A method for monitoring a leakage of a gas-insulated medium voltage switchgear

Abstract

The application discloses a kind of for gas insulation medium voltage switchgear leakage monitoring method, it is related to leakage monitoring technical field, including in primary switch operation process, the displacement amount of contact movement and the amount of change of gas chamber pressure are synchronously collected;Contact movement displacement amount and pressure change amount are substituted into the physical relationship formula inherent to equipment to obtain an intermediate value, the physical relationship formula is established in advance based on gas chamber volume, contact movement effective area and gas state equation, and based on ideal gas adiabatic process, when the deviation between intermediate value and constant constant determined by equipment physical parameter exceeds the allowable range, it is judged that gas chamber exists gas leakage, the present application solves the problem that traditional monitoring method false alarm rate is high, cannot distinguish abnormal type, sensor failure cannot self-repair, global interference is difficult to exclude in multiple gas chamber equipment, gas composition change and leakage are easily confused, composite fault cannot be identified, transient interference leads to false alarm, common interference affects single direction monitoring.

Description

Technical Field

[0001] This invention belongs to the field of leakage monitoring technology, specifically a leakage monitoring method for gas-insulated medium-voltage switchgear. Background Technology

[0002] Gas-insulated medium-voltage switchgear, with its compact structure, high insulation performance, and resistance to harsh environments, is widely used in power systems. Its gas tightness directly determines the stability of equipment operation and the safety of the power grid. Current leakage monitoring methods are mainly divided into offline and online categories. Offline detection requires shutdown operation, which is cumbersome and time-consuming, cannot achieve real-time early warning, and is difficult to adapt to continuous operation requirements. Online monitoring mostly relies on a single sensor to collect gas chamber pressure information and judges the leakage status by comparing it with preset thresholds. This method is highly susceptible to interference from external factors such as ambient temperature fluctuations and changes in switch operating speed, resulting in a persistently high false alarm rate.

[0003] In actual operation, the contact movement speed naturally fluctuates during switch operation, and the ambient temperature also changes periodically. Both of these factors directly affect the accuracy of gas chamber pressure measurement. Increased temperature causes gas expansion, leading to a false increase in pressure, while changes in operating speed cause abnormal rates of change in gas chamber volume, resulting in instantaneous pressure fluctuations. These interferences from non-leakage factors are difficult to effectively eliminate using traditional single-parameter monitoring methods.

[0004] More importantly, after long-term operation, the contacts are prone to problems such as ablation and surface contamination, resulting in a deviation between the actual contact area and the effective area of ​​the initial design. Traditional solutions do not take into account such dynamic changes. At the same time, using only a single threshold to judge anomalies cannot distinguish between gas chamber leakage, blockage, excessive pressure, and slow leakage. It also cannot adaptively identify and correct sensor drift and known deviations. For equipment containing multiple independent gas chambers, it is also susceptible to interference from common factors such as shared pressure sources and global ambient temperature changes, which may lead to misjudgment of a single gas chamber leakage. Furthermore, it cannot distinguish between changes in gas composition and actual leakage, or the combination of leakage and mechanical failure. It is also more prone to false alarms due to transient sensor failures or external vibration interference. Monitoring data for unidirectional operation is also susceptible to the superimposed effects of fluctuations in operating speed, changes in ambient temperature, and sensor zero-point drift, which further exacerbates the decline in monitoring accuracy. Ultimately, this makes it difficult to detect minor leakage hazards in time, which may lead to serious consequences such as equipment insulation failure and fault tripping. Summary of the Invention

[0005] The purpose of this invention is to provide a leakage monitoring method for gas-insulated medium-voltage switchgear, so as to solve the problems mentioned in the background art.

[0006] A leakage monitoring method for gas-insulated medium-voltage switchgear includes: During a single switching operation, the displacement of the contact and the change in air chamber pressure are collected simultaneously. An intermediate value is obtained by substituting the displacement of the contact movement and the pressure change into the inherent physical relationship of the equipment. The physical relationship is based on the gas chamber volume, the effective area of ​​the contact movement and the gas state equation, and is based on the ideal gas adiabatic process. When the deviation between the intermediate value and the constant determined by the physical parameters of the equipment exceeds the allowable range, it is determined that there is a gas leak in the gas chamber; Under normal airtight conditions, the deviation between the intermediate value and the constant does not exceed the allowable range; leakage reduces the total amount of gas in the chamber, causing the intermediate value to deviate from the constant beyond the normal fluctuation range; and the physical relationship ensures that the effects of operating speed fluctuations and ambient temperature changes on the displacement of the contact and the change in pressure cancel each other out when calculating the intermediate value.

[0007] The "allowable range" is defined as follows: based on the median value calculated from 50 normal operations (airtight, rated inflation volume, 25℃±5℃) before the equipment leaves the factory, the standard deviation of the median value sequence is taken, and the allowable range is set as the interval formed by the constant constant minus three standard deviations to the constant constant plus three standard deviations (i.e., the 99.7% confidence interval). The standard deviation is dynamically updated during subsequent operation (recalculated every 20 additional normal operations).

[0008] The above method solves the problems of inaccurate pressure measurement and high false alarm rate caused by fluctuations in operating speed and changes in ambient temperature in traditional methods. By using a physical relationship, the effects of these two factors cancel each other out, retaining only the true changes caused by leakage.

[0009] In some possible implementations, the displacement of the contact movement is indirectly calculated by collecting multiple feature points in the waveform of the operating coil current and substituting them into the motion model, while the auxiliary contact state sequence is collected as a verification. When the alignment between the current waveform feature points and the auxiliary contact state sequence on the time axis meets the matching condition, the current waveform calculation result is used; when the alignment relationship deviates, the calculation of displacement is automatically switched to the auxiliary contact state sequence as the main method, and the current operation is marked as a suspected mechanical wear event.

[0010] This invention solves the problem that single displacement acquisition methods (such as relying solely on current waveforms or auxiliary contacts) are prone to failure under electromagnetic interference or mechanical wear. Through dual-source redundancy verification and automatic switching, the continuity and reliability of displacement data are ensured, and mechanical wear is identified simultaneously.

[0011] In some possible implementations, vibration signals during the contact movement are simultaneously acquired during a single switching operation; The energy attenuation characteristics at the moment of collision between the moving contact and the stationary contact are extracted from the vibration signal. The energy attenuation characteristics are used to correct the effective contact area parameter in the physical relationship to compensate for the change in contact area caused by contact erosion or surface contamination. Among them, there is a pre-defined mapping relationship between the energy attenuation characteristics and the effective area of ​​the contact, and the corrected effective area is actually substituted into the physical relationship.

[0012] This invention solves the problem that changes in the effective area of ​​contacts due to ablation or surface contamination after long-term operation, thus affecting the accuracy of volume calculation. It dynamically corrects the effective area parameters by extracting energy attenuation characteristics from vibration signals.

[0013] In some possible implementations, the direction and magnitude of the deviation of the intermediate value from the constant are handled separately: When the deviation direction is positive and the magnitude exceeds the first threshold, it is determined to be a gas chamber leak; When the deviation direction is negative and the magnitude exceeds the second threshold, it is determined that there is blockage in the air chamber or abnormally high pressure. When the deviation direction is positive but the magnitude does not exceed the first threshold, and the deviation magnitude of multiple consecutive operations shows an increasing trend, it is judged as a slow leak and an early warning is triggered. At the same time, the intermediate value of each operation is fed back to the gas state equation in the physical relation, and the total gas quantity parameter in the gas state equation is dynamically corrected to eliminate known deviations.

[0014] The above solution solves the problem of being unable to distinguish between different types of anomalies, such as leaks, blockages, excessive pressure, and slow leaks. By processing deviations in direction, magnitude, and trend separately, it enables the identification and early warning of multiple types of anomalies.

[0015] In some possible implementations, the steady-state pressure change rate and steady-state temperature change rate of the same gas chamber between two adjacent switching operations are collected; Compare the deviation of the steady-state pressure change rate from the median value: If the rate of change of steady-state pressure and the deviation of the median value change in the same direction and the ratio of their changes are within a certain range, then leakage is confirmed as the main cause. If the two changes are unrelated, then the deviation of the steady-state temperature change rate from the median value is further compared. When the deviation of the steady-state temperature change rate from the median value is in the opposite direction, it is determined to be a temperature sensor drift fault; when there is no correlation between the deviation of the steady-state temperature change rate from the median value, it is determined to be a pressure sensor zero-point drift fault. Based on the judgment result, different alarm types are output, and the corresponding self-calibration process is initiated.

[0016] This solves the problem of being unable to distinguish between leakage, temperature sensor drift, and pressure sensor zero-point drift. Through correlation analysis of steady-state pressure change rate, temperature change rate, and deviation from median values, it enables fault root cause identification and self-calibration.

[0017] In some possible implementations, for a device containing multiple independent air chambers and each air chamber having a different switching operating mechanism, the contact movement displacement and air chamber pressure change of each air chamber are collected respectively, and the intermediate value sequence of each air chamber is calculated by substituting them into the physical relationship formula. Calculate the average of the median values ​​for all chambers and the fluctuation range determined based on historical normal operating data, then compare the median value of each chamber with the average: When the median value of a certain air chamber exceeds the fluctuation range, while the median values ​​of other air chambers are all within the fluctuation range, the air chamber is determined to be leaking. When the median values ​​of multiple air chambers simultaneously exceed the fluctuation range in the same direction, it is determined that there is a global anomaly in the shared pressure source or ambient temperature. At this time, the air chamber with the smallest deviation is used as the reference benchmark, and the relative deviation of each air chamber is recalculated to eliminate global interference before making a judgment.

[0018] This solution addresses the problem in multi-chamber equipment where shared pressure sources or changes in ambient temperature can cause global interference, easily leading to normal chambers being misjudged as leaks. Through multi-chamber collaborative judgment and relative deviation calculation, global interference and localized leaks are separated.

[0019] In some possible implementations, during a single switching operation, the current curve of the drive motor of the operating mechanism is simultaneously acquired, and the operating power consumption is extracted from the current curve. The ratio of operating power consumption to contact displacement is used as an additional verification term, and a second constant relationship is established in parallel with the physical relationship: Under normal airtight conditions, the ratio of operating power consumption to contact displacement and pressure change satisfy a linear or piecewise linear relationship obtained through experimental calibration, which is determined by the mechanical efficiency of the equipment. When the intermediate value deviates from the constant but the second constant relationship still holds, it is determined to be a change in gas composition rather than a leak. When the median value deviates and the second constant relationship is broken at the same time, it is determined to be a combined fault of leakage and mechanical failure, and the contribution of leakage and mechanical failure are estimated respectively.

