A partial discharge detection pressurization test method based on adaptive segmented variable parameters of oscillating wave

Abstract

The present application belongs to the technical field of electric power detection and test, and particularly relates to a method for detecting partial discharge of an oscillation wave based on self-adaptive segmented variable parameters, which comprises three-stage segmented voltage boosting strategies of a low-voltage pre-excitation stage, a medium-voltage pressure maintaining stage and a rated test stage for self-adaptive adjustment of parameters based on basic parameters of a cable to be detected; the three-stage segmented voltage boosting mode of low-voltage pre-excitation, medium-voltage pressure maintaining and rated test is adopted, and initial parameters can be matched according to basic parameters such as cable length, operation life and joint quantity; meanwhile, cable resonance frequency is tracked in real time, and loop inductance and capacitance are dynamically adjusted to realize impedance matching, so as to supplement excitation energy for old long cables and multi-joint cables, fully stimulate latent small defects and reduce the rate of missed detection; reasonable control of oscillation energy is realized for new cables and short cables, so as to avoid insulation damage caused by overvoltage excitation and solve the problem that traditional schemes cannot balance defect detection and insulation protection.

Description

Technical Field

[0001] This invention belongs to the field of power testing technology, specifically relating to a pressure test method for detecting partial discharge of oscillating waves based on adaptive segmented variable parameters. Background Technology

[0002] Currently, the power industry commonly uses a fixed-parameter pressurization mode for partial discharge detection tests. Testers pre-set fixed charging voltages, voltage ramp-up steps, oscillation frequencies, and holding times according to industry standards. These uniform test parameters are used to complete partial discharge excitation and signal acquisition for power cables of different models, lengths, and service lives. While this method is simple to operate and highly versatile, it has the following core drawbacks: Fixed parameters result in extremely poor test adaptability, failing to simultaneously achieve both sufficient defect excitation and insulation safety protection. Traditional fixed parameters cannot adapt to diverse cable conditions: for short or new cables, fixed test voltages are often too high, leading to excessive oscillation energy and potentially causing minor insulation damage, accelerating cable aging; for long-distance cables, old, damp cables, and cables with multiple joints, fixed parameters result in insufficient excitation energy, failing to effectively excite minute latent insulation defects, leading to a very high rate of missed detections. More critically, existing technologies maintain constant parameters throughout the entire process, lacking a mechanism for dynamic adjustment based on the cable's real-time oscillation response and insulation attenuation characteristics. This makes it impossible to simultaneously achieve both sufficient defect excitation and insulation safety protection during the same test, resulting in the long-standing industry problem of intact cables being damaged due to over-testing and defective cables being missed due to under-testing. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention provides a method, terminal, and storage medium for pressure testing of partial discharge detection of oscillating waves based on adaptive segmented variable parameters.

[0004] In a first aspect, the present invention provides a pressure test method for detecting partial discharge of oscillating waves based on adaptive piecewise variable parameters, comprising: S1. Collect the basic parameters of the cable under test and the field environmental parameters, calibrate the unloaded baseline and generate a dynamic interference threshold curve, and adaptively correct the dynamic interference threshold curve based on the field environmental parameters. S2. Based on the basic parameters of the cable under test, determine the initial test parameters, and apply oscillating wave excitation step by step using a segmented pressurization strategy that includes sequentially executing the low-voltage pre-excitation section, the medium-voltage holding section, and the rated test section; and during the pressurization process, detect the equivalent impedance of the cable in real time and track the cable resonant frequency, and dynamically adjust the oscillation circuit parameters to lock the circuit operating frequency at the resonant frequency; S3. During each round of oscillation wave excitation, the characteristic parameters of the oscillation circuit and the partial discharge signal parameters are collected synchronously. The noise discrimination of the partial discharge signal parameters is performed based on the dynamic interference threshold curve. The original partial discharge signal after discrimination is processed to extract the discharge type identification feature. The characteristic parameters of the oscillation circuit, the partial discharge signal parameters and the discharge type identification feature are timestamped and stored to form a feature data group. S4. Calculate the real-time comprehensive status assessment index based on the feature data group to determine the insulation status of the cable under test, and calculate the insulation aging index based on the cable operation parameters in the basic parameters of the cable under test and the feature data of the previous round; according to the insulation aging index and the real-time comprehensive status assessment index, coordinately correct the step size and oscillation frequency in the subsequent three-level segmented pressurization strategy and feed it back to step S2. S5. Preset fault shutdown criteria and qualified shutdown criteria. When the partial discharge signal parameter exceeds the preset threshold, the voltage boost will be stopped immediately and the test will be terminated. When there is no new partial discharge signal and the oscillation waveform is stable for several consecutive oscillation cycles, the test will be automatically terminated.

