Primary current measurement system of electromagnetic voltage transformer based on GMR sensor

Abstract

The present invention discloses a primary current measurement system for an electromagnetic voltage transformer based on a GMR sensor, which relates to the technical field of power system monitoring. It includes a composite magnetic circuit module, which realizes magnetic flux separation through a conical ferrite magnetic ring, a main magnetic circuit and an auxiliary magnetic circuit, conducts the power frequency magnetic flux to the iron core, and conducts the high-frequency magnetic flux to the GMR sensor array. The GMR sensor array adopts an orthogonal dual sensor combined with a ring distribution and is equipped with a differential output channel to effectively eliminate position deviation. The signal processing module integrates a preamplifier, an analog-to-digital converter, a dual-frequency bandpass filter and an embedded processor, executes an adaptive Kalman filter algorithm, and improves signal processing accuracy. The system also has insulation shielding, reliability assurance and temperature compensation modules, which respectively provide electromagnetic shielding, hardware monitoring, dual power supply redundancy and ambient temperature compensation functions to ensure the safe and stable operation of the measurement system. The present invention is suitable for current measurement in power systems and has significant technical advantages and practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of power system monitoring, and in particular relates to a primary current measurement system of an electromagnetic voltage transformer based on a GMR sensor. Background Art

[0002] During the operation and monitoring of power systems, accurate detection of parameters such as current and magnetic fields is crucial for ensuring safe and stable system operation. Traditional detection technologies have numerous shortcomings, including suboptimal magnetic circuit design, resulting in low magnetic field detection sensitivity; weak signal processing system anti-interference capabilities, which affect detection accuracy; and poor high-voltage insulation performance, which can easily lead to safety incidents. Furthermore, the lack of effective calibration mechanisms and modular design hinders equipment maintenance and upgrades. The development of smart grids places higher demands on the accuracy and stability of current measurement. GMR sensors, due to their high sensitivity, low power consumption, and ease of integration, show great potential in current measurement. However, effectively utilizing GMR sensors to build high-performance current measurement systems, particularly achieving accurate measurements in complex electromagnetic environments, remains a hot topic and a challenge. Summary of the Invention

[0003] The present invention proposes a primary current measurement system for an electromagnetic voltage transformer based on a GMR sensor. The system achieves high-precision and high-stability current measurement by optimizing the magnetic circuit design, adopting advanced signal processing algorithms, and integrating multiple reliability assurance measures.

[0004] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0005] The present invention is a primary current measurement system for an electromagnetic voltage transformer based on a GMR sensor, comprising:

[0006] A composite magnetic circuit module includes a conical ferrite magnetic concentrator, a main magnetic circuit, and an auxiliary magnetic circuit. The conical ferrite magnetic concentrator, the main magnetic circuit, and the auxiliary magnetic circuit form a magnetic flux separation structure. The main magnetic circuit is configured to conduct power frequency magnetic flux to the iron core, and the auxiliary magnetic circuit is configured to conduct high frequency magnetic flux to the GMR sensor array. The auxiliary magnetic circuit includes a spiral magnetic focuser. The main and auxiliary magnetic circuits are coupled via a non-contact air gap to form a closed magnetic flux loop.

[0007] The GMR sensor array module is arranged in the non-saturated area of ​​the annular core of the auxiliary magnetic circuit, adopts a combination of an orthogonal dual sensor array and an annular distribution, and is equipped with a differential output channel to eliminate position deviation;

[0008] a signal processing module comprising a preamplifier, an analog-to-digital converter, a dual-frequency bandpass filter, and an embedded processor connected in sequence, wherein the embedded processor is configured to execute an adaptive Kalman filter algorithm;

[0009] The insulation shielding module includes a three-layer electromagnetic shielding system and a partial discharge monitoring module. The three-layer electromagnetic shielding system is composed of a magnetic conductive layer, a shielding layer, and a protective layer from the inside to the outside.

