Non-contact monitoring method for transient overvoltage of UHV filter bank circuit breaker

Abstract

The invention discloses a non-contact monitoring method for transient overvoltage of a UHV filter group circuit breaker, relates to the technical field of voltage measurement, and comprises the following steps: pre-processing an acquired overvoltage signal to input the signal as an initial voltage signal into a field programmable logic gate array, the filter decomposition and reconstruction module of the field programmable logic gate array comprises a decomposition module and a reconstruction module, the decomposition module comprises a plurality of decomposition layers connected in sequence, the reconstruction module comprises a plurality of reconstruction layers connected in sequence, the first decomposition layer inputs an initial voltage signal, the last decomposition layer outputs a final decomposition voltage signal, the last reconstruction layer inputs a final decomposition voltage signal, and the first reconstruction layer outputs a final reconstructed voltage signal; based on the filter decomposition and reconstruction module, the initial voltage signal is decomposed and denoised, thereby obtaining a final reconstructed voltage signal, and the non-contact monitoring method realizes online real-time monitoring of circuit breaker overvoltage.

Description

Technical Field

[0001] The invention relates to the technical field of voltage measurement, and in particular to a non-contact monitoring method for transient overvoltage of a UHV filter group circuit breaker. Background Art

[0002] The filter bank circuit breaker is an important device in the UHV converter station. The UHV power grid has a large power adjustment range, the capacitor bank or AC filter bank has a large capacity, and the filter is frequently switched on and off. Switching on and off the filter is a capacitive current switch, which will cause serious overvoltage, damage the insulation of the line equipment, and even cause the one-way reclosing failure, which is very harmful to the system.

[0003] At present, there is no practical online monitoring method for UHV filter group circuit breakers. The traditional electromagnetic voltage transformer commonly used for fault recording has the disadvantages of ferromagnetic saturation, narrow measurement bandwidth, poor transient response capability, and cannot monitor high-frequency transient overvoltage. At the same time, there is no typical waveform definition for fast transient overvoltage in UHV stations. The important feature is that the wave head time is less than 100ns. There is no good means to monitor circuit breaker overvoltage online and no effective data processing method for time-frequency domain processing and analysis of fast transient overvoltage signals. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a non-contact monitoring method for transient overvoltage of a UHV filter group circuit breaker, thereby realizing online real-time monitoring of circuit breaker overvoltage.

[0005] The non-contact monitoring method for transient overvoltage of a UHV filter group circuit breaker proposed in the present invention comprises the following steps:

[0006] Step 1: pre-process the acquired overvoltage signal to input it into a field programmable logic gate array as an initial voltage signal. The filter decomposition and reconstruction module of the field programmable logic gate array includes a decomposition module and a reconstruction module. The decomposition module includes decomposition layer, the reconstruction module includes The output of the current decomposition layer is used as the input of the next decomposition layer. The first decomposition layer inputs the initial voltage signal, and the last decomposition layer outputs the final decomposition voltage signal. The output of the current reconstruction layer is used as the input of the previous reconstruction layer. The last reconstruction layer inputs the final decomposition voltage signal, and the first reconstruction layer outputs the final reconstructed voltage signal.

[0007] Step 2: Wavelet decomposition denoising: multiply the decomposed voltage signal as the input of the current decomposition layer by the pre-stored wavelet filter decomposition coefficient to obtain the decomposed wavelet coefficient, that is, the decomposed voltage signal output by the current layer; use the low-frequency component of the decomposed voltage signal output by the current decomposition layer as the input of the next decomposition layer; perform threshold processing on the high-frequency component of the decomposed voltage signal output by the current decomposition layer and store it;

[0008] Step 3, wavelet reconstruction: The reconstructed low-frequency component as the input of the current reconstruction layer and the high-frequency component stored in the same layer in step 2 are respectively multiplied by the previously stored wavelet reconstruction filter coefficients to obtain a tentatively reconstructed voltage signal, and the tentatively reconstructed voltage signal after the tentative reconstruction is upsampled, and the upsampled tentatively reconstructed voltage signal is used as the output of the current reconstruction layer and stored. Through layer-by-layer reconstruction, the tentatively reconstructed voltage signal output by the first reconstruction layer is used as the final reconstructed voltage signal, wherein the final decomposed voltage signal is input to the last reconstruction layer to perform the first reconstruction. The reconstruction layer is reconstructed, and the reconstructed low-frequency component is used as the first Input to the reconstruction layer.

