Electromagnetic voltage transformer primary current measuring system based on GMR sensor

Abstract

The invention discloses an electromagnetic voltage transformer primary current measurement system based on a GMR sensor, and relates to the technical field of power system monitoring. Comprising a composite magnetic circuit module, magnetic flux separation is achieved through a conical ferrite magnetism gathering ring, a main magnetic circuit and an auxiliary magnetic circuit, power frequency magnetic flux is conducted to an iron core, and high-frequency magnetic flux is conducted to a GMR sensor array. The GMR sensor array adopts the combination of orthogonal double sensors and annular distribution, and is provided with a differential output channel, so that the position deviation is effectively eliminated. The signal processing module integrates a pre-amplifier, an analog-to-digital converter, a dual-frequency band-pass filter and an embedded processor, executes an adaptive Kalman filtering algorithm, and improves the signal processing precision. The system is also provided with an insulation shielding module, a reliability guarantee module and a temperature compensation module which respectively provide electromagnetic shielding, hardware monitoring, dual-power redundancy and environment temperature compensation functions, and safe and stable operation of the measurement system is ensured. The method is suitable for current measurement in an electric power system, and has remarkable technical advantages and practical value.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system monitoring, and particularly relates to a primary current measurement system for electromagnetic voltage transformers based on GMR sensors. Background Art

[0002] During the operation and monitoring of power systems, accurately detecting parameters such as current and magnetic field is crucial for ensuring the safe and stable operation of the system. Traditional detection technologies have many deficiencies. For example, the magnetic circuit design is not optimized enough, resulting in low sensitivity of magnetic field detection; the anti-interference ability of the signal processing system is weak, affecting the detection accuracy; the high-voltage insulation performance is poor, prone to causing safety accidents; at the same time, the lack of effective calibration mechanisms and modular designs is not conducive to the maintenance and upgrading of equipment. With the development of smart grids, higher requirements are put forward for the accuracy and stability of current measurement. GMR sensors show great potential in the field of current measurement due to their high sensitivity, low power consumption, and easy integration. However, how to effectively utilize GMR sensors to construct a high-performance current measurement system, especially how to achieve accurate measurement in a complex electromagnetic environment, remains a hot topic and a difficult point in current research. Summary of the Invention

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

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

[0005] The present invention is a primary current measurement system for electromagnetic voltage transformers based on GMR sensors, including:

[0006] A composite magnetic circuit module, including a conical ferrite magnetic focusing ring, a main magnetic circuit, and an auxiliary magnetic circuit. The conical ferrite magnetic focusing ring, the main magnetic circuit, and the auxiliary magnetic circuit form a magnetic flux separation structure. Among them, 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 focusing device. The main magnetic circuit and the auxiliary magnetic circuit form a closed magnetic flux loop through non-contact air gap coupling;

[0007] A GMR sensor array module, arranged in the non-saturated region of the toroidal iron core of the auxiliary magnetic circuit, adopting a combination of an orthogonal dual-sensor array and a toroidal distribution, and equipped with a differential output channel for eliminating position deviation;

[0008] The signal processing module includes a preamplifier, an analog-to-digital converter, a dual-bandpass filter, and an embedded processor connected in sequence. The embedded processor is configured to execute an adaptive Kalman filtering 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 includes a magnetic conductive layer, a shielding layer, and a protective layer from the inside to the outside in sequence;

[0010] The reliability guarantee module integrates a partial discharge monitoring unit, a hardware watchdog circuit, and a dual-power redundancy system;

[0011] The temperature compensation module includes a PT100 thin-film temperature sensor and an EEPROM memory.

[0012] As a preferred technical solution of the present invention, it further includes a modular architecture, and this modular architecture includes:

[0013] A standardized interface component that supports DIN rail type and PCB pinhole connection methods;

[0014] A hot-swap connector that supports hot replacement of the sensor array, the signal processing board, and the 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 concentrating ring of the main magnetic circuit and the spiral magnetic focusing device 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, the magnetic permeability > 100000, the spiral helix angle is designed to be 35° ± 1°, and a 2-μm-thick insulating coating is plated on the surface, and the distance from the GMR sensor is controlled within the range of 0.5 - 1.5 mm.

