Substation fiber optic cabinet cooling fan fault monitoring device and monitoring method

Abstract

This invention provides a fault monitoring device and method for cooling fans in substation fiber optic cabinets. The fault monitoring device includes: a sound pickup sensor module for collecting audio signals from the fan; a temperature sensor module for collecting temperature signals from the inside and outside of the substation fiber optic cabinet; and a microprocessor module connected to both the sound pickup sensor module and the temperature sensor module for analyzing and processing the audio and temperature signals, and determining whether the fan has malfunctioned based on the analysis results. It utilizes the sound pickup module to obtain the vibration or friction spectrum of the fan operation, combined with the temperature difference between the inside and outside of the substation fiber optic cabinet for auxiliary judgment, to accurately monitor whether the fan has malfunctioned. Furthermore, this method does not require the implantation of any monitoring devices inside the existing equipment, completely replacing manual inspection, offering good real-time performance, timely fault detection, and prevention of accidents from escalating, which is of great significance for ensuring the safe operation of equipment.

Description

Technical Field

[0001] This invention relates to the field of fault detection technology, and in particular to a fault monitoring device and method for the cooling fan of a substation fiber optic cabinet. Background Technology

[0002] To ensure the continuous and stable operation of internal equipment 24 hours a day, fiber optic cabinets in substations typically rely on fans for heat dissipation. Especially in the hot summer, the fans need to run continuously throughout the day to reduce the temperature inside the cabinet. If the fan fails during the high-temperature period, the temperature inside the cabinet will rise rapidly, which can easily lead to abnormalities in communication equipment and seriously affect the normal operation of the substation. Summary of the Invention

[0003] To overcome the above shortcomings, the present invention provides a fault monitoring device and method for cooling fans in substation fiber optic cabinets. It uses a microphone module to obtain the vibration or friction spectrum of the fan during operation, and combines it with the temperature difference between the inside and outside of the substation fiber optic cabinet for auxiliary judgment, so as to accurately monitor whether the fan has failed.

[0004] The technical solution provided by this invention is as follows:

[0005] On one hand, the present invention provides a fault monitoring device for cooling fans in substation fiber optic cabinets, wherein the substation fiber optic cabinet is equipped with a fan for heat dissipation, and the fault monitoring device includes:

[0006] The audio sensor module is installed inside the fiber optic cabinet of the substation near the fan to collect the audio signal from the fan.

[0007] Temperature sensor modules are configured both inside and outside the fiber optic cabinet in the substation to collect temperature signals from inside and outside the fiber optic cabinet.

[0008] The microprocessor module is connected to the audio sensor module and the temperature sensor module respectively, and is used to analyze and process the audio signal and temperature signal, and determine whether the fan is malfunctioning based on the analysis results.

[0009] On the other hand, the present invention provides a method for monitoring the failure of a cooling fan in a substation fiber optic cabinet, wherein the substation fiber optic cabinet is equipped with a fan for heat dissipation, and the failure monitoring method includes:

[0010] The audio signal of the fan is collected by a sound pickup sensor module; the sound pickup sensor module is installed inside the fiber optic cabinet of the substation near the fan;

[0011] Temperature signals inside and outside the fiber optic cabinet of the substation are collected by temperature sensor modules; the temperature sensor modules are respectively configured inside and outside the fiber optic cabinet of the substation.

[0012] The microprocessor module analyzes and processes the audio and temperature signals, and determines whether the fan is malfunctioning based on the analysis results.

[0013] This invention provides a substation fiber optic cabinet cooling fan fault monitoring device and method, which accurately identifies fan faults and ensures equipment safety. By comprehensively analyzing the abnormal characteristics of the fan acoustic spectrum and the fluctuation data of the temperature difference between the inside and outside of the cabinet, this temperature-acoustic hybrid method effectively avoids the limitations of a single monitoring method. Compared with conventional methods relying on human hearing, it significantly improves the accuracy of fan fault diagnosis, providing a more reliable guarantee for the stable operation of substation fiber optic cabinets. Furthermore, this method does not require the implantation of any monitoring devices inside the existing equipment, completely replacing manual inspections. It offers good real-time performance, enabling timely fault detection and preventing the escalation of accidents, which is of great significance for ensuring the safe operation of equipment. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of an embodiment of the substation fiber optic cabinet cooling fan fault monitoring device of the present invention;

[0015] Figure 2 This is a circuit diagram of a multivibrator in an example of the present invention;

[0016] Figure 3 For the purposes of this invention Figure 2 The example shown is a curve illustrating the relationship between the output frequency of the multivibrator circuit and temperature.

