Ultrasonic oil level monitoring device for oil tank

Abstract

This invention provides an ultrasonic oil level monitoring device for oil conservator tanks, belonging to the field of oil level monitoring technology. Its composite material high-power ultrasonic probe, through optimized acoustic matching layer and backing structure, significantly improves transmission efficiency and receiving sensitivity, enhances echo signal-to-noise ratio, and provides clear and stable signals, ensuring measurement accuracy from the hardware source and effectively reducing misjudgments caused by noise interference. The multi-frequency scanning adaptive measurement mechanism can identify interference conditions such as oil mist, foam, and oil surface sloshing in real time, automatically switching to the optimal operating frequency to suppress false echoes and data jumps, maintaining stable measurement even in harsh environments, solving the industry problem of poor adaptability of traditional single-frequency technology. The power adaptive modulation technology achieves unsaturated operation at close range and distortion-free operation at long range, controlling measurement errors within a reasonable range across the entire measurement range, improving accuracy compared to traditional technologies and meeting the high-precision oil level monitoring requirements of transformer oil conservator tanks.

Description

Technical Field

[0001] This invention belongs to the field of oil level monitoring technology, and specifically relates to an ultrasonic oil level monitoring device for oil storage tanks. Background Technology

[0002] In power systems, oil-immersed transformers are crucial transmission and transformation equipment, and their safe and stable operation directly affects the reliability of the entire power grid. The oil conservator, as a key component of the transformer, primarily compensates for the volume expansion and contraction of transformer oil due to temperature changes, maintains stable internal oil pressure, and ensures insulation and heat dissipation performance. Oil level is a core monitoring parameter for the oil conservator's operating status. Accurate, real-time, and stable oil level data can promptly reflect whether the transformer has faults such as oil leakage, oil shortage, or abnormal oil level, serving as an important basis for transformer condition-based maintenance and safety early warning.

[0003] Current oil level detection technologies for oil conservator tanks mainly include mechanical float / float type, capacitive type, magnetostrictive type, and traditional single-frequency ultrasonic type. Mechanical float / float type has a simple structure and low cost, but suffers from drawbacks such as mechanical wear, jamming, low measurement accuracy, and inability to transmit data remotely, making it difficult to meet the online monitoring needs of smart grids. Capacitive oil level gauges are susceptible to interference from oil quality, temperature, and impurities, resulting in poor long-term operational stability and a large maintenance workload. Magnetostrictive oil level gauges offer high accuracy, but their complex structure, high cost, and weak resistance to electromagnetic interference limit their application in substations with strong electromagnetic environments. Traditional single-frequency ultrasonic oil level gauges calculate oil level height based on the round-trip time of sound waves, offering advantages such as non-contact operation, no mechanical wear, and convenient installation, making it one of the mainstream technologies for oil level monitoring.

[0004] Traditional single-frequency ultrasonic oil level gauges typically operate with a fixed frequency and fixed transmission power. Their structure mainly consists of a fixed-frequency ultrasonic transducer, a fixed-gain amplifier circuit, a simple temperature compensation unit, a single signal processing algorithm, and a standard industrial output interface. However, in complex outdoor conditions involving wide temperature ranges, strong electromagnetic fields, and oil mist / foam, this technology exhibits significant drawbacks: First, temperature drift and changes in sound velocity have a significant impact. Large outdoor temperature ranges alter gas medium parameters, causing sound velocity deviations from standard values ​​and directly resulting in measurement errors. Second, it has poor adaptability to complex conditions. Oil mist, foam, and oil surface sloshing within the oil tank can easily generate false echoes, leading to data jumps and misjudgments. Third, the measurement dynamic range is insufficient. Strong echo signals at close range can cause circuit saturation, while weak echo signals at long distances result in insufficient signal-to-noise ratio, failing to maintain measurement accuracy across the entire range. Fourth, it has weak resistance to electromagnetic interference. The strong electromagnetic environment of substations can easily cause signal jitter, data drift, and false alarms. Fifth, its communication interface is limited, supporting only traditional industrial interfaces, making it unsuitable for the multi-protocol access, remote transmission, and cloud management requirements of power IoT and intelligent sensing systems.