[0010] Reliability assurance module, integrating partial discharge monitoring unit, hardware watchdog circuit and dual power supply redundancy system;

[0011] Temperature compensation module, including PT100 thin film temperature sensor and EEPROM memory.

[0012] As a preferred technical solution of the present invention, a modular architecture is also included, which includes:

[0013] Standardized interface components, supporting DIN rail and PCB stamp hole connection;

[0014] The hot-swappable connector supports the live replacement of the sensor array, signal processing board and shielding structure. As a preferred technical solution of the present invention, in the composite magnetic circuit structure:

[0015] The air gap height between the conical ferrite magnetic focusing ring of the main magnetic circuit and the spiral magnetic focuser of the auxiliary magnetic circuit is 0.1-0.3 mm, and a nano-ceramic insulating layer is provided in the air gap area.

[0016] As a preferred technical solution of the present invention, the spiral magnetic concentrator is made of Permalloy material with a magnetic permeability of >100,000, a spiral angle designed to be 35°±1°, a 2μm thick insulating coating on the surface, and a distance from the GMR sensor controlled in the range of 0.5-1.5mm.

[0017] As a preferred technical solution of the present invention, in the GMR sensor array module:

[0018] The orthogonal dual sensor group is arranged at 90 degrees orthogonally, with an axial spacing of 2mm, and is distributed in an annular manner on the inner wall of the conical magnetic ring;

[0019] The differential output channel connects the output ends of the two sets of sensors to eliminate the magnetic field detection error caused by sensor position deviation;

[0020] The single-ended output channel is connected to the temperature compensation module to achieve synchronous acquisition of multi-physics field coupled signals.

[0021] As a preferred technical solution of the present invention, the adaptive Kalman filtering algorithm of the signal processing module includes:

[0022] Temperature drift compensation function, based on the temperature-magnetic field coupling model established by finite element analysis;

[0023] Stress correction model, satisfying

[0024] H correction =α·ε+β·dε / dt

[0025] Among them, α=0.15±0.02, β=0.08±0.01;

[0026] Dynamic noise covariance matrix update module, with an update frequency of 1kHz±10%.

[0027] As a preferred technical solution of the present invention, the dual-frequency bandpass filter satisfies:

[0028] Main frequency channel: center frequency 10kHz±50Hz, stopband attenuation ≥80dB@1MHz;

[0029] Auxiliary frequency channel: center frequency 100kHz±20kHz, quality factor Q≥50;

[0030] Adopting cascaded elliptical filter topology, the group delay fluctuation is ≤5ns.

[0031] As a preferred technical solution of the present invention, the partial discharge monitoring module is connected to the main insulation layer through a capacitive coupling electrode, includes a high-frequency current sensor and an ultra-high frequency antenna array, and uses a wavelet packet decomposition algorithm to extract discharge characteristics in the 0.1-30MHz frequency band.

[0032] As a preferred technical solution of the present invention, in the temperature compensation module:

[0033] The PT100 thin film temperature sensor is embedded 1mm below the sensor substrate to establish a temperature-sensitivity compensation model:

[0034] S(T)=S0·[1+α(T-T0)+β(T-T0) 2 ]

[0035] The EEPROM memory calls the compensation coefficients in a 100ms cycle to execute the finite element temperature field correction algorithm.

[0036] The present invention has the following beneficial effects:

[0037] High-precision measurement: Magnetic flux separation is achieved through the composite magnetic circuit module, and the GMR sensor array module is used to accurately detect high-frequency magnetic flux. Combined with the adaptive Kalman filter algorithm and dual-frequency bandpass filter of the signal processing module, measurement accuracy is effectively improved.

[0038] Strong anti-interference capability: The three-layer electromagnetic shielding system of the insulation shielding module and the partial discharge monitoring module can effectively shield external electromagnetic interference, monitor the insulation status in real time, and improve the system's anti-interference capability and reliability.

