A monitoring method for switch cabinet operation health management

Abstract

The application relates to the technical field of fault prediction and health management, and discloses a monitoring method for switch cabinet operation health management, which comprises the following steps: synchronously collecting load current data and contact resistance data of a conductive contact unit; based on an electric power mechanism, determining a square term of the load current data as an equivalent rolling force, and converting a dynamic fluctuation amount of the contact resistance data into an equivalent reduction amount representing interface displacement change; extracting a characteristic component with a frequency of 100 Hz in the equivalent rolling force and a corresponding coherent component, and inversely determining an equivalent stiffness index of the conductive contact unit according to the characteristic component and the coherent component; performing a virtual unloading procedure by identifying a low-load window with a load current lower than 5% of a rated value, and correcting a mechanical benchmark by using a residual deformation amount, so that the application realizes accurate decoupling of mechanical fatigue and interface oxidation, advances the monitoring dimension from temperature rise feedback to a stress evolution stage, and effectively solves a benchmark drift problem caused by long-period service.

Description

Technical Field

[0001] This invention relates to a monitoring method for the health management of switchgear operation, belonging to the field of fault prediction and health management technology. Background Technology

[0002] Currently, in the operation and maintenance of power distribution systems, the contact status of the moving and stationary contacts of switchgear is a key factor in ensuring the safe operation of the system. In the current technical field, temperature rise monitoring or partial discharge detection are usually used as the main methods to assess the health status of the contacts. Temperature rise is the end effect after the deterioration of contact performance, and it shows a significant lag compared to the mechanical fatigue of the contact spring. In actual operating environments, when the temperature characteristics are obvious, the contact interface has often already suffered physical damage. Due to the high-voltage insulation requirements and compact space in the cabinet, directly placing force-sensitive sensors at the contact points faces technical obstacles such as high engineering implementation difficulty and reduced system stability.

[0003] Besides the implementation difficulties at the hardware level, existing monitoring logic is often limited in its dimensionality to the simulation and deduction of overall thermal effects. For example, Chinese invention patent CN115856486B discloses a method and system for thermal fault diagnosis and early warning of intelligent switchgear. It predicts temperature rise by establishing a mapping relationship between ambient temperature and contact heat. This type of solution essentially still uses heat accumulation as the core criterion. Although the established mapping model can improve the accuracy of temperature rise early warning, it cannot reach the physical root cause of failure, that is, it cannot directly perceive the stress evolution process of the contact support structure. When the thermal mapping model captures abnormal fluctuations, the contact support... The components have often already undergone irreversible fatigue deformation, and such models cannot physically separate the two fundamentally different failure modes of interface oxide layer thickening and mechanical structure relaxation, making subsequent predictive maintenance lack accurate mechanical criteria. Existing monitoring logic mainly relies on the analysis of static resistance drift, lacking in-depth exploration of the microscopic deformation law of metal contact interface under periodic electrodynamic disturbances generated by alternating current. Existing solutions cannot establish a physical mapping relationship between electrical signal fluctuations and interface mechanical stiffness attenuation without compromising equipment sealing and without increasing sensor load, resulting in a lack of reliable criteria for predictive maintenance for mechanical fatigue.

[0004] Therefore, the technical problem to be solved by this invention is how to provide a monitoring method for the health management of switchgear operation, which realizes real-time reconstruction of the mechanical state of the contact interface through the electrodynamic characteristics excited by the loop current. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A monitoring method for the operational health management of switchgear, comprising the following steps:

[0006] Step S1: Simultaneously acquire the load current data and contact resistance data of the conductive contact unit. Utilize the periodic electric repulsion characteristics generated by alternating current to determine the square term of the load current data as the equivalent rolling force acting on the contact interface of the conductive contact unit. Step S2: Utilize the micro-deformation response characteristics of the contact interface to convert the dynamic fluctuation of the contact resistance data into an equivalent reduction that characterizes the micro-displacement change of the contact interface. Step S3: Perform frequency domain decomposition on the equivalent rolling force and the equivalent reduction, extract the characteristic component with a frequency of 100Hz in the equivalent rolling force, and extract the coherent component with the same phase as the characteristic component from the equivalent reduction. Use the same frequency coherence to filter out the background interference signal in the equivalent reduction. Step S4: Calculate the amplitude ratio of the characteristic component and the coherent component, and determine the equivalent stiffness index of the conductive contact unit under the current working condition based on the amplitude ratio inversion. Step S5: Monitor load current data. When it is identified that the load current data is continuously below 5% of the rated current value during a low-load period, obtain the residual deformation of the conductive contact unit in the zero electrodynamic state, and use the residual deformation to correct the mechanical reference of the equivalent stiffness index. Step S6: Compare the deviation between the corrected equivalent stiffness index and the preset initial nominal stiffness. When the deviation exceeds the preset change threshold, output the evaluation result characterizing the mechanical fatigue state or interface oxidation degree of the conductive contact unit.

