A monitoring and protection method based on the operating status of submersible pumps

Abstract

This invention discloses a monitoring and protection method based on the operating status of a submersible pump, relating to the field of submersible pump operation monitoring technology. The method includes: acquiring the water level, pump immersion depth, and outlet pipe height difference of the submersible pump's operating environment; calculating the static pressure reference pressure of the water column; collecting the outlet pressure change sequence during stable operation and performing periodic statistics to obtain an upper and lower static pressure threshold to determine the static pressure constraint zone; dividing the pressure into segments according to a predetermined pressure step size and establishing a pressure segment index space; and mapping the outlet pressure change sequence to a pressure segment index sequence to form an environmental constraint mapping structure. This invention calculates the static pressure reference pressure of the water column by acquiring the water level, pump immersion depth, and outlet pipe height difference, and performs periodic statistics based on the outlet pressure change sequence during stable operation to form an upper and lower static pressure threshold to determine the static pressure constraint zone. Simultaneously, it establishes a pressure segment index space and forms an environmental constraint mapping structure.

Description

Technical Field

[0001] This invention relates to the field of submersible pump operation monitoring technology, specifically a monitoring and protection method based on the operating status of a submersible pump. Background Technology

[0002] Submersible pumps typically operate using variable frequency speed control or switching modes in scenarios such as drainage, water intake, and pipeline transportation. The difference between the water level of the pump body, the immersion depth of the pump body, and the height of the outlet pipeline will cause the static pressure of the water column to change over time. In engineering applications, in order to achieve stable water supply and equipment safety, it is common practice to monitor the outlet pressure, motor current, speed, and flow rate, and take protective control measures such as speed reduction, power limiting, or shutdown when abnormal fluctuations are detected. In the actual operation of submersible pumps, idling, air intake, cavitation and backflow reversal are often accompanied by unstable outlet water pressure, flow rate and motor current. Since different states may show similar trends in external monitoring quantities, engineering usually combines multiple monitoring quantities for comprehensive judgment, and improves the reliability of identification by setting thresholds, time windows for statistics or comparing with stable operating conditions, so as to trigger corresponding protection and control in time at different operating stages. Meanwhile, the risk status of submersible pumps is not limited to the stable operation phase. The pressure decay process and pipeline water column backflow process during the shutdown phase may also introduce short-term backflow driving conditions, which may lead to impact risks during the restart phase. In order to improve the pertinence and consistency of protection and control, it is necessary to perform periodic analysis on the pressure change sequence under the constraints of the operating environment, and extract and correlate key features at different operating phases to support the identification and protection control of multiple risk statuses. Therefore, this invention proposes a monitoring and protection method based on the operating status of submersible pumps. Summary of the Invention

[0003] The purpose of this invention is to provide a monitoring and protection method based on the operating status of a submersible pump, so as to solve the problems mentioned in the background art.

[0004] This invention can be achieved through the following technical solution: a monitoring and protection method based on the operating status of a submersible pump, comprising: Step 1: Obtain the water level, pump body immersion depth, and outlet pipe height difference of the submersible pump's operating environment, and calculate the static pressure reference pressure of the water column; collect the outlet pressure change sequence during the stable operation phase and perform periodic statistics to obtain the upper and lower static pressure thresholds to determine the static pressure constraint zone; divide the pressure zone according to the predetermined pressure step size and establish a pressure zone index space, and map the outlet pressure change sequence to the pressure zone index sequence to form an environmental constraint mapping structure; Step 2: Monitor the changes in motor speed and motor current and determine the start time of the running event. Determine the start time of the changes in the sequence of changes in outlet water pressure and the sequence of changes in outlet water flow. Calculate the time difference between the two to form a response delay interval and map it to the pressure segment index space to obtain the inertial migration trajectory. Step 3: Set up at least two pressure measurement points in the outlet pipeline to obtain the pressure change curve. Identify the abnormal pressure propagation sections based on the fitting residual statistics and propagation time shift, and map them to the pressure section index space to form a propagation migration trajectory. Step 4: Monitor the pressure change curve during the submersible pump shutdown phase. When the pressure is higher than the upper limit threshold of static pressure and the duration reaches the pushback duration threshold, determine the water column pushback response zone and calculate the pushback area to form the shutdown pushback migration trajectory. Step 5: Perform correlation analysis on the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory within the pressure section index space to construct a risk status discrimination code. Based on the risk status discrimination code, identify the idling risk status, air intake risk status, cavitation risk status, and backflow reversal risk status, and execute the corresponding protection control.

[0005] A further technical improvement of the present invention is that the construction of the hydrostatic confinement region includes the following steps: During the stable operation phase, the water pressure change sequence is continuously collected at a preset operating cycle time, and the water pressure change sequence of each operating cycle is mapped to the pressure segment index sequence based on the pressure segment index space established in step one above. In each operating cycle, the monotonicity index, hysteresis area, and inflection point count of the pressure segment index sequence are calculated. When the monotonicity index meets the monotonicity judgment threshold, the hysteresis area meets the hysteresis area judgment threshold, and the inflection point count meets the inflection point judgment threshold, the operating cycle is determined to be a stable cycle and a set of stable cycles is formed. Within the set of stable cycles, the periodic pressure intervals of the corresponding stable cycles are constructed by using the pressure interval index sequence to cover the minimum pressure interval index and the maximum pressure interval index in the pressure interval index space, and the periodic pressure intervals of multiple stable cycles are superimposed to form an interval overlap distribution. The consistent pressure interval is determined by the set of continuous pressure segment indexes in the interval overlap distribution that reach the overlap determination threshold. The upper boundary of the consistent pressure interval is defined as the upper limit threshold of static pressure, and the lower boundary of the consistent pressure interval is defined as the lower limit threshold of static pressure. Thus, the static pressure constraint zone is determined by the pressure interval between the upper limit threshold of static pressure and the lower limit threshold of static pressure.

[0006] A further technical improvement of the present invention is that the division of the pressure segment index space in step one includes the following steps: Using the static pressure reference pressure of the water column as the reference center, the water pressure change sequence of multiple operating cycles is continuously collected within the static pressure constraint zone, and the frequency of pressure occurrence of the water pressure change sequence on the pressure axis is statistically analyzed to form a pressure distribution density curve. Based on the pressure distribution density curve, the position where the density change slope reaches the density slope judgment threshold is determined as the candidate pressure boundary point, and the candidate pressure boundary points are screened according to the pressure axis order to form a boundary point set; Multiple pressure zones are formed between adjacent boundary points, and the median pressure of the pressure zone is used as the representative pressure value of that pressure zone. Each pressure segment is sequentially numbered according to the pressure offset between the representative pressure value and the static pressure reference pressure of the water column to form a pressure segment index, and the pressure segment index and the operating cycle time are used to construct the pressure segment index space. During the operation of a submersible pump, when the sequence of changes in outlet water pressure is mapped to the pressure segment index space, the pressure segment is located by determining the pressure segment corresponding to the outlet water pressure value and outputting the corresponding pressure segment index.

[0007] A further technical improvement of the present invention lies in the following: the specific characteristics of the inertial migration trajectory in step two include the following steps: After determining the start time of the operating event, the start time of pressure change and the start time of flow change are determined according to the effluent pressure change sequence and the effluent flow rate change sequence, respectively, and the response delay interval is calculated. The time range between the start time of the running event and the start time of the flow rate change is defined as the inertial response observation segment, and the effluent pressure change sequence within the inertial response observation segment is mapped to the pressure segment index sequence based on the pressure segment index space established in step one. Within the inertial response observation segment, the first-order difference symbol sequence of the pressure segment index sequence is calculated, and the number of symbol changes is counted to determine the number of trajectory direction changes. At the same time, the hysteresis area and trajectory span of the pressure segment index sequence are calculated, where the trajectory span is the difference between the maximum pressure segment index and the minimum pressure segment index of the pressure segment index sequence. When the number of trajectory direction changes reaches the direction change determination threshold and the hysteresis loop area reaches the hysteresis area determination threshold, the inertial migration rate is determined by the ratio of the trajectory span to the response delay interval, and the inertial migration trajectory feature set is determined based on the inertial migration rate and the trajectory span.

[0008] A further technical improvement of the present invention lies in the following: the specific characteristics of the propagation migration trajectory formed in step three include the following steps: Set up at least two pressure measurement points on the water outlet pipe and obtain the pressure change curve within the same operating cycle; The abnormal pressure propagation section is determined based on the statistical value of the fitting residual, and the abnormal propagation operation cycle is determined based on the propagation time shift. The abnormal pressure propagation segments are mapped to the pressure segment index space to form a propagation migration trajectory; Within the same running cycle, the trajectory span metric of the propagation migration trajectory is calculated, where the trajectory span metric is the difference between the maximum pressure segment index and the minimum pressure segment index corresponding to the pressure propagation anomaly segment; The trajectory span growth and trajectory centroid shift are calculated between adjacent operating cycles, where the trajectory centroid shift is the cumulative difference of the pressure segment index centroid value corresponding to the pressure propagation anomaly segment in adjacent operating cycles. When the growth of the trajectory span reaches the expansion judgment threshold and the migration of the trajectory center of gravity reaches the center of gravity migration judgment threshold, it is determined that the abnormal pressure propagation segment has undergone directional expansion and formed a propagation migration trajectory feature set.

