A power frequency current harmonic detection device and method based on linear TMR array

Abstract

The application provides a power frequency current harmonic detection device based on a linear TMR array, comprising a TMR sensor linear array structure, a preamplification circuit, a high-pass filter circuit, an AD conversion circuit, a power supply circuit and a single-chip microcomputer; the sensors in the TMR sensor linear array structure are each provided with a corresponding pulley to adjust the positions of the four sensors in the TMR sensor linear array structure; the TMR sensor linear array structure converts the input current into a voltage signal and inputs the voltage signal into the preamplification circuit; the preamplification circuit, the high-pass filter circuit and the AD conversion circuit process the analog signal, generate a digital signal and transmit the digital signal to the single-chip microcomputer; the single-chip microcomputer inversely calculates the to-be-measured power frequency current value and calculates the harmonic content of the to-be-measured power frequency current through a current harmonic detection algorithm of fast Fourier transform (FTT).

Description

Technical Field

[0001] This application relates to the field of power measurement technology, and in particular to a power frequency current harmonic detection device and method based on a linear TMR array. Background Technology

[0002] The rapid development of power electronics technology has led to the increasing presence of various nonlinear loads in people's production and daily lives, while also bringing significant harmonic pollution problems. In particular, the continuous introduction and promotion of smart substations in recent years has made modern power systems more complex, and the sources of harmonics have become more diversified. The generation of harmonic components in power systems is mainly due to the nonlinear loads generating non-standard sinusoidal currents under the action of a sinusoidal standard voltage, causing distortion of the current in the power grid. Harmonic frequencies are integer multiples of the fundamental frequency. According to the Fourier analysis principle, any repeating waveform can be decomposed into sinusoidal wave components containing the fundamental frequency and a series of harmonics that are multiples of the fundamental frequency. Harmonics are sinusoidal waves, and each harmonic has a different frequency, amplitude, and phase angle. Statistics show that the vast majority of the decline in power quality in power systems is due to the influence of harmonics. Therefore, the study of power grid harmonic problems has become a very important research task for researchers. In the process of harmonic mitigation, harmonic detection is the prerequisite and the most crucial element, because only by quickly and accurately detecting harmonics can a foundation be laid for subsequent harmonic mitigation.

[0003] Harmonic monitoring is divided into two methods: online monitoring and offline monitoring. Online monitoring generally uses monitoring instruments as the core, with a computer equipped with management software as the master station. Monitoring data is collected via wired or network connection, analyzed, and output in graphical form for analysis and use by relevant technicians. Offline monitoring uses portable testing instruments to periodically test suspected harmonic sources of interest. This method is lower in cost and offers greater convenience and efficiency. The demand for current harmonic detection in power systems is substantial. Online monitoring in all locations would be too costly and wasteful of resources. Therefore, research on portable current harmonic detection has significant theoretical and practical implications.

[0004] Currently, current harmonic detection based on magnetic sensors is mostly in the experimental research stage. Among them, TMR magnetic sensors have higher magnetoresistive strength and sensitivity, wider linear detection range, and lower noise figure and power consumption compared to other magnetic sensors. They can achieve non-contact detection and have great application value in portable current harmonic detection. Currently, most TMR current sensor arrays are ring-shaped. This method is beneficial for improving current detection accuracy, but the sensor needs to be passed through a cable and its relative position to the cable needs to be fixed during installation, which is inconvenient in practical use. Therefore, to ensure high accuracy and wide range for portable current harmonic detection while reducing the installation difficulty of routine inspections, this invention proposes a novel linear sensor array and detection method. Summary of the Invention

[0005] The purpose of this application is to solve the technical problem that conventional current harmonic detection technology cannot simultaneously achieve high precision and wide measurement range while reducing the installation difficulty of inspection, and to provide a power frequency current harmonic detection device and method based on a linear TMR array.