[0020] The above scheme solves the problems of easily confusing changes in gas composition (such as a decrease in SF6 purity) with actual leaks, and the difficulty in identifying a combination of leaks and mechanical failures. By introducing the ratio of operating power consumption to displacement as an additional verification term, a second constant relationship is established for differentiation and quantification.

[0021] In some possible implementations, the intermediate values ​​calculated for each switching operation are stored in chronological order to form a time series; A sliding window with a window length that is dynamically adjusted according to the number of operations is used to calculate the cumulative sum of the deviation of the intermediate value within the window in real time; It should be understood that a sliding window with a dynamically adjusted window length based on the number of operations is used. The adjustment rules are as follows: the initial window length is set to 5 operations; thereafter, the window length increases by 1 for every additional 10 operations; the maximum window length does not exceed 20 operations. If the device has not been used for an extended period (interval exceeding 30 days), the window length is reset to 5 for the next operation, and the accumulation process restarts. The cumulative sum of deviations from the intermediate values ​​within the window is calculated in real time.

[0022] When the accumulated value exceeds the control limit, a leakage alarm is triggered. At the same time, the intermediate value at the alarm time is used as a feedback signal to adjust the correction coefficient of the gas chamber volume parameter in the physical relationship. The intermediate value of subsequent normal operation returns to a constant, while the deviation caused by leakage is not compensated. The adjustment range of the correction coefficient is proportional to the alarm confidence level, and the adjustment process only takes effect after the alarm is cleared.

[0023] The above scheme solves the problem that single-operation judgments are easily affected by random fluctuations and it is difficult to identify cumulative leakage trends. By using a sliding window cumulative summation method, statistical judgment of leakage and adaptive correction of the gas chamber volume parameters are achieved.

[0024] In some possible implementations, after determining that there is a gas leak in the gas chamber, a final alarm is not immediately issued; instead, the following confirmation steps are performed: The active control switchgear performs an additional no-load operation, and the displacement of the contacts during the additional operation is set to be less than the normal operating displacement. The pressure change during the additional operation was collected and substituted into the same physical relationship to obtain the second intermediate value; Compare the deviation of the median value between the normal operation and the additional operation: if there is a predetermined proportional relationship between the two deviations and the respective operation displacement, which is proportional to the contact movement displacement, then leakage is confirmed; otherwise, it is determined to be a transient sensor fault or external vibration interference, and the alarm is canceled.

[0025] The above solution resolves the issue of false alarms caused by sensor transient failures or external vibration interference during a single operation. By proactively performing an additional no-load operation and verifying the proportional relationship between deviation and displacement, secondary confirmation of leakage is achieved.

[0026] In some possible implementations, during a single switching operation, the displacement of the contact movement and the change in air chamber pressure in both directions of the opening and closing operations are collected simultaneously, and then substituted into the physical relationship formulas to calculate the intermediate values ​​of the opening and closing operations. Under normal airtight conditions, the intermediate value of the opening circuit breaker and the intermediate value of the closing circuit breaker are equal and both are constant. When the absolute difference between the intermediate value of the opening circuit breaker and the intermediate value of the closing circuit breaker exceeds the threshold, it is determined that there is a gas leak in the air chamber. The calculation of the absolute difference offsets the effects of operating speed fluctuations, ambient temperature changes, and sensor zero-point drift on a single intermediate value. These interference factors produce deviations in the same direction and with approximately the same magnitude for the opening and closing operations. Furthermore, when both the opening and closing intermediate values ​​deviate from a constant, but the difference between the opening and closing intermediate values ​​is still less than the threshold, it is determined to be a change in gas composition or a global calibration error rather than a leak.

[0027] Specifically, it solves the problem that the intermediate value of unidirectional operation (opening or closing only) is affected by the superposition of common interferences such as operating speed, temperature, and sensor drift. Through bidirectional verification of opening and closing, the difference is used to cancel out common interferences, and changes in gas composition or calibration errors are identified simultaneously.

[0028] The technical solutions provided by the embodiments of this disclosure have at least the following beneficial effects: This invention simultaneously collects the displacement of the contact and the change in the gas chamber pressure during a single switching operation, and substitutes them into a pre-established physical relationship based on the gas chamber volume, the effective area of ​​the contact movement, and the gas state equation to calculate intermediate values. This allows the effects of operating speed fluctuations and ambient temperature changes on the calculation results to cancel each other out during the calculation process, thereby effectively eliminating non-leakage interference factors commonly found in traditional methods and significantly reducing the false alarm rate.

[0029] Based on the direction, magnitude, and trend of the deviation of the intermediate value from the constant, different anomaly types such as gas chamber leakage, slow leakage, blockage, excessive pressure, mechanical wear, gas composition change, and sensor drift can be identified, avoiding the confusion caused by traditional single threshold judgment.

[0030] By analyzing the correlation between the steady-state pressure change rate, the steady-state temperature change rate, and the deviation of the median value, the system can automatically determine temperature sensor drift or pressure sensor zero-point drift and initiate the corresponding self-calibration process without requiring downtime maintenance, thus improving the long-term stability and maintenance-free capability of the system.

[0031] For multi-chamber equipment, by calculating the average value and fluctuation range of the median values ​​of all chambers and combining it with relative deviation analysis, it is possible to effectively distinguish between global anomalies caused by shared pressure sources or changes in ambient temperature and actual leaks in a single chamber, thus avoiding misjudgments caused by global interference.

[0032] By introducing the ratio of operating power consumption to contact movement displacement as an additional verification item, a second constant relationship is established, which can distinguish between changes in gas composition and actual leakage. When leakage and mechanical failure coexist, the contribution of leakage and mechanical failure can be estimated respectively, providing a clear priority basis for operation and maintenance.

[0033] After initially determining a leak, an additional no-load operation is performed. By comparing the deviation of the median value between the two operations with the proportional relationship between the displacement, transient sensor faults or external vibration interference can be effectively ruled out, further improving the reliability of leak determination.

[0034] Simultaneously, the displacement and pressure changes during opening and closing operations are collected, the intermediate values ​​of opening and closing are calculated, and the difference between the two is used to determine leakage. This can offset common interferences such as operating speed fluctuations, ambient temperature changes, and sensor zero-point drift, thereby improving monitoring accuracy.

[0035] It provides early warning for slow leaks where the deviation from the target value increases over multiple consecutive operations, and feeds back the intermediate value of each operation to the gas state equation to dynamically correct the total gas parameters, eliminate known deviations, and achieve long-term stable monitoring. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the method structure of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please see Figure 1 This application provides a leakage monitoring method for gas-insulated medium-voltage switchgear, comprising: For equipment containing multiple independent air chambers with different switching operating mechanisms, the displacement of the contact and the change in air chamber pressure are collected for each air chamber, and the intermediate value sequence of each air chamber is calculated by substituting them into the physical relationship formula.

[0039] It should be noted that each air chamber is independently equipped with a corresponding current sensor (sampling accuracy ≤0.1%FS), auxiliary switch (contact action error ≤±1ms), pressure acquisition device (measurement range 0-1.6MPa, accuracy ≤0.2%FS), and vibration sensor (sampling frequency 1kHz-10kHz, range ±50g) to ensure that the signal acquisition of each air chamber does not interfere with each other and the data is independent.

[0040] For each air chamber, the acquisition logic for a single air chamber is followed: The displacement of the contact is calculated by collecting characteristic points of the operating coil current waveform and combining them with the motion model. The auxiliary contact state sequence is collected and verified simultaneously. The pressure change in the gas chamber and the vibration signal during the contact movement are collected. The collision energy attenuation characteristics are extracted from the vibration signal, and the effective contact area parameter in the physical relationship is corrected. The displacement and pressure change are substituted into the physical relationship to calculate the intermediate value corresponding to each opening and closing operation of the air chamber. After multiple operations, an independent intermediate value sequence for each air chamber is formed (the sequence length is no less than 5 operations to ensure the validity of data statistics).

[0041] This design enables independent monitoring and data separation of multiple chambers, laying the foundation for subsequent collaborative judgment, avoiding the impact of single chamber failure or interference on the overall monitoring results, while maintaining the consistency of the monitoring logic of each chamber and ensuring data comparability.

[0042] Beneficial effects: Multi-chamber equipment is prone to global disturbances during operation, such as fluctuations in the shared pressure source and synchronous changes in ambient temperature. Traditional monitoring methods often misjudge global disturbances as leaks in a single chamber. This solution achieves mutual isolation between chambers by independently collecting and calculating intermediate values ​​for each chamber, effectively distinguishing between local anomalies and global disturbances, and improving the accuracy of leak detection in multi-chamber equipment.

[0043] Calculate the average of the median values ​​of all chambers and the fluctuation range determined based on historical normal operating data, and compare the median value of each chamber with the average value.

[0044] Specifically, the average value of all air chamber intermediate values ​​is calculated as follows: take the arithmetic mean of the intermediate values ​​of each air chamber within the same time period (or under the same number of operations), that is, the sum of all air chamber intermediate values ​​divided by the number of air chambers. The average value is updated in real time and recalculated after each new operation data.

[0045] The fluctuation range is calibrated based on historical normal operating data: 100 sets of continuous normal operating data were selected after the equipment left the factory and confirmed to be well sealed through airtightness test (pressure retention rate ≤0.1% / day). Obvious abnormal points caused by external interference (points where the median value deviates from the average value by more than four times the standard deviation) were removed. The median standard deviation of the remaining data was calculated. The fluctuation range was set as the range from the average value minus two times the standard deviation to the average value plus two times the standard deviation (covering 95.45% of the normal data distribution, the coefficient can be adjusted to 1.5 times or 3 times the standard deviation according to the equipment accuracy requirements). The fluctuation range is updated in real time with the average value to ensure that it adapts to the baseline drift of the equipment during long-term operation.

[0046] The difference between the current median value and the average value of each air chamber is calculated to determine whether the difference falls within the fluctuation range, providing a quantitative basis for subsequent anomaly attribution judgment.

[0047] By comparing the average values ​​of multi-chamber data and statistically analyzing the fluctuation range, it is possible to effectively separate local anomalies in a single chamber from common anomalies in multiple chambers, avoiding misjudging global interference as local leakage and improving the accuracy of monitoring complex equipment. This design is particularly critical for multi-chamber equipment, solving the pain point that traditional single-chamber independent judgment cannot eliminate global interference.