[0009] A further technical improvement of the present invention is that the specific characteristics of the shutdown backtracking migration trajectory obtained in step four include the following steps: After the submersible pump stops, the water pressure change sequence is continuously collected at a preset sampling period. The static pressure upper limit threshold is used as the back-pushing judgment benchmark to determine the segment of the water pressure change sequence. When the water pressure change sequence is continuously higher than the static pressure upper limit threshold and the duration reaches the back-pushing duration threshold, the water column back-pushing response zone is determined. The time accumulation of the portion of the water pressure value exceeding the upper limit threshold of static pressure within the water column back-pull response zone is calculated to determine the back-pull area. Based on the pressure segment index space, the sequence of water pressure changes within the water column back-pull response zone is mapped to the pressure segment index sequence. Within the water column back-pushing response zone, the first-order difference symbol sequence of the indexed sequence of the pressure section is calculated, and the number of consecutive fluctuation segments in the first-order difference symbol sequence of the index changing from positive to negative and then from negative to positive is determined as the number of index cycles. At the same time, the index centroid value of the indexed sequence of the pressure section within each index cycle is calculated, and the cumulative difference of the index centroid values ​​of adjacent index cycles is determined as the centroid migration amount. The proportion of sampling points in the first-order difference symbol sequence of the index that maintain the same symbol within each index cycle is determined as the directional consistency ratio. When the number of index loops reaches the loop count threshold, the centroid migration amount reaches the centroid migration threshold, and the direction consistency ratio reaches the direction consistency threshold, the set of shutdown pushback exception events is determined. Within the set of abnormal shutdown pushback events, the ratio of the pushback area to the duration of the water column pushback response zone is calculated to determine the pushback intensity coefficient. Based on the pushback intensity coefficient, the number of index cycles, and the center of gravity migration amount, a set of shutdown pushback migration trajectory features is formed.

[0010] A further technical improvement of the present invention lies in the following steps: Step five, the correlation analysis process, includes the following steps: Within the same operating cycle, obtain the time series index positions of the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory in the pressure section index space, and establish a time axis index based on the operating cycle time; The inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory are synchronously mapped according to the time axis index, forming a set of three types of migration trajectories in the time-pressure two-dimensional index space; In the trajectory set, identify the intersection segments of the inertial migration trajectory and the propagation migration trajectory within the same time axis interval where the corresponding pressure segment index is the same or adjacent, and identify the intersection segments of the propagation migration trajectory and the shutdown pushback migration trajectory within the same time axis interval where the corresponding pressure segment index is the same or adjacent. Calculate the duration and span of each trajectory intersection segment on the time axis, and determine the trajectory coupling segment when the duration of the trajectory intersection segment reaches the intersection time determination threshold and the trajectory span reaches the intersection trajectory span determination threshold. Risk status discrimination codes are constructed based on the trajectory coupling segments formed by the inertial migration trajectory, the propagation migration trajectory, and the shutdown backtracking migration trajectory.

[0011] A further technical improvement of the present invention is that step five includes: Within the same operating cycle, the index position sequences of the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory in the pressure section index space are obtained respectively; Within the pressure segment index space, determine the inertial trajectory segment corresponding to the inertial migration trajectory, the propagation trajectory segment corresponding to the propagation migration trajectory, and the backtracking trajectory segment corresponding to the shutdown backtracking migration trajectory, wherein each trajectory segment is determined by the maximum pressure segment index and the minimum pressure segment index of the corresponding migration trajectory; Calculate the segment overlap length between the inertial trajectory segment and the propagation trajectory segment, and calculate the segment overlap length between the propagation trajectory segment and the retrograde trajectory segment. At the same time, calculate the segment distance between the inertial trajectory segment and the retrograde trajectory segment. When the overlap length between the inertial trajectory segment and the propagation trajectory segment reaches the inertial propagation judgment threshold, but the overlap length between the propagation trajectory segment and the backtracking trajectory segment does not reach the propagation backtracking judgment threshold, it is determined to be an idling risk state. When the overlap length between the inertial trajectory segment and the propagation trajectory segment reaches the inertial propagation judgment threshold, and the overlap length between the propagation trajectory segment and the retrospective trajectory segment reaches the propagation retrospective judgment threshold, it is determined to be an air intake risk state. When the growth of the trajectory span of the propagation trajectory segment reaches the expansion judgment threshold and the segment distance reaches the distance judgment threshold, it is determined to be a cavitation risk state; when the trajectory span of the backtracking trajectory segment reaches the backtracking segment judgment threshold, it is determined to be a backflow reversal risk state.

[0012] Compared with the prior art, the present invention has the following beneficial effects: This invention calculates the static pressure reference pressure of the water column by obtaining the water level height, pump body immersion depth and outlet pipe height difference, and performs periodic statistics based on the outlet pressure change sequence during stable operation to form an upper and lower static pressure threshold to determine the static pressure constraint zone. At the same time, it establishes a pressure segment index space and forms an environmental constraint mapping structure, so that subsequent monitoring and judgment are carried out under clear operating environment constraints, reducing judgment drift caused by changes in operating conditions. Furthermore, during the operation phase, this invention calculates the response delay interval and forms an inertial migration trajectory by using the start time of the operation event, the start time of the effluent pressure change sequence, and the start time of the effluent flow change sequence. In the effluent pipeline, it identifies abnormal pressure propagation sections by using the fitted residual statistics and propagation time shift at at least two pressure measurement points and forms a propagation migration trajectory, thus achieving parallel characterization of the water body's inertial response and pressure propagation behavior. During the shutdown phase, it identifies the water column backtracking response zone based on the upper limit threshold of static pressure and calculates the backtracking area to form a shutdown backtracking migration trajectory, enabling the backtracking risk during the shutdown phase to be included in the same analytical framework. On the other hand, this invention performs correlation analysis on the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory within the pressure section index space, constructs a risk state discrimination code, and identifies idling risk state, air intake risk state, cavitation risk state, and backflow reversal risk state, and executes corresponding protection control, so that different risk states can be matched with differentiated protection control actions, improving the pertinence and consistency of protection control, and enhancing the coverage of shutdown and restart-related risks. Attached Figure Description

[0013] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0015] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0016] Please see Figure 1 As shown, the present invention provides a monitoring and protection method based on the operating status of a submersible pump, comprising: Step 1: Obtain the water level, pump immersion depth, and outlet pipe height difference of the submersible pump's operating environment; calculate the static pressure reference pressure of the water column. Collect the outlet pressure change sequence during stable operation and perform periodic statistics to obtain the upper and lower static pressure thresholds to determine the static pressure constraint zone. Divide the pressure zone into segments according to a predetermined pressure step size and establish a pressure segment index space. Map the outlet pressure change sequence to a pressure segment index sequence to form an environmental constraint mapping structure. By obtaining the water level, pump immersion depth, and outlet pipe height difference of the submersible pump's operating environment and calculating the static pressure reference pressure of the water column, static pressure reference conditions for the submersible pump's operating conditions can be established, providing a unified reference for subsequent pressure change analysis. Based on the benchmark, by collecting the effluent pressure change sequence and performing periodic statistics during the stable operation phase, the pressure change range under stable operation conditions can be obtained under the condition of eliminating transient disturbances. Based on this, the upper and lower static pressure thresholds are obtained to form a static pressure constraint zone, so that the determination of the submersible pump's operating status is limited to a pressure range consistent with the operating environment. On this basis, pressure segments are divided according to a predetermined pressure step size, and a pressure segment index space is established. The effluent pressure change sequence is mapped to a pressure segment index sequence, thereby converting the continuous pressure change process into a discrete sequence with a clear segment index structure, so that subsequent operating status analysis can be processed in a unified pressure segment index space.

[0017] The pressure zone index space can be established based on the initial static pressure constraint zone and updated or converged after the consistent pressure zone is determined.

