GIS ultrahigh frequency online monitoring device and method based on signal multiplexing

Abstract

The invention provides a GIS ultrahigh frequency online monitoring device and method based on signal multiplexing, and relates to the technical field of power grids. The online monitoring device is designed, the ultrahigh-frequency sensors are arranged on the inner walls of the GIS air chambers, the non-contact directional couplers are arranged on the outer walls of the GIS air chambers, ultrahigh-frequency signal transmission is achieved through coupling of the non-contact directional couplers and the ultrahigh-frequency sensors, and partial discharge detection can be achieved without perforating the GIS air chambers. The local detection box is arranged on the ground of the area where each GIS air chamber is located, and the multi-channel intelligent switching matrix in the local detection box is connected with the non-contact directional coupler of each GIS air chamber, so that polling switching detection of partial discharge in each GIS air chamber is realized, and operation and maintenance personnel do not need to climb to work; the problem of low GIS partial discharge detection efficiency caused by single-channel serial operation, high-altitude operation dependence and the like in the GIS partial discharge detection technology is solved, and the detection efficiency of GIS partial discharge detection is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power grid, and particularly relates to a GIS ultra-high frequency online monitoring device and method based on signal multiplexing. BACKGROUND

[0002] As a core facility of power system, the partial discharge (PD) detection of gas insulated switchgear (GIS) is crucial to the safety of power grid. Although the current ultra-high frequency (UHF) online monitoring system can collect data in real time, the low detection efficiency of multi-chamber has become a prominent bottleneck restricting the operation and maintenance efficiency.

[0003] Large GIS sites (such as 220kV substations) usually contain 40-50 chambers, and each chamber needs to be detected independently. The existing technology lacks centralized signal switching capability, and the operation and maintenance personnel must switch the online monitoring background interface one by one, or climb to the interface of each chamber to connect a handheld device. High-altitude operation is time-consuming, and the compact structure and high installation (≥10 meters) cause the need to call a high-altitude operation vehicle for single detection, and the whole station recheck takes more than 8 hours.

[0004] Early GIS does not have a pre-installed signal lead-out end, and external detection needs to temporarily lay an antenna, and the deployment time of a single chamber is generally more than 30 minutes. The signal-to-noise ratio of external non-contact detection (such as ultrasonic wave) is generally more than 30dB, the signal coupling efficiency is low, and multiple repeated measurements are needed to ensure accuracy, further slowing down the progress.

[0005] The existing GIS partial discharge detection technology has problems such as single-channel serial operation and high-altitude operation dependence, resulting in low GIS partial discharge detection efficiency. SUMMARY

[0006] The present application provides a GIS ultra-high frequency online monitoring device and method based on signal multiplexing, which can solve the problem of low GIS partial discharge detection efficiency caused by single-channel serial operation and high-altitude operation dependence of GIS partial discharge detection technology, and improve the detection efficiency of GIS partial discharge detection.

[0007] In a first aspect, the present application provides a GIS ultra-high frequency online monitoring device based on signal multiplexing, which comprises: an ultra-high frequency sensor arranged on the inner wall of each GIS chamber; a non-contact directional coupler arranged on the outer wall of each GIS chamber; a local detection box arranged on the ground in the area of each GIS chamber, the local detection box comprising a multi-channel intelligent switching matrix; and a double-layer shielding cable connected between each non-contact directional coupler and the multi-channel intelligent switching matrix; the multi-channel intelligent switching matrix intelligently switches the acquisition circuit under the control of a controller, couples with the ultra-high frequency sensor through the non-contact directional coupler, receives the ultra-high frequency signal, and returns to the controller through the double-layer shielding cable and the multi-channel intelligent switching matrix, thereby realizing the online monitoring of the partial discharge of multiple GIS chambers.

[0008] In a possible implementation, the local detection box further comprises a self-calibration module; the self-calibration module receives a reference signal of the portable detection device; and the ultra-high frequency signal is self-calibrated based on the reference signal.

[0009] In a possible implementation, the multi-channel intelligent switching matrix comprises a plurality of radio frequency relays, and each radio frequency relay corresponds to one non-contact coupler.

[0010] In a possible implementation, the inner layer of the double-layer shielding cable is an aluminum foil shielding layer, and the outer layer is a copper mesh shielding layer; the double-layer shielding cable is provided with a magnetic ring filter in sections, and the magnetic ring of the magnetic ring filter is made of a nickel-zinc ferrite and nanocrystalline composite material.