[0048] By using the above method and taking the average value of multiple air chambers as a benchmark, the overall deviation caused by common factors such as ambient temperature and air source pressure can be offset. Combined with the dynamic fluctuation range, the air chambers that are truly deviating from the normal state can be identified more stably, reducing misjudgments caused by fluctuations in operating conditions.

[0049] When the median value of a certain air chamber exceeds the fluctuation range, while the median values ​​of other air chambers are all within the fluctuation range, the air chamber is determined to be leaking.

[0050] The median value of a certain air cell exceeds the range formed by the average minus twice the standard deviation to the average plus twice the standard deviation, while the median values ​​of the other air cells all fall within the fluctuation range. This indicates that the anomaly exists only in a single air cell and there is no global common interference. Combined with the previous judgment results on the direction and magnitude of the deviation of the median value, it is preliminarily determined that there is a leak (or slow leak) in this air cell.

[0051] This judgment rule provides a basis for the initial screening of leaks. Subsequent confirmation steps are required to eliminate transient interference and improve the reliability of leak determination.

[0052] Specifically, a leak is only determined when a single air chamber is abnormal and the rest of the air chambers are normal. This can directly eliminate the influence of overall environmental fluctuations and make the leak judgment more closely reflect the actual state of the equipment.

[0053] When the median values ​​of multiple air chambers simultaneously exceed the fluctuation range in the same direction, it is determined that there is a global anomaly in the shared pressure source or ambient temperature. At this time, the air chamber with the smallest deviation is used as the reference benchmark, and the relative deviation of each air chamber is recalculated to eliminate global interference before making a judgment.

[0054] If the median values ​​of multiple air chambers (≥2) simultaneously exceed the fluctuation range in either a positive or negative direction, it indicates the presence of a global factor affecting all air chambers, such as abnormal pressure from a shared pressure source or significant temperature changes in the environment where the equipment is located. The criterion for determining the air chamber with the smallest deviation is: Calculate the absolute value of the difference between the median value of each abnormal gas chamber and the boundary of the fluctuation range. Take the gas chamber with the smallest absolute value of the difference as the reference benchmark (this gas chamber is least affected by local leakage and is closest to the normal state), and record its median value as the median value of the reference benchmark.

[0055] Recalculate the relative deviation of each chamber: the deviation of the reference chamber from the original mean is the median value of the reference reference minus the average value; the deviation of other chambers from the reference chamber is the median value of each chamber minus the median value of the reference reference. Using the median value of the reference chamber as the new baseline, reset the local fluctuation range to the interval formed by the median value of the reference reference minus the standard deviation of the historical normal data of the reference chamber to the median value of the reference reference plus that standard deviation (this standard deviation is calculated based on at least 30 sets of normal operating data). Determine whether the deviation of each chamber from the reference chamber exceeds the local fluctuation range.

[0056] If the deviation of a certain air chamber from the reference air chamber exceeds the local fluctuation range, it indicates that in addition to global disturbance, there is also a possibility of local leakage in that air chamber, and further confirmation steps are required; if the deviation of all air chambers from the reference air chamber is within the local fluctuation range, it indicates that there is only a global anomaly and no single air chamber leakage.

[0057] This design enables the separation and judgment of global interference and local leakage, which not only avoids misjudgment of multiple chambers caused by global interference, but also accurately identifies suspected local leakage in the presence of global interference, providing a screening basis for subsequent confirmation steps.

[0058] Beneficial effect: When multiple air chambers are abnormal at the same time, the most stable air chamber is used as a reference first to eliminate the common deviation caused by global factors, and then it is determined whether there is a local leak. It can still maintain accurate judgment under complex working conditions.

[0059] During a single switching operation, the displacement of the contact and the change in air chamber pressure are simultaneously collected. Vibration signals during the contact movement are also collected, as are the current curves of the drive motor of the operating mechanism. The operating power consumption is extracted from the current curves. The displacement of the contact and the change in air chamber pressure in both the opening and closing operations are collected and substituted into the physical formulas to calculate the intermediate values ​​for opening and closing.

[0060] The current curve of the operating mechanism drive motor is collected by a high-precision current sensor (sampling frequency 1kHz-5kHz, accuracy ≤0.1%FS) connected in series in the motor power supply circuit. It covers the current changes in the entire process of motor start-up, operation and braking. The collection time is from the moment the motor starts to the moment the motor stops, ensuring that the current waveform of the entire operation process is completely captured.

[0061] The steps for extracting operating power consumption are as follows: The first step is to perform synchronous integration calculations on the collected current curve and the motor's rated voltage (the rated value on the motor nameplate, with an error ≤ ±1%) to obtain the instantaneous power curve, where the instantaneous power is equal to the product of the rated voltage and the instantaneous current value; The second step is to integrate the instantaneous power curve over the entire operation time to obtain the total power consumption during the operation. The integration interval is from the start time of the motor to the stop time, and the integration step size is ≤1ms. The third step is to eliminate the motor idling power consumption (measured by the equipment factory test when the motor is without load, stored in the data processing unit, and measured at an ambient temperature of 25℃±5℃) to obtain the effective operating power consumption. The effective operating power consumption is equal to the total power consumption minus the idling power consumption. The effective operating power consumption directly reflects the sum of the mechanical resistance and air chamber pressure resistance overcome by the drive contact movement.

[0062] Signal acquisition for opening and closing operations is performed synchronously: during the complete "opening-closing" cycle, the contact displacement, air chamber pressure change, and vibration signal are acquired separately for the opening and closing stages.

[0063] The displacement during opening and closing operations is collected by the same current sensor and auxiliary switch to ensure consistent measurement reference. The pressure change is continuously collected by the same pressure sensor at a sampling frequency of 1kHz. The pressure data during the opening and closing stages are divided according to the operation sequence (the opening stage is from motor start to the completion of the opening auxiliary contact action, and the closing stage is from the completion of the opening to the completion of the closing auxiliary contact action). The vibration signal is also divided into opening vibration characteristics and closing vibration characteristics according to the time sequence.

[0064] The calculation logic for the intermediate values ​​of opening and closing is completely consistent: Collision energy attenuation characteristics are extracted from the vibration signals of opening and closing respectively (the collision time is the moment when the vibration signal amplitude first exceeds the threshold, the threshold is 3 times the average amplitude of normal operation, and the energy attenuation coefficient is the amplitude attenuation rate within 0.1s after the collision), and the corresponding effective contact area is corrected using the following formula: ;in, The corrected effective area. The initial effective area (determined by the contact structure dimensions) , (where the contact radius is...) This is a correction factor (factory calibration value range: 0.8–1.2). The normalized energy deviation is defined as the difference between the normal vibration energy and the measured vibration energy divided by the normal vibration energy. The change in opening volume is equal to the product of the effective area after opening correction and the opening displacement (volume increases), and the change in closing volume is equal to the product of the negative effective area after closing correction and the closing displacement (volume decreases, closing displacement is positive). The absolute pressure for opening the circuit breaker is equal to the initial static pressure of the air chamber plus the change in opening pressure. The absolute pressure for closing the circuit breaker is equal to the initial static pressure of the air chamber plus the change in closing pressure (the initial static pressure of the air chamber is collected within 30 seconds before operation, and the stabilization time is ≥5 seconds); the initial volume of the air chamber is a factory-fixed parameter.

[0065] Substituting the above parameters into the unified physical formula, we obtain the intermediate values ​​for opening and closing: The intermediate value of the tripping valve is equal to the product of the absolute pressure of the tripping valve and the actual volume of the tripping valve, where the actual volume of the tripping valve is equal to the initial volume of the air chamber plus the change in the tripping valve volume. The closing intermediate value is equal to the product of the closing absolute pressure and the closing actual volume, where the closing actual volume is equal to the initial volume of the air chamber plus the change in closing volume (the change in closing volume is negative, reflecting a decrease in volume).

[0066] The above calculations ensure that the intermediate value is comparable to the constant, and that the direction of volume reduction during closing is correctly reflected by the sign of the volume change.

[0067] This design establishes a bidirectional comparison benchmark through bidirectional data acquisition and independent calculation of opening and closing circuits, providing data support for offsetting common interferences, while maintaining the consistency of the opening and closing calculation logic to ensure the comparability of intermediate values.

[0068] By using bidirectional calculations and comparisons to minimize the impact of common disturbances such as temperature, speed, and sensor drift during the opening and closing processes, the true changes caused by leakage can be highlighted.

[0069] Specifically, the displacement of the contact movement is indirectly calculated by collecting multiple feature points in the waveform of the operating coil current and substituting them into the motion model, while the state sequence of the auxiliary contact is collected as a verification.

[0070] The operating coil current waveform is acquired by a current sensor connected in series in the circuit. The acquisition frequency is set from 1kHz to 10kHz, covering the main frequency bands of current waveform changes. This ensures that three key feature points can be captured: the rising edge inflection point (current slope ≥ 5A / ms for the first time), the peak point (maximum current value), and the falling edge inflection point (current slope ≤ -5A / ms for the first time). Each feature point corresponds to a contact movement stage.

[0071] The motion model is pre-established based on the mechanical transmission characteristics of the switching equipment. The model expression is that displacement equals the product of the electromagnetic force coefficient and the current value minus the product of the damping coefficient and the velocity, minus the static friction coefficient, and then the integral over time (where the electromagnetic force coefficient, damping coefficient, and static friction coefficient are obtained through calibration before the equipment leaves the factory). The calibration method for each coefficient is as follows: Before the equipment leaves the factory, under the condition of keeping the air chamber sealed and no load, the operating mechanism is driven with 50%, 75%, and 100% of the rated voltage, respectively. The current waveform and the measured contact displacement are collected (calibrated by a laser displacement sensor with an accuracy of ±0.1mm). The least squares method is used to fit each coefficient, and the correlation coefficient of the fitting is not less than 0.95, and the calibration error is ≤±5%. The velocity is obtained by differentiating the displacement with respect to time. The contact displacement is obtained by integrating the dynamic equation with the timestamp of the current characteristic point and the current amplitude as input.

[0072] The auxiliary contact state sequence is acquired by the auxiliary switch linked to the contact. The moment of contact state change is strictly synchronized with the contact travel position, with a synchronization error of no more than ±1ms. During acquisition, the precise timestamp of each state change is recorded to form a time sequence.

[0073] This invention utilizes current waveforms to continuously calculate displacement, improving time resolution; at the same time, it uses auxiliary contacts for position verification to avoid displacement calculation distortion caused by electromagnetic interference, making displacement data more stable and reliable.

[0074] When the alignment relationship between the current waveform feature points and the auxiliary contact state sequence on the time axis meets the matching condition, the current waveform calculation result is used.