[0006] The above-mentioned objective of this application is achieved through the following technical solution: A power frequency current harmonic detection device based on a linear TMR array, comprising: The TMR sensor consists of a linear array structure, a preamplifier circuit, a high-pass filter circuit, an AD conversion circuit, a power supply circuit, and a microcontroller. The TMR sensor linear array structure, the preamplifier circuit, the high-pass filter circuit, the AD conversion circuit, and the microcontroller are all connected to the power supply circuit; the TMR sensor linear array structure and the high-pass filter circuit are all connected to the preamplifier circuit; the high-pass filter circuit and the microcontroller are all connected to the AD conversion circuit. The TMR sensor linear array structure includes: a TMR1 sensor, a TMR2 sensor, a TMR3 sensor, and a TMR4 sensor; the TMR1 sensor is located at the front end of the TMR sensor linear array structure, the TMR2 sensor is located after the TMR1 sensor, the TMR3 sensor is located after the TMR2 sensor, the TMR4 sensor is located after the TMR3 sensor, and the TMR4 sensor is located at the rear end of the TMR sensor linear array structure. Each of the TMR1, TMR2, TMR3, and TMR4 sensors is equipped with a corresponding pulley to adjust the position of the four sensors in the TMR sensor linear array structure. The types of TMR1 sensors include: single-axis sensors, dual-axis sensors, or tri-axis sensors; The magnetic sensing directions of the TMR2 sensor, the TMR3 sensor and the TMR4 sensor are the same and are all parallel to the direction of the current magnetic field; The range relationship of the four TMR sensors is set as follows: the range of the TMR1 sensor > the range of the TMR2 sensor > the range of the TMR3 sensor > the range of the TMR4 sensor; The accuracy relationship of the four TMR sensors is set as follows: the accuracy of the TMR1 sensor < the accuracy of the TMR2 sensor < the accuracy of the TMR3 sensor < the accuracy of the TMR4 sensor; The linear array structure of the TMR sensors is configured to convert the input current into a voltage signal and input the voltage signal to the preamplifier circuit; The preamplifier circuit is configured to amplify the input voltage signal and transmit it to the high-pass filter circuit; The high-pass filter circuit is configured to filter the amplified voltage signal and transmit it to the AD conversion circuit; The AD conversion circuit is configured to perform AD conversion on the filtered voltage signal, generate a digital signal and transmit the digital signal to the single-chip microcomputer; The single-chip microcomputer is configured to perform inversion calculation on the digital signal to obtain the power frequency current value to be measured and the harmonic content of each order of the power frequency current to be measured.

[0007] A method for detecting power frequency current harmonics based on a linear TMR array, wherein the TMR1 sensor is a single-axis sensor, and the method comprises: During measurement, manually adjust the front end of the linear array structure of the TMR sensors to be close to the conductor to be measured, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor to be measured; Adjust the linear array structure of the TMR sensors to the optimal measurement angle by manually correcting the position; observe the voltage reading on the x-axis , when the value is the minimum, that is the optimal measurement angle; fix the y-axis of the TMR1 sensor to be perpendicular to the conductor to be measured and the z-axis of the TMR1 sensor to be parallel to the conductor to be measured by an external tool; The linear array structure of the TMR sensors collects the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal, and generates a digital signal to be input into the single-chip microcomputer; The calculation formula for the magnetic flux density of the magnetic field excited by the current element at any point P in space is as follows: (1) (2) wherein, is the vacuum permeability, is the current magnitude, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The y-axis of the TMR1 sensor is parallel to the magnetic field; the magnetic field strength at the TMR2 sensor in the linear array structure of the TMR sensor Magnetic field strength at the TMR3 sensor and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor. These represent the distances of the TMR2, TMR3, and TMR4 sensors from the top of the TMR sensor linear array structure, respectively. The current measured by the TMR2 sensor The current measured by the TMR3 sensor and the current measured by the TMR4 sensor They are respectively: (5) Where G is the amplification factor of the preamplifier circuit. Indicates the sensitivity of the sensor. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

[0008] A method for detecting harmonics in power frequency current based on a linear TMR array, wherein the TMR1 sensor is a biaxial sensor, and the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; By fixing the xy-axis plane of the TMR1 sensor perpendicular to the conductor under test using external tools, the directional deviation of the x-axis is corrected, and the linear array structure of the TMR sensor is adjusted to the optimal measurement angle; the voltage reading on the x-axis is then observed. The size, when The optimal measurement angle is when the value of is minimized. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller; The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The z-axis of the TMR1 sensor is perpendicular to the direction of the current magnetic field; the x-axis of the TMR1 sensor is adjusted to be approximately perpendicular to the direction of the current magnetic field. Let the x-axis deviation angle of the TMR1 sensor be... The offset distance is , and The voltage readings are for the x-axis and y-axis, respectively. The x-axis deviation angle of the TMR2 sensor is [value missing]. ,have: (7) (8) (9) Magnetic field strength at the TMR2 sensor TMR3 sensor magnetic field strength at the location and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor; Current measured by the TMR2 sensor The current measured by the TMR3 sensor Current measured by TMR4 sensor They are respectively: (10) in, These represent the x-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively, where G is the amplification factor of the preamplifier circuit. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