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

[0018] The orthogonal dual-sensor groups are arranged orthogonally at 90°, the axial distance is 2 mm, and they are annularly distributed on the inner wall of the conical magnetic concentrating ring;

[0019] The differential output channel is connected to the output ends of the two groups of sensors to eliminate the magnetic field detection error caused by the position deviation of the sensors;

[0020] The single-ended output channel is connected to the temperature compensation module to realize synchronous acquisition of multi-physical field coupling 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, temperature-magnetic field coupling model established based on finite element analysis;

[0023] Stress correction model, satisfying

[0024] H correction = α·ε + β·dε / dt

[0025] where α = 0.15 ± 0.02 and 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-band pass 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 a cascaded elliptic filter topology structure, group delay fluctuation ≤ 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) = S 0 ·[1 + α(T - T 0 ) + β(T - T 0 ) 2

[0035] The EEPROM memory calls the compensation coefficient at a 100ms cycle and executes the finite element temperature field correction algorithm.

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

[0037] High-precision measurement: By implementing magnetic flux separation through the composite magnetic circuit module, accurately detecting high-frequency magnetic flux using the GMR sensor array module, and combining the adaptive Kalman filtering algorithm and the dual-band pass filter of the signal processing module, the measurement accuracy is effectively improved. ​

[0038] Strong anti-interference ability: 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 anti-interference ability and reliability of the system.

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

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

[0041] Of course, it is not necessary for any product implementing the present invention to achieve all the above advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for describing the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

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

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

[0045] Figure 3 It is the schematic diagram of the GMR sensor array module in the present invention;

[0046] Figure 4 It is the internal schematic diagram of the composite magnetic circuit module in the present invention;

[0047] Figure 5 It is the signal processing flow block diagram in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0049] Please refer to Figures 1-5As shown, the present invention discloses a primary current measurement system for an electromagnetic voltage transformer based on a GMR sensor, including:

[0050] A composite magnetic circuit module, including a conical ferrite magnetic concentrating ring, a main magnetic circuit, and an auxiliary magnetic circuit. The conical ferrite magnetic concentrating ring and 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 concentrator. The main magnetic circuit and the auxiliary magnetic circuit form a closed magnetic flux loop through non-contact air gap coupling;

[0051] A GMR sensor array module, which is arranged in the non-saturated area of the toroidal iron core of the auxiliary magnetic circuit, adopts a combination of an orthogonal dual-sensor array and a toroidal distribution, and is equipped with a differential output channel for eliminating position deviation;

[0052] A signal processing module, including a preamplifier, an analog-to-digital converter, a dual-band pass filter, and an embedded processor connected in sequence. The embedded processor is configured to execute an adaptive Kalman filtering algorithm;

[0053] An insulation shielding module, including a three-layer electromagnetic shielding system and a partial discharge monitoring module. The three-layer electromagnetic shielding system includes a magnetic conduction layer, a shielding layer, and a protection layer from the inside to the outside in sequence;

[0054] A reliability guarantee module, integrating a partial discharge monitoring unit, a hardware watchdog circuit, and a dual-power redundancy system;

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

[0056] In this embodiment, the separation and conduction of magnetic flux are realized through the composite magnetic circuit module, and high-precision measurement is carried out by using the GMR sensor array module; the signal processing module adopts an adaptive Kalman filtering algorithm to improve the accuracy and stability of signal processing; the insulation shielding module and the reliability guarantee module provide electromagnetic shielding and reliability guarantee to ensure the 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 specific implementation of the present invention is as follows:

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

[0059] 1. Select a suitable conical ferrite magnetic concentrating ring, and its material and size are designed according to actual measurement requirements. Install the conical ferrite magnetic concentrating ring at a suitable position on the main magnetic circuit to ensure its close fit with the iron core of the main magnetic circuit to effectively conduct power frequency magnetic flux.

