On-line real-time monitoring system for flow velocity and temperature of transformer oil body

Abstract

The utility model discloses an on-line real-time monitoring system for flow velocity and temperature of a transformer oil body, which relates to the field of transformer state detection and comprises a terminal node, a gateway, a cloud server and an application layer interface. The terminal node is composed of sensor equipment integrated with a BLE communication module, and the sensor equipment measures the flow velocity and the temperature and sends data to the gateway through a BLE protocol; the gateway receives the data sent by the terminal node and transmits the data to the cloud server for storage, processing and analysis; according to the utility model, the detection and monitoring efficiency of the state of the transformer can be greatly improved, and the coping capability of the transformer to various abnormal working conditions can be improved.

Description

Technical Field

[0001] The utility model relates to the field of transformer state detection, in particular to an online real-time monitoring system for transformer oil flow rate and temperature. Background Art

[0002] In modern power systems, substation transformers play a vital role. As the core equipment of the power grid, its status monitoring and fault diagnosis are directly related to the power supply quality of the power system. However, with the aging of equipment and the complexity of operation, substation transformers may have some equipment problems during long-term uninterrupted operation, posing a threat to the normal operation of the entire power grid. Therefore, it is of great significance to carry out status monitoring and fault diagnosis of substation transformers.

[0003] In daily transformer inspection and maintenance, common faults of substation transformers are mainly reflected in winding faults, transformer oil faults, switch faults, cooling system faults, external short circuit faults and grounding faults. These faults cause the transformer's energy efficiency to decline, overheating, leakage problems, and even fire hazards, posing a serious threat to the safe supply of power in the power system. Therefore, in view of the importance and common faults of transformers in substations, studying an efficient and fast transformer status monitoring and fault diagnosis technology has become a research topic for many scholars.

[0004] At present, a lot of research has been done on transformer status monitoring and fault diagnosis. By installing measuring sensors and combining the parameter change rules of the monitored equipment in different states, a comprehensive online monitoring device is developed to grasp the dynamics of the equipment in real time, and to provide early warning of its inherent defects and fault evolution to avoid further deterioration of the fault. Technologies such as oil gas monitoring, partial discharge monitoring, vibration monitoring and temperature monitoring have been widely used.

[0005] As an important indicator for judging the working status of the transformer, the cooling oil flow rate can directly reflect a series of cooling system abnormalities such as oil flow circuit blockage, oil pump failure, and heat dissipation to prevent transformer overheating failure. However, in actual operation, the transformer cooling oil flow rate has long been in a passive situation without corresponding monitoring means. This is determined by the special operating environment of the transformer. On the one hand, the transformer has very high requirements for sealing, and a non-contact measurement method must be used, and the transformer cooling oil is an insulating fluid. Therefore, the most commonly used contact turbine flowmeter for pipeline fluid measurement and the electromagnetic induction flowmeter for measuring conductive liquids cannot be used as a measurement method. In addition to the limitations of the detection method, on the other hand, the transformer often works in a complex strong magnetic environment, the cooling oil pipe wall thickness is large, and the flow rate measurement equipment used under general conditions often fails, so the reliability and stability of the monitoring equipment are also facing great challenges.

[0006] At present, for the measurement of transformer cooling oil flow rate, although some researchers have tried some theoretical measurement methods, such as establishing a functional relationship between oil flow rate and temperature based on the characteristics of oil temperature, and obtaining a correlation model between transformer oil flow rate and temperature. However, these theoretical methods lack practical experience and it is difficult to ensure the stability and accuracy of the measuring equipment in the complex working environment of the transformer. In addition, after on-site investigation of the substation workshop, the transformer maintenance and status monitoring methods are still relatively backward, relying on long-term manual repeated measurements, and urgently need an automated intelligent real-time monitoring system, but there is currently a lack of such systems and methods for the operating status of transformers. Utility Model Content

[0007] In order to solve the above problem, a non-contact ultrasonic measurement method is used to measure the flow rate of the transformer cooling oil pipeline. Combined with the Internet of Things technology, an integrated online real-time monitoring sensor system for transformer flow rate and temperature is proposed. The system method proposed in this utility model can greatly improve the detection and monitoring efficiency of the transformer status and improve the transformer's ability to respond to various abnormal working conditions.

