Virtual power plant load end three-phase five-core cable non-contact current measuring device and method

Abstract

The invention discloses a virtual power plant load end three-phase five-core cable non-contact current measuring device and method, and the device comprises an annular array which is composed of six fluxgate sensors and is fixed at the periphery of a cable through a buckle type fixing structure; the signal processing unit adopts a main control chip, and integrates a 12-bit ADC and a low-noise amplification circuit; and the wireless communication module supports BLE5.0 multi-device networking. According to the measurement method, a magnetic field distribution matrix model is established based on the Biot-Savart law, each phase current, a neutral current and a leakage current are decoupled through inverse matrix operation, and real-time calibration is realized by using a redundant sensor. According to the invention, compact design is realized, the measurement precision is improved, the leakage current resolution is 40mA, work in an environment of-20 DEG C to 80 DEG C is supported, and the device has the characteristics of convenience in installation, strong anti-interference performance, low power consumption and the like, and is suitable for real-time monitoring and intelligent scheduling of a load side of a virtual power plant.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electric power measurement, and particularly relates to a non-contact current measurement device and method for a three-phase five-core cable at a load end of a virtual power plant. BACKGROUND

[0002] With the wide application of virtual power plants in smart grids, the demand for current measurement at the load end is increasing. Virtual power plants realize precise scheduling and reasonable distribution of energy by real-time monitoring and optimizing power data at the load side, thereby improving the stability of the power grid. The current monitoring method at the load end is still mainly contact measurement. Traditional current transformers, Rogowski coils and other methods have many limitations in deployment and maintenance, and it is difficult to meet the needs of virtual power plants for flexible, high-precision and low-power measurement.

[0003] Currently, current measurement methods are mainly divided into invasive and non-invasive types:

[0004] Invasive measurement methods usually use sampling circuits to directly measure current, which has high precision, but the application is limited because it needs to physically modify the cable or circuit.

[0005] Non-invasive measurement mainly relies on electromagnetic induction, magnetic field inversion and other technologies, and does not need to damage the measured object, but the existing non-contact solutions still have many shortcomings in measurement accuracy, adaptability and installation convenience. The common implementation of current measurement technology includes current transformers, Hall sensors, Rogowski coils, etc. Among them, current transformers are suitable for traditional single-core cable measurement, but in multi-core cables, the measurement error increases due to the magnetic field superposition effect; Hall sensors have a large measurement bandwidth, but are affected by temperature drift and have low stability; Rogowski coils have simple structure and good isolation, but are easily disturbed by external magnetic fields; in addition, the existing multi-sensor array scheme usually uses a four-sensor mode, which cannot monitor the ground current, resulting in weak fault tolerance of the system in the case of unbalanced load or sensor failure.

[0006] For the current monitoring needs of three-phase five-core cables, the existing technology cannot simultaneously meet the high sensitivity, strong fault tolerance and low-power wireless transmission needs of three-phase five-core cable current measurement. It is difficult to accurately decouple the measurement of each phase current of the cable at the load end, especially in unbalanced load, leakage detection and harmonic analysis scenarios, the traditional method has a large measurement error, which affects the safety and stability of the power system.

[0007] Therefore, there is an urgent need for a compact, non-contact current measurement scheme that can accurately decouple each phase current, neutral current and leakage current without modifying the cable structure, and has self-calibration, redundant fault tolerance and wireless networking functions to support the real-time monitoring and intelligent scheduling needs of virtual power plants. SUMMARY

[0008] In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a virtual power plant load end three-phase five-core cable non-contact current measurement device and method, which realizes accurate measurement of the current of each phase of the three-phase five-core cable, the neutral line current and the leakage current by optimizing the sensor layout through electromagnetic field simulation, combining a magnetic flux gate sensor and a high-precision circuit design.