[0009] Furthermore, in step 1, a broadband transient overvoltage signal is obtained by a non-contact overvoltage sensor based on a bismuth germanate crystal;

[0010] The non-contact overvoltage sensor comprises a crystal probe, a laser source, a polarization-maintaining optical fiber, a circulator and a photodetector;

[0011] The crystal probe is arranged below the first fracture of the circuit breaker, the laser source is connected to the circulator through the polarization-maintaining optical fiber, one end of the circulator is connected to the crystal probe, and the other end is connected to the photoelectric detector.

[0012] Furthermore, the crystal probe is Bi 2 O 3 -GeO 2 A series of compounds, specifically bismuth germanate crystals, when the circuit breaker is over-voltage, the parallel plates induce an induced electromotive force , generating a uniform electric field acting on the crystal probe. The crystal probe produces a birefringence phenomenon based on the Pockels effect, and outputs an overvoltage signal through the photodetector :

[0013] ;

[0014] ;

[0015] ;

[0016] in, is the photodetector conversion voltage coefficient, is the incident light intensity of the crystal probe, is the phase deviation of the crystal probe after birefringence, is the half-wave voltage, is the wavelength of incident light of the crystal probe, is the linear electro-optic coefficient of the crystal probe, is the crystal refractive index of the crystal probe, is the length of the crystal probe in the light transmission direction, Indicates the crystal thickness of the crystal probe perpendicular to the light transmission direction.

[0017] Furthermore, in step one, the acquired overvoltage signal is preprocessed by a signal conditioning circuit, wherein the signal conditioning circuit includes a voltage stabilizing circuit, a differential amplifier circuit, a low-pass filter circuit and a proportional amplifier circuit connected in sequence, the overvoltage signal is input to the voltage stabilizing circuit, and the proportional amplifier circuit outputs the preprocessed overvoltage signal as the initial voltage signal.

[0018] Furthermore, in steps 2 and 3, the Dobesi wavelet is selected as the mother wavelet of the Marat algorithm, and the decomposition and reconstruction formulas of the initial voltage signal are as follows:

[0019] ;

[0020] in, is a discrete serial number; is the initial voltage signal; is the number of decomposition layers or reconstruction layers, , is the initial voltage signal length, is the index of the input initial voltage signal, indicating the sampling points, is the length of the filter, is the wavelet decomposition low-pass filter, is the wavelet decomposition high-pass filter, for In the The wavelet coefficients of the low-frequency part of the decomposition layer, that is, The low-frequency component of the decomposed voltage signal output by the decomposition layer, for In the The wavelet coefficients of the low-frequency part of the decomposition layer are For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer, that is, The high-frequency component of the decomposed voltage signal output by the decomposition layer, For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer.

[0021] Furthermore, the generation formula of the final reconstructed voltage signal is as follows:

[0022] ;

[0023] in, For the The wavelet coefficients of the low-frequency part of the decomposition layer are For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer are Wavelet reconstruction of inverse high-pass filter coefficients, Reconstruct the inverse low-pass filter coefficients for the wavelet.

[0024] Furthermore, the field programmable logic gate array further comprises a phase-locked loop module, an analog-to-digital conversion control module and a ratio calibration module; the phase-locked loop module, the analog-to-digital conversion control module, the filter decomposition and reconstruction module and the ratio calibration module are connected in sequence;

[0025] The phase-locked loop module is used to provide a system clock for the analog-to-digital conversion control module and an overall reset level for the field programmable logic gate array;

[0026] The analog-to-digital conversion control module is used to control the data sampling of the pre-processed overvoltage signal, realize the conversion of the analog signal and the data signal, and store it in the general register as the initial voltage signal;

[0027] The filter decomposition and reconstruction module uses the wavelet decomposition and reconstruction algorithm to perform decomposition and reconstruction processing to obtain the final reconstructed voltage signal;

[0028] The proportional calibration module is used to perform proportional calibration on the amplitude of the final reconstructed voltage signal through a multiplier based on a preset proportional coefficient, and input the calibrated final reconstructed voltage signal into the host computer for real-time display.