[0008] An online real-time monitoring system for transformer oil flow rate and temperature, comprising: a terminal node, a gateway, a cloud server, and an application layer interface;

[0009] The terminal node consists of a sensor device with an integrated BLE communication module. The sensor device measures flow rate and temperature and sends the data to the gateway via the BLE protocol.

[0010] The gateway receives the data sent by the terminal nodes and transmits it to the cloud server for storage, processing and analysis;

[0011] The application layer interface is used for users to monitor and manage data;

[0012] The terminal node includes a flow rate and temperature sensor module and a Bluetooth data acquisition board;

[0013] The flow rate and temperature sensing module includes a flow rate and temperature sensing device having an RS485 interface;

[0014] The Bluetooth data acquisition board includes an MCU radio frequency module, a voltage-stabilized power supply module, an RS485 interface module, and a debugging interface module;

[0015] The voltage-stabilized power supply module is used to supply power to the MCU radio frequency module and the RS485 interface module; the RS485 interface module is used to connect to the RS485 interface of the flow rate and temperature sensor device for signal transmission; the MCU radio frequency module and the RS485 interface module are connected via a serial port for processing and transmitting radio frequency signals;

[0016] Furthermore, the flow rate and temperature sensing device adopts a TUF-2000B ultrasonic flow meter.

[0017] Furthermore, the MCU radio frequency module adopts the nRF52840 Bluetooth radio frequency chip U1.

[0018] Furthermore, the RS485 interface module adopts the MAX3485ESA chip U2.

[0019] Furthermore, the TUF-2000B ultrasonic flow meter supplies power to the voltage stabilizing power supply module.

[0020] Furthermore, the voltage-stabilized power supply module includes a linear regulator U5, a resistor R11, a resistor R12, a capacitor C4, a capacitor C5, and a 2-pin terminal U4, the VIN interface of U5 is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the EN interface of U5 and one end of the resistor R12, the other end of the resistor R12 is connected to the 8th pin of the chip U1, the VOUT interface of U5 is connected to one end of the capacitor C5, the other end of the capacitor C5 is grounded, and 3.3V power is provided to the outside by the VOUT interface of U5, the 1st pin of U4 is connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the 2nd pin of U4 and the VIN interface of U5, and the 1st pin of U4 is grounded.

[0021] Further, the debugging interface module includes a universal asynchronous receiver and transmitter and a virtual serial port; the universal asynchronous receiver and transmitter has 4 pins, one pin is connected to the 3.3V power supply, one pin is grounded, one TXD pin, and one RXD pin, wherein the TXD pin is connected to the 16th pin of U1, and the RXD pin is connected to the 14th pin of U1; the virtual serial port has 4 pins, one pin is connected to the 3.3V power supply, one pin is grounded, one SWDCLK pin, and one SWDIO pin, wherein the SWDCLK pin is connected to the 39th pin of U1, and the SWDIO pin is connected to the 37th pin of U1;

[0022] The debugging interface module also includes a reset button, two signal lights LED1 and LED2, resistor R2, capacitor C3, resistor R8, resistor R9, and resistor R10; the reset button is connected in parallel with capacitor C3, one end of capacitor C3 is grounded, the other end of capacitor C3 is connected to resistor R2 and pin 26 of U1, and the other end of resistor R2 is connected to a 3.3V power supply; one end of resistor R9 is connected to a 3.3V power supply, the other end of resistor R9 is connected to the positive electrode of signal light LED1, and the negative electrode of LED1 is connected to pin 33 of U1; one end of resistor R10 is connected to a 3.3V power supply, the other end of resistor R10 is connected to the positive electrode of signal light LED2, and the negative electrode of LED2 is connected to pin 35 of U1.

