A submarine cable joint quality detection method and device

Abstract

The application relates to a submarine cable joint quality detection method and device, relates to the technical field of power tool detection, and can improve the quality detection efficiency of the fusion interface of the power submarine cable. The method comprises the following steps: acquiring the partition recovery current of the submarine cable joint in a depolarization state; wherein the partition recovery current comprises a measurement electrode recovery current, a first protection electrode recovery current, a second protection electrode recovery current and a background current; the measurement electrode recovery current is compensated and stripped according to the first protection electrode recovery current, the second protection electrode recovery current and the background current, so that the effective recovery current corresponding to the fusion interface region is obtained; quality characteristics are extracted from the effective recovery current, and the quality detection result of the submarine cable joint is determined based on the quality characteristics.

Description

Technical Field

[0001] This application relates to the field of electrical appliance testing technology, and in particular to a method, apparatus, computer equipment, computer-readable storage medium, and computer program product for testing the quality of submarine cable joints. Background Technology

[0002] High-voltage DC submarine cable flexible joints are a key component in the manufacturing and connection of long-length submarine cables. They are usually formed through processes such as melting and hot pressing of insulating materials, and the quality of their interface bonding directly determines the long-term operational reliability of the entire submarine cable system.

[0003] However, in the actual manufacturing process of hot-press cross-linking, due to limitations in the construction environment and process fluctuations, the molten interface of flexible joints is prone to introducing micro-gaps, impurity contamination, or local microscopic electrical defects such as insufficient bonding strength. These defects, under the long-term action of a high-voltage DC electric field, can induce severe interfacial charge accumulation and local field strength distortion, thereby significantly increasing the risk of insulation breakdown. Existing conventional non-destructive testing methods such as ultrasound and X-rays are mainly sensitive to macroscopic structures or geometric deformations, while methods such as cross-section microscopy are destructive. Conventional overall macroscopic insulation performance testing is also prone to masking weak local anomalies.

[0004] Therefore, how to accurately detect local micro-defects at the molten interface without cutting or stripping the main insulation of the flexible joint is a technical problem that urgently needs to be solved in the field of submarine cable insulation condition testing. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer equipment, computer-readable storage medium, and computer program product for inspecting the quality of submarine cable joints, in response to the above-mentioned technical problems.

[0006] In a first aspect, this application provides a method for inspecting the quality of a submarine cable joint, wherein a measuring electrode is disposed in the molten interface region of the submarine cable joint to be inspected, and a first protective electrode and a second protective electrode are respectively disposed on both sides of the measuring electrode; the method includes:

[0007] The partition recovery current of the submarine cable joint in the depolarized state is obtained; wherein, the partition recovery current includes the recovery current of the measuring electrode, the recovery current of the first protection electrode, the recovery current of the second protection electrode, and the background current;

[0008] Based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, the recovery current of the measuring electrode is compensated and stripped to obtain the effective recovery current corresponding to the molten interface region;

[0009] Quality features are extracted from the effective recovery current, and the quality inspection results of the submarine cable joint are determined based on the quality features.

[0010] In one embodiment, the step of performing a compensation stripping process on the measuring electrode recovery current based on the first protective electrode recovery current, the second protective electrode recovery current, and the background current to obtain the effective recovery current corresponding to the molten interface region includes:

[0011] Obtain the first protection current compensation coefficient corresponding to the first protection electrode and the second protection current compensation coefficient corresponding to the second protection electrode;

[0012] The recovery current of the first protective electrode is weighted according to the first protection current compensation coefficient to obtain the first protection compensation component, and the recovery current of the second protective electrode is weighted according to the second protection current compensation coefficient to obtain the second protection compensation component.

[0013] The effective recovery current is obtained by removing the first protection compensation component, the second protection compensation component, and the background current from the recovery current from the measuring electrode.

[0014] In one embodiment, the quality characteristics include at least two of the following: short-term relaxation characteristics, long-term charge release characteristics, and charge release difference characteristics;

[0015] The extraction of quality features from the effective recovery current includes at least two of the following processes:

[0016] From the effective recovery current, extract the short-time relaxation feature used to characterize the charge release time of the shallow traps in the molten interface region;

[0017] From the effective recovery current, extract the long-term released charge used to characterize the amount of deep trapped charge released in the molten interface region;

[0018] Based on the decay trend of the effective recovery current within a preset short-time window and a long-time window, the charge release difference characteristics are determined.

[0019] In one embodiment, the decay trend is characterized by a short-time window decay index and a long-time window decay index;

[0020] The determination of the charge release difference characteristics based on the decay trend of the effective recovery current within a preset short-time window and a long-time window includes:

[0021] The effective recovery current is subjected to double log-linear fitting within the short time window to obtain the short time window decay index;

[0022] The effective recovery current is subjected to double log-linear fitting within the long time window to obtain the long time window decay index;

[0023] The difference between the short-time window decay index and the long-time window decay index is obtained, and the charge release difference characteristics are determined based on the difference.

[0024] In one embodiment, determining the quality inspection result of the submarine cable joint based on the quality characteristics includes:

[0025] If the short-term relaxation characteristic and the charge release difference characteristic satisfy the first characteristic change condition, and the long-term charge release does not satisfy the second characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be an air gap type fusion defect; or,

[0026] If the long-term released charge satisfies the second characteristic change condition, and the charge release difference characteristic does not satisfy the first characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be a contamination-type fusion defect; or,

[0027] If the short-term relaxation characteristic, the long-term charge release characteristic, and the charge release difference characteristic all satisfy the third characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be a composite fusion defect.

[0028] In one embodiment, determining the quality inspection result of the submarine cable joint based on the quality characteristics includes:

[0029] The fused quality feature vector corresponding to the submarine cable joint to be detected is obtained by combining the short-term relaxation feature, the long-term charge release feature, and the charge release difference feature.

[0030] The fused quality feature vector is matched with a pre-established defect calibration database to obtain the calibration matching result of the fused quality feature vector in the defect calibration database;

[0031] Based on the calibration and matching results, the quality inspection results of the submarine cable joint are determined.

[0032] In one embodiment, before obtaining the partition recovery current of the submarine cable joint to be tested in the depolarized state, the method further includes:

[0033] During the process of applying a DC polarization voltage between the cable conductor and the shielding layer of the submarine cable joint, the submarine cable joint is controlled to be at a preset test temperature.

[0034] When the submarine cable joint is at the preset test temperature and the DC polarization voltage is applied for a preset polarization time, the DC polarization voltage is cut off, triggering the submarine cable joint to enter the depolarization state, so as to obtain the partition recovery current of the submarine cable joint to be tested in the depolarization state.

[0035] Secondly, this application also provides a submarine cable joint quality inspection device, wherein a measuring electrode is provided in the molten interface region of the submarine cable joint to be inspected, and a first protective electrode and a second protective electrode are respectively provided on both sides of the measuring electrode.

[0036] The device includes:

[0037] The recovery current acquisition module is used to acquire the partitioned recovery current of the submarine cable joint in the depolarized state; wherein, the partitioned recovery current includes the measurement electrode recovery current, the first protection electrode recovery current, the second protection electrode recovery current, and the background current;

[0038] An effective current acquisition module is used to perform compensation and stripping processing on the recovery current of the measuring electrode based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, so as to obtain the effective recovery current corresponding to the molten interface region.