[0005] With the rapid development of smart grids and the Internet of Things in the power industry, high precision, high reliability, strong environmental adaptability, and easy integration and expansion are required for transformer online monitoring devices. Existing oil level detection technologies can no longer meet the application needs of next-generation smart substations. Therefore, developing an ultrasonic oil level monitoring device that can overcome temperature drift interference, adapt to complex operating conditions, achieve high-precision measurement across the entire range, and possess strong anti-interference capabilities and multi-interface compatibility has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing oil level detection technologies for oil tanks, such as significant temperature drift, poor adaptability to operating conditions, insufficient dynamic range, weak anti-interference capability, and limited interfaces, this invention provides an ultrasonic oil level monitoring device for oil tanks. This device utilizes three key elements: a high-power ultrasonic probe made of composite materials, multi-frequency scanning adaptive measurement, and power adaptive modulation. It achieves high-precision, high-stability, and strong anti-interference online monitoring of oil levels in oil tanks, while also being compatible with multiple industrial interfaces to meet the integrated application requirements of intelligent sensing systems for the power Internet of Things.

[0007] The present invention employs the following technical solution.

[0008] An ultrasonic oil level monitoring device for an oil storage tank, comprising:

[0009] Composite material high-power ultrasonic sensor, multi-frequency drive and transceiver switching circuit, low-noise receiving front end, MCU main control unit, temperature compensation module, power management module, EMC protection module and multi-standard industrial interface circuit;

[0010] The composite material high-power ultrasonic sensor, multi-frequency drive and transceiver switching circuit, low-noise receiving front-end, temperature compensation module, power management module, EMC protection module and multi-standard industrial interface circuit are all connected to the MCU main control unit.

[0011] The multi-frequency drive and transmit / receive switching circuit, low-noise receiving front-end, temperature compensation module, power management module, multi-standard industrial interface circuit and MCU main control unit are all connected to the EMC protection module.

[0012] Furthermore, the multi-frequency drive and transceiver switching circuit includes a multi-frequency signal generator, a power amplifier, a transceiver switching switch, a variable gain amplifier, and an impedance matching network connected in sequence.

[0013] Furthermore, the low-noise receiver front end includes a low-noise preamplifier (LNA), a controllable gain amplifier, a bandpass filter network, a Schmitt trigger, and a differential input circuit connected in sequence.

[0014] Furthermore, the multi-standard industrial interface circuit includes an RS485 interface unit, a CAN interface unit, an Ethernet interface unit, and a LoRa wireless interface unit.

[0015] Furthermore, the temperature compensation module includes a temperature sensor.

[0016] Furthermore, the probe of the composite high-power ultrasonic sensor uses a high-power ultrasonic transducer made of piezoelectric composite material; the acoustic matching layer of the composite high-power ultrasonic sensor adopts a multi-layer gradient impedance design; and the backing structure of the composite high-power ultrasonic sensor uses a high-damping sound-absorbing material.

[0017] Furthermore, the MCU main control unit acquires the echo time-domain waveform and frequency-domain characteristic parameters transmitted by the high-power ultrasonic sensor of the composite material in real time, calculates the optimal operating frequency through an adaptive algorithm, and automatically switches the frequency to output the optimal operating frequency.

[0018] Furthermore, the formula for the adaptive algorithm is:

[0019] ;

[0020] In this formula, The optimal operating frequency is calculated using an adaptive algorithm; This represents the lower limit of the scanning frequency band for frequency domain characteristic parameters; This represents the upper limit of the scanning frequency band for frequency domain characteristic parameters; The echo signal-to-noise ratio of the echo time-domain waveform; Select an index for the set frequency.