[0023] Furthermore, the RS485 interface module includes a MAX3485ESA chip U2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7. One end of the resistor R3 is connected to the 14th pin of U1, and the other end of the resistor R3 is connected to the 1st pin of U2. One end of the resistor R4 is connected to the 15th pin of U1, and the other end of the resistor R4 is connected to the 2nd and 3rd pins of U2. One end of the resistor R5 is connected to the 16th pin of U1, and the other end of the resistor R5 is connected to the 4th pin of U2. One end of the resistor R6 is connected to a 3.3V power supply, and the other end of the resistor R6 is connected to the 8th pin of U2. One end of the resistor R7 is connected to the 7th pin of U2, and the other end of the resistor R7 is connected to the 6th pin of U2.

[0024] Furthermore, the MCU RF module includes: nRF52840 Bluetooth RF chip U1, resistor R1, inductor L1, crystal oscillator X1, capacitor C1, capacitor C2, pin 11 of U1 is connected to one end of the crystal oscillator X1 and one end of the capacitor C1, pin 13 of U1 is connected to the other end of the crystal oscillator X1 and one end of the capacitor C2, the other end of the capacitor C1 is grounded, the other end of the capacitor C2 is grounded, pin 24 of U1 is grounded, one end of the inductor L1 is connected to pin 23 of U1 and pin 19 of U1, the other end of the inductor L1 is connected to pin 25 of U1, one end of the resistor R1 is connected to pin 19 of U1, the other end of the resistor R1 is connected to a 3.3V power supply, and pin 5 of U1 is grounded.

[0025] The beneficial effects brought by the technical solution provided by the utility model are:

[0026] The utility model provides a wireless monitoring system composed of terminal nodes, gateways, cloud servers, and application layer interfaces. It uses a non-contact ultrasonic measurement method to measure the flow rate of transformer cooling oil pipelines. Combined with the Internet of Things technology, it proposes an integrated online real-time monitoring sensor system for transformer flow rate and temperature. It can greatly improve the detection and monitoring efficiency of transformer status and improve the transformer's ability to respond to various abnormal working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a topological structure of an online real-time monitoring system for transformer oil flow velocity and temperature proposed in the embodiment of the utility model;

[0028] Figure 2 It is the hardware circuit of the Bluetooth data acquisition board of the embodiment of the utility model;

[0029] Figure 3 It is a flow chart of the working principle of the embodiment of the utility model;

[0030] Figure 4 It is the measurement result of the installation test of the entire system of the embodiment of the utility model. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the utility model clearer, the implementation mode of the utility model will be further described below in conjunction with the accompanying drawings.

[0032] The topology structure of a transformer oil flow rate and temperature online real-time monitoring system proposed in the embodiment of the utility model is as follows Figure 1 As shown, it includes: terminal nodes, gateways, cloud servers, and application layer interfaces.

[0033] The terminal node is composed of sensor devices integrated with BLE communication modules. The sensor devices measure flow rate and temperature. After completing the temperature and flow rate collection, the terminal device will broadcast data packets as a BLE beacon device. The BLE gateway device will continuously scan the BLE data packets being transmitted and send the data to the gateway through the BLE protocol; then push the data to the MQTT server through 4G, WIFI and other network access settings to realize cloud storage of data.

[0034] The gateway is a bridge connecting the sensor nodes and the upper network. It has more powerful processing and communication capabilities. It can receive data sent by the sensor nodes and transmit it to the cloud or other remote servers.

[0035] This embodiment uses a Bluetooth gateway device to connect the Bluetooth terminal device with the upper network, receive the data packets of the terminal node and push them to the server. Since the terminal node adopts a low-power Bluetooth communication method, a Bluetooth gateway device with a network access configuration is selected. The Bluetooth gateway device processes and parses the received Bluetooth data, converts the Bluetooth protocol into other network protocols, and realizes data intercommunication and exchange. In addition, the Bluetooth gateway device can also manage the connection of multiple Bluetooth devices, and provide corresponding data processing and routing functions to realize interconnection between devices. By connecting to the Internet, the Bluetooth gateway device can also realize remote monitoring and control of the terminal node, allowing users to manage the terminal node data through the Internet.

