A control method for triggering a circuit cut-off by water accumulation in a cable branch box

Abstract

The application provides a control method for triggering circuit cutting of water accumulation in a cable branch box, comprising the following steps: after the water risk reaches a preset limit, the water level reaching position is checked in the to-be-evaluated track section in sequence according to the sampling time sequence, and the sequence and the reaching time of the water level reaching the bottom of the fuse insulating cylinder, the lower edge of the bus insulating sheath in sequence along the lower edge of the insulating water barrier are recorded; when the water level reaching position advances in sequence along the lower edge of the insulating water barrier, the bottom of the fuse insulating cylinder and the lower edge of the bus insulating sheath and does not fall back below the lower edge of the insulating water barrier again, it is determined that the water level continuously approaches the key insulating position of the live component, and the continuously approaching period is taken as a determination triggering time window.

Description

Technical Field

[0001] This invention relates to the field of information technology, and in particular to a control method for cutting off a water accumulation trigger circuit in a cable branch box. Background Technology

[0002] The cable distribution box is constantly exposed to the outdoor environment, and factors such as rainwater seepage and groundwater backflow make water accumulation a frequent safety hazard, leading to short circuits in live terminals. Existing water accumulation monitoring solutions mostly use a fixed threshold trigger mechanism, where the circuit is cut off when the water level sensor detects that the water depth exceeds a preset value. However, these solutions assume the water surface remains static, ignoring the continuous swaying of the box caused by vehicle traffic vibrations, foundation settlement, or wind loads. This results in a discrepancy between the actual water contact risk and the average water level. When the box vibrates, the narrow opening of the stabilizing chamber restricts liquid flow, causing the liquid to sway naturally within the chamber walls. External vibrations trigger this inherent swaying pattern, transforming the previously stable water surface into a oscillating state with a stable period and decreasing amplitude. The water level exhibits dynamic fluctuations over time. In this situation, the average water depth, as a static parameter, cannot accurately reflect the instantaneous water contact risk at the cable distribution box terminals. For example, if the average water depth in a enclosure is five centimeters, which, according to traditional threshold settings, has not yet reached the warning line, vibration can cause the water surface to oscillate by three centimeters. At the peak of the oscillation, the water surface may momentarily exceed eight centimeters in height, briefly approaching or even touching a live terminal nine centimeters from the bottom, resulting in repeated instantaneous proximity water contact events. Conversely, if another enclosure has an average water depth of eight centimeters, but if there are baffles or flow guiding structures inside the enclosure to dampen the water, the oscillation amplitude is suppressed to within one centimeter, and the actual risk of water contact is lower than the former. Setting the threshold too high will cause delayed cut-off when the water surface oscillates and contacts the terminal at low water levels, while setting the threshold too low will cause malfunctions under stable conditions at high water levels. Therefore, how to distinguish between the steady-state depth characteristics and dynamic oscillation characteristics of water in a vibration disturbance environment, and how to capture the brief events of the water surface momentarily approaching the terminal, becomes a key issue in achieving accurate circuit protection. Summary of the Invention

[0003] This invention provides a control method for cutting off the water accumulation trigger circuit in a cable branch box, mainly including: S1. Obtain the vibration acceleration sequence, liquid level height sequence, and conduction state sequence of the humidity sensor in the stabilizing chamber; determine the trajectory interception starting point based on the vibration acceleration sequence and the conduction state sequence; generate the liquid surface oscillation trajectory based on the trajectory interception starting point, the vibration acceleration sequence, and the liquid level height sequence. S2. The liquid surface oscillation trajectory is subjected to noise reduction processing to obtain the second liquid surface oscillation trajectory, and the average water level height sequence and the instantaneous oscillation peak height sequence are separated from the second liquid surface oscillation trajectory. S3. Determine the water contact pulse according to the conduction state sequence, and extract the trajectory segment to be evaluated from the second liquid surface oscillation trajectory according to the water contact pulse; S4. If the average water level height sequence and the instantaneous swing peak height sequence corresponding to the trajectory segment to be evaluated meet the preset risk limit conditions, then output the water contact risk limit flag. S5. Based on the water contact risk boundary marker, determine the sequence of liquid surface contact points and the time of each contact within the trajectory segment to be evaluated; S6. Determine the trigger time window based on the order of occurrence and the times of each touch. S7. If the instantaneous swing peak height sequence meets the preset water contact event conditions within the determination trigger time window, a circuit cut-off command is generated.

[0004] Furthermore, step S1 includes: Perform root mean square extraction within a sliding window on the vibration acceleration sequence to obtain the vibration intensity sequence; If the vibration intensity sequence exceeds the preset excitation threshold and the conduction state sequence does not show a conduction level, it is determined that the inherent reciprocating swaying mode in the stabilizing chamber is excited. The trajectory interception starts from the point where a predetermined length of historical buffer segment is traced back from the moment when the inherent reciprocating shaking pattern is determined to be triggered. Starting from the starting point of the trajectory, the vibration acceleration value and liquid level height value at the same sampling time are matched point by point according to the timestamp to form the liquid surface oscillation trajectory with time as the horizontal axis, liquid level height as the vertical axis, and synchronous vibration acceleration as an auxiliary marker.

[0005] Furthermore, step S2 includes: Wavelet threshold denoising is performed on the liquid height component of the liquid surface oscillation trajectory. A preset wavelet basis is selected for multi-level decomposition. High-frequency noise components are removed from the detail coefficients according to the soft threshold rule to obtain the denoised second liquid surface oscillation trajectory. A moving average window with a length consistent with the inherent swaying period is used to slide along the time axis on the second liquid surface oscillation trajectory. The average liquid level height within the moving average window is obtained as the average water level height at the corresponding time, and the maximum liquid level height within the same period is obtained as the height of the instantaneous swing peak. The average water level height sequence and the instantaneous swing peak height sequence are separated based on the average water level height and the instantaneous swing peak height.

[0006] Furthermore, step S3 includes: The high-level period of the moisture-sensing electrode is continuously recorded. Each complete period from low level to high level and back to low level is taken as a water contact pulse. The duration of the water contact pulse and the interval between the start times of two adjacent water contact pulses are extracted. Compare the changing trends of the duration and the interval within the sliding observation window. If the duration increases monotonically and the interval decreases monotonically, it is determined that the water surface has repeatedly crossed the height of the moisture-sensing electrode with the swing peak and immersed into the area near the charged terminal. Record the earliest sampling time when the determination is made as the immersion start point. Using the immersion start point to the current sampling time as the time interval, a continuous segment corresponding to the time interval is cut out from the second liquid surface oscillation trajectory as the trajectory segment to be evaluated.

[0007] Furthermore, step S4 includes: The trajectory segment to be evaluated is obtained, and the preset orifice height of the drain hole at the bottom of the narrow-mouth stabilizing chamber and the preset lower edge height of the insulating water-blocking edge below the live terminal are read. The average water level height value corresponding to the current sampling time is taken from the average water level height sequence in the trajectory segment to be evaluated. If the average water level height value is continuously higher than the orifice height of the drain hole, it is determined that the drain hole has been submerged by the liquid surface and the drain hole submersion mark is set. After the flooding mark of the drainage hole is set, the instantaneous swing peak height value corresponding to the current period is taken from the instantaneous swing peak height sequence within the trajectory segment to be evaluated; If the height of the instantaneous swing peak is not less than the preset lower edge height, output a water contact risk limit sign.