[0007] Preferably, when performing step S1, the acquisition frequency of both load current data and contact resistance data is not less than 10kHz; at the same time, the current acquisition channel and resistance acquisition channel are phase aligned using a synchronous clock so that the equivalent rolling force and the equivalent reduction form a causal response relationship in the time domain.

[0008] Preferably, in step S2, when converting the dynamic fluctuation of the contact resistance data into an equivalent reduction, a roughness correction factor characterizing the distribution of conductive spots at the contact interface is introduced to linearize the nonlinear fluctuation of the contact resistance data into microscopic deformation displacement.

[0009] Preferably, when extracting coherent components in step S3, a window function is used to truncate the equivalent compression, and the cross-correlation coefficient between the equivalent compression and the standard 100Hz sine signal is calculated. Only signal components with cross-correlation coefficients exceeding a preset correlation threshold are retained as effective response signals for calculating the equivalent stiffness index.

[0010] Preferably, in step S4, when determining the equivalent stiffness index through inversion, the phase deviation between the feature component and the coherent component is extracted simultaneously, and the phase deviation is converted into the mechanical damping parameter of the conductive contact unit. A health status discrimination matrix is ​​constructed by combining the equivalent stiffness index and the mechanical damping parameter into a two-dimensional vector.

[0011] Preferably, during dynamic correction in step S5, the residual deformation displacement is extracted by recording the trajectory evolution of the equivalent reduction during the low-load period, and the reference stiffness value is updated using the following formula: ,in, The updated reference stiffness value, The instantaneous equivalent rolling force at the moment of activation during low-load periods. This refers to the instantaneous equivalent reduction at the moment of startup during low-load periods. This represents the residual deformation displacement.

[0012] Preferably, when outputting the evaluation results in step S6, if the equivalent stiffness index decreases monotonically and the mechanical damping parameter remains stable, it is determined that the supporting component of the conductive contact unit has undergone stress relaxation; if the equivalent stiffness index remains stable and the mechanical damping parameter increases monotonically, it is determined that the oxide layer has thickened at the contact interface.

[0013] Preferably, after outputting the evaluation results, the following action is performed: when the equivalent stiffness index falls below 70% of the initial nominal stiffness, a warning signal containing the risk of mechanical support failure is generated.

[0014] Preferably, before performing step S6, the equivalent stiffness index is corrected for thermal stress using ambient temperature, with the correction range covering -20°C. Up to 60 The elastic modulus of the peeling material fluctuates with seasonal temperature differences.

[0015] Preferably, by establishing a cloud database to compare the equivalent stiffness indices of multiple switchgear units of the same model, the early health risk points of individual equipment are identified by utilizing the statistical characteristics of group distribution, and the remaining reliable life of conductive contact units is predicted based on the stiffness decay trajectory of individual equipment during long-term service.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. In the health management of switchgear operation, non-invasive quantitative monitoring of mechanical status in a closed operating environment is achieved: By collecting instantaneous current signals of the circuit, a virtual rolling force model is constructed using the physical relationship between electrodynamic force and the square of current. Combined with the displacement mapping caused by contact resistance fluctuations, traditional electrical parameter monitoring is transformed into mechanical state perception. Using the periodic electric repulsive force generated by alternating current as an endogenous excitation source, without the need to install pressure sensors, the equivalent stiffness of the contact system is deconstructed in real time by analyzing the dynamic mapping relationship between force and displacement. This transformation from thermal perception to mechanical essence perception solves the industry problem of difficulty in quantitatively obtaining the contact pressure attenuation trajectory in switchgear under closed operating conditions, and advances the monitoring of mechanical fatigue from the end temperature rise feedback to the stress evolution stage.

[0017] 2. Accurate identification of failure modes through multi-dimensional signal decoupling: This invention extracts the phase deviation between virtual rolling force and virtual deformation displacement during the periodic evolution process and maps it to the mechanical damping parameters of the contact interface. By establishing a two-dimensional discrimination matrix of stiffness index and damping parameter, the system can distinguish between structural instability caused by spring fatigue and interface performance degradation caused by contact oxidation. When the stiffness index remains stable while the damping parameter increases monotonically, it is determined to be a thickening of the surface oxide layer; when both deteriorate simultaneously, it is determined to be a mechanical structural failure. This deep separation of physical and chemical failure characteristics avoids the problem of misjudging the fault source due to the increase in contact impedance in traditional monitoring, and provides reliable data support for accurate operation and maintenance decisions.