[0017] Figure 4 This is a flowchart illustrating an embodiment of the substation fiber optic cabinet cooling fan fault monitoring method of the present invention.

[0018] Figure label:

[0019] 100 - Fault monitoring device, 110 - Sound pickup sensor module, 120 - Temperature sensor module, 130 - Microprocessor module. Detailed Implementation

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0021] One embodiment of the present invention provides a fault monitoring device for the cooling fan of a substation fiber optic cabinet, such as... Figure 1 As shown, the fault monitoring device 100 includes:

[0022] The audio sensor module 110 is installed inside the fiber optic cabinet of the substation near the fan to collect the audio signal of the fan.

[0023] Temperature sensor module 120 is configured inside and outside the fiber optic cabinet of the substation, respectively, to collect temperature signals inside and outside the fiber optic cabinet of the substation.

[0024] The microprocessor module 130 is connected to the audio sensor module 110 and the temperature sensor module 120 respectively, and is used to analyze and process the audio signal and temperature signal, and determine whether the fan is malfunctioning based on the analysis results.

[0025] The substation fiber optic cabinet is equipped with a fan for heat dissipation. In order to improve the accuracy of fan failure monitoring, this embodiment uses a comprehensive judgment based on the temperature and sound mixing method.

[0026] The function of the audio sensor module 110 is to collect audio signals during the operation of the fan. Therefore, it is installed inside the communication cabinet near the fan and can be implemented using an electret microphone (MIC). The appropriate type can be selected based on the application requirements. The number of audio sensor modules 110 can also be configured in multiple ways according to application needs.

[0027] To further improve accuracy, an audio amplifier circuit is also included, with its input terminal connected to the output terminal of the microphone module 110 and its output terminal connected to the I / O port of the microprocessor module 130. This amplifier amplifies the audio signal acquired by the microphone module 110. The selection of the audio amplifier circuit can be based on the specific requirements. In one example, the audio amplifier circuit uses an LM386 low-voltage audio power amplifier, with an operating voltage of 4V-12V and an output power of 0.25W-1W.

[0028] Temperature sensor modules 120 are configured inside and outside the fiber optic cabinet of the substation, that is, temperature sensor modules 120 are configured inside and outside the cabinet to detect the temperature inside and outside the cabinet at the same time, so that the subsequent microprocessor module 130 can use the temperature difference between the inside and outside of the cabinet to help determine the fan failure.

[0029] Theoretically, any sensor capable of temperature detection can be used for the selection of temperature sensor module 120. However, due to the harsh electromagnetic environment inside and outside the cabinet, this embodiment proposes to use a thermistor in conjunction with a multivibrator circuit to convert temperature changes into frequency changes and achieve detection through optocoupler isolation, thereby greatly improving the anti-interference capability of the temperature measurement circuit. Specifically, temperature sensor module 120 includes: a thermistor, a multivibrator circuit, a switching circuit, and an optocoupler circuit. The thermistor is connected to the input terminal of the multivibrator circuit, the input terminal of the switching circuit is connected to the output terminal of the multivibrator circuit, the optocoupler circuit is connected to the output terminal of the switching circuit, and the output terminal of the optocoupler circuit is connected to the input terminal of microprocessor module 130. The oscillation frequency of the multivibrator circuit changes with the resistance value of the thermistor. When the multivibrator circuit outputs a high level, the switching circuit is turned on, and then the optocoupler circuit is turned on. Microprocessor module 130 obtains the oscillation frequency of the multivibrator circuit by acquiring the number of times the optocoupler switches through interrupt technology, thereby obtaining the temperature measurement value.

[0030] In one example, the multivibrator circuit uses the NE555N chip, the NTC thermistor is an NTC10k thermistor with a constant of 3950 ohms as the temperature sensing element, and the optocoupler circuit uses an optocoupler chip of model P521-1. For example... Figure 2 As shown, one end of the thermistor R1 is connected to the TRIG and THR terminals of the NE555N chip, and the other end is connected to the DISC terminal of the NE555N chip. The multivibrator circuit also includes: a 10Ω resistor R2, one end of which is connected to the DISC terminal of the NE555N chip, and the other end is connected to the RST terminal and VCC terminal of the NE555N chip; and a capacitor C1, one end of which is connected to the TRIG and THR terminals of the NE555N chip, and the other end is connected to the CVOLT terminal and GND terminal of the NE555N chip. The switching circuit is an NPN transistor. Q 1. Its base is connected to the output terminal OUT of the NE555N chip via resistor R3, its collector is connected to the input terminal of the optocoupler chip P521-1, and its emitter is grounded. The output terminal of the optocoupler chip P521-1 is connected to the I / O port of the microprocessor module via resistor R6.

