High-voltage box three-phase temperature on-line monitoring and early warning system and control method thereof

Abstract

A high-voltage box three-phase temperature on-line monitoring and early warning system disclosed by the present invention comprises a temperature measurement optical fiber, a photoelectric conversion module and a data processing module, the temperature measurement optical fiber comprises an optical fiber sleeve, one end of the optical fiber sleeve is connected with a temperature measurement head, the other end of the optical fiber sleeve is connected with the photoelectric conversion module, the temperature measurement head comprises a housing, the housing is provided with a positioning hole, and the positioning hole is connected with the photoelectric conversion module. An outer heat-conducting fin is arranged on the bottom surface of the shell, an inner heat-conducting fin is arranged in the shell, one end of the inner heat-conducting fin is fixedly connected with the outer heat-conducting fin, a fluorescent material layer is filled between the outer heat-conducting fin and the inner heat-conducting fin, one end of the signal output optical fiber is embedded in the fluorescent material layer, and the other end of the signal output optical fiber is connected with the temperature measurement signal input end of the photoelectric conversion module. An opening is formed in the inner heat-conducting piece, one end of the laser input optical fiber is fixed to the opening and irradiates laser to the fluorescent material layer, and the other end of the laser input optical fiber is connected with the laser output end of the photoelectric conversion module. According to the invention, the defects in the prior art can be improved, and the use convenience of the fluorescence thermodetector is improved.

Description

Technical Field

[0001] This invention relates to the field of power safety monitoring technology, and in particular to an online monitoring and early warning system for the three-phase temperature of a high-voltage box and its control method. Background Technology

[0002] As wind farms continue to expand and wind turbine operating voltage levels gradually increase, high-voltage enclosures have become crucial equipment in the power collection and transmission process. These enclosures contain key components such as three-phase cable joints, surge arresters, and switchgear, with cable joints being the most vulnerable and prone to failure. If cable joints have poor connections, excessive contact resistance, or reduced insulation due to moisture, they are highly susceptible to localized overheating during operation. If not detected and addressed promptly, this can lead to joint burnout, cable bursts, or even large-scale power outages, posing a serious threat to the safe and stable operation of the wind farm. Currently, most wind farms rely on maintenance personnel to periodically inspect cable joints using infrared thermometers or thermal imagers. While this method is manual and suitable for outage repairs or routine maintenance, it cannot provide real-time monitoring of temperature changes during operation, potentially missing the development of potential hazards.

[0003] A fluorescence fiber optic thermometer is a thermometer that utilizes the temperature characteristics of fluorescent materials. Specifically, when a fluorescent material is excited by light of a specific wavelength, it emits fluorescence, and the lifetime or intensity of this fluorescence changes with temperature. When the fluorescent material is irradiated by an excitation light source, electrons transition to a higher energy level. After the excitation light is removed, the electrons return to the ground state, releasing fluorescence. The resulting fluorescence signal is then transmitted along an optical fiber channel, eventually reaching a photodetector. The photodetector, acting as a photoelectric conversion module, converts the received fluorescence signal into an electrical signal. Finally, a signal processing unit processes the electrical signal, analyzes the fluorescence lifetime decay curve, extracts the fluorescence lifetime parameter, and calculates the corresponding temperature value, thereby achieving accurate temperature measurement of the object being measured.

[0004] Existing fluorescent fiber optic thermometers have strict requirements for the installation location of the temperature measuring head, making them very inconvenient to use in wind farms. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a three-phase temperature online monitoring and early warning system and control method for high-voltage boxes, which can overcome the shortcomings of the prior art and improve the ease of use of fluorescent thermometers.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows.