[0075] Specifically, the matching conditions are determined by experimental data under normal operating conditions: the time difference between the rising edge inflection point of the current and the start of contact movement of the auxiliary contact is ≤ ±3ms; the time difference between the peak point and the midpoint of the contact stroke of the auxiliary contact is ≤ ±3ms; and the time difference between the falling edge inflection point and the contact's final position of the auxiliary contact is ≤ ±3ms. When all three conditions are met simultaneously, the alignment relationship is considered to satisfy the matching conditions. Using the current waveform calculation results provides higher time resolution and more accurately reflects the continuous movement process of the contact, providing high-precision displacement data for subsequent calculations.

[0076] Beneficial effects: When the current signal is reliable and consistent with the mechanical action, high-precision continuous displacement is preferred, which can improve the accuracy of pressure and volume calculations.

[0077] When an alignment deviation occurs, the system automatically switches to calculating the displacement primarily based on the auxiliary contact state sequence and marks the current operation as a suspected mechanical wear event. If the time difference between any feature point and the corresponding auxiliary contact state change exceeds ±3ms, it is considered an alignment deviation. Using the auxiliary contact calibration stroke as a reference, linear interpolation is employed to calculate the displacement (e.g., the tripping stroke is the total displacement; the auxiliary contact action is divided into three nodes: 0%, 50%, and 100%, with the intermediate position obtained through linear interpolation between adjacent nodes; the interpolation error is ≤±1%), ensuring uninterrupted monitoring. Simultaneously, the system records operation time, current characteristics, state sequence, and deviation values, marking these as suspected mechanical wear events to provide a basis for preventative maintenance. This dual-source fault-tolerant mechanism avoids monitoring interruptions caused by a single signal failure, while also enabling joint monitoring of mechanical and airtight conditions, thus improving the overall reliability of the system.

[0078] Specifically, when the current signal is abnormal, it automatically switches to a more stable auxiliary contact to calculate the displacement, ensuring uninterrupted monitoring; at the same time, it identifies wear of mechanical parts in advance through timing deviations, achieving early warning of potential hazards.

[0079] The pressure change in the air chamber is obtained through a pressure acquisition device directly connected to the air chamber. It is the difference between the current real-time pressure and the initial static pressure, with a measurement error not exceeding ±0.001MPa. This is used to accurately reflect the dynamic changes in air chamber pressure during operation.

[0080] Vibration signals are collected by a piezoelectric vibration sensor installed on the equipment housing near the contact transmission mechanism. The collection frequency covers the main frequency range of contact collision (100Hz-5kHz) and is synchronized with the displacement and pressure signals using the same clock (clock accuracy ≤±1μs) to ensure strict alignment of the time axis.

[0081] Extract the energy attenuation characteristics at the moment of collision between the moving and stationary contacts from the vibration signal. The specific algorithm is as follows: The envelope is obtained by performing a Hilbert transform on the vibration signal; The collision moment is defined as the point in time when the envelope amplitude first exceeds three times the normal operating average amplitude. The energy decay coefficient is calculated as follows: The energy decay coefficient is equal to the ratio of the time required for the envelope to drop from the peak value to one-tenth of the peak value to the standard time, where the standard time is the average of 10 normal operations measured when the equipment leaves the factory with the contacts intact.

[0082] The energy decay characteristic is composed of the total energy at the moment of collision (the integral value of the envelope within 0.1s after the collision) and the energy decay coefficient.

[0083] Correcting the effective contact area parameter in the physical formula using energy attenuation characteristics: The corrected effective area Replace the effective contact area parameter in equation (1) and recalculate the volume change. and actual volume Then, substitute it into equation (1) to calculate the intermediate value M to compensate for the change in contact area caused by contact erosion or surface contamination. Among them, there is a pre-calibrated mapping relationship between the energy attenuation characteristics and the effective contact area. During calibration, in a leak-free and constant temperature environment, the contact area of ​​the contact is changed and vibration signals are collected simultaneously to establish a one-to-one correspondence between the energy attenuation coefficient and the effective area, thus forming a calibration curve.

[0084] The corrected effective area was then substituted into the physical relational formula.

[0085] It should be noted that the mapping relationship is calibrated experimentally during the factory or maintenance phase: using the initial effective area (Determined by the contact structure dimensions,) Using r (where r is the contact radius) as a benchmark, different ablation and contamination states were simulated (different contact areas were achieved by sanding the contact surface; the contact area was measured using a laser rangefinder with an accuracy ≤ ±0.01 mm²). Vibration characteristics were collected and the effective area was measured. A stable mapping relationship was obtained through bivariate polynomial fitting, and the corrected effective area was determined. Calculate directly using the following formula: ; Where a is the coefficient of the quadratic term, b is the coefficient of the linear term, and c is the constant term. This is the normalized energy decay coefficient. The polynomial directly outputs the corrected effective area. Used to replace the initial effective area The volume change involved in the physical relation (1) is calculated as ΔV = ·s; For a typical medium-voltage switchgear (contact radius 15mm, initial effective area A0≈707mm²), the calibrated example coefficients are: a=-0.023, b=1.86, c=680 (unit: mm²). Dimensionless), fitting error ≤ ±3%. Verification is required after calibration: when... =0 (contact in good condition), calculated by the above formula With the initial effective area The deviation should be ≤±5% to ensure that the correction benchmark is consistent with the initial design. In actual use, each piece of equipment should be recalibrated based on its own structure.

[0086] This mapping relationship is stored in the data processing unit and accessed in real time. After real-time correction, the volume change calculation more closely matches the actual structure of the equipment, avoiding systematic parameter deviations caused by long-term operation.

[0087] This invention establishes an accurate correspondence between vibration characteristics and effective area through offline experiments, and directly uses calibration results for correction during online operation, ensuring that area compensation is stable and reproducible, and will not have calculation deviations due to changes in operating conditions.

[0088] The intermediate value is obtained by substituting the contact displacement and pressure change into the inherent physical relationship of the equipment. The physical relationship is based on the gas chamber volume, the effective contact movement area, and the gas state equation, and the following standard expression is used throughout the text: (1); where, This is an intermediate value, in Pa⋅m³. The absolute pressure of the air chamber is determined by the initial static pressure of the air chamber. Pressure changes during operation The result of superposition is that ; This is the actual volume of the air chamber, derived from the initial volume of the air chamber. Volume change caused by contact movement The result of superposition is that And the change in volume for Corrected effective contact area This represents the displacement of the contact movement. Initial volume of air chamber These are factory-fixed parameters (determined by equipment design drawings, calibrated by hydrostatic method, calibration error ≤ ±1%), obtained from actual measurement of cavity dimensions. The initial value of the effective contact area is uniquely determined by the contact structure dimensions (initial effective area). , The effective area is obtained after vibration characteristic correction (where the contact radius is ≤ ±0.01 mm). .

[0089] The physical equations are based on the adiabatic process of an ideal gas. The switching operation time is less than 1 second, and the heat exchange between the gas and the outside is negligible, satisfying the conditions for an adiabatic process. When the gas is airtight and the total gas volume remains constant, the product of the absolute pressure and the actual volume remains constant, that is, the intermediate value M is a constant.

[0090] Throughout the text, whenever "substitute into the physical relation" is mentioned, it refers to substituting each item into the formula (1) and the above parameter definitions for calculation.

[0091] It should be noted that for real gases (such as SF6), when the pressure is higher than 1.0 MPa, a compressibility factor correction can be introduced. That is, the intermediate value is equal to the product of the compressibility factor, the absolute pressure of the gas chamber, and the actual volume of the gas chamber. However, this embodiment uses an ideal gas as an example for explanation.

[0092] It should be understood that under normal airtight conditions, the intermediate value is always equal to the constant. The calibration method for the constant is as follows: before the equipment leaves the factory, under the conditions of keeping the gas chamber sealed, the total gas volume at the rated filling volume, and an ambient temperature of 25℃±5℃, perform at least 10 standard operations, and take the average of the intermediate values ​​obtained from each calculation as the constant. The unit of the constant is Pascals multiplied by cubic meters, and it is stored in the data processing unit as a subsequent judgment benchmark.

[0093] Under normal airtight conditions, the intermediate value of the opening circuit breaker and the intermediate value of the closing circuit breaker are equal and both are constant. When the absolute difference between the intermediate value of the opening circuit breaker and the intermediate value of the closing circuit breaker exceeds the threshold, it is determined that there is a gas leak in the air chamber.

[0094] When the airtightness is normal, although the volume change during the opening and closing operations are in opposite directions, the total amount of gas in the air chamber remains unchanged. According to the ideal gas law, the product of pressure and volume during the opening process should be equal to the product of pressure and volume during the closing process. That is, the intermediate values ​​of opening and closing are both equal to a constant (the constant is calibrated by the airtightness test at the factory, with a calibration environment temperature of 25℃±5℃ and a pressure of 0.6MPa±0.05MPa).

[0095] The absolute difference threshold is calibrated through factory testing: With the air chamber sealed, perform 50 sets of "opening-closing" cycle operations, calculate the absolute value of the difference between the intermediate value of opening and the intermediate value of closing for each set, and take 1.5 times the maximum value among these absolute values ​​as the threshold (usually set to ±2% of a constant to ensure coverage of the normal mechanical error range).

[0096] When the absolute value of the difference between the opening and closing intermediate values ​​is greater than the threshold, it indicates that the total gas volume is inconsistent during the opening and closing processes. Gas leakage after opening leads to a reduction in the total gas volume during closing, indicating that there is gas leakage in the gas chamber, and proceeding to the subsequent confirmation steps.

[0097] This two-way verification mechanism directly targets changes in the total gas volume caused by a leak, and is not affected by interference factors in a single operation, thus improving the anti-interference capability of leak detection.

[0098] When the airtightness is normal, the total amount of gas remains unchanged when the circuit breaker is open and closed, and the two intermediate values ​​are basically the same. Once a leak occurs, the total amount of gas changes between the open and closed circuits, and the two intermediate values ​​will show a significant difference. This makes the leak judgment more closely resemble the real physical process of gas state change.

[0099] The calculation of the absolute difference offsets the effects of operating speed fluctuations, ambient temperature changes, and sensor zero-point drift on a single intermediate value. These interference factors produce deviations in the same direction and with approximately the same magnitude for both opening and closing operations.