[0031] When the temperature of the thermistor R1 changes, its resistance changes, and the OUT frequency f of the NE555N chip also changes. The change pattern is as follows: When the NE555N chip's output terminal OUT is high, the transistor... When the NE555N chip output OUT is low, the optocoupler chip P521-1 is turned on. Thus, the optocoupler chip P521-1 switches once for each oscillation of the NE555N chip. The microprocessor can obtain the oscillation frequency by obtaining the number of optocoupler switches through interrupt technology, thereby obtaining the temperature measurement value.

[0032] The microprocessor module combines high-efficiency computing with precise control capabilities. It can perform complex logical judgments and data processing through programming, and also respond to external events in real time using built-in timers, interrupt controllers, and other components, meeting the real-time requirements of industrial control, intelligent devices, and other scenarios. Its highly integrated design encapsulates the microprocessor core, memory, various interfaces, and control units into a single, fully functional microcomputing unit. Internally, it includes a processor core responsible for instruction execution and data processing (such as ARM Cortex or RISC-V architectures), integrated storage modules such as Flash and RAM, and rich peripheral interfaces such as GPIO, UART, I2C, and SPI, enabling direct data interaction with external devices. In this embodiment, the specific model of the microprocessor module can be selected based on actual conditions; for example, an STM32 microprocessor chip can be used, as long as the invention's purpose is achieved. In this model, the ADC resolution is 12-bit (STM32 default), and the quantization accuracy affects the dynamic range.

[0033] To obtain the temperature measurement value, the microprocessor module 130 includes: an oscillation frequency acquisition unit, used to acquire the number of optocoupler switching cycles through interrupt technology, and then obtain the oscillation frequency of the multivibrator circuit; a frequency range determination unit, connected to the oscillation frequency acquisition unit, used to determine the frequency range in which the acquired oscillation frequency falls, the frequency range being divided by an oscillation frequency / temperature relationship curve obtained by fitting a temperature / resistance lookup table based on a thermistor and a multivibrator circuit frequency calculation formula, within each divided frequency range, the oscillation frequency and temperature have a linear relationship; and a temperature calculation unit, connected to the frequency range determination unit, used to calculate the corresponding temperature measurement value based on the frequency range determined by the frequency range determination unit.

[0034] Before monitoring, based on the known thermistor temperature-resistance value comparison table and the oscillation circuit frequency calculation formula, the corresponding frequencies for different resistance values ​​are calculated, thus obtaining the frequencies at different temperatures. The relationship between the output frequency and temperature is then plotted using Matlab with a polynomial fitting method. Figure 3 As shown, the horizontal axis represents frequency in Hz (Hertz); the vertical axis represents temperature in °C (degrees Celsius).

[0035] As shown in the figure, the oscillation frequency exhibits a non-linear relationship with temperature. Although curve fitting and neural networks can effectively improve the accuracy of temperature calculations, the microprocessor module 130 has limited accuracy in floating-point calculations, making it difficult to handle high-order fitting equations and neural network calculations. Therefore, in this embodiment, the frequency-temperature curve is pre-divided into several frequency intervals based on the curve's derivative. A linear equation between frequency and temperature is established within each frequency interval, thus obtaining a piecewise frequency-temperature function. Based on this, after obtaining the oscillation frequency of the multivibrator circuit by acquiring the number of optocoupler switches using interrupt technology, the microprocessor module 130 finds the corresponding frequency interval and calculates the corresponding temperature measurement value based on the linear relationship within that interval. Figure 2 In the example shown, the temperature and resistance value of the NTC10k thermistor are shown in Table 1.

[0036] Table 1: Correspondence between resistance value and temperature

[0037]

[0038] To obtain the fan's spectral information, the microprocessor module 130 further includes: an ADC sampling unit, used to further sample the fan audio signal acquired by the audio sensor module 110 to obtain a digital audio signal; a frequency domain signal conversion unit, connected to the ADC sampling unit, used to perform a discrete Fourier transform on the digital audio signal generated by the ADC sampling unit to obtain a frequency domain audio signal; an amplitude extraction unit, connected to the frequency domain signal conversion unit, used to extract the amplitude of each frequency component in the frequency domain audio signal generated by the frequency domain signal conversion unit; and a frequency feature analysis unit, connected to the amplitude extraction unit, used to analyze the frequency characteristics of the fan's vibration or friction based on the amplitude information extracted by the amplitude extraction unit.