[0018] Specifically, in this embodiment, the static pressure reference point is taken as the water pressure benchmark corresponding to the location of the water pressure measuring point. Therefore, the liquid column height is taken as the difference between the water level and the height of the outlet pipe, i.e., liquid column height = 15.0 - 10.0 = 5.0 meters. Then, the static pressure benchmark pressure of the water column is ρgh = 1000 × 9.81 × 5.0 = 49.05 kPa. The pump body immersion depth is used as a geometric constraint parameter to characterize the submersible pump's submerged operation conditions and air intake risk assessment, and is not used as the liquid column height item in the calculation of the static pressure benchmark of the outlet pressure measuring point. After entering the stable operation stage, the outlet pressure change sequence is continuously collected with a preset operation cycle time of 30 seconds and a sampling cycle of 0.1 seconds, and the operation cycle is segmented. 60 operation cycles are continuously collected to obtain 60 periodic pressure curves. The maximum pressure and minimum pressure within each operation cycle are calculated for the pressure curve within the cycle, and the maximum pressure within the cycle is calculated for the 60 operation cycles. The 95th quantile of the pressure is used to obtain the upper limit threshold of static pressure, which is set at 56.0 kPa. The 5th quantile of the minimum pressure within 60 operating cycles is used to obtain the lower limit threshold of static pressure, which is set at 44.0 kPa. Thus, the static pressure constraint zone is determined to be from 44.0 kPa to 56.0 kPa based on the pressure range between the upper and lower limits of static pressure. At the same time, a predetermined pressure step size of 0.5 kPa is set, so that the static pressure constraint zone is divided into 24 continuous pressure segments on the pressure axis, and a pressure segment index space is established. The pressure segments are divided in a closed-open interval manner, so that the static pressure constraint zone [44.0 kPa, 56.0 kPa] corresponds to 24 pressure segments, and each pressure segment corresponds to a pressure segment index. Before the consistent pressure range is determined, any effluent pressure value can be located by the pressure segment index through the initial lower limit threshold of static pressure and the predetermined pressure step size, so as to form the basic index framework of the environmental constraint mapping structure.

[0019] During the stable operation phase, the effluent pressure change sequence is continuously collected over a preset operating cycle. Based on the pressure segment index space established in step one, the effluent pressure change sequence for each operating cycle is mapped to a pressure segment index sequence. Within each operating cycle, the monotonicity index, hysteresis area, and inflection point count of the pressure segment index sequence are calculated. When the monotonicity index meets the monotonicity threshold, the hysteresis area meets the hysteresis area threshold, and the inflection point count meets the inflection point threshold, the operating cycle is determined to be a stable cycle, forming a stable cycle set. Within the stable cycle set, the minimum and maximum pressure segment indices of the pressure segment index sequence in the pressure segment index space are used to construct the corresponding stable cycle's periodic pressure intervals. Multiple stable cycle periodic pressure intervals are superimposed to form an interval overlap distribution. The set of continuous pressure segment indices in the interval overlap distribution that reach the overlap threshold is used to determine the consistent pressure interval, and the pressure above the consistent pressure interval is determined. The upper limit of static pressure is defined as the upper limit threshold, and the lower limit of static pressure is defined as the lower limit threshold. The static pressure constraint zone is determined by the pressure interval between the upper and lower limits of static pressure. The effluent pressure change sequence of each operating cycle is mapped to a pressure segment index sequence according to a predetermined pressure step size. The monotonicity index is calculated by the consistency ratio of the first-order difference symbol of the pressure segment index sequence. That is, the proportion of sampling points whose first-order difference symbol is consistent with the dominant symbol of the cycle within an operating cycle is used as the monotonicity index, and the monotonicity judgment threshold is 0.85. The hysteresis area is calculated by the closed loop area of ​​the pressure segment index sequence on the time axis. Specifically, the forward and backward trajectories of the pressure segment index sequence are paired within the same operating cycle and accumulated using the trapezoidal method to obtain the hysteresis area, and the hysteresis area judgment threshold is 18.0 index seconds. Furthermore, the hysteresis area is defined as the closed area formed between the forward and reverse trajectories of the pressure segment index sequence on the time axis.

[0020] The inflection point count is calculated using the number of changes in the first-order difference sign of the pressure segment index sequence, with an inflection point threshold of 4. In 60 operating cycles, those cycles satisfying a monotonicity index of not less than 0.85, a hysteresis area of ​​not more than 18.0 index seconds, and an inflection point count of not more than 4 are identified as stable cycles and form a stable cycle set. In this embodiment, the stable cycle set contains 42 operating cycles. Within the stable cycle set, for each stable cycle, the minimum pressure segment index and the maximum pressure segment index of its pressure segment index sequence are extracted to construct the cycle pressure interval. For example, if a stable cycle has a minimum pressure segment index of 3 and a maximum pressure segment index of 19, then the cycle pressure interval for that stable cycle is from index 3 to index 19. The 42 stable cycles are then used to construct the cycle pressure interval. The overlapping of periodic pressure intervals forms an interval overlap distribution. The interval overlap is calculated by dividing the number of stable cycles covering the pressure interval index by the size of the stable cycle set, with an overlap threshold of 0.70. From the interval overlap distribution, a set of continuous pressure interval indexes with an overlap of not less than 0.70 is selected to determine the consistent pressure interval. In this embodiment, the consistent pressure interval covers indexes 1 to 20. The upper boundary of the consistent pressure interval is defined as the upper limit threshold of static pressure, i.e., 55.0 kPa, and the lower boundary of the consistent pressure interval is defined as the lower limit threshold of static pressure, i.e., 45.0 kPa. This forms a converged static pressure constraint region of 45.0 kPa to 55.0 kPa, ensuring that the static pressure constraint region comes from the consistent constraint of the stable cycle set rather than a single statistical result.

[0021] In this embodiment, the upper and lower limits of static pressure in steps two through five are the converged upper and lower limits of static pressure.

[0022] After the consistent pressure range is determined, the lower limit threshold of the static pressure after convergence is used as the positioning benchmark for the pressure segment index. The pressure segment index space is updated, and the updated index number is used as the unique index number caliber for steps two to five.

[0023] The division of the pressure zone index space includes the following steps: Using the hydrostatic reference pressure as the center, continuously collect the outlet pressure change sequence for multiple operating cycles within the hydrostatic constraint zone, and statistically analyze the frequency of pressure occurrence along the pressure axis to form a pressure distribution density curve; determine the positions where the density change slope reaches the density slope judgment threshold based on the pressure distribution density curve as candidate pressure boundary points, and filter the candidate pressure boundary points according to the pressure axis order to form a boundary point set; the boundary point set is used to determine the pressure change structural characteristics; and divide the hydrostatic constraint zone according to a predetermined pressure step size. The pressure range is defined, with the median pressure of the range serving as its representative pressure value. The pressure range index space includes the set of pressure range indices corresponding to the converged static pressure constraint region and the set of overflow pressure range indices above the upper limit of the static pressure threshold. The overflow pressure range indexes are continuously expanded above the upper limit of the static pressure threshold at the same predetermined pressure step size as the static pressure constraint region, and their index numbers are sequentially increased based on the maximum index of the converged static pressure constraint region. The upper limit of the overflow expansion can be preset to N pressure ranges above the upper limit of the static pressure threshold or the pressure range corresponding to the preset maximum measurable pressure Pmax.

[0024] The overflow pressure segment index set is used for pressure segment index mapping of the shutdown backtracking migration trajectory. During the operation of the submersible pump, when the outlet pressure change sequence is mapped to the pressure segment index space, the pressure segment is located by determining the pressure segment corresponding to the outlet pressure value and outputting the corresponding pressure segment index. Specifically, within the converged static pressure constraint zone of 45.0 kPa to 55.0 kPa, 42 stable cycles of outlet pressure change sequences are continuously collected. Pressure bins are used to statistically analyze the frequency of pressure occurrence, with a bin width of 0.2 kPa, to obtain the pressure distribution density curve. The density change slope is calculated by dividing the frequency difference between adjacent pressure bins by the bin width, with a density slope threshold of 0.12 kPa. Pressure positions with a density change slope not less than 0.12 kPa are selected as candidate pressure boundary points. To ensure the stability and feasibility of the boundary point set, candidate pressure boundary points are screened according to the pressure axis order. The screening rule is that the interval between adjacent boundary points is not less than 0.6 kPa and the candidate pressure boundary points are within... The proportion of occurrences in 42 stable cycles is not less than 0.60, ultimately forming a set of boundary points, for example, the boundary point set is 45.2 kPa, 46.0 kPa, 47.4 kPa, 49.0 kPa, 50.6 kPa, 52.0 kPa, 53.8 kPa, and 54.8 kPa. Within the static pressure constraint zone, multiple pressure segments are divided according to a predetermined pressure step, and the median pressure of each pressure segment is used as the representative pressure value of that segment. To ensure that the numbering caliber of the pressure segment index is consistent with the pressure segment index positioning formula used in steps two to five, this embodiment sequentially numbers the pressure segments within the static pressure constraint zone according to their pressure values ​​from low to high, defining the index of the lowest pressure segment as 1, and then incrementing the index of each adjacent pressure segment by 1, thus forming a monotonically increasing pressure segment index. The static pressure lower limit threshold and the predetermined pressure step are used as positioning benchmarks, ensuring that any effluent pressure value P can be determined through the pressure segment index = ... Complete the pressure segment index positioning; after constructing the pressure segment index and the operating cycle time into a pressure segment index space, locate any outlet pressure value to its corresponding pressure segment and output the corresponding pressure segment index during the operation of the submersible pump to complete the pressure segment positioning, so that the subsequent static pressure constraint zone construction, pressure segment index sequence mapping and stable cycle set screening all use the same pressure segment index space.