[0007] A three-phase temperature online monitoring and early warning system for a high-voltage box includes a temperature-sensing optical fiber, a photoelectric conversion module, and a data processing module. The temperature-sensing optical fiber includes an optical fiber sheath, with one end connected to a temperature sensor and the other end connected to the photoelectric conversion module. The temperature sensor includes a housing with positioning holes. An outer heat-conducting sheet is located on the bottom surface of the housing, and an inner heat-conducting sheet is located inside the housing. One end of the inner heat-conducting sheet is fixedly connected to the outer heat-conducting sheet, and a fluorescent material layer is filled between the outer and inner heat-conducting sheets. One end of a signal output optical fiber is embedded in the fluorescent material layer, and the other end is connected to the temperature signal input terminal of the photoelectric conversion module. An opening is provided on the inner heat-conducting sheet, and one end of a laser input optical fiber is fixed to the opening, directing light towards the fluorescent material. The material layer is irradiated with laser light, and the other end of the laser input fiber is connected to the laser output end of the photoelectric conversion module. The temperature measuring head is connected to the fiber optic sleeve through a flexible connector. A flexible partition is set inside the flexible connector. The signal output fiber and the laser input fiber are located on both sides of the flexible partition. Rigid support rods are fixed at both ends of the flexible partition. Elastic sleeves are fixed at the top of the rigid support rods. The signal output fiber and the laser input fiber are respectively passed through the corresponding elastic sleeves. The length of the signal output fiber and the laser input fiber between the two elastic sleeves is greater than the length of the flexible partition. A flexible support rod is set at the midpoint of the flexible partition. A rigid sleeve is fixed at the top of the flexible support rod. The signal output fiber and the laser input fiber are respectively passed through the corresponding rigid sleeves.

[0008] Preferably, waterproof sealing rings are provided on the outer sides of both ends of the flexible connector.

[0009] Preferably, an elastic reinforcing sheet is provided on the inner side of the waterproof sealing ring, one end of which is pressed against the waterproof sealing ring, and the other end of which is fixed to the side wall of the flexible connector.

[0010] A control method for the above-mentioned online monitoring and early warning system for three-phase temperature of a high-voltage box includes the following steps: the photoelectric conversion module uses a blue LED to generate excitation pulse light, which is irradiated by a laser input optical fiber to a fluorescent material layer. After the fluorescent material layer is excited, it generates a fluorescent signal. The fluorescent signal is input into the photoelectric conversion module through a signal output optical fiber and converted into an electrical signal. The data processing module processes the electrical signal, calculates the temperature at the temperature measuring head, and issues an alarm when the temperature exceeds the alarm threshold.

[0011] Preferably, a dynamic adaptive threshold is used for the alarm threshold. The generation of the dynamic adaptive threshold includes the following steps: Configure the LSTM module with the loss function as follows: ,in, The actual measured temperature. It is the quantile prediction output by the model. These are quantile weighting coefficients, using historical data sequences. The training set is composed of these elements and input into the LSTM module for training. Let L represent the sequence of all times from time t-L+1 to time t. It is a three-phase current. H represents ambient temperature, H represents ambient humidity, and Time represents time encoding. Input the current data sequence into the LSTM module to obtain the current alarm threshold.

[0012] Preferably, the LSTM module has two serial forget gates. The output of the first forget gate and the forgotten data are input into the second forget gate. The first forget gate calculates the forget operation vector based on the new input data and the current cell state through an activation function, and performs forgetting processing. The second forget gate calculates the forget operation vector based on the input data and the current cell state through an activation function. Then, the gradient vector of the forgotten content of the two forget operations is calculated, and the activation function of the second forget gate is adjusted so that the nonlinearity of the gradient vector of the forgotten content of the two forget operations is greater than a set threshold.

[0013] The beneficial effects of adopting the above technical solution are as follows: This invention improves the structure of the temperature measuring head and protects the optical fiber, allowing for adjustments to the angle and bending degree during installation according to the installation environment, thus facilitating installation and use in high-voltage boxes. Furthermore, by designing an adaptive alarm threshold generation algorithm, it learns the normal temperature distribution of the cable under different environments and operating conditions, reducing the occurrence of false alarms. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a high-voltage box three-phase temperature online monitoring and early warning system in a specific embodiment of the present invention.

[0015] Figure 2 This is a structural diagram of a temperature measuring head in a specific embodiment of the present invention.

[0016] Figure 3 This is a structural diagram of a flexible connector in a specific embodiment of the present invention.

[0017] Figure 4 This is a structural diagram of a waterproof sealing ring in a specific embodiment of the present invention.

[0018] Figure 5 This is a structural diagram of a light source driving unit in a specific embodiment of the present invention.

[0019] Figure 6 This is a structural diagram of a photoelectric detection unit in a specific embodiment of the present invention.