[0039] The digital audio signal sampled by the ADC sampling unit is as follows:

[0040]

[0041] Where Ts represents the sampling interval, determined by the clock of the ADC sampling unit, e.g., Ts = 1 / fs; fs is the sampling frequency, which must satisfy the Nyquist sampling theorem: fs ≥ 2fmax. Since the frequency of fan noise is usually <10kHz, fs ≥ 20kHz is preferred. The number of sampling points N determines the FFT frequency resolution, e.g., N = 1024.

[0042] The frequency domain signal conversion unit converts the time domain signal x The Discrete Fourier Transform (DFT) formula for converting [n] to the frequency domain signal X[k] is as follows:

[0043]

[0044] To determine whether a fan is malfunctioning based on temperature measurements and audio signals, the microprocessor module 130 further includes: a fan spectrum judgment unit, used to determine whether the frequency of fan vibration or friction exceeds a preset frequency threshold; a temperature difference judgment unit, used to determine whether the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than a preset temperature threshold; and a fault determination unit, which, together with the fan spectrum judgment unit and the temperature difference judgment unit, is used to further determine whether the fan is malfunctioning based on the results of the fan spectrum judgment unit and the fault determination unit; when the frequency of fan vibration or friction exceeds the preset frequency threshold, and the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than the preset temperature threshold, the fan is determined to be malfunctioning.

[0045] The preset frequency threshold is determined based on the fan used in the actual scenario, such as being limited to 1kHz-2kHz; the preset temperature difference threshold can also be set in combination with factors such as weather, such as being set to 2℃-8℃.

[0046] The judgment process specifically includes:

[0047] When the fan sound vibration spectrum is detected to exceed the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is not greater than the preset temperature threshold, it is determined that the fan has not malfunctioned.

[0048] When the fan sound vibration spectrum is detected to exceed the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is greater than the preset temperature threshold, it is determined that the fan may be malfunctioning.

[0049] When the fan's sound vibration spectrum is detected to be within the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is not greater than the preset temperature threshold, it is determined that the fan has not malfunctioned.

[0050] When the fan's sound vibration spectrum is detected to be within the preset frequency threshold, check the temperature difference between the inside and outside of the cabinet. If the temperature difference is greater than the preset temperature threshold, it is determined that the fan is not malfunctioning and may be caused by excessively high ambient temperature.

[0051] For clock synchronization, this embodiment also includes a clock module connected to the microprocessor's output I / O port. In one example, a DS1302 clock chip is selected, with a normal operating voltage range of 2.5-5.5V. The main power supply VCC2 is powered by a 3.3V system power supply, and a 3.3V coin cell battery is used as a backup power supply VCC1. This module can still operate normally when the main power supply to the circuit board is interrupted. The DS1302 communicates with the microprocessor module 130 via I2C, using a 32.768kHz external crystal oscillator.

[0052] In another embodiment, the fault monitoring device 100 is also equipped with a display module connected to the output I / O port of the microprocessor module 130 to display monitoring data in real time. The display module can be a TFT LCD screen, etc., as long as it can achieve the display purpose, and no specific limitation is made here. In one example, a domestic 4.3-inch enhanced HMI programmable touch screen TJC4827K043_011X is selected as the display module to realize human-computer interaction. This touch screen can be directly designed on the PC using host computer development software. It can add buttons, checkboxes, curve waveforms, fonts, background images, and create simple animations. This type of touch screen generally requires voltage power supply and is also voltage compatible. The touch screen communicates with the processor through a UART serial port, and the communication protocol only includes string instructions and terminators, which can effectively reduce development time.

[0053] In another embodiment, to enable communication between the microprocessor module 130 and external devices, the fault monitoring device 100 is also equipped with a communication module connected to a communication interface corresponding to the output of the microprocessor module 130. In one example, the communication module uses an RS485 communication module, which is widely used in industrial control, instruments, meters, mechatronics products, and many other fields. It typically transmits over twisted-pair cables, with a standard node count of 32, a maximum communication distance of 1200m, a receiver differential input range of -7V to +12V, and a receiver input sensitivity of ±200MV. RS485 uses a differential transmission method with A and B wires for data transmission. The output logic level is determined by calculating the voltage difference between the A and B wires. The voltages at the differential input terminals are denoted as VA and VB, respectively. When the difference between VA and VB is greater than or equal to 0.2V, the output logic level is 1; when the difference between VA and VB is less than 0.2V, the output logic level is 0. RS485 uses twisted-pair transmission with a maximum transmission rate of 10Mbps and an impedance characteristic of 120Ω. Therefore, a 120Ω matching resistor is added to the output terminal of the design to ensure system transmission stability and eliminate reflected signals. The online fault monitoring device 100 for the mechanical characteristics of high-voltage circuit breakers typically operates in environments with complex strong electromagnetic fields and generally uses transient suppression diodes to protect the circuit.