[0008] Furthermore, step S5 includes: Obtain the trajectory segment to be evaluated after the water contact risk limit marker is set; Read the bottom height of the first insulating component and the bottom edge height of the second insulating component; The bottom height of the first insulating component, the lower edge height of the second insulating component, and the lower edge height of the predefined water-blocking component together constitute three preset part height sequences; The instantaneous swing peak height values ​​are taken one by one in the sampling time sequence within the instantaneous swing peak height sequence within the trajectory segment to be evaluated; By comparing the extracted instantaneous swing peak height value with the height sequence of the three preset locations, the liquid surface contact location at each sampling moment is obtained.

[0009] Furthermore, after obtaining the liquid surface contact area at each sampling time, it includes: Based on the liquid surface contact point at each sampling moment, the moment when the height of the instantaneous swing peak is first not less than the height of the lower edge of the water-blocking component is recorded as the first contact moment; The moment when the height of the instantaneous swing peak is first not less than the height of the bottom of the first insulating component is the second contact moment; The moment when the height of the instantaneous swing peak is first not less than the height of the lower edge of the second insulating component is the third contact moment; Arrange the liquid surface contact points in chronological order according to the first contact time, the second contact time, and the third contact time, to obtain the contact time of each contact point.

[0010] Furthermore, step S6 includes: Determine whether the first touch time, the second touch time, and the third touch time satisfy the sequential relationship that the first touch time is earlier than the second touch time and the second touch time is earlier than the third touch time; If the aforementioned sequential relationship is satisfied, a preliminary conclusion can be drawn that the liquid surface contact points have progressed sequentially in the order of the lower edge of the insulating water-blocking edge, the bottom of the fuse insulating cylinder, and the lower edge of the busbar insulating sheath. Under the premise that the preliminary conclusion is valid, check point by point in the instantaneous swing peak height sequence along the sampling time sequence starting from the first touch time; The instantaneous swing peak height value at each sampling point is compared with the lower edge height of the water-blocking component; If the height of all instantaneous swing peaks within the entire inspection range is not lower than the height of the lower edge of the water-blocking component, then it is confirmed that the liquid level has not fallen back during the advancement process. When both conditions are met simultaneously—that the liquid surface has advanced in the preset sequence and has not fallen back—it is determined that the liquid surface is continuously approaching the critical insulation part of the live component. Using the first touch time as the starting boundary and the current sampling time as the ending boundary, the continuous time period between the starting and ending boundaries is extracted as the continuous approximation period and registered as the determination trigger time window.

[0011] Furthermore, step S7 includes: Within the time span of the trigger time window, multiple instantaneous swing peak height values ​​are continuously extracted from the instantaneous swing peak height sequence according to the set sampling period. The height of the lower edge of the insulator at the root of the live terminal is read as a fixed limit pre-stored in the configuration area of ​​the acquisition terminal. Each instantaneous swing peak height value is compared with the fixed limit one by one. Sampling points with height values ​​not less than the fixed limit are marked as over-limit points, and sampling points with height values ​​less than the fixed limit are marked as non-over-limit points, thus obtaining a comparison sequence in which over-limit points and non-over-limit points are alternately distributed. On the comparison sequence, the time span of consecutive over-limit points is accumulated from the latest sampling point that jumps from the non-over-limit point to the over-limit point. When a non-over-limit point is encountered, the accumulated time is cleared to zero and the calculation starts again from the next jump point to obtain the current accumulated time when the height of the instantaneous swing peak continuously exceeds the fixed limit. If the current cumulative duration reaches the set duration threshold, it is confirmed as a real water contact event and the real water contact event flag is set.

[0012] Furthermore, after confirming it as a genuine water contact event and setting the genuine water contact event flag, the following steps are taken: Based on the setting of the actual water contact event flag, a circuit disconnection command carrying the power supply equipment identifier and the time of the actual water contact event is generated; The circuit disconnection command is sent to the circuit breaker, which then drives the disconnection mechanism corresponding to the power supply circuit of the live terminal in the cable branch box to complete the disconnection action of the power supply circuit.

[0013] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: This invention discloses a control method for cutting off a water-triggered circuit in a cable branch box. Addressing the problem of water swaying due to vibration in the stabilizing chamber of a cable branch box, gradually approaching live terminals and ultimately causing a short circuit, this invention simultaneously collects vibration acceleration and liquid level sequences at the bottom of the stabilizing chamber and at a rapid moisture-sensing electrode. Vibration exceeding a threshold is used as the trigger condition, and data acquisition is triggered before the moisture-sensing electrode is activated. After timestamp alignment, vibration and liquid level are correlated point-by-point to generate a liquid surface sway trajectory. After smoothing and noise reduction, the average water level and the instantaneous sway peak height are separated. When the duration of the moisture-sensing electrode activation increases and the water-touch pulse interval shortens, it is determined that the liquid surface has entered the vicinity of the live terminal, thereby determining whether the drain hole is submerged and the instantaneous sway peak height. The system checks whether the liquid level has reached the lower edge of the insulating water-blocking edge to indicate that the risk of water contact has reached a preset limit. It sequentially checks the points of contact with the liquid level, recording the order in which the liquid level reaches the bottom of the fuse insulation cylinder and the lower edge of the busbar insulation sheath, starting from the lower edge of the insulating water-blocking edge. When the liquid level advances in this order without receding, it is determined that the liquid level is continuously approaching the critical insulation part of the live component, and this time period is taken as the trigger time window. Within this window, multiple instantaneous swing peak heights are continuously extracted and compared with the height of the lower edge of the insulator at the root of the live terminal. When the duration exceeding this fixed limit reaches a set threshold, it is confirmed as a real water contact event, and a circuit disconnection command is generated and sent to the circuit breaker to execute the power supply circuit disconnection action. This invention achieves accurate identification and automatic disconnection protection against the risk of water contact caused by water accumulation and swinging within cable branch boxes, effectively preventing short circuit accidents caused by water contact. Attached Figure Description

[0014] Figure 1This is a flowchart of a control method for cutting off a water accumulation trigger circuit in a cable branch box according to the present invention.

[0015] Figure 2 This is a schematic diagram of a control method for cutting off a water accumulation trigger circuit in a cable branch box according to the present invention.

[0016] Figure 3 This is another schematic diagram of a control method for cutting off the water accumulation trigger circuit in a cable branch box according to the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0018] like Figures 1-3 The control method for cutting off the water accumulation trigger circuit in a cable branch box, as described in this embodiment, may specifically include: S101. Simultaneously collect vibration acceleration, liquid level sequence, and moisture sensing conduction status from the narrow liquid stabilization chamber below the live terminal of the cable branch box and the exposed rapid moisture sensing electrode. Use the vibration acceleration exceeding the preset excitation threshold as the trajectory interception start condition and trigger data acquisition before the moisture sensing electrode is turned on. After the timestamp is aligned, the vibration acceleration and liquid level are correlated point by point to generate the liquid surface oscillation trajectory.