[0018] 3. Establish a dynamic physical benchmark system with self-calibration capability: In response to structural creep and stress relaxation during the long-term service of power equipment, this invention identifies the no-load window when the load drops below 5%, triggers a virtual unloading procedure and records the residual deformation trajectory. The extracted residual displacement deviation is used to update the benchmark stiffness field in real time, enabling the health assessment model to adapt to the physical scale drift of the equipment over a service period of several years. This mechanism transforms the load fluctuation, which was originally a disturbance, into a benchmark correction opportunity, ensuring that the stiffness deviation calculation is always based on the current physical state and eliminating false warnings caused by the long-term inelastic evolution of materials. Attached Figure Description

[0019] Figure 1 This is a flowchart of the monitoring method for electrodynamic mechanism and stiffness inversion of the present invention; Figure 2 This is a block diagram illustrating the principle of the monitoring system integrating synchronous data acquisition and virtual mechanical model of this invention. Detailed Implementation

[0020] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further explanation of the monitoring method for the operational health management of switchgear claimed in this invention. The following embodiments are intended to illustrate the invention and are not intended to limit the scope of protection of the invention.

[0021] This invention provides a monitoring method for the operational health management of switchgear, including synchronous signal acquisition, virtual mechanical model construction, frequency domain feature decoupling, dynamic correction of mechanical benchmarks, and output of health assessment results. The system utilizes the electrodynamic characteristics excited by the loop current to quantitatively monitor the mechanical state of the contact interface. It uses the periodic electrodynamic repulsion force generated by alternating current as a physical excitation source to establish a deterministic logic between electrical signal fluctuations and interface mechanical stiffness attenuation. Addressing the difficulty in directly obtaining pressure attenuation characteristics of the switchgear's moving and stationary contacts in a closed operating environment, the system acquires instantaneous loop current signals and constructs a virtual rolling force model. During processing, the system synchronously acquires load current data and contact resistance data of the conductive contact unit using current and resistance acquisition channels. To ensure a causal response relationship in the time domain, the system uses a synchronous clock to phase-align the two acquisition channels and sets the sampling frequency to no less than 10kHz. Based on the proportional relationship between the electrodynamic force generated by the current and the square of the current, the system determines the square term of the load current data as the equivalent rolling force acting on the contact interface of the conductive contact unit. Its calculation formula is expressed as: ,in, Equivalent rolling force, unit: N; The structural constant is pre-calibrated based on the contact geometry. The calibration process is as follows: During the commissioning phase, a power frequency AC current from 100A to 1000A is injected into the circuit, with a step increment of 50A. Simultaneously, the electrodynamic force on the contact is measured using a high-precision pressure sensor. By calculating the ratio of the measured electrodynamic force value to the square value of the current, it is determined that under this batch of hardware, the sum of the squares of the current for every 10000A² corresponds to an equivalent rolling force of 1.28N, i.e., the structural constant is set to 0.128N / A². This is an instantaneous current signal, measured in amperes (A). For example, in a switchgear with a rated current of 1250A, when the real-time effective value of the instantaneous current is 600A, according to the preset structural constants... Calculate the periodic electrodynamic repulsion force on the contact interface and translate it into an equivalent rolling force.

[0022] The conductive contact unit was installed on a calibration bench equipped with a displacement sensor and a hydraulic loading device. A stepped pressurization was applied within the range of 500N to 2500N, and a 100A AC power frequency was injected simultaneously. Data points corresponding to the contact resistance fluctuation and the micro-displacement of the contact interface under different pressure gradients were recorded. The structural constants were determined by fitting the square term of the current with the measured electrodynamic force using the least squares method. A displacement conversion coefficient matrix is ​​established based on the evolution curve of contact resistance with pressure, so that the resistance fluctuation during operation can be converted into an equivalent pressure reduction based on the displacement conversion coefficient matrix. Because the contact interface undergoes microscopic deformation response when subjected to electrodynamic disturbances, this scheme converts the dynamic fluctuation of contact resistance data into an equivalent reduction that characterizes the interface displacement change. In the contact system, the change in contact resistance... There is a physical correspondence between the contact pressure fluctuation and the impedance calculation. To eliminate nonlinear interference, this scheme introduces a roughness correction factor that characterizes the conductive spot distribution at the contact interface. An impedance displacement mapping vector, calibrated based on a pressure gradient from 500N to 2000N, is pre-set within the processor. By real-time retrieval of the absolute value of the current contact resistance fluctuation, it is scaled according to a linear relationship of 0.15μm displacement change for every 1.0µΩ resistance fluctuation. When an increase in resistance is detected, the corresponding displacement increment is simultaneously accumulated, linearizing the contact resistance data fluctuation into microscopic deformation displacement. This step transforms the mechanical displacement, which is difficult to measure directly, into observable electrical signal characteristics. Before performing frequency domain decomposition, the system preprocesses the equivalent compression to suppress spectral leakage. The processor selects a Hamming window function with a length of 1024 sampling points as the truncation operator and performs point-by-point multiplication of the time-domain discrete sequence with the Hamming window coefficient vector. The processor sets the overlap rate of adjacent sampling windows to 50% to compensate for signal gain loss at the window edges. After completing the windowing process, the processor extracts the coherent component amplitude corresponding to the 100Hz physical excitation source through integration. This preprocessing procedure based on deterministic coefficient vectors ensures the computational convergence accuracy of micro-deformation feature extraction under a 20dB signal-to-noise ratio.