[0009] A method for detecting harmonics in power frequency current based on a linear TMR array, wherein the TMR1 sensor is a triaxial sensor, and the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; If the TMR1 sensor is a triaxial sensor, no external tools are needed. Manually adjust the x and y axis planes to be perpendicular to the conductor under test, and correct the offset directions of the TMR1 sensor's x, y, and z axes; adjust the linear array structure of the TMR sensor to the optimal measurement angle; observe the voltage reading on the x-axis. The size, when The optimal measurement angle is when the value of is minimized. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters, and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller. The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The x and z axes of the TMR1 sensor are approximately perpendicular to the direction of the current magnetic field. Let the x-axis deviation angle of the TMR1 sensor be... The offset distance is , and The voltage readings are for the x-axis and y-axis, respectively. The x-axis deviation angle of the TMR2 sensor is [value missing]. ,have: (7) (8) (9) Magnetic field strength at the TMR2 sensor TMR3 sensor magnetic field strength at the location and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor; The current measured by the TMR2 sensor The current measured by the TMR3 sensor Current measured by TMR4 sensor They are respectively: (11) in, These represent the z-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively, with G being the amplification factor of the preamplifier circuit. These are the x-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

[0010] The beneficial effects of the technical solution provided in this application are: A power frequency current harmonic detection device based on a linear TMR array is provided, including a TMR sensor linear array structure, a preamplifier circuit, a high-pass filter circuit, an AD conversion circuit, a power supply circuit, and a microcontroller. The TMR1 sensor in the TMR sensor linear array structure is used to correct the position of the TMR sensor linear array structure and can be configured as a single-axis, dual-axis, or triaxial sensor to provide three measurement modes to adapt to different scenario requirements. The TMR2, TMR3, and TMR4 sensors in the TMR sensor linear array structure are high-precision sensors used to measure current. The position of the sensors on the TMR sensor linear array structure is determined according to the accuracy and range relationships of each sensor. Four pulleys are set on the TMR sensor linear array structure to adjust the position of the four TMR sensors, which facilitates improved measurement accuracy. The linear array structure design of the TMR sensors reduces the difficulty of installation and use during inspection, and the use of multiple sensor fusion technology achieves high-precision and wide-range detection. Attached Figure Description

[0011] The present application will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a circuit diagram of the power frequency current harmonic detection device of the linear TMR array in the embodiments of this application; Figure 2This is a structural diagram of the linear TMR sensor linear array of the power frequency current harmonic detection device in the embodiments of this application; Figure 3 This is a power circuit diagram of the power frequency current harmonic detection device of the linear TMR array in the embodiments of this application; Figure 4 This is a preamplifier circuit diagram of the power frequency current harmonic detection device of the linear TMR array in the embodiments of this application; Figure 5 This is a schematic diagram of the current and magnetic field distribution of the power frequency current harmonic detection device of the linear TMR array in the embodiments of this application; Figure 6 This is a measurement equivalent schematic diagram of the power frequency current harmonic detection device of the linear TMR array in the embodiments of this application. Detailed Implementation

[0012] To provide a clearer understanding of the technical features, objectives, and effects of this application, the specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0013] The embodiments of this application provide a power frequency current harmonic detection device and method based on a linear TMR array.