[0019] A microelectromechanical vibration accelerometer is fixed to the inner wall of the narrow-mouth stabilizing chamber below the live terminals of the cable branch box. A pair of rapid humidity-sensing electrodes is arranged at the exposed position on the side wall of the stabilizing chamber. A capacitive liquid level sensor is installed at the top of the stabilizing chamber to continuously acquire the liquid level height sequence. The conduction state between the two poles of the humidity-sensing electrode pair is output in real time by a constant voltage excitation circuit. The three signals are uniformly connected to the acquisition channel with the same sampling clock source to obtain the original signal stream with timestamp alignment. The root mean square extraction within a sliding window is performed on the vibration acceleration component in the original signal stream to obtain a vibration intensity sequence reflecting the instantaneous strength of the disturbance. When the vibration intensity sequence exceeds the preset excitation threshold and the humidity-sensing electrode pair has not yet shown a conduction level, it is determined that the inherent reciprocating swaying mode in the narrow-mouth stabilizing chamber has been excited. A historical buffer segment of a preset length is traced back from this determination time as the starting anchor point for trajectory interception. Starting from the initial anchor point, the vibration acceleration value and liquid level height value at the same sampling time are paired point by point according to the timestamp to form a liquid surface oscillation trajectory with time as the horizontal axis, liquid level height as the vertical axis, and synchronous vibration acceleration as an auxiliary marker. The liquid surface oscillation trajectory retains the undulating shape of the water surface in the stable liquid chamber under disturbance and the disturbance intensity at the corresponding time, which is used to distinguish between the steady-state average water level and the instantaneous oscillation peak.

[0020] In one embodiment, the cable branch box is located at a ground substation next to an urban road or at a branch access point under an overhead line. The bottom of the box is equipped with the narrow-mouth liquid stabilizing chamber, which is a vertical cylindrical structure with an opening diameter to body diameter ratio of less than 0.6 and a body height of 150 mm to 250 mm. The live terminal is fixed directly above the liquid stabilizing chamber, and a fast-sensing moisture-sensing electrode pair is installed on the exposed side wall of the liquid stabilizing chamber. The centerline of the electrode pair is 30 mm to 50 mm lower than the root of the live terminal to ensure that the electrode contacts the water surface before the live terminal during the water level rise.

[0021] Specifically, a microelectromechanical vibration accelerometer is attached to the inner wall of the narrow-mouthed stabilizing chamber, which outputs the instantaneous value of the mechanical disturbance of the stabilizing chamber wall; a capacitive liquid level sensor is embedded in the top of the stabilizing chamber, which outputs an analog value of the liquid level height based on the principle that the dielectric constant between the plates changes with the water level; the moisture sensing electrode pair consists of two stainless steel needle-shaped electrodes, and a constant voltage excitation circuit applies a low-voltage DC between the two electrodes, outputting a high-level conduction signal when the water film connects the two electrodes.

[0022] Understandably, the three signals must share the same sampling clock source.

[0023] For example, a single high-precision analog-to-digital converter chip is used to simultaneously start three sampling channels with a sampling rate of 1000 Hz. Each sampling point is stamped with the same timestamp at the acquisition end. Timestamp alignment is completed through hardware synchronization to avoid phase drift caused by software scheduling.

[0024] It should be noted that the root mean square (RMS) extraction process of the vibration intensity sequence is as follows: A sliding window with a length of 256 sampling points is opened on the original vibration acceleration sequence. The window advances by 64 sampling points each time. Four operations are performed on the instantaneous acceleration value within the window: squaring, summing, dividing by the window length, and taking the square root, to obtain a root mean square value corresponding to that window. The continuously obtained RMS values ​​are arranged in chronological order to form the vibration intensity sequence. This sequence reflects the envelope shape of the instantaneous strength of the disturbance. Compared with directly comparing the original acceleration with the threshold, the RMS value suppresses the interference of single-point spike noise and better matches the continuous characteristics of the physical event of the inherent reciprocating sloshing within the steady fluid cavity being excited. The process for determining the preset excitation threshold is as follows: During the static calibration phase before the cable branch box is put into operation, a vibration intensity sequence under 30 minutes of no external disturbance is continuously collected. The mean of this sequence is taken as the static baseline and denoted as b. The magnitude of b depends on the ambient noise level, with a typical measured range of 0.03 to 0.08 meters per square second. For roadside boxes, boxes inside substation walls, and boxes inside underground utility tunnels, the b value will fall at different positions within this range due to differences in vibration caused by surrounding vehicle traffic. The preset excitation threshold is determined by k*b, with the multiplier k set to 3. The basis for this value is that an envelope of 3 times the standard deviation of the root mean square value within the calibration period can cover the natural fluctuations under undisturbed conditions. Exceeding this envelope indicates a significant external excitation. For example, if the measured value of b at a certain site is 0.05 m / s², then the threshold for that site is 0.15 m / s²; if the measured value of b at another site is 0.04 m / s², then the threshold is adjusted accordingly to 0.12 m / s². The threshold shifts along with the background environment of the enclosure, rather than taking a uniform fixed value across the entire network. When a certain root mean square value first exceeds the threshold corresponding to the local b, it is determined that the inherent sloshing mode of the narrow-mouth stabilizing chamber has been activated.

[0025] Preferably, the determination of excitation must be accompanied by a constraint, namely, that the moisture-sensing electrode pair has not yet reached a conduction level and is still in an open circuit state between the two electrodes. The significance of this constraint is that once the moisture-sensing electrode is turned on, it means that the water surface has risen to the electrode height. At this time, the water surface has entered the adjacent area close to the charged terminal, and trajectory interception must occur earlier than the conduction event in order to fully capture the entire process of the liquid surface transitioning from a smooth state to oscillation.

[0026] In one possible implementation, the acquisition end is equipped with a ring buffer that continuously stores the three synchronous sampling data from the most recent 2 seconds. The 2-second selection covers more than three times the typical inherent swaying period of the narrow-mouth steady liquid chamber (0.4 to 0.8 seconds), which is sufficient to completely preserve the steady-state segment before the disturbance is triggered. When both the triggering determination and the moisture sensing electrode being non-conductive are met simultaneously, the acquisition end traces back the complete 2-second historical buffer segment from the current moment as the starting anchor point. Thereafter, the liquid level height channel enters a continuous recording state until the end of the current event, thereby preserving the steady-state baseline segment before the disturbance and the oscillation response segment after the disturbance. Specifically, starting from the starting anchor point, the vibration acceleration value and liquid level height value at the same sampling moment are paired point by point according to the timestamp index. The horizontal axis is the time series, and the vertical axis is the liquid level height value. Each data point also carries the vibration acceleration at that moment as an auxiliary marker, thereby forming the liquid level oscillation trajectory. This trajectory preserves the reciprocating undulation shape of the water surface and the corresponding disturbance intensity, allowing for subsequent differentiation between the steady-state average water level and the instantaneous oscillation peak.

[0027] S102. Perform smoothing and noise reduction processing on the liquid surface oscillation trajectory to remove high-frequency interference components, separate the average water level height and the instantaneous oscillation peak height, and determine that the liquid surface is immersed in the area near the charged terminal when the duration of conduction of the moisture sensing electrode increases and the interval between adjacent water contact pulses shortens, and extract the trajectory segment to be evaluated from the determination time to the current sampling time.