[0039] The detection result determination module is used to extract quality features from the effective recovery current and determine the quality detection result of the submarine cable joint based on the quality features.

[0040] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0041] The partition recovery current of the submarine cable joint in the depolarized state is obtained; wherein, the partition recovery current includes the recovery current of the measuring electrode, the recovery current of the first protection electrode, the recovery current of the second protection electrode, and the background current;

[0042] Based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, the recovery current of the measuring electrode is compensated and stripped to obtain the effective recovery current corresponding to the molten interface region;

[0043] Quality features are extracted from the effective recovery current, and the quality inspection results of the submarine cable joint are determined based on the quality features.

[0044] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0045] The partition recovery current of the submarine cable joint in the depolarized state is obtained; wherein, the partition recovery current includes the recovery current of the measuring electrode, the recovery current of the first protection electrode, the recovery current of the second protection electrode, and the background current;

[0046] Based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, the recovery current of the measuring electrode is compensated and stripped to obtain the effective recovery current corresponding to the molten interface region;

[0047] Quality features are extracted from the effective recovery current, and the quality inspection results of the submarine cable joint are determined based on the quality features.

[0048] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0049] The partition recovery current of the submarine cable joint in the depolarized state is obtained; wherein, the partition recovery current includes the recovery current of the measuring electrode, the recovery current of the first protection electrode, the recovery current of the second protection electrode, and the background current;

[0050] Based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, the recovery current of the measuring electrode is compensated and stripped to obtain the effective recovery current corresponding to the molten interface region;

[0051] Quality features are extracted from the effective recovery current, and the quality inspection results of the submarine cable joint are determined based on the quality features.

[0052] The aforementioned submarine cable joint quality inspection method, apparatus, computer equipment, computer-readable storage medium, and computer program product acquire the partitioned recovery current of the submarine cable joint in a depolarized state. This partitioned recovery current includes the recovery current of the measuring electrode, the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current. Based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, a compensation stripping process is performed on the recovery current of the measuring electrode to obtain the effective recovery current corresponding to the molten interface region. Quality features are extracted from the effective recovery current, and based on these features, the quality inspection result of the submarine cable joint is determined. In this application, by arranging partitioned loops in the molten interface region and specific spaces on both sides of the submarine cable joint, and utilizing the acquired currents of the protective electrodes on both sides and the background current, a quantitative compensation stripping process is performed on the measuring electrode current, which contains multiple stray signals. Without cutting or stripping the main insulation of the flexible joint, the effective recovery current signal dominated by the molten interface is extracted from the strong interference environment, effectively eliminating the superimposed interference of insulation discharge and surface leakage current on both sides. Furthermore, by extracting and comparing quality features, the quality inspection result of the submarine cable joint is determined, thereby improving the accuracy of the quality inspection of the molten interface of the submarine cable joint. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a test circuit diagram of a submarine cable joint quality inspection method in one embodiment;

[0055] Figure 2 This is a schematic diagram of the axial arrangement of the molten interface region in a submarine cable joint quality inspection method in one embodiment;

[0056] Figure 3 This is a flowchart illustrating a method for inspecting the quality of submarine cable joints in one embodiment;

[0057] Figure 4 This is a flowchart illustrating the method for inspecting the quality of submarine cable joints in another embodiment;

[0058] Figure 5 This is a structural block diagram of a submarine cable joint quality inspection device in one embodiment;

[0059] Figure 6 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0061] This application provides an application environment for a submarine cable joint quality inspection method, primarily involving non-destructive testing and evaluation of the insulation condition of high-voltage DC submarine cable accessories. In this environment, the core inspection object is typically the finished DC submarine cable flexible joint, which contains a fused interface region formed through processes such as hot-pressing the melting of insulating materials. The fusion quality of this region directly affects the long-term reliability of the submarine cable system. To conduct quality assessment without damaging or cutting the main insulation structure of the finished submarine cable joint, this application environment typically deploys a hardware architecture with zoned protection testing and a corresponding data processing terminal. This environment can be widely applied to various industrial testing scenarios, including factory acceptance testing, type testing, qualification testing, and engineering verification of DC submarine cable flexible joints.

[0062] For example, in a real-world detection physical environment, such as Figure 1 As shown, to simulate real operating conditions, the cable body and joint area are equipped with current-carrying heating devices, heating belts, and temperature sensors, thereby maintaining the entire test area in a controlled thermal state of 40 to 80 degrees Celsius. Measurement electrodes for capturing target signals are deployed in the axial region outside the submarine cable joint, corresponding to the internal molten interface. Simultaneously, first and second protective electrodes are arranged on the extended regions on both sides of the measurement electrodes, as detailed below. Figure 2 As shown. These electrode devices can be connected to monitoring equipment with multi-channel synchronous acquisition capabilities. In the critical power supply and electrical circuits, the test circuit includes a high-voltage positive output terminal (HV+), a high-voltage negative terminal (HV-), and a common low-voltage reference terminal (COM). The high-voltage polarization line is only connected to the internal conductor of the cable; during polarization, the HV+ terminal is directly connected to the cable conductor to provide high-voltage output; during depolarization, the cable conductor is connected to the COM terminal via a current-limiting discharge branch. Simultaneously, the measuring electrodes and the protective electrodes on both sides enter different channels of the acquisition terminal (e.g., CH-M acquires the measuring current, CH-G1 / G2 acquires the protective current). The reference terminal, HV- terminal, and discharge branch of all acquisition channels are uniformly connected to the common low-voltage reference terminal COM, and none of the electrodes in the circuit are directly grounded. When the submarine cable connector undergoes certain pre-processing electrical operations and enters the depolarization state, the acquisition equipment can synchronously acquire weak zone recovery current signals from each electrode channel. These signals not only contain the current in the target area but also the recovery current of the protective electrodes used for subsequent comparison and the ambient background current.

[0063] Furthermore, the application environment also includes a control terminal (or data analysis server, cloud processing platform, etc.) that communicates with the aforementioned acquisition terminal. This terminal receives the multi-channel depolarized zone recovery current data acquired above. Through a built-in analysis algorithm, based on the recovery current acquired by the two protective electrodes and the background current, the current of the measuring electrodes is compensated and stripped to eliminate interference from surface leakage and non-target areas. This process reconstructs the effective recovery current that is truly dominated by the molten interface. Based on this effective recovery current, relevant quality characteristics are extracted, and the quality inspection results of the submarine cable joint are automatically deduced and determined. This achieves a complete intelligent application closed loop from data acquisition and interference stripping to quality evaluation.

[0064] In one exemplary embodiment, such as Figure 3 As shown, a method for inspecting the quality of submarine cable joints is provided. Taking the application of this method to the control terminal in the above embodiment as an example, the method includes the following steps S301 to S303. Wherein:

[0065] The partition recovery current of the submarine cable joint in the depolarized state is obtained; wherein, the partition recovery current includes the recovery current of the measuring electrode, the recovery current of the first protection electrode, the recovery current of the second protection electrode, and the background current.

[0066] Among them, the depolarization state can be the electrical recovery stage in which the internal charge of the submarine cable joint begins to be released and tends to balance after the external excitation voltage is removed after a certain period of DC voltage polarization. It can be a key time window that reflects the characteristics of traps and defects inside the insulating medium.