[0036] The EW-DTU series Bluetooth gateway device used in this embodiment supports multiple network access methods such as BLE to 4G, RJ45, and WIFI. The coverage radius reaches 300m, and the upper limit of the number of terminal devices scanned and monitored is 300. It can realize the centralized reception of data from multiple terminal nodes in the same area. For the transmission information of different terminal nodes, the terminal node messages to be received can be filtered out by the prefix of the broadcast data packet. These messages can be distinguished by the terminal's broadcast name and device MAC address. In addition, the gateway includes supporting network tools, supports user-defined network access modes, supports online viewing and historical query of cloud data, and supports exporting historical data with timestamps into text format.

[0037] The sensor data will be sent to the cloud server for storage, processing and analysis. The cloud server can provide data storage, remote monitoring, data analysis and other functions, providing data services for users and applications.

[0038] The role of the application layer interface is to enable users and applications to use the data in the sensor network, including mobile apps, web interfaces, etc., so that users can easily monitor and manage the data in the sensor network.

[0039] The terminal node includes a flow rate and temperature sensor module and a Bluetooth data acquisition board. The flow rate and temperature sensor module includes a flow rate and temperature sensor device with an RS485 interface. The Bluetooth data acquisition board includes an MCU radio frequency module, a voltage-stabilized power supply module, an RS485 interface module, and a debugging interface module. The hardware circuit of the Bluetooth data acquisition board is as follows: Figure 2 shown.

[0040] The voltage-stabilized power supply module is used to supply power to the MCU radio frequency module and the RS485 interface module; the RS485 interface module is used to connect to the RS485 interface of the flow rate and temperature sensor device for signal transmission; the MCU radio frequency module and the RS485 interface module are connected via a serial port for processing and transmitting radio frequency signals.

[0041] The flow rate and temperature sensing equipment uses TUF-2000B ultrasonic flowmeter. The measurement error of TUF-2000B flowmeter is ±%1, with 1 4~20mA current output, 3 4~20mA current input, and an accuracy of 0.1%. It can collect temperature, pressure, liquid level and other signals, and can be connected to a three-wire PT100 platinum resistor, which is conducive to the integration of flow rate and temperature sensing equipment. In addition, the equipment also has an isolated RS485 serial interface, supports Modbus and other protocols, and is convenient for the terminal control device to read and write sensor information. TUF-2000B ultrasonic flowmeter supplies power to the voltage stabilized power supply module.

[0042] The MCU RF module uses the nRF52840 Bluetooth RF chip U1, which sends commands and receives data to TUF-2000B according to the Modbus protocol. nRF52840 is a Bluetooth RF chip with excellent performance launched by Nordic. It integrates a 64MHz Arm processor core, supports the Bluetooth 5.0 protocol, contains rich on-chip resources, and has the advantages of low power consumption and high receiving sensitivity.

[0043] The RS485 interface module uses the MAX3485ESA chip U2.

[0044] The voltage-stabilized power supply module includes a linear voltage regulator U5, a resistor R11, a resistor R12, a capacitor C4, a capacitor C5, and a 2-pin terminal U4. U5 has 5 pins, the first pin of U5 is a VIN interface, the second pin of U5 is a GND interface, the third pin of U5 is an EN interface, the fourth pin of U5 is an NC interface, and the fifth pin of U5 is a VOUT interface. The VIN interface of U5 is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the EN interface of U5 and one end of the resistor R12, the other end of the resistor R12 is connected to the 8th pin of the chip U1, the VOUT interface of U5 is connected to one end of the capacitor C5, the other end of the capacitor C5 is grounded, and 3.3V power is provided to the outside by the VOUT interface of U5, the first pin of U4 is connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the second pin of U4 and the VIN interface of U5, and the first pin of U4 is grounded. The 2-pin terminal U4 is used to connect an external power supply to power the voltage-stabilized power supply module. In this embodiment, the linear regulator U5 of the voltage-stabilized power supply module adopts ADP150AUJZ, and the 2-pin terminal U4 adopts DB127S-5.08-2P-GN.

