no current in the polyphase power line.

[0020] Preferably, for the non - contact current detection device, the first TMR sensor and the second TMR sensor are respectively arranged on different sides of the polyphase power line.

[0021] Preferably, for the non - contact current detection device, the first TMR sensor and the second TMR sensor are arranged on a fixed seat.

[0022] The fixed seat includes: a first side plate and a second side plate connected to each other. The first side plate and the second side plate form an angle with each other, and a space for placing the polyphase power line is formed between the first side plate and the second side plate. The space is used for the polyphase power line to be placed in a direction parallel to the connection line of the first side plate and the second side plate.

[0023] The first TMR sensor and the second TMR sensor are respectively arranged on the first side plate or the second side plate, and the first TMR sensor and the second TMR sensor are located on different side plates.

[0024] Preferably, for the non - contact current detection device, wherein the controller is further configured to perform the following steps when it is determined that there is current in the polyphase power line:

[0025] Save the effective voltage amplitudes that exceed the adaptive threshold and appear within the frequency range of 40 - 60 Hz.

[0026] Calculate the ratio M of the effective voltage amplitude to the current maximum voltage. If the M is less than a predetermined first ratio threshold, it is determined that the multi-phase power line is currently in a low output power state. If the M is greater than or equal to the first ratio threshold and less than or equal to a predetermined second ratio threshold, it is determined that the multi-phase power line is currently in a medium power state. If the M is greater than the second ratio threshold, it is determined that the multi-phase power line is currently in a high output power state. Wherein, the first ratio threshold is less than the second ratio threshold; the first ratio threshold is less than or equal to 0.35; the second ratio threshold is greater than or equal to 0.55. Wherein, the current maximum voltage is the maximum voltage updated in real time using the effective voltage amplitude.

[0027] Preferably, the non-contact current detection device further includes one or more of the following:

[0028] A LORA communication module, connected to the controller, for uploading the result of whether there is current determined by the controller to a cloud server;

[0029] An indication module for indicating the result of whether there is current determined by the controller.

[0030] The technical solution of the embodiment of the present invention detects whether there is current at different positions of the same multi-phase power line through two TMR sensors arranged at different positions, avoiding the defect of false detection that may occur when only one TMR sensor is used and its installation position happens to be at the position where the neutral line and the live line cancel each other out. It realizes non-contact current detection. Moreover, further, by adopting the CFAR algorithm to provide an adaptive voltage threshold for comparison, the influence of background noise on current detection can be overcome. And, the device of the present invention only needs to be placed outside the multi-phase power line of the device to be measured, such as buckled on the interface of the multi-phase power line of the device to be measured during detection, without modifying the wires, and can realize non-invasive detection. The detection process is safe and simple. The detection personnel do not need to be a licensed electrician and will not interfere with the normal operation of the device, which is especially beneficial for current detection in scenarios where power cannot be cut off.

[0031] Further, when there is current in the wire, the present invention uses an adaptive comparison algorithm to determine whether the current output of the current device is high power, medium power or low power. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic flowchart of a non-contact current detection method for a multi-phase power line according to an embodiment of the present invention;

[0033] Figure 2 It is a schematic layout diagram of two TMR sensors in an embodiment of the present invention;

[0034] Figure 3 Structural schematic diagram of a detection device for a non-contact current detection method for a multi-phase power line according to an embodiment of the present invention;

[0035] Figure 4 Schematic diagram for current analysis of the spectrogram obtained after FFT transformation;

[0036] Figure 5 Schematic flow diagram for determining the current power state of a multi-phase power line in an embodiment. Detailed implementation manners

[0037] To further illustrate the embodiments, the present invention provides accompanying drawings. These accompanying drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used to explain the operating principle of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0038] The principle of the technical solution of the present invention is to detect the weak magnetic fields generated by the neutral wire and the live wire wound around the power line, and utilize the principle of electromagnetic induction to convert the magnetic field intensity into the magnitude of the current. Specifically, when an electric current passes through a conductor, a magnetic field proportional to the current will be generated. These weak magnetic field signals can be captured by a highly sensitive magnetic field sensor such as a tunneling magnetoresistance (TMR) sensor.