[0023] Considering the presence of power frequency harmonics and background noise in the operating environment, this solution employs a coherent frequency extraction method to improve the signal-to-noise ratio. The system performs frequency domain decomposition processing on the equivalent rolling force and equivalent reduction, and uses a spectrum analysis method based on Fast Fourier Transform to extract the 100Hz characteristic component from the equivalent rolling force. The system extracts the coherent component with the same phase as the characteristic component from the equivalent reduction. During processing, the system uses a window function to truncate the equivalent reduction and calculates its cross-correlation coefficient with a standard 100Hz sine wave. When the cross-correlation coefficient exceeds a preset correlation threshold of 0.8, the system retains this signal component as a valid response signal. By using the amplitude ratio of the characteristic component and the coherent component, the system determines the equivalent stiffness index of the conductive contact unit under the current operating conditions. The specific calculation formula is as follows: ,in, This is the equivalent stiffness index, with units of N / m; The characteristic component amplitude of the equivalent rolling force, in N; The equivalent reduction is expressed as the amplitude of the coherent component in meters (m). The processor uses a 10kHz synchronous trigger pulse to synchronously sample the load current and contact resistance, selecting a length... Hamming window functions at sampling points are used to window the sampling sequence to suppress spectral leakage. The amplitudes of the characteristic and coherent components at the 100Hz physical excitation frequency are extracted using Fast Fourier Transform, and the phase deviation between the characteristic and coherent components is calculated. Based on the second-order forced vibration dynamics model under electrodynamic excitation, the phase deviation is... Convert to mechanical damping parameters The processor performs the conversion by consulting a phase damping lookup table stored in memory. This table defines a mapped mechanical damping coefficient of 0.02 when the phase lag of the equivalent reduction with the equivalent rolling force is 5.0° at a 100Hz excitation frequency; and a mapped mechanical damping coefficient of 0.05 when the phase angle increases to 10.0°. For phase angles in the middle, a precise damping value is calculated using linear interpolation, along with the system's natural frequency. The instantaneous response hysteresis under electrodynamic excitation was obtained through a pre-commissioning impact response test and quantified into a damping physical index characterizing the degree of oxidation at the contact interface.

[0024] To address the reference drift issue caused by long-term service of power equipment, this solution introduces a dynamic reference stiffness correction method based on virtual unloading trajectory. During the health assessment process, the system monitors load current data in real time. When it detects that the load current data is continuously below 5% of the rated current for more than 10 seconds, a virtual unloading procedure is triggered. The system records the trajectory evolution of the equivalent reduction during this low-load period and extracts the residual deformation displacement after the electrodynamic force returns to zero. This displacement reflects the physical displacement deviation of the supporting components due to stress relaxation or material creep. The system updates the reference stiffness value using the following formula. : ,in, The updated reference stiffness value is expressed in N / m. The instantaneous equivalent rolling force at the moment of start-up during low-load periods, expressed in N; The instantaneous equivalent reduction at the moment of activation during low-load periods, expressed in meters (m). Residual deformation displacement, in meters, is used to identify load currents that are consistently below 5% of the rated current for more than 10 seconds. During the low-load window, initiate the reference repair procedure and record the equivalent reduction in voltage during the removal of the electrodynamic excitation. Time evolution trajectory, monitoring equivalent compression amount Real-time rate of change, when the absolute value of the rate of change is less than 0.01. Extract the current displacement value as the residual deformation. This residual displacement represents the irreversible displacement of the support component due to material stress relaxation or creep. Substituting it into the reference stiffness update formula... The mechanical base is corrected to ensure that the stiffness deviation calculation results under full load operation conditions exclude drift caused by environmental and time factors. By identifying the amount of irreversible plastic deformation and correcting the mechanical benchmark in real time, it ensures that the stiffness deviation calculation during subsequent full load operation is based on the current physical base condition, thus eliminating false alarms caused by long-term aging.

[0025] To identify mechanical fatigue and interface oxidation, the system extracts the phase deviation between the feature components and the coherent components. This phase deviation is mapped to the mechanical damping parameters of the conductive contact unit. The system constructs a health status discrimination matrix by combining the equivalent stiffness index and the mechanical damping parameters into a two-dimensional vector. When constructing the health status discrimination matrix, the processor executes an envelope-based discrimination procedure. The system then uses the equivalent stiffness index... The normalized attenuation warning threshold is set to 0.30, and the mechanical damping parameter is... The degradation growth threshold is set at 50%, when the processor detects the equivalent stiffness index The attenuation relative to the nominal value exceeds the normalized attenuation warning threshold and the mechanical damping parameter When the time-series fluctuation variance remains below 0.05, the system determines the dominant failure mode as fatigue of the supporting components and outputs the corresponding maintenance work order; if the equivalent stiffness index The fluctuation range is less than 10% and the mechanical damping parameter When the real-time measured value crosses the degradation growth threshold, the system determines that the dominant failure mode is contact interface oxidation. This determination logic, based on multi-dimensional vector feature projection, provides a deterministic assessment result controlled by the inflection point of physical performance. Finally, the system modifies the equivalent stiffness index. The system compares the deviation from the preset initial nominal stiffness. When the deviation exceeds the 30% change threshold, the system outputs the evaluation result and generates an early warning signal. This method relies on algorithm-driven operation and reuses existing current sampling channels, making it highly feasible for engineering implementation. Before execution, the system uses ambient temperature to correct the equivalent stiffness index, with the correction range covering -20℃ to 60℃, to eliminate fluctuations in the material's elastic modulus caused by seasonal temperature differences. In addition, the system establishes a cloud database to compare the equivalent stiffness index of multiple switchgear units of the same model, uses the statistical characteristics of group distribution to identify the health risks of individual equipment, and predicts the remaining reliable life of conductive contact units.