[0009] The technical solution of the present application is as follows:

[0010] A virtual power plant load end three-phase five-core cable non-contact current measurement device, characterized in that it comprises:

[0011] A ring-shaped magnetic sensor array, wherein six magnetic flux gate sensors are uniformly arranged on the periphery of the cable to be measured, five of which correspond to the magnetic field measurement of the three-phase live wire, the neutral line and the ground wire, and the sixth sensor is a redundant sensor for real-time calibration and fault tolerance;

[0012] A buckle type fixing structure for fixing the magnetic flux gate sensor on the surface of the cable and ensuring that each sensor is concentric with the cable;

[0013] A signal acquisition and processing unit electrically connected to the ring-shaped magnetic sensor array for acquiring and processing magnetic field signals;

[0014] A wireless communication module connected to the signal acquisition and processing unit for remotely transmitting measurement data to a monitoring system.

[0015] Further, the magnetic flux gate sensor is a DRV425 type magnetic flux gate sensor uniformly arranged on a ring-shaped PCB board at an interval of 60°.

[0016] Further, the buckle type structure is made of ABS engineering plastic with an inner diameter of 6mm.

[0017] Further, the signal acquisition and processing circuit comprises:

[0018] A master control chip for executing a current decoupling algorithm;

[0019] A low-noise amplification circuit, the input end of which is connected to the output end of each magnetic flux gate sensor;

[0020] A 12-bit ADC sampling circuit, the input end of which is connected to the output end of the low-noise amplification circuit, and the output end of which is connected to the ADC interface of the master control chip.

[0021] Further, the signal acquisition and processing circuit further comprises:

[0022] A temperature compensation circuit integrated in the low-noise amplification circuit for eliminating the temperature drift of the DRV425 sensor;

[0023] Digital filter algorithm, running in the main control chip, is used to suppress 50Hz power frequency interference.

[0024] Further, the sampling rate of the 12-bit ADC sampling circuit is 10kSPS, and the dynamic range covers the measured cable current of 0.1mA-1000A.

[0025] Further, the wireless communication module is a RF-BM-4044B4 type BLE5.0 module, which supports multi-device networking.

[0026] Secondly, the application also provides a current measurement method based on the above device, characterized by comprising the following steps:

[0027] S1. Sensor array installation: the buckle type fixing structure is sleeved on the cable, each sensor is installed on the cable through the buckle type fixing structure, and the initial coefficient matrix K is calibrated to ensure that each fluxgate sensor is concentric with the cable;

[0028] S2. Magnetic field signal acquisition: the annular magnetic sensor array synchronously acquires the magnetic field signal around the cable, which is amplified, filtered and converted into a digital signal by the signal acquisition processing unit (4);

[0029] S3. Current decoupling calculation: the main control chip executes the following algorithm:

[0030] S3.1 Based on the Biot-Savart law, a magnetic field distribution matrix model of the five-core cable is established:

[0031]

[0032] wherein, is the current vector of each wire, is the theoretical magnetic field distribution matrix; μ0 is the magnetic permeability of vacuum;

[0033] S3.2 Decouple each wire current by inverse matrix operation:

[0034]

[0035] S4. Redundancy check: compare the measured value of the 6th sensor with the theoretical value, and trigger the calibration program when the deviation exceeds 5%;

[0036] S5. Data wireless transmission: upload the current data and device state information to the monitoring terminal.

[0037] Further, step (3) further comprises a dynamic compensation algorithm:

[0038] Real-time monitoring of ambient temperature, correction of sensor gain through temperature compensation circuit;

[0039] When the cable position offset is detected, the parameters of the matrix K are automatically updated.

[0040] Further, in step S4, the trigger threshold of the redundancy check is 5%, and the redundant sensor is preferentially used to replace the abnormal channel data during calibration.

[0041] Further, in step S5, the data uploading frequency of the wireless communication module can be dynamically adjusted.