[0039] The inventors of the present application found that: in a multi-phase power line, the current directions of the neutral wire and the live wire are opposite, and theoretically, opposite magnetic fields will be generated, which will cancel each other out; however, due to the existence of small imbalances and leakage magnetic fields in the actual current, these magnetic field signals that are not completely canceled can be detected; for this reason, the present application uses at least two highly sensitive TMR sensors, through precise arrangement and calibration, to effectively capture and amplify these weak magnetic field signals. Because the magnetic field signals at different positions in the power line are different, the corresponding current values are also different. Therefore, when a TMR sensor at one position detects no current, another TMR sensor set at a different position can be used to verify whether there is current to ensure the accuracy of the detection.

[0040] Specifically, the magnetic field signals captured by the TMR sensor are amplified and filtered by the built-in signal processing unit to remove noise and interference, and are output in the form of an analog voltage; then, they are converted through an analog-to-digital conversion module (ADC) to obtain the current detection result.

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0042] Embodiment 1:

[0043] A non-contact current detection method for a multi-phase power line according to an embodiment of the present invention includes:

[0044] Obtaining a first analog voltage corresponding to the magnetic field intensity at a first position of the multi-phase power line using a first TMR sensor, and obtaining a second analog voltage corresponding to the magnetic field intensity at a second position of the multi-phase power line using a second TMR sensor; wherein, the first TMR sensor and the second TMR sensor are arranged outside the multi-phase power line and are staggeredly arranged along the extension direction of the multi-phase power line, and the distance between the first position and the second position is greater than a predetermined distance threshold; preferably, the predetermined distance threshold is greater than or equal to 3 centimeters;

[0045] Reading the first analog voltage using the first channel of the analog-to-digital conversion module at a predetermined sampling frequency, converting the read first analog voltage into a first digital voltage sequence, and performing a fast Fourier transform on the first digital voltage sequence to obtain a first spectrum corresponding to the first digital voltage sequence;

[0046] Comparing the first spectrum distribution with an adaptive threshold determined using the Constant False-Alarm Rate (CFAR) algorithm. When the amplitude at a frequency of 40 - 60 hz exceeds the adaptive threshold, it is determined that there is current in the multi-phase power line; otherwise, reading the second analog voltage using the second channel of the analog-to-digital conversion module at a predetermined sampling frequency, converting the read second analog voltage into a second digital voltage sequence, performing a fast Fourier transform on the second digital voltage sequence to obtain a second spectrum distribution corresponding to the second digital voltage sequence, comparing the second spectrum distribution with the adaptive threshold, and when the amplitude at a frequency of 40 - 60 hz exceeds the CFAR adaptive threshold, it is determined that there is current in the multi-phase power line, otherwise, it is determined that there is no current in the multi-phase power line, that is, there is alternating current.

[0047] In other embodiments, more than two TMR sensors can also be deployed to detect whether there is current.

[0048] Further, after determining that there is current in the multi-phase power line, it is indicated by a corresponding indicator such as an indicator light.

[0049] Specifically, Figure 1 is a schematic flow diagram of a non-contact current detection method for a multi-phase power line according to an embodiment of the present invention. Figure 1 In, TMR1 is the first TMR sensor, and TMR2 is the second TMR2 sensor. As Figure 1, in the method of this embodiment, first, the ADC data of TMR1 is acquired. After performing FFT transformation, according to the transformation result of FFT, CFAR threshold algorithm detection is carried out, that is, the transformation result of FFT is compared with the adaptive threshold determined by the CFAR algorithm; it is judged whether the amplitude at the frequency of 40 - 60HZ is greater than the current CFAR threshold; if so, it is determined that there is current, and the voltage amplitude V1 of this point is saved, and the presence of current is indicated by lighting an indicator; otherwise, the indicator light is not on, indicating that there is no current at present; and the ADC channel is switched to read the ADC data of the second TMR sensor, that is, TMR2. For the ADC data of TMR2, the same processing and judgment as for the ADC data of TMR1 are carried out, and finally it is determined whether there is current. Among them, ADC (Analog-to-digital converter) is the analog-to-digital converter.