[0020] Figure 7 This is a structural diagram of the signal conditioning unit and the analog-to-digital conversion unit in a specific embodiment of the present invention. Detailed Implementation

[0021] Reference Figure 1-4 The high-voltage box three-phase temperature online monitoring and early warning system disclosed in this invention includes a temperature-sensing optical fiber, a photoelectric conversion module 2, and a data processing module 1. The temperature-sensing optical fiber includes an optical fiber sleeve 3, one end of which is connected to a temperature-sensing head 4, and the other end of which is connected to the photoelectric conversion module 2. The temperature-sensing head 2 includes a shell 6, with a positioning hole 7 on the shell 6. An outer heat-conducting sheet 8 is provided on the bottom surface of the shell 6, and an inner heat-conducting sheet 9 is provided inside the shell 6. One end of the inner heat-conducting sheet 9 is fixedly connected to the outer heat-conducting sheet 8, and a fluorescent material layer 10 is filled between the outer heat-conducting sheet 8 and the inner heat-conducting sheet 9. One end of a signal output optical fiber 11 is embedded in the fluorescent material layer 10, and the other end of the signal output optical fiber 11 is connected to the temperature-sensing signal input end of the photoelectric conversion module 2. An opening 12 is provided on the inner heat-conducting sheet 9, and one end of a laser input optical fiber 13 is fixed to the opening 12 to irradiate the fluorescent material layer 10. The laser input fiber 13 is connected to the laser output end of the photoelectric conversion module 2 at the other end. The temperature measuring head 4 is connected to the fiber optic sleeve 3 through a flexible connector 5. A flexible partition 14 is provided inside the flexible connector 5. The signal output fiber 11 and the laser input fiber 13 are located on both sides of the flexible partition 14. Rigid support rods 15 are fixed at both ends of the flexible partition 14. An elastic sleeve 16 is fixed at the top of the rigid support rod 15. The signal output fiber 11 and the laser input fiber 13 are respectively inserted into the corresponding elastic sleeves 16. The length of the signal output fiber 11 and the laser input fiber 13 between the two elastic sleeves 16 is greater than the length of the flexible partition 14. A flexible support rod 17 is provided at the midpoint of the flexible partition 14. A rigid sleeve 18 is fixed at the top of the flexible support rod 17. The signal output fiber 11 and the laser input fiber 13 are respectively inserted into the corresponding rigid sleeves 18.

[0022] The control method of the above-mentioned high-voltage box three-phase temperature online monitoring and early warning system includes the following steps: the photoelectric conversion module 2 uses a blue LED to generate excitation pulse light, which is irradiated by the laser input fiber 13 to the fluorescent material layer 10. After the fluorescent material layer 10 is excited, it generates a fluorescent signal. The fluorescent signal is input into the photoelectric conversion module 2 through the signal output fiber 11 and converted into an electrical signal. The data processing module 1 processes the electrical signal, calculates the temperature at the temperature measuring head 4, and issues an alarm when the temperature exceeds the alarm threshold.

[0023] This invention fills the fluorescent material layer 10 between two inner and outer heat-conducting sheets, which allows the fluorescent material layer 10 to be heated uniformly. Simultaneously, it reduces the impact of elastic deformation on the heating uniformity of the fluorescent material layer 10 when the temperature sensor 4 undergoes elastic deformation. The flexible connector 5 has redundant fiber optic cable arrangement. When the flexible connector 5 bends, the flexible partition 14 undergoes synchronous elastic deformation. The tops of the rigid support rods 15 on one side of the bending direction move closer together, shortening the fiber length between the two elastic sleeves 16. Simultaneously, the flexible support rod 17 moves in the opposite direction of the bending direction along with the flexible partition 14, and vice versa on the other side, allowing the fiber optic cable within the flexible connector 5 to adapt to the bending state of the flexible connector 5.

[0024] Waterproof sealing rings 19 are respectively provided on the outer sides of both ends of the flexible connector 5, and elastic reinforcing sheets 20 are provided on the inner side of the waterproof sealing rings 19. One end of the elastic reinforcing sheet 20 is pressed against the waterproof sealing ring 19, and the other end of the elastic reinforcing sheet 20 is fixed inside the side wall of the flexible connector 5. The waterproof sealing ring structure designed in this invention can adapt to frequent bending actions and solve the problem of decreased sealing effect after repeated bending of traditional sealing rings.