[0025] The above steps are described in a consistent manner within the same embodiment to ensure full disclosure and consistency of steps: First, the static pressure reference pressure of the water column is calculated based on the water level, pump body immersion depth, and height difference of the outlet pipe, and the static pressure constraint zone is initially determined. Then, within the static pressure constraint zone, a set of boundary points is formed based on the pressure distribution density curve to determine the structural characteristics of pressure changes. Within the static pressure constraint zone, pressure segments are divided according to a predetermined pressure step size to establish a pressure segment index space. Subsequently, the outlet pressure change sequence of each operating cycle is mapped to a pressure segment index sequence, and the monotonicity index, hysteresis area, and inflection point count are calculated to screen stable cycles. The set of pressure intervals is superimposed based on the periodic pressure intervals of the stable periodic set to form an interval overlap distribution to obtain a consistent pressure interval. The upper and lower pressure boundaries corresponding to the consistent pressure intervals are defined as the upper and lower static pressure thresholds, respectively, and the static pressure constraint zone is finally determined. Through the above sequential implementation, the determination of the static pressure constraint zone and the division of the pressure segment index space are mutually verified. The entire process is driven by the periodic data of the effluent pressure change sequence in the stable operation phase. It can be reproduced in the same embodiment using a consistent data source, the same pressure segment index space, and a unified threshold definition method.

[0026] Step 2: Monitor changes in motor speed and current to determine the start time of the operating event. Determine the start times of the changes in the outlet pressure and flow rates, calculate the time difference between them to form a response delay interval, and map it to the pressure segment index space to obtain the inertial migration trajectory. By monitoring changes in motor speed and current and determining the start time of the operating event, the starting point of the change in the submersible pump's operating conditions can be identified, providing a clear time reference for subsequent response analysis. By determining the start times of the changes in the outlet pressure and flow rates and calculating the time difference between them to form a response delay interval, the response process of the water body inertia and the pipeline system to the operating event can be reflected. Then, mapping the pressure change process corresponding to the response delay interval to the pressure segment index space, the inertial migration trajectory can be obtained, describing the migration behavior of pressure changes in the pressure segment index space, thus providing a basis for identifying the inertial response characteristics of the submersible pump under the action of the operating event.

[0027] Specifically, in actual implementation, changes in motor speed and motor current are collected using the same sampling period, set to 0.1s. The average value of motor speed and motor current within 5 seconds prior to the occurrence of the running event is used as the reference value. The judgment range for motor speed change is set to 100 r / min, and the judgment range for motor current change is set to 1.5A. When the change in motor speed relative to the reference value reaches 100 r / min and lasts for more than 0.5s, the first sampling moment that meets the condition is determined as the start time of the running event. Similarly, if the change in motor current relative to the reference value reaches 1.5A and lasts for more than 0.5s, the first sampling moment that meets the condition is also determined as the start time of the running event. For example, if the motor speed drops from 2850 r / min to 2730 r / min in a certain running cycle and lasts for 0.6s, the moment when this change begins and the judgment condition is met is determined as the start time of the running event, for example, 10:15:20.0. Subsequently, the effluent pressure change sequence and the effluent flow rate change sequence were monitored synchronously, and their starting change time was determined respectively. For example, the effluent pressure change sequence showed a significant change at 10:15:20.6, while the effluent flow rate change sequence showed a change at 10:15:22.1. The time difference between the two was 1.5s. This time difference was determined as the response delay interval and used as the time scale basis for inertial response analysis.

[0028] After determining the start time of the operational event, the initial pressure change time and the initial flow rate change time are determined based on the effluent pressure change sequence and the effluent flow rate change sequence, respectively, and the response delay interval is calculated. During implementation, the average effluent pressure within 3 seconds prior to the start time of the operational event is used as the pressure reference value, for example, 51.2 kPa, and the average effluent flow rate within 3 seconds prior to the start time of the operational event is used as the flow rate reference value, for example, 18.5 m³ / h. The pressure change judgment threshold is set to 0.8 kPa, and the flow rate change judgment threshold is set to 0.2 m³ / h. When the change in effluent pressure relative to the pressure reference value reaches 0.8 kPa and lasts for 0.5 seconds, this moment is determined as the pressure start time; when the change in effluent flow rate relative to the flow rate reference value reaches 0.2 m³ / h and lasts for 0.5 seconds, this moment is determined as the flow rate start time. The pressure start time and the flow rate start time can be obtained in this way, and the difference between the two is calculated to form the response delay interval, for example, 1.5 seconds.

[0029] The time range from the start of the running event to the start of the flow rate change is defined as the inertial response observation segment. Based on the pressure segment index space established in step one, the effluent pressure change sequence within the inertial response observation segment is mapped to a pressure segment index sequence. Within the inertial response observation segment, the first-order difference symbol sequence of the pressure segment index sequence is calculated, and the number of symbol changes is counted to determine the number of trajectory direction changes. Simultaneously, the hysteresis area and trajectory span of the pressure segment index sequence are calculated, where the trajectory span is the difference between the maximum and minimum pressure segment indexes of the pressure segment index sequence. In this embodiment, the inertial response observation segment is from 10:15:20.0 to 10:15:22.1. Based on the pressure segment index space established in step one, for example, with a predetermined pressure step size of 0.5 kPa and a static pressure lower limit threshold of 45.0 kPa, any pressure value can be determined by: Pressure segment index = The positioning is performed. The sequence of water pressure changes within the inertial response observation segment is mapped to a pressure segment index sequence, for example, the index sequence [12,13,13,14,15,16,16,17,17]. Then, the difference between adjacent indices is calculated to obtain a first-order difference sequence, and a first-order difference sign sequence is formed based on the positive and negative changes, for example, [+,0,+,+,+,0,+,0]. When counting the number of trajectory direction changes, cases with a first-order difference value of 0 are not included in the direction change statistics; only the changes between positive and negative signs are counted, thus obtaining the number of trajectory direction changes, for example, 3 times. Simultaneously, the trajectory span is obtained as 5 by calculating the difference between the maximum pressure segment index 17 and the minimum pressure segment index 12 in this sequence. The hysteresis area is obtained by multiplying and summing the index offset of each sampling point by the sampling period, for example, accumulating to 9.8 index·s.

[0030] Finally, when the number of trajectory direction changes reaches the direction change judgment threshold and the hysteresis loop area reaches the hysteresis area judgment threshold, the inertial migration rate is determined by the ratio of the trajectory span to the response delay interval, and the inertial migration trajectory feature set is determined based on the inertial migration rate and the trajectory span. In implementation, the direction change judgment threshold is set to 2 times, and the hysteresis area judgment threshold is set to 8.0 index·s. When the number of trajectory direction changes is ≥2 and the hysteresis loop area is ≥8.0 index·s, the inertial response condition is met. Then, the inertial migration rate is calculated according to: inertial migration rate = trajectory span / response delay interval. For example, if the trajectory span is 5 and the response delay interval is 1.5s, then the inertial migration rate is 3.33 index / s. Finally, the inertial migration rate of 3.33 index / s and the trajectory span of 5 are combined to form the inertial migration trajectory feature set, thereby completing the extraction of the inertial migration trajectory features and ensuring that the data source and calculation path of this feature are consistent with the aforementioned running event start time, response delay interval, and pressure segment index space, so that this embodiment can be completely reproduced.

[0031] Step 3: Set up at least two pressure measurement points in the outlet pipeline to obtain pressure change curves. Identify abnormal pressure propagation sections based on the fitting residual statistics and propagation time shift, and map them to the pressure section index space to form a propagation migration trajectory. By setting up at least two pressure measurement points in the outlet pipeline to obtain pressure change curves, the pressure propagation process in the pipeline can be monitored synchronously, allowing the propagation relationship of pressure fluctuations in the pipeline to be observed. By fitting the pressure change curves and identifying abnormal pressure propagation sections based on the fitting residual statistics, sections where the pressure propagation process differs from the stable propagation law can be determined. At the same time, the propagation time shift can reflect the propagation characteristics of pressure fluctuations between different pressure measurement points. Mapping the identified abnormal pressure propagation sections to the pressure section index space can form a propagation migration trajectory, allowing a unified description of the changes in pressure propagation anomalies in the pressure section index space.