[0042] Compared with the prior art, the present application has the following advantages:

[0043] The annular magnetic array structure and the magnetic flux gate sensor are adopted to realize non-contact high-precision measurement of the currents of each core of the three-phase five-core cable, avoid physical modification of the cable, and improve the safety and adaptability of measurement. The calibration matrix is introduced to significantly improve the decoupling precision and anti-interference ability. The device has self-calibration and redundancy fault tolerance functions, can maintain measurement accuracy in the case of sensor offset or failure, and enhances the robustness of the system. At the same time, combined with the wireless communication module, remote data transmission and multi-point networking are realized, which is suitable for real-time current monitoring in complex scenes such as virtual power plants. The overall scheme has compact structure, convenient installation, wide measurement range, and good engineering application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 : The structure diagram of the virtual power plant load end three-phase five-core cable non-contact current measurement device of the present application; wherein, the upper left diagram is a schematic diagram of the cable passing through the device and being locked, the upper right diagram is a perspective view of the annular magnetic array structure and the magnetic flux gate sensor in the device, the lower left diagram is a schematic diagram of the device lock being opened, and the lower right diagram is a perspective view of the signal acquisition and processing unit and the wireless communication module;

[0045] Figure 2 : Multi-core cable magnetic field distribution model;

[0046] Figure 3 : The principle diagram of the signal acquisition and processing circuit of the present application;

[0047] Figure 4 : Sensor and amplifier circuit;

[0048] Figure 5 : Measurement scene schematic diagram;

[0049] In the figure: 1-annular magnetic sensor array, 2-buckling type fixing structure, 3-cable, 4-signal acquisition and processing unit, 5-wireless communication module, L1-L3-three-phase live wire, N-neutral wire, PE-ground wire. DETAILED DESCRIPTION

[0050] The specific embodiments of the present application will be described below with reference to the drawings. The embodiments of the present application can be implemented in various different forms and are not limited to the embodiments described herein. These embodiments are provided so that the present disclosure is more thorough and complete, and to fully convey the concept of the present application to those skilled in the art.

[0051] Device configuration

[0052] Ring-shaped magnetic sensor array: 6 single-axis fluxgate sensors (Texas Instruments DRV425) are arranged in a ring around the cable to be measured. 5 of them are used to sense the magnetic field generated by the three-phase live wire, neutral wire and ground wire (or leakage current main path) respectively. The 6th sensor is a redundant sensor used for system fault-tolerant calibration or performance verification to improve the robustness of the measurement system.

[0053] Mechanical fixing structure: a buckle-type mechanical structure is designed to securely fix the ring-shaped magnetic sensor array on the periphery of the cable. This structure does not require additional auxiliary supports and can be installed quickly by one person. It will not cause any damage to the cable insulation layer and does not need to interrupt the power supply. This structure is suitable for standard cables with a diameter of 5 cm or less.

[0054] Signal conditioning and acquisition circuit: the weak magnetic signal output by the sensor is first amplified by a low-noise amplification circuit. The amplified signal is connected to the 12-bit analog-to-digital converter built into the microcontroller unit. The microcontroller unit is configured with a sampling rate of up to 10 ksps, ensuring that the system can capture rapid changes in current. The dynamic range covers from very low (0.1 mA) to very high (1000 A) current values, meeting the requirements of wide-range measurement.

[0055] Wireless communication module: integrated RF-BM-4044B4 Bluetooth module. This module supports flexible configuration of transmission intervals, allowing users to set the data transmission frequency according to the application scenario (such as real-time monitoring or periodic reporting). In open environments, its transmission distance can reach more than 150 meters, sufficient to cover the monitoring needs of most places. At the same time, this module supports multi-device networking, allowing multiple measurement devices to upload data synchronously to a unified cloud platform or local monitoring system.

[0056] Calculation method

[0057] Matrix establishment and calibration: the currents of the five wires to be measured (three-phase live wire, neutral wire, ground wire) are regarded as unknown variables, and the magnetic field values measured by the five main sensors are regarded as known quantities. According to the magnetic field model, the magnetic field distribution matrix equation is established where B is the magnetic field vector measured by the sensor, is the current vector of each wire, The theoretical magnetic field distribution matrix. Through the accurate pre-calibration process of the device, a correction coefficient matrix K is obtained. This matrix K integrates factors such as cable radius, distance from cable center to core wire, and sensor deflection angle.

[0058] Coefficient matrix solution and inversion: the final current calculation formula is The measured magnetic field vector Multiply the pre-calibration coefficient matrix K, and the actual current value of each conductor can be calculated by inversion.