[0067] The zone recovery current can be a collective term for multi-channel transient current signals synchronously acquired by an array of mutually isolated electrodes deployed at specific locations on the submarine cable joint under this depolarization state. The measurement electrode recovery current can be the current induced and captured by electrodes arranged in the axial region of the molten interface of the submarine cable joint, primarily used to characterize the charge release behavior of the target interface region. The first and second protection electrode recovery currents can be currents derived from shielding and protection devices arranged in the extended regions on both sides of the measurement electrodes, including leakage current along the cable surface and current responses in non-target areas such as the transition zones on both sides of the joint. The background current can be a weak fundamental current caused by objective factors such as environmental electromagnetic interference or the background noise of the test equipment in the depolarization acquisition circuit. It can usually be obtained by pre-recording under wiring conditions identical to the actual measurement without applying a DC polarization voltage, or by synchronous real-time acquisition using idle blank channels in the acquisition equipment. The aforementioned current data can be a digital time sequence obtained by analog-to-digital conversion of analog signals using a multi-channel acquisition device.

[0068] Specifically, after the external environment and measurement circuit of the submarine cable joint to be tested are ready, the partition recovery current of the submarine cable joint in the depolarized state is synchronously acquired through the data acquisition channels connected to each electrode. In actual execution, since the submarine cable joint spontaneously releases the charge captured by the insulation layer after the polarization voltage is removed, the measurement electrode in the molten interface area of ​​the flexible joint will extract the measurement electrode recovery current in real time. At the same time, the first and second protective electrodes distributed on both sides of the measurement electrode synchronously intercept the stray current flowing through the surface and the release current to the lateral non-core area, and output the first and second protective electrode recovery currents respectively, and simultaneously record the background current under the current environment. Through multi-channel synchronous data access and acquisition, the strict alignment of the acquired partition recovery current in the time dimension is ensured.

[0069] Optionally, to obtain the aforementioned high-precision current data without damaging or stripping the main insulation structure of the submarine cable, the measuring electrodes and the first and second protective electrodes on both sides can be electrically led out non-destructively through the reserved shielding layer lead-out end around the flexible joint, the outer shielding overlap area, or the segmented grounding point of the metal sheath. Alternatively, they can be tightly fitted using external temporary clamping ring electrodes, flexible conductive strips, or elastic conductive rings. Furthermore, during data access and acquisition, the relevant multi-channel acquisition circuits can employ a shielded structure with separate measuring, protective, and grounding ends to minimize the impact of surface leakage and stray coupling currents on extremely weak measurement results from the hardware level. When acquiring the partitioned recovery current, a higher initial acquisition time window can be set to capture the rapid transient release response in the early stages of depolarization. Subsequently, the sampling interval is dynamically adjusted according to the current decay rate, thereby optimizing overall computing resources while ensuring data integrity.

[0070] Step S302: Based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, the recovery current of the measuring electrode is compensated and stripped to obtain the effective recovery current corresponding to the molten interface region.

[0071] Among them, the effective recovery current can be time-series data reflecting the characteristics of the release of trapped charges in the molten interface region inside the submarine cable joint after eliminating stray components such as external electromagnetic interference and current leakage in non-target areas under depolarized conditions.

[0072] Compensation stripping is a data purification mechanism based on multi-channel reference signals to suppress interference and subtract background noise from the target acquisition signal. It is primarily used to remove non-target electrical responses caused by cable insulation, transition zones on both sides, and surface leakage from the recovered current of the original measuring electrodes, which contains various aliased components, thereby restoring a high-purity target interface signal. In practical industrial testing scenarios, this purification process can be implemented in various forms, such as time-domain adaptive proportional subtraction, multivariate regression analysis, or specific digital filtering algorithms.

[0073] Specifically, the total transient current induced by the measuring electrodes directly positioned around the molten interface inevitably contains bypass components flowing along the cable insulation surface and relaxation charges dissipated from surrounding non-core areas. Directly using the raw data for analysis would lead to serious deviations in subsequent quality assessments. Therefore, by introducing the synchronously acquired recovery current of the dual-sided protective electrodes as a leakage reference benchmark for non-target areas, and using the background current as an environmental test noise benchmark, redundant and interference components in the measuring electrode recovery current are dynamically subtracted at the data processing level, thereby reconstructing an effective recovery current that more accurately reflects the molten interface under test.

[0074] Optionally, when performing the compensation stripping process, the actual arrangement dimensions of the protective electrodes on both sides of the submarine cable joint, the equivalent impedance difference of the measurement circuit, and the electromagnetic environment of the test site can be comprehensively considered. The corresponding proportional adjustment factors can be adaptively matched for the recovery current of the first and second protective electrodes, thereby eliminating the influence of lateral leakage point by point on the continuous data points in the time domain in a weighted cancellation manner. In addition, frequency domain analysis technology can be combined to jointly filter the periodic power frequency interference and equipment thermal noise in the background current, so as to ensure that the effective recovery current obtained by the final stripping not only eliminates lateral interference in the macroscopic amplitude, but also has an extremely high data signal-to-noise ratio in the microscopic signal waveform.

[0075] Step S303: Extract quality features from the effective recovery current, and determine the quality inspection results of the submarine cable joint based on the quality features.

[0076] Among them, the quality characteristics can be based on the high-purity recovery current obtained after compensation stripping treatment. These characteristics can be extracted through processes such as time domain analysis, waveform fitting, or signal conversion. They are a series of evaluation indicators that can characterize the charge release behavior and trap energy level state of the internal insulating medium of the submarine cable joint. These indicators serve as the basis for subsequent quantitative analysis to determine the integrity of the internal dielectric structure and insulation performance of the flexible joint. Their specific forms can be expressed as time constant, charge accumulation, or mathematical characteristic values ​​that reflect the attenuation law.

[0077] The quality inspection results can be qualitative or quantitative conclusions about the fusion state of the submarine cable joint's molten interface after a comprehensive evaluation based on the above quality characteristics. These conclusions reflect the current insulation health level of the flexible joint and can be expressed as a specific quality grade classification scale or a diagnostic report for a specific interface defect type.

[0078] Specifically, since the reconstructed effective recovery current better reflects the microscopic polarization and depolarization response at the core molten interface, the waveform variation trend, amplitude decay rate, and accumulated charge release dynamics of this continuous current time series data at different time scales can be analyzed to accurately extract quality characteristics reflecting the distribution of shallow or deep traps within the interface. Subsequently, the extracted quality characteristics in each dimension are comprehensively compared and analyzed with benchmark data under healthy insulation conditions or a pre-set evaluation database to determine the current quality inspection results of the submarine cable joint.

[0079] Optionally, when extracting quality features, in addition to relying on direct fitting and calculation of time-domain waveforms, wavelet transform or frequency domain analysis can be combined to extract energy density features of specific frequency bands as a reference dimension for quality characterization. Simultaneously, in the stage of determining quality detection results based on quality features, an initial evaluation model constructed based on algorithms such as logistic regression, support vector machines, or cluster analysis can be introduced. Through nonlinear classification mapping of various feature signals in multidimensional space, a health status diagnostic conclusion, including confidence level, can be directly output. This processing method can flexibly adapt to submarine cable joints of different production batches, specifications, or service years, achieving intelligent analysis of the internal micro-interface state without damaging the cable's structure.