[0029] The advantages of the non-contact monitoring method for transient overvoltage of a UHV filter group circuit breaker provided by the present invention are: by setting a non-contact overvoltage sensor based on a BGO crystal, the problem of insufficient accuracy in transient overvoltage monitoring of a circuit breaker with a wide frequency and high amplitude is solved; at the same time, an FPGA is used to implement a wavelet decomposition and reconstruction algorithm, and the advantage of the FPGA hardware parallel data processing speed is brought into play, thereby improving the real-time performance of the time-frequency analysis of the overvoltage signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of the present invention;

[0031] Figure 2 It is a structural schematic diagram of a non-contact monitoring system for transient overvoltage of a circuit breaker;

[0032] Figure 3 It is a structural flow chart of the signal conditioning circuit;

[0033] Figure 4 This is a schematic diagram of the FPGA structure flow. DETAILED DESCRIPTION

[0034] Below, the technical solution of the present invention is described in detail through specific embodiments. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific implementation disclosed below.

[0035] This embodiment provides a non-contact monitoring system for transient overvoltage of a circuit breaker, such as Figure 2 As shown, it includes a non-contact overvoltage sensor based on bismuth germanate (BGO) crystal, a signal conditioning circuit, an FPGA (field programmable gate array) and a host computer which are connected in sequence;

[0036] The overvoltage sensor is arranged below the first break of the circuit breaker to monitor the transient overvoltage of the circuit breaker; the signal conditioning circuit is connected to the non-contact overvoltage sensor to realize the signal conditioning functions of voltage following, low-pass filtering, differential amplification, and proportional adjustable amplification. The FPGA is connected to the signal conditioning circuit, including the PLL (phase-locked loop) module, the ADC (analog-to-digital conversion) control module, the filter decomposition and reconstruction module, and the proportional calibration module; the PLL module realizes the frequency multiplication function, provides the system clock for the onboard ADC control module, and the reset level of the entire system; the ADC control module is used to control the onboard ADC to sample the pre-processed overvoltage signal, realize the conversion of analog signal and data signal, and store it in the general register as the initial voltage signal; the filter decomposition and reconstruction module uses the wavelet decomposition and reconstruction algorithm to decompose and reconstruct the final reconstructed voltage signal; the proportional calibration module uses the pre-set proportional coefficient to perform proportional calibration on the amplitude of the final reconstructed voltage signal through the multiplier, and inputs the calibrated final reconstructed voltage signal into the host computer for real-time display. The host computer is connected to the FPGA to display the final reconstructed voltage signal (monitoring data) after calibration in real time. The process of reconstructing the initial voltage signal by the filter decomposition and reconstruction module of the FPGA is specifically described in steps 2 and 3 below.

[0037] like Figures 1 to 4 As shown, the non-contact monitoring method for transient overvoltage of a UHV filter group circuit breaker proposed by the present invention comprises the following steps:

[0038] Step 1: pre-processing the acquired overvoltage signal to input it into a field programmable logic gate array as an initial voltage signal;

[0039] A broadband transient overvoltage signal is obtained by a non-contact overvoltage sensor based on bismuth germanate crystal. The non-contact overvoltage sensor includes a crystal probe, a 1550nm laser source, a polarization-maintaining fiber, a circulator and a photodetector. The crystal probe is arranged below the first break of the circuit breaker, the laser source is connected to the circulator through a polarization-maintaining fiber, one end of the circulator is connected to the crystal probe, and the other end is connected to the photodetector.

[0040] Overvoltage sensor integrated setting, in the circuit breaker overvoltage When the laser source is generated, it is transmitted to the crystal probe through the polarization-maintaining optical fiber, and the parallel plates induce an induced electromotive force. , induced electromotive force Caused by birefringence of crystal probe:

[0041] ;

[0042] in, is the proportionality coefficient between overvoltage and induced electromotive force.

[0043] Crystal probe is Bi 2 O 3 -GeO 2 Series compounds, specifically Bi 4 Ge 3 O 12 Crystal (bismuth germanate crystal): The crystal probe is based on the Pockels effect. When the circuit breaker is over-voltaged, it produces a birefringence phenomenon and outputs an over-voltage signal through a photodetector. :

[0044] ;

[0045] ;

[0046] ;

[0047] in, is the photodetector conversion voltage coefficient, is the incident light intensity of the crystal probe, is the phase deviation of the crystal probe after birefringence, is the half-wave voltage, is the wavelength of incident light of the crystal probe, is the linear electro-optic coefficient of the crystal probe, is the crystal refractive index of the crystal probe, is the length of the crystal probe in the light transmission direction, Indicates the crystal thickness of the crystal probe perpendicular to the light transmission direction.