[0059] Redundant calibration and fault tolerance: the magnetic field data measured by the 6th redundant sensor can be compared with the theoretical model prediction value or other sensor data. It is used to monitor the system state in real time, identify possible sensor failures or severe interference, and start the calibration program or switch to the backup measurement mode when necessary to ensure the reliability of the measurement results.

[0060] Example 1: Sensor array and structure design

[0061] This example introduces the specific installation steps and structure design of the non-contact current measurement device for three-phase five-core cables.

[0062] The sensor array is composed of six DRV425 single-axis fluxgate sensors, which are evenly distributed in a ring on the PCB board and fixed to the outside of the measured cable through an ABS engineering plastic buckle shell. The inner diameter of the shell is designed to be 6mm, which ensures stable installation on cables with a diameter of ≤60mm without damaging the cable insulation layer or power-off operation. The shell has a quick disassembly mechanism and is suitable for flexible application in complex environments.

[0063] DRV425 is a high-precision integrated fluxgate sensor designed for single-axis magnetic field sensing, suitable for applications requiring fast switching frequency and high-precision measurement. The sensor uses a non-magnetic, ultra-thin quad flat no-lead (WQFN) package, with an operating temperature range of -40°C to +125°C, suitable for industrial and automotive environments. Its main features include an offset of ±8μT, an offset drift of ±5nT / °C, a gain error of 0.04%, a gain drift of ±7ppm / °C, a linearity of ±0.1%, and a noise of 1.5nT / √Hz, with a sensor range of ±2mT. DRV425 supports external resistance adjustment range and gain, with a selectable bandwidth of 47kHz or 32kHz, suitable for scenarios requiring high-precision magnetic field measurement. The sensor has a built-in precision reference and differential amplifier, which can minimize component count and reduce system cost. Its output is an analog signal proportional to the induced magnetic field, suitable for linear position sensing, bus current sensing, wiring current sensing, general magnetic field sensor, overcurrent detection, motor reliability diagnosis, frequency and voltage inverter, and solar inverter applications. DRV425-BUSBAR-EVM is a complete busbar assembly for ±100A non-invasive (isolated) current measurement solutions.

[0064] In practical applications, DRV425 measures current by detecting changes in the magnetic field, with its sensitivity inversely proportional to the distance to the current-carrying conductor. By placing two DRV425 devices in the hollow center of the busbar, high current flowing through the busbar can be detected. In addition, DRV425 also supports multi-device networking, allowing multiple measurement devices to build a distributed monitoring network to achieve remote data acquisition and management on the load side. The low power consumption of DRV425 makes it an ideal choice for battery-powered or low-power systems, while its compact package and high performance make it widely applicable in industrial automation, smart home, health care, sports measurement, and other fields.

[0065] DRV425 has an internal function of a fluxgate sensor and a compensation coil to achieve signal closed-loop control. The magnetic field is detected by the internal fluxgate sensor and integrated to the sensor output, ensuring high loop gain. The output of the integrator is connected to the built-in differential driver, generating a compensating current on the compensation coil; the compensation coil generates a corresponding magnetic field in the opposite direction, so that the drift is offset. The compensating current has a positive coefficient relationship with the external magnetic field: 12.2mA / mT, which will produce a voltage drop on the external current resistance; the integrated differential amplifier provides a fixed gain of 4V / V to this voltage drop, and finally a voltage is obtained on the pin, with a reference level REFIN proportional to the field strength:

[0066] V OUT [V]=B×G×R SHUNT ×G AMP

[0067] Coefficient relationship and fixed gain:

[0068] V OUT [V]=B[mT]×12.2mA / mT×R SHUNT [Ω]×4[V / V]

[0069] The TLV9002 is an operational amplifier designed for low power, low bias current, and small size, suitable for applications with high requirements for power consumption and size. This device uses a dual-channel structure, supports a wide voltage range of 1.8V to 5.5V, and can flexibly adapt to single or dual power supply systems. Its static current per channel is only 60μA, combined with an extremely low input bias current (5pA), making it a significant advantage in battery-powered or low-power systems.