[0032] Specifically, in this embodiment, at least two pressure measurement points are set on the outlet pipeline to obtain pressure change curves within the same operating cycle. The first pressure measurement point is located 0.2m downstream of the submersible pump outlet, and the second pressure measurement point is located 6.0m downstream of the outlet pipeline. The two pressure measurement points are synchronously collected using the same sampling period of 0.1s. The pressure change curves are segmented according to the operating cycle time determined in step one, with the operating cycle time being 30s. To ensure comparability of pressure propagation timing, piecewise linear fitting is performed on the pressure change curves of the two pressure measurement points within the same operating cycle. The segmentation method is to divide the operating cycle into 5 segments with equal time intervals and perform linear fitting on each segment to obtain the fitting residual for each sampling point. The pressure values ​​at each sampling time are mapped to the pressure segment index space established in step one, thereby determining the pressure segment to which each sampling point belongs; the fitting residual statistics are calculated using the root mean square value of the fitting residuals of each sampling point within the pressure segment; when the fitting residual statistics of a sampling point within a certain pressure segment reaches or exceeds 0.35 kPa, the pressure segment is determined to be an abnormal pressure propagation segment.

[0033] The propagation time shift of the pressure change curves at two pressure measurement points is calculated synchronously using the cross-correlation peak method: A cross-correlation function is calculated for the two pressure change curves within the same operating cycle, and the time shift corresponding to the cross-correlation peak is taken as the propagation time shift. The median of the propagation time shift over 20 consecutive operating cycles during the stable operating phase is used as the propagation time shift benchmark value, and a propagation time shift offset threshold of 0.05s is set. When the offset of the propagation time shift relative to the propagation time shift benchmark value reaches or exceeds 0.05s, the operating cycle is determined to be a propagation abnormal operating cycle. In this embodiment, the propagation time shift benchmark value is 0.12s, and the propagation time shift of a certain operating cycle is 0.18s, with an offset of 0.06s, satisfying the propagation time shift offset threshold, thus determining this operating cycle as a propagation abnormal operating cycle.

[0034] The abnormal pressure propagation sections are determined based on the statistical values ​​of the fitted residuals, and the abnormal propagation cycle is determined based on the propagation time shift. These abnormal pressure propagation sections are then mapped to the pressure section index space to form a propagation migration trajectory. This embodiment uses the pressure section index space from step one, with a static pressure lower limit threshold of 45.0 kPa and a predetermined pressure step size of 0.5 kPa. The pressure section index calculation formula is: Pressure section index = Where P is the pressure value at the sampling time. In this embodiment, the pressure of 51.8 kPa corresponds to the pressure range index. Pressure zone index corresponding to 52.8 kPa pressure When the pressure propagation anomaly segment identified within a certain operating cycle covers pressure segment indices 14-16, the pressure propagation anomaly segment is mapped to the pressure segment index space to form a propagation migration trajectory. The propagation migration trajectory consists of a sequence of the index positions of the pressure propagation anomaly segment in the pressure segment index space within that operating cycle as the operating cycle time changes.

[0035] Within the same operating cycle, the trajectory span metric of the propagation migration trajectory is calculated; the trajectory span metric growth is calculated between adjacent operating cycles; the trajectory center of gravity migration is calculated between adjacent operating cycles; when the trajectory span metric growth reaches the expansion judgment threshold and the trajectory center of gravity migration reaches the center of gravity migration judgment threshold, it is determined that the pressure propagation anomaly segment has undergone directional expansion and forms a propagation migration trajectory feature set. In this embodiment, the trajectory span metric is defined as the difference between the maximum pressure segment index and the minimum pressure segment index corresponding to the pressure propagation anomaly segment; in this embodiment, the pressure propagation anomaly segment in operating cycle i is 14-16, so the trajectory span metric is 16-14=2. Between adjacent operating cycles, the trajectory span metric growth is defined as the trajectory span metric of operating cycle i+1 minus the trajectory span metric of operating cycle i; in this embodiment, the pressure propagation anomaly segment in operating cycle i+1 expands to 13-17, so the trajectory span metric of operating cycle i+1 is 17-13=4, and the trajectory span metric growth is 4-2=2. In the trajectory centroid migration, the centroid value of the pressure segment index in a single operating cycle is defined as the average of the maximum and minimum pressure segment indices of the abnormal pressure propagation segment in that operating cycle. In this embodiment, the centroid value of the pressure segment index in operating cycle i is (14+16) / 2=15.0, and the centroid value of the pressure segment index in operating cycle i+1 is (13+17) / 2=15.0. The trajectory centroid migration is defined as the cumulative difference between the centroid values ​​of the pressure segment index in adjacent operating cycles. In this example, the centroid values ​​of the pressure segment index are 15.0, 15.0, and 16.0 in three consecutive operating cycles, respectively. Therefore, the trajectory centroid migration is |15.0-15.0|+|16.0-15.0|=1.0. The expansion judgment threshold is set to 2, and the centroid migration judgment threshold is set to 0.5. When the trajectory span increase reaches or exceeds 2 and the trajectory centroid migration reaches or exceeds 0.5, it is determined that the abnormal pressure propagation segment has undergone directional expansion.

[0036] Finally, a "propagation migration trajectory feature set" is formed. In this embodiment, when the conditions of "the trajectory span growth reaches the expansion judgment threshold and the trajectory center of gravity migration reaches the center of gravity migration judgment threshold" are met, the propagation migration trajectory, trajectory span, trajectory span growth, and trajectory center of gravity migration in the corresponding continuous operating cycle are collectively constituted as the propagation migration trajectory feature set. In this embodiment, the pressure propagation anomaly segment corresponding to the propagation migration trajectory expands from 14-16 in operating cycle i to 13-17 in operating cycle i+1 and forms 14-18 on the high-pressure side in operating cycle i+2. The corresponding trajectory spans are 2, 4, and 4, the trajectory span growth is 2 and 0, and the cumulative trajectory center of gravity migration is 1.0, which meets the expansion judgment threshold and the center of gravity migration judgment threshold, thereby determining that the pressure propagation anomaly segment has undergone directional expansion and forming the propagation migration trajectory feature set.

[0037] Step 4: Monitor the pressure change curve during the submersible pump shutdown phase. When the pressure exceeds the upper static pressure threshold and the duration reaches the back-pull duration threshold, determine the water column back-pull response zone and calculate the back-pull area to form the shutdown back-pull migration trajectory. By monitoring the pressure change curve during the submersible pump shutdown phase, the pressure change process after shutdown can be continuously recorded. Determining the water column back-pull response zone when the pressure exceeds the upper static pressure threshold and the duration reaches the back-pull duration threshold can identify the back-pull phenomenon caused by the water column in the pipeline after shutdown. By calculating the back-pull area within the water column back-pull response zone, the cumulative degree of pressure exceeding the upper static pressure threshold can be reflected, and this process can be mapped to the pressure segment index space to form the shutdown back-pull migration trajectory. This allows the pressure change process during the shutdown phase to be expressed in the pressure segment index space, thereby providing characteristic information of the shutdown phase for subsequent risk status analysis.

[0038] Specifically, in this embodiment, the submersible pump shutdown time is defined as the moment when the motor speed first drops to 0 r / min and the duration is not less than 0.5 s, denoted as shutdown time T0, for example, T0 = 10:18:30.0. After the submersible pump shutdown time, the water pressure change sequence is continuously collected at a preset sampling period of 0.1 s. The static pressure upper limit threshold determined in step one is used as the backtracking judgment criterion to determine the segment of the water pressure change sequence, where the static pressure upper limit threshold is 55.0 kPa in an example. The backtracking duration threshold is set to 0.8 s. When the water pressure change sequence is continuously higher than 55.0 kPa and the duration reaches 0.8 s, the water column backtracking response zone is determined. For example, during the period from 10:18:31.2 to 10:18:32.4, the water pressure is continuously higher than 55.0 kPa for a duration of 1.2 s. Therefore, 10:18:31.2 to 10:18:32.4 is determined as the water column backtracking response zone. There are 12 sampling intervals within this time interval, corresponding to 13 sampling points, and the calculation process of the backtracking area and the shutdown backtracking migration trajectory begins.

[0039] Secondly, the cumulative time of the portion of the outlet pressure value exceeding the upper limit threshold of static pressure within the water column backtracking response zone is calculated to determine the backtracking area. Then, based on the pressure segment index space, the sequence of outlet pressure changes within the water column backtracking response zone is mapped to a pressure segment index sequence. In this embodiment, the backtracking area is defined as the cumulative time of the portion of the outlet pressure value exceeding the upper limit threshold of static pressure within the water column backtracking response zone, i.e., backtracking area = Σ(P(t) i (-static pressure upper limit threshold) × sampling period.

[0040] Where P(t) iLet be the water pressure value at the i-th sampling time, with a sampling period of 0.1s. In the example, the pressures at 13 consecutive sampling points within the water column backtracking response zone are: 55.3, 55.8, 56.5, 56.9, 56.2, 55.7, 55.4, 55.1, 55.6, 56.0, 55.5, 55.2, and 55.1 kPa, respectively. The corresponding excess pressures are: 0.3, 0.8, 1.5, 1.9, 1.2, 0.7, 0.4, 0.1, 0.6, 1.0, 0.5, 0.2, and 0.1 kPa.