[0011] In a second aspect, the embodiment of the present application provides a GIS ultra-high frequency online monitoring method based on signal multiplexing, applied to an online monitoring device, the online monitoring device comprising: an ultra-high frequency sensor arranged on the inner wall of each GIS gas chamber, a non-contact directional coupler arranged on the outer wall of each GIS gas chamber, a multi-channel intelligent switching matrix arranged on the ground in the area where each GIS gas chamber is located, and a double-layer shielding cable connected between each non-contact directional coupler and the multi-channel intelligent switching matrix; the online monitoring method comprises: receiving a polling instruction, the polling instruction comprising identification information of an ultra-high frequency sensor of a GIS gas chamber to be detected; based on the polling instruction, switching the multi-channel intelligent switching matrix to the acquisition circuit where the ultra-high frequency sensor to be detected is located; acquiring the ultra-high frequency signal of the ultra-high frequency sensor to be detected through the non-contact directional coupler; and determining the partial discharge quantity of the GIS gas chamber to be detected based on the ultra-high frequency signal.

[0012] In a possible implementation, based on the ultra-high frequency signal, the partial discharge quantity of the GIS gas chamber to be detected is determined, comprising: extracting the spectral feature of the ultra-high frequency signal; the spectral feature comprises a main frequency band and a pulse width; based on the spectral feature of the ultra-high frequency signal, selecting a wavelet basis function; based on the wavelet basis function, performing wavelet decomposition on the ultra-high frequency signal to obtain a plurality of wavelet signals; calculating the noise standard deviation of each wavelet signal, and based on the noise standard deviation of each wavelet signal, determining the denoising threshold of each wavelet signal; based on the denoising threshold of each wavelet signal, denoising each wavelet signal to obtain a denoised wavelet signal; based on the denoised wavelet signal, synthesizing a denoised ultra-high frequency signal; and based on the denoised ultra-high frequency signal, determining the partial discharge quantity of the GIS gas chamber to be detected.

[0013] In a possible implementation, the method further includes: controlling the self-calibration module to output a standard pulse, the standard pulse being a pulse signal with a set amplitude and a set bandwidth; injecting the standard pulse into the target channel through the multi-channel intelligent switching matrix; recording output signals of the online monitoring device and the local detection box; calculating a dynamic error based on the standard pulse and the output signals of the online monitoring device and the local detection box; the dynamic error including a gain error and a time delay deviation; adjusting the local detection box based on the dynamic error to realize full-automatic calibration.

[0014] In a possible implementation, after adjusting the local detection box based on the dynamic error to realize full-automatic calibration, the method further includes: calculating a signal-to-noise ratio of the standard pulse based on the standard pulse and the output signals of the online monitoring device and the local detection box; dynamically updating an alarm threshold based on the signal-to-noise ratio of the standard pulse; the alarm threshold being used to determine whether each GIS gas chamber is working normally.

[0015] In a possible implementation, based on the polling instruction, switching the multi-channel intelligent switching matrix to the acquisition loop in which the to-be-detected UHF sensor is located includes: determining a radio frequency relay corresponding to the UHF sensor based on identification information of the UHF sensor in the polling instruction; driving the radio frequency relay corresponding to the UHF sensor to be turned on and controlling other relays to be turned off.

[0016] In a possible implementation, the method further includes: when detecting that the partial discharge amount of the target gas chamber exceeds the alarm threshold, triggering UHF signal acquisition of adjacent gas chambers of the target gas chamber; calculating signal time delay differences between the UHF signals of the adjacent gas chambers; determining a discharge source distance based on the signal time delay differences between the UHF signals of the adjacent gas chambers; the discharge source distance being a distance between a discharge source and a reference point of the gas chamber; if the discharge source distance is greater than a physical length of the gas chamber, it is determined that the discharge source distance is external electromagnetic interference; if the discharge source distance is less than or equal to the physical length of the gas chamber, it is determined that the discharge source distance is a real discharge inside the GIS.

[0017] In a third aspect, an electronic device is provided, which includes a memory and a processor, the memory storing a computer program, and the processor being configured to invoke and run the computer program stored in the memory to execute the steps of the method in the second aspect and any possible implementation manner of the second aspect.

[0018] In a fourth aspect, a computer readable storage medium is provided, which stores a computer program, and the computer program is configured to implement the steps of the method in the second aspect and any possible implementation manner of the second aspect when executed by a processor.