[0021] Furthermore, the MCU main control unit applies a power adaptive modulation method to adjust the transmit power and receive gain in real time based on the measurement distance: when the measurement distance is short, the transmit power is automatically reduced; when the measurement distance is long, the transmit power is automatically increased.

[0022] Furthermore, the formula for the power adaptive modulation method is as follows:

[0023] ;

[0024] In this formula, This represents the adaptive transmit power corresponding to the distance d; The reference transmit power; The power adjustment coefficient is set, typically 0.15; d is the real-time measurement distance.

[0025] The beneficial effects of the present invention are as follows: Compared with the prior art, the technical effects of the present invention include:

[0026] The high-power ultrasonic probe made of composite materials of this invention significantly improves transmission efficiency and receiving sensitivity by optimizing the acoustic matching layer and backing structure, enhancing the echo signal-to-noise ratio, and ensuring clear and stable signals. This hardware-based approach guarantees measurement accuracy and effectively reduces misjudgments caused by noise interference. The multi-frequency scanning adaptive measurement mechanism can identify interference conditions such as oil mist, foam, and oil surface sloshing in real time, automatically switching to the optimal operating frequency to suppress false echoes and data jumps, maintaining stable measurements even in harsh environments and solving the industry problem of poor adaptability of traditional single-frequency technology. The power adaptive modulation technology achieves unsaturated operation at close range and distortion-free operation at long range, controlling measurement errors within a reasonable range across the entire measurement range. Compared to traditional technologies, this improves accuracy and meets the high-precision oil level monitoring requirements of transformer oil conservators. The device adopts a comprehensive EMC protection design, employing multi-level filtering, opto-isolation, and shielding. The device incorporates various measures to adapt to the strong electromagnetic environment of substations, eliminating data jitter and false alarms. With no moving mechanical parts, it experiences no wear or jamming, significantly extending the mean time between failures (MTBF) and meeting the long-term stable operation requirements of power equipment. The temperature compensation module, combining an original sound velocity correction formula with an oil level expansion compensation model, eliminates the effects of temperature drift over a wide temperature range, improving the accuracy of sound velocity calculation and ensuring oil level measurement is unaffected by temperature fluctuations, thus adapting to extreme outdoor environments. Equipped with multi-standard industrial interfaces, it is compatible with traditional power monitoring systems and supports access to the next-generation power IoT platform, enabling remote data transmission, cloud management, and intelligent early warning, reducing system upgrade costs and enhancing intelligence. The non-contact installation method eliminates the need to modify the oil tank structure, facilitating convenient installation and commissioning. With no easily damaged mechanical parts, it requires no daily maintenance, reducing operation and maintenance workload and lowering the total life-cycle cost.

[0027] The ultrasonic oil level monitoring device for oil storage tanks disclosed in this invention completely solves the defects of existing technologies, such as large temperature drift, poor adaptability to operating conditions, insufficient dynamic range, weak anti-interference, and single interface, by using three major elements: high-power ultrasonic probe made of composite material, multi-frequency scanning adaptive measurement, and power adaptive modulation. It achieves high-precision, high-stability, strong anti-interference, and easy-to-integrate online oil level monitoring. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the ultrasonic oil level monitoring device for oil tanks described in this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, any other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0030] like Figure 1 As shown, the ultrasonic oil level monitoring device for an oil tank according to the present invention includes:

[0031] Composite material high-power ultrasonic sensor, multi-frequency drive and transceiver switching circuit, low-noise receiving front end, MCU main control unit, temperature compensation module, power management module, EMC protection module and multi-standard industrial interface circuit;

[0032] The composite material high-power ultrasonic sensor, multi-frequency drive and transceiver switching circuit, low-noise receiving front-end, temperature compensation module, power management module, EMC protection module and multi-standard industrial interface circuit are all connected to the MCU main control unit.