[0041] Therefore, the area calculated from the back calculation is: (0.3+0.8+1.5+1.9+1.2+0.7+0.4+0.1+0.6+1.0+0.5+0.2+0.1)×0.1=0.93kPa·s.

[0042] Subsequently, the water pressure change sequence within the water column backtracking response zone is mapped based on the pressure segment index space established in step one. An example of the static pressure lower limit threshold is 45.0 kPa, and an example of the predetermined pressure step size is 0.5 kPa. The pressure segment index = .

[0043] For example, a pressure of 55.3 kPa corresponds to pressure segment index 21, and a pressure of 56.9 kPa corresponds to pressure segment index 24, thus obtaining the pressure segment index sequence within the water column backtracking response zone: [21,22,24,24,23,22,21,21,22,23,22,21,21]. This pressure segment index sequence is used as the basis for the index expression of the shutdown backtracking migration trajectory.

[0044] Within the water column back-pushing response zone, the first-order differential symbol sequence of the pressure segment index sequence is calculated, and the number of consecutive fluctuation segments in the first-order differential symbol sequence that change from positive to negative and then from negative to positive is determined as the number of index cycles. At the same time, the index centroid value of the pressure segment index sequence within each index cycle is calculated, and the cumulative difference of the index centroid values ​​of adjacent index cycles is determined as the centroid migration amount. The proportion of sampling points in the first-order differential symbol sequence that maintain the same symbol within each index cycle is determined as the directional consistency ratio. In this embodiment, for the pressure segment index sequence [21,22,24,24,23,22,21,21,22,23,22,21,21], the adjacent differences are calculated to obtain the first-order difference sequence [+1,+2,0,-1,-1,-1,0,+1,+1,-1,-1,0], and the sampling points with a difference value of 0 are not included in the symbol sequence, thereby obtaining the index first-order difference symbol sequence [+,+,-,-,-,+,+,-,-].

[0045] According to the rule of determining an index cycle based on a continuous fluctuation segment of "from positive to negative and then from negative to positive", this sequence forms only one complete "+→-→+" structure, therefore the index cycle count is 1. To ensure that the index cycle segment truncation rule is clear, this embodiment stipulates that the corresponding segment of the index cycle is defined as the pressure segment index set from the first appearance of the positive change symbol "+" to the end of the first "+" corresponding sampling point after the completion of the "+→-→+" structure. In this example, the pressure segment index sequence corresponding to this index cycle is: [21,22,24,24,23,22,21,21,22,23,22].

[0046] Within this index cycle, the average value of the pressure segment index sequence is calculated as the index centroid value, i.e. (21+22+24+24+23+22+21+21+22+23+22) / 11=22.27.

[0047] The directional consistency ratio is calculated as the ratio of the length of the longest consecutive segment with the same symbol within the index cycle to the number of non-zero differential sampling points within the index cycle. For example, in the symbol sequence [+,+,-,-,-,+,+], the length of the longest consecutive segment with the same symbol is 3, and the number of non-zero differential sampling points is 7. Therefore, the directional consistency ratio is 3 / 7 = 0.43. In this embodiment, the index cycle number and the directional consistency ratio are calculated within the single water column backtracking response region.

[0048] Finally, a set of abnormal shutdown backtracking events is determined when the number of index loops reaches the loop count threshold, the center of gravity migration amount reaches the center of gravity migration threshold, and the direction consistency ratio reaches the direction consistency threshold. Within this set, the ratio of the backtracking area to the duration of the water column backtracking response zone is calculated to determine the backtracking intensity coefficient. Based on the backtracking intensity coefficient, the number of index loops, and the center of gravity migration amount, a set of shutdown backtracking migration trajectory features is formed. In this embodiment, the loop count threshold is set to 1, the center of gravity migration threshold is set to 0.50, and the direction consistency threshold is set to 0.40. A set of abnormal shutdown backtracking events is determined when the number of index loops is ≥1, the center of gravity migration amount is ≥0.50, and the direction consistency ratio is ≥0.40. The center of gravity migration amount is calculated between two adjacent water column backtracking response zones. In this embodiment, the index centroid values ​​of two consecutive water column backtracking response zones are 22.27 and 22.87, respectively. Therefore, the center of gravity migration amount |22.87-22.27|=0.60, which satisfies the center of gravity migration threshold. In the example, the back-pushing area is 0.93 kPa·s, and the duration of the water column back-pushing response zone is 1.2 s. Therefore, the back-pushing intensity coefficient = 0.93 / 1.2 = 0.78 kPa, which represents the average back-pushing pressure intensity per unit time. Finally, based on the back-pushing intensity coefficient of 0.78 kPa, the number of index cycles of 1, and the center of gravity migration amount of 0.60, a set of features for the shutdown back-pushing migration trajectory is formed.

[0049] Step 5: Perform correlation analysis on the inertial migration trajectory, propagation migration trajectory, and shutdown retrograde migration trajectory within the pressure segment index space to construct a risk state discrimination code. Based on the risk state discrimination code, identify the idling risk state, air intake risk state, cavitation risk state, and backflow reversal risk state, and execute corresponding protection controls. By performing correlation analysis on the inertial migration trajectory, propagation migration trajectory, and shutdown retrograde migration trajectory within the pressure segment index space, a unified analysis of pressure change behavior formed by different operating stages and different physical processes can be performed. On this basis, a risk state discrimination code is constructed to encode and express the correlation between multiple types of migration trajectories, enabling the submersible pump's operating state to be identified under a unified discrimination structure. Then, based on the risk state discrimination code, identify the idling risk state, air intake risk state, cavitation risk state, and backflow reversal risk state, and execute corresponding protection controls. This allows the submersible pump to take corresponding protection measures under different risk states, thereby achieving monitoring and protection of the submersible pump's operation process.

[0050] Specifically, in this embodiment, the running cycle time is 30 seconds, the sampling period is 0.1 seconds, and the running cycle time is established with the starting time T1 = 10:20:00.0. The sampling point number is used as the time axis index, and the time axis index of the kth sampling point is denoted as k, corresponding to the time T1 + 0.1ks. The pressure segment index space adopts the pressure segment index space established in step one above. In this example, the static pressure lower limit threshold is 45.0 kPa, the predetermined pressure step size is 0.5 kPa, and the pressure segment index = Based on steps two, three, and four, the index position sequences of the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory within this operating cycle are obtained respectively, and then entered into correlation analysis under the same time axis index.

[0051] Secondly, within the same operating cycle, the time-series index positions of the inertial migration trajectory, propagation migration trajectory, and shutdown retrograde migration trajectory in the pressure segment index space are obtained, and a time axis index is established based on the operating cycle time. The inertial migration trajectory, propagation migration trajectory, and shutdown retrograde migration trajectory are synchronously mapped according to the time axis index, forming a trajectory set of the three types of migration trajectories in the time-pressure two-dimensional index space. In this embodiment, the index position sequence of the inertial migration trajectory is taken from the inertial response observation segment after the start time of the operating event. For example, within k=60—k=90 (i.e., 10:20:06.0—10:20:09.0), the index position sequence corresponding to the inertial migration trajectory is [12,13,13,14,15,16,16,17,17]; the index position sequence of the propagation migration trajectory is taken from the propagation anomaly operating cycle within the same operating cycle. For example, within k=68—k=96 (i.e., 10:20:06.8—10:20:09). 6) Within this period, the index position sequence corresponding to the propagation migration trajectory is [14,15,16,16,17,18,18,17,16]. The index position sequence of the shutdown backtracking migration trajectory is taken from the water column backtracking response zone during the shutdown phase. For example, at the end of this operating cycle, a water column backtracking response zone appears within k=250—k=262 (i.e., 10:20:25.0—10:20:26.2), and the index position sequence corresponding to the shutdown backtracking migration trajectory is [21,22,24,24,23,22,21,21,22,23,22,21,21]. All three types of index position sequences are written into the time-pressure two-dimensional index space with their respective time axis index intervals to form a trajectory set.