[0048] In addition, this embodiment pre-processes the acquired overvoltage signal through a signal conditioning circuit. The signal conditioning circuit includes a voltage stabilizing circuit, a differential amplifier circuit, a low-pass filter circuit, and a proportional amplifier circuit connected in sequence. The overvoltage signal is input to the voltage stabilizing circuit, and the proportional amplifier circuit outputs the pre-processed overvoltage signal as the initial voltage signal. The voltage stabilizing circuit is used to improve the input and output impedance of the circuit to avoid the influence of the load on the weak photoelectric detection signal; the low-pass filter circuit adopts a two-stage Sallen-Key structure to filter out electromagnetic signal interference higher than 50MHz; the differential amplifier circuit adopts a single-ended input and single-ended output form to amplify the differential mode signal to suppress the common mode signal generated by the sensor affected by temperature; the proportional amplifier circuit is set to 1 times, 10 times, and 50 times three gears of amplification, which are controlled by buttons.

[0049] Step 2: Wavelet decomposition and denoising: multiply the decomposed voltage signal as the input of the current decomposition layer by the pre-stored wavelet filter decomposition coefficients to obtain the decomposed wavelet coefficients, that is, the decomposed voltage signal output by the current layer; use the low-frequency component of the decomposed voltage signal output by the current decomposition layer as the input of the next decomposition layer; perform threshold processing on the high-frequency component of the decomposed voltage signal output by the current decomposition layer and store it.

[0050] Step 3, wavelet reconstruction: The reconstructed low-frequency component as the input of the current reconstruction layer and the high-frequency component stored in the same layer in step 2 are respectively multiplied by the previously stored wavelet reconstruction filter coefficients to obtain a tentatively reconstructed voltage signal, and the tentatively reconstructed voltage signal after the tentative reconstruction is upsampled, and the upsampled tentatively reconstructed voltage signal is used as the output of the current reconstruction layer and stored. Through layer-by-layer reconstruction, the tentatively reconstructed voltage signal output by the first reconstruction layer is used as the final reconstructed voltage signal, wherein the final decomposed voltage signal is input to the last reconstruction layer to perform the first reconstruction. The reconstruction layer is reconstructed, and the reconstructed low-frequency component is used as the first Input to the reconstruction layer.

[0051] Field Programmable Gate Array (FPGA) layout: The filter decomposition and reconstruction module of FPGA includes decomposition module and reconstruction module. The decomposition module includes decomposition layer, the reconstruction module includes reconstruction layer, the output of the current decomposition layer is used as the input of the next decomposition layer, the first decomposition layer inputs the initial voltage signal, the last decomposition layer outputs the final decomposition voltage signal, the output of the current reconstruction layer is used as the input of the previous reconstruction layer, the last reconstruction layer inputs the final decomposition voltage signal, and the first reconstruction layer outputs the final reconstructed voltage signal.

[0052] For the initial voltage signal Decomposition and reconstruction: In the decomposition process, the low-frequency component is used as the decomposition transmission decomposition signal, and the high-frequency component output by each decomposition layer is threshold processed and stored as the reconstruction process of the reconstruction module corresponding to the reconstruction layer, for example, as the initial voltage signal , decomposed by decomposition layer, and obtain low-frequency components and high frequency components Therefore, the final decomposition voltage signal output by the last decomposition layer is a low-frequency component and high frequency components , for high frequency components Threshold processing, for the sake of convenience, the high-frequency components processed by threshold in the subsequent reconstruction process are still In order to understand the corresponding relationship between decomposition and reconstruction, and (Here is the high frequency component after threshold processing) as the first The input of the reconstruction layer is used for the Reconstruct the reconstruction layer to obtain the reconstructed , and the reconstructed With the stored right Reconstruction is performed, and after layer-by-layer reconstruction, the output of the first reconstruction layer is the initial voltage signal The final reconstructed voltage signal after reconstruction.

[0053] It can be understood that from the first decomposition layer to the Decomposition layer, and the first reconstruction layer to the The reconstruction layer corresponds to The high-frequency components output by the decomposition layer are stored after threshold processing. The reconstruction layer reconstructs the low-frequency components of the input layer and the The high-frequency components stored in the decomposition layer are used to reconstruct low-frequency components, which will be used as the first The input of the reconstruction layer is The high-frequency components stored in the decomposition layer work together to obtain the first The output of the reconstruction layer is reconstructed layer by layer to obtain the final reconstructed voltage signal, realizing online real-time monitoring of circuit breaker overvoltage. .