[0033] The multi-frequency drive and transmit / receive switching circuit, low-noise receiving front-end, temperature compensation module, power management module, multi-standard industrial interface circuit and MCU main control unit are all connected to the EMC protection module.

[0034] Specifically, the output of the MCU main control unit is connected to the control terminal of the multi-frequency drive and transceiver switching circuit, the data terminal of the temperature compensation module, the enable terminal of the power management module, and the communication terminal of the multi-standard industrial interface circuit; the input of the MCU main control unit is connected to the digital output terminal of the low-noise receiving front-end and the analog / digital sampling terminal of the temperature compensation module. The input of the multi-frequency drive and transceiver switching circuit comes from the frequency command and power adjustment command of the MCU. The output drive signal of the multi-frequency drive and transceiver switching circuit is sent to the emitter of the composite high-power ultrasonic sensor. The switching control of the multi-frequency drive and transceiver switching circuit is interlocked with the low-noise receiving front-end to achieve transmit-receive timing isolation. The transmitter of the composite high-power ultrasonic sensor is connected to the output of the multi-frequency drive and transceiver switching circuit, and the receiver of the composite high-power ultrasonic sensor is connected to the input of the low-noise receiving front-end. The input of the low-noise receiving front-end comes from the weak echo signal of the sensor, and the output of the low-noise receiving front-end is amplified, filtered, and shaped digital echo signal. The signal is sent to the MCU main control unit; the temperature compensation module collects ambient temperature and oil temperature, and outputs the temperature data to the MCU main control unit for sound velocity correction and oil level compensation; the power management module input is an external wide voltage DC power supply (9–36V), and the power management module output provides power to the MCU main control unit, multi-frequency driver, low-noise front end, temperature module, and interface circuit; the multi-standard industrial interface circuit input is the UART / SPI / CAN / ETH signal of the MCU main control unit, and the multi-standard industrial interface circuit output is to the external standard industrial interface (RS485 / CAN / Ethernet / LoRa).

[0035] Thus, the power management module is powered on, the MCU main control unit is initialized, the multi-frequency drive circuit is configured, ultrasonic waves are emitted, the transmit / receive switching circuit is switched to receive mode, the sensor echo is sent to the low-noise front end, the front end is conditioned and then sent to the MCU main control unit, the MCU main control unit combines the temperature data to calculate until the data is uploaded through the multi-standard interface.

[0036] In addition, the connection structure of the present invention mainly includes: the MCU main control unit is connected to the multi-frequency drive and transceiver switching circuit; the multi-frequency drive and transceiver switching circuit is connected to the composite material high-power ultrasonic sensor; the composite material high-power ultrasonic sensor is connected to the low-noise receiving front end; the low-noise receiving front end is connected to the MCU main control unit; the temperature compensation module is connected to the MCU main control unit; the power management module is connected to all functional modules; and the MCU main control unit is connected to the multi-standard industrial interface circuit.

[0037] In a preferred but non-limiting embodiment of the present invention, the multi-frequency drive and transceiver switching circuit is a dedicated power drive circuit that generates 400kHz–2MHz multi-frequency high-voltage excitation signals and achieves electrical isolation and timing switching for transmission / reception. The multi-frequency drive and transceiver switching circuit includes a multi-frequency signal generator, a power amplifier, a transceiver switching switch, a variable gain amplifier, and an impedance matching network connected in sequence.

[0038] In a preferred but non-limiting embodiment of the present invention, the low-noise receiving front end is a high-precision signal conditioning circuit that performs low-noise amplification, filtering, gain control, and shaping of the weak ultrasonic echo returned by the sensor. The low-noise receiving front end includes a low-noise preamplifier (LNA), a controllable gain amplifier, a bandpass filter network, a Schmitt trigger, and a differential input circuit connected in sequence.