[0045] The debugging interface module includes a universal asynchronous receiver and transmitter and a virtual serial port; the universal asynchronous receiver and transmitter has 4 pins, one pin connected to the 3.3V power supply, one pin connected to the ground, one TXD pin, and one RXD pin, wherein the TXD pin is connected to the 16th pin of U1, and the RXD pin is connected to the 14th pin of U1; the virtual serial port has 4 pins, one pin connected to the 3.3V power supply, one pin connected to the ground, one SWDCLK pin, and one SWDIO pin, wherein the SWDCLK pin is connected to the 39th pin of U1, and the SWDIO pin is connected to the 37th pin of U1.

[0046] The debugging interface module also includes a reset button, two signal lights LED1 and LED2, a resistor R2, a capacitor C3, a resistor R8, a resistor R9, and a resistor R10; the reset button is connected in parallel with the capacitor C3, one end of the capacitor C3 is grounded, the other end of the capacitor C3 is connected to the resistor R2 and the 26th pin of U1, and the other end of the resistor R2 is connected to a 3.3V power supply; one end of the resistor R9 is connected to a 3.3V power supply, the other end of the resistor R9 is connected to the positive electrode of the signal light LED1, and the negative electrode of LED1 is connected to the 33rd pin of U1; one end of the resistor R10 is connected to a 3.3V power supply, the other end of the resistor R10 is connected to the positive electrode of the signal light LED2, and the negative electrode of LED2 is connected to the 35th pin of U1. In this embodiment, the debugging interface module also includes a power light POWER1, the positive electrode of the power light is connected to one end of the resistor R8, the negative electrode of the power light is grounded, and the other end of the resistor R8 is connected to a 3.3V power supply.

[0047] The RS485 interface module includes a MAX3485ESA chip U2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7. One end of the resistor R3 is connected to the 14th pin of U1, and the other end of the resistor R3 is connected to the 1st pin of U2. One end of the resistor R4 is connected to the 15th pin of U1, and the other end of the resistor R4 is connected to the 2nd and 3rd pins of U2. One end of the resistor R5 is connected to the 16th pin of U1, and the other end of the resistor R5 is connected to the 4th pin of U2. One end of the resistor R6 is connected to a 3.3V power supply, and the other end of the resistor R6 is connected to the 8th pin of U2. One end of the resistor R7 is connected to the 7th pin of U2, and the other end of the resistor R7 is connected to the 6th pin of U2. The 6th and 7th pins of the MAX3485ESA chip U2 are respectively connected to two pins of the 2-pin terminal U3, providing a 485 communication interface and external device connection. Among them, the 2-pin terminal U3 adopts DB127S-5.08-2P-GN.

[0048] The MCU RF module includes: nRF52840 Bluetooth RF chip U1, resistor R1, inductor L1, crystal oscillator X1, capacitor C1, capacitor C2, pin 11 of U1 is connected to one end of the crystal oscillator X1 and one end of the capacitor C1, pin 13 of U1 is connected to the other end of the crystal oscillator X1 and one end of the capacitor C2, the other end of the capacitor C1 is grounded, the other end of the capacitor C2 is grounded, pin 24 of U1 is grounded, one end of the inductor L1 is connected to pin 23 of U1 and pin 19 of U1, the other end of the inductor L1 is connected to pin 25 of U1, one end of the resistor R1 is connected to pin 19 of U1, the other end of the resistor R1 is connected to a 3.3V power supply, and pin 5 of U1 is grounded.

[0049] In this embodiment, the resistors R1, R6, and R11 are 0R, and the zero ohm resistor is also called a jumper resistor, which is a special resistor. R2 is 10k, and R3, R4, R5, R7, R8, R9, R10, and R12 are 1k. The inductor L1 is 10uH, the capacitors C1 and C2 are 12pF, and C3, C4, and C5 are 0.1uF. The frequency of the crystal oscillator X1 is 32.768kHz.