[0052] Third, in the trajectory set, identify the trajectory intersection segments where the inertial migration trajectory and the propagation migration trajectory have the same or adjacent pressure segment indices within the same time axis interval, and identify the trajectory intersection segments where the propagation migration trajectory and the shutdown backtracking migration trajectory have the same or adjacent pressure segment indices within the same time axis interval; calculate the duration and trajectory span of each trajectory intersection segment on the time axis, and determine the trajectory coupling segment when the duration of the trajectory intersection segment reaches the intersection time determination threshold and the trajectory span reaches the intersection trajectory span determination threshold; construct a risk status discrimination code based on the trajectory coupling segments formed by the inertial migration trajectory, the propagation migration trajectory, and the shutdown backtracking migration trajectory. In this embodiment, the determination of the trajectory intersection section adopts the following disclosed criteria: On the same time axis index k, if the index position of the inertial migration trajectory and the index position of the propagation migration trajectory satisfy the condition that "the pressure section index is the same or adjacent", then k is included in the trajectory intersection section of the inertial migration trajectory and the propagation migration trajectory; if the propagation migration trajectory and the shutdown backtracking migration trajectory satisfy the condition that "the pressure section index is the same or adjacent" on the same time axis index k, then k is included in the trajectory intersection section of the propagation migration trajectory and the shutdown backtracking migration trajectory. For both inertial migration and propagation migration trajectories, both exist simultaneously within the time interval k=68—k=90, and consecutive segments with the same or adjacent indices appear within this interval. For example, k=72—k=84 consecutively satisfy the adjacent relationship. Therefore, the duration of this trajectory intersection segment is (84-72+1)×0.1=1.3s. The trajectory span within this intersection segment is calculated as the difference between the index of the maximum pressure segment and the index of the minimum pressure segment in the corresponding segment's index position sequence. In the example, the merged index range within the intersection segment is 14—18, so the trajectory span is 18-14=4. In this embodiment, the intersection time determination threshold is set to 1.0s, and the intersection trajectory span determination threshold is set to 3. Therefore, this trajectory intersection segment satisfies both the "duration reaching the intersection time determination threshold and the trajectory span reaching the intersection trajectory span determination threshold," and is determined to be a trajectory coupling segment. For the propagation migration trajectory and the shutdown backtracking migration trajectory, since the time axes of the running segment and the shutdown segment do not overlap, no trajectory intersection segment is formed in this embodiment, and the corresponding bit in the subsequent risk status discrimination code is set to 0.In constructing the risk status discrimination code, this embodiment uses a two-bit binary encoding. The first bit of the risk status discrimination code is defined as follows: "The inertial migration trajectory and the propagation migration trajectory have a trajectory coupling segment" is recorded as 1, and "The inertial migration trajectory and the propagation migration trajectory do not have a trajectory coupling segment" is recorded as 0. The second bit of the risk status discrimination code is defined as follows: "The overlap length between the propagation trajectory segment and the backtracking trajectory segment reaches the propagation backtracking judgment threshold" is recorded as 1, and "The overlap length between the propagation trajectory segment and the backtracking trajectory segment does not reach the propagation backtracking judgment threshold" is recorded as 0. In this operating cycle, the first bit is 1 and the second bit is 0, therefore the example risk status discrimination code is [1,0], and it proceeds to the segment calculation and criterion calculation for risk status identification.

[0053] Finally, within the same operating cycle, the index position sequences of the inertial migration trajectory, propagation migration trajectory, and shutdown retrograde migration trajectory in the pressure segment index space are obtained respectively; within the pressure segment index space, the inertial trajectory segment corresponding to the inertial migration trajectory, the propagation trajectory segment corresponding to the propagation migration trajectory, and the retrograde trajectory segment corresponding to the shutdown retrograde migration trajectory are determined, wherein each trajectory segment is determined by the maximum pressure segment index and the minimum pressure segment index of the corresponding migration trajectory; the segment overlap length between the inertial trajectory segment and the propagation trajectory segment is calculated, and the segment overlap length between the propagation trajectory segment and the retrograde trajectory segment is also calculated, while the segment distance between the inertial trajectory segment and the retrograde trajectory segment is calculated; when the inertial trajectory segment... When the overlap length between the propagation trajectory segment and the propagation trajectory segment reaches the inertial propagation judgment threshold, but the overlap length between the propagation trajectory segment and the backtracking trajectory segment does not reach the propagation backtracking judgment threshold, it is determined to be an idling risk state; when the overlap length between the inertial trajectory segment and the propagation trajectory segment reaches the inertial propagation judgment threshold, and the overlap length between the propagation trajectory segment and the backtracking trajectory segment reaches the propagation backtracking judgment threshold, it is determined to be an air intake risk state; when the trajectory span increase of the propagation trajectory segment reaches the expansion judgment threshold, and the segment distance reaches the distance judgment threshold, it is determined to be a cavitation risk state; when the trajectory span of the backtracking trajectory segment reaches the backtracking segment judgment threshold, it is determined to be a backflow reversal risk state, and corresponding protection control is executed. In this embodiment, the inertial trajectory segment is determined by the maximum pressure segment index and the minimum pressure segment index of the inertial migration trajectory index position sequence. The inertial migration trajectory index position sequence is [12,13,13,14,15,16,16,17,17], therefore the inertial trajectory segment is [12,17]. The propagation trajectory segment is determined by the maximum pressure segment index and the minimum pressure segment index of the propagation migration trajectory index position sequence. The propagation migration trajectory index position sequence is: [14,15,16,16,17,18,18,17,16]; Therefore, the propagation trajectory segment is [14,18]; the backtracking trajectory segment is determined by the maximum pressure segment index and the minimum pressure segment index of the backtracking migration trajectory index position sequence. The backtracking migration trajectory index position sequence is [21,22,24,24,23,22,21,21,22,23,22,21,21], so the backtracking trajectory segment is [21,24]. The segment overlap length adopts the publicly available definition: for two closed intervals [a,b] and [c,d], the segment overlap length is defined as max(0,min(b,d)-max(a,c)+1). Therefore, the overlap length between the inertial trajectory segment and the propagation trajectory segment is min(17,18)-max(12,14)+1=17-14+1=4; the overlap length between the propagation trajectory segment and the backtracking trajectory segment is max(0,min(18,24)-max(14,21)+1)=max(0,18-21+1)=0; the segment distance adopts the publicly available standard: if the two segments do not overlap, the segment distance is defined as max(a,c)-min(b,d), so the segment distance between the inertial trajectory segment and the backtracking trajectory segment is 21-17=4. In this embodiment, the inertial propagation judgment threshold is set to 3, the propagation backtracking judgment threshold is set to 1, the distance judgment threshold is set to 3, and the backtracking segment judgment threshold is set to 2. Furthermore, the increase in the trajectory span of the propagation trajectory segment is calculated based on the difference in the trajectory span of the propagation trajectory segment between adjacent operating cycles. In the example, the propagation trajectory segment of the previous operating cycle is [14,16], and the trajectory span is 2. The propagation trajectory segment of this operating cycle is [14,18], and the trajectory span is 4. Therefore, the increase in the trajectory span is 4-2=2, and the expansion judgment threshold is set to 2. Based on the above data, this operating cycle meets the condition that "the overlap length between the inertial trajectory segment and the propagation trajectory segment reaches the inertial propagation judgment threshold, while the overlap length between the propagation trajectory segment and the retrograde trajectory segment does not reach the propagation retrograde judgment threshold." Therefore, it is determined to be in an idling risk state, and corresponding protection control is executed. In the example, the speed reduction protection adopts the following method: linearly reducing the motor speed control target from 2850 r / min to 2400 r / min, with a speed reduction slope of 150 r / min·s. -1 After deceleration, the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory are updated according to the operating cycle time to complete the risk status judgment in the subsequent operating cycle.

[0054] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters and thresholds in the formulas are set by those skilled in the art according to the actual situation.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A monitoring and protection method based on the operating status of a submersible pump, characterized in that, include: Step 1: Obtain the water level, pump body immersion depth, and outlet pipe height difference of the submersible pump operating environment, and calculate the static pressure reference pressure of the water column; Collect the effluent pressure change sequence during the stable operation phase and perform periodic statistics to obtain the upper and lower static pressure thresholds to determine the static pressure constraint zone; divide the pressure zone according to the predetermined pressure step size and establish a pressure zone index space, and map the effluent pressure change sequence to the pressure zone index sequence to form an environmental constraint mapping structure. Step 2: Monitor the changes in motor speed and motor current and determine the start time of the running event. Determine the start time of the changes in the sequence of changes in outlet water pressure and the sequence of changes in outlet water flow. Calculate the time difference between the two to form a response delay interval and map it to the pressure segment index space to obtain the inertial migration trajectory. Step 3: Set up at least two pressure measurement points in the outlet pipeline to obtain the pressure change curve. Identify the abnormal pressure propagation sections based on the fitting residual statistics and propagation time shift, and map them to the pressure section index space to form a propagation migration trajectory. Step 4: Monitor the pressure change curve during the submersible pump shutdown phase. When the pressure is higher than the upper limit threshold of static pressure and the duration reaches the pushback duration threshold, determine the water column pushback response zone and calculate the pushback area to form the shutdown pushback migration trajectory. Step 5: Perform correlation analysis on the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory within the pressure section index space to construct a risk status discrimination code. Based on the risk status discrimination code, identify the idling risk status, air intake risk status, cavitation risk status, and backflow reversal risk status, and execute the corresponding protection control.