[0005] In a second aspect, the present invention provides a terminal, comprising: Processor, memory, among which, This memory is used to store computer programs. The processor is used to retrieve and run the computer program from memory, causing the terminal to perform the terminal method described above.

[0006] Thirdly, the present invention provides a computer storage medium storing instructions that, when executed on a computer, cause the computer to perform the methods described in the above aspects.

[0007] The beneficial effects of this invention are as follows: Employing a three-stage pressurization mode—low-voltage pre-excitation, medium-voltage holding, and rated test—it can match initial parameters based on fundamental parameters such as cable length, service life, and number of joints. Simultaneously, it tracks the cable resonant frequency in real time and dynamically adjusts the circuit inductance and capacitance to achieve impedance matching. For old, long cables and cables with multiple joints, it supplements the excitation energy to fully excite latent micro-defects and reduce the missed detection rate. For new and short cables, it reasonably controls the oscillation energy to avoid insulation damage caused by overvoltage excitation, fundamentally solving the problem of traditional solutions failing to balance defect detection and insulation protection.

[0008] Before the test, a dynamic interference threshold curve is generated through multi-gear low-voltage no-load oscillation, and adaptive correction is completed in combination with on-site environmental parameters such as temperature, humidity and electromagnetic interference; during the test, noise identification is completed relying on the threshold, then the partial discharge signal frequency band is separated through multi-layer wavelet decomposition, and a PRPD map is constructed to extract discharge features, so as to effectively strip on-site clutter interference, distinguish noise from real partial discharge signals, eliminate misjudgment, and improve the accuracy of partial discharge signal identification and analysis.

[0009] The present invention introduces two evaluation dimensions, namely a real-time comprehensive state assessment index and an insulation aging index, carries out multi-dimensional comprehensive judgment in combination with the real-time oscillation characteristics of the cable, partial discharge data, historical operation state and previous test data, cooperatively corrects the step-up step length and oscillation frequency according to the two indices, and forms closed-loop control of collection-analysis-evaluation-parameter adjustment. Compared with the traditional fixed parameter mode, the test rhythm can be intelligently adjusted according to the real-time state of cable insulation, so that the test parameters are always adapted to the current working condition of the cable.

[0010] Dual shutdown criteria for fault and qualification are set, and a dynamic safety margin is introduced at the same time, and four levels of states including green, yellow, orange and red are divided to realize multi-level early warning and classified disposal. It can not only perform emergency shutdown when an abnormal partial discharge signal is detected to prevent cable breakdown and fault expansion, but also automatically end the test when the cable insulation is qualified; the test safety boundary is dynamically monitored throughout the whole process to reduce manual intervention errors and comprehensively improve the test operation safety.

[0011] In addition, the present invention has reliable design principle, simple structure and very broad application prospect. Brief Description of the Drawings

[0012] To more clearly describe the technical solutions in the embodiments of the present invention or the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0013] Figure 1 is a schematic flowchart of a method according to an embodiment of the present invention.

[0014] Figure 2 is a schematic structural diagram of a terminal provided by an embodiment of the present invention. Detailed Description of the Embodiments

[0015] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0017] Figure 1 This is a schematic flowchart illustrating a pressure test method for detecting partial discharge of oscillating waves based on adaptive piecewise variable parameters, provided by the present invention. The order of the steps in this flowchart can be changed, and some steps can be omitted, depending on different requirements.