[0026] Example 1: In the monitoring scenario of a 10kV switchgear operating under high current conditions in the metallurgical industry, the conductive contact unit is subjected to the coupling effect of alternating electrodynamic excitation and thermal stress during long-term service. This causes the support springs of the contact system to exhibit an unobservable decrease in stiffness due to fatigue. Due to external vibration interference from heavy machinery on site, the monitoring method based on contact temperature changes cannot provide a physically based health warning signal in the early stage of interface pressure decay due to the hysteresis effect of thermal equilibrium establishment and the noise masking of environmental fluctuations. When the periodic electrodynamic pulses generated by the circuit load current act on the contact interface, the system synchronously collects the load current data and determines the equivalent rolling force based on its square term. Simultaneously, the collected contact resistance data is mapped to an equivalent reduction amount reflecting the interface deformation displacement. By performing frequency domain coherence extraction based on Fast Fourier Transform on the two signals, a 100Hz characteristic component reflecting the interface mechanical response characteristics is obtained after effectively removing background mechanical vibration noise. The equivalent stiffness index of the conductive contact unit is determined in real time by using the amplitude ratio of this component. Equivalent stiffness index The calculation formula is as follows: ,in, This is the equivalent stiffness index, with units of N / m; Equivalent rolling force The amplitude of the characteristic component at a frequency of 100Hz, in N; The equivalent reduction is expressed as the amplitude of the coherent component at the corresponding frequency, in meters (m).

[0027] To address the challenge of reference drift caused by stress relaxation after years of service in contact systems, the system extracts residual deformation displacement reflecting plastic deformation by recording the equivalent compression trajectory during the electrodynamic excitation removal process during low-load periods when the effective value of the load current drops below 5% of the rated current. This displacement reflects the physical displacement deviation of the supporting components due to stress relaxation or material creep. The system updates the reference stiffness value using the following formula. : ,in, The updated reference stiffness value is expressed in N / m. The instantaneous equivalent rolling force at the moment of start-up during low-load periods, expressed in N; The instantaneous equivalent reduction at the moment of activation during low-load periods, expressed in meters (m). The residual deformation displacement is expressed in meters (m). By identifying irreversible plastic deformation and correcting the mechanical reference in real time, it ensures that the stiffness deviation calculation during subsequent full-load operation is based on the current physical base condition, eliminating false alarms caused by long-term aging. This is based on the corrected equivalent stiffness index. The system identifies the equivalent stiffness index using the discrimination matrix formed by the interface mechanical damping parameters. The monotonically decreasing trend while the mechanical damping parameter remains constant proves that the current equipment is in the mechanical fatigue stage caused by the deterioration of spring support performance, rather than contact deterioration caused by surface oxidation. Before the contact resistance undergoes a substantial jump and the temperature rises abnormally, the system outputs a maintenance warning signal through the control terminal. This monitoring method changes the logic of simply relying on the feedback of ambient temperature rise, and transforms the judgment basis into a direct characterization of the internal stress evolution state of the contact system. This transforms the originally difficult-to-quantify mechanical fatigue process into a deterministic monitoring process controlled by the parameters of the mechanical model.