[0019] The application provides a GIS ultra-high frequency online monitoring device and method based on signal multiplexing, the online monitoring device is designed, the ultra-high frequency sensor is arranged on the inner wall of each GIS gas chamber, the non-contact directional coupler is arranged on the outer wall of each GIS gas chamber, the coupling of the non-contact directional coupler and the ultra-high frequency sensor is used to realize the transmission of the ultra-high frequency signal, the GIS gas chamber does not need to be perforated, and the partial discharge detection can be realized. The local detection box is arranged on the ground in the area where each GIS gas chamber is located, the non-contact directional coupler of each GIS gas chamber is connected through the multi-channel intelligent switching matrix in the local detection box, the polling switching detection of the partial discharge in each GIS gas chamber is realized, the operation of the maintenance personnel does not need to be climbed, and the problems, such as low GIS partial discharge detection efficiency caused by the single-channel serial operation of the GIS partial discharge detection technology and the dependence on high-altitude operation, are solved, and the detection efficiency of the GIS partial discharge detection is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0021] Figure 1 is a flow diagram of a GIS ultra-high frequency online monitoring method based on signal multiplexing provided by the embodiments of the present application;

[0022] Figure 2 is a structural diagram of an electronic device provided by the embodiments of the present application. DETAILED DESCRIPTION

[0023] In the following description, specific details are set forth such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, it should be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0024] In the description of the present application, unless otherwise specified, " / " means "or", for example, A / B can mean A or B. "And / or" in this paper is only a description of the association between the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, "at least one" "multiple" means two or more. "First", "second", etc. are not limited in quantity and execution order, and "first", "second", etc. are not necessarily different.

[0025] In the embodiments of the present application, the words "exemplary" or "for example" are used to mean serving as an example or illustration. Any embodiment or design presented as "exemplary" or "for example" in the embodiments of the present application is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the words "exemplary" or "for example" is intended to present concepts in a concrete manner, facilitating understanding of the related concepts.

[0026] In addition, the terms "comprising" and "having" and any variations thereof in the description of the present application are intended to cover the non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or modules is not limited to the listed steps or modules, but can optionally include other steps or modules not listed, or can optionally include other steps or modules inherent to the process, method, product or device.

[0027] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be described by specific embodiments in conjunction with the drawings of the present application.

[0028] The embodiment of the present application provides a GIS ultra-high frequency online monitoring device based on signal multiplexing. The online monitoring device comprises: an ultra-high frequency sensor arranged on the inner wall of each GIS gas chamber; a non-contact directional coupler arranged on the outer wall of each GIS gas chamber; a local detection box arranged on the ground in the area where each GIS gas chamber is located, the local detection box comprising a multi-channel intelligent switching matrix; and a double-layer shielding cable connected between each non-contact directional coupler and the multi-channel intelligent switching matrix.

[0029] The multi-channel intelligent switching matrix intelligently switches the acquisition loop under the control of the controller, couples with the ultra-high frequency sensor through the non-contact directional coupler, receives the ultra-high frequency signal, and transmits the signal back to the controller through the double-layer shielding cable and the multi-channel intelligent switching matrix, thereby realizing online monitoring of partial discharge of multiple GIS gas chambers.

[0030] In some embodiments, the non-contact directional coupler has a structural design: a capacitive coupling type antenna (size: Φ20mm*5mm) is used, a nanocrystalline magnetic core (magnetic permeability > 50,000) is embedded, and the antenna is directly attached to the outer wall of the GIS gas chamber without damaging the seal. Frequency response: 300MHz-3GHz (fluctuation <±1dB), coupling efficiency ≥85% (actual measurement compared with built-in sensor signal attenuation). Old equipment adaptation: fixed through a strong magnetic base, compatible with early GIS equipment without reserved interface.

[0031] In some embodiments, the local detection box further comprises a self-calibration module; the self-calibration module receives a reference signal of a portable detection device; and the ultra-high frequency signal is self-calibrated based on the reference signal.

[0032] Example deployment scheme of the ground detection box, protection level: IP65 housing (dustproof and waterproof), wide temperature design (-25℃~70℃). Human-computer interaction: 7-inch touch screen display real-time waveform + alarm state. Physical knob for emergency channel switching (redundant design).

[0033] In some embodiments, the multi-channel intelligent switching matrix includes a plurality of radio frequency relays, and the radio frequency relays correspond one-to-one to the non-contact couplers.