[0018] like Figure 1 As shown, the method includes: S1. Collect the basic parameters of the cable under test and the field environmental parameters, calibrate the unloaded baseline and generate a dynamic interference threshold curve, and adaptively correct the dynamic interference threshold curve based on the field environmental parameters. S2. Based on the basic parameters of the cable under test, determine the initial test parameters, and apply oscillating wave excitation step by step using a segmented pressurization strategy that includes sequentially executing the low-voltage pre-excitation section, the medium-voltage holding section, and the rated test section; and during the pressurization process, detect the equivalent impedance of the cable in real time and track the cable resonant frequency, and dynamically adjust the oscillation circuit parameters to lock the circuit operating frequency at the resonant frequency; S3. During each round of oscillation wave excitation, the characteristic parameters of the oscillation circuit and the partial discharge signal parameters are collected synchronously. The noise discrimination of the partial discharge signal parameters is performed based on the dynamic interference threshold curve. The original partial discharge signal after discrimination is processed to extract the discharge type identification feature. The characteristic parameters of the oscillation circuit, the partial discharge signal parameters and the discharge type identification feature are timestamped and stored to form a feature data group. S4. Calculate the real-time comprehensive status assessment index based on the feature data group to determine the insulation status of the cable under test, and calculate the insulation aging index based on the cable operation parameters in the basic parameters of the cable under test and the feature data of the previous round; according to the insulation aging index and the real-time comprehensive status assessment index, coordinately correct the step size and oscillation frequency in the subsequent three-level segmented pressurization strategy and feed it back to step S2. S5. Preset fault shutdown criteria and qualified shutdown criteria. When the partial discharge signal parameter exceeds the preset threshold, the voltage boost will be stopped immediately and the test will be terminated. When there is no new partial discharge signal and the oscillation waveform is stable for several consecutive oscillation cycles, the test will be automatically terminated.

[0019] To facilitate understanding of the present invention, the following description further illustrates the method for detecting partial discharge of oscillating waves based on adaptive segmented variable parameters, using the principle of the method and the process of conducting the test based on adaptive segmented variable parameters in the embodiments.

[0020] First, step S1 includes: S11. Enter the basic parameters of the cable under test, including the rated voltage level. Cable laying length L, number of intermediate joints Cable service life The type of insulation material and the type of installation environment were determined, and on-site environmental parameters, including ambient temperature (θ) and air humidity, were collected. On-site power frequency electromagnetic interference amplitude and the range of high-frequency noise interference bands ; S12. Disconnect the cable under test from the test host, set the k-level gradient low-voltage no-load oscillation, and the i-th level no-load oscillation voltage is... ,in Acquire the ambient noise signal under no-load conditions. Based on the background noise signal mean and standard deviation Generate dynamic interference threshold curve: ; in, Let t be the dynamic disturbance threshold at time t; Here is the confidence coefficient, and its value range is... ; S13. Dynamic interference threshold curve based on on-site environmental parameters Adaptive correction is performed to generate the corrected dynamic interference threshold curve: ; in, This is the corrected dynamic interference threshold; The reference ambient temperature; Reference air humidity; The reference power frequency electromagnetic interference amplitude; These are the correction weighting coefficients for temperature, humidity, and electromagnetic interference, respectively, with values ​​ranging from [value range missing]. Corrected dynamic interference threshold curve This is used for noise discrimination of partial discharge signal parameters in subsequent step S3.

[0021] The test host (i.e., the oscillating wave partial discharge detection device) is the test equipment for performing oscillating wave partial discharge detection. The test host includes a high-voltage DC power supply, a variable inductor, a variable capacitor, a high-voltage electronic switch, and a signal acquisition unit. The high-voltage DC power supply is used to charge the cable under test. The variable inductor and variable capacitor form an adjustable resonant oscillation circuit. The high-voltage electronic switch is used to control the start and stop of the discharge oscillation. The signal acquisition unit is used to acquire the oscillation waveform and the partial discharge signal.