[0100] Fluctuations in operating speed can cause instantaneous peak changes in pressure. However, the speed fluctuations in opening and closing operations are caused by factors such as inertia and friction of the same mechanical mechanism. The influence on the intermediate values ​​of opening and closing is in the same direction and has similar amplitude (deviation difference ≤ ±5%). The change in ambient temperature is continuous within a short "opening-closing" cycle (cycle duration ≤ 30s), and has the same effect on the pressure measurement of opening and closing (pressure deviation caused by temperature change ≤ ±0.005MPa); the zero-point drift of the sensor is a fixed deviation (zero-point drift of pressure sensor ≤ ±0.001MPa, zero-point drift of current sensor ≤ ±0.01A), which will be synchronously superimposed on the pressure change of opening and closing, causing the intermediate value of opening and closing to shift in the same direction.

[0101] By calculating the absolute value of the difference between the opening and closing intermediate values, the deviations of the above-mentioned common interference factors cancel each other out, and only the differential signal of the change in the total amount of gas caused by leakage is retained, thus solving the technical pain point of traditional single-direction monitoring being susceptible to multiple interferences.

[0102] Beneficial effects: The effects of interference such as temperature, speed, and sensor drift on opening and closing are similar. By calculating the difference, these common deviations can be largely offset, leaving only the real changes caused by leakage, thus improving the stability of the judgment.

[0103] Furthermore, when both the opening and closing intermediate values ​​deviate from a constant, but the difference between the opening and closing intermediate values ​​is still less than the threshold, it is determined to be a change in gas composition or a global calibration error rather than a leak.

[0104] If both the opening and closing intermediate values ​​deviate from the constant (the deviation is greater than 2% of the constant), but the absolute value of the difference between the opening and closing intermediate values ​​is less than or equal to the threshold, it indicates that the total amount of gas is consistent during the opening and closing processes, and no leakage occurs.

[0105] The main causes of deviations are changes in gas composition (such as SF6 gas mixing with air, leading to changes in the gas constant in the gas law equation; significant deviations will occur when the change in the gas constant is ≥5%) or global calibration errors (such as initial volume calibration deviations or drift in mechanical efficiency reference values, with deviations ≤±3%). In this case, an alarm for changes in gas composition or calibration errors will be output to prompt maintenance personnel to perform gas detection or equipment calibration, rather than a leak alarm.

[0106] This judgment rule further distinguishes between synchronous deviations between leaks and non-leaks, avoiding misjudging non-leakage issues such as changes in gas composition and calibration errors as leaks, and improving the accuracy of anomaly diagnosis.

[0107] Beneficial effects: Changes in gas composition or overall calibration deviations will cause the intermediate values ​​of opening and closing to shift synchronously, but will not change the difference between the two; while leakage will significantly widen the difference. This characteristic allows for accurate differentiation between leakage and gas quality or calibration problems.

[0108] The direction and magnitude of the deviation of the intermediate value from the constant are handled separately. The constant is the standard product value when the equipment is well sealed and the total gas volume is stable. It is obtained by multiplying the initial static pressure and the initial volume of the gas chamber before leaving the factory (the constant is equal to the product of the calibrated static pressure and the calibrated initial volume), and serves as a fixed reference.

[0109] The direction of deviation is determined by the difference between the median value and the constant. A median value greater than the constant is considered a positive deviation, and a median value less than the constant is considered a negative deviation. The magnitude of deviation is calculated using relative error, which is the absolute value of the difference between the median value and the constant, divided by the constant, and then multiplied by 100%, uniquely representing the degree of deviation as a percentage. Processing direction and magnitude separately allows for precise differentiation of different anomaly types, avoiding misjudgments caused by a single threshold.

[0110] It should be understood that different faults correspond to different directions of pressure and volume changes. Treating the deviation direction and magnitude separately can more precisely distinguish between different anomalies such as leakage, blockage, and excessive pressure.

[0111] When the deviation is positive and the magnitude exceeds the first threshold, it is determined to be a gas chamber leak. A positive deviation indicates that the pressure drop in the gas chamber under the same volume change is less than theoretically expected. According to the ideal gas law PV=nRT, the total gas volume n is constant under normal airtightness, and is an intermediate value. Maintain a constant pressure. After a leak occurs, the total gas volume decreases. Under the same volume change ΔV, the pressure change response weakens, and the measured pressure drop is less than theoretically expected. The calculated median value is greater than the constant, showing a positive deviation, corresponding to the leakage physical mechanism of a decrease in total gas volume. The deviation is calculated using a fixed formula: the absolute value of the difference between the median value and the constant, divided by the constant, and then multiplied by 100%. The first threshold is calibrated based on the equipment's maximum allowable leakage rate.

[0112] The calibration method is as follows: A micropore with a diameter of approximately 0.1 mm is machined into the gas chamber to simulate a slow leakage rate of 0.5% per year. Under normal operating conditions, the median value of 50 consecutive operations is collected. The deviation of each median value from the constant is calculated, and the average of these 50 deviations plus three times the standard deviation is taken as the first threshold. For typical medium-voltage switchgear (gas chamber volume 50L~300L, rated pressure 0.4MPa~0.7MPa), this threshold is approximately 3%. Other specifications of equipment should be recalculated according to the above calibration method.

[0113] Beneficial effects: Leakage reduces the total amount of gas in the gas chamber, resulting in a smaller pressure drop for the same volume change, and the median value shows a positive deviation. Combined with the amplitude judgment, the leakage status can be stably identified.

[0114] When the deviation is negative and exceeds the second threshold, it is determined that there is blockage or excessive pressure in the air chamber. A negative deviation indicates an abnormal increase in pressure or restricted volume change, corresponding to air chamber blockage, excessive pressure, or mechanical jamming. The second threshold is calibrated based on the equipment's maximum allowable pressure. The calibration method is as follows: slowly increase the air chamber pressure to 1.1 times the equipment's rated pressure (simulating blockage or excessive pressure), collect the median value of 50 operations under normal operating conditions, calculate the relative deviation of each median value from the constant (relative deviation equals the median value minus the constant, divided by the constant, and multiplied by 100%), and take the lower quartile (or minimum value) of these 50 relative deviations, then shift it downwards by one standard deviation as the second threshold (expressed as a negative value). For example, if the mean of the 50 relative deviations is -4.2% and the standard deviation is 0.6%, then the second threshold can be set to -4.8% (i.e., mean minus one standard deviation). For typical equipment, this threshold is approximately -5% of the constant. Using the mean minus one standard deviation instead of three standard deviations avoids situations where excessively negative values ​​prevent the threshold from being physically achieved. Similarly, other equipment specifications should be recalibrated.

[0115] Beneficial effects: When there is blockage or excessive pressure, the volume change is hindered and the pressure rises abnormally. The median value shows a negative deviation, which can be clearly distinguished from leakage, and realize the automatic identification of multiple types of anomalies.

[0116] When the deviation direction is positive but the magnitude does not exceed the first threshold, and the deviation magnitude of multiple consecutive operations shows an increasing trend, it is judged as a slow leak and an early warning is triggered. A positive deviation but not exceeding the limit indicates that the gas loss is small. A deviation magnitude of multiple consecutive operations showing an increasing trend (the magnitude of the later operation is ≥0.5% larger than the previous one) indicates that the leak is continuously aggravating. Early slow leaks can be identified in advance by judging the trend, and an early warning can be output without additional confirmation.

[0117] Beneficial effects: Slow leaks may not show obvious changes in a single operation, but they will gradually accumulate over multiple operations. By judging the continuous trend, weak leaks can be detected in advance, achieving early warning.

[0118] Simultaneously, the intermediate value of each operation is fed back to the gas equation of state in the physical relation, dynamically correcting the total gas quantity parameter to eliminate known deviations. After each operation, the known deviation between the intermediate value and the constant is substituted into the gas equation of state, and the correction formula is: the corrected gas molar quantity equals the molar quantity after the previous correction plus the measured deviation of the intermediate value divided by the product of the gas constant and the real-time temperature of the gas chamber; The corrected gas molar quantity is the corrected total gas quantity parameter, the previously corrected molar quantity is the result of the previous correction, the gas constant is a known physical constant, and the real-time temperature of the gas chamber is collected by a temperature sensor (accuracy ≤ ±0.5℃). The measured deviation of the intermediate value is the intermediate value calculated in this operation minus the intermediate value that should be obtained in this operation if there is no leakage. The intermediate value if there is no leakage is taken as follows: when no leakage alarm is triggered, the intermediate value if there is no leakage is equal to a constant. When a leakage alarm has been triggered but not yet deactivated, the system assumes that the intermediate value for no leakage remains the same as the last normal intermediate value before the alarm. The alarm deactivation condition is: the intermediate values ​​calculated by three consecutive normal operations (leakage-free alarm trigger) are all within ±2% of a constant. At this time, the system automatically deactivates the alarm and resets the assumed leakage-free intermediate value to a constant.

[0119] This correction adaptively adjusts the total gas quantity parameter, ensuring that subsequent calculations are consistent with the current actual gas quantity, eliminating confirmed systematic biases, and improving long-term judgment stability.

[0120] Beneficial effects: The total gas volume baseline value is corrected based on the actual measurement results after each operation, which can offset the slight drift that occurs during long-term operation and keep the monitoring system accurate over the long term.

[0121] The ratio of operating power consumption to contact displacement is used as an additional verification term to establish a second constant relationship that is parallel and independent of the physical relationship (1) and does not involve substitution in the calculation. The power consumption per unit displacement is denoted as... ,in To efficiently control power consumption, This represents the total displacement of the contact movement. The standard expression for the second constant relation is: (2); in, , where k is the absolute value of the pressure change, k2 is the proportionality coefficient, and b2 is the mechanical resistance reference power consumption. Equation (2) is obtained through factory testing and calibration. The calibration method is independent of Equation (1). During operation, only parallel verification is performed, and it is not substituted into the calculation of Equation (1). This verification item establishes a two-dimensional correlation between pressure and volume and between power consumption and displacement, forming a cross-validation mechanism to avoid the limitations of single-dimensional judgment.

[0122] Under normal airtight conditions, equation (2) holds true. This relationship is determined by the mechanical efficiency of the equipment and is calibrated through factory testing: under conditions of good airtightness and normal mechanical condition, collect no less than 50 sets of unit displacement power consumption w and pressure change ΔP under different pressures (0.4MPa to 0.8MPa) and different displacements (50% to 100% of rated displacement), and use the least squares method to linearly fit to obtain the proportional coefficient k2 and mechanical resistance reference power consumption b2 in equation (2); The proportional coefficient represents the change in power consumption caused by a unit pressure change, and is related to the air chamber volume and mechanical transmission ratio. The reference power consumption for mechanical resistance corresponds to the no-load power consumption when the pressure change is zero. The fitting correlation coefficient should be no less than 0.95.