[0050] The terminal node mainly includes two tasks: data collection and sending, and these two tasks are triggered by two timers respectively.

[0051] Data acquisition task: When new flow rate or temperature information needs to be obtained, a data read command needs to be sent to TUF-2000B through the serial port in the format. It should be noted that since MAX3485 can only realize half-duplex transmission, a certain delay is required between two commands to ensure that the previous data packet is correctly received. After sending the command, MAX3485 immediately switches to the receiving state. When the data packet is received, the serial port interrupt of nRF52840 will be triggered. The serial port interrupt receives 1 byte of information each time. When 9 serial port interrupts are entered cumulatively, the data packet packet is received.

[0052] Data transmission task: The device broadcasts data packets periodically and sends the information to the gateway. The task of the data transmission task is to parse the raw data obtained in the data acquisition task. Then initialize the Bluetooth broadcast, add prefixes to the parsed flow rate and temperature information in hexadecimal format, and package them into a Bluetooth broadcast packet format of ten data bytes and send them out.

[0053] Timer 1 (data collection) task: The interrupt interval of Timer 1 can be set as required, and the default is 1s. When the Timer 1 interrupt is triggered, the task flag FLAG_1 of the data collection task is set to 1, and the task flag will be set to 0 after the control instruction is sent.

[0054] Timer 2 (data transmission) task: The interrupt interval of Timer 2 can be set according to the monitoring data update frequency requirement, and the default is 2s. When the Timer 2 interrupt is triggered, the task flag FLAG_2 of the data transmission task is set to 1, and the task flag will be set to 0 after the Bluetooth broadcast is sent.

[0055] Designed according to the system data acquisition task, data transmission task, timer and serial port interrupt function. The working principle flow chart of the utility model is as follows Figure 3 shown.

[0056] Test Results

[0057] The solution of the utility model is used for actual measurement. The inner diameter of the cooling oil pipeline is 200mm, the wall thickness is 10mm, and the flow velocity probe is installed using the V method. After 5 hours of continuous measurement, the measurement results are as follows: Figure 4 As shown. Figure 4 It can be seen that the terminal equipment is in good operating condition, the node data communication is stable, and the measurement results are stable and accurate.

[0058] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A transformer oil flow rate and temperature online real-time monitoring system, characterized in that: include: Terminal nodes, gateways, cloud servers, and application layer interfaces; The terminal node consists of a sensor device with an integrated BLE communication module. The sensor device measures flow rate and temperature and sends the data to the gateway via the BLE protocol. The gateway receives the data sent by the terminal nodes and transmits it to the cloud server for storage, processing and analysis; The application layer interface is used for users to monitor and manage data; The terminal node includes a flow rate and temperature sensor module and a Bluetooth data acquisition board; The flow rate and temperature sensing module includes a flow rate and temperature sensing device having an RS485 interface; The Bluetooth data acquisition board includes an MCU radio frequency module, a voltage-stabilized power supply module, an RS485 interface module, and a debugging interface module; The voltage-stabilized power supply module is used to supply power to the MCU radio frequency module and the RS485 interface module; the RS485 interface module is used to connect to the RS485 interface of the flow rate and temperature sensor device for signal transmission; the MCU radio frequency module and the RS485 interface module are connected via a serial port for processing and transmitting radio frequency signals.

2. The online real-time monitoring system for transformer oil flow rate and temperature according to claim 1 is characterized in that: The flow rate and temperature sensing equipment uses TUF-2000B ultrasonic flow meter.

3. The online real-time monitoring system for transformer oil flow rate and temperature according to claim 1 is characterized in that: The MCU RF module uses the nRF52840 Bluetooth RF chip U1.

4. A transformer oil flow rate and temperature online real-time monitoring system according to claim 3, characterized in that: The RS485 interface module uses the MAX3485ESA chip U2.

5. The online real-time monitoring system for transformer oil flow rate and temperature according to claim 2 is characterized in that: The TUF-2000B ultrasonic flow meter supplies power to the voltage regulated power supply module.