[0022] Secondly, step S2 includes: S21. Rated voltage level based on the basic parameters of the cable under test. Cable laying length L, cable service life and the number of intermediate joints Initial matching of initial test parameters, including initial charging voltage. and fundamental oscillation frequency The initial charging voltage Adjustments based on cable length and service life; fundamental oscillation frequency. Equivalent inductance of the oscillating circuit and equivalent capacitance based on cable length Jointly determined: ; ; in, This is the rated oscillation wave test voltage; Based on cable length L and service life Voltage correction factor, ; , Capacitance per unit length of cable For loop stray capacitance; S22. Based on the initial test parameters, perform three-stage pressure application sequentially: low-voltage pre-excitation stage, medium-voltage holding stage, and rated test stage. The low-voltage pre-excitation stage uses pre-excitation voltage. The first round of shockwave excitation was carried out, among which Collect the first round of oscillation waveform and obtain the initial attenuation coefficient. and loop quality factor The medium-pressure holding section is based on the initial attenuation coefficient. and loop quality factor Increase the voltage to the preset medium-voltage holding voltage. The partial discharge pulse was observed under stable voltage, and the voltage was gradually increased to the rated oscillation wave test voltage in the rated test section. ; S23. During the entire three-stage segmented pressurization process, the equivalent impedance of the cable is monitored in real time. The cable resonant frequency is determined by frequency scanning within a preset frequency band. Dynamically adjust the variable inductance of the oscillation circuit and variable capacitor This locks the circuit's operating frequency to the resonant frequency. And achieve impedance matching, where the variable inductor and variable capacitor The adjustment formula is: ; ; in, Parasitic inductance of the circuit; Temperature compensation capacitor. Based on the ambient temperature θ and reference temperature collected in step S1 Adaptive compensation is performed for the deviation, resonant frequency The tracking results are fed back in real time to the voltage adjustment process of the three-stage segmented voltage application, realizing the coordinated adaptation of the oscillation circuit parameters and the segmented voltage application strategy.

[0023] Among them, based on the initial attenuation coefficient and loop quality factor Calculate the medium-voltage holding voltage : ; in, This is the pre-excitation voltage for the low-voltage pre-excitation section; Based on the boost step size; Used as a reference attenuation coefficient; The reference circuit quality factor; This is the attenuation coefficient weighting coefficient. ; This is the quality factor weighting coefficient. .

[0024] when and When this occurs, it indicates that the cable insulation is in good condition, allowing for a significant voltage increase. Take the higher value; when or This indicates that the cable has energy loss or insulation deterioration, and voltage should be increased with caution. Take the lower value.

[0025] The high-voltage DC power supply of the oscillating wave partial discharge detection device is controlled by the adjusted charging voltage. The cable under test is charged, and after charging is complete, a high-voltage electronic switch is triggered to generate a damped oscillating wave; a medium-voltage holding voltage is maintained. Maintain The duration of stable oscillation, including the holding time Based on the initial attenuation coefficient Dynamically determined: ; in, Basic pressure holding time; This is the extension factor for the medium-pressure holding section. When the attenuation coefficient When the voltage is large, the holding time is automatically extended to fully observe the partial discharge signal.

[0026] In addition, step S3 includes: S31. During each round of oscillation wave excitation, the characteristic parameters of the oscillation circuit and the partial discharge signal parameters are collected synchronously. The characteristic parameters of the oscillation circuit include the real-time oscillation wave attenuation coefficient. Oscillation period Circuit quality factor and voltage amplitude fluctuation The partial discharge signal parameters include the amplitude of the high-frequency partial discharge pulse. Pulse count Pulse growth rate and pulse distribution phase characteristics ; S32. Based on the corrected dynamic interference threshold curve generated in step S1 Noise discrimination is performed on the partial discharge signal parameters to eliminate noise that has an amplitude lower than the corrected dynamic interference threshold. The noise interference signal retains an amplitude higher than the corrected dynamic interference threshold. The effective partial discharge pulse signal is used to obtain the filtered original partial discharge signal. ; S33. The original partial discharge signal after identification. J-level wavelet decomposition is performed to separate the partial discharge signal components of different frequency bands. The wavelet decomposition formula is as follows: ; in, For the wavelet detail coefficients of the j-th layer, corresponding to the partial discharge signal component of the j-th frequency band; Here are the wavelet approximation coefficients for the J-th level; J is the decomposition level, 3≤J≤6; based on the energy proportion of each frequency band after decomposition. Construct PRPD maps and extract discharge type identification features, energy percentage of each frequency band. The calculation formula is: ; S34. The characteristic parameters of the oscillation circuit are... The parameters of the identified partial discharge signal PRPD spectrum and discharge type identification features by timestamp Aligned storage to form the characteristic data set of the m-th oscillation. : ; in, The PRPD (Phase Resolved Partial Discharge) spectrum of the m-th oscillation; Identify the characteristic quantity for the discharge type of the m-th oscillation; The timestamp of the m-th oscillation, feature data group Used in subsequent step S4 to calculate the real-time comprehensive condition assessment index and insulation aging index.