[0025] Data processing module 1 can be implemented using a remote industrial control computer or MCU. Photoelectric conversion module 2 includes a light source driving unit to control the LED / laser diode (LD) to generate excitation pulse light, ensuring the stability and repeatability of the excitation fluorescence signal; a photodetector unit that uses a photodiode (PD) to convert the returned fluorescence signal into a weak current signal; a signal conditioning unit that performs voltage conversion, amplification, and filtering on the current signal obtained from photodetector to obtain an analog voltage signal with appropriate amplitude; and an analog-to-digital converter (ADC) unit that converts the conditioned analog signal into a digital signal and maintains strict synchronization with the system clock to ensure the time resolution of fluorescence lifetime measurement.

[0026] The light source driving unit is the starting point of the entire photoelectric conversion module. Its main task is to provide a stable and controllable pulsed driving current for the excitation light source (high-brightness LED), thereby ensuring the stability of the excitation light intensity. This unit must be able to generate a narrow pulse current with a steep rise time and maintain a constant current amplitude to avoid fluorescence lifetime measurement errors caused by driving fluctuations. Its circuit consists of a pulse generator, a constant current driving circuit, a power amplifier, and a protection circuit.

[0027] like Figure 5As shown, the workflow of the light source driving unit is as follows: First, the microcontroller outputs a narrow-pulse-width PWM control signal through the GPIO pin. This signal is then sent to the MOSFET gate driver (U2) via a waveform shaping circuit to ensure that the power MOSFET (Q1) can switch quickly. The power MOSFET, blue LED (LED1), and current sampling resistor (Rsense) are connected in series between the power supply and ground to form the main loop. To achieve constant current drive, the circuit is designed with closed-loop negative feedback control: when current flows through Rsense, a voltage drop (Vsense) is generated. This voltage is input to the operational amplifier (U1) and compared with a precision reference voltage source (Vref). The operational amplifier adjusts the output voltage according to the comparison result, and controls the conduction level of the MOSFET through the driver, thereby stabilizing the operating current of the LED. When the current is too large, Vsense increases, the output of U1 decreases, the MOSFET conduction weakens, and the current drops; conversely, the opposite is also true.

[0028] The photodetector unit is the sensing front end of the photoelectric conversion module. Its function is to convert the weak fluorescence signal returned from the optical fiber into a measurable voltage signal. Because the fluorescence intensity and its attenuation characteristics vary with temperature, these signals are often extremely weak, thus placing high demands on the sensitivity, noise control, and signal integrity of the detector unit. This unit mainly consists of a photodiode (PD), a bias circuit, and a transimpedance amplifier (TIA).

[0029] like Figure 6 As shown, the photodetector unit is responsible for converting the weak fluorescence signal into a voltage signal. Its connection relationship and signal processing flow are as follows: the fluorescence signal from the optocoupler of the data acquisition module is introduced into the photosensitive surface of the photodiode (PD1) via the fiber optic interface. To reduce junction capacitance and improve response speed, PD1 is reverse-biased by a bias voltage (Vbias) and operates in photoconductive mode. The anode of PD1 is connected to the non-inverting input (ground) of the operational amplifier (U3), while the cathode is connected to the inverting input of U3. U3 is a JFET input type operational amplifier with a picoampere (pA) input bias current to reduce measurement error. When fluorescence illuminates PD1, a photocurrent proportional to the light intensity is generated. Due to the virtual ground characteristic of the operational amplifier, the inverting input of U3 remains at a potential close to 0 V, so almost all of the photocurrent flows through the feedback resistor. To ensure circuit stability, a feedback capacitor is connected in parallel with the feedback resistor. This is because the junction capacitance of the photodiode itself forms a pole with the feedback resistor, which can easily lead to high-frequency oscillations. Introducing a feedback capacitor creates a zero in the feedback network, effectively compensating for phase lag and ensuring stable circuit operation. Ultimately, the unit outputs an analog voltage signal with a shape consistent with the fluorescence decay curve, providing input for subsequent signal conditioning and analog-to-digital conversion.

[0030] The signal conditioning unit primarily amplifies, filters, and shapes the weak voltage signal output from the photodetector unit. This unit consists of a low-noise amplifier, a low-pass filter, and a signal shaping circuit. The low-noise amplifier first linearly amplifies the input signal, increasing the millivolt level signal to the volt level while maintaining a high signal-to-noise ratio. Subsequently, the low-pass filter suppresses high-frequency switching noise and low-frequency drift noise, preserving the effective bandwidth of the fluorescence signal and ensuring the integrity of the attenuation curve characteristics.