[0028] Wavelet threshold denoising is performed on the liquid height component of the liquid surface oscillation trajectory. A three-level decomposition is performed using the db4 wavelet basis. High-frequency noise components are removed from the detail coefficients according to the soft threshold rule to obtain the denoised second liquid surface oscillation trajectory. A moving average window with a length equal to the inherent oscillation period is slid along the time axis on the second liquid surface oscillation trajectory. The average liquid height within the window is taken as the average water level height at that moment, and the maximum liquid height within the same period is taken as the instantaneous oscillation peak height. In this way, the average water level height sequence and the instantaneous oscillation peak height sequence are separated. Simultaneously with the generation of the average water level height sequence and the instantaneous swing peak height sequence, the high-level periods of the moisture-sensing electrode are continuously recorded. Each complete period of transition from low to high level and back to low level is considered a water-contact pulse. The duration of this pulse and the interval between the start times of two adjacent water-contact pulses are extracted. The changing trends of the duration and the interval are compared within a sliding observation window. If the duration monotonically increases and the interval monotonically decreases, it is determined that the water surface has repeatedly crossed the height of the moisture-sensing electrode with the swing peak and immersed into the vicinity of the charged terminal. The earliest sampling time at which the determination is made is recorded as the immersion start point. Using the immersion start point as the left end and the current sampling time as the right end, a continuous segment corresponding to this time interval is cut from the second liquid surface swing trajectory as the trajectory segment to be evaluated. The trajectory segment to be evaluated simultaneously carries the average water level height sequence, the instantaneous swing peak height sequence, and the duration and interval of the water-contact pulse within the corresponding interval.

[0029] In one embodiment, the liquid surface oscillation trajectory is a continuous sequence of liquid level height fluctuations over time within a narrow-mouthed stabilizing chamber, accompanied by vibration acceleration markers. The liquid level height component is mixed with electrical noise from the capacitive liquid level sensor, high-frequency disturbances caused by microscopic ripples on the water surface, and quantization noise from the acquisition channel. If directly used to separate the average water level from the instantaneous oscillation peak, it will lead to overestimation of the peak and fluctuations in the water level baseline. Therefore, smoothing and noise reduction must be performed first.

[0030] Specifically, the db4 wavelet basis is selected to perform wavelet threshold noise reduction on the liquid height component of the liquid surface oscillation trajectory. The db4 wavelet basis belongs to the Daubechies compactly supported orthogonal wavelet family, and its filter length is 8. It has good sparse representation ability for signals with an approximately sinusoidal shape and a slowly varying baseline, such as the reciprocating oscillation of the water surface. The signal energy is concentrated in the low-level approximation coefficients, while high-frequency noise is scattered in the detail coefficients.

[0031] It should be noted that the three-layer decomposition process is as follows: The liquid level height sequence is used as the approximation coefficient of the 0th layer. After convolution with the db4 decomposition low-pass filter and high-pass filter respectively, and then downsampled by 2 times, the approximation coefficients and detail coefficients of the 1st layer are obtained. The above convolution and downsampling are repeated on the approximation coefficients of the 1st layer to obtain the approximation coefficients and detail coefficients of the 2nd layer. The same operation is performed on the approximation coefficients of the 2nd layer for the third time to obtain the approximation coefficients and detail coefficients of the 3rd layer. After decomposition, the approximation coefficients of the 3rd layer carry the baseline information of the gradually changing liquid level, and the detail coefficients of the three layers carry the fluctuations and noise of different frequency bands. Soft thresholding is performed on the detail coefficients of the three layers layer by layer. The threshold determination process is as follows: Take the median of the absolute value of the detail coefficients of the layer, divide it by 0.6745 to obtain the noise standard deviation estimate of the layer, denoted as σ; let the total number of detail coefficients of the layer be N, and the soft threshold of the layer be... Where sqrt represents the square root operation and ln represents the natural logarithm operation. Detail coefficients with absolute values ​​less than t are set to zero, while those with absolute values ​​not less than t are processed according to the sign function and amplitude contraction rule, i.e., the output is equal to the difference between the original detail coefficient's sign multiplied by its absolute value minus t. The contracted detail coefficients and the third-layer approximation coefficients are then reconstructed layer by layer using a db4 reconstruction filter to obtain the noise-reduced second liquid surface oscillation trajectory. Preferably, the inherent oscillation period is determined by performing a fast Fourier transform on the vibration acceleration sequence immediately after the excitation determination in the previous stage, taking the reciprocal of the frequency corresponding to the maximum amplitude peak; a typical value falls between 0.4 seconds and 0.8 seconds. A moving average window with a length equal to the inherent oscillation period is opened on the second liquid surface oscillation trajectory. The window slides successively along the time axis in steps of a single sampling point. The arithmetic mean of the liquid surface height within each step of the window is taken as the average water level height at the center of the window. The maximum value of the liquid surface height within the same window is taken as the instantaneous oscillation peak height of that period, thus obtaining the average water level height sequence and the instantaneous oscillation peak height sequence. Further, edge detection is performed synchronously on the output level sequence of the moisture-sensing electrode. The rising edge from low level to high level is taken as the start of the water-contact pulse, and the falling edge from high level to low level is taken as the end of the water-contact pulse. The time difference between the start and end points is recorded as the duration of the pulse, and the time difference between the start points of two adjacent water-contact pulses is recorded as the pulse interval, thus obtaining the duration sequence and the pulse interval sequence. Specifically, the length of the sliding observation window is set to 5 consecutive water-contact pulses. No water-contact pulse is generated when the water surface has not yet surpassed the height of the moisture-sensing electrode. Water-contact pulses begin to appear when the water surface repeatedly surpasses the height of the moisture-sensing electrode due to the oscillating peak. As the average water level rises, the duration of the peak passing over the electrode increases, while the duration of the peak falling back below the electrode decreases. Linear regression is performed on the duration sequence of the 5 consecutive pulses within the sliding observation window, with the regression slope in seconds per pulse number. If the slope is positive and greater than 0.02, the duration is considered to be monotonically increasing. Simultaneously, the same linear regression is performed on the pulse interval sequence of the 5 consecutive pulses. If the slope is negative and the absolute value is greater than 0.02, the interval is considered to be monotonically decreasing. When both the monotonically increasing duration and monotonically decreasing interval conditions are met simultaneously, it is determined that the water surface has repeatedly surpassed the height of the moisture-sensing electrode with the oscillating peak and has immersed itself in the area adjacent to the charged terminal. The starting time of the first water-contact pulse within the sliding observation window is recorded as the immersion start point.

[0032] In one possible implementation, the immersion starting point is taken as the left end of the trajectory interception, and the current sampling time is taken as the right end of the trajectory interception. A continuous segment corresponding to the time interval is cut out from the second liquid surface swing trajectory as the trajectory segment to be evaluated. The trajectory segment to be evaluated simultaneously carries the average water level height sequence, the instantaneous swing peak height sequence, and the duration sequence and pulse interval sequence of the water contact pulse within the corresponding interval, recording the dynamic morphology after the water surface is immersed in the area adjacent to the charged terminal.

[0033] S103. Within the trajectory segment to be evaluated, determine whether the drain hole at the bottom of the stabilizing chamber is submerged by the liquid surface, and determine whether the height of the instantaneous swing peak has touched the lower edge of the insulating water-blocking edge below the live terminal. When the drain hole is submerged and the height of the instantaneous swing peak touches the lower edge of the insulating water-blocking edge, mark that the risk of water contact has reached the preset limit.