[0027] Next, step S4 includes: S41. Feature data group formed based on step S3 The real-time comprehensive state assessment index for the m-th oscillation is calculated using the characteristic parameters of the oscillation loop and the partial discharge signal parameters. Real-time comprehensive status assessment index The calculation formula is: ; in, The real-time attenuation coefficient for the m-th round; Let m be the quality factor of the m-th cycle. The m-th round of partial discharge pulses; The pulse growth rate in the m-th round; The distortion coefficient of the oscillation waveform in the m-th round; Identify the characteristic quantity for the discharge type of the m-th round; Used as a reference attenuation coefficient; For reference quality factors; Reference partial discharge pulse count; The reference pulse growth rate; Let be the weighting coefficient, satisfying ; S42. Based on the real-time comprehensive state evaluation index of the m-th oscillation. To determine the insulation condition of the cable under test, when If the insulation condition is determined to be good, the voltage increase step size will be automatically increased and the voltage holding time will be shortened. The threshold for good insulation condition; the corrected boost step size. for: ; when If a latent defect is detected, the boost rate is automatically slowed down and the oscillation excitation duration is extended. Latent defect threshold; corrected holding time for: ; in, Based on the boost step size; For acceleration coefficient, ; As a reference state assessment index; Basic pressure holding time; For the extension factor, ; S43. Service life based on the basic parameters of the cable under test. and number of intermediate joints Combined with the average decay coefficient in the feature data set of the previous rounds and cumulative partial discharge pulse count Calculate the insulation aging index of the m-th oscillation. Insulation aging index The calculation formula is: ; in, Let be the weighting coefficient, satisfying ; For reference operating years; For reference number of connectors; Reference partial discharge pulse count; The reference cable length is L; the cable laying length is L. S44, Based on the insulation aging index of the m-th round. Compared with the real-time comprehensive status assessment index of the mth round The boost step size and oscillation frequency are collaboratively corrected in multiple dimensions to generate optimized experimental parameters, which are then fed back to step S2. The collaboratively corrected boost step size... and oscillation frequency The calculation formula is: ; ; in, The boost step size for the m-th round is the boost step size after real-time state assessment index correction; This represents the current oscillation frequency in the m-th round. For reference aging index; As a reference state assessment index; The coefficient is the collaborative correction factor, and its value range is [missing value]. Optimized test parameters include the co-corrected boost step size. and oscillation frequency .

[0028] Finally, step S5 includes: S51. Set fault shutdown criteria and monitor the pulse growth rate in the partial discharge signal parameters collected in step S3 in real time. and partial discharge pulse amplitude When the pulse growth rate Exceeding the preset threshold or partial discharge pulse amplitude Continuously exceeding the amplitude threshold Reaching the preset time Immediately stop the voltage increase and terminate the test, where the pulse growth rate... and amplitude threshold The calculation formula is: ; ; in, The cumulative number of partial discharge pulses at time t; The corrected dynamic interference threshold curve generated in step S1; This is the amplitude threshold coefficient. ; S52. Set qualified shutdown criteria, based on the oscillation circuit characteristic parameters and partial discharge signal parameters in the characteristic data group formed in step S3, to determine continuous shutdown. The test automatically terminates when there are no new partial discharge pulses and the oscillation waveform is stable and distortion-free within a complete oscillation cycle, based on the variation of partial discharge pulses and the stability of the oscillation waveform. The formula for determining the qualified shutdown criterion is as follows: ; ; in, To determine the start time; To determine the number of consecutive cycles, ; The oscillation period; Let be the distortion coefficient of the oscillation waveform at time t; This is the waveform distortion threshold. S53. During the execution of fault shutdown criteria and qualified shutdown criteria, the dynamic safety margin is calculated in real time. Dynamic safety margin The dynamic safety margin is the relative safe distance between the real-time test voltage and the breakdown voltage estimated based on the insulation aging index calculated in step S4. and estimated breakdown voltage The calculation formula is: ; ; in, Let be the real-time test voltage at time t; The reference breakdown voltage for the new cable; This is the aging degradation coefficient. / Year; Let be the insulation aging index at time t; The environmental temperature influence coefficient. θ represents the ambient temperature collected in step S1. Reference temperature; S54, Based on dynamic safety margin Implement multi-level early warning and shutdown control, when When the condition is determined to be green and normal, the test continues. When the system is in a yellow alert state, the rate of pressure increase is slowed down. When the situation is determined to be an orange warning state, the pressure increase is suspended and the pressure holding observation is extended. When a red emergency state is declared and an immediate shutdown is triggered, multi-level early warning shutdown control, along with fault shutdown criteria and qualified shutdown criteria, are executed in concert to achieve closed-loop safety control throughout the entire test process; among which, The threshold for the green normal state is... The threshold for a yellow attention state is... The threshold for the orange warning status.