[0039] In a preferred but non-limiting embodiment of the present invention, the multi-standard industrial interface circuit is a multi-protocol output circuit that converts data from the MCU main control unit into industrial standard communication signals, compatible with traditional systems and the power Internet of Things. The multi-standard industrial interface circuit includes an RS485 interface unit, a CAN interface unit, an Ethernet interface unit, and a LoRa wireless interface unit.

[0040] In a preferred but non-limiting embodiment of the present invention, the temperature compensation module includes a temperature sensor.

[0041] In a preferred but non-limiting embodiment of the present invention, the probe of the composite high-power ultrasonic sensor employs a high-power ultrasonic transducer made of piezoelectric composite material, with optimized acoustic matching layer and backing structure design. The acoustic matching layer of the composite high-power ultrasonic sensor adopts a multi-layer gradient impedance design to achieve efficient acoustic-energy coupling between the ultrasonic transducer and the transformer oil medium, improving transmission efficiency. The backing structure of the composite high-power ultrasonic sensor uses high-damping sound-absorbing material to suppress residual vibration interference and improve the clarity of the received signal. The probe of this composite high-power ultrasonic sensor can achieve high-energy transmission and high-sensitivity reception, outputting a high signal-to-noise ratio echo signal, laying a hardware foundation for accurate measurement.

[0042] In a preferred but non-limiting embodiment of the present invention, the MCU main control unit applies a multi-frequency scanning adaptive measurement mechanism to realize multi-frequency combined excitation and cyclic scanning measurement in the 400kHz to 2MHz frequency band. The MCU main control unit acquires the echo time-domain waveform and frequency-domain characteristic parameters transmitted by the high-power ultrasonic sensor of composite material in real time, calculates the optimal operating frequency through an adaptive algorithm, and automatically switches the frequency to output the optimal operating frequency. This adapts to changes in working conditions such as medium parameters, ambient temperature, and oil tank boundary, effectively suppressing interference echoes generated by oil mist, foam, and oil surface sloshing, and eliminating the influence of false signals.

[0043] In a preferred but non-limiting embodiment of the present invention, the formula for the adaptive algorithm is:

[0044] ;

[0045] In this formula, The optimal operating frequency is calculated using an adaptive algorithm; This is the lower limit of the scanning frequency band for the frequency domain characteristic parameters, for example, its value is 400kHz; This is the upper limit of the scanning frequency band for the frequency domain characteristic parameters, for example, its value is 2MHz; The echo signal-to-noise ratio of the echo time-domain waveform; The index is selected for the set frequency, and its value depends on the specific requirements, usually taking the value of 0.85.

[0046] The adaptive algorithm's formula is based on the signal-to-noise ratio (SNR) characteristics to achieve adaptive frequency optimization. The higher the SNR, the closer the optimal frequency is to the high-frequency band, and the stronger the penetration and anti-interference capabilities. The exponential parameter ensures smooth frequency switching without abrupt changes. It solves the shortcomings of traditional single-frequency algorithms that cannot adapt to changes in operating conditions, and achieves optimal signal acquisition under interference environments.

[0047] In a preferred but non-limiting embodiment of the present invention, the MCU main control unit applies a power adaptive modulation method to adjust the transmit power and receive gain in real time based on the measurement distance: when the measurement distance is close, the transmit power is automatically reduced to avoid signal saturation distortion in the front-end circuit; when the measurement distance is far, the transmit power is automatically increased to ensure the echo signal strength and signal-to-noise ratio, thereby achieving stable and high-precision measurement across the entire measurement range.

[0048] In a preferred but non-limiting embodiment of the present invention, the formula for the power adaptive modulation method is:

[0049] ;

[0050] In this formula, This represents the adaptive transmit power corresponding to the distance d; The reference transmit power; The power adjustment coefficient is set, typically 0.15; d is the real-time measurement distance.