[0080] In this embodiment, by arranging partitioned circuits in specific spaces on both sides of the molten interface region of the submarine cable joint, and using the acquired protective electrode currents and background currents on both sides, quantitative compensation and stripping processing is performed on the measuring electrode current, which is mixed with multiple stray signals. Without cutting or stripping the main insulation of the flexible joint, the effective recovery current signal dominated by the molten interface is extracted from the strong interference environment, effectively eliminating the superposition interference of insulation discharge on both sides and surface leakage current. Then, by extracting and comparing quality features, the quality inspection result of the submarine cable joint is determined, thereby improving the accuracy of the quality inspection of the molten interface of the submarine cable joint.

[0081] In one embodiment, the recovery current of the measuring electrode is compensated and stripped based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current to obtain the effective recovery current corresponding to the molten interface region, including:

[0082] Obtain the first protection current compensation coefficient corresponding to the first protection electrode and the second protection current compensation coefficient corresponding to the second protection electrode; perform weighted processing on the recovery current of the first protection electrode according to the first protection current compensation coefficient to obtain the first protection compensation component, and perform weighted processing on the recovery current of the second protection electrode according to the second protection current compensation coefficient to obtain the second protection compensation component; remove the first protection compensation component, the second protection compensation component and the background current from the recovery current of the measured electrode to obtain the effective recovery current.

[0083] Among them, the first protection current compensation coefficient and the second protection current compensation coefficient can be dimensionless scaling factors used to quantify and correct the degree of influence of the two protective electrodes on the lateral leakage of the central measurement area during the signal reconstruction process of the recovery current. They can be used to adjust the deduction weight of the protection circuit current during the data processing stage. They can be obtained based on the calibration test of the healthy submarine cable flexible joint, the geometric capacitance model of the joint structure, the finite element electric field simulation analysis, or through dynamic calibration methods such as short-time background test under non-polarization voltage and repeated test fitting under multiple identical conditions.

[0084] The first and second protection compensation components can be reference bias data obtained by weighting the corresponding compensation coefficients mentioned above with the synchronously acquired recovery currents of the first and second protection electrodes, respectively. These components represent the quantitative estimate of stray currents that actually penetrate into the measuring electrode channel from the non-target areas on both sides of the flexible joint along the insulation surface or internal transition zone under the current test environment. Specifically, after obtaining the partitioned recovery current of the submarine cable joint in the depolarized state, the first protection current compensation coefficient corresponding to the first protection electrode and the second protection current compensation coefficient corresponding to the second protection electrode are obtained. The recovery current of the first protection electrode is weighted according to the first protection current compensation coefficient to obtain the first protection compensation component, and the recovery current of the second protection electrode is weighted according to the second protection current compensation coefficient to obtain the second protection compensation component. Then, the first protection compensation component, the second protection compensation component, and the background current are removed from the measuring electrode recovery current to obtain the effective recovery current. This weighted calculation method can adaptively address structural asymmetry or impedance differences that may exist on both sides of the submarine cable joint during actual installation.

[0085] Optionally, when performing the background current removal operation, considering the possible slight differences in hardware equivalent impedance or gain between the background acquisition channel and the measurement channel, a corresponding background current compensation coefficient can be obtained. After the background current is weighted based on the background current compensation coefficient to obtain the background compensation component, the background compensation component is then stripped from the current recovered from the measurement electrode, thereby further improving the accuracy of background noise reduction.

[0086] For example, the above-mentioned compensation stripping process can be implemented through a specific derivation formula, namely, the effective recovery current (corresponding to the dominant recovery current of the reconstructed molten interface) satisfies the following formula:

[0087] The formula is: i_f(t) = i_m(t) - a_1 * i_g1(t) - a_2 * i_g2(t) - i_b(t). In this formula, i_f(t) represents the final reconstructed effective recovery current time sequence; i_m(t) is the original acquired measurement electrode recovery current; i_g1(t) and i_g2(t) are the first and second protection electrode recovery currents acquired at the corresponding times, respectively; i_b(t) is the background current under the current depolarization environment (or the weighted background current if the optional weighting step mentioned above is performed); a_1 and a_2 represent the first and second protection current compensation coefficients, respectively. By introducing this stripping formula, at each discrete sampling time node in the depolarization stage, the system uses the original acquired signal as a basis and precisely and directionally subtracts the lateral leakage components on both sides and the basic environmental noise according to a determined ratio, thereby effectively weakening the response of non-target areas and obtaining a recovery current dominated by the local response of the molten interface.

[0088] In this embodiment, a weighted stripping operation using compensation coefficients enables refined modeling and quantitative subtraction of the complex stray current distribution on both sides of the flexible connector. Compared to conventional direct subtraction denoising, this method considers the asymmetric leakage phenomena caused by electrode placement deviations and differences in the transition structure of the semiconducting layers on both sides, which are very likely to occur in actual engineering sites. This makes the effective recovery current obtained from the stripping more faithfully approximate the true microscopic physical state of the molten interface, greatly improving the purity of the target signal and providing rigorous and high signal-to-noise ratio mathematical calculation support for subsequent accurate extraction.

[0089] In one embodiment, the quality characteristics include at least two of the following: short-time relaxation characteristics, long-time charge release characteristics, and charge release difference characteristics;

[0090] Extracting quality features from the effective recovery current includes at least two of the following processes:

[0091] Short-term relaxation characteristics for the charge release time of shallow traps in the molten interface region are extracted from the effective recovery current; long-term release charges for the amount of trapped charges released in deep traps in the molten interface region are extracted from the effective recovery current; and charge release difference characteristics are determined based on the decay trend of the effective recovery current within a preset short-term and long-term window.

[0092] Among them, the short-time relaxation feature can be the time constant or decay coefficient extracted based on the rapid decay stage of the effective recovery current in the early stage of depolarization. It is mainly used to quantitatively characterize the charge release time scale at shallow traps or weak bonding interfaces in the melt interface region of submarine cable joints.

[0093] Long-term charge release can be the charge data obtained by integrating or accumulating the effective recovery current over a long depolarization time period. It is mainly used to characterize the total amount of charge slowly released by deep traps or contaminants inside the interface.

[0094] The charge release difference characteristic can be a dimensionless mathematical index that reflects the change of the decay law of current across time scales. It is usually generated based on the comparison of the decay trend of current signal under different time windows. It is used to characterize the width of the trap energy level distribution or the turning point of the decay mechanism. In specific engineering applications, it can be reflected as specific parameters such as the dual-time-window power-law turning point index.

[0095] Specifically, the quality characteristics include at least two of the following: short-time relaxation characteristics, long-time released charge, and charge release difference characteristics. After obtaining the purified signal, the quality characteristics are extracted from the effective recovery current, which may include at least two processing logics: on the one hand, short-time relaxation characteristics are extracted from the effective recovery current to characterize the charge release time of shallow traps in the molten interface region; on the other hand, long-time released charge is extracted from the effective recovery current to characterize the amount of charge released by deep traps in the molten interface region. In addition, the charge release difference characteristics can be determined by capturing the slope or decay rate changes of the signal at different time periods based on the continuous decay trend of the effective recovery current within a preset short time window and a long time window.