[0029] Figure 2 This is a schematic diagram of a terminal 300 provided in an embodiment of the present invention. The terminal 300 can be used to execute the oscillating wave partial discharge detection pressure test method based on adaptive segmented variable parameters provided in the embodiment of the present invention.

[0030] The terminal 300 may include a processor 310, a memory 320, and a communication module 330. These components communicate via one or more buses. Those skilled in the art will understand that the server structure shown in the figure does not constitute a limitation of the present invention. It may be a bus topology or a star topology, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0031] The memory 320 can be used to store the execution instructions of the processor 310. The memory 320 can be implemented by any type of volatile or non-volatile memory terminal or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. When the execution instructions in the memory 320 are executed by the processor 310, the terminal 300 is able to perform some or all of the steps in the above method embodiments.

[0032] The processor 310 serves as the control center of the storage terminal, connecting various parts of the electronic terminal via various interfaces and lines. It executes software programs and / or modules stored in the memory 320, and calls data stored in the memory to perform various functions of the electronic terminal and / or process data. The processor can be composed of integrated circuits (ICs), such as a single packaged IC or multiple packaged ICs with the same or different functions connected together. For example, the processor 310 may consist only of a central processing unit (CPU). In this embodiment of the invention, the CPU may have a single processing core or include multiple processing cores.

[0033] The communication module 330 is used to establish a communication channel, enabling the storage terminal to communicate with other terminals. It receives user data sent by other terminals or sends user data to other terminals.

[0034] The present invention also provides a computer storage medium, wherein the computer storage medium may store a program, which, when executed, may include some or all of the steps provided in the embodiments of the present invention. The storage medium may be a magnetic disk, an optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0035] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium such as a USB flash drive, mobile hard drive, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, or other media capable of storing program code. It includes several instructions to cause a computer terminal (which may be a personal computer, server, or a second terminal, network terminal, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0036] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A pressure test method for detecting partial discharge of oscillating waves based on adaptive piecewise variable parameters, characterized in that, include: S1. Collect the basic parameters of the cable under test and the field environmental parameters, calibrate the unloaded baseline and generate a dynamic interference threshold curve, and adaptively correct the dynamic interference threshold curve based on the field environmental parameters. S2. Based on the basic parameters of the cable under test, determine the initial test parameters, and apply oscillating wave excitation step by step using a segmented pressurization strategy that includes sequentially executing the low-voltage pre-excitation section, the medium-voltage holding section, and the rated test section; and during the pressurization process, detect the equivalent impedance of the cable in real time and track the cable resonant frequency, and dynamically adjust the oscillation circuit parameters to lock the circuit operating frequency at the resonant frequency; S3. During each round of oscillation wave excitation, the characteristic parameters of the oscillation circuit and the partial discharge signal parameters are collected synchronously. The noise discrimination of the partial discharge signal parameters is performed based on the dynamic interference threshold curve. The original partial discharge signal after discrimination is processed to extract the discharge type identification feature. The characteristic parameters of the oscillation circuit, the partial discharge signal parameters and the discharge type identification feature are timestamped and stored to form a feature data group. S4. Calculate the real-time comprehensive status assessment index based on the feature data group to determine the insulation status of the cable under test, and calculate the insulation aging index based on the cable operation parameters in the basic parameters of the cable under test and the feature data of the previous round; according to the insulation aging index and the real-time comprehensive status assessment index, coordinately correct the step size and oscillation frequency in the subsequent three-level segmented pressurization strategy and feed it back to step S2. S5. Preset fault shutdown criteria and qualified shutdown criteria. When the partial discharge signal parameter exceeds the preset threshold, the voltage boost will be stopped immediately and the test will be terminated. When there is no new partial discharge signal and the oscillation waveform is stable for several consecutive oscillation cycles, the test will be automatically terminated.