[0034] In some embodiments, the radio frequency relay array: Omron G6K-2F-RF (isolation > 80 dB @ 3 GHz, switching time < 10 ms) is selected, and a 32-input-to-1-output topology is supported. Remote control: integrated 4G / WiFi module (ESP32), supporting APP remote channel switching or starting timing polling (such as 30 seconds per channel sampling).

[0035] In some embodiments, the inner layer of the double-layer shielding cable is an aluminum foil shielding layer, and the outer layer is a copper mesh shielding layer; the double-layer shielding cable is provided with a magnetic ring filter in sections, and the magnetic ring of the magnetic ring filter is made of a nickel-zinc ferrite and nanocrystalline composite material.

[0036] Example: the inner layer is 0.025mm aluminum foil + 100% coverage, reflecting high-frequency interference (> 100MHz). The outer layer is 95% braided copper mesh (wire diameter 0.1mm). Absorbing low-frequency magnetic field (50Hz power frequency noise)

[0037] Example: scenario-based configuration of the magnetic ring filter, selection: nickel-zinc ferrite (Ni-Zn) magnetic ring (initial magnetic permeability μi=900), segmented and sleeved at both ends of the cable (distance from the coupler / detection box <0.5m). Winding method: 3 turns of the cable around the magnetic ring → impedance is raised to 300Ω@100MHz (only 100Ω for a single turn). Common-mode noise suppression > 15dB (compared with baseline data without magnetic ring installation).

[0038] The application provides a GIS ultra-high frequency online monitoring device based on signal multiplexing, through design of the online monitoring device, the ultra-high frequency sensor is arranged on the inner wall of each GIS gas chamber, the non-contact directional coupler is arranged on the outer wall of each GIS gas chamber, through coupling of the non-contact directional coupler and the ultra-high frequency sensor, the ultra-high frequency signal transmission is realized, without perforating the GIS gas chamber, the partial discharge detection can be realized. The local detection box is arranged on the ground in the area where each GIS gas chamber is located, the non-contact directional couplers of each GIS gas chamber are connected through the multi-channel intelligent switching matrix in the local detection box, the polling switching detection of the partial discharge in each GIS gas chamber is realized, without the operation and maintenance personnel climbing operation, the problems of low GIS partial discharge detection efficiency caused by GIS partial discharge detection technology single-channel serial operation, high-altitude operation dependence and the like are solved, and the detection efficiency of the GIS partial discharge detection is improved.

[0039] Based on the above online monitoring device, as shown in Figure 1 The application embodiment provides a GIS ultra-high frequency online monitoring method based on signal multiplexing.

[0040] S101, receiving a polling instruction.

[0041] In the application embodiment, the polling instruction includes identification information of the ultra-high frequency sensor of the GIS gas chamber to be detected.

[0042] Illustratively, the polling instruction is triggered in any of the following ways: a remote control instruction issued by a background monitoring system (transmitted to an embedded controller through a WiFi / 4G module); a timing inspection program preset in the local detection box (a periodic trigger signal is generated based on an internal RTC module of an STM32); an instant switching command initiated by an operator through a physical key or a touch screen.

[0043] Illustratively, the microcontroller extracts the sensor identification information (such as 16-bit encoding) in the instruction, matches a pre-stored GIS gas chamber topology mapping table, and determines the physical channel number of the target sensor in the relay matrix.

[0044] S102, based on the polling instruction, switching the multi-channel intelligent switching matrix to the acquisition circuit where the ultra-high frequency sensor to be detected is located.

[0045] As a possible implementation manner, the application embodiment can determine the radio frequency relay corresponding to the ultra-high frequency sensor based on the identification information of the ultra-high frequency sensor in the polling instruction; drive the radio frequency relay corresponding to the ultra-high frequency sensor to open, and control other relays to close.

[0046] Exemplarily, according to the parsed channel number, a low-level signal is sent to a drive circuit of a corresponding radio frequency relay to activate a coil magnetic circuit to make the contact closed; and drive signals of all other relays are synchronously closed to ensure that the channel isolation is greater than 80 dB, and signal crosstalk is avoided.

[0047] Exemplarily, a switching safety mechanism adopts a "break-before-make" timing control: a 5 ms reset pulse is sent to all relays before switching to ensure that the old channel is completely disconnected before the new channel is turned on; and a contact state is monitored in real time: the on-off state of the relay is fed back through an optical coupling isolation circuit, and if the switching is not completed within 10 ms, an abnormal alarm is triggered.