[0070] In terms of miniaturization, the TLV9002 provides multiple compact packaging options, including SOIC-8, TSSOP-8, VSSOP-8, and micro packages (such as SOT-553, WSON), meeting the needs of space-limited devices. This design makes it particularly suitable for use in portable devices, industrial sensors, and embedded systems, while maintaining high performance and high reliability.

[0071] The low power consumption of the TLV9002 not only reflects in the static current, but also in its design of 1MHz unit gain bandwidth, which can provide stable amplification performance in medium frequency applications. In addition, its input offset voltage is maximally ±0.4mV, ensuring stability in high-precision measurement and signal conditioning. The built-in RFI and EMI suppression filter further enhances its anti-interference ability in complex electromagnetic environments.

[0072] The device design takes into account the high reliability requirement, so the sixth sensor is used as a redundant element for fault-tolerant calibration. When a sensor cannot work normally due to environmental influence or damage, the system can automatically call the data of the redundant sensor for correction, ensuring the stability of the measurement results.

[0073] Example 2: Signal acquisition and low-power processing

[0074] This example introduces the signal acquisition and processing flow.

[0075] In order to match the sensor data stream, a set of acquisition circuits is designed. In consideration of reducing equipment maintenance, low-power components are preferred in selection. The overall framework of the circuit is as follows: Figure 3The system is shown. In this system, the microcontroller unit (MCU) plays a core role, responsible for receiving and processing the magnetic flux density signal, managing data storage, controlling the indication circuit, and communicating with the Bluetooth Low Energy module. The external flash chip is used to store measurement results and various preset parameters, and the battery power supply and protection filter circuit provide sufficient and stable power supply for the system. The magnetic array works with the 6-channel analog-to-digital converter of the MCU to collect magnetic sensor voltage signals and invert current values by solving their coupling relationship. Finally, the measurement results including load phase currents, neutral line currents and ground leakage currents are transmitted through Bluetooth Low Energy wireless technology.

[0076] The design points and features of this circuit scheme are as follows: The MCU scheme uses STM32L0 series, which has multiple low-power modes and a minimum static current of only 0.23μA. This MCU not only has rich analog resources with 10 12-bit analog-to-digital conversion channels, but also can maintain a working current below 41μA at a sampling rate of 10ksps, making it very suitable for low-power applications. The storage chip uses Winbond Serial Peripheral Interface Bus storage chip W25Q01J, which has a capacity of 1024M-bit (128MB) and uses a standard Serial Peripheral Interface Bus interface for communication. This chip supports multiple operating modes, including page programming, sector erasing and block erasing, and has a built-in write protection mechanism to ensure data security and reliability.

[0077] STM32L031G6U6 is a high-performance low-power 32-bit ARM Cortex-M0+ microcontroller developed by STMicroelectronics, suitable for various embedded applications. The chip uses LQFP-48 packaging, operates at 32MHz, integrates 128KB Flash program memory, 20KB RAM and 6KB EEPROM, has rich peripheral functions including 12-bit ADC, multiple timers, communication interfaces (such as I2C, SPI, USART, LPUART, etc.), watchdog, RTC, DMA, etc. In terms of low power consumption, STM32L031G6U6 supports multiple low-power modes including standby mode, stop mode and sleep mode to adapt to different application scenarios. Its working voltage range is 1.8V to 3.6V, suitable for battery-powered or low-power systems. In addition, this microcontroller also has dynamic voltage regulation function, which can optimize power consumption in different running modes and prolong the device's battery life.

[0078] The 12-bit ADC of STM32L031G6U6 has 13 channels, supporting high-speed sampling and accurate measurement, suitable for sensor signal acquisition and data processing. Its rich communication interfaces enable flexible data interaction with other devices, suitable for industrial automation, smart home, remote monitoring and other fields. At the same time, the microcontroller also integrates a memory protection unit (MPU), enhancing the security and stability of the system. It provides complete development tools and documentation support, including data sheets, pinout diagrams, application examples and development guidelines, facilitating rapid design and debugging for developers. Its compact package and low power consumption make it an ideal choice for portable devices and small-sized systems.