[0096] For example, in conjunction with the actual physical depolarization process of submarine cable joints, the extraction of the above features can be achieved by relying on specific mathematical characterization parameters. For short-time relaxation features, the short-time relaxation time constant (denoted as τ_s) of the initial stage of the recovery current curve can be extracted to accurately characterize the rapid de-trapping behavior of shallow trap charges caused by weak interfacial bonding or micro-air gaps; for long-time release charges, the long-time release charge amount (denoted as Q_L) can be obtained by time integration of the effective recovery current waveform within a longer time window, thereby reflecting the slow and persistent electrolytic accumulation effect of deep trap regions introduced by impurity contamination or cross-linking byproducts; for charge release difference features, the characterization of the decay trend can be concretized as a dual-time-window power-law transition index (denoted as Δn), which can keenly capture the deep-seated changes in the current decay mechanism during the transition from shallow trap dominance to deep trap dominance in the entire depolarization process.

[0097] In this embodiment, by extracting multi-dimensional quality features covering short-time relaxation, long-time discharge, and discharge differences from the effective recovery current, a single one-dimensional time-series current signal can be transformed into a multi-dimensional quantitative index of insulation state with clear microscopic physical meaning. This fully decouples the charge dynamic behavior of shallow and deep traps inside the molten interface. This not only provides a key quantitative analysis anchor for subsequent fine differentiation of interface fusion defects with different physical mechanisms such as air gap type and contamination type, but also enhances the accuracy of perception of the evolution of tiny interface defects.

[0098] In one embodiment, the decay trend is characterized by a short-time window decay index and a long-time window decay index;

[0099] Based on the decay trend of the effective recovery current within a preset short-time window and a long-time window, the characteristics of charge release differences are determined, including:

[0100] The effective recovery current is subjected to double log-linear fitting within a short time window to obtain the short-time window decay index; the effective recovery current is subjected to double log-linear fitting within a long time window to obtain the long-time window decay index; the difference between the short-time window decay index and the long-time window decay index is obtained, and the charge release difference characteristics are determined based on the difference.

[0101] Among them, the short time window decay index can be the rate of decay of the effective recovery current with time extracted based on a mathematical fitting algorithm within a specific short time interval in the early stage of depolarization. It can usually reflect the dynamic characteristics of the shallow trap charge release stage.

[0102] The long-time window decay index can be a parameterized characterization of the effective recovery current decay rate over a relatively long time interval in the later stage of depolarization, and can be used to characterize the decay law in the stage of slow release of deep trap or interface polarization charge.

[0103] Double logarithmic linear fitting is a mathematical process that maps a nonlinear power-law decaying signal into a linear relationship. By performing logarithmic transformations on the time and current amplitudes in the time series data, and then using a linear regression algorithm to find the slope of the best-fitting line, the slope can reflect the power-law decay characteristics of the signal at a specific scale.

[0104] For example, by combining the physical depolarization process of the submarine cable joint, after obtaining the time-series curve of the effective recovery current, a specific period in the early stage of depolarization can be selected as a short time window, and the middle and late stages of depolarization can be selected as a long time window. Within these two independent time slices, the system converts the effective recovery current amplitude and the corresponding time to a double logarithmic coordinate system and performs linear fitting using methods such as least squares. The slope of the fitted line for the short time window is the short-time window power-law decay exponent, and the slope of the fitted line for the long time window is the long-time window power-law decay exponent. Furthermore, the slopes of the two are subtracted, and the difference is extracted as the dual-time-window power-law transition exponent (Δn), which quantitatively describes the transition change of the recovery current decay mechanism across time scales and the relative width of the trap energy level distribution.

[0105] In this embodiment, by performing double logarithmic linear fitting on the effective recovery current within different time windows and calculating the difference, the microscopic transition characteristics of the charge release process at the molten interface from shallow trap dominance to deep trap dominance are effectively amplified. This also minimizes the random interference that may be caused by absolute amplitude fluctuations at a single acquisition moment, enhances the sensitivity to capturing abnormal changes in the width of the microscopic trap energy level distribution, and enables more accurate identification of complex interface fusion defects.

[0106] In one embodiment, the quality inspection results for the submarine cable joint are determined based on quality characteristics, including:

[0107] If the short-term relaxation characteristic and the charge release difference characteristic satisfy the first characteristic change condition, and the long-term charge release does not satisfy the second characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be an air gap type fusion defect; or, if the long-term charge release satisfies the second characteristic change condition, and the charge release difference characteristic does not satisfy the first characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be a contamination type fusion defect; or, if the short-term relaxation characteristic, the long-term charge release, and the charge release difference characteristic all satisfy the third characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be a composite type fusion defect.

[0108] Among them, the first feature change condition, the second feature change condition, and the third feature change condition can be quantitative comparison benchmarks pre-set for different dimensions of quality characteristics in the quality evaluation process. They are used to reflect the degradation direction of the microstructure of the internal insulating medium of the flexible joint by judging whether the extracted feature data has an abnormal shift.

[0109] Air gap type fusion defects can be physical cavity defects formed during the melting and hot pressing process of submarine cable joints due to poor interface adhesion or the presence of micro air bubbles, which manifests as an increase in shallow trap density; contamination type fusion defects can be a type of defect formed by the accumulation of impurities, conductive particles or cross-linking byproducts at the interface due to improper control of the production environment, which manifests as the introduction of deep trap energy levels; composite type fusion defects can be a high-risk interface state with a relatively high risk of insulation failure due to the simultaneous presence of multiple adverse physical phenomena mentioned above.

[0110] It should be noted that the "air gap type fusion defect," "contamination type fusion defect," or "composite type fusion defect" determined based on the aforementioned characteristic change conditions in this application embodiment refers to the deterministic detection classification label output by the system based on the feature extraction algorithm. In engineering physics, this label indicates that the probability of the corresponding type of defect existing inside the submarine cable joint is extremely high (i.e., a suspected corresponding defect). Due to the objective physical characteristics of non-destructive testing, this detection result is mainly used to provide a basis for high-confidence diagnosis and maintenance early warning of cables.

[0111] For example, combining the physical diagnostic mechanism of submarine cable joints, the above-mentioned various changing conditions can be visualized as specific deviations of characteristic parameters from normal healthy baseline values. In actual logical judgment, if the values ​​of the short-time relaxation time constant (τ_s) and the dual-time-window power-law transition index (Δn) increase significantly (i.e., the first characteristic change condition is met), while the long-time release charge (Q_L) does not increase significantly (i.e., the second characteristic change condition is not met), it indicates that the interface charge release is mainly dominated by shallow traps, which physically corresponds to rapid discharge behavior at small air gaps or weak bonding surfaces. Therefore, the current result can be judged as a suspected air gap type fusion defect. Conversely, if the integral of the long-time release charge (Q_L) increases significantly (i.e., the second characteristic change condition is met), while the value of the long-time release charge (Q_L) does not increase significantly (i.e., the second characteristic change condition is met), while the value of the long-time release charge (Q_L) reflecting the transition behavior does not increase significantly, the long-time release charge (Q_L) does not increase significantly. If n remains at a low level (i.e., the first characteristic change condition is not met), it indicates that there are a large number of deep traps inside the interface that trap charges and release them slowly. This is physically consistent with the characteristics of deep-level traps introduced by contamination impurities. Therefore, the current result is determined to be a suspected contamination-type fusion defect. Furthermore, if multiple characteristic quantities such as τ_s, Δn, and Q_L are detected to increase abnormally at the same time (i.e., all meet the third characteristic change condition), it indicates that the interface not only has micro-gaps with concentrated shallow traps, but also impurities with dense deep traps. Therefore, it can be directly determined to be a highly risky suspected composite fusion defect or a high-risk interface defect.