[0028] Example 2: In a physical test platform simulating the operating conditions of a 10kV switchgear, the test data comes from the measured waveforms acquired by the platform, including a high-voltage vacuum circuit breaker with a rated current of 1250A and its associated conductive contact unit. The current transformer on the platform has a sampling accuracy of 0.2 class, and the contact resistance measurement circuit has a resolution of 0.1μΩ. To simulate the electromagnetic environment of a real substation, Gaussian white noise with a signal-to-noise ratio of 20dB is superimposed on the test signal source, and a 50Hz power frequency interference harmonic is introduced. The selection of the system sampling frequency depends on the signal spectrum bandwidth and processing... The technical trade-offs regarding the computational load of the device are as follows: Since the electrodynamic repulsion force generated by the loop current is concentrated at 100Hz and its harmonics, the sampling frequency is set at 10kHz to capture micro-deformation characteristics and avoid signal aliasing. The threshold value for the cross-correlation coefficient depends on the trade-off between environmental noise levels and feature recognition accuracy. Under this experimental condition, the threshold value is set to 0.8. The prototype of this invention operates under a steady-state load current of 800.5A, and the measured initial contact resistance is 45.2μΩ. The system uses the periodic electrodynamic repulsion force experienced by the conductive contact unit as excitation to calculate the equivalent rolling force. Characteristic component amplitude The amplitude of the coherent component of the equivalent reduction was 152.3 N, extracted simultaneously. The effective stiffness index of the conductive contact unit is determined by calculating the ratio between the two values, which is 2.14 μm. It is 71.17 N / μm; specifically, the equivalent stiffness index is... The calculation formula is as follows: ,in, This is the equivalent stiffness index, with units of N / m; Equivalent rolling force The amplitude of the characteristic component at a frequency of 100Hz, in N; The equivalent reduction is expressed as the amplitude of the coherent component at the corresponding frequency, in meters (m).

[0029] When the frequency domain coherence extraction step is removed and stiffness is calculated using only the time domain signal, the calculated equivalent stiffness index fluctuates between 60.5 N / μm and 85.2 N / μm due to background vibration interference, failing to form a stable health criterion. However, in the sample of this invention, through phase alignment processing of the characteristic components and coherent components, the equivalent stiffness index is improved even under conditions with superimposed Gaussian white noise. The standard deviation is 0.42 N / μm, reflecting the synergistic effect of the current square term and the resistance fluctuation term in the frequency domain on the suppression of incoherent noise. The experiment simulated the fault gradient caused by the failure of the support spring, resulting in a 30% drop in contact pressure. The results show that the equivalent stiffness index output by the sample group of this invention is [missing information]. The temperature dropped to 49.82 N / μm, with a deviation of 30.01%, triggering a warning signal. At this time, the temperature rise at the contact interface increased by 1.2℃. When the load current was reduced to 2% of the rated value, i.e., 25.1A, the electrodynamic amplitude decreased to 0.05N, and the cross-correlation coefficient calculated by the system dropped to 0.65, which was lower than the preset threshold of 0.8. The system recognized this and entered the virtual unloading procedure, extracting a residual deformation displacement of 0.15μm. Reference stiffness value The update formula is as follows: ,in, The updated reference stiffness value is expressed in N / m. The instantaneous equivalent rolling force at the moment of start-up during low-load periods, expressed in N; The instantaneous equivalent reduction at the moment of activation during low-load periods, expressed in meters (m). This represents the residual deformation displacement, in meters (m).

[0030] Example 3: This example combines Figures 1 to 2 This describes a monitoring method for the operational health management of a switchgear, such as... Figure 1 As shown, synchronous acquisition is initiated to acquire load current data and contact resistance data in parallel. On the one hand, the equivalent rolling force is determined based on the square term of the load current. On the other hand, the dynamic fluctuation of contact resistance is converted to convert the equivalent reduction. The above data is processed by frequency domain decomposition to extract the 100Hz characteristic component and coherent component. Based on the amplitude ratio, the inverse equivalent stiffness index is calculated. On this basis, it is determined whether the low load window is identified, that is, the load current is less than 5% of the rated value. If it is determined to be yes, the residual deformation is obtained to correct the mechanical benchmark and proceed to the next step. If it is determined to be no, it directly enters the deviation comparison stage and compares with the initial nominal stiffness. Finally, the evaluation result including mechanical fatigue or interface oxidation is output.

[0031] like Figure 2As shown, the system includes a switch cabinet and a signal acquisition system. The conductive contact unit in the switch cabinet includes a moving and stationary contact interface and a supporting spring. Its physical signals are connected to the signal acquisition system. The acquisition system is equipped with a current acquisition channel and a resistance acquisition channel, and phase alignment is achieved through a synchronous clock. The generated synchronous acquisition data stream is transmitted to the monitoring host, i.e., the processor. The host integrates a virtual rolling force model, micro-deformation displacement conversion, frequency domain decomposition processing, health status discrimination matrix, and dynamic correction module for mechanical reference. It is also equipped with a non-volatile memory for storing the environment compensation coefficient matrix. The processed maintenance warning signal is sent to the control terminal, i.e., the background management terminal, and the monitoring indicators are uploaded to the cloud database for group comparison and life prediction.