[0079] W25Q01JVZEIQ is a 1GB serial NOR Flash memory chip produced by Winbond, using WSON-8 package, suitable for embedded systems sensitive to space and power consumption. The chip supports standard SPI interface, with a maximum clock frequency of 133MHz, providing efficient continuous read function, suitable for applications requiring high-speed data storage and reading. Its storage capacity is 1GB, composed of 512M bits of double-stack structure, supporting linear addressing, covering the complete 1G bit address range. Its storage unit is 256 bytes per page, with a maximum of 256 bytes of programmable data. Pages can be erased in blocks of 4KB, 32KB or 64KB, providing flexible storage management.

[0080] The chip has low power consumption characteristics, with a working voltage range of 2.7V to 3.6V, suitable for various power supply environments. In addition, it also supports various security functions such as write protection, power lock and OTP protection to enhance data security. In actual application, W25Q01JVZEIQ can be used for code storage, data storage, system configuration storage and other scenarios. Its compact package and high performance make it an ideal choice for embedded systems, Internet of Things devices, industrial control, consumer electronics and other fields.

[0081] The sensor signal is input to the 12-bit ADC of the STM32L031G6U6 microcontroller and converted at a sampling rate of 10ksps to obtain stable current data. To optimize power consumption, the device adopts a low-power management strategy. In the default state, the MCU enters standby mode, activates the sensor for short measurement every 50ms, and enters sleep state immediately after collecting data to reduce energy consumption. At the same time, the BLE5.0 wireless communication module adopts intermittent transmission mechanism, sends measurement data to the cloud server according to the set time interval (such as 10 seconds), realizing remote monitoring function.

[0082] Example 3: Current decoupling calculation method and calibration process

[0083] The embodiment introduces a current decoupling algorithm based on an electromagnetic field model.

[0084] The system establishes a magnetic field distribution matrix model through the Biot-Savart law, takes the current of each phase in the five-core cable as an unknown variable, and takes the magnetic field data obtained by the five measurement sensors as a known quantity. According to the basic theory of electromagnetic field, a specific magnetic field distribution pattern will be formed around the energized conductor, and this distribution characteristic can be quantitatively described. The mathematical expression is:

[0085]

[0086] In the formula: B is the magnetic induction intensity of a point in space;

[0087] μ0 is the magnetic permeability of vacuum;

[0088] i is the current passing through the wire;

[0089] R is the distance between the measurement point and the wire.

[0090] In the rectangular coordinate system, the center of the wire is located at the coordinate origin O, and the coordinates of the space point P are (x, y). According to formula (1), the magnetic induction intensity at point P can be expressed as:

[0091]

[0092] Decomposition can obtain two orthogonal components of the magnetic induction intensity:

[0093]

[0094] For a three-phase power supply system, three live wires and one neutral wire are arranged in a specific space. For example, Figure 2 , three live wires (a, B, C phases) are arranged in a regular triangle in the cross section, and the neutral wire N is located on the perpendicular bisector. The center distance between each wire is The direct determination formula is:

[0095]

[0096] Solve the inverse of the determination formula:

[0097]

[0098] The expansion of the coefficient K, i j The three-phase current, neutral line current and ground line current are represented in turn:

[0099]

[0100] The coefficient matrix K is related to the cable radius D, the distance d from the cable center to the core wire, and the deflection angle θ. Orthogonal decomposition is performed on B:

[0101] B j (t) = B x (t) cos θ j + B y (t) sin θ j

[0102] Specifically, the horizontal component of the magnetic induction intensity B x (t) is:

[0103]

[0104] The vertical component of the magnetic induction intensity B y (t) is:

[0105]

[0106] Further explanation, the magnetic field intensity follows the superposition theorem:

[0107] B = B A + B B + B C + B N + B E

[0108] Finally, through the Ampere loop theorem, the wire current can be inverted:

[0109]

[0110] The system is pre-set with a self-calibration mechanism, which can detect measurement errors caused by environmental changes and dynamically adjust the calculation coefficients to ensure that the measurement accuracy is stable at ±2%.