[0112] In this embodiment, based on the logical combination of multi-dimensional quality characteristics and specific changing conditions, abstract electrical data can be accurately mapped into concrete types of insulation physical defects. This abandons the crude mode of relying on subjective human experience in traditional detection. By using rigorous logical conditional branches, the aliasing and depolarization response caused by different microscopic physical mechanisms (such as shallow trap groups caused by air gaps and deep trap groups caused by contamination) is decoupled, thereby improving the accuracy and identification capability of classifying and diagnosing extremely small interface defects of flexible joints.

[0113] In one embodiment, the quality inspection results for the submarine cable joint are determined based on quality characteristics, including:

[0114] By combining short-term relaxation features, long-term charge release, and charge release difference features, a fused quality feature vector for the submarine cable joint to be inspected is obtained. The fused quality feature vector is then matched with a pre-established defect calibration database to obtain the calibration matching result of the fused quality feature vector in the defect calibration database. Based on the calibration matching result, the quality inspection result of the submarine cable joint is determined.

[0115] The fusion quality feature vector can be a one-dimensional or multi-dimensional data sequence formed by splicing and combining multiple extracted insulation characterization parameters of different dimensions according to a specific data structure. It is mainly used to completely and structurally characterize the comprehensive charge release dynamics of the fusion interface of the submarine cable joint under test in a multi-dimensional feature space. The defect calibration database can be a pre-constructed reference mapping data set containing a large number of known insulation fusion state sample feature data and their corresponding physical real state labels. It is usually compiled based on prior polarization-depolarization test data of various typical defect samples and serves as a benchmark system for subsequent pattern recognition, similarity comparison, and state diagnosis. The calibration matching result can be a quantitative evaluation information obtained by optimizing the feature vector under test in the defect calibration database after distance calculation or classification mapping. It can typically cover the final mapping fusion quality level, the specific defect type, and the confidence level characterizing the reliability of the diagnostic conclusion.

[0116] Specifically, determining the quality inspection result of a submarine cable joint based on quality characteristics can be an alternative intelligent decision-making path parallel to feature threshold condition judgment. This mainly includes: fusing and combining features based on short-time relaxation features, long-time released charge, and charge release difference features to obtain a fused quality feature vector for the submarine cable joint to be inspected; subsequently, searching and matching the fused quality feature vector with a pre-established defect calibration database in a multi-dimensional space to obtain the calibration matching result corresponding to the fused quality feature vector in the defect calibration database; finally, determining the quality inspection result of the submarine cable joint based on the calibration matching result. For example, combining the actual testing and evaluation process of submarine cable joints, after extracting short-time relaxation features (e.g., time constant τ_s), long-time released charge (e.g., charge integral Q_L), and charge release difference features (e.g., dual-time-window power-law transition exponent Δn), these three can be directly constructed into a three-dimensional feature vector. Simultaneously, feature vectors are extracted from historical real physical samples (e.g., fully fused samples, air-gap defect samples, contamination defect samples, and composite defect samples) in advance, and a high-dimensional calibration database is established. During the matching process, the system can calculate the Euclidean distance and cosine similarity between the three-dimensional feature vector to be tested and the centers of known defect clusters in the database, or input the data into a pre-trained classification algorithm model, to obtain the most matching classification node for the vector in the database. Based on this calibration and matching result, the system can not only directly output the corresponding specific fusion quality level (e.g., Level I represents good interface fusion, Level II represents suspected air gap type fusion defect, Level III represents suspected contamination type fusion defect, and Level IV represents suspected composite fusion defect or high-risk interface defect), but also simultaneously output the confidence percentage of the judgment conclusion.

[0117] In this embodiment, by introducing a matching mechanism between feature vectors and calibration database, the quality evaluation mode of submarine cable joints can be transformed from a relatively rigid single-dimensional threshold comparison to a global pattern recognition in a multi-dimensional data space, providing a more comprehensive and objective insulation quality test for DC submarine cable flexible joints in factory batch handover tests or qualification evaluations.

[0118] In one embodiment, before acquiring the partitioned recovery current of the submarine cable joint to be tested in the depolarized state, the method further includes:

[0119] During the process of applying a DC polarization voltage between the cable conductor and the shielding layer of the submarine cable joint, the submarine cable joint is controlled to be at a preset test temperature; after the submarine cable joint is at the preset test temperature and the applied DC polarization voltage reaches the preset polarization time, the DC polarization voltage is cut off, triggering the submarine cable joint to enter the depolarization state, so as to obtain the partition recovery current of the submarine cable joint to be tested in the depolarization state.

[0120] Among them, the DC polarization voltage can be a high-voltage constant DC signal applied from the outside to stimulate the space charge injection and polarization effect of the internal insulating medium of the submarine cable joint before the insulation depolarization feature extraction. It is mainly used to provide sufficient initial energy and physical state basis for the subsequent release of trap charge.

[0121] The preset test temperature can be a specific controlled thermal environment temperature maintained by the flexible connector under test during the entire process of polarization and recovery current acquisition to simulate the actual operating conditions of the submarine cable.

[0122] The preset polarization time can be the time period during which the above-mentioned DC polarization voltage is continuously applied. Its setting is used to ensure that the energy level traps inside the insulation are fully captured by the injected charge.

[0123] For example, during the test preparation phase, such as Figure 3 As shown, the center conductor of the cable can be used as the high-voltage electrode, and the outer shielding layer, metal sheath, or insulating shielding layer can be used as the low-voltage electrode. Based on this wiring, a DC polarization voltage, preferably 1kV to 10kV, is applied between the two via an external high-voltage DC power supply. During this period, the flexible connector under test is controlled to be in a controlled thermal state of 40℃ to 80℃ by an external heating device to effectively improve the mobility of charge carriers inside the insulation. After maintaining this DC polarization voltage for a preset polarization time of 1800s to 7300s, sufficient charge injection, polarization, and trapping processes will occur at the molten interface of the flexible connector and its adjacent area. At this time, the external polarization power supply is quickly cut off and the depolarization test circuit is closed, thereby triggering the submarine cable connector to instantly switch from a strong electric field polarization state to a spontaneous charge release depolarization state, providing reliable pre-conditions for subsequent synchronous acquisition of weak multi-channel partitioned recovery currents.

[0124] In this embodiment, by introducing controlled thermal polarization pretreatment before obtaining the depolarization current, a stable and sufficient initial charge distribution field can be constructed for the molten interface of the submarine cable joint. This provides a sufficient signal source with a high signal-to-noise ratio for the subsequent depolarization stage, significantly amplifies the relaxation current response characteristics corresponding to the small interface defects, and improves the detection sensitivity and evaluation reliability of the entire partition protection recovery current evaluation method.

[0125] To enable those skilled in the art to better understand the above steps, the following example illustrates the embodiments of this application, but it should be understood that the embodiments of this application are not limited thereto.