[0014] Please refer to Figure 1 , Figure 1 This is a circuit diagram of a power frequency current harmonic detection method based on a linear TMR array according to an embodiment of this application, specifically including the following: The TMR sensor consists of a linear array structure, a preamplifier circuit, a high-pass filter circuit, an AD conversion circuit, a power supply circuit, and a microcontroller. The TMR sensor linear array structure, the preamplifier circuit, the high-pass filter circuit, the AD conversion circuit, and the microcontroller are all connected to the power supply circuit; the TMR sensor linear array structure and the high-pass filter circuit are all connected to the preamplifier circuit; the high-pass filter circuit and the microcontroller are all connected to the AD conversion circuit. The TMR sensor linear array structure includes: a TMR1 sensor, a TMR2 sensor, a TMR3 sensor, and a TMR4 sensor; the TMR1 sensor is located at the front end of the TMR sensor linear array structure, the TMR2 sensor is located after the TMR1 sensor, the TMR3 sensor is located after the TMR2 sensor, the TMR4 sensor is located after the TMR3 sensor, and the TMR4 sensor is located at the rear end of the TMR sensor linear array structure. Each of the TMR1 sensor, the TMR2 sensor, the TMR3 sensor and the TMR4 sensor is provided with a corresponding pulley to adjust the positions of the four sensors in the linear array structure of TMR sensors; The type of the TMR1 sensor includes: a uniaxial sensor, a biaxial sensor or a triaxial sensor; The magnetosensitive directions of the TMR2 sensor, the TMR3 sensor and the TMR4 sensor are the same and are all parallel to the direction of the current magnetic field; The range relationship of the four TMR sensors is set as follows: the range of the TMR1 sensor > the range of the TMR2 sensor > the range of the TMR3 sensor > the range of the TMR4 sensor; The accuracy relationship of the four TMR sensors is set as follows: the accuracy of the TMR1 sensor < the accuracy of the TMR2 sensor < the accuracy of the TMR3 sensor < the accuracy of the TMR4 sensor; The linear array structure of TMR sensors is used for converting an input current into a voltage signal, and outputting the voltage signal to the preamplifier circuit; The preamplifier circuit is used for amplifying the input voltage signal and transmitting the amplified voltage signal to the high-pass filter circuit; The high-pass filter circuit is used for filtering the amplified voltage signal and transmitting the filtered voltage signal to the AD conversion circuit; The AD conversion circuit is used for performing AD conversion on the filtered voltage signal to generate a digital signal and transmitting the digital signal to the single-chip microcomputer; The single-chip microcomputer is used for performing inversion calculation on the digital signal to obtain the power frequency current value to be measured and the harmonic content of each order of the power frequency current to be measured.

[0015] Optionally, the power supply circuit includes: an integrated chip U5, an integrated chip U6, an integrated chip U8, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, and a resistor R1; Pin 1 of integrated chip U8 is connected to pin 2 of integrated chip U8, pin 5 of integrated chip U5, one end of capacitor C1, and one end of capacitor C3, simultaneously outputting voltage V1. Pin 3 of integrated chip U8 is grounded. Pin 4 of integrated chip U8 is connected to the other end of capacitor C1; the other end of capacitor C3 is grounded. Pin 5 of integrated chip U8 is connected to pin 8 of integrated chip U8, one end of capacitor C2, and power supply Vcc; the other end of capacitor C2 is grounded. Pin 6 of integrated chip U8 is connected to pin 7 of integrated chip U8. Ground; pin 1 of integrated chip U5 outputs V2 voltage, pins 2 and 3 of integrated chip U5 are both grounded, and pin 4 of integrated chip U5 is unused; pin 1 of integrated chip U6 is connected to power supply Vcc, pin 2 of integrated chip U6 is grounded, and pin 4 of integrated chip U6 is connected to one end of capacitor C4; the other end of capacitor C4 is connected to pin 6 of integrated chip U6; resistor R1 is connected in parallel with capacitor C4; pin 4 of integrated chip U6 outputs V4 voltage, and pin 6 of integrated chip U6 outputs V5 voltage.

[0016] Optionally, the preamplifier circuit includes: capacitor C19, capacitor C20, resistor R8, and integrated chip U8A; The resistor R8 is a precision resistor; Pin 1 of the integrated chip U8A is connected to one end of resistor R8, and the other end of resistor R8 is connected to pin 8 of the integrated chip U8A. Pins 2 and 3 of the integrated chip U8A are connected to the negative and positive input terminals of the signal, respectively. Pin 4 of the integrated chip U8A is connected to one end of capacitor C20, and the other end of capacitor C20 is grounded. Pin 4 of the integrated chip U8A is connected to the V2 voltage output terminal. Pin 5 of the integrated chip U8A is grounded. Pin 6 of the integrated chip U8A outputs the amplified voltage signal. Pin 7 of U8A is connected to one end of capacitor C19 and the V1 voltage output terminal, and the other end of capacitor C19 is grounded. The preamplifier circuit converts the differential voltage signal output by TMR into a single-ended voltage signal.