[0111] Example 4: Wireless data transmission and remote monitoring application

[0112] This embodiment introduces the docking scheme of the wireless data transmission and monitoring system.

[0113] RF-BM-4044B4 is a low-power Bluetooth (BLE) radio frequency module based on TI's CC2640R2FRSM chip, designed for short-range wireless communication. The module uses the 2.4GHz ISM frequency band, supports GFSK modulation, has 40 channels and a channel spacing of 2MHz, and is suitable for various wireless communication scenarios. Its operating voltage range is 1.8V to 3.8V, supports low-power operation, and is suitable for battery-powered devices.

[0114] The RF-BM-4044B4 module is built-in with a 32-bit ARM Cortex-M3 processor, which has rich peripheral functions including UART, SPI, I2C, ADC interfaces, supports serial pass-through protocol and BLE protocol stack, and is convenient for data interaction with external devices. The module size is 8mm x 8mm, and adopts SMT packaging, which is convenient for integration into compact devices. In addition, the module supports Bluetooth 5.0 standard, has high communication rate and long transmission distance, and is suitable for smart home, industrial control, health care, sports measurement and other fields.

[0115] In terms of power consumption, the RF-BM-4044B4 adopts intermittent working mode and can run in low power consumption mode, further prolonging the endurance time of the device. Its receiving sensitivity is as high as -97dBm, and the transmission power can be adjusted to -21dBm to +2dBm, with good anti-interference ability. The module also supports multiple antenna forms, which can be optimized according to specific application scenarios. The RF-BM-4044B4 is suitable for wireless communication solutions that require low power consumption, small size and high integration, and is an ideal wireless module choice for Internet of Things (IoT) devices.

[0116] In practical application, each measuring device sends data through wireless broadcast, and the cloud server or local monitoring system receives and stores the real-time current data of the load end. In the monitoring platform, the system analyzes the trend of the measurement data, can automatically identify load imbalance, abnormal power consumption, leakage problems and other situations, and generates warning information, improving the intelligent scheduling capability of the virtual power plant load side. For different application scenarios, users can customize the data upload frequency, such as high frequency mode (1 second) for fault detection and low frequency mode (10 minutes) for long-term trend monitoring, to optimize energy consumption and response speed.

[0117] Example 5: Environmental adaptability and application expansion

[0118] This example introduces the applicability of the device under different environmental conditions.

[0119] The system supports working temperature of -20℃~80℃, and is suitable for extreme environments such as power facilities in cold regions or high-temperature industrial sites. The shell adopts waterproof and dustproof design to ensure the long-term stable operation of the device in humid and severely polluted environments.

[0120] The device design is compact and small in size, making it easy to adapt to various installation environments without the need for complex installation procedures or additional space. The compact design allows the device to be easily installed in narrow spaces such as cable wells, power distribution cabinets, etc., without the need for large-scale modification of existing facilities. With a buckle-type fixing structure, the operator can quickly complete the installation alone, greatly improving the installation efficiency. This design not only saves installation time, but also reduces potential damage to cables and surrounding facilities during installation. The device is compatible with three-phase four-wire and three-phase five-wire cables, allowing it to adapt to different power system configurations. This compatibility allows the device to be used in a variety of application scenarios without the need for different measurement equipment for different specifications of cables.

[0121] With the sensor redundancy design, the reliability and fault tolerance of the system are improved. Redundant sensors are designed in the ring-shaped magnetic sensor array, so that even if a sensor fails or is disturbed, the system can still make accurate measurements through the data of other sensors. This redundant design ensures the stability and reliability of the measurement results. The system can monitor the output data of the sensors in real time, automatically detect sensor failures or abnormal conditions, and enable redundant sensors for calibration. This automatic calibration mechanism further improves the robustness of the system, ensuring high-precision measurement in complex environments. The device can accurately detect leakage current and load imbalance. By analyzing the data of multiple sensors, the system can quickly identify the presence of leakage current and provide accurate current distribution information when the load is unbalanced. This ability is crucial for preventing power accidents and optimizing power system operation.