[0054] In another embodiment, a storage module connected to the output I / O port of the microprocessor module 130 is also configured for data storage. For example, a W25Q128 flash memory is selected as the storage module. It has an internal capacity of 16MB, divided into 256 blocks, each block further divided into 16 sectors, for a total of 4096 sectors. Each sector contains 4KB of data, with an erase / write cycle of up to 100,000 times and a data retention period of 20 years, meeting practical usage requirements. The W25Q128 connects to the microprocessor module via an SPI interface.

[0055] To power each module, a power supply module is also configured in this embodiment. In the selection examples of the electronic components mentioned above, the power supply module uses a 9V rechargeable lithium battery as the power supply for the circuit. It is small in size and can be recharged and reused repeatedly, saving resources. According to the selected scheme, ±5V power is required to power the filter and voltage follower, 5V for the storage module, and 3.3V for the remaining modules. Therefore, in the design process, while fully considering the magnitude of the power supply voltage and the power supply ripple, it is also necessary to consider factors such as the output current, conversion efficiency, and heat dissipation of the power supply chip. Low-voltage linear power regulator chips LM2940-5 and LM1117-3.3 can be selected. The LM2940-5 chip steps down and stabilizes the 9V power supply to 5V, and then the LM1117-3.3 chip regulates it to 3.3V. The 5V negative power supply uses the voltage flip chip MX660, which directly outputs -5V from a positive 5V input, with simple peripheral circuitry and small output error.

[0056] In the above embodiments, the vibration spectrum of the fan is obtained by the sound pickup sensor module. Based on the vibration spectrum generated by the fan rotation, the fan is monitored to see if it is working properly, completely replacing the human ear recognition method. At the same time, in order to more accurately determine whether the fan has malfunctioned, the temperature difference method is introduced to assist in determining whether the fan has malfunctioned, further improving the judgment accuracy.

[0057] Another embodiment of the present invention provides a method for monitoring the failure of a cooling fan in a substation fiber optic cabinet, such as... Figure 4 As shown, the fault monitoring methods include:

[0058] S10 collects the audio signal from the fan through a sound pickup sensor module; the sound pickup sensor module is installed inside the fiber optic cabinet of the substation near the fan;

[0059] S20 collects temperature signals from the inside and outside of the substation fiber optic cabinet through temperature sensor modules; temperature sensor modules are configured inside and outside the substation fiber optic cabinet respectively;

[0060] The S30 uses a microprocessor module to analyze and process audio and temperature signals, and determines whether the fan is malfunctioning based on the analysis results.

[0061] The substation fiber optic cabinet is equipped with a fan for heat dissipation. In order to improve the accuracy of fan failure monitoring, this embodiment uses a comprehensive judgment based on the temperature and sound mixing method.

[0062] The function of the audio sensor module is to collect audio signals during the fan's operation. Therefore, it is installed inside the communication cabinet near the fan and can be implemented using electret microphones (MICs), with the selection made according to the application requirements. The number of audio sensor modules can also be configured in multiple ways based on application needs.

[0063] To further improve accuracy, an audio amplifier circuit is also included, with its input connected to the output of the microphone module and its output connected to the I / O port of the microprocessor module. This amplifies the audio signal acquired by the microphone module. The selection of the audio amplifier circuit can be based on the specific requirements. In one example, the audio amplifier circuit uses the LM386 low-voltage audio power amplifier, which operates at 4V-12V and has an output power of 0.25W-1W.

[0064] Temperature sensor modules are configured both inside and outside the substation fiber optic cabinet, meaning that temperature sensor modules are installed both inside and outside the cabinet to detect the temperature inside and outside the cabinet at the same time. This allows the subsequent microprocessor module to use the temperature difference between the inside and outside of the cabinet to help determine fan failures.