[0048] S103, through a non-contact directional coupler, a ultra-high frequency signal of a to-be-detected ultra-high frequency sensor is collected.

[0049] Exemplarily, a directional coupler is adaptively designed: for old GIS equipment without a reserved interface, a capacitive coupling antenna (frequency response range 300 MHz-3 GHz) is installed close to the built-in sensor area outside the GIS shell; through a ceramic insulation layer (dielectric constant ε_r≥9), non-invasive coupling of electromagnetic signals is realized to avoid SF6 gas leakage risk. Signal conditioning: the coupled signal is compensated for transmission loss through a preamplifier (gain 0-40 dB adjustable), and then enters a shielded cable through a 50 Ω impedance matching circuit.

[0050] Exemplarily, anti-interference transmission: the signal is transmitted to the ground detection box through a double-layer shielded cable (inner aluminum foil suppresses high-frequency interference, and outer copper mesh absorbs low-frequency noise); a nickel-zinc ferrite magnetic ring (wound 2-3 turns) is additionally installed in the middle of the cable to suppress signal distortion caused by common-mode noise.

[0051] S104, based on the ultra-high frequency signal, a partial discharge amount of the to-be-detected GIS gas chamber is determined.

[0052] As a possible implementation manner, step S104 can be specifically implemented as steps S1041-S1047.

[0053] S1041, a frequency spectrum feature of the ultra-high frequency signal is extracted.

[0054] In some embodiments, the frequency spectrum feature includes a main frequency band and a pulse width.

[0055] Exemplarily, main frequency band analysis: the original signal is subjected to 1024-point FFT transformation to extract a frequency band interval (such as 450 MHz±50 MHz) with an energy proportion greater than 80%; pulse width measurement: a high-speed ADC (sampling rate≥100 MS / s) is used to capture a rising edge of the signal, and a time corresponding to a 10%-90% amplitude is calculated as the pulse width.

[0056] S1042, select a wavelet basis function based on the spectral characteristics of the UHF signal.

[0057] For example, the dynamic selection of the wavelet basis function establishes a mapping rule between the spectral characteristics and the wavelet basis: if the main frequency band is greater than 1 GHz and the pulse width is less than 5 ns, select Db4 wavelet (time domain tight support characteristics adapt to narrow pulse); if the main frequency band is less than 500 MHz and the pulse width is greater than 20 ns, select Sym8 wavelet (better frequency domain resolution).

[0058] S1043, based on the wavelet basis function, wavelet decomposition is performed on the UHF signal to obtain a plurality of wavelet signals.

[0059] S1044, calculate the noise standard deviation of each wavelet signal, and determine the denoising threshold of each wavelet signal based on the noise standard deviation of each wavelet signal.

[0060] S1045, based on the denoising threshold of each wavelet signal, denoising is performed on each wavelet signal to obtain a denoised wavelet signal.

[0061] For example, hierarchical threshold denoising, 5-layer wavelet decomposition is performed on the signal, the noise standard deviation of each layer of detail coefficient is calculated, an adaptive threshold is generated, and hard threshold processing is performed on the high-frequency sub-band and soft threshold compression is performed on the low-frequency sub-band.

[0062] S1046, based on the denoised wavelet signal, a denoised UHF signal is synthesized.

[0063] S1047, based on the denoised UHF signal, the partial discharge quantity of the GIS gas chamber to be detected is determined.

[0064] For example, the denoised signal is reconstructed, the pulse amplitude and repetition frequency are extracted, the apparent discharge quantity is calculated through the calibration curve, the synchronous trigger reference pulse source (amplitude 50 mV / 10 ns) is injected into the detection circuit, and if the measured value deviation is greater than 5%, the k value is automatically corrected.

[0065] The present application provides a GIS UHF online monitoring method based on signal multiplexing, by designing an online monitoring device, setting a UHF sensor on the inner wall of each GIS gas chamber, and setting a non-contact directional coupler on the outer wall of each GIS gas chamber, through the coupling of the non-contact directional coupler and the UHF sensor, the UHF signal transmission is realized, without perforating the GIS gas chamber, the partial discharge detection is realized. And set a local detection box on the ground in the area where each GIS gas chamber is located, connect the non-contact directional coupler of each GIS gas chamber through the multi-channel intelligent switching matrix in the local detection box, realize the polling switching detection of the partial discharge in each GIS gas chamber, without the need for maintenance personnel to climb the operation, solve the problem of low efficiency of GIS partial discharge detection caused by single-channel serial operation of GIS partial discharge detection technology, high-altitude operation dependence, etc., improve the detection efficiency of GIS partial discharge detection.