[0126] like Figure 4 As shown, this application also provides the most detailed implementation method, including:

[0127] Step S401: Establish a zoned protection circuit. A measuring electrode is placed in the molten interface area of ​​the submarine cable joint to be tested. A first protective electrode and a second protective electrode are respectively placed on both sides of the measuring electrode. An insulating isolation zone is set between the measuring electrode and the first and second protective electrodes to maintain electrical isolation between adjacent electrodes. The width of the insulating isolation zone can be set according to factors such as the outer diameter of the flexible joint, the axial width of the electrode, the test voltage level, the surface leakage path length, and the input impedance of the acquisition circuit. In practical applications, the above-mentioned measuring electrode and the protective electrodes on both sides can be implemented by reserving shielding layer lead-out ends, outer shielding overlap areas, segmented grounding points of the metal sheath, temporary clamping ring electrodes, flexible conductive strips, or elastic conductive rings. Furthermore, the underlying multi-channel current acquisition circuit can adopt a shielded structure with separate measuring, protective, and grounding ends.

[0128] Step S402: Apply DC polarization. Apply a DC polarization voltage between the cable conductor and the shielding layer of the submarine cable joint, and control the submarine cable joint to be within a preset test temperature of 40°C to 80°C to improve the stability of the interface trap release characteristic. After the applied DC polarization voltage reaches the preset polarization time, control the switching module at the bottom layer to cut off the DC polarization voltage, triggering the submarine cable joint to enter the depolarization state.

[0129] Step S403: Synchronously acquire recovery current. Acquire the partitioned recovery current of the submarine cable joint in the depolarized state. The partitioned recovery current specifically includes the measurement electrode recovery current i_m(t), the first protection electrode recovery current i_g1(t), the second protection electrode recovery current i_g2(t), and the background current i_b(t) input to the channel.

[0130] Step S404: Perform compensation stripping. Obtain the first protection current compensation coefficient a_1 and the second protection current compensation coefficient a_2 determined by calibration, geometric model, finite element method, or short-time background test. Weight the recovery current of the first protection electrode according to the first protection current compensation coefficient to obtain the first protection compensation component, and weight the recovery current of the second protection electrode according to the second protection current compensation coefficient to obtain the second protection compensation component. Then, remove the first protection compensation component, the second protection compensation component, and the background current from the measured electrode recovery current to achieve the core calculation i_f(t)=i_m(t)-a_1*i_g1(t)-a_2*i_g2(t)-i_b(t), obtaining the effective recovery current i_f(t) corresponding to the molten interface region.

[0131] Step S405, Feature Extraction. Short-time relaxation features characterizing shallow traps are extracted from the effective recovery current, and long-time release charges characterizing the amount of trapped charge released from deep traps are extracted. Simultaneously, double log-linear fitting is performed on the effective recovery current within preset short and long time windows to obtain the difference between the decay exponents of the short and long time windows, thus determining the charge release difference characteristics.

[0132] Step S406, Fusion Quality Evaluation. Based on the above quality characteristics, a logical judgment is made: if the short-term relaxation characteristic and charge release difference characteristic meet the first characteristic change condition, and the long-term charge release does not meet the second characteristic change condition, the result is determined to be a Class II suspected air gap type fusion defect; if the long-term charge release meets the second characteristic change condition, and the charge release difference characteristic does not meet the first characteristic change condition, it is determined to be a Class III suspected contamination type fusion defect; if all three meet the third characteristic change condition, it is determined to be a Class IV composite / high-risk defect. Alternatively, in parallel, the above characteristics are combined into a fusion quality feature vector and matched with a defect labeling database to directly output the submarine cable joint inspection results, including quality levels such as Class I good fusion, specific defect types, or confidence levels.

[0133] This embodiment is applicable to factory acceptance tests, type tests, qualification tests, and engineering verification scenarios for DC submarine cable flexible joints. By constructing a zoned detection circuit using measuring electrodes and protective electrodes, testing can be carried out without cutting or stripping the main insulation of the flexible joint. By using a protective current compensation stripping method, the current in the non-target areas on both sides of the flexible joint, the surface leakage current, and the background current are subtracted from the recovery current of the measuring electrodes, making the obtained recovery current more reflective of the molten interface state. By changing the target of the recovery current detection from the entire cable insulation to the local area of ​​the molten interface of the flexible joint, it is beneficial to identify interface fusion defects such as air gaps, contamination, and weak bonding. By evaluating the interface fusion quality using short-time relaxation characteristics, long-time charge release, and dual-time-window power-law transition index, the ability to distinguish different types of fusion defects can be improved.

[0134] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. It should be noted that the method steps described in the embodiments of this application are not limited to a strict order. Without causing logical contradictions, the execution order of each step or stage can be adjusted or freely combined according to actual data processing needs. All non-contradictory combinations of solutions fall within the protection scope of this application.

[0135] Based on the same inventive concept, this application also provides a submarine cable joint quality inspection device for implementing the above-mentioned submarine cable joint quality inspection method. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more embodiments of the submarine cable joint quality inspection device provided below can be found in the limitations of the submarine cable joint quality inspection method described above, and will not be repeated here.

[0136] In one exemplary embodiment, such as Figure 5 As shown, a submarine cable joint quality inspection device is provided, comprising: a recovery current acquisition module 510, an effective current acquisition module 520, and a test result determination module 530, wherein:

[0137] The recovery current acquisition module 510 is used to acquire the partition recovery current of the submarine cable joint in the depolarized state; wherein, the partition recovery current includes the measurement electrode recovery current, the first protection electrode recovery current, the second protection electrode recovery current and the background current;

[0138] The effective current acquisition module 520 is used to perform compensation stripping processing on the recovery current of the measuring electrode based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current, so as to obtain the effective recovery current corresponding to the molten interface region.

[0139] The detection result determination module 530 is used to extract quality features from the effective recovery current and determine the quality detection result of the submarine cable joint based on the quality features.

[0140] In one embodiment, the recovery current acquisition module 510 is further configured to:

[0141] During the process of applying a DC polarization voltage between the cable conductor and the shielding layer of the submarine cable joint, the submarine cable joint is controlled to be at a preset test temperature; after the submarine cable joint is at the preset test temperature and the DC polarization voltage is applied for a preset polarization time, the DC polarization voltage is cut off, triggering the submarine cable joint to enter the depolarization state, so as to obtain the partition recovery current of the submarine cable joint to be tested in the depolarization state.

[0142] In one embodiment, the effective current acquisition module 520 is further configured to:

[0143] Obtain the first protection current compensation coefficient corresponding to the first protection electrode and the second protection current compensation coefficient corresponding to the second protection electrode; perform weighted processing on the recovery current of the first protection electrode according to the first protection current compensation coefficient to obtain the first protection compensation component, and perform weighted processing on the recovery current of the second protection electrode according to the second protection current compensation coefficient to obtain the second protection compensation component; remove the first protection compensation component, the second protection compensation component and the background current from the recovery current of the measuring electrode to obtain the effective recovery current corresponding to the molten interface region.

[0144] In one embodiment, the detection result determination module 530 is further configured to:

[0145] From the effective recovery current, the short-time relaxation feature used to characterize the charge release time of the shallow traps in the molten interface region, and the long-time release charge used to characterize the amount of charge released from the deep traps in the molten interface region are extracted; the effective recovery current is subjected to double logarithmic linear fitting within a preset short time window to obtain the short-time window decay index; the effective recovery current is subjected to double logarithmic linear fitting within a preset long time window to obtain the long-time window decay index; the difference between the short-time window decay index and the long-time window decay index is obtained, and the charge release difference feature is determined based on the difference.