[0065] Theoretically, any sensor capable of temperature detection can be used for the selection of the temperature sensor module. However, due to the harsh electromagnetic environment inside and outside the cabinet, this embodiment proposes using a thermistor in conjunction with a multivibrator circuit to convert temperature changes into frequency changes and achieve detection through optocoupler isolation, thereby significantly improving the anti-interference capability of the temperature measurement circuit. Specifically, the temperature sensor module includes: a thermistor, a multivibrator circuit, a switching circuit, and an optocoupler circuit. The thermistor is connected to the input terminal of the multivibrator circuit, the input terminal of the switching circuit is connected to the output terminal of the multivibrator circuit, the optocoupler circuit is connected to the output terminal of the switching circuit, and the output terminal of the optocoupler circuit is connected to the input terminal of the microprocessor module. The oscillation frequency of the multivibrator circuit varies with the resistance value of the thermistor. When the multivibrator circuit outputs a high level, the switching circuit conducts, which in turn conducts the optocoupler circuit. The microprocessor module obtains the oscillation frequency of the multivibrator circuit by acquiring the number of times the optocoupler switches through interrupt technology, thus obtaining the temperature measurement value.

[0066] To obtain the temperature measurement value, the microprocessor module uses interrupt technology to obtain the number of optocoupler switching cycles, thereby obtaining the oscillation frequency of the multivibrator circuit and thus the temperature measurement value. This process includes: obtaining the number of optocoupler switching cycles through interrupt technology to obtain the oscillation frequency of the multivibrator circuit; determining the frequency range of the obtained oscillation frequency, which is divided by the oscillation frequency / temperature relationship curve obtained by fitting a temperature / resistance comparison table based on the thermistor and the frequency calculation formula of the multivibrator circuit. Within each frequency range, the oscillation frequency and temperature have a linear relationship; and calculating the corresponding temperature measurement value based on the determined frequency range.

[0067] Before monitoring, based on the known thermistor temperature-resistance value comparison table and the oscillation circuit frequency calculation formula, the corresponding frequencies for different resistance values ​​are calculated, thus obtaining the frequencies at different temperatures. The relationship between the output frequency and temperature is then plotted using Matlab with a polynomial fitting method. Figure 3 As shown, the horizontal axis represents frequency in Hz (Hertz); the vertical axis represents temperature in °C (degrees Celsius).

[0068] As shown in the figure, the oscillation frequency exhibits a non-linear relationship with temperature. Although curve fitting and neural networks can effectively improve the accuracy of temperature calculations, the microprocessor module has limited accuracy in floating-point calculations, making it difficult to handle high-order fitting equations and neural network calculations. Therefore, in this embodiment, the frequency-temperature curve is pre-divided into several frequency intervals based on the curve's derivative. A linear equation between frequency and temperature is established within each frequency interval, thus obtaining a piecewise frequency-temperature function. Based on this, the microprocessor module obtains the oscillation frequency of the multivibrator circuit by acquiring the number of optocoupler switches using interrupt technology, finds the corresponding frequency interval, and then calculates the corresponding temperature measurement value based on the linear relationship within that frequency interval.

[0069] To obtain the fan's spectral information, the microprocessor module analyzes and processes the audio and temperature signals, and determines whether the fan is malfunctioning based on the analysis results. This process also includes:

[0070] S31 further samples the fan audio signal collected by the sound pickup sensor module to obtain a digital audio signal.

[0071] The sampled digital audio signal is as follows:

[0072]

[0073] Where Ts represents the sampling interval, determined by the ADC clock, e.g., Ts = 1 / fs; fs is the sampling frequency, which must satisfy the Nyquist sampling theorem: fs ≥ 2fmax. Since the frequency of fan noise is usually <10kHz, fs ≥ 20kHz is preferred. The number of sampling points N determines the FFT frequency resolution, e.g., N = 1024.

[0074] S32 performs a discrete Fourier transform on the digital audio signal to obtain a frequency domain audio signal.

[0075] Time domain signal x The Discrete Fourier Transform (DFT) formula for converting [n] to the frequency domain signal X[k] is as follows:

[0076]

[0077] S33 extracts the amplitude of each frequency component in the frequency domain audio signal;

[0078] S34 analyzes the frequency characteristics of fan vibration or friction based on the extracted amplitude information.

[0079] To determine whether a fan is malfunctioning based on temperature measurements and audio signals, a microprocessor module analyzes and processes the audio and temperature signals. The analysis results are then used to determine if the fan is malfunctioning. This process also includes:

[0080] S35 determines whether the frequency of fan vibration or friction exceeds a preset frequency threshold;

[0081] S36 Determines whether the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than a preset temperature threshold.

[0082] S37 further determines whether the fan has malfunctioned based on the frequency judgment result and the temperature difference judgment result;

[0083] S38 When the frequency of fan vibration or friction exceeds the preset frequency threshold, and the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than the preset temperature threshold, the fan is judged to have malfunctioned.