[0034] The trajectory segment to be evaluated is acquired, and the preset orifice height of the drain hole at the bottom of the narrow-mouth stabilizing chamber and the preset lower edge height of the insulating water-blocking edge below the live terminal are read. The average water level height value corresponding to the current sampling time is taken from the average water level height sequence within the trajectory segment to be evaluated. If the average water level height value is continuously higher than the orifice height of the drain hole, it is determined that the drain hole has been submerged by the liquid surface, and a drain hole submersion flag is set. After the drain hole submersion flag is set, the instantaneous swing peak height value corresponding to the current cycle is taken from the instantaneous swing peak height sequence within the trajectory segment to be evaluated and compared with the lower edge height of the insulating water-blocking edge. If the instantaneous swing peak height value touches the lower edge of the insulating water-blocking edge, the water contact risk is marked as reaching a preset limit, and a water contact risk limit flag is output.

[0035] In one embodiment, the trajectory segment to be evaluated simultaneously carries the average water level height sequence and the instantaneous swing peak height sequence within the corresponding interval. A drain hole is provided at the bottom of the narrow-mouthed stabilizing chamber. The height of the drain hole opening is denoted as h1, based on the bottom surface of the stabilizing chamber. This height is marked according to the mechanical drawings and pre-stored in the configuration area of ​​the acquisition terminal when the cable branch box leaves the factory. An insulating water-blocking edge is provided below the live terminals. The height of the lower edge of the insulating water-blocking edge is denoted as h2, based on the same bottom surface, and is also pre-stored in the configuration area.

[0036] Specifically, the average water level height value corresponding to the current sampling time is taken from the average water level height sequence within the trajectory segment to be evaluated, and denoted as H1. H1 is continuously compared with the orifice height h1. The comparison is based on the moving average window. When H1 in three consecutive moving average windows satisfies H1>h1, it is determined that the drain hole has been submerged by the liquid surface, and the drain hole submersion mark is set. The three moving average windows correspond to a time span of 1.2 seconds to 2.4 seconds. This time span covers more than three times the inherent sloshing period of the narrow-mouth liquid stabilizing chamber, so that the setting result reflects that the water level is in a continuous submerged state rather than the residual high-frequency fluctuations of a single window. After the flooding mark of the drain hole is set, the instantaneous swing peak height value corresponding to the current cycle is taken from the instantaneous swing peak height sequence in the trajectory segment to be evaluated, and recorded as H2. H2 is compared with the lower edge height h2. If H2>=h2, it is determined that the instantaneous swing peak height has touched the lower edge of the insulating water-blocking edge. The water contact risk is marked as reaching the preset limit and the water contact risk limit mark is output. The water contact risk limit mark is a limit judgment result that the water surface has risen to the vicinity of the live terminal.

[0037] S104. After the risk of water contact reaches the preset limit, check the liquid contact points one by one in the sampling sequence within the trajectory segment to be evaluated, and record the order in which the liquid surface touches the bottom of the fuse insulation cylinder and the bottom edge of the bus insulation sheath from the lower edge of the insulating water barrier, as well as the time of each contact.

[0038] After the water contact risk limit marker is set, the trajectory segment to be evaluated is obtained. The heights of two newly added preset locations—the bottom height of the fuse insulation cylinder and the lower edge height of the busbar insulation sheath—are read. These, along with the predefined lower edge height of the insulating water barrier, constitute a sequence of three preset location heights. The instantaneous swing peak height sequence within the trajectory segment to be evaluated is sampled sequentially according to the sampling time sequence and compared with the three preset location heights in ascending order to obtain the liquid surface contact location at each sampling moment. Based on the liquid surface contact location at each sampling moment, the moment when the instantaneous swing peak height is first not less than the lower edge height of the insulating water barrier is recorded as the first contact moment, the moment when it is first not less than the bottom height of the fuse insulation cylinder is recorded as the second contact moment, and the moment when it is first not less than the lower edge height of the busbar insulation sheath is recorded as the third contact moment. These three contact moments are then arranged according to their chronological order to obtain the sequence of liquid surface contact locations and their respective contact times.

[0039] In one embodiment, after the touch water risk limit flag is set, the instantaneous swing peak height sequence in the to-be-evaluated trajectory segment has completed the touch judgment of the lower edge of the insulating water retaining edge. A fuse and a busbar are sequentially arranged above the live terminal in the vertical direction, the fuse is externally sleeved with an insulating cylinder, and the bottom of the insulating cylinder faces downward and is exposed to the upper space in the liquid stabilizing chamber; the busbar is covered with an insulating sheath, and the lower edge of the sheath is located above the bottom of the insulating cylinder of the fuse. This height difference design is usually to ensure electrical insulation coordination or prevent liquid / condensation from dripping directly along the busbar sheath to the key part of the fuse, forming a stepped protection structure. The positional relationship among the lower edge of the insulating water retaining edge, the bottom of the insulating cylinder of the fuse, and the lower edge of the insulating sheath of the busbar is clearly fixed by the structural assembly drawing of the cable branch box. The bottom of the insulating cylinder of the fuse is located above the live terminal, and is vertically arranged at the lowermost end of the insulating cylinder sleeved outside the fuse. The bottom faces downward and is exposed to the upper space in the liquid stabilizing chamber. The lower edge of the busbar insulating sheath is the lowermost edge of the insulating sheath covering the busbar, and in the vertical direction, it is located above the fuse. The bottom (h3) of the fuse insulating cylinder is lower than the lower edge (h4) of the busbar insulating sheath. h2 is not obtained by on-site temporary measurement, but is a design parameter clearly fixed by the structural assembly drawing of the cable branch box, which is the theoretical design height of the lower edge of the specific structural member "insulating water retaining edge" inside the box relative to the common reference plane (the bottom surface of the liquid stabilizing chamber). In order to effectively protect the live components (fuse and busbar) above, the water retaining edge must be arranged at the lowermost position of all protected electrical components. Therefore, in the height sequence, it necessarily satisfies h2<h3 (lower than the fuse) and h2<h4 (lower than the busbar).

[0040] Specifically, taking the bottom surface of the liquid stabilizing chamber as a common reference, the height h2 of the lower edge of the insulating water retaining edge is 3mm above the static liquid level, that is, h2 serves as the minimum warning height at which the water surface starts to touch the internal insulating components; the height of the bottom of the fuse insulating cylinder is denoted as h3, the height of the lower edge of the busbar insulating sheath is denoted as h4, and h2<h3<h4, the three together form a preset part height sequence. Within the interval from ts to te, the instantaneous swing peak height H2 is read point by point according to the sampling time sequence, and is compared with h2, h3 and h4 in ascending order. The sampling time when H2 is not less than h2 for the first time is recorded as the first touch time t1, corresponding to the water surface touching the lower edge of the insulating water retaining edge; the sampling time when H2 is not less than h3 for the first time is recorded as the second touch time t2, corresponding to the water surface further rising to the bottom of the fuse insulating cylinder; the sampling time when H2 is not less than h4 for the first time is recorded as the third touch time t3, corresponding to the water surface rising to the lower edge of the busbar insulating sheath. t1, t2, and t3 extend sequentially on the time axis, reflecting the time sequence progression pattern of the water surface in the to-be-evaluated trajectory segment, starting from the lower edge of the insulating water retaining edge, and rising step by step to the bottom of the fuse insulating cylinder and the lower edge of the busbar insulating sheath. If a certain touch time is not recorded before te, it is recorded as empty, indicating that the corresponding part is not touched by the water surface in this trajectory segment.