[0050] Preferably, the first TMR sensor and the second TMR sensor are respectively arranged on different sides of the multi-phase power line. As Figure 2 shown, in a specific implementation, the first TMR sensor, that is, TMR1, and the second TMR sensor, that is, TMR2, are arranged on a fixed seat; the fixed seat includes: a first side plate and a second side plate connected to each other, the first side plate and the second side plate form an angle with each other, and a space for placing the multi-phase power line is formed between the first side plate and the second side plate, and the space is used for the multi-phase power line to be placed along the direction parallel to the connection line of the first side plate and the second side plate; the first TMR sensor and the second TMR sensor are respectively arranged on the first side plate or the second side plate, and the first TMR sensor and the second TMR sensor are located on different side plates. The fixed seat in the figure is only exemplary. In a specific implementation, the fixed seat can be integrally formed or different parts can be connected by connecting pieces. Preferably, the first side plate and the second side plate form a 90-degree angle.

[0051] Embodiment Two:

[0052] The present invention also provides a detection device for implementing the non-contact current detection method for multi-phase power lines described above. The detection device includes:

[0053] a first TMR sensor and a second TMR sensor; wherein, the first TMR sensor and the second TMR sensor are arranged outside the multi-phase power line and are staggeredly placed along the extending direction of the multi-phase power line, and are respectively used to obtain a first analog voltage corresponding to the magnetic field intensity at the first position of the multi-phase power line and a second analog voltage corresponding to the magnetic field intensity at the second position of the multi-phase power line; wherein, the distance between the first position and the second position is greater than a predetermined distance threshold;

[0054] The analog-to-digital conversion module includes at least a first channel and a second channel. The first channel is used to receive a first analog voltage output by a first TMR sensor, and the second channel is used to receive a second analog voltage output by a second TMR sensor. The analog-to-digital conversion module is used to read the first analog voltage and the second analog voltage at a predetermined sampling frequency, and convert the read first analog voltage and second analog voltage into corresponding first digital voltage sequence and second digital voltage sequence;

[0055] The controller is used to perform a fast Fourier transform on the first digital voltage sequence to obtain a first spectrum distribution corresponding to the first digital voltage sequence, and compare the first spectrum distribution with an adaptive threshold determined using a constant false alarm rate algorithm. When the amplitude at a frequency of 40 - 60 hz exceeds the adaptive threshold, it is determined that there is current in the polyphase power line; otherwise, the second digital voltage sequence is subjected to a fast Fourier transform to obtain a second spectrum distribution corresponding to the second digital voltage sequence, and the second spectrum distribution is compared with the adaptive threshold. When the amplitude at a frequency of 40 - 60 hz exceeds the adaptive threshold, it is determined that there is current in the polyphase power line, otherwise, it is determined that there is no current in the polyphase power line.

[0056] Further, when it is detected that there is current in the polyphase power line, that is, the TMR detects the magnetic field generated by the current, the power corresponding to the current or magnetic field at the moment is further confirmed.

[0057] Figure 3 It is a schematic structural diagram of a detection device for a non-contact current detection method for a polyphase power line according to an embodiment of the present invention. As Figure 3 In this specific implementation, the analog-to-digital conversion module uses a 16-bit ADC chip of ADS1115; the controller uses an STM32WLE5 chip; it also includes a power supply for powering it, an indicator light for indicating whether there is current, and a LORA communication module for uploading the detection result of the controller to a cloud server. In this example, it is powered by a power supply module such as a 3.6V battery.