[0051] Therefore, the formula of the power adaptive modulation method includes an exponential growth term and a saturation suppression term. At long distances, the exponential term dominates, and the power increases with distance to ensure the echo strength. At short distances, the saturation term dominates, limiting the power output to avoid circuit saturation. This achieves full-range power adaptive matching and solves the problems of near-field saturation and insufficient signal-to-noise ratio in the far field.

[0052] In addition, the temperature compensation module collects ambient temperature and transformer oil temperature in real time, providing real-time temperature data for sound velocity correction and oil level compensation; the power management module realizes wide voltage input, regulated output, and overvoltage and overcurrent protection to ensure stable power supply to the device; the EMC protection module adopts multi-level filtering, opto-isolation, and shielded grounding design to improve the device's resistance to strong electromagnetic interference; the multi-standard industrial interface circuit is compatible with RS485, CAN, Ethernet, LoRa and other communication interfaces, supporting traditional system access and remote data transmission to the power Internet of Things platform.

[0053] Alternative embodiments of the present invention are shown below:

[0054] Ultrasonic probe material alternatives: piezoelectric ceramics, polymer composite materials, and single-crystal piezoelectric materials can be used to replace the composite material described in this invention. All of these can achieve high signal-to-noise ratio signal transmission and reception, with only slight differences in transmission efficiency and sensitivity.

[0055] Operating frequency band adjustment: The multi-frequency scanning frequency band can be adjusted to 300kHz~3MHz, and adaptive scanning can be achieved through different frequency combinations without affecting the core measurement effect;

[0056] Power control alternatives: Power and gain modulation can be achieved using hardware methods such as digital potentiometers, PWM duty cycle adjustment, and variable gain amplifiers, with equivalent functionality.

[0057] Signal processing algorithm alternatives: Time-domain correlation method, frequency-domain FFT analysis, wavelet transform, and machine learning recognition algorithm can be used to replace the echo processing algorithm of this invention, all of which can achieve echo feature extraction and interference suppression.

[0058] The key technical points of this invention are as follows:

[0059] The probe structure of a high-power ultrasonic sensor made of composite materials enables high signal-to-noise ratio ultrasonic signal transmission and reception.

[0060] A multi-frequency scanning adaptive measurement mechanism from 400kHz to 2MHz automatically adapts to changes in environment and medium, enhancing anti-interference capabilities;

[0061] Adaptive modulation technology for transmit power and receive gain ensures high-precision and stable measurement across the entire measurement range;

[0062] Wide-temperature range, high-precision temperature compensation, and multi-standard industrial interface design make it suitable for intelligent integration applications of the power Internet of Things.

[0063] It should be recognized that embodiments of the present invention may be implemented or carried out by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable storage medium.

[0064] The method can be implemented using standard programming techniques, including a non-transitory computer-readable storage medium configured with a computer program in the computer program, wherein the storage medium is configured such that the computer operates in a specific and predefined manner.

[0065] Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system; however, if required, the program can be implemented in assembly or machine language.

[0066] In any case, the language can be either compiled or interpreted.

[0067] Furthermore, for this purpose, the program can run on programmed application-specific integrated circuits.

[0068] The processes described herein (or variations and / or combinations thereof) can be executed under the control of one or more computer systems configured with executable instructions, and can be implemented by hardware or a combination thereof as code (e.g., executable instructions, one or more computer programs, or one or more applications) that commonly executes on one or more processors. The computer program includes a plurality of instructions executable by one or more processors.

[0069] Furthermore, the method can be implemented in any suitable computing platform, including but not limited to personal computers, minicomputers, mainframes, workstations, networked or distributed computing environments, standalone or integrated computer platforms, or in communication with charged particle tools or other imaging devices.

[0070] Various aspects of the present invention can be implemented in machine-readable code stored on a non-transitory storage medium or device, whether portable or integrated into a computing platform, such as a hard disk, optical read and / or write storage medium, RAM, ROM, etc., such that it can be read by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the processes described herein.