6. The online real-time monitoring system for transformer oil flow rate and temperature according to claim 3 is characterized in that: The voltage-stabilized power supply module includes a linear voltage regulator U5, a resistor R11, a resistor R12, a capacitor C4, a capacitor C5, and a 2-pin terminal U4. The VIN interface of U5 is connected to one end of the resistor R11, and the other end of the resistor R11 is connected to the EN interface of U5 and one end of the resistor R12. The other end of the resistor R12 is connected to the 8th pin of the chip U1. The VOUT interface of U5 is connected to one end of the capacitor C5, and the other end of the capacitor C5 is grounded. 3.3V power is provided to the outside by the VOUT interface of U5. The first pin of U4 is connected to one end of the capacitor C4, and the other end of the capacitor C4 is connected to the second pin of U4 and the VIN interface of U5. The first pin of U4 is grounded.

7. The online real-time monitoring system for transformer oil flow rate and temperature according to claim 3 is characterized in that: The debugging interface module includes a universal asynchronous receiver and transmitter and a virtual serial port; the universal asynchronous receiver and transmitter has 4 pins, one pin connected to the 3.3V power supply, one pin connected to the ground, one TXD pin, and one RXD pin, wherein the TXD pin is connected to the 16th pin of U1, and the RXD pin is connected to the 14th pin of U1; the virtual serial port has 4 pins, one pin connected to the 3.3V power supply, one pin connected to the ground, one SWDCLK pin, and one SWDIO pin, wherein the SWDCLK pin is connected to the 39th pin of U1, and the SWDIO pin is connected to the 37th pin of U1; The debugging interface module also includes a reset button, two signal lights LED1 and LED2, resistor R2, capacitor C3, resistor R8, resistor R9, and resistor R10; the reset button is connected in parallel with capacitor C3, one end of capacitor C3 is grounded, the other end of capacitor C3 is connected to resistor R2 and pin 26 of U1, and the other end of resistor R2 is connected to a 3.3V power supply; one end of resistor R9 is connected to a 3.3V power supply, the other end of resistor R9 is connected to the positive electrode of signal light LED1, and the negative electrode of LED1 is connected to pin 33 of U1; one end of resistor R10 is connected to a 3.3V power supply, the other end of resistor R10 is connected to the positive electrode of signal light LED2, and the negative electrode of LED2 is connected to pin 35 of U1.

8. The online real-time monitoring system for transformer oil flow rate and temperature according to claim 4 is characterized in that: The RS485 interface module includes a MAX3485ESA chip U2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7. One end of the resistor R3 is connected to the 14th pin of U1, and the other end of the resistor R3 is connected to the 1st pin of U2. One end of the resistor R4 is connected to the 15th pin of U1, and the other end of the resistor R4 is connected to the 2nd and 3rd pins of U2. One end of the resistor R5 is connected to the 16th pin of U1, and the other end of the resistor R5 is connected to the 4th pin of U2. One end of the resistor R6 is connected to a 3.3V power supply, and the other end of the resistor R6 is connected to the 8th pin of U2. One end of the resistor R7 is connected to the 7th pin of U2, and the other end of the resistor R7 is connected to the 6th pin of U2.

9. The transformer oil flow rate and temperature online real-time monitoring system according to claim 3 is characterized in that: The MCU RF module includes: nRF52840 Bluetooth RF chip U1, resistor R1, inductor L1, crystal oscillator X1, capacitor C1, capacitor C2, pin 11 of U1 is connected to one end of the crystal oscillator X1 and one end of the capacitor C1, pin 13 of U1 is connected to the other end of the crystal oscillator X1 and one end of the capacitor C2, the other end of the capacitor C1 is grounded, the other end of the capacitor C2 is grounded, pin 24 of U1 is grounded, one end of the inductor L1 is connected to pin 23 of U1 and pin 19 of U1, the other end of the inductor L1 is connected to pin 25 of U1, one end of the resistor R1 is connected to pin 19 of U1, the other end of the resistor R1 is connected to a 3.3V power supply, and pin 5 of U1 is grounded.

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