[0032] Example 4: In the parameter calibration scenario of a 40.5kV outdoor switchgear, the geometric contact form of the conductive contact unit is affected by assembly tolerances, and the preset structural constants... This batch of hardware cannot be directly adapted. If theoretical values ​​are used directly for calculation, the equivalent stiffness index... The resulting initial systematic error is no less than 15%, which cannot meet the requirements for quantitative inversion of electrodynamically induced micro-deformation; in order to determine the structural constants of the conductive contact unit... The system is calibrated using a load injection method. This method utilizes a hydraulic pressurizing device to apply mechanical pressure ranging from 500N to 1500N in 200N increments to the conductive contact units, and injects a 100A AC current at each pressure step. The processor synchronously records the contact resistance fluctuation amplitude at each pressure point and uses the least squares method to calculate the equivalent rolling force generated by the electrodynamic force. By performing a linear fit with the square term of the current, the structural constants of the current conductive contact unit are determined. for ;in, Equivalent rolling force, unit: N; The structure constant is expressed in units of 1 / 2. Regarding the determination of the cross-correlation threshold, the system conducted sensitivity tests on 2000 sets of feature signal samples under a signal-to-noise ratio environment of 15dB to 30dB. When the threshold is 0.8, the false judgment probability caused by incoherent mechanical vibration is less than 0.2%, and the capture integrity of the 100Hz feature component is 99.1%. Based on this, 0.8 is determined as the confidence judgment boundary for retaining the effective response signal.

[0033] In the virtual unloading procedure, the system initiates differential displacement sampling during periods when the load current is 5% below the rated value. The processor performs a moving average of the equivalent reduction in 100ms time units and monitors its variation with the equivalent rolling force. The rate of change during the process is reduced; when the absolute value of the rate of change at 5 consecutive sampling points is less than 0.01 μm / s, the contact interface is determined to have entered a physical unloading state, and the equivalent reduction value at this time is extracted as the residual deformation displacement. The unit is μm; the setting of the 30% warning threshold is based on the accelerated fatigue test data of the spring performance of the supporting components, when the equivalent stiffness index... After the attenuation of the nominal stiffness reached 28.5%, the stability of the contact pressure decreased by more than 50%, the contact resistance fluctuation entered the nonlinear growth region and induced local temperature rise. Based on this, a 30% deviation was determined as the logical upper limit for triggering a health warning. During 12 months of continuous monitoring and operation of the calibrated system, the equivalent stiffness index was adjusted using ambient temperature data. Corrections were made to separate the micro-creep displacement of the support from the effective response signal; through on-site calibration of structural constants and optimization of core threshold settings, the error between the health assessment results output by the system and the measured value of spring pressure after physical disassembly was within 3.2%; the monitoring method was based on the internal stress evolution state of the contact system, and the monitoring process was established using mechanical model parameters, which solved the problem of mapping distortion between the monitoring model and the hardware entity.

[0034] Example 5: In the field deployment and commissioning scenario of a 110kV high-voltage switchgear, due to the physical differences between the surface plating thickness and contact spot distribution of the conductive contact unit, the system determines the roughness correction factor by executing a pre-calibration procedure. An external pressure drive source is used to apply controlled mechanical excitation during contact closure, simultaneously recording the response trajectory of the contact resistance data. Based on Hertzian contact theory, the measured impedance nonlinearity characteristics are fitted to a preset material property curve, thereby converting the contact resistance fluctuation under measured current fluctuations into interface deformation displacement reflecting interface mechanical deformation. .

[0035] When the system faces long-term monitoring of switchgear in high humidity environments, the processor adjusts the weights of the health status discrimination matrix based on the ambient humidity data collected on-site. By reading the surface oxidation resistance coefficients at different humidity levels stored in non-volatile memory, the system performs temperature and humidity-coordinated compensation on the mechanical damping parameter judgment logic. This allows the system to eliminate interference signals generated by environmental factors, ensuring that the early warning signals generated during the health assessment output stage target the fatigue of the mechanical support springs of the conductive contact unit or the physical ablation of the contact interface. This deployment process based on pre-correction of environmental parameters solves the problem of false alarm drift in extreme climate regions.

[0036] Example 6: In a controlled temperature and humidity cycling environment verification scenario, the system executes a pre-deployment calibration process to construct a compensation database for the health status discrimination matrix. This process places the conductive contact unit under a step-cycle condition with a temperature range of -25℃ to 65℃ and a humidity range of 10% to 95%. The processor records the damping coefficient reference value of the contact interface at each physical steady-state point and calculates the difference between the damping coefficient offset under each environmental gradient and the nominal state, thereby generating a compensation coefficient matrix composed of temperature gradient and humidity gradient in the non-volatile memory. ,in, The compensation coefficient matrix is ​​a matrix in which each value represents the correction bias of the interface mechanical response weight under the corresponding temperature and humidity. The processor uses a cubic spline interpolation algorithm to smooth the discrete compensation points, so that the boundary weights of the discrimination matrix can achieve a linear transition when the ambient temperature and humidity change continuously.

[0037] When the system is applied to the health monitoring of switchgear in substations, the processor executes a standardized initial state self-test procedure before starting the monitoring process. The system measures the residual noise energy distribution under no-electrical-power excitation. The obtained values ​​are then matched with the gain coefficient of a 100Hz narrowband filter, where... Residual noise energy distribution, in units of If the measured signal-to-noise ratio (SNR) is below the performance boundary of 12dB, the processor automatically adjusts the width of the sliding sampling window from 500ms to 1200ms. If the SNR still does not meet the minimum operating requirement of 10dB after adjusting the sampling window, the system outputs a sensor link abnormality signal through the background management terminal and stops executing the early warning logic in the health assessment result output stage. This self-test procedure ensures that the equivalent stiffness index obtained in subsequent calculations is accurate. A quantization benchmark based on eliminating random electromagnetic disturbances.