[0031] The analog-to-digital conversion unit is the last component of the photoelectric conversion module 2. Its main function is to digitize the analog voltage signal and provide computable data for the data processing module 1.

[0032] like Figure 7 As shown, the voltage signal from the transimpedance amplifier first enters the signal conditioning unit. This unit employs a second-order active low-pass filter structure based on an operational amplifier (U4). Its main functions are twofold: first, to provide additional voltage gain, amplifying the millivolt-level input signal to the volt level, thereby matching the input dynamic range of the ADC; and second, to effectively filter out high-frequency noise (such as switching power supply noise) and low-frequency drift that exceed the signal bandwidth, ensuring that the waveform characteristics of the fluorescence decay curve are not disrupted. The conditioned analog voltage signal has a moderate amplitude and controlled noise, allowing it to be directly sampled by the analog-to-digital converter (ADC). The ADC is the final stage of the photoelectric conversion module, and its core component is a successive approximation ADC (U5) with a 12-bit resolution and a sampling rate of no less than 2 kSPS. High resolution ensures the precision of temperature calculation, while a sufficient sampling rate guarantees the complete capture of the fluorescence decay curve. Under the control of a microcontroller (MCU, U6), the ADC performs high-speed sampling and quantization of the conditioned analog voltage, outputting a series of digital values. The ADC communicates with the MCU via a high-speed SPI bus. The MCU, acting as the master, initiates sampling and reads data using the chip select signal (CS) and clock signal (SCLK). At this point, the optical signal representing the fluorescence decay curve has completed the conversion from analog voltage to digital signal, becoming a digital data stream that data processing module 1 can directly process, providing a reliable data foundation for subsequent temperature calculation and dynamic early warning algorithms.

[0033] Of course, there is more than one way to implement the photoelectric conversion module 2, and it can also be implemented using other methods of existing technology, which will not be described in detail here.

[0034] Traditional wind power cable temperature monitoring typically employs a fixed threshold strategy, which has significant limitations: firstly, cable temperature is affected by multiple factors such as ambient temperature, humidity, and load current fluctuations, making false alarms easily generated using only a fixed threshold; secondly, true faults often manifest as a sharp temperature increase before tripping, and a fixed threshold cannot provide early warning. This invention uses a dynamic adaptive threshold for alarms. The generation of the dynamic adaptive threshold includes the following steps… Configure the LSTM module with the loss function as follows: ,in, The actual measured temperature. It is the quantile prediction output by the model. These are quantile weighting coefficients, using historical data sequences. The training set is composed of these elements and input into the LSTM module for training. Let L represent the sequence of all times from time t-L+1 to time t. It is a three-phase current. H represents ambient temperature, H represents ambient humidity, and Time represents time encoding. Input the current data sequence into the LSTM module to obtain the current alarm threshold.

[0035] To improve the sensitivity of the LSTM module to multidimensional data and avoid the problems of gradient vanishing and excessive data output fluctuations, this invention sets up two sequential forgetting gates in the LSTM module. The output of the first forgetting gate and the forgotten data are input into the second forgetting gate. The first forgetting gate calculates the forgetting operation vector based on the new input data and the current cell state through an activation function, and performs forgetting processing. The second forgetting gate calculates the forgetting operation vector based on the input data and the current cell state through an activation function, and then calculates the gradient vector of the forgotten content between the two forgetting operations. The activation function of the second forgetting gate is adjusted so that the nonlinearity of the gradient vector of the forgotten content between the two forgetting operations is greater than a set threshold.