[0060] 2. Fabricate a spiral magnetic focusing device for the auxiliary magnetic circuit using permalloy material. Ensure a spiral lift angle of 35° ± 1° through precision machining processes, and coat its surface with an insulating coating 2 μm thick. Install the spiral magnetic focusing device in the auxiliary magnetic circuit, maintaining an air gap of 0.1 - 0.3 mm between it and the conical ferrite magnetic concentrating ring, and apply a nano-ceramic insulating material in the air gap region 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 loop through non-contact air gap coupling, ensuring that the power frequency magnetic flux and the high frequency magnetic flux can be effectively conducted along the main magnetic circuit and the auxiliary magnetic circuit respectively.

[0062] (II) Implementation of the GMR sensor array module

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

[0064] 2. Connect the differential output channels and the single-ended output channels. Connect the differential output channels to the output terminals of the two groups of sensors to eliminate the magnetic field detection error caused by the position deviation of the sensors through circuit design; connect the single-ended output channels to the temperature compensation module to achieve synchronous acquisition of multi-physical field coupling signals.

[0065] (III) Implementation of the signal processing module

[0066] 1. Select a suitable preamplifier, and set parameters such as the gain and bandwidth of the preamplifier according to the characteristics of the output signals of the GMR sensor array to effectively amplify weak signals.

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

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

[0069] 4. Write an adaptive Kalman filter algorithm program in the embedded processor to implement 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 and β = 0.08 ± 0.01), and the function of the dynamic noise covariance matrix update module (update frequency is 1 kHz ± 10%).

[0070] (IV) Implementation of the insulation shielding module

[0071] 1. Fabricate a three-layer electromagnetic shielding system. Select a suitable magnetic conductive material to make the magnetic conductive layer, a conductive material to make the shielding layer, and a protective material to make the protective layer. Install the magnetic conductive layer, shielding layer, and protective layer in sequence from the inside to the outside, ensuring tight fitting between each layer 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, and install the high-frequency current sensor and the ultra-high frequency antenna array at appropriate positions. Transmit the signals to the signal processing module through circuit connections. Write a wavelet packet decomposition algorithm program in the signal processing module to extract the discharge characteristics in the frequency band of 0.1 - 30 MHz to achieve real-time monitoring of partial discharge.

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

[0074] 1. Integrate the partial discharge monitoring unit, connect it to the signal output terminal of the partial discharge monitoring module, receive the partial discharge signals 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 an appropriate timing time to ensure that the system can be reset in a timely manner when faults such as system freeze or program runaway occur.

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

[0077] (VI) Implementation of the temperature compensation module

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

[0079] 2. Store the compensation coefficients of the temperature-sensitivity compensation model (S(T) = S 0 ·[1 + α(T - T 0 ) + β(T - T 0 ) 2 ) in the EEPROM memory, and write a program to call the compensation coefficients at a 100 ms cycle, execute the finite element temperature field correction algorithm, and perform temperature compensation on the sensitivity of the GMR sensor.

[0080] (7) Implementation of the modular architecture

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

[0082] Select appropriate hot-swap connectors and install them at suitable positions on the sensor array, signal processing board, and shielding structure to achieve the hot-swap function of these modules:

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

[0084] (1) Scenario description

[0085] For a TV transformation project of a power distribution cabinet, it is necessary to install a current measurement system based on GMR sensors without affecting the operation of the main equipment to achieve the following functions:

[0086] 1. Current monitoring with an accuracy of 0.1% during normal operation

[0087] 2. Capture of 100 kHz high-frequency signals during faults

[0088] 3. Online monitoring of insulation status

[0089] 4. Capability of live maintenance

[0090] (2) Implementation steps

[0091] 1. Installation of the composite magnetic circuit module

[0092] Step 1: Install a conical ferrite magnetic concentrator (inner diameter φ120 mm, taper 15°) on the primary winding side of the TV;