[0058] The method for current detection using the device of this embodiment specifically includes:

[0059] 1. Data acquisition: Obtain the ADC values corresponding to the detection data of different TMR sensors;

[0060] Configure the ADS1115 ADC module according to the selected channel; specifically, select different configuration parameters according to the channel and transmit the configuration data through the I2C interface. Different TMR sensors are connected to the ADC module through different channels. The MCU reads the ADC data from the ADS1115 and converts it into voltage values to obtain a sequence of voltage values. The data is received through the I2C interface and converted. In this example, the ADC data collected each time is 512, and the reading rate of the MCU to read the ADC data from the ADC module is 860 times per second.

[0061] 2. Signal preprocessing: FFT transformation;

[0062] The MCU performs FFT transformation and amplitude calculation on the above 512 ADC data read each time; and normalizes the result of the FFT and calculates the frequency. The frequency of the mains power is 50hz, so weak magnetic fields can be better captured in the frequency domain; and most of the interference can be filtered out in the frequency domain.

[0063] 3. Apply the CFAR algorithm for target detection;

[0064] According to the result after the FFT transformation, use the CFAR algorithm to calculate the voltage adaptive threshold for judging whether there is electricity. The CFAR algorithm is a target detection technology used in radar, communication, and signal processing. The core idea of the CFAR algorithm is to maintain a constant false alarm rate, that is, to adaptively adjust the detection threshold, namely the threshold, in the case of changing background noise, so as to ensure the stability of the detection performance. The steps for the CFAR algorithm to determine the threshold include:

[0065] Apply a sliding window to the signal sequence to be detected; the window is divided into a protection unit, a training unit, and a unit to be detected; the protection unit is used to avoid the influence of the target signal on the background noise estimation, and the training unit is used to estimate the background noise level;

[0066] Perform noise estimation: estimate the background noise level by the average value method for the signal values in the training unit;

[0067] Perform threshold calculation: calculate the detection threshold according to the background noise estimation value and the preset false alarm rate; the calculation of the threshold usually involves a scaling factor; preferably, the scaling factor used in the embodiments of the present invention is 1.5 to ensure detection at the set false alarm rate;

[0068] Perform target detection: compare the signal value of the unit to be detected with the calculated threshold. If the signal value exceeds the threshold, it is determined as a target signal, that is, there is current, otherwise it is determined as noise;

[0069] Figure 4 It is a schematic diagram for current analysis of the spectrogram obtained after FFT transformation. As Figure 4, three curves are presented in different colors. The red curve 1 is the spectrogram obtained after the FFT conversion of 512 ADC values read by the MCU, the blue curve 2 is the CFAR threshold curve determined by the CFAR algorithm, and the yellow curve 3 is the amplitude at the 50HZ frequency. It can be seen from this figure that the voltage amplitude corresponding to the 50HZ frequency point is greater than the CFAR threshold, so there is current in this polyphase power line at present. In this example, it happens that the voltage amplitude at the 50HZ frequency is greater than the CFAR threshold, that is, there is alternating current.

[0070] 4. Judgment of whether there is current;

[0071] When the amplitude at the frequency of 40 - 60hz in the FFT result exceeds the CFAR threshold, it is determined that there is current, and the amplitude corresponding to the current frequency point is saved; if it does not exceed the CFAR threshold, the ADC channel is switched to read the voltage value of another TMR for further judgment.

[0072] 5. Power state output;

[0073] According to the effective voltage amplitude obtained in the judgment of whether there is current, the voltage maximum value is updated in real time; then, the current voltage is compared with the voltage maximum value, and the power state of the current current is output according to the comparison result, including: low power, medium power or high power.

[0074] In a specific implementation, the power state is determined by calculating the ratio M of the effective amplitude of the current voltage to the current latest voltage maximum value; if M is less than a predetermined first ratio threshold, it is determined that the polyphase power line is currently in a low output power state, if M is greater than or equal to the first ratio threshold and less than or equal to a predetermined second ratio threshold, it is determined that the polyphase power line is currently in a medium power state, if M is greater than the second ratio threshold, it is determined that the polyphase power line is currently in a high output power state; wherein, the first ratio threshold is less than the second ratio threshold; the first ratio threshold is less than or equal to 0.35; the second ratio threshold is greater than or equal to 0.55. Preferably, the first ratio threshold is 0.3 and the second ratio threshold is 0.6.