[0066] Optionally, the GIS ultra-high frequency online monitoring method based on signal multiplexing provided by the embodiment of the application further comprises steps S201-S205.

[0067] S201, a standard pulse is output by a self-calibration module.

[0068] In some embodiments, the standard pulse is a pulse signal with a set amplitude and a set bandwidth.

[0069] For example, the pulse parameter configuration is as follows: the pulse parameters (amplitude range 1 mV-1V, pulse width 5 / 10 / 50 ns optional) are set through a detection box human-computer interface; a high-speed DAC chip (such as AD9102) receives digital instructions to generate corresponding analog pulse waveforms; an output end is coupled to a signal loop through a high-voltage ceramic capacitor (100 pF / 2 kV) to eliminate the influence of direct current bias.

[0070] For example, the trigger mechanism is as follows: timing trigger: calibration is automatically started at a low load period in the early morning every day; event trigger: calibration is forced when the environmental temperature fluctuation is greater than ±5°C or the system is restarted.

[0071] S202, the standard pulse is injected into a target channel through a multi-channel intelligent switching matrix.

[0072] For example, the channel switching control is as follows: a dedicated calibration channel is added in the switching matrix to direct the standard pulse into a target detection loop; a radio frequency relay is used to switch the path, and the switching delay is less than 10 ms; and an impedance matching is performed: a 50Ω resistor is connected in series with the pulse output end to ensure that the characteristic impedance is consistent with that of a coaxial cable (vswr<1.2).

[0073] S203, the output signals of the online monitoring device and the local detection box are recorded.

[0074] For example, the synchronous acquisition is as follows: the output signals of the online monitoring device and the local detection box are captured synchronously by high-speed ADCs (≥100 MS / s); a TTL trigger signal is generated at the rising edge of the standard pulse to realize time alignment of the two systems; and the pulse amplitude and the arrival time are recorded to a nonvolatile memory.

[0075] S204, a dynamic error is calculated based on the standard pulse and the output signals of the online monitoring device and the local detection box.

[0076] In some embodiments, the dynamic error includes a gain error and a time delay deviation.

[0077] For example, the gain error can be calculated by the following formula.

[0078]

[0079] Gin, Gout, and Gcal are the gain errors of the online monitoring device, the local detection box, and the self-calibration module, respectively.err Gain error, V ref Nominal amplitude of the standard pulse output, V local Nominal amplitude of the local detection box output.

[0080] Exemplarily, the time delay deviation can be calculated by the following formula.

[0081] Δt = |t online -t local |;

[0082] Wherein, Δr is the time delay deviation, t online is the arrival time of the online detection output signal; t local is the arrival time of the local detection box output signal.

[0083] Exemplarily, the embodiment of the application can calculate the signal-to-noise ratio (SNR) of the local detection box output signal, and if the SNR < 30 dB, it is determined that the transmission link is abnormal.

[0084] S205, based on the dynamic error, adjusting the local detection box to realize full-automatic calibration.

[0085] Exemplarily, the embodiment of the application can calculate the signal-to-noise ratio (SNR) of the standard pulse based on the standard pulse and the output signals of the online monitoring device and the local detection box; based on the signal-to-noise ratio of the standard pulse, dynamically updating the alarm threshold; the alarm threshold is used to determine whether each GIS gas chamber is working normally.

[0086] Exemplarily, gain calibration: if the gain error > 5%, the microcontroller automatically adjusts the detection channel LNA gain value (writes into the DAC register); time delay compensation: implanting a digital delay line in the FPGA to compensate for the subsequent detection signal. Threshold optimization: dynamically updating the alarm threshold according to the real-time SNR.

[0087] In this way, the embodiment of the application can perform self-calibration through the self-calibration module, and adjust the local detection box based on the dynamic error, thereby improving the accuracy of GIS gas chamber partial discharge detection.

[0088] Optionally, the GIS ultra-high frequency online monitoring method based on signal multiplexing provided by the embodiment of the application further comprises steps S301-S305.

[0089] S301, when detecting that the partial discharge amount of the target gas chamber exceeds the alarm threshold, triggering the ultra-high frequency signal collection of the adjacent gas chamber of the target gas chamber.