[0017] A method for detecting harmonics in power frequency current based on a linear TMR array, wherein the TMR1 sensor is a single-axis sensor, and the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; The TMR sensor linear array structure was manually adjusted to the optimal measurement angle; the voltage readings on the x-axis were then observed. The size, when The optimal measurement angle is when the value is at its minimum. The y-axis of the TMR1 sensor is fixed perpendicular to the conductor under test by external tools, and the z-axis of the TMR1 sensor is parallel to the conductor under test. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller; The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The y-axis of the TMR1 sensor is parallel to the magnetic field; the magnetic field strength at the TMR2 sensor in the linear array structure of the TMR sensor is... Magnetic field strength at the TMR3 sensor and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor. These represent the distances of the TMR2, TMR3, and TMR4 sensors from the top of the TMR sensor linear array structure, respectively. The current measured by the TMR2 sensor The current measured by the TMR3 sensor and the current measured by the TMR4 sensor They are respectively: (5) Where G is the amplification factor of the preamplifier circuit. Indicates the sensitivity of the sensor. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

[0018] A method for detecting harmonics in power frequency current based on a linear TMR array, wherein the TMR1 sensor is a biaxial sensor, and the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; By fixing the xy-axis plane of the TMR1 sensor perpendicular to the conductor under test using external tools, the directional deviation of the x-axis is corrected, and the linear array structure of the TMR sensor is adjusted to the optimal measurement angle; the voltage reading on the x-axis is then observed. The size, when The optimal measurement angle is when the value of is minimized. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller; The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The z-axis of the TMR1 sensor is perpendicular to the direction of the current magnetic field; the x-axis of the TMR1 sensor is adjusted to be approximately perpendicular to the direction of the current magnetic field. Let the x-axis deviation angle of the TMR1 sensor be... The offset distance is , and The voltage readings are for the x-axis and y-axis, respectively. The x-axis deviation angle of the TMR2 sensor is [value missing]. ,have: (7) (8) (9) Magnetic field strength at the TMR2 sensor Magnetic field strength at the TMR3 sensor and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor; Current measured by the TMR2 sensor The current measured by the TMR3 sensor The current measured by the TMR4 sensor They are respectively: (10) in, These represent the x-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively, where G is the amplification factor of the preamplifier circuit. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

[0019] A method for detecting harmonics in power frequency current based on a linear TMR array, wherein the TMR1 sensor is a triaxial sensor, and the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; If the TMR1 sensor is a triaxial sensor, no external tools are needed. Manually adjust the x and y axis planes to be perpendicular to the conductor under test, and correct the offset directions of the TMR1 sensor's x, y, and z axes; adjust the linear array structure of the TMR sensor to the optimal measurement angle; observe the voltage reading on the x-axis. The size, when The optimal measurement angle is when the value of is minimized. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller; The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The x and z axes of the TMR1 sensor are approximately perpendicular to the direction of the current magnetic field. Let the x-axis deviation angle of the TMR1 sensor be... The offset distance is , and The voltage readings are for the x-axis and y-axis, respectively. The x-axis deviation angle of the TMR2 sensor is [value missing]. ,have: (7) (8) (9) Magnetic field strength at the TMR2 sensor TMR3 sensor magnetic field strength at the location and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor; The current measured by the TMR2 sensor The current measured by the TMR3 sensor The current measured by the TMR4 sensor They are respectively: (11) in, These represent the z-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively, with G being the amplification factor of the preamplifier circuit. These are the x-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

[0020] In this application, integrated chip U8 can be LT1763, integrated chip U5 can be LM7905, integrated chip U6 can be B1205S-2W, and integrated chip U8A can be INA128.

[0021] Specifically, when the power frequency current to be measured is large, the magnetic field generated will saturate the TMR. The pulley can be adjusted to move the TMR away from the conductor to be measured, so that the magnitude of the magnetic field in the space is within the range that the TMR can measure. Specifically, external tools can be: right-angle calipers, right-angle clips, right-angle calipers, etc.

[0022] Specifically, the four sensors have different functions. TMR1 is used for position correction. Because it is located at the front, it needs to be a sensor with a large range of measurable magnetic fields, but the requirements for accuracy and sensitivity are not high.

[0023] Specifically, the AD conversion circuit is a multi-channel synchronous high-speed AD conversion circuit; TMR2, TMR3, and TMR4 are used for precise measurements. Depending on the location, from near to far, the measurable magnetic field range gradually decreases while the sensitivity gradually increases. Furthermore, through adjustable distance, the position correction algorithm performed by TMR1, and the integration of data from the three sensors, the measurement range of this sensor array is improved while maintaining a certain level of accuracy.