[0041] S105. When the liquid surface touches the part in the order of the lower edge of the insulating water-blocking edge, the bottom of the fuse insulating cylinder, and the lower edge of the busbar insulating sheath, and does not fall back below the lower edge of the insulating water-blocking edge, it is determined that the liquid surface is continuously approaching the critical insulating part of the live component, and the continuous approaching period is taken as the triggering time window.

[0042] The system acquires the first, second, and third contact times and their sequential relationship, and determines whether the three contact times satisfy the sequential relationship that the first contact time is earlier than the second contact time and the second contact time is earlier than the third contact time. If the three do not satisfy the sequential relationship, it is considered that the liquid surface contact part has not advanced in the preset order and the current round of determination is terminated. If the three satisfy the sequential relationship, a preliminary conclusion is obtained that the liquid surface contact part has advanced in the order of the lower edge of the insulating water-blocking edge, the bottom of the fuse insulating cylinder, and the lower edge of the busbar insulating sheath. Under the premise that the preliminary conclusion is valid, starting from the first contact moment, the instantaneous swing peak height sequence is checked point by point along the sampling time sequence. The instantaneous swing peak height value of each sampling point is compared with the height of the lower edge of the insulating water barrier. If any sampling point in the inspection interval has an instantaneous swing peak height value lower than the height of the lower edge of the insulating water barrier, it is determined that the liquid level has fallen back below the lower edge of the insulating water barrier, and the preliminary conclusion is overturned. If all instantaneous swing peak height values ​​in the entire inspection interval are not lower than the height of the lower edge of the insulating water barrier, it is confirmed that the liquid level has not fallen back during the advancement process. When both conditions are met simultaneously that the liquid level has advanced in the preset sequence and has not fallen back, it is determined that the liquid level is continuously approaching the critical insulation part of the live component. The first contact moment is taken as the starting boundary and the current sampling moment is taken as the ending boundary. The continuous time period between the starting and ending boundaries is taken as the continuous approach period and registered as the determination trigger time window.

[0043] In one embodiment, the first contact time t1, the second contact time t2, and the third contact time t3, and their sequential relationship on the time axis, are obtained. These three contact times record the sampling times when the instantaneous swing peak height H2 is first not less than the height h2 of the lower edge of the insulating water-blocking edge, the first not less than the height h3 of the bottom of the fuse insulating cylinder, and the first not less than the height h4 of the lower edge of the busbar insulating sheath, respectively. Together, they constitute the advancement trace of the liquid surface contact location in the time dimension. This step performs two processing steps on the advancement trace: contact sequence determination and no-fallback verification, distinguishing the continuous approaching state from the instantaneous surge height to obtain the determination trigger time window. The contact sequence determination gives a preliminary conclusion as to whether the liquid surface rises sequentially according to the preset spatial levels, and the no-fallback verification gives a confirmation result as to whether the liquid surface remains above the lower edge of the insulating water-blocking edge after rising.

[0044] Specifically, the first touch moment t1, the second touch moment t2, and the third touch moment t3 are read, and it is judged whether the three satisfy the sequential relationship of t1<t2<t3, that is, the lower edge of the insulating water retaining rim is touched first, the bottom of the fuse insulating cylinder is touched second, and the lower edge of the busbar insulating sheath is touched last. The judgment of the sequential relationship is completed by direct numerical comparison of the sampling moments, without involving any weighting operation or probability assessment. If the three touch moments do not satisfy the sequential relationship of t1<t2<t3, it is regarded that the liquid level touching parts do not advance in the preset order, for example, t3 appears earlier than t2 or t1, the current round of judgment is terminated, and the acquisition end returns to the monitoring and waiting stage of the water touch risk limit flag. This stage is a steady-state stage where the acquisition end is located after completing initialization and self-inspection of the sampling channel. The acquisition end continuously reads the second liquid level swing trajectory at a fixed sampling period, and periodically calls the limit criterion module described in S104 to compare the current instantaneous swing peak height H2 with the lower edge height h2 of the insulating water retaining rim. Once a sampling point where H2>=h2 appears again, the water touch risk limit flag is set from 0 to 1, and the sequence verification process of this S105 is entered again. If the three satisfy the sequential relationship, a preliminary conclusion that the liquid level touching parts have sequentially advanced in the order of the lower edge of the insulating water retaining rim, the bottom of the fuse insulating cylinder, and the lower edge of the busbar insulating sheath is obtained, and the process enters the no-fallback verification stage. The no-fallback verification is used to identify whether the water level drops as a whole due to disturbance attenuation or re-exposure of the drain hole after the three parts are successively touched. If the fallback situation is not verified, a transient spike will be misjudged as a continuous approaching. On the premise that the preliminary conclusion is valid, starting from the first touch moment t1, point-by-point inspection is performed in the instantaneous swing peak height sequence along the sampling time sequence. The instantaneous swing peak height sequence is extracted on the second liquid level swing trajectory with the natural sloshing period as a window, and each sampling point corresponds to an instantaneous swing peak height value H2. Numerical comparison is performed between H2 of each sampling point in the interval from t1 to the current sampling moment and the lower edge height h2 of the insulating water retaining rim. The comparison rule is: if H2>=h2, mark the sampling point as an approaching holding point; if H2<h2, mark the sampling point as a fallback point. The verification process proceeds point by point until the entire interval is scanned or the first fallback point is encountered, and once any fallback point is found, the current verification is suspended. If any fallback point where H2<h2 appears in the inspection interval [t1, current sampling moment], it is determined that the liquid level has fallen back below the lower edge of the insulating water retaining rim, the preliminary conclusion is overturned and the current round of judgment is terminated, the water touch risk limit flag is reset synchronously, and the acquisition end returns to the previous stage to wait for a new set event to arrive.If H2 at all sampling points within the entire inspection interval [t1, current sampling time] remains H2>=h2, meaning the entire interval is continuously composed of approaching points, then it is confirmed that the liquid surface has not fallen back below the lower edge of the insulating water-blocking edge during the advancement process. This, together with the preliminary conclusion, constitutes the determination result that the liquid surface is continuously approaching the critical insulation parts of the live components. The critical insulation parts of the live components include the insulating water-blocking edge, the fuse insulation cylinder, and the busbar insulation sheath. When the determination result of continuous liquid surface approach is valid, the first contact time t1 is used as the starting boundary tstart, and the current sampling time is used as the ending boundary tend. The continuous time period corresponding to [tstart, tend] is extracted as the continuous approach time period, and this continuous approach time period is registered as the determination trigger time window W. The determination trigger time window W carries the complete swing response of the liquid surface from the first contact with the lower edge of the insulating water-blocking edge to the current time, forming the timing basis for further verification of the spatial relationship between the water surface and the live terminals.