[0090] Exemplary target identification: when the partial discharge amount of the target gas chamber (A) exceeds the threshold, its physically adjacent gas chambers (B, C) are automatically searched; the adjacent sensor identifiers are determined through the GIS topological mapping table (e.g., the same interval gas chambers with a distance of less than 3 meters). Parallel acquisition: the switching matrix sequentially turns on the A, B, and C channels within 50 ms, and synchronously records the three UHF signals.

[0091] S302, calculating the signal time delay difference between the UHF signals of the adjacent gas chambers.

[0092] Exemplary feature point extraction: wavelet transform (Db4 base) is applied to each signal to extract the zero-crossing point timestamp of the first partial discharge pulse; the adjacent sensor time delay is calculated.

[0093] S303, determining the discharge source distance based on the signal time delay difference between the UHF signals of the adjacent gas chambers.

[0094] In some embodiments, the discharge source distance is the distance between the discharge source and the reference point of the gas chamber.

[0095] Exemplary discharge source distance can be calculated by the following formula.

[0096]

[0097] wherein d is the discharge source distance, v is the propagation speed of electromagnetic waves in the GIS gas chamber, Δt is the minimum time delay difference. min

[0098] S304, if the discharge source distance is greater than the physical length of the gas chamber, it is determined as external electromagnetic interference.

[0099] Exemplary determination as external electromagnetic interference indicates that the current alarm is a false alarm, and a suppression instruction needs to be sent to the online monitoring system to ignore the current alarm.

[0100] S305, if the discharge source distance is less than or equal to the physical length of the gas chamber, it is determined as a real discharge inside the GIS.

[0101] Exemplary determination as a real discharge inside the GIS indicates that the discharge position coordinates need to be uploaded to the operation and maintenance platform to trigger a red warning.

[0102] In this way, the present application can determine the discharge source position by joint detection between multiple gas chambers, accurately determine whether it is a false alarm, and realize dynamic linkage diagnosis of the GIS gas chamber by using the time difference positioning principle.

[0103] It should be understood that the size of the serial number of each step in the above embodiments does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. ​

[0104] The following is an apparatus embodiment of the present application, for details not described in detail, reference can be made to the corresponding method embodiments described above.

[0105] Figure 2 is a structural schematic diagram of an electronic device provided by an embodiment of the present application. The electronic device 400 includes a processor 401, a memory 402, and a computer program 403 stored in the memory 402 and executable on the processor 401. The processor 401 implements the steps in the above method embodiments when executing the computer program 403. Alternatively, the processor 401 implements the functions of each module / unit in the above apparatus embodiments when executing the computer program 403.

[0106] For example, the computer program 403 can be divided into one or more modules / units, which are stored in the memory 402 and executed by the processor 401 to complete the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program 403 in the electronic device 400.

[0107] The processor 401 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0108] The memory 402 can be an internal storage unit of the electronic device 400, such as a hard disk or a memory of the electronic device 400. The memory 402 can also be an external storage device of the electronic device 400, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, and the like equipped on the electronic device 400. Further, the memory 402 can include both an internal storage unit and an external storage device of the electronic device 400. The memory 402 is used to store the computer program and other programs and data required by the terminal. The memory 402 can also be used to temporarily store data that has been output or will be output.

[0109] The above-described embodiments are merely intended for describing the technical solutions of the present application, but not to limit the present application; even though the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A GIS UHF online monitoring device based on signal multiplexing, characterized in that, include: UHF sensors installed on the inner walls of each GIS air chamber; Non-contact directional couplers installed on the outer wall of each GIS air chamber; Local detection boxes are installed on the ground in the area where each GIS gas chamber is located. The local detection box includes a multi-channel intelligent switching matrix. And double-shielded cables connecting each non-contact directional coupler and the multi-channel intelligent switching matrix; The multi-channel intelligent switching matrix intelligently switches the acquisition loop under the control of the controller. It is coupled with the UHF sensor through a non-contact directional coupler to receive UHF signals and transmit them back to the controller through a double-shielded cable and the multi-channel intelligent switching matrix, realizing online monitoring of partial discharge in multiple GIS gas chambers.

2. The GIS UHF online monitoring device based on signal multiplexing according to claim 1, characterized in that, The local testing box also includes a self-calibration module; The self-calibration module receives a reference signal from the portable testing device and performs self-calibration on the UHF signal based on the reference signal.

3. The GIS UHF online monitoring device based on signal multiplexing according to claim 1, characterized in that, The multi-channel intelligent switching matrix includes multiple radio frequency relays, each corresponding to a non-contact coupler.