[0075] Figure 5 It is a schematic flow chart for determining the current power state of a polyphase power line in an embodiment. As Figure 5 , determining the current power state of the polyphase power line includes:

[0076] When it is detected that there is current, it is judged whether the current effective voltage threshold V1 is greater than the current voltage maximum value VMAX; if so, the current VMAX is updated to V1; otherwise, the original VMAX is still used;

[0077] Compare V1 with VMAX. If V1 < 0.3 * VMAX, determine the current power as low power; if V1 > 0.3 * VMAX, determine the current power as high power; if it is between 0.3 * VMAX and 0.6 * VMAX, determine the current power as medium power.

[0078] Although the present invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail can be made to the present invention without departing from the spirit and scope of the present invention as defined by the appended claims, and all such changes are within the scope of protection of the present invention.

Claims

1. A non-contact current detection method for a multi-phase power line, characterized in that: include: Using a first TMR sensor to obtain a first analog voltage corresponding to the magnetic field strength at a first position of a multi-phase power line, and using a second TMR sensor to obtain a second analog voltage corresponding to the magnetic field strength at a second position of the multi-phase power line; wherein the first TMR sensor and the second TMR sensor are arranged outside the multi-phase power line and staggered along the extension direction of the multi-phase power line, and the distance between the first position and the second position is greater than a predetermined distance threshold; Using a first channel of an analog-to-digital conversion module, reading the first analog voltage at a predetermined sampling frequency, converting the read first analog voltage into a first digital voltage sequence, performing a fast Fourier transform on the first digital voltage sequence, and obtaining a first frequency spectrum distribution corresponding to the first digital voltage sequence; The first spectrum distribution is compared with an adaptive threshold determined by a constant false alarm rate algorithm, and when the amplitude at a frequency of 40 to 60 Hz exceeds the adaptive threshold, it is determined that there is current in the multi-phase power line; otherwise, the second analog voltage is read at a predetermined sampling frequency using a second channel of the analog-to-digital conversion module, and the read second analog voltage is converted into a second digital voltage sequence, and the second digital voltage sequence is fast Fourier transformed to obtain a second spectrum distribution corresponding to the second digital voltage sequence, and the second spectrum distribution is compared with the adaptive threshold, and when the amplitude at a frequency of 40 to 60 Hz exceeds the adaptive threshold, it is determined that there is current in the multi-phase power line, otherwise, it is determined that there is no current in the multi-phase power line.

2. The non-contact current detection method according to claim 1, characterized in that: The first TMR sensor and the second TMR sensor are respectively disposed at different sides of the multi-phase power line.

3. The non-contact current detection method according to claim 1, characterized in that: The first TMR sensor and the second TMR sensor are arranged on a fixing seat; The fixing seat comprises: a first side plate and a second side plate connected to each other, the first side plate and the second side plate are at an angle to each other, a space for placing the multi-phase power line is formed between the first side plate and the second side plate, and the space is used for placing the multi-phase power line in a direction parallel to the connection line between the first side plate and the second side plate; The first TMR sensor and the second TMR sensor are respectively disposed on the first side plate or the second side plate, and the first TMR sensor and the second TMR sensor are located on different side plates.

4. The non-contact current detection method according to claim 1, characterized in that: When determining that there is current in the multi-phase power line, the method further includes: Saving the effective voltage amplitude that exceeds the adaptive threshold and occurs within a frequency range of 40 to 60 Hz; Calculate the ratio M of the effective voltage amplitude to the current maximum voltage. If the M is less than a predetermined first ratio threshold, determine that the multi-phase power line is currently in a low output power state. If the M is greater than or equal to the first ratio threshold and less than or equal to a predetermined second ratio threshold, determine that the multi-phase power line is currently in a medium power state. If the M is greater than the second ratio threshold, determine that the multi-phase power line is currently in a high output power state; wherein the first ratio threshold is less than the second ratio threshold; the first ratio threshold is less than or equal to 0.35; the second ratio threshold is greater than or equal to 0.55; wherein the current maximum voltage is the maximum voltage value updated in real time using the effective voltage amplitude.