[0071] Furthermore, machine-readable code, or parts thereof, can be transmitted via wired or wireless networks.

[0072] When such media includes instructions or programs that combine with a microprocessor or other data processor to implement the steps described above, the invention described herein includes these and other different types of non-transitory computer-readable storage media.

[0073] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An ultrasonic oil level monitoring device for an oil reservoir, characterised in that, include: Composite material high-power ultrasonic sensor, multi-frequency drive and transceiver switching circuit, low-noise receiving front end, MCU main control unit, temperature compensation module, power management module, EMC protection module and multi-standard industrial interface circuit; The composite material high-power ultrasonic sensor, multi-frequency drive and transceiver switching circuit, low-noise receiving front-end, temperature compensation module, power management module, EMC protection module and multi-standard industrial interface circuit are all connected to the MCU main control unit. The multi-frequency drive and transmit / receive switching circuit, low-noise receiving front-end, temperature compensation module, power management module, multi-standard industrial interface circuit and MCU main control unit are all connected to the EMC protection module.

2. The reservoir tank ultrasonic oil level monitoring device of claim 1, wherein, The multi-frequency drive and transceiver switching circuit includes a multi-frequency signal generator, a power amplifier, a transceiver switching switch, a variable gain amplifier, and an impedance matching network connected in sequence.

3. The ultrasonic oil level monitoring device for an oil storage tank according to claim 2, characterized in that, The low-noise receiver front end includes a low-noise preamplifier (LNA), a controllable gain amplifier, a bandpass filter network, a Schmitt trigger, and a differential input circuit, which are connected in sequence.

4. The ultrasonic oil level monitoring device for an oil storage tank according to claim 3, characterized in that, The multi-standard industrial interface circuit includes an RS485 interface unit, a CAN interface unit, an Ethernet interface unit, and a LoRa wireless interface unit.

5. The ultrasonic oil level monitoring device for an oil storage tank according to claim 4, characterized in that, The temperature compensation module includes a temperature sensor.

6. The ultrasonic oil level monitoring device for an oil storage tank according to claim 5, characterized in that, The probe of the high-power ultrasonic sensor made of composite materials is a high-power ultrasonic transducer made of piezoelectric composite material; the acoustic matching layer of the high-power ultrasonic sensor made of composite materials adopts a multi-layer gradient impedance design; and the backing structure of the high-power ultrasonic sensor made of composite materials adopts a high-damping sound-absorbing material.

7. The ultrasonic oil level monitoring device for an oil storage tank according to claim 6, characterized in that, The MCU main control unit acquires the echo time-domain waveform and frequency-domain characteristic parameters transmitted by the high-power ultrasonic sensor of composite materials in real time, calculates the optimal operating frequency through an adaptive algorithm, and automatically switches the frequency to output the optimal operating frequency.

8. The ultrasonic oil level monitoring device for an oil storage tank according to claim 7, characterized in that, The formula for the M-adaptive algorithm is: ； In this formula, The optimal operating frequency is calculated using an adaptive algorithm; This represents the lower limit of the scanning frequency band for frequency domain characteristic parameters; This represents the upper limit of the scanning frequency band for frequency domain characteristic parameters; The echo signal-to-noise ratio of the echo time-domain waveform; Select an index for the set frequency.

9. The ultrasonic oil level monitoring device for an oil storage tank according to claim 8, characterized in that, The MCU main control unit uses a power adaptive modulation method to adjust the transmit power and receive gain in real time based on the measurement distance: when the measurement distance is short, the transmit power is automatically reduced; when the measurement distance is long, the transmit power is automatically increased.

10. The ultrasonic oil level monitoring device for an oil storage tank according to claim 9, characterized in that, The formula for the power adaptive modulation method is: ； In this formula, This represents the adaptive transmit power corresponding to the distance d; The reference transmit power; The power adjustment coefficient is set, typically 0.15; d is the real-time measurement distance.

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