[0084] The preset frequency threshold is determined based on the fan used in the actual scenario, such as being limited to 1kHz-2kHz; the preset temperature difference threshold can also be set in combination with factors such as weather, such as being set to 2℃-8℃.

[0085] The judgment process specifically includes:

[0086] When the fan sound vibration spectrum is detected to exceed the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is not greater than the preset temperature threshold, it is determined that the fan has not malfunctioned.

[0087] When the fan sound vibration spectrum is detected to exceed the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is greater than the preset temperature threshold, it is determined that the fan may be malfunctioning.

[0088] When the fan's sound vibration spectrum is detected to be within the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is not greater than the preset temperature threshold, it is determined that the fan has not malfunctioned.

[0089] When the fan's sound vibration spectrum is detected to be within the preset frequency threshold, check the temperature difference between the inside and outside of the cabinet. If the temperature difference is greater than the preset temperature threshold, it is determined that the fan is not malfunctioning and may be caused by excessively high ambient temperature.

[0090] It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fault monitoring device for cooling fans in fiber optic cabinets of substations, characterized in that, The substation fiber optic cabinet is equipped with a fan for heat dissipation, and the fault monitoring device includes: The audio sensor module is installed inside the fiber optic cabinet of the substation near the fan to collect the audio signal from the fan. Temperature sensor modules are configured both inside and outside the fiber optic cabinet in the substation to collect temperature signals from inside and outside the fiber optic cabinet. The microprocessor module is connected to the audio sensor module and the temperature sensor module respectively, and is used to analyze and process the audio signal and temperature signal, and determine whether the fan is malfunctioning based on the analysis results; The microprocessor module also includes: The fan spectrum determination unit is used to determine whether the frequency of fan vibration or friction exceeds a preset frequency threshold. The temperature difference judgment unit is used to determine whether the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than a preset temperature threshold. The fault determination unit, together with the fan spectrum determination unit and the temperature difference determination unit, is used to further determine whether the fan has malfunctioned based on the results of the fan spectrum determination unit and the fault determination unit; when the frequency of fan vibration or friction exceeds a preset frequency threshold, and the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than a preset temperature threshold, the fan is determined to have malfunctioned. When the fan sound vibration spectrum is detected to exceed the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is not greater than the preset temperature threshold, it is determined that the fan has not malfunctioned. When the fan sound vibration spectrum is detected to be no more than the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is no greater than the preset temperature threshold, it is determined that the fan has not malfunctioned. When the fan's sound vibration spectrum is detected to be within the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is greater than the preset temperature threshold, it is determined that the fan has not malfunctioned.

2. The fault monitoring device as described in claim 1, characterized in that, The temperature sensor module includes: The thermistor, multivibrator circuit, switching circuit, and optocoupler circuit are included. The thermistor is connected to the input terminal of the multivibrator circuit, the input terminal of the switching circuit is connected to the output terminal of the multivibrator circuit, the optocoupler circuit is connected to the output terminal of the switching circuit, and the output terminal of the optocoupler circuit is connected to the input terminal of the microprocessor module. The oscillation frequency of the multivibrator circuit changes with the resistance of the thermistor; when the multivibrator circuit outputs a high level, the switching circuit is turned on, and then the optocoupler circuit is turned on; the microprocessor module obtains the number of times the optocoupler switches through interrupt technology to obtain the oscillation frequency of the multivibrator circuit, thereby obtaining the temperature measurement value.

3. The fault monitoring device as described in claim 2, characterized in that, The microprocessor module includes: The oscillation frequency acquisition unit is used to obtain the number of optocoupler switching cycles through interrupt technology, and then obtain the oscillation frequency of the multivibrator circuit. The frequency range determination unit is connected to the oscillation frequency acquisition unit and is used to determine the frequency range in which the oscillation frequency is located based on the acquired oscillation frequency. The frequency range is divided by the oscillation frequency / temperature relationship curve obtained by fitting the temperature / resistance comparison table of the thermistor and the frequency calculation formula of the multivibrator circuit. Within each divided frequency range, the oscillation frequency and temperature have a linear relationship. A temperature calculation unit, connected to the frequency range determination unit, is used to calculate the corresponding temperature measurement value based on the frequency range determined by the frequency range determination unit.