5. The non-contact current detection method according to claim 4, characterized in that: The first ratio threshold is 0.3, and the second ratio threshold is 0.

6.

6. A non-contact current detection device for a multi-phase power line for implementing any one of claims 1 to 5, characterized in that: include: a first TMR sensor and a second TMR sensor; wherein the first TMR sensor and the second TMR sensor are arranged outside the multi-phase power line and staggered along the extension direction of the multi-phase power line, and are respectively used to obtain a first analog voltage corresponding to the magnetic field strength at a first position of the multi-phase power line and a second analog voltage corresponding to the magnetic field strength at a second position of the multi-phase power line; wherein the distance between the first position and the second position is greater than a predetermined distance threshold; An analog-to-digital conversion module comprises at least a first channel and a second channel, wherein the first channel is used to receive a first analog voltage output by the first TMR sensor, and the second channel is used to receive a second analog voltage output by the second TMR sensor, and the analog-to-digital conversion module is used to read the first analog voltage and the second analog voltage at a predetermined sampling frequency, and convert the read first analog voltage and the second analog voltage into corresponding first digital voltage sequences and second digital voltage sequences; A controller is used to perform a fast Fourier transform on the first digital voltage sequence to obtain a first spectrum distribution corresponding to the first digital voltage sequence, and compare the first spectrum distribution with an adaptive threshold determined using a constant false alarm rate algorithm, and when the amplitude at a frequency of 40 to 60 Hz exceeds the adaptive threshold, determine that there is current in the multi-phase power line; otherwise, perform a fast Fourier transform on the second digital voltage sequence to obtain a second spectrum distribution corresponding to the second digital voltage sequence, and compare the second spectrum distribution with the adaptive threshold, and when the amplitude at a frequency of 40 to 60 Hz exceeds the adaptive threshold, determine that there is current in the multi-phase power line, otherwise, determine that there is no current in the multi-phase power line.

7. The non-contact current detection device according to claim 6, characterized in that: The first TMR sensor and the second TMR sensor are respectively disposed at different sides of the multi-phase power line.

8. The non-contact current detection device according to claim 6, characterized in that: The first TMR sensor and the second TMR sensor are arranged on a fixing seat; The fixing seat comprises: a first side plate and a second side plate connected to each other, the first side plate and the second side plate are at an angle to each other, a space for placing the multi-phase power line is formed between the first side plate and the second side plate, and the space is used for placing the multi-phase power line in a direction parallel to the connection line between the first side plate and the second side plate; The first TMR sensor and the second TMR sensor are respectively disposed on the first side plate or the second side plate, and the first TMR sensor and the second TMR sensor are located on different side plates.

9. The non-contact current detection device according to claim 6, characterized in that: The controller is further configured to execute the following steps when determining that there is current in the multi-phase power line: Saving the effective voltage amplitude that exceeds the adaptive threshold and occurs within a frequency range of 40 to 60 Hz; Calculate the ratio M of the effective voltage amplitude to the current maximum voltage. If the M is less than a predetermined first ratio threshold, determine that the multi-phase power line is currently in a low output power state. If the M is greater than or equal to the first ratio threshold and less than or equal to a predetermined second ratio threshold, determine that the multi-phase power line is currently in a medium power state. If the M is greater than the second ratio threshold, determine that the multi-phase power line is currently in a high output power state; wherein the first ratio threshold is less than the second ratio threshold; the first ratio threshold is less than or equal to 0.35; the second ratio threshold is greater than or equal to 0.55; wherein the current maximum voltage is the maximum voltage value updated in real time using the effective voltage amplitude.

10. The non-contact current detection device according to claim 6, characterized in that: Also includes one or more of the following: A LORA communication module, connected to the controller, for uploading the result of whether the controller determines whether there is current to a cloud server; The indication module is used to indicate the result of the controller determining whether there is current.

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