[0123] If, during actual operation, the data point formed by the unit displacement power consumption and pressure change deviates from the straight line by more than ±5%, but the gas chamber pressure is at extremely low pressure (<0.3MPa) or high pressure (>0.9MPa), piecewise linear fitting is permitted: different proportional coefficients and mechanical resistance reference power consumption are calibrated in three intervals: 0.3MPa~0.5MPa, 0.5MPa~0.7MPa, and 0.7MPa~0.9MPa. During operation, the coefficients for the corresponding interval are automatically selected based on the current pressure. The main reason for nonlinear deviation is that the gas compressibility factor changes significantly under low pressure, and mechanical friction increases nonlinearly under high pressure. Piecewise linear fitting can effectively approximate the actual physical characteristics.

[0124] This second constant relationship establishes a quantitative correlation between mechanical properties and airtightness, providing a core basis for distinguishing between changes in gas composition and leakage, and between leakage and mechanical failure, thus solving the technical pain point that traditional methods cannot distinguish between such complex or non-leakage anomalies.

[0125] Beneficial effects: When the equipment is operating normally, there is a stable correlation between power consumption and pressure changes. Using this as a benchmark, abnormal gas conditions and mechanical conditions can be accurately identified.

[0126] When the intermediate value M deviates from the constant but equation (2) still holds (the measured value w deviates from the theoretical value calculated according to equation (2) by ≤ ±5%), it is determined to be a change in gas composition rather than a leak.

[0127] It should be noted that a deviation of the intermediate value from the constant indicates an abnormality in the pressure-volume relationship, but the second constant relationship still holds (the deviation between actual unit displacement power consumption and theoretical value ≤ ±5%). This indicates that the correlation between unit displacement power consumption and pressure change conforms to normal patterns, meaning the chamber pressure resistance has not changed due to changes in the total gas volume. The abnormality is not due to gas leakage (leakage would reduce the total gas volume, decrease the pressure change, and simultaneously reduce unit displacement power consumption, breaking the second constant relationship), but rather due to changes in gas composition (such as SF6 gas purity decreasing to below 95%), which alters the gas constant in the gas state equation, causing the intermediate value to deviate. However, the correlation between pressure change and power consumption remains unaffected. In this case, a gas composition change alarm is output, not a leakage alarm, and there is no need to proceed with the leakage confirmation step.

[0128] This judgment rule can accurately distinguish between changes in gas composition and actual leaks, avoiding misjudging non-leaking gas quality issues as leak faults, reducing unnecessary operation and maintenance costs, and reminding operation and maintenance personnel to deal with abnormal gas composition in a timely manner to ensure the insulation performance of equipment.

[0129] The ingenuity of this invention lies in the fact that changes in gas composition only alter gas state parameters without changing the relationship between pressure resistance and power consumption; while leakage will simultaneously disrupt this relationship, thus allowing for accurate differentiation between the two types of anomalies.

[0130] When the intermediate value M deviates and equation (2) is broken simultaneously (the measured w deviates from the theoretical value calculated according to equation (2) by more than ±5%), it is determined to be a combined fault of leakage and mechanical failure, and the contribution of leakage and mechanical failure are estimated respectively. When the intermediate value deviates from the constant and the relationship between the power consumption per unit displacement and the pressure change exceeds the allowable error range (±5%), it indicates that there is both gas leakage and mechanical failure (such as mechanical jamming and increased friction).

[0131] The methods for estimating the contribution of leakage and mechanical failure are as follows: 1. Based on the second constant relationship, calculate the theoretical unit displacement power consumption under ideal mechanical fault-free conditions, which is the product of the proportional coefficient and the measured pressure change plus the mechanical resistance reference power consumption. 2. Calculate the difference between the actual power consumption and the theoretical power consumption. This difference is caused by mechanical failure (increased mechanical resistance). 3. Based on the ideal gas law, calculate the theoretical intermediate value under no-leakage conditions, which is the product of the theoretical pressure under no-leakage conditions and the actual volume of the gas chamber (the theoretical pressure under no-leakage conditions is derived by inversely from the second constant relationship). 4. Calculate the difference between the actual median value and the theoretical median value, which is caused by leakage; Since the dimension of the difference between the actual intermediate value and the theoretical intermediate value is energy, and the dimension of the difference between the actual power consumption and the theoretical power consumption is energy divided by length, the difference between the actual power consumption and the theoretical power consumption is multiplied by the total displacement of this normal operation and converted into the dimension of energy before comparison.

[0132] 5. The contribution of leakage is equal to the absolute value of the difference between the actual intermediate value and the theoretical intermediate value divided by the sum of the products of the absolute value of the difference between the actual intermediate value and the theoretical intermediate value, the absolute value of the difference between the actual power consumption and the theoretical power consumption, and the total displacement, and then multiplied by 100%. The contribution of mechanical failure is equal to the sum of the products of the products of the absolute value of the difference between the actual power consumption and the theoretical power consumption and the total displacement, divided by the sum of the products of the absolute value of the difference between the actual intermediate value and the theoretical intermediate value, the absolute value of the difference between the actual power consumption and the theoretical power consumption, and the total displacement, and then multiplied by 100%. The total displacement is the total displacement of this normal operation (in meters). The contribution calculation is accurate to one decimal place.

[0133] When the contribution of leakage exceeds 70%, the fault is determined to be primarily leakage; when the contribution of mechanical failure exceeds 70%, the fault is determined to be primarily mechanical failure; otherwise, it is determined to be a combined fault and handled equally. The contribution estimation results intuitively reflect the severity of the two types of faults, and output a combined alarm for leakage and mechanical failure without needing to proceed to the leakage confirmation step, providing maintenance personnel with a basis for fault priority judgment.

[0134] Beneficial effects: When leakage and mechanical failure occur simultaneously, by decomposing the degree of their respective impact on the actual value, it is possible to quantitatively determine which failure is dominant, providing a clear basis for on-site operation and maintenance.

[0135] After determining that there is a gas leak in the gas chamber, instead of immediately outputting a final alarm, the following confirmation steps are performed: After initially determining that there is a leak in the gas chamber, in order to eliminate the misjudgment caused by sensor transient failure (such as pressure acquisition jump caused by instantaneous electromagnetic interference) or external vibration interference (such as equipment being impacted during operation), a secondary verification is required through additional active control operations to ensure the accuracy of the leak determination.

[0136] It is understood that momentary interference only causes a single data anomaly and will not have a lasting impact on subsequent operations. By proactively adding a verification operation, momentary interference can be eliminated, avoiding false alarms caused by accidental jumps.

[0137] The active control switchgear performs an additional no-load operation, with the contact displacement set to be less than the normal operation displacement. The data processing unit sends an additional operation command to the switchgear's control circuit, including the operation type (no-load opening or closing, consistent with the previous normal operation type) and the displacement setpoint. The additional operation is triggered within 1 to 5 seconds after the initial leak detection, ensuring that the ambient temperature and gas state are essentially the same as the previous operation.

[0138] The additional contact displacement is set to 50% to 80% of the normal operating displacement (e.g., if the normal displacement is 100mm, the additional operating displacement is set to 60mm). This range ensures sufficient volume change to generate a detectable pressure change (additional operating pressure change ≥ 0.01MPa) while avoiding excessive mechanical wear due to excessive displacement. No-load operation ensures that there is no circuit switching load during operation, eliminating interference from load changes on parameters such as pressure and power consumption, and ensuring consistency of the comparison benchmark between two operations.

[0139] Specifically, using no-load operation can eliminate the influence of load changes on pressure. Shorter displacement can produce observable pressure changes while reducing the impact on the equipment. At the same time, execution within a short time can ensure that the operating conditions remain basically unchanged, improving the comparability of two operations.

[0140] The pressure change during the additional operation is collected and substituted into the same physical formula to obtain the second intermediate value. During the additional operation, the pressure change in the air chamber, the displacement of the contact (obtained through joint verification of the original current sensor and auxiliary contact), and the vibration signal are collected simultaneously. The same contact effective area correction logic as in normal operation is adopted (if the energy attenuation characteristics extracted from the vibration signal in the additional operation deviate from those in normal operation by ≤±10%, the corrected effective area of ​​normal operation is used). If the deviation is > ±10%, correct it again. In the physical formula, the absolute pressure of the air chamber is obtained by superimposing the static pressure and the pressure change (the static pressure acquisition stabilization time before additional operation is ≥ 5s). The actual volume of the gas chamber is obtained by superimposing the initial volume and the volume change caused by the contact movement. The volume change is equal to the product of the corrected effective contact area and the displacement. Substituting the additional operating pressure change and the additional operating displacement into the same physical relationship, the second intermediate value is calculated.

[0141] The two operations use the exact same calculation model and parameters to ensure the comparability of intermediate values ​​and avoid judgment errors caused by model differences.

[0142] The beneficial effect is that the two operations only change the operation displacement, which can ensure that the results only reflect the differences in gas state and are not affected by the calculation method.

[0143] Compare the deviations of the median values ​​during normal operation and additional operation. If the deviations are directly proportional to the displacement, a leak is confirmed; otherwise, it is considered a transient disturbance and the alarm is canceled. The median value during normal operation corresponds to the normal displacement; the median value during additional operation corresponds to the additional displacement.

[0144] Calculate the deviation range separately: the deviation range of normal operation is equal to the absolute value of the difference between the intermediate value of normal operation and the constant constant divided by the constant constant; the deviation range of extra operation is equal to the absolute value of the difference between the intermediate value of extra operation and the constant constant divided by the constant constant, where the constant constant is the reference value when the airtightness is normal.

[0145] If the ratio of the deviation of the additional operation to the deviation of the normal operation is equal to the ratio of the displacement of the additional operation to the displacement of the normal operation, and the error is within ±10%, then both anomalies are determined to be caused by leakage, and leakage is confirmed. This ±10% tolerance is determined as follows: Before the equipment leaves the factory, perform 30 normal and additional operations (displacement ratio of 0.6) under airtight conditions. Calculate the ratio of the deviation of the additional operation to the deviation of the normal operation for each operation, then divide this ratio by the ratio of the displacement of the additional operation to the displacement of the normal operation. Take the standard deviation of these ratios; the tolerance is then set to ±2 times the standard deviation (typically ±10%).

[0146] For different devices, the tolerance should be recalculated according to the above calibration process; if the proportional relationship is not met, it is determined to be a transient sensor failure or external vibration interference, and the leakage alarm should be canceled.

[0147] This confirmation step eliminates transient interference through proactive comparative experiments, minimizing the false alarm rate of leaks. It addresses the industry pain point that traditional monitoring methods are susceptible to transient interference, leading to false alarms, and further improves the reliability of leak detection.