2. The monitoring and protection method based on the operating status of a submersible pump according to claim 1, characterized in that, The construction of the static pressure constraint region includes the following steps: During the stable operation phase, the water pressure change sequence is continuously collected at a preset operating cycle time, and the water pressure change sequence of each operating cycle is mapped to the pressure segment index sequence according to the pressure segment index space established in step one of claim 1. In each operating cycle, the monotonicity index, hysteresis area, and inflection point count of the pressure segment index sequence are calculated. When the monotonicity index meets the monotonicity judgment threshold, the hysteresis area meets the hysteresis area judgment threshold, and the inflection point count meets the inflection point judgment threshold, the operating cycle is determined to be a stable cycle and a set of stable cycles is formed. Within the set of stable cycles, the periodic pressure intervals of the corresponding stable cycles are constructed by using the pressure interval index sequence to cover the minimum pressure interval index and the maximum pressure interval index in the pressure interval index space, and the periodic pressure intervals of multiple stable cycles are superimposed to form an interval overlap distribution. The consistent pressure interval is determined by the set of continuous pressure segment indexes in the interval overlap distribution that reach the overlap determination threshold. The upper boundary of the consistent pressure interval is defined as the upper limit threshold of static pressure, and the lower boundary of the consistent pressure interval is defined as the lower limit threshold of static pressure. Thus, the static pressure constraint zone is determined by the pressure interval between the upper limit threshold of static pressure and the lower limit threshold of static pressure.

3. The monitoring and protection method based on the operating status of a submersible pump according to claim 2, characterized in that, The partitioning of the pressure segment index space in step one includes the following steps: Using the static pressure reference pressure of the water column as the reference center, the water pressure change sequence of multiple operating cycles is continuously collected within the static pressure constraint zone, and the frequency of pressure occurrence of the water pressure change sequence on the pressure axis is statistically analyzed to form a pressure distribution density curve. Based on the pressure distribution density curve, the position where the density change slope reaches the density slope judgment threshold is determined as the candidate pressure boundary point, and the candidate pressure boundary points are screened according to the pressure axis order to form a boundary point set; Multiple pressure zones are formed between adjacent boundary points, and the median pressure of the pressure zone is used as the representative pressure value of that pressure zone. Each pressure segment is sequentially numbered according to the pressure offset between the representative pressure value and the static pressure reference pressure of the water column to form a pressure segment index, and the pressure segment index and the operating cycle time are used to construct the pressure segment index space. During the operation of a submersible pump, when the sequence of changes in outlet water pressure is mapped to the pressure segment index space, the pressure segment is located by determining the pressure segment corresponding to the outlet water pressure value and outputting the corresponding pressure segment index.

4. The monitoring and protection method based on the operating status of a submersible pump according to claim 1, characterized in that, The specific characteristics of the inertial migration trajectory in step two include the following steps: After determining the start time of the operating event, the start time of pressure change and the start time of flow change are determined according to the effluent pressure change sequence and the effluent flow rate change sequence, respectively, and the response delay interval is calculated. The time range between the start time of the running event and the start time of the flow rate change is defined as the inertial response observation segment, and the effluent pressure change sequence within the inertial response observation segment is mapped to the pressure segment index sequence based on the pressure segment index space established in step one. Within the inertial response observation segment, the first-order difference symbol sequence of the pressure segment index sequence is calculated, and the number of symbol changes is counted to determine the number of trajectory direction changes. At the same time, the hysteresis area and trajectory span of the pressure segment index sequence are calculated, where the trajectory span is the difference between the maximum pressure segment index and the minimum pressure segment index of the pressure segment index sequence. When the number of trajectory direction changes reaches the direction change determination threshold and the hysteresis loop area reaches the hysteresis area determination threshold, the inertial migration rate is determined by the ratio of the trajectory span to the response delay interval, and the inertial migration trajectory feature set is determined based on the inertial migration rate and the trajectory span.

5. The monitoring and protection method based on the operating status of a submersible pump according to claim 1, characterized in that, Specific characteristics of the propagation migration trajectory formed in step three Includes the following steps: Set up at least two pressure measurement points on the water outlet pipe and obtain the pressure change curve within the same operating cycle; The abnormal pressure propagation section is determined based on the statistical value of the fitting residual, and the abnormal propagation operation cycle is determined based on the propagation time shift. The abnormal pressure propagation segments are mapped to the pressure segment index space to form a propagation migration trajectory; Within the same running cycle, the trajectory span metric of the propagation migration trajectory is calculated, where the trajectory span metric is the difference between the maximum pressure segment index and the minimum pressure segment index corresponding to the pressure propagation anomaly segment; The trajectory span growth and trajectory centroid shift are calculated between adjacent operating cycles, where the trajectory centroid shift is the cumulative difference of the pressure segment index centroid value corresponding to the pressure propagation anomaly segment in adjacent operating cycles. When the growth of the trajectory span reaches the expansion judgment threshold and the migration of the trajectory center of gravity reaches the center of gravity migration judgment threshold, it is determined that the abnormal pressure propagation segment has undergone directional expansion and formed a propagation migration trajectory feature set.

6. The monitoring and protection method based on the operating status of a submersible pump according to claim 1, characterized in that, The specific characteristics of the shutdown backtracking migration trajectory obtained in step four include the following steps: After the submersible pump stops, the water pressure change sequence is continuously collected at a preset sampling period. The static pressure upper limit threshold is used as the back-pushing judgment benchmark to determine the segment of the water pressure change sequence. When the water pressure change sequence is continuously higher than the static pressure upper limit threshold and the duration reaches the back-pushing duration threshold, the water column back-pushing response zone is determined. The time accumulation of the portion of the water pressure value exceeding the upper limit threshold of static pressure within the water column back-pull response zone is calculated to determine the back-pull area. Based on the pressure segment index space, the sequence of water pressure changes within the water column back-pull response zone is mapped to the pressure segment index sequence. Within the water column back-pushing response zone, the first-order difference symbol sequence of the indexed sequence of the pressure section is calculated, and the number of consecutive fluctuation segments in the first-order difference symbol sequence of the index changing from positive to negative and then from negative to positive is determined as the number of index cycles. At the same time, the index centroid value of the indexed sequence of the pressure section within each index cycle is calculated, and the cumulative difference of the index centroid values ​​of adjacent index cycles is determined as the centroid migration amount. The proportion of sampling points in the first-order difference symbol sequence of the index that maintain the same symbol within each index cycle is determined as the directional consistency ratio. When the number of index loops reaches the loop count threshold, the centroid migration amount reaches the centroid migration threshold, and the direction consistency ratio reaches the direction consistency threshold, the set of shutdown pushback exception events is determined. Within the set of abnormal shutdown pushback events, the ratio of the pushback area to the duration of the water column pushback response zone is calculated to determine the pushback intensity coefficient. Based on the pushback intensity coefficient, the number of index cycles, and the center of gravity migration amount, a set of shutdown pushback migration trajectory features is formed.

7. The monitoring and protection method based on the operating status of a submersible pump according to claim 1, characterized in that, Step five, the association analysis process, includes the following steps: Within the same operating cycle, obtain the time series index positions of the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory in the pressure section index space, and establish a time axis index based on the operating cycle time; The inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory are synchronously mapped according to the time axis index, forming a set of three types of migration trajectories in the time-pressure two-dimensional index space; In the trajectory set, identify the intersection segments of the inertial migration trajectory and the propagation migration trajectory within the same time axis interval where the corresponding pressure segment index is the same or adjacent, and identify the intersection segments of the propagation migration trajectory and the shutdown pushback migration trajectory within the same time axis interval where the corresponding pressure segment index is the same or adjacent. Calculate the duration and span of each trajectory intersection segment on the time axis, and determine the trajectory coupling segment when the duration of the trajectory intersection segment reaches the intersection time determination threshold and the trajectory span reaches the intersection trajectory span determination threshold. Risk status discrimination codes are constructed based on the trajectory coupling segments formed by the inertial migration trajectory, the propagation migration trajectory, and the shutdown backtracking migration trajectory.

8. The monitoring and protection method based on the operating status of a submersible pump according to claim 1, characterized in that, Step five includes: Within the same operating cycle, the index position sequences of the inertial migration trajectory, propagation migration trajectory, and shutdown backtracking migration trajectory in the pressure section index space are obtained respectively; Within the pressure segment index space, determine the inertial trajectory segment corresponding to the inertial migration trajectory, the propagation trajectory segment corresponding to the propagation migration trajectory, and the backtracking trajectory segment corresponding to the shutdown backtracking migration trajectory, wherein each trajectory segment is determined by the maximum pressure segment index and the minimum pressure segment index of the corresponding migration trajectory; Calculate the segment overlap length between the inertial trajectory segment and the propagation trajectory segment, and calculate the segment