[0093] Step 2: Adjust the air gap between the main magnetic circuit and the auxiliary magnetic circuit to 0.2 mm through a laser locator and coat a nano-ceramic insulation layer;

[0094] Step 3: Keep a 1 mm spacing between the spiral magnetic concentrator (made of permalloy, spiral lead angle 35°) and the GMR sensor;

[0095] 2. Deployment of the GMR sensor array

[0096] Step 1: Arrange 3 groups of orthogonal dual-sensor arrays in the non-saturated region (B < 0.3 T) of the annular iron core of the auxiliary magnetic circuit;

[0097] Step 2: Install the sensors using the PCB soldering process and keep an axial spacing of 2 mm;

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

[0099] 3. Signal Processing Module Integration

[0100] Step 1: The preamplifier uses a low-noise operational amplifier (AD8221, noise density 1.2 nV / √Hz).

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

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

[0103] 4. Insulation Shielding and Reliability Configuration

[0104] Step 1: The three-layer shielding layer is composed of permalloy (magnetic conductive), copper foil (shielding), and epoxy resin (protection) in sequence.

[0105] Step 2: The partial discharge monitoring module is connected to the main insulation layer through 3 capacitive coupling electrodes (100 pF).

[0106] Step 3: The dual-power redundant system is configured with a supercapacitor energy storage module (maintaining a 10-minute power supply).

[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: The EEPROM stores the calibration coefficients at three points of 25 °C / 50 °C / 85 °C.

[0110] Step 3: The finite element temperature field correction algorithm is executed every 100 ms.

[0111] Working Principle: The magnetic field generated by the busbar current is divided into two paths through the magnetic flux separator; the high-frequency magnetic field is enhanced by the spiral concentrator and then detected by the GMR sensor; the signal processing module filters out interference and calculates the true current value; the temperature compensation module calibrates the influence of the ambient temperature in real time; the insulation monitoring module synchronously checks the health status of the device.

[0112] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0113] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited 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 in that: include: A composite magnetic circuit module, comprising 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 through a non-contact air gap to form a closed magnetic flux loop; The GMR sensor array module is arranged in the non-saturated region of the annular core of the auxiliary magnetic circuit, adopts a combination of an orthogonal dual sensor array and 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 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 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 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 focusing device of the auxiliary magnetic circuit is 0.1-0.3 mm, and a nano ceramic insulating layer is arranged in the air gap area.

4. The electromagnetic voltage transformer primary current measurement system based on GMR sensor according to claim 3, characterized in that: The spiral magnetic concentrator is made of Permalloy material with a magnetic permeability of >100000, 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 GMR sensor according to claim 1, characterized in that: In the GMR sensor array module: The orthogonal dual sensor group is arranged orthogonally at 90 degrees, with an axial spacing of 2 mm, and is distributed in an annular manner on the inner wall of the conical magnetic focusing 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 GMR sensor according to claim 1, characterized in that: The adaptive Kalman filter algorithm of the signal processing module includes: Temperature drift compensation function, based on the temperature-magnetic field coupling model established by finite element analysis; Stress correction model, satisfying H correction =α·ε+β·dε / dt Among them, α=0.15±0.02, β=0.08±0.01; Dynamic noise covariance matrix update module, whose update frequency is 1kHz±10%.

7. The electromagnetic voltage transformer primary current measurement system based on 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.

8. The electromagnetic voltage transformer primary current measurement system based on 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.

9. The electromagnetic voltage transformer primary current measurement system based on GMR sensor according to claim 1, characterized in that: In the temperature compensation module: PT100 thin film temperature sensor embedded 1mm below the sensor substrate Establishing temperature-sensitivity compensation model: S(T)=S0·[1+α(T-T0)+β(T-T0) 2 ] The EEPROM memory calls the compensation coefficients in a 100ms cycle to execute the finite element temperature field correction algorithm.

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