[0039] High reliability and stability: The reliability assurance module's partial discharge monitoring unit, hardware watchdog circuit, and dual power redundancy system, as well as the temperature compensation function of the temperature compensation module, ensure the system's stable operation under various environmental conditions.

[0040] Good maintainability and flexibility: The standardized interface components and hot-swappable connectors of the modular architecture facilitate system installation, integration and maintenance, improving the system's maintainability and flexibility.

[0041] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 This is an architecture diagram of the system in the present invention;

[0044] Figure 2 This is a schematic diagram of the composite magnetic circuit air gap coupling principle in the present invention;

[0045] Figure 3 Schematic diagram of the GMR sensor array module of the present invention;

[0046] Figure 4 Schematic diagram of the interior of the composite magnetic circuit module of the present invention;

[0047] Figure 5 This is a flow chart of signal processing in the present invention. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] See also Figure 1-5As shown, the present invention discloses an electromagnetic voltage transformer primary current measurement system based on a GMR sensor, comprising:

[0050] A composite magnetic circuit module comprises a conical ferrite magnetic concentrator, a main magnetic circuit, and an auxiliary magnetic circuit, wherein the conical ferrite magnetic concentrator, the main magnetic circuit, and the auxiliary magnetic circuit form a magnetic flux separation structure, wherein the main magnetic circuit is configured to conduct power frequency magnetic flux to the iron core, and the auxiliary magnetic circuit is configured to conduct high frequency magnetic flux to the GMR sensor array, and the auxiliary magnetic circuit includes a spiral magnetic focuser, and the main magnetic circuit and the auxiliary magnetic circuit are coupled via a non-contact air gap to form a closed magnetic flux loop;

[0051] The GMR sensor array module is arranged in the non-saturated area of ​​the annular core of the auxiliary magnetic circuit, adopts a combination of an orthogonal dual sensor array and an annular distribution, and is equipped with a differential output channel to eliminate position deviation;

[0052] a signal processing module comprising a preamplifier, an analog-to-digital converter, a dual-frequency bandpass filter, and an embedded processor connected in sequence, wherein the embedded processor is configured to execute an adaptive Kalman filter algorithm;

[0053] The insulation shielding module includes a three-layer electromagnetic shielding system and a partial discharge monitoring module. The three-layer electromagnetic shielding system is composed of a magnetic conductive layer, a shielding layer, and a protective layer from the inside to the outside.

[0054] Reliability assurance module, integrating partial discharge monitoring unit, hardware watchdog circuit and dual power supply redundancy system;

[0055] Temperature compensation module, including PT100 thin film temperature sensor and EEPROM memory.

[0056] This embodiment uses a composite magnetic circuit module to achieve magnetic flux separation and conduction, and utilizes a GMR sensor array module for high-precision measurement. The signal processing module adopts an adaptive Kalman filter algorithm to improve the accuracy and stability of signal processing. The insulation shielding module and the reliability assurance module provide electromagnetic shielding and reliability assurance to ensure safe and stable operation of the system. The temperature compensation module further improves the accuracy of the measurement system by measuring the ambient temperature and performing compensation.

[0057] The present invention is specifically implemented as follows:

[0058] (1) Implementation of composite magnetic circuit module

[0059] 1. Select a suitable conical ferrite magnetic concentrator, and design its material and size according to the actual measurement requirements. Install the conical ferrite magnetic concentrator at a suitable position in the main magnetic circuit, ensuring that it fits tightly with the iron core of the main magnetic circuit to effectively conduct the power frequency magnetic flux.

[0060] 2. The spiral magnetic focuser in the auxiliary magnetic circuit is made of Permalloy, using precision machining to ensure a helix angle of 35°±1°. A 2μm-thick insulating coating is applied to its surface. The spiral magnetic focuser is installed in the auxiliary magnetic circuit, maintaining an air gap of 0.1-0.3mm between it and the conical ferrite magnetic focusing ring. A nano-ceramic insulating material is applied to the air gap to form a nano-ceramic insulating layer.