[0146] In one embodiment, the detection result determination module 530 is further configured to:

[0147] If the short-term relaxation feature and the charge release difference feature satisfy the first feature change condition, and the long-term charge release does not satisfy the second feature change condition, then the quality inspection result of the submarine cable joint is determined to be an air gap type fusion defect; or, if the long-term charge release satisfies the second feature change condition, and the charge release difference feature does not satisfy the first feature change condition, then the quality inspection result of the submarine cable joint is determined to be a contamination type fusion defect; or, if the short-term relaxation feature, the long-term charge release, and the charge release difference feature all satisfy the third feature change condition, then the quality inspection result of the submarine cable joint is determined to be a composite type fusion defect.

[0148] In one embodiment, the detection result determination module 530 is further configured to:

[0149] Based on the combination of the short-term relaxation features, the long-term charge release, and the charge release difference features, a fused quality feature vector corresponding to the submarine cable joint to be inspected is obtained; the fused quality feature vector is matched with a pre-established defect calibration database to obtain the calibration matching result corresponding to the fused quality feature vector in the defect calibration database; based on the calibration matching result, the quality inspection result of the submarine cable joint is determined.

[0150] Each module in the aforementioned submarine cable joint quality inspection device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0151] In one exemplary embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 6 As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a method for inspecting the quality of submarine cable joints.

[0152] Those skilled in the art will understand that Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0153] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0154] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0155] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0156] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0157] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0158] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0159] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for quality inspection of submarine cable joints, characterized in that, A measuring electrode is provided in the molten interface region of the submarine cable joint to be inspected, and a first protective electrode and a second protective electrode are respectively provided on both sides of the measuring electrode. The method includes: The partition recovery current of the submarine cable joint in the depolarized state is obtained; wherein, the partition recovery current includes the recovery current of the measuring electrode, the recovery current of the first protection electrode, the recovery current of the second protection electrode, and the background current; The recovery current of the measuring electrode is compensated and stripped based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current to obtain the effective recovery current corresponding to the molten interface region. The process of compensating and stripping the recovery current of the measuring electrode based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current to obtain the effective recovery current corresponding to the molten interface region includes: obtaining a first protective current compensation coefficient corresponding to the first protective electrode and a second protective current compensation coefficient corresponding to the second protective electrode; weighting the recovery current of the first protective electrode according to the first protective current compensation coefficient to obtain a first protective compensation component, and weighting the recovery current of the second protective electrode according to the second protective current compensation coefficient to obtain a second protective compensation component; and removing the first protective compensation component, the second protective compensation component, and the background current from the recovery current of the measuring electrode to obtain the effective recovery current. Quality features are extracted from the effective recovery current, and the quality inspection results of the submarine cable joint are determined based on the quality features.

2. The method according to claim 1, characterized in that, The quality characteristics include at least two of the following: short-time relaxation characteristics, long-time charge release characteristics, and charge release difference characteristics; The extraction of quality features from the effective recovery current includes at least two of the following processes: From the effective recovery current, extract the short-time relaxation feature used to characterize the charge release time of the shallow traps in the molten interface region; From the effective recovery current, extract the long-term released charge used to characterize the amount of deep trapped charge released in the molten interface region; Based on the decay trend of the effective recovery current within a preset short-time window and a long-time window, the charge release difference characteristics are determined.

3. The method according to claim 2, characterized in that, The decay trend is characterized by a short-time window decay index and a long-time window decay index. The determination of the charge release difference characteristics based on the decay trend of the effective recovery current within a preset short-time window and a long-time window includes: The effective recovery current is subjected to double log-linear fitting within the short time window to obtain the short time window decay index; The effective recovery current is subjected to double log-linear fitting within the long time window to obtain the long time window decay index; The difference between the short-time window decay index and the long-time window decay index is obtained, and the charge release difference characteristics are determined based on the difference.

4. The method according to claim 2, characterized in that, The process of determining the quality inspection result of the submarine cable joint based on the quality characteristics includes: If the short-term relaxation characteristic and the charge release difference characteristic satisfy the first characteristic change condition, and the long-term charge release does not satisfy the second characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be an air gap type fusion defect; or, If the long-term released charge satisfies the second characteristic change condition, and the charge release difference characteristic does not satisfy the first characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be a contamination-type fusion defect; or, If the short-term relaxation characteristic, the long-term charge release characteristic, and the charge release difference characteristic all satisfy the third characteristic change condition, then the quality inspection result of the submarine cable joint is determined to be a composite fusion defect.

5. The method according to claim 2, characterized in that, The process of determining the quality inspection result of the submarine cable joint based on the quality characteristics includes: The fused quality feature vector corresponding to the submarine cable joint to be detected is obtained by combining the short-term relaxation feature, the long-term charge release feature, and the charge release difference feature. The fused quality feature vector is matched with a pre-established defect calibration database to obtain the calibration matching result of the fused quality feature vector in the defect calibration database; Based on the calibration and matching results, the quality inspection results of the submarine cable joint are determined.

6. The method according to any one of claims 1 to 5, characterized in that, Before obtaining the partitioned recovery current of the submarine cable joint to be tested in the depolarized state, the method further includes: During the process of applying a DC polarization voltage between the cable conductor and the shielding layer of the submarine cable joint, the submarine cable joint is controlled to be at a preset test temperature. When the submarine cable joint is at the preset test temperature and the DC polarization voltage is applied for a preset polarization time, the DC polarization voltage is cut off, triggering the submarine cable joint to enter the depolarization state, so as to obtain the partition recovery current of the submarine cable joint to be tested in the depolarization state.

7. A device for inspecting the quality of submarine cable joints, characterized in that, A measuring electrode is provided in the molten interface region of the submarine cable joint to be inspected, and a first protective electrode and a second protective electrode are respectively provided on both sides of the measuring electrode. The device includes: The recovery current acquisition module is used to acquire the partitioned recovery current of the submarine cable joint in the depolarized state; wherein, the partitioned recovery current includes the measurement electrode recovery current, the first protection electrode recovery current, the second protection electrode recovery current, and the background current; An effective current acquisition module is used to perform compensation and stripping processing on the recovery current of the measuring electrode based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current to obtain the effective recovery current corresponding to the molten interface region. The step of performing compensation and stripping processing on the recovery current of the measuring electrode based on the recovery current of the first protective electrode, the recovery current of the second protective electrode, and the background current to obtain the effective recovery current corresponding to the molten interface region includes: acquiring a first protection current compensation coefficient corresponding to the first protective electrode and a second protection current compensation coefficient corresponding to the second protective electrode; weighting the recovery current of the first protective electrode based on the first protection current compensation coefficient to obtain a first protection compensation component, and weighting the recovery current of the second protective electrode based on the second protection current compensation coefficient to obtain a second protection compensation component; and removing the first protection compensation component, the second protection compensation component, and the background current from the recovery current of the measuring electrode to obtain the effective recovery current. The detection result determination module is used to extract quality features from the effective recovery current and determine the quality detection result of the submarine cable joint based on the quality features.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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