[0038] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A monitoring method for the operational health management of switchgear, characterized in that, Includes the following steps: Step S1: Simultaneously acquire the load current data and contact resistance data of the conductive contact unit. Utilize the periodic electric repulsion characteristics generated by alternating current to determine the square term of the load current data as the equivalent rolling force acting on the contact interface of the conductive contact unit. Step S2: Utilize the micro-deformation response characteristics of the contact interface to convert the dynamic fluctuation of the contact resistance data into an equivalent reduction that characterizes the micro-displacement change of the contact interface. Step S3: Perform frequency domain decomposition on the equivalent rolling force and the equivalent reduction, extract the characteristic component with a frequency of 100Hz in the equivalent rolling force, and extract the coherent component with the same phase as the characteristic component from the equivalent reduction. Use the same frequency coherence to filter out the background interference signal in the equivalent reduction. Step S4: Calculate the amplitude ratio of the characteristic component and the coherent component, and determine the equivalent stiffness index of the conductive contact unit under the current working condition based on the amplitude ratio inversion. Step S5: Monitor load current data. When it is identified that the load current data is continuously below 5% of the rated current value during a low-load period, obtain the residual deformation of the conductive contact unit in the zero electrodynamic state, and use the residual deformation to correct the mechanical reference of the equivalent stiffness index. Step S6: Compare the deviation between the corrected equivalent stiffness index and the preset initial nominal stiffness. When the deviation exceeds the preset change threshold, output the evaluation result characterizing the mechanical fatigue state or interface oxidation degree of the conductive contact unit.

2. The monitoring method for the operational health management of switchgear according to claim 1, characterized in that, When performing step S1, the acquisition frequency of load current data and contact resistance data is not less than 10kHz; at the same time, the current acquisition channel and resistance acquisition channel are phase aligned using a synchronous clock so that the equivalent rolling force and the equivalent reduction form a causal response relationship in the time domain.

3. The monitoring method for the operational health management of a switchgear according to claim 1, characterized in that, In step S2, when converting the dynamic fluctuation of the contact resistance data into the equivalent reduction, a roughness correction factor that characterizes the distribution of conductive spots at the contact interface is introduced to linearize the nonlinear fluctuation of the contact resistance data into microscopic deformation displacement.

4. The monitoring method for the operational health management of a switchgear according to claim 1, characterized in that, When extracting coherent components in step S3, a window function is used to truncate the equivalent compression, and the cross-correlation coefficient between the equivalent compression and the standard 100Hz sine signal is calculated. Only signal components with cross-correlation coefficients exceeding a preset correlation threshold are retained as effective response signals for calculating the equivalent stiffness index.

5. The monitoring method for the operational health management of a switchgear according to claim 1, characterized in that, In step S4, when determining the equivalent stiffness index through inversion, the phase deviation between the characteristic component and the coherent component is extracted simultaneously, and the phase deviation is converted into the mechanical damping parameter of the conductive contact unit. By combining the equivalent stiffness index and the mechanical damping parameter into a two-dimensional vector, a health status discrimination matrix is ​​constructed.

6. The monitoring method for the operational health management of a switchgear according to claim 1, characterized in that, During dynamic correction in step S5, the residual deformation displacement is extracted by recording the trajectory evolution of the equivalent reduction during the low-load period, and the reference stiffness value is updated using the following formula: ,in, The updated reference stiffness value, The instantaneous equivalent rolling force at the moment of activation during low-load periods. This refers to the instantaneous equivalent reduction at the moment of startup during low-load periods. This represents the residual deformation displacement.

7. The monitoring method for the operational health management of a switchgear according to claim 5, characterized in that, When outputting the evaluation results in step S6, if the equivalent stiffness index decreases monotonically and the mechanical damping parameter remains stable, it is determined that the supporting component of the conductive contact unit has undergone stress relaxation; if the equivalent stiffness index remains stable and the mechanical damping parameter increases monotonically, it is determined that the oxide layer has thickened at the contact interface.

8. The monitoring method for the operational health management of a switchgear according to claim 1, characterized in that, After outputting the evaluation results, the following actions are performed: when the equivalent stiffness index falls below 70% of the initial nominal stiffness, a warning signal containing the risk of mechanical support failure is generated.

9. The monitoring method for the operational health management of a switchgear according to claim 1, characterized in that, Before performing step S6, the equivalent stiffness index is thermally corrected using ambient temperature, with the correction range covering -20°C. Up to 60 The elastic modulus of the peeling material fluctuates with seasonal temperature differences.

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