[0054] The initial voltage signal is subjected to wavelet decomposition and reconstruction algorithm through the filter decomposition and reconstruction module. The Mallat algorithm is used to achieve fast decomposition and reconstruction. Db4 in the Dobesi wavelet Db is selected as the mother wavelet of the Mallat algorithm. The decomposition and reconstruction formula of the initial voltage signal is as follows:

[0055] ;

[0056] in, is a discrete serial number; is the initial voltage signal; is the number of decomposition layers or reconstruction layers, , is the initial voltage signal length, is the index of the input initial voltage signal, indicating the sampling points, is the length of the filter, is the wavelet decomposition low-pass filter, is the wavelet decomposition high-pass filter, for In the The wavelet coefficients of the low-frequency part of the decomposition layer, that is, The low-frequency component of the decomposed voltage signal output by the decomposition layer, for In the The wavelet coefficients of the low-frequency part (approximate part) of the decomposition layer, that is, The low-frequency component of the decomposed voltage signal output by the decomposition layer, For signal In the The wavelet coefficients of the high-frequency part (detail part) of the decomposition layer, that is, The high-frequency component of the decomposed voltage signal output by the decomposition layer, For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer, that is, The high-frequency component of the decomposed voltage signal output by the decomposition layer.

[0057] The generation formula of the final reconstructed voltage signal obtained by the above decomposition and reconstruction formula is as follows:

[0058] ;

[0059] in, For the The wavelet coefficients of the low-frequency part of the decomposition layer are For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer are Wavelet reconstruction of inverse high-pass filter coefficients, is the wavelet reconstruction inverse low-pass filter coefficient. The final reconstructed voltage signal is calibrated by the proportional calibration module and sent to the host computer for real-time display. The proportional coefficient set in advance in the proportional calibration module is generated as follows: the system voltage data during normal operation of the overvoltage sensor is stored in the ROM (read-only memory) and the ratio with the normal operation voltage output data is calculated to obtain the proportional coefficient; the output amplitude of the final reconstructed voltage signal is corrected based on the proportional coefficient.

[0060] The non-contact overvoltage sensor based on bismuth germanate (BGO) crystal provided in this embodiment has a wide measurement frequency band, a fast response speed, and a high accuracy in measuring broadband transient signals; it realizes non-invasive monitoring of high-voltage power systems and reduces operation and maintenance risks; in addition, it realizes feature extraction and decomposition and reconstruction of transient overvoltages through FPGA hardware, effectively compensating for the poor real-time performance of data processing in the ultra-high voltage transient overvoltage monitoring system, which is of great significance to ensuring the safe and reliable operation of the power grid.

[0061] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A non-contact monitoring method for transient overvoltage of a UHV filter group circuit breaker, characterized in that: The steps include: Step 1: pre-process the acquired overvoltage signal to input it into a field programmable logic gate array as an initial voltage signal. The filter decomposition and reconstruction module of the field programmable logic gate array includes a decomposition module and a reconstruction module. The decomposition module includes decomposition layer, the reconstruction module includes The output of the current decomposition layer is used as the input of the next decomposition layer. The first decomposition layer inputs the initial voltage signal, and the last decomposition layer outputs the final decomposition voltage signal. The output of the current reconstruction layer is used as the input of the previous reconstruction layer. The last reconstruction layer inputs the final decomposition voltage signal, and the first reconstruction layer outputs the final reconstructed voltage signal. Step 2: Wavelet decomposition denoising: multiply the decomposed voltage signal as the input of the current decomposition layer by the pre-stored wavelet filter decomposition coefficient to obtain the decomposed wavelet coefficient, that is, the decomposed voltage signal output by the current layer; use the low-frequency component of the decomposed voltage signal output by the current decomposition layer as the input of the next decomposition layer; perform threshold processing on the high-frequency component of the decomposed voltage signal output by the current decomposition layer and store it; Step 3, wavelet reconstruction: The reconstructed low-frequency component as the input of the current reconstruction layer and the high-frequency component stored in the same layer in step 2 are respectively multiplied by the previously stored wavelet reconstruction filter coefficients to obtain a tentatively reconstructed voltage signal, and the tentatively reconstructed voltage signal after the tentative reconstruction is upsampled, and the upsampled tentatively reconstructed voltage signal is used as the output of the current reconstruction layer and stored. Through layer-by-layer reconstruction, the tentatively reconstructed voltage signal output by the first reconstruction layer is used as the final reconstructed voltage signal, wherein the final decomposed voltage signal is input to the last reconstruction layer to perform the first reconstruction. The reconstruction layer is reconstructed, and the reconstructed low-frequency component is used as the first Input to the reconstruction layer.