[0024] Specifically, such as Figure 5 The distribution of the current and magnetic field shows that when the magnetic induction direction of the TMR1 sensor is perpendicular to the conductor under test and points towards the center line of the conductor, the three sensors at the rear end of the TMR sensor linear array structure will have a strong magnetic field signal. Analysis of the TMR1 sensor... Current value, when When the value is at its minimum, the voltage reading on the x-axis The minimum value is the optimal measurement angle. In actual measurements, this method is used to correct the position of the linear array structure of the TMR sensor.

[0025] The following is a specific embodiment of the present invention: This paper designs a TMR current harmonic detection system, focusing on a relatively large current range of 0-200A. Taking the TMR1 sensor as a single-axis chip, the TMR2083 chip is selected, with a saturation magnetic field of ±1000 Gs and a sensitivity of 0.2 mV / V / Gs. For TMR2, the TMR2009 is selected, with a saturation magnetic field of ±200 Gs and a sensitivity of 0.3 mV / V / Gs. For TMR3, the TMR2104 is selected, with a saturation magnetic field of ±150 Gs and a sensitivity of 3.1 mV / V / Gs. For TMR4, the TMR2103 is selected, with a saturation magnetic field of ±75 Gs and a sensitivity of 6 mV / V / Gs. The detectable magnetic field range and sensitivity of the sensors gradually increase, and a sensor fusion algorithm is used to achieve a wide range and high accuracy.

[0026] In the power supply circuit, the entire system is powered by a +12V lithium battery. Integrated chip U8 uses an LT1763, with capacitors C1 (0.01μF), C2 (1μF), and C3 (10μF), providing a +5V output at V1. Integrated chip U5 uses an LM7905 to step down the voltage to V2, providing a -5V output. Integrated chip U6 uses a B1205S-2W, with capacitor C4 (4.7μF) and resistor R1 (125Ω), providing a 5V output at V4 and a 0V output at V5. In the amplifier circuit, U8A uses an instrumentation amplifier chip, INA128, with a 505Ω precision resistor R8, resulting in a 100x amplification factor. Capacitors C20 and C19 are 0.1μF, and the supply voltage is ±5V. The filtering circuit uses an active filter to remove DC and low-frequency voltages below 40Hz. The AD sampling circuit uses the AD7606, which provides 8-channel synchronous acquisition, 16-bit AD conversion, and a 200kSPS sampling rate. Finally, the sampled voltage signal is processed by a fusion algorithm in the embedded system and harmonic analysis is performed, which can accurately detect the amplitude and content of harmonics up to the 20th order.

[0027] The above are merely exemplary embodiments of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Other embodiments of this disclosure will be readily apparent to those skilled in the art upon consideration of the disclosure herein.

[0028] This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described in this disclosure. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. A power frequency current harmonic detection device based on a linear TMR array, characterized in that, comprising: a TMR sensor linear array structure, a pre-amplification circuit, a high-pass filter circuit, an AD conversion circuit, a power supply circuit, and a single-chip microcomputer; The TMR sensor linear array structure, the pre-amplification circuit, the high-pass filter circuit, the AD conversion circuit and the single-chip microcomputer are all connected to the power supply circuit; the TMR sensor linear array structure and the high-pass filter circuit are both connected to the pre-amplification circuit; the high-pass filter circuit and the single-chip microcomputer are both connected to the AD conversion circuit; The TMR sensor linear array structure comprises: a TMR1 sensor, a TMR2 sensor, a TMR3 sensor and a TMR4 sensor; the TMR1 sensor is arranged at the front end of the TMR sensor linear array structure, the TMR2 sensor is arranged behind the TMR1 sensor, the TMR3 sensor is arranged behind the TMR2 sensor, the TMR4 sensor is arranged behind the TMR3 sensor, and the TMR4 sensor is arranged at the rear end of the TMR sensor linear array structure; The TMR1 sensor, the TMR2 sensor, the TMR3 sensor and the TMR4 sensor are each provided with a corresponding pulley to adjust the positions of the four sensors in the TMR sensor linear array structure; The type of the TMR1 sensor comprises: a uniaxial sensor, a biaxial sensor or a triaxial sensor; The magnetic sensing directions of the TMR2 sensor, the TMR3 sensor and the TMR4 sensor are the same and are all parallel to the direction of the current magnetic field; The range relationship of the four TMR sensors is set as follows: the range of the TMR1 sensor > the range of the TMR2 sensor > the range of the TMR3 sensor > the range of the TMR4 sensor; The accuracy relationship of the four TMR sensors is set as follows: the accuracy of the TMR1 sensor < the accuracy of the TMR2 sensor < the accuracy of the TMR3 sensor < the accuracy of the TMR4 sensor; The TMR sensor linear array structure is configured to convert an input current into a voltage signal and input the voltage signal to the pre-amplification circuit; The pre-amplification circuit is configured to amplify the input voltage signal and transmit the amplified voltage signal to the high-pass filter circuit; The high-pass filter circuit is configured to filter the amplified voltage signal and transmit the filtered voltage signal to the AD conversion circuit; The AD conversion circuit is configured to perform AD conversion on the filtered voltage signal, generate a digital signal and transmit the digital signal to the single-chip microcomputer; The single-chip microcomputer is configured to perform inversion calculation on the digital signal to obtain the value of the power frequency current to be measured and the harmonic content of each order of the power frequency current to be measured.