[0148] Beneficial effects: In a real leak, the volume change is proportional to the displacement, and the deviation will also maintain a stable proportional relationship with the displacement; while instantaneous disturbances do not follow this physical law, so it is possible to reliably distinguish between real leaks and accidental disturbances.

[0149] The steady-state pressure and temperature change rates of the same gas chamber were collected between two consecutive switching operations. During the interval between two consecutive switching operations (interval ≥ 30s), the gas chamber entered a steady-state environment free from mechanical movement and strong electromagnetic interference. After each operation, the chamber was allowed to stabilize for at least 10 seconds before starting to collect steady-state pressure and temperature data, ensuring the absence of mechanical vibration and dynamic interference.

[0150] During this steady-state period, multiple sets of static pressure and temperature values ​​of the air chamber are continuously collected at fixed time intervals (1s / time), with ≥30 sets collected. After removing abnormal jump data (pressure jump > ±0.002MPa / time and temperature jump > ±0.5℃ / time are judged as abnormal and removed), the least squares method is used for linear fitting. The slope of the fitted line is the steady-state pressure change rate (unit Pa / min) and steady-state temperature change rate (unit K / min), which can truly reflect the slow change trend of air chamber pressure and temperature during non-operation phases and eliminate dynamic interference during operation.

[0151] This step can obtain the pressure and temperature change characteristics under steady-state conditions without increasing hardware costs, providing a reliable basis for subsequent fault identification and avoiding interference from dynamic process data in fault judgment.

[0152] Specifically, the dynamic process during switch operation introduces pressure fluctuations and vibration interference, while the steady-state data is more stable and can truly reflect long-term changes such as slow leakage and temperature drift, thus improving the accuracy of fault root cause identification.

[0153] The deviation of the steady-state pressure change rate from the median value is compared. The steady-state pressure change rate is normalized (the normalization formula is the measured pressure change rate minus the minimum value of the historical normal range, divided by the difference between the maximum and minimum values ​​of the historical normal range) so that its deviation from the median value has the same comparison benchmark (0-1 interval).

[0154] The direction of change of the steady-state pressure change rate and the direction of change of the deviation of the median value are determined separately as either increasing or decreasing. Simultaneously, the ratio of these two changes is calculated (this ratio equals the absolute value of the change in the normalized pressure change rate divided by the absolute value of the change in the deviation), providing a quantitative basis for subsequent correlation judgment. By jointly comparing the deviation of the median value obtained from dynamic operation with the steady-state pressure change rate, a preliminary distinction can be made between leakage anomalies and sensor malfunctions, avoiding misdiagnosis caused by relying on a single indicator.

[0155] Beneficial effects: By unifying the steady-state pressure change rate and the deviation of the dynamic intermediate value to the same benchmark for comparison, it is possible to more intuitively determine whether the two are caused by the same reason, thereby improving the accuracy of fault classification.

[0156] If the steady-state pressure change rate and the deviation from the median value both change in the same direction and their ratio falls within a certain range, then leakage is confirmed as the primary cause. "Same direction" means the steady-state pressure change rate is decreasing while the deviation from the median value is increasing, or both are increasing simultaneously.

[0157] The calibration range for the ratio of changes was determined through a combination of theoretical derivation and experimental verification. Theoretically, based on the ideal gas law... And laminar flow leakage flow equation, steady-state pressure change rate Rate of change of molar flow rate due to leakage Proportional; deviation of the median value With gas molar loss Proportional. Under constant temperature and low leakage conditions, the nominal value of the ratio of the steady-state pressure change rate to the deviation of the median value can be derived to be 1.0. Considering the error propagation of the gas chamber volume manufacturing tolerance (±5%), temperature measurement error (±0.5∘C), and pressure sensor accuracy (±0.2%FS), the theoretical range of ratio fluctuation is obtained by combining the root sum of squares method, which is 0.8~1.2.

[0158] Experimental Verification: Simulated leakage holes with different diameters (0.05mm~0.3mm) were machined on the gas chamber. At least 30 sets of experiments were conducted under rated pressure (0.4MPa~0.7MPa), rated temperature (25°C), and extreme temperature (-10°C~+50°C) conditions, accumulating at least 150 sets of experimental data. The ratio distribution of the changes was statistically analyzed. The ratio distribution range obtained from the experimental statistics should cover the theoretically derived range of 0.8~1.2, and the theoretical range should include the 95% confidence interval of the experimental statistics before it can be used as the judgment criterion. When the direction is consistent and the ratio falls within the 0.8~1.2 range, it indicates that the anomaly is caused by gas leakage in the gas chamber, ruling out sensor malfunction. This judgment rule can effectively identify the main cause of leakage, eliminate interference from temperature drift, sensor zero-point drift, etc., significantly improve the reliability of leakage judgment, and reduce false alarms caused by non-leakage factors.

[0159] Beneficial effects: Real leakage will simultaneously cause continuous changes in steady-state pressure and continuous deviations in dynamic median value. The trends of both changes are consistent and the ratio is stable, which can be clearly distinguished from other disturbances.

[0160] If the changes in the two values ​​are unrelated, the deviation of the steady-state temperature change rate from the median value is further compared. When the deviations of the steady-state temperature change rate and the median value are in opposite directions, it is determined to be a temperature sensor drift fault. An unrelated deviation between the steady-state pressure change rate and the median value means that the directions of change are irregular and the ratio of the changes exceeds the calibration range of 0.8-1.2, ruling out the possibility of a real leak. In this case, the steady-state temperature change rate is further introduced. If the steady-state temperature change rate shows an upward trend while the median value deviation shows a downward trend, or the steady-state temperature change rate shows a downward trend while the median value deviation shows an upward trend (i.e., opposite directions), it indicates that the temperature measurement value has deviated (drift > ±0.5℃), causing a systematic deviation in the median value calculation, and is determined to be a temperature sensor drift fault. By using the reverse change characteristics, temperature sensor drift can be accurately identified, effectively distinguishing between sensor faults and airtightness faults, and avoiding misjudging sensor faults as equipment leakage.

[0161] The innovation of this invention lies in the fact that when the temperature sensor drifts, the temperature measurement error will be transmitted in reverse to the intermediate value calculation, forming a reverse change characteristic. This feature can be used to directly identify temperature sensor abnormalities.

[0162] When there is no correlation between the steady-state temperature change rate and the deviation from the median value, it is determined to be a zero-point drift fault in the pressure sensor. "No correlation" means that the direction of change of the normalized steady-state temperature change rate and the direction of change of the median value deviation have no obvious pattern (approximately 50% probability of being in the same or opposite direction), and the ratio of their changes is consistently less than 0.5 or greater than 2.0. This judgment threshold (0.5 and 2.0) is derived from the statistical distribution of 50 sets of simulated pressure sensor zero-point drift experiments (drift range ±0.001MPa to ±0.005MPa) before shipment: 95% of the ratios of the changes fall within the union of 0 to 0.5 and 2.0 to infinity. This indicates that the pressure sensor zero point has shifted, causing the pressure acquisition value to continuously deviate from the true value, thus being determined as a zero-point drift fault in the pressure sensor. This rule can ultimately pinpoint the abnormality of the pressure sensor itself, achieving accurate classification of sensor faults and providing a clear target for subsequent self-calibration.

[0163] Beneficial effects: After eliminating leakage and temperature drift, the remaining systematic offset mainly comes from zero drift of the pressure sensor. Pressure sensor faults can be accurately located through non-correlated features.

[0164] Based on the judgment result, different alarm types are output, and the corresponding self-calibration process is initiated. If the main cause is confirmed to be leakage, a gas chamber leakage alarm (audible and visual alarm, alarm loudness ≥85dB, alarm light flashing frequency 1Hz) or a slow leakage warning (audible and visual alarm, alarm loudness ≥70dB, alarm light constantly on) is output. The self-calibration process maintains dynamic correction of the total gas quantity parameter without changing the sensor acquisition reference.

[0165] If the temperature sensor is determined to be drifting, a temperature sensor drift alarm is output. The self-calibration process automatically substitutes the current steady-state temperature value (determined by the average of multiple sets of collected data) into the calculation model to correct the temperature acquisition offset (the correction formula is that the corrected temperature equals the measured temperature minus the drift, where the drift is the temperature measurement offset). The corrected temperature and pressure values ​​directly replace the original collected values ​​and participate in subsequent intermediate value calculations and fault judgments to complete the self-calibration and restore the temperature measurement accuracy.

[0166] If the pressure sensor is determined to be a zero-point drift fault, a pressure sensor zero-point drift alarm will be output. The self-calibration process will recalibrate the pressure sensor zero point during the steady-state period (the calibration method is to collect the average of 30 sets of steady-state data as the new zero point, and the zero point error after calibration is ≤ ±0.0005MPa). The current steady-state pressure will be used as the reference value to correct the zero point offset, and the corrected value will be directly used in subsequent calculations.

[0167] If the problem is determined to be a change in gas composition, an abnormal gas composition alarm will be output, prompting maintenance personnel to perform gas testing and replacement; if the problem is determined to be a combined fault, a combined leak and mechanical fault alarm will be output, and the contribution of the leak and mechanical fault will be displayed simultaneously to guide maintenance priorities. If the verification process determines that the problem is a transient sensor fault or external vibration interference, an interference event record will be output without triggering an alarm. If the problem is determined to be a global calibration error, a calibration error alarm will be output to prompt maintenance personnel to calibrate the equipment.

[0168] Different alarm types make it easier for maintenance personnel to quickly locate the root cause of the fault. The corresponding self-calibration process can automatically repair sensor drift faults without stopping the system or disassembling the device, thereby improving the long-term stability and maintenance-free capability of the monitoring system.

[0169] Beneficial effects: The system can automatically output corresponding alarms according to the fault type and perform online self-calibration for sensor drift faults, restoring normal monitoring without manual intervention, thereby improving equipment availability and operation and maintenance efficiency.

[0170] The data processing unit employs a continuous multi-point judgment mechanism (an alarm is only output after three consecutive failure conditions are met). The final judgment result is output only when multiple consecutive sampling points meet the corresponding conditions, avoiding misjudgments caused by momentary interference. After an anomaly is determined, the system records event information (including occurrence time, fault type, relevant parameter values, calibration results, etc.), triggers a local audible and visual alarm, and uploads the anomaly type, trend, calibration parameters, contribution estimation results, confirmation step data, and bidirectional opening and closing verification data to the monitoring center (using Modbus TCP as the communication protocol, with a data transmission delay ≤1s).