[0061] 3. Adjust the positions of the main magnetic circuit and the auxiliary magnetic circuit so that they form a closed magnetic flux circuit through non-contact air gap coupling, ensuring that the power frequency magnetic flux and high frequency magnetic flux can be effectively conducted along the main magnetic circuit and the auxiliary magnetic circuit respectively.

[0062] (2) Implementation of GMR sensor array module

[0063] 1. Arrange the orthogonal dual sensor group at 90°, ensuring an axial spacing of 2mm, and then distribute them in a ring at appropriate positions on the inner wall of the conical magnetic focusing ring, ensuring that the sensors are located in the non-saturated area of ​​the annular iron core of the auxiliary magnetic circuit.

[0064] 2. Connect the differential output channel and the single-ended output channel. Connect the differential output channel to the output terminals of the two sets of sensors. Through circuit design, the magnetic field detection error caused by sensor position deviation can be eliminated. Connect the single-ended output channel to the temperature compensation module to achieve synchronous acquisition of multi-physics field coupling signals.

[0065] (3) Implementation of signal processing module

[0066] 1. Select a suitable preamplifier and set the preamplifier's gain, bandwidth and other parameters according to the characteristics of the GMR sensor array output signal to effectively amplify the weak signal.

[0067] 2. Select a suitable analog-to-digital converter to convert the analog signal output by the preamplifier into a digital signal, ensuring that the conversion accuracy and speed meet the system requirements.

[0068] 3. Design a dual-band bandpass filter using a cascaded elliptical filter topology. Determine the filter component parameters and circuit structure based on the parameter requirements of the main frequency channel and auxiliary frequency channel (main frequency channel center frequency 10kHz±50Hz, stopband attenuation ≥80dB@1MHz; auxiliary frequency channel center frequency 100kHz±20kHz, quality factor Q≥50; group delay fluctuation ≤5ns).

[0069] 4. Write an adaptive Kalman filter algorithm program in the embedded processor to realize the temperature drift compensation function (temperature-magnetic field coupling model established based on finite element analysis), stress correction model (H correction=α·ε+β·dε / dt, where α=0.15±0.02, β=0.08±0.01) and the functions of a dynamic noise covariance matrix update module (update frequency is 1kHz±10%).

[0070] (4) Implementation of insulation shielding module

[0071] 1. Create a three-layer electromagnetic shielding system. Use appropriate magnetic materials for the magnetic layer, conductive materials for the shielding layer, and protective materials for the protective layer. Install the magnetic layer, shielding layer, and protective layer in order from the inside out, ensuring that each layer fits tightly together to form an effective electromagnetic shielding structure.

[0072] 2. Install the partial discharge monitoring module, connect the capacitive coupling electrode to the main insulation layer, install the high-frequency current sensor and ultra-high frequency antenna array in the appropriate position, and transmit the signal to the signal processing module through the circuit connection. Program a wavelet packet decomposition algorithm in the signal processing module to extract the discharge characteristics in the 0.1-30 MHz frequency band to achieve real-time monitoring of partial discharge.

[0073] (V) Implementation of the reliability assurance module

[0074] 1. Integrate the partial discharge monitoring unit and connect it to the signal output terminal of the partial discharge monitoring module to receive the partial discharge signal in real time and perform analysis and judgment.

[0075] 2. Design a hardware watchdog circuit, select a suitable watchdog chip, connect it to the embedded processor, and set a suitable timing to ensure that the system can be reset in time when a fault such as a freeze or program runaway occurs.

[0076] 3. Build a dual power supply redundant system, select two independent power supply modules, and realize automatic switching between the two power supply modules through the power switching circuit to ensure that the system can still work normally when one power supply fails.

[0077] (6) Implementation of temperature compensation module

[0078] 1. Embed the PT100 thin film temperature sensor 1mm below the sensor substrate to ensure that it can accurately measure the sensor temperature.