2. The power frequency current harmonic detection device based on a linear TMR array as described in claim 1, characterized in that, The power supply circuit comprises: an integrated chip U5, an integrated chip U6, an integrated chip U8, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, and a resistor R1; Pin 1 of integrated chip U8 is connected to pin 2 of integrated chip U8, pin 5 of integrated chip U5, one end of capacitor C1, and one end of capacitor C3, simultaneously outputting voltage V1. Pin 3 of integrated chip U8 is grounded. Pin 4 of integrated chip U8 is connected to the other end of capacitor C1; the other end of capacitor C3 is grounded. Pin 5 of integrated chip U8 is connected to pin 8 of integrated chip U8, one end of capacitor C2, and power supply Vcc; the other end of capacitor C2 is grounded. Pin 6 of integrated chip U8 is connected to pin 7 of integrated chip U8. Ground; pin 1 of integrated chip U5 outputs V2 voltage, pins 2 and 3 of integrated chip U5 are both grounded, and pin 4 of integrated chip U5 is unused; pin 1 of integrated chip U6 is connected to power supply Vcc, pin 2 of integrated chip U6 is grounded, and pin 4 of integrated chip U6 is connected to one end of capacitor C4; the other end of capacitor C4 is connected to pin 6 of integrated chip U6; resistor R1 is connected in parallel with capacitor C4; pin 4 of integrated chip U6 outputs V4 voltage, and pin 6 of integrated chip U6 outputs V5 voltage.

3. The power frequency current harmonic detection device based on a linear TMR array as described in claim 1, characterized in that, The preamplifier circuit includes: capacitor C19, capacitor C20, resistor R8, and integrated chip U8A; The resistor R8 is a precision resistor; Pin 1 of the integrated chip U8A is connected to one end of resistor R8, and the other end of resistor R8 is connected to pin 8 of the integrated chip U8A. Pins 2 and 3 of the integrated chip U8A are connected to the negative and positive input terminals of the signal, respectively. Pin 4 of the integrated chip U8A is connected to one end of capacitor C20, and the other end of capacitor C20 is grounded. Pin 4 of the integrated chip U8A is connected to the V2 voltage output terminal. Pin 5 of the integrated chip U8A is grounded. Pin 6 of the integrated chip U8A outputs the amplified voltage signal. Pin 7 of U8A is connected to one end of capacitor C19 and the V1 voltage output terminal, and the other end of capacitor C19 is grounded. The preamplifier circuit converts the differential voltage signal output by TMR into a single-ended voltage signal.

4. A method for detecting harmonics in power frequency current based on a linear TMR array, characterized in that, Using the apparatus as described in any one of claims 1-3, wherein the TMR1 sensor is a single-axis sensor, the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure as described in claim 1 to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; The TMR sensor linear array structure was manually adjusted to the optimal measurement angle; the voltage reading on the x-axis was then observed. The size, when The optimal measurement angle is when the value is at its minimum. The y-axis of the TMR1 sensor is fixed perpendicular to the conductor under test by external tools, and the z-axis of the TMR1 sensor is parallel to the conductor under test. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller; The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The y-axis of the TMR1 sensor is parallel to the magnetic field; the magnetic field strength at the TMR2 sensor in the linear array structure of the TMR sensor is... Magnetic field strength at the TMR3 sensor and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor. These represent the distances of the TMR2, TMR3, and TMR4 sensors from the top of the TMR sensor linear array structure, respectively. The current measured by the TMR2 sensor The current measured by the TMR3 sensor and the current measured by the TMR4 sensor They are respectively: (5) Where G is the amplification factor of the preamplifier circuit. Indicates the sensitivity of the sensor. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