[0171] For both opening and closing operations, the system employs a unified calculation logic, distinguishing only by displacement direction. The physical relationship automatically adapts to the direction of volume change, ensuring consistent judgment criteria for both operations. Each operation independently completes data acquisition, effective area correction, calculation of intermediate values ​​for opening and closing, deviation judgment, total gas volume correction, fault root cause differentiation, composite fault identification, and leakage confirmation (if necessary). Previous results do not affect subsequent calculations, ensuring monitoring independence and stability.

[0172] With multiple safeguards including external interference self-cancellation, dynamic correction of effective contact area, adaptive adjustment of total gas volume, self-identification and self-calibration of sensor faults, multi-chamber collaborative anti-global interference, quantitative differentiation of composite faults, secondary confirmation of leakage to resist transient interference, and bidirectional verification of opening and closing to cancel common interference, the intermediate value only truly reflects the change in total gas volume. The judgment result is not affected by factors such as temperature, speed, contact status, sensor drift, global interference, gas composition changes, mechanical faults, transient interference, and calibration errors. It can achieve high-precision online monitoring of multi-chamber equipment in a long-term stable manner.

[0173] This invention solves the problems of high false alarm rate, inability to distinguish abnormal types, inability to self-repair sensor faults, difficulty in eliminating global interference in multi-chamber equipment, easy confusion between gas composition changes and leaks, inability to identify composite faults, false alarms caused by transient interference, and the impact of common interference on single-direction monitoring by synchronously collecting multi-dimensional signals of displacement, pressure, vibration, temperature, and drive motor current. It combines a complete technical system including dual-source displacement fault tolerance calculation, dynamic correction of effective contact area, bidirectional verification to cancel common interference, classification of intermediate value deviation direction and amplitude, identification of slow leakage trend, adaptive correction of total gas volume, joint fault source differentiation based on steady-state pressure and temperature change rate, sensor drift self-calibration, multi-chamber collaborative anti-global interference, additional verification of operating power consumption and quantification of composite faults, and secondary confirmation of leakage to resist transient interference.

[0174] Specifically, the bidirectional verification of opening and closing circuit breakers collects bidirectional operation data and calculates the difference to offset common interferences such as operation speed fluctuations, ambient temperature changes, and sensor zero-point drift, while retaining only the differentiated signals caused by leakage, thus improving anti-interference capabilities. When the bidirectional median values ​​deviate synchronously but the difference is small, it is accurately determined to be a change in gas composition or a calibration error, avoiding misjudgment of non-leakage; for multi-chamber equipment, through independent acquisition and collaborative judgment, the precise separation of single-chamber leakage and global anomaly can be achieved; By introducing the ratio of operating power consumption to displacement as an additional verification item, a second constant relationship between mechanical characteristics and airtightness is established, which can accurately distinguish between changes in gas composition and actual leaks. The secondary leak confirmation step eliminates the influence of instantaneous electromagnetic interference and vibration shock through active no-load operation and proportional relationship verification, which greatly reduces the false alarm rate. By using steady-state pressure and temperature change rate, it can effectively distinguish between actual leaks and sensor drift, and supports online self-calibration without downtime maintenance. By comprehensively judging the direction, magnitude, and trend of deviation, multiple states such as leakage, slow leakage, blockage, excessive pressure, mechanical failure, and abnormal gas composition can be identified simultaneously, achieving multi-diagnosis with one machine.

[0175] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A leakage monitoring method for gas-insulated medium-voltage switchgear, characterized in that, include: During a single switching operation, the displacement of the contact and the change in air chamber pressure are collected simultaneously. An intermediate value is obtained by substituting the displacement of the contact movement and the pressure change into the inherent physical relationship of the equipment. The physical relationship is based on the gas chamber volume, the effective area of ​​the contact movement and the gas state equation, and is based on the ideal gas adiabatic process. When the deviation between the intermediate value and the constant determined by the physical parameters of the equipment exceeds the allowable range, it is determined that there is a gas leak in the gas chamber; Under normal airtight conditions, the deviation between the intermediate value and the constant does not exceed the allowable range; leakage reduces the total amount of gas in the chamber, causing the intermediate value to deviate from the constant beyond the normal fluctuation range; and the physical relationship ensures that the effects of operating speed fluctuations and ambient temperature changes on the displacement of the contact and the change in pressure cancel each other out when calculating the intermediate value.

2. The leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, The displacement of the contact movement is indirectly calculated by collecting multiple feature points in the waveform of the operating coil current and substituting them into the motion model. At the same time, the state sequence of the auxiliary contact is collected as a verification. When the alignment relationship between the current waveform feature points and the auxiliary contact state sequence on the time axis meets the matching condition, the current waveform calculation result is used. When the alignment relationship deviates, the system automatically switches to calculating the displacement based on the auxiliary contact state sequence and marks the current operation as a suspected mechanical wear event.

3. The leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, During a single switching operation, vibration signals from the contact movement process are simultaneously collected. The energy attenuation characteristics at the moment of collision between the moving contact and the stationary contact are extracted from the vibration signal. The energy attenuation characteristics are used to correct the effective contact area parameter in the physical relationship to compensate for the change in contact area caused by contact erosion or surface contamination. Among them, there is a pre-defined mapping relationship between the energy attenuation characteristics and the effective area of ​​the contact, and the corrected effective area is actually substituted into the physical relationship.

4. The leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, The direction and magnitude of the deviation of the intermediate value from the constant are handled separately: When the deviation direction is positive and the magnitude exceeds the first threshold, it is determined to be a gas chamber leak; When the deviation direction is negative and the magnitude exceeds the second threshold, it is determined that there is blockage in the air chamber or abnormally high pressure. When the deviation direction is positive but the magnitude does not exceed the first threshold, and the deviation magnitude of multiple consecutive operations shows an increasing trend, it is judged as a slow leak and an early warning is triggered. At the same time, the intermediate value of each operation is fed back to the gas state equation in the physical relation, and the total gas quantity parameter in the gas state equation is dynamically corrected to eliminate known deviations.

5. A leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, Collect the steady-state pressure change rate and steady-state temperature change rate of the same gas chamber between two adjacent switching operations; Compare the deviation of the steady-state pressure change rate from the median value: If the rate of change of steady-state pressure and the deviation of the median value change in the same direction and the ratio of their changes are within a certain range, then leakage is confirmed as the main cause. If the two changes are unrelated, then the deviation of the steady-state temperature change rate from the median value is further compared. When the deviation of the steady-state temperature change rate from the median value is in the opposite direction, it is determined to be a temperature sensor drift fault; when there is no correlation between the deviation of the steady-state temperature change rate from the median value, it is determined to be a pressure sensor zero-point drift fault. Based on the judgment result, different alarm types are output, and the corresponding self-calibration process is initiated.

6. A leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, For equipment containing multiple independent air chambers with different switching operating mechanisms, the displacement of the contact and the change in air chamber pressure are collected for each air chamber, and the intermediate value sequence of each air chamber is calculated by substituting them into the physical relationship formula. Calculate the average of the median values ​​for all chambers and the fluctuation range determined based on historical normal operating data, then compare the median value of each chamber with the average: When the median value of a certain air chamber exceeds the fluctuation range, while the median values ​​of other air chambers are all within the fluctuation range, the air chamber is determined to be leaking. When the median values ​​of multiple air chambers simultaneously exceed the fluctuation range in the same direction, it is determined that there is a global anomaly in the shared pressure source or ambient temperature. At this time, the air chamber with the smallest deviation is used as the reference benchmark, and the relative deviation of each air chamber is recalculated to eliminate global interference before making a judgment.

7. A leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, During a single switching operation, the current curve of the drive motor of the operating mechanism is simultaneously acquired, and the operating power consumption is extracted from the current curve. The ratio of operating power consumption to contact displacement is used as an additional verification term, and a second constant relationship is established in parallel with the physical relationship: Under normal airtight conditions, the ratio of operating power consumption to contact displacement and pressure change satisfy a linear or piecewise linear relationship obtained through experimental calibration, which is determined by the mechanical efficiency of the equipment. When the intermediate value deviates from the constant but the second constant relationship still holds, it is determined to be a change in gas composition rather than a leak. When the median value deviates and the second constant relationship is broken at the same time, it is determined to be a combined fault of leakage and mechanical failure, and the contribution of leakage and mechanical failure are estimated respectively.

8. A leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, The intermediate values ​​calculated for each switching operation are stored in chronological order to form a time series. A sliding window with a window length that is dynamically adjusted according to the number of operations is used to calculate the cumulative sum of the deviation of the intermediate value within the window in real time; When the accumulated value exceeds the control limit, a leakage alarm is triggered. At the same time, the intermediate value at the alarm time is used as a feedback signal to adjust the correction coefficient of the gas chamber volume parameter in the physical relationship. The intermediate value of subsequent normal operation returns to a constant, while the deviation caused by leakage is not compensated. The adjustment range of the correction coefficient is proportional to the alarm confidence level, and the adjustment process only takes effect after the alarm is cleared.

9. A leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, After determining that there is a gas leak in the gas chamber, instead of immediately issuing a final alarm, the following confirmation steps are performed: The active control switchgear performs an additional no-load operation, and the displacement of the contacts during the additional operation is set to be less than the normal operating displacement. The pressure change during the additional operation was collected and substituted into the same physical relationship to obtain the second intermediate value; Compare the deviation of the median value between the normal operation and the additional operation: if there is a predetermined proportional relationship between the two deviations and the respective operation displacement, which is proportional to the contact movement displacement, then leakage is confirmed; otherwise, it is determined to be a transient sensor fault or external vibration interference, and the alarm is canceled.

10. A leakage monitoring method for gas-insulated medium-voltage switchgear according to claim 1, characterized in that, During a single switch operation, the displacement of the contact and the change in air chamber pressure in both the opening and closing directions are collected simultaneously, and then substituted into the physical formulas to calculate the intermediate values ​​for opening and closing. Under normal airtight conditions, the intermediate value of the opening circuit breaker and the intermediate value of the closing circuit breaker are equal and both are constant. When the absolute difference between the intermediate value of the opening circuit breaker and the intermediate value of the closing circuit breaker exceeds the threshold, it is determined that there is a gas leak in the air chamber. The calculation of the absolute difference offsets the effects of operating speed fluctuations, ambient temperature changes, and sensor zero-point drift on a single intermediate value. These interference factors produce deviations in the same direction and with approximately the same magnitude for the opening and closing operations. Furthermore, when both the opening and closing intermediate values ​​deviate from a constant, but the difference between the opening and closing intermediate values ​​is still less than the threshold, it is determined to be a change in gas composition or a global calibration error rather than a leak.

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