2. The method for detecting partial discharge of oscillating waves under pressure based on adaptive piecewise variable parameters according to claim 1, characterized in that, Step S1 includes: S11. Input the basic parameters of the cable under test, including rated voltage level, cable laying length, number of intermediate joints, cable service life, insulation material type and laying environment type, and collect on-site environmental parameters, including ambient temperature, air humidity, on-site power frequency electromagnetic interference amplitude and high frequency noise interference frequency band range. S12. Disconnect the cable under test from the test host, set the k-level gradient low-voltage no-load oscillation, and the i-th level no-load oscillation voltage is... ,in The system collects the ambient background noise signal under no-load conditions and generates a dynamic interference threshold curve based on the mean and standard deviation of the ambient noise signal. S13. Based on the on-site environmental parameters, the dynamic interference threshold curve is adaptively corrected to generate the corrected dynamic interference threshold curve.

3. The method for detecting partial discharge of oscillating waves under pressure based on adaptive piecewise variable parameters according to claim 2, characterized in that, Step S2 includes: S21. Based on the rated voltage level, cable laying length, cable service life and number of intermediate joints in the basic parameters of the cable under test, the initial test parameters are initially matched, including the initial charging voltage and the basic oscillation frequency. The initial charging voltage is corrected according to the cable length and service life, and the basic oscillation frequency is determined by the equivalent inductance of the oscillation circuit and the equivalent capacitance based on the cable length. S22. Based on the initial test parameters, the three-stage pressure increase is performed sequentially: low-voltage pre-excitation stage, medium-voltage holding stage, and rated test stage. In the low-voltage pre-excitation stage, the pre-excitation voltage is used for the first round of oscillation wave excitation. The first round of oscillation waveform is collected and the initial attenuation coefficient and circuit quality factor are obtained. In the medium-voltage holding stage, the voltage is increased to the preset medium-voltage holding voltage based on the initial attenuation coefficient and circuit quality factor, and the partial discharge pulse is observed while maintaining the voltage. In the rated test stage, the voltage is gradually increased to the rated oscillation wave test voltage. S23. During the entire process of three-stage segmented pressurization, the equivalent impedance of the cable is detected in real time. The resonant frequency of the cable is determined by frequency scanning within a preset frequency range. The variable inductance and variable capacitance of the oscillation circuit are dynamically adjusted to lock the circuit operating frequency at the resonant frequency and achieve impedance matching.

4. The method for detecting partial discharge of oscillating waves under pressure based on adaptive piecewise variable parameters according to claim 3, characterized in that, Step S3 includes: S31. During each round of oscillation wave excitation, the characteristic parameters of the oscillation circuit and the partial discharge signal parameters are collected synchronously. The characteristic parameters of the oscillation circuit include the real-time oscillation wave attenuation coefficient, oscillation period, circuit quality factor and voltage amplitude fluctuation. The partial discharge signal parameters include the high-frequency partial discharge pulse amplitude, pulse number, pulse growth rate and pulse distribution phase characteristics. S32. Based on the modified dynamic interference threshold curve generated in step S1, noise discrimination is performed on the partial discharge signal parameters. Noise interference signals with amplitudes lower than the modified dynamic interference threshold are removed, and effective partial discharge pulse signals with amplitudes higher than the modified dynamic interference threshold are retained to obtain the discriminated original partial discharge signal. S33. Perform J-level wavelet decomposition on the identified partial discharge raw signal to separate the partial discharge signal components of different frequency bands; construct a PRPD spectrum based on the energy proportion of each frequency band after decomposition and extract discharge type identification features: S34. Store the oscillation circuit characteristic parameters, the identified partial discharge signal parameters, the PRPD spectrum and the discharge type identification characteristic quantities in alignment with the timestamps to form the characteristic data group of the m-th oscillation.