Claims

1. A virtual power plant load end three-phase five-core cable non-contact current measurement device, characterized in that, It comprises: a ring-shaped magnetic sensor array (1) composed of 6 magnetic fluxgate sensors evenly arranged on the periphery of the cable to be measured, wherein 5 sensors correspond to the magnetic field measurement of three-phase live lines (L1-L3), neutral line (N) and ground line (PE) respectively, and the 6th sensor is a redundant sensor for real-time calibration and fault tolerance; a buckle type fixing structure (2) for fixing the magnetic fluxgate sensors on the surface of the cable (3) and ensuring the concentricity of each sensor with the cable; a signal acquisition and processing unit (4) electrically connected with the ring-shaped magnetic sensor array (1) for acquiring and processing the magnetic field signals; a wireless communication module (5) connected with the signal acquisition and processing unit (4) for remotely transmitting the measurement data to the monitoring system.

2. The virtual power plant load end three-phase five-core cable non-contact current measurement device according to claim 1, characterized in that, The magnetic fluxgate sensor is a DRV425 type magnetic fluxgate sensor evenly arranged on a ring-shaped PCB board at an interval of 60°.

3. The virtual power plant load end three-phase five-core cable non-contact current measurement device according to claim 1, characterized in that, The buckle type structure is made of ABS engineering plastic with an inner diameter of 6 mm.

4. The virtual power plant load end three-phase five-core cable non-contact current measurement device according to claim 1, characterized in that, The signal acquisition and processing circuit comprises: a main control chip for executing current decoupling algorithm; a low-noise amplification circuit with input end connected with the output end of each magnetic fluxgate sensor; a 12-bit ADC sampling circuit with input end connected with the output end of the low-noise amplification circuit and output end connected with the ADC interface of the main control chip.

5. The virtual power plant load end three-phase five-core cable non-contact current measurement device according to claim 4, characterized in that, The signal acquisition and processing circuit further comprises: a temperature compensation circuit integrated in the low-noise amplification circuit for eliminating the temperature drift of the DRV425 sensor; a digital filtering algorithm running in the main control chip for suppressing 50Hz power frequency interference.

6. The virtual power plant load end three-phase five-core cable non-contact current measurement device according to claim 4, characterized in that, The sampling rate of the 12-bit ADC sampling circuit is 10kSPS, and the dynamic range covers the measured cable current of 0.1mA-1000A.

7. The virtual power plant load end three-phase five-core cable non-contact current measurement device according to claim 1, characterized in that, The wireless communication module is a RF-BM-4044B4 type BLE5.0 module supporting multi-device networking.

8. A method of measuring current based on the device of any one of claims 1-7, characterized by, It comprises the following steps: S1. Sensor array installation: the buckle type fixing structure (2) is fitted on the cable (3), each sensor is installed on the cable (3) through the buckle type fixing structure (2), and the concentricity of each magnetic fluxgate sensor with the cable is ensured, and the initial coefficient matrix K is calibrated; S2. Magnetic field signal acquisition: the ring-shaped magnetic sensor array (1) synchronously acquires the magnetic field signals around the cable, which are amplified, filtered and converted into digital signals by the signal acquisition and processing unit (4); S3. Current decoupling calculation: the main control chip executes the following algorithm: S3.

1. A magnetic field distribution matrix model of five-core cable is established based on the Biot-Savart law: wherein is the current vector of the respective wire, is the theoretical magnetic field distribution matrix; μ0is the vacuum permeability; S3.

2. The currents of each conductor are decoupled by inverse matrix operation: S4. Redundancy check: compare the measured value of the 6th sensor with the theoretical value, and trigger the calibration program when the deviation exceeds 5%; S5. Data wireless transmission: upload the current data and device status information to the monitoring terminal.

9. The current measurement method according to claim 8, characterized in that, Step (3) further comprises a dynamic compensation algorithm: Real-time monitoring of ambient temperature, correction of sensor gain through temperature compensation circuit; When the cable position deviation is detected, the parameters of matrix K are automatically updated.

10. The current measurement method of claim 8, wherein: In step S4, the trigger threshold of redundancy check is 5%, and the redundant sensor is used to replace the abnormal channel data during calibration.

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