[0079] 2. Store the compensation coefficient of the temperature-sensitivity compensation model in the EEPROM memory (S(T)=S0·[1+α(T-T0)+β(T-T0) 2 ]), and write a program to call the compensation coefficient in a 100ms cycle, execute the finite element temperature field correction algorithm, and perform temperature compensation on the sensitivity of the GMR sensor.

[0080] (VII) Implementation of modular architecture

[0081] 1. Design standardized interface components, adopt DIN rail and PCB stamp hole connection methods, and make corresponding interface circuits and connectors to ensure convenient connection and communication between system modules.

[0082] Select appropriate hot-swappable connectors and install them in appropriate locations on the sensor array, signal processing board, and shielding structure to enable hot-swappable replacement of these modules:

[0083] A specific application of this embodiment is as follows:

[0084] (1) Scenario Description

[0085] A TV modification project for a power distribution cabinet required the installation of a current measurement system based on GMR sensors without affecting the operation of the main equipment. This system was designed to achieve the following functions:

[0086] 1. 0.1% accuracy current monitoring during normal operation

[0087] 2. 100kHz high frequency signal capture in case of fault

[0088] 3. Online monitoring of insulation status

[0089] 4. Live maintenance capability

[0090] (2) Implementation steps

[0091] 1. Installation of composite magnetic circuit module

[0092] Step 1: Install a conical ferrite magnetic ring (inner diameter φ120mm, taper 15°) on the primary winding side of the TV.

[0093] Step 2: Use a laser locator to adjust the air gap between the main magnetic circuit and the auxiliary magnetic circuit to 0.2mm, and apply a nano-ceramic insulation layer;

[0094] Step 3: Keep a 1mm distance between the spiral magnetic focuser (made of Permalloy, with a helical angle of 35°) and the GMR sensor;

[0095] 2. GMR sensor array deployment

[0096] Step 1: Arrange three groups of orthogonal dual sensor arrays in the non-saturated region (B<0.3T) of the auxiliary magnetic circuit ring core;

[0097] Step 2: Install the sensor using PCB patch technology, maintaining a 2mm axial spacing;

[0098] Step 3: Connect the differential output channel to the signal conditioning circuit, and the single-ended output to the temperature compensation module;

[0099] 3. Signal processing module integration

[0100] Step 1: Use a low-noise op amp (AD8221, noise density 1.2nV / √Hz) as the preamplifier.

[0101] Step 2: The dual-band pass filter uses a cascaded elliptic filter (MAX274 chip);

[0102] Step 3: The embedded processor (STM32H743) runs the adaptive Kalman filter algorithm with an update frequency of 1kHz

[0103] 4. Insulation shielding and reliability configuration

[0104] Step 1: The three shielding layers are Permalloy (magnetic conductivity), copper foil (shielding), and epoxy resin (protection).

[0105] Step 2: The partial discharge monitoring module is connected to the main insulation layer through three capacitive coupling electrodes (100pF);

[0106] Step 3: Configure the dual power supply redundant system with a supercapacitor energy storage module (maintaining power supply for 10 minutes);

[0107] 5. Temperature compensation and calibration

[0108] Step 1: The PT100 thin film sensor (accuracy ±0.1°C) is embedded under the sensor substrate;

[0109] Step 2: EEPROM stores the three-point calibration coefficients at 25°C, 50°C, and 85°C.

[0110] Step 3: Execute the finite element temperature field correction algorithm every 100ms.

[0111] Working Principle: The magnetic field generated by the busbar current is split into two paths by a flux separator. The high-frequency magnetic field is enhanced by a spiral focuser and detected by a GMR sensor. The signal processing module filters interference and calculates the true current value. The temperature compensation module calibrates the ambient temperature in real time. The insulation monitoring module simultaneously checks the health status of the equipment.