5. A method for detecting harmonics in power frequency current based on a linear TMR array, characterized in that, Using the apparatus as described in any one of claims 1-3, wherein the TMR1 sensor is a biaxial sensor, the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure as described in claim 1 to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; By fixing the xy-axis plane of the TMR1 sensor perpendicular to the conductor under test using external tools, the directional deviation of the x-axis is corrected, and the linear array structure of the TMR sensor is adjusted to the optimal measurement angle; the voltage reading on the x-axis is then observed. The size, when The optimal measurement angle is when the value of is minimized. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller; The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The z-axis of the TMR1 sensor is perpendicular to the direction of the current magnetic field; the x-axis of the TMR1 sensor is adjusted to be approximately perpendicular to the direction of the current magnetic field. Let the x-axis deviation angle of the TMR1 sensor be... The offset distance is , and The voltage readings are for the x-axis and y-axis, respectively. The x-axis deviation angle of the TMR2 sensor is [value missing]. ,have: (7) (8) (9) Magnetic field strength at the TMR2 sensor Magnetic field strength at the TMR3 sensor and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor; Current measured by the TMR2 sensor The current measured by the TMR3 sensor The current measured by the TMR4 sensor They are respectively: (10) in, These represent the x-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively, where G is the amplification factor of the preamplifier circuit. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

6. A method for detecting harmonics in power frequency current based on a linear TMR array, characterized in that, Using the apparatus as described in any one of claims 1-3, wherein the TMR1 sensor is a triaxial sensor, the method includes: During measurement, manually adjust the front end of the TMR sensor linear array structure as described in claim 1 to be close to the conductor under test, and adjust the x-axis direction of the TMR1 sensor to be perpendicular to the center of the conductor under test; If the TMR1 sensor is a triaxial sensor, no external tools are needed. Manually adjust the x and y axis planes to be perpendicular to the conductor under test, and correct the offset directions of the TMR1 sensor's x, y, and z axes; adjust the linear array structure of the TMR sensor to the optimal measurement angle; observe the voltage reading on the x-axis. The size, when The optimal measurement angle is when the value of is minimized. The TMR sensor linear array structure acquires the voltage signal of the power frequency current to be measured, amplifies, filters and performs AD conversion on the voltage signal to generate a digital signal that is input to the microcontroller; The formula for calculating the magnetic induction intensity of the magnetic field generated by a current element at any point P in space is as follows: (1) (2) in, The permeability of free space, For the magnitude of the current, For the integration path, It is a tiny line element of the current element. Let be the unit vector pointing from the current element to the point of the field to be determined; This represents the distance vector from the current element to point P. Let P be the distance from the current element to point P. for and Angle; The x and z axes of the TMR1 sensor are approximately perpendicular to the direction of the current magnetic field. Let the x-axis deviation angle of the TMR1 sensor be... The offset distance is , and The voltage readings are for the x-axis and y-axis, respectively. The x-axis deviation angle of the TMR2 sensor is [value missing]. ,have: (7) (8) (9) Magnetic field strength at the TMR2 sensor Magnetic field strength at the TMR3 sensor and the magnetic field strength at the TMR4 sensor They are respectively: (3) The formulas for calculating the output voltage and applied magnetic field strength of the TMR sensor linear array structure are as follows: (4) in, The magnetic flux density of the sensor, The sensitivity of the sensor; The power supply voltage for each sensor; The current measured by the TMR2 sensor The current measured by the TMR3 sensor The current measured by the TMR4 sensor They are respectively: (11) in, These represent the z-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively, with G being the amplification factor of the preamplifier circuit. These are the x-axis deviation angles of the TMR2, TMR3, and TMR4 sensors, respectively. These represent the output voltage values ​​of the TMR2, TMR3, and TMR4 sensors, respectively. According to the Biot-Savart theorem, the digital signal is inverted, and the inverted measured current value is: (6) The current The fundamental frequency and harmonic content of the power frequency current under test are calculated by using the Fast Fourier Transform (FFT) algorithm in the microcontroller.

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