2. The non-contact monitoring method for transient overvoltage of a UHV filter bank circuit breaker according to claim 1, characterized in that: In step 1, a broadband transient overvoltage signal is obtained by a non-contact overvoltage sensor based on a bismuth germanate crystal; The non-contact overvoltage sensor comprises a crystal probe, a laser source, a polarization-maintaining optical fiber, a circulator and a photodetector; The crystal probe is arranged below the first fracture of the circuit breaker, the laser source is connected to the circulator through the polarization-maintaining optical fiber, one end of the circulator is connected to the crystal probe, and the other end is connected to the photoelectric detector.

3. The non-contact monitoring method for transient overvoltage of a UHV filter bank circuit breaker according to claim 2, characterized in that: The crystal probe is a Bi2O3-GeO2 compound, specifically a bismuth germanate crystal. When the circuit breaker is over-voltage, the parallel plates induce an induced electromotive force. , generating a uniform electric field acting on the crystal probe. The crystal probe produces a birefringence phenomenon based on the Pockels effect, and outputs an overvoltage signal through the photodetector : ； ； ； in, is the photodetector conversion voltage coefficient, is the incident light intensity of the crystal probe, is the phase deviation of the crystal probe after birefringence, is the half-wave voltage, is the wavelength of incident light of the crystal probe, is the linear electro-optic coefficient of the crystal probe, is the crystal refractive index of the crystal probe, is the length of the crystal probe in the light transmission direction, Indicates the crystal thickness of the crystal probe perpendicular to the light transmission direction.

4. The non-contact monitoring method for transient overvoltage of a UHV filter bank circuit breaker according to claim 2, characterized in that: In step one, the acquired overvoltage signal is preprocessed by a signal conditioning circuit, wherein the signal conditioning circuit includes a voltage stabilizing circuit, a differential amplifier circuit, a low-pass filter circuit, and a proportional amplifier circuit connected in sequence. The overvoltage signal is input to the voltage stabilizing circuit, and the proportional amplifier circuit outputs the preprocessed overvoltage signal as the initial voltage signal.

5. The non-contact monitoring method for transient overvoltage of a UHV filter bank circuit breaker according to claim 1, characterized in that: In steps 2 and 3, the Dobesi wavelet is selected as the mother wavelet of the Marat algorithm, and the decomposition and reconstruction formulas of the initial voltage signal are as follows: ； in, is a discrete serial number; is the initial voltage signal; is the number of decomposition layers or reconstruction layers, , is the initial voltage signal length, is the index of the input initial voltage signal, indicating the sampling points, is the length of the filter, is the wavelet decomposition low-pass filter, is the wavelet decomposition high-pass filter, for In the The wavelet coefficients of the low-frequency part of the decomposition layer, that is, The low-frequency component of the decomposed voltage signal output by the decomposition layer, for In the The wavelet coefficients of the low-frequency part of the decomposition layer are For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer, that is, The high-frequency component of the decomposed voltage signal output by the decomposition layer, For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer.

6. The non-contact monitoring method for transient overvoltage of a UHV filter bank circuit breaker according to claim 5, characterized in that: The generation formula of the final reconstructed voltage signal is as follows: ； in, For the The wavelet coefficients of the low-frequency part of the decomposition layer are For signal In the The wavelet coefficients of the high-frequency part of the decomposition layer are Wavelet reconstruction of inverse high-pass filter coefficients, Reconstruct the inverse low-pass filter coefficients for the wavelet.

7. The non-contact monitoring method for transient overvoltage of a UHV filter bank circuit breaker according to claim 1, characterized in that: The field programmable logic gate array further includes a phase-locked loop module, an analog-to-digital conversion control module and a ratio calibration module; the phase-locked loop module, the analog-to-digital conversion control module, the filter decomposition and reconstruction module and the ratio calibration module are connected in sequence; The phase-locked loop module is used to provide a system clock for the analog-to-digital conversion control module and an overall reset level for the field programmable logic gate array; The analog-to-digital conversion control module is used to control the data sampling of the pre-processed overvoltage signal, realize the conversion of the analog signal and the data signal, and store it in the general register as the initial voltage signal; The filter decomposition and reconstruction module uses the wavelet decomposition and reconstruction algorithm to perform decomposition and reconstruction processing to obtain the final reconstructed voltage signal; The proportional calibration module is used to perform proportional calibration on the amplitude of the final reconstructed voltage signal through a multiplier based on a preset proportional coefficient, and input the calibrated final reconstructed voltage signal into the host computer for real-time display.

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