4. The fault monitoring device as described in any one of claims 1-3, characterized in that, The microprocessor module also includes: The ADC sampling unit is used to further sample the fan audio signal collected by the audio sensor module to obtain a digital audio signal; A frequency domain signal conversion unit, connected to the ADC sampling unit, is used to perform a discrete Fourier transform on the digital audio signal generated by the ADC sampling unit to obtain a frequency domain audio signal. An amplitude extraction unit, connected to the frequency domain signal conversion unit, is used to extract the amplitude of each frequency component in the frequency domain audio signal generated by the frequency domain signal conversion unit. The frequency feature analysis unit, connected to the amplitude extraction unit, is used to analyze the frequency characteristics of the fan's vibration or friction based on the amplitude information extracted by the amplitude extraction unit.

5. A method for monitoring the fault of a cooling fan in a substation fiber optic cabinet, characterized in that, The substation fiber optic cabinet is equipped with a fan for heat dissipation, and the fault monitoring method includes: The audio signal of the fan is collected by a sound pickup sensor module; the sound pickup sensor module is installed inside the fiber optic cabinet of the substation near the fan; Temperature signals inside and outside the fiber optic cabinet of the substation are collected by temperature sensor modules; the temperature sensor modules are respectively configured inside and outside the fiber optic cabinet of the substation. The microprocessor module analyzes and processes the audio and temperature signals, and determines whether the fan is malfunctioning based on the analysis results. The step of analyzing and processing the audio and temperature signals using a microprocessor module, and determining whether the fan is malfunctioning based on the analysis results, also includes: Determine whether the frequency of fan vibration or friction exceeds a preset frequency threshold; Determine whether the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than a preset temperature threshold; Based on the frequency and temperature difference results, further determine whether the fan has malfunctioned; When the frequency of fan vibration or friction exceeds the preset frequency threshold, and the temperature difference between the inside and outside of the substation fiber optic cabinet is greater than the preset temperature threshold, the fan is judged to be faulty. When the fan sound vibration spectrum is detected to exceed the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is not greater than the preset temperature threshold, it is determined that the fan has not malfunctioned. When the fan sound vibration spectrum is detected to be no more than the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is no greater than the preset temperature threshold, it is determined that the fan has not malfunctioned. When the fan's sound vibration spectrum is detected to be within the preset frequency threshold, the temperature difference between the inside and outside of the cabinet is checked. If the temperature difference is greater than the preset temperature threshold, it is determined that the fan has not malfunctioned.

6. The fault monitoring method as described in claim 5, characterized in that, The temperature sensor module includes: The thermistor, multivibrator circuit, switching circuit, and optocoupler circuit are included. The thermistor is connected to the input terminal of the multivibrator circuit, the input terminal of the switching circuit is connected to the output terminal of the multivibrator circuit, the optocoupler circuit is connected to the output terminal of the switching circuit, and the output terminal of the optocoupler circuit is connected to the input terminal of the microprocessor module. When the multivibrator circuit outputs a high level, the switching circuit is turned on, which in turn turns on the optocoupler circuit; when the resistance of the thermistor changes, the oscillation frequency of the multivibrator circuit changes accordingly. The step of analyzing and processing the audio and temperature signals using a microprocessor module, and determining whether the fan is malfunctioning based on the analysis results, includes: The microprocessor module obtains the oscillation frequency of the multivibrator circuit by acquiring the number of optocoupler switching cycles through interrupt technology, thereby obtaining the temperature measurement value.

7. The fault monitoring method as described in claim 6, characterized in that, The microprocessor module obtains the number of optocoupler switches using interrupt technology to get the oscillation frequency of the multivibrator circuit, thereby obtaining the temperature measurement value, including: The number of times the optocoupler switches is switched is obtained through interrupt technology, and then the oscillation frequency of the multivibrator circuit is obtained. The frequency range in which the oscillation frequency is located is determined based on the obtained oscillation frequency. The frequency range is divided by the oscillation frequency / temperature relationship curve obtained by fitting the temperature / resistance comparison table of the thermistor and the frequency calculation formula of the multivibrator circuit. Within each divided frequency range, the oscillation frequency and temperature have a linear relationship. Based on the determined frequency range, the corresponding temperature measurement value is calculated.

8. The fault monitoring method according to any one of claims 5-7, characterized in that, The step of analyzing and processing the audio and temperature signals using a microprocessor module, and determining whether the fan is malfunctioning based on the analysis results, also includes: The fan audio signal collected by the sound pickup sensor module is further sampled to obtain a digital audio signal; The frequency domain audio signal is obtained by performing a discrete Fourier transform on the digital audio signal. The amplitude of each frequency component in the frequency domain audio signal is extracted; The extracted amplitude information is used to analyze the frequency characteristics of fan vibration or friction.

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