[0045] S106. Within the trigger time window, extract multiple instantaneous swing peak heights continuously according to the set sampling period, and compare them one by one with the fixed limit of the lower edge height of the insulator at the root of the energized terminal. When the instantaneous swing peak height exceeds the fixed limit for a duration that reaches the set duration threshold, it is confirmed as a real water contact event and a circuit cut-off command is generated and sent to the circuit breaker to execute the disconnection action of the power supply circuit of the energized terminal in the cable branch box.

[0046] The determination trigger time window is obtained. Within the window time span, multiple instantaneous swing peak height values ​​are continuously extracted from the instantaneous swing peak height sequence according to a set sampling period. The fixed limit of the lower edge height of the insulator at the root of the live terminal, which is pre-stored in the configuration area of ​​the acquisition end, is read. Each instantaneous swing peak height value is compared with the fixed limit one by one. Sampling points with height values ​​not less than the fixed limit are marked as exceeding the limit points, and sampling points with height values ​​less than the fixed limit are marked as not exceeding the limit points, resulting in a comparison sequence in which exceeding and not exceeding the limit points are alternately distributed. On the comparison sequence, the time span of consecutive exceeding the limit points is accumulated from the latest sampling point that jumps from not exceeding the limit point to exceeding the limit point. When a not exceeding the limit point is encountered, the accumulated time is cleared to zero and the calculation starts again from the next jump point to obtain the current accumulated time when the instantaneous swing peak height continuously exceeds the fixed limit. The current accumulated time is compared with a set time threshold. If the current accumulated time reaches the set time threshold, it is confirmed as a real water contact event and the real water contact event flag is set. Based on the setting of the actual water contact event flag, a circuit disconnection command carrying the cable branch box identifier and the actual water contact event time is generated. The circuit disconnection command is sent to the circuit breaker device through the communication link of the acquisition end. The circuit breaker device drives the disconnection mechanism corresponding to the power supply circuit of the live terminal in the cable branch box to complete the disconnection action of the power supply circuit.

[0047] In one embodiment, the determination trigger time window W is defined by the start boundary tstart and the end boundary tend. The instantaneous swing peak height sequence within the window has confirmed that the liquid surface is continuously approaching the critical insulation part of the energized component. This step uses this window as the working range to perform a final check on the spatial relationship between the water surface and the innermost insulation part of the energized terminal, and issues a circuit disconnection command after the check is passed.

[0048] Specifically, within the time span of the trigger time window W, the acquisition end continuously extracts multiple instantaneous swing peak height values ​​from the instantaneous swing peak height sequence according to a set sampling period Ts. The sampling period Ts ranges from 20 milliseconds to 50 milliseconds, which allows the acquisition end to obtain sufficiently dense sampling points within the window to capture the short spikes of the peaks. Further, a supporting insulator is fitted at the root of the live terminal. The supporting insulator undertakes the function of insulating the live terminal from the ground. The vertical height of its lower edge from the bottom surface of the stabilizing chamber is denoted as h5. h5 is the critical limit at which the water surface touches the insulating medium at the root of the live terminal after it is crossed. It is pre-stored in the configuration area of ​​the acquisition end and is called the fixed limit. According to the structural assembly relationship, h2 is less than h3, less than h5, and less than h4. That is, the lower edge of the supporting insulator is located above the bottom of the fuse insulating cylinder and below the lower edge of the busbar insulating sheath. Together with the heights in the previous step, they form a spatial hierarchy from bottom to top. Each instantaneous swing peak height value H2 is compared with the fixed limit h5 one by one. Sampling points with H2 greater than or equal to h5 are marked as exceeding the limit, and sampling points with H2 less than h5 are marked as not exceeding the limit. Exceeding and not exceeding the limit points are alternately distributed on the time axis according to the sampling time sequence to form a comparison sequence.

[0049] It should be noted that the calculation rule for the cumulative duration is as follows: The acquisition end is equipped with a cumulative duration counter C, initially set to zero. The comparison sequence is scanned along the sampling time sequence. When a sampling point that jumps from a non-exceeding point to an exceeding point is encountered, it is recorded as the cumulative starting point, and the counter C is reset. Accumulation begins for each sampling point, with the accumulated value of C equal to the sampling period Ts. When a non-exceeding point appears during the scan, it is determined that the continuous exceeding is interrupted. C is cleared to zero, and the system waits for the next sampling point that jumps from a non-exceeding point to an exceeding point as the new cumulative starting point. When continuous exceeding points occur without interruption, C continues to accumulate. The current value of C is the current cumulative duration for the instantaneous swing peak height to continuously exceed the fixed limit h5. Preferably, the current cumulative duration C is compared with a set duration threshold Tth, where Tth ranges from 800 milliseconds to 1500 milliseconds. This value ensures that Tth covers more than twice the inherent swaying period of the narrow-mouth stabilizing chamber (0.4 to 0.8 seconds), preventing occasional over-limit events caused by single spikes or individual adjacent peaks from being misjudged as continuous water contact. If C >= Tth, it is confirmed as a real water contact event, and the real water contact event flag Rflag is set. After the real water contact event flag Rflag is set, the acquisition terminal organizes a circuit disconnection command. This command carries the cable branch box identifier, the timestamp of the real water contact event, the start and end boundaries tstart and tend of the determination trigger time window W, and the trigger location identifier "lower edge of the insulator at the root of the live terminal". The circuit disconnection command is then sent to the circuit breaker device through the communication link between the acquisition terminal and the circuit breaker device. After receiving the circuit disconnection command, the circuit breaker device verifies whether the cable branch box identifier in the command matches its own. If they match, it drives the disconnection mechanism corresponding to the power supply circuit of the live terminal in the cable branch box to operate. The disconnection mechanism consists of a trip coil and a mechanical opening spring. After the trip coil is energized, it releases the mechanical opening spring, completing the disconnection of the power supply circuit and realizing the disconnection of the power supply circuit of the live terminal in the cable branch box.

[0050] The above description is merely a specific implementation of this specification. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the scope of protection of this specification is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this specification, and these modifications or substitutions should all be covered within the scope of protection of this specification.

Claims

1. A control method for cutting off a water accumulation trigger circuit in a cable branch box, characterized in that, The method includes: S1. Obtain the vibration acceleration sequence, liquid level height sequence, and conduction state sequence of the humidity sensor in the stabilizing chamber; determine the trajectory interception starting point based on the vibration acceleration sequence and the conduction state sequence; generate the liquid surface oscillation trajectory based on the trajectory interception starting point, the vibration acceleration sequence, and the liquid level height sequence. S2. The liquid surface oscillation trajectory is subjected to noise reduction processing to obtain the second liquid surface oscillation trajectory, and the average water level height sequence and the instantaneous oscillation peak height sequence are separated from the second liquid surface oscillation trajectory. S3. Determine the water contact pulse according to the conduction state sequence, and extract the trajectory segment to be evaluated from the second liquid surface oscillation trajectory according to the water contact pulse; S4. If the average water level height sequence and the instantaneous swing peak height sequence corresponding to the trajectory segment to be evaluated meet the preset risk limit conditions, then output the water contact risk limit flag. S5. Based on the water contact risk boundary marker, determine the sequence of liquid surface contact points and the time of each contact within the trajectory segment to be evaluated; S6. Determine the trigger time window based on the order of occurrence and the times of each touch. S7. If the instantaneous swing peak height sequence meets the preset water contact event conditions within the determination trigger time window, a circuit cut-off command is generated.

2. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 1, characterized in that, Step S1 includes: Perform root mean square extraction within a sliding window on the vibration acceleration sequence to obtain the vibration intensity sequence; If the vibration intensity sequence exceeds the preset excitation threshold and the conduction state sequence does not show a conduction level, it is determined that the inherent reciprocating swaying mode in the stabilizing chamber is excited. The trajectory interception starts from the point where a predetermined length of historical buffer segment is traced back from the moment when the inherent reciprocating shaking pattern is determined to be triggered. Starting from the starting point of the trajectory, the vibration acceleration value and liquid level height value at the same sampling time are matched point by point according to the timestamp to form the liquid surface oscillation trajectory with time as the horizontal axis, liquid level height as the vertical axis, and synchronous vibration acceleration as an auxiliary marker.

3. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 1, characterized in that, Step S2 includes: Wavelet threshold denoising is performed on the liquid height component of the liquid surface oscillation trajectory. A preset wavelet basis is selected for multi-level decomposition. High-frequency noise components are removed from the detail coefficients according to the soft threshold rule to obtain the denoised second liquid surface oscillation trajectory. A moving average window with a length consistent with the inherent swaying period is used to slide along the time axis on the second liquid surface oscillation trajectory. The average liquid level height within the moving average window is obtained as the average water level height at the corresponding time, and the maximum liquid level height within the same period is obtained as the height of the instantaneous swing peak. The average water level height sequence and the instantaneous swing peak height sequence are separated based on the average water level height and the instantaneous swing peak height.

4. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 3, characterized in that, Step S3 includes: The high-level period of the moisture-sensing electrode is continuously recorded. Each complete period from low level to high level and back to low level is taken as a water contact pulse. The duration of the water contact pulse and the interval between the start times of two adjacent water contact pulses are extracted. Compare the changing trends of the duration and the interval within the sliding observation window. If the duration increases monotonically and the interval decreases monotonically, it is determined that the water surface has repeatedly crossed the height of the moisture-sensing electrode with the swing peak and immersed into the area near the charged terminal. Record the earliest sampling time when the determination is made as the immersion start point. Using the immersion start point to the current sampling time as the time interval, a continuous segment corresponding to the time interval is cut out from the second liquid surface oscillation trajectory as the trajectory segment to be evaluated.

5. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 1, characterized in that, Step S4 includes: The trajectory segment to be evaluated is obtained, and the preset orifice height of the drain hole at the bottom of the narrow-mouth stabilizing chamber and the preset lower edge height of the insulating water-blocking edge below the live terminal are read. The average water level height value corresponding to the current sampling time is taken from the average water level height sequence in the trajectory segment to be evaluated. If the average water level height value is continuously higher than the orifice height of the drain hole, it is determined that the drain hole has been submerged by the liquid surface and the drain hole submersion mark is set. After the flooding mark of the drainage hole is set, the instantaneous swing peak height value corresponding to the current period is taken from the instantaneous swing peak height sequence within the trajectory segment to be evaluated; If the height of the instantaneous swing peak is not less than the preset lower edge height, output a water contact risk limit sign.

6. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 1, characterized in that, Step S5 includes: Obtain the trajectory segment to be evaluated after the water contact risk limit marker is set; Read the bottom height of the first insulating component and the bottom edge height of the second insulating component; The bottom height of the first insulating component, the lower edge height of the second insulating component, and the lower edge height of the predefined water-blocking component together constitute three preset part height sequences; The instantaneous swing peak height values ​​are taken one by one in the sampling time sequence within the instantaneous swing peak height sequence within the trajectory segment to be evaluated; By comparing the extracted instantaneous swing peak height value with the height sequence of the three preset locations, the liquid surface contact location at each sampling moment is obtained.

7. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 6, characterized in that, After obtaining the liquid surface contact area at each sampling time, the following is included: Based on the liquid surface contact point at each sampling moment, the moment when the height of the instantaneous swing peak is first not less than the height of the lower edge of the water-blocking component is recorded as the first contact moment; The moment when the height of the instantaneous swing peak is first not less than the height of the bottom of the first insulating component is the second contact moment; The moment when the height of the instantaneous swing peak is first not less than the height of the lower edge of the second insulating component is the third contact moment; Arrange the liquid surface contact points in chronological order according to the first contact time, the second contact time, and the third contact time, to obtain the contact time of each contact point.

8. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 1, characterized in that, Step S6 includes: Determine whether the first touch time, the second touch time, and the third touch time satisfy the sequential relationship that the first touch time is earlier than the second touch time and the second touch time is earlier than the third touch time; If the aforementioned sequential relationship is satisfied, a preliminary conclusion can be drawn that the liquid surface contact points have progressed sequentially in the order of the lower edge of the insulating water-blocking edge, the bottom of the fuse insulating cylinder, and the lower edge of the busbar insulating sheath. Under the premise that the preliminary conclusion is valid, check point by point in the instantaneous swing peak height sequence along the sampling time sequence starting from the first touch time; The instantaneous swing peak height value at each sampling point is compared with the lower edge height of the water-blocking component; If the height of all instantaneous swing peaks within the entire inspection range is not lower than the height of the lower edge of the water-blocking component, then it is confirmed that the liquid level has not fallen back during the advancement process. When both conditions are met simultaneously—that the liquid surface has advanced in the preset sequence and has not fallen back—it is determined that the liquid surface is continuously approaching the critical insulation part of the live component. Using the first touch time as the starting boundary and the current sampling time as the ending boundary, the continuous time period between the starting and ending boundaries is extracted as the continuous approximation period and registered as the determination trigger time window.

9. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 1, characterized in that, Step S7 includes: Within the time span of the trigger time window, multiple instantaneous swing peak height values ​​are continuously extracted from the instantaneous swing peak height sequence according to the set sampling period. The height of the lower edge of the insulator at the root of the live terminal is read as a fixed limit pre-stored in the configuration area of ​​the acquisition terminal. Each instantaneous swing peak height value is compared with the fixed limit one by one. Sampling points with height values ​​not less than the fixed limit are marked as over-limit points, and sampling points with height values ​​less than the fixed limit are marked as non-over-limit points, thus obtaining a comparison sequence in which over-limit points and non-over-limit points are alternately distributed. On the comparison sequence, the time span of consecutive over-limit points is accumulated from the latest sampling point that jumps from the non-over-limit point to the over-limit point. When a non-over-limit point is encountered, the accumulated time is cleared to zero and the calculation starts again from the next jump point to obtain the current accumulated time when the height of the instantaneous swing peak continuously exceeds the fixed limit. If the current cumulative duration reaches the set duration threshold, it is confirmed as a real water contact event and the real water contact event flag is set.

10. The control method for cutting off the water accumulation trigger circuit in a cable branch box according to claim 9, characterized in that, After confirming a real water contact event and setting the real water contact event flag, the following steps are taken: Based on the setting of the actual water contact event flag, a circuit disconnection command carrying the power supply equipment identifier and the time of the actual water contact event is generated; The circuit disconnection command is sent to the circuit breaker, which then drives the disconnection mechanism corresponding to the power supply circuit of the live terminal in the cable branch box to complete the disconnection action of the power supply circuit.

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