4. The GIS UHF online monitoring device based on signal multiplexing according to claim 1, characterized in that, The inner layer of the double-shielded cable is an aluminum foil shielding layer, and the outer layer is a copper mesh shielding layer; The double-shielded cable is equipped with magnetic ring filters in sections, and the magnetic ring material of the magnetic ring filter is a composite material of nickel-zinc ferrite and nanocrystalline material.

5. A GIS UHF online monitoring method based on signal multiplexing, characterized in that, An online monitoring device is applied to an online monitoring system, comprising: an ultra-high frequency sensor installed on the inner wall of each GIS air chamber; a non-contact directional coupler installed on the outer wall of each GIS air chamber; a multi-channel intelligent switching matrix installed on the ground in the area where each GIS air chamber is located; and a double-shielded cable connecting the non-contact directional coupler and the multi-channel intelligent switching matrix; the online monitoring method includes: Receive a polling command, the polling command including the identification information of the UHF sensor of the GIS air chamber to be detected; Based on the polling command, the multi-channel intelligent switching matrix is ​​switched to the acquisition circuit where the ultra-high frequency sensor to be detected is located; The ultra-high frequency signal of the ultra-high frequency sensor under test is acquired through a non-contact directional coupler; Based on the ultra-high frequency signal, the partial discharge quantity of the GIS air cell to be detected is determined.

6. The GIS UHF online monitoring method based on signal multiplexing according to claim 5, characterized in that, The determination of the partial discharge quantity of the GIS air cell to be detected based on the ultra-high frequency signal includes: Extract the spectral characteristics of the ultra-high frequency signal; the spectral characteristics include the main frequency band and the pulse width; Based on the spectral characteristics of the ultra-high frequency signal, wavelet basis functions are selected; Based on the wavelet basis function, the UHF signal is decomposed into multiple wavelet signals. Calculate the noise standard deviation of each wavelet signal, and determine the denoising threshold of each wavelet signal based on the noise standard deviation of each wavelet signal. Based on the denoising threshold of each wavelet signal, each wavelet signal is denoised to obtain the denoised wavelet signal. Based on the denoised wavelet signal, a denoised ultra-high frequency signal is synthesized. The partial discharge quantity of the GIS air cell to be detected is determined based on the denoised UHF signal.

7. The GIS UHF online monitoring method based on signal multiplexing according to claim 5, characterized in that, The method further includes: The self-calibration module outputs a standard pulse, which is a pulse signal with a set amplitude and a set bandwidth. Standard pulses are injected into the target channel using a multi-channel intelligent switching matrix; Record the output signals of the online monitoring device and the local detection box; Based on the standard pulse and the output signals of the online monitoring device and the local detection box, the dynamic error is calculated; the dynamic error includes gain error and time delay deviation. Based on the dynamic error, the local testing box is adjusted to achieve fully automatic calibration.

8. The GIS UHF online monitoring method based on signal multiplexing according to claim 7, characterized in that, After adjusting the local detection box based on the dynamic error to achieve fully automatic calibration, the process also includes: Based on the standard pulse and the output signals of the online monitoring device and the local detection box, the signal-to-noise ratio of the standard pulse is calculated; The alarm threshold is dynamically updated based on the signal-to-noise ratio of the standard pulse; the alarm threshold is used to determine whether each GIS gas chamber is working properly.

9. The GIS UHF online monitoring method based on signal multiplexing according to claim 5, characterized in that, The step of switching the multi-channel intelligent switching matrix to the acquisition loop of the ultra-high frequency sensor to be detected based on the polling command includes: Based on the identification information of the UHF sensor in the polling instruction, the radio frequency relay corresponding to the UHF sensor is determined; It drives the RF relay corresponding to the UHF sensor to turn on and controls other relays to turn off.

10. The GIS UHF online monitoring method based on signal multiplexing according to claim 5, characterized in that, The method further includes: When the partial discharge of the target air chamber exceeds the alarm threshold, the acquisition of ultra-high frequency signals from the adjacent air chambers of the target air chamber is triggered. Calculate the signal delay difference between the UHF signals of adjacent air chambers; The discharge power source distance is determined based on the signal delay difference between the ultra-high frequency signals of adjacent air chambers; the discharge power source distance is the distance between the discharge power source and the air chamber reference point. If the distance to the power source is greater than the physical length of the air chamber, it is determined to be external electromagnetic interference; If the discharge distance is less than or equal to the physical length of the gas chamber, it is determined to be a true discharge inside the GIS.

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