[0036] This invention improves the structure of the fluorescence thermometer, making it more suitable for use inside high-voltage boxes in wind farms. Simultaneously, by generating adaptively adjustable alarm thresholds using an LSTM module, alarm accuracy can be improved.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A three-phase temperature online monitoring and early warning system for a high-voltage box, comprising a temperature-measuring optical fiber, a photoelectric conversion module (2), and a data processing module (1), characterized in that: The temperature-measuring optical fiber includes an optical fiber sleeve (3), one end of which is connected to a temperature measuring head (4), and the other end of which is connected to a photoelectric conversion module (2). The temperature measuring head (2) includes a housing (6), a positioning hole (7) on the housing (6), an outer heat-conducting plate (8) on the bottom surface of the housing (6), and an inner heat-conducting plate (9) inside the housing (6). One end of the inner heat-conducting plate (9) is fixedly connected to the outer heat-conducting plate (8), and the outer heat-conducting plate (8) and the inner heat-conducting plate (9) are connected to each other. A fluorescent material layer (10) is filled between the heat exchange sheets (9). One end of the signal output fiber (11) is embedded in the fluorescent material layer (10), and the other end of the signal output fiber (11) is connected to the temperature measurement signal input terminal of the photoelectric conversion module (2). An opening (12) is provided on the inner heat-conducting sheet (9). One end of the laser input fiber (13) is fixed on the opening (12) to irradiate the fluorescent material layer (10) with laser light. The other end of the laser input fiber (13) is connected to the photoelectric conversion module. (2) The laser output end is connected; the temperature measuring head (4) is connected to the fiber optic sleeve (3) through the flexible connector (5). A flexible partition (14) is provided inside the flexible connector (5). The signal output fiber (11) and the laser input fiber (13) are located on both sides of the flexible partition (14). Rigid support rods (15) are fixed at both ends of the flexible partition (14). An elastic sleeve (16) is fixed at the top of the rigid support rod (15). The signal output fiber (11) and the laser input fiber (13) are respectively inserted into the corresponding elastic sleeve (16). The length of the signal output fiber (11) and the laser input fiber (13) between the two elastic sleeves (16) is greater than the length of the flexible partition (14). A flexible support rod (17) is provided at the midpoint of the flexible partition (14). A rigid sleeve (18) is fixed at the top of the flexible support rod (17). The signal output fiber (11) and the laser input fiber (13) are respectively inserted into the corresponding rigid sleeve (18).

2. The online monitoring and early warning system for three-phase temperature of high-voltage box according to claim 1, characterized in that: Waterproof sealing rings (19) are provided on the outer sides of both ends of the flexible connector (5).

3. The online monitoring and early warning system for three-phase temperature of high-voltage box according to claim 2, characterized in that: An elastic reinforcing sheet (20) is provided on the inner side of the waterproof sealing ring (19). One end of the elastic reinforcing sheet (20) is pressed against the waterproof sealing ring (19), and the other end of the elastic reinforcing sheet (20) is fixed inside the side wall of the flexible connector (5).

4. A control method for the online monitoring and early warning system for three-phase temperature of a high-voltage box as described in any one of claims 1-3, characterized in that... Includes the following steps: The photoelectric conversion module (2) uses a blue LED to generate an excitation pulse light, which is then irradiated by a laser input fiber (13) onto the fluorescent material layer (10). The fluorescent material layer (10) generates a fluorescent signal after being excited. The fluorescent signal is then input into the photoelectric conversion module (2) through a signal output fiber (11) and converted into an electrical signal. The data processing module (1) processes the electrical signal and calculates the temperature at the temperature measuring head (4). When the temperature exceeds the alarm threshold, an alarm is issued.

5. The control method of the high-voltage box three-phase temperature online monitoring and early warning system according to claim 4, characterized in that: The alarm threshold adopts a dynamic adaptive threshold, and the generation of the dynamic adaptive threshold includes the following steps: Configure the LSTM module with the loss function as follows: ,in, The actual measured temperature. It is the quantile prediction output by the model. These are quantile weighting coefficients, using historical data sequences. The training set is composed of these elements and input into the LSTM module for training. Let L represent the sequence of all times from time t-L+1 to time t. It is a three-phase current. H represents ambient temperature, H represents ambient humidity, and Time represents time encoding. Input the current data sequence into the LSTM module to obtain the current alarm threshold.

6. The control method of the high-voltage box three-phase temperature online monitoring and early warning system according to claim 5, characterized in that: The LSTM module has two sequential forget gates. The output of the first forget gate and the forgotten data are input into the second forget gate. The first forget gate calculates the forget operation vector based on the new input data and the current cell state through an activation function, and performs forgetting processing. The second forget gate calculates the forget operation vector based on the input data and the current cell state through an activation function. Then, the gradient vector of the forgotten content of the two forget operations is calculated. The activation function of the second forget gate is adjusted so that the non-linearity of the gradient vector of the forgotten content of the two forget operations is greater than a set threshold.

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