[0112] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0113] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. The electromagnetic voltage transformer primary current measurement system based on GMR sensor is characterized by: include: A composite magnetic circuit module includes a conical ferrite magnetic concentrator, a main magnetic circuit, and an auxiliary magnetic circuit. The conical ferrite magnetic concentrator, the main magnetic circuit, and the auxiliary magnetic circuit form a magnetic flux separation structure. The main magnetic circuit is configured to conduct power frequency magnetic flux to the iron core, and the auxiliary magnetic circuit is configured to conduct high frequency magnetic flux to the GMR sensor array. The auxiliary magnetic circuit includes a spiral magnetic focuser. The main and auxiliary magnetic circuits are coupled via a non-contact air gap to form a closed magnetic flux loop. The GMR sensor array module is arranged in the non-saturated area of ​​the annular core of the auxiliary magnetic circuit, adopts a combination of an orthogonal dual sensor array and an annular distribution, and is equipped with a differential output channel to eliminate position deviation; A signal processing module, comprising a preamplifier, an analog-to-digital converter, a dual-frequency bandpass filter, and an embedded processor connected in sequence, wherein the embedded processor is configured with an adaptive Kalman filter algorithm; The insulation shielding module includes a three-layer electromagnetic shielding system and a partial discharge monitoring module. The three-layer electromagnetic shielding system is composed of a magnetic conductive layer, a shielding layer, and a protective layer from the inside to the outside. Reliability assurance module, integrating partial discharge monitoring unit, hardware watchdog circuit and dual power supply redundancy system; Temperature compensation module, including PT100 thin film temperature sensor and EEPROM memory.

2. The electromagnetic voltage transformer primary current measurement system based on a GMR sensor according to claim 1, characterized in that: Also included is a modular architecture that includes: Standardized interface components, supporting DIN rail and PCB stamp hole connection; Hot-swappable connectors support live replacement of sensor arrays, signal processing boards, and shielding structures.

3. The electromagnetic voltage transformer primary current measurement system based on a GMR sensor according to claim 1, characterized in that: In the composite magnetic circuit structure: The air gap height between the conical ferrite magnetic focusing ring of the main magnetic circuit and the spiral magnetic focuser of the auxiliary magnetic circuit is 0.1-0.3 mm, and a nano-ceramic insulating layer is provided in the air gap area.

4. The electromagnetic voltage transformer primary current measurement system based on a GMR sensor according to claim 3, characterized in that: The spiral magnetic focuser is made of Permalloy material with a magnetic permeability of >100,000, a spiral angle designed to be 35°±1°, a 2μm thick insulating coating on the surface, and a distance from the GMR sensor controlled to be in the range of 0.5-1.5mm.

5. The electromagnetic voltage transformer primary current measurement system based on a GMR sensor according to claim 1, characterized in that: In the GMR sensor array module: The orthogonal dual sensor group is arranged at 90 degrees orthogonally, with an axial spacing of 2mm, and is distributed in an annular manner on the inner wall of the conical magnetic ring; The differential output channel connects the output ends of the two sets of sensors to eliminate the magnetic field detection error caused by sensor position deviation; The single-ended output channel is connected to the temperature compensation module to achieve synchronous acquisition of multi-physics field coupled signals.

6. The electromagnetic voltage transformer primary current measurement system based on a GMR sensor according to claim 1, characterized in that: The dual-frequency bandpass filter satisfies: Main frequency channel: center frequency 10kHz±50Hz, stopband attenuation ≥80dB@1MHz; Auxiliary frequency channel: center frequency 100kHz±20kHz, quality factor Q≥50; Adopting cascaded elliptical filter topology, the group delay fluctuation is ≤5ns.

7. The electromagnetic voltage transformer primary current measurement system based on a GMR sensor according to claim 1, characterized in that: The partial discharge monitoring module is connected to the main insulation layer through a capacitive coupling electrode, includes a high-frequency current sensor and an ultra-high frequency antenna array, and uses a wavelet packet decomposition algorithm to extract discharge characteristics in the 0.1-30 MHz frequency band.

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