5. The method for detecting partial discharge of oscillating waves under pressure based on adaptive piecewise variable parameters according to claim 4, characterized in that, Step S4 includes: S41. Calculate the real-time comprehensive state evaluation index of the m-th oscillation based on the oscillation loop characteristic parameters and partial discharge signal parameters in the characteristic data group formed in step S3. ; S42. Based on the real-time comprehensive status assessment index To determine the insulation condition of the cable under test, when If the insulation condition is determined to be good, the voltage increase step size will be automatically increased and the voltage holding time will be shortened. The threshold for good insulation condition; when If a latent defect is detected, the boost rate is automatically slowed down and the oscillation excitation duration is extended. This is the threshold for latent defects; S43. Based on the service life and number of intermediate joints in the basic parameters of the cable under test, and combined with the average attenuation coefficient and cumulative partial discharge pulse number in the characteristic data group of the previous round, calculate the insulation aging index of the m-th round of oscillation. ; S44, Based on the insulation aging index of the m-th round. Compared with the real-time comprehensive status assessment index of the mth round The boost step size and oscillation frequency are adjusted in multiple dimensions to generate optimized test parameters and feed them back to step S2.

6. The method for detecting partial discharge of oscillating waves under pressure based on adaptive piecewise variable parameters according to claim 5, characterized in that, Real-time comprehensive status assessment index The calculation formula is: ； in, The real-time attenuation coefficient for the m-th round; Let m be the quality factor of the m-th cycle. The m-th round of partial discharge pulses; The pulse growth rate in the m-th round; The distortion coefficient of the oscillation waveform in the m-th round; Identify the characteristic quantity for the discharge type of the m-th round; Used as a reference attenuation coefficient; For reference quality factors; Reference partial discharge pulse count; The reference pulse growth rate; Let be the weighting coefficient, satisfying .

7. The method for detecting partial discharge of oscillating waves under pressure based on adaptive piecewise variable parameters according to claim 5, characterized in that, The boost step size after the m-th round of collaborative correction and oscillation frequency The calculation formula is: ； ； in, The boost step size for the m-th round is the boost step size after real-time state assessment index correction; This represents the current oscillation frequency in the m-th round. For reference aging index; As a reference state assessment index; The coefficient is the collaborative correction factor, and its value range is [missing value]. Optimized test parameters include the co-corrected boost step size. and oscillation frequency .

8. The method for detecting partial discharge of oscillating waves under pressure based on adaptive piecewise variable parameters according to claim 5, characterized in that, Step S5 includes: S51. Set fault shutdown criteria, monitor the pulse growth rate and partial discharge pulse amplitude in the partial discharge signal parameters collected in step S3 in real time, and immediately stop the voltage boost and terminate the test when the pulse growth rate exceeds the preset threshold or the partial discharge pulse amplitude continues to exceed the amplitude threshold for a preset time. S52. Set qualified shutdown criteria, based on the oscillation circuit characteristic parameters and partial discharge signal parameters in the characteristic data group formed in step S3, to determine continuous shutdown. The test automatically terminates when there are no new partial discharge pulses and the oscillation waveform is stable and without distortion within a complete oscillation cycle. S53. During the execution of fault shutdown criteria and qualified shutdown criteria, the dynamic safety margin is calculated in real time. Dynamic safety margin The relative safe distance between the real-time test voltage and the breakdown voltage estimated based on the insulation aging index calculated in step S4; S54, Based on dynamic safety margin Implement multi-level early warning and shutdown control, when When the condition is determined to be green and normal, the test continues. When the system is in a yellow alert state, the rate of pressure increase is slowed down. When the situation is determined to be an orange warning state, the pressure increase is suspended and the pressure holding observation is extended. When a red emergency state is declared and an immediate shutdown is triggered, multi-level early warning shutdown control, along with fault shutdown criteria and qualified shutdown criteria, are executed in concert to achieve closed-loop safety control throughout the entire test process; among which, The threshold for the green normal state is... The threshold for a yellow attention state is... The threshold for the orange warning status.

9. A terminal, characterized in that, include: processor; Memory used to store the processor's execution instructions; The processor is configured to perform the method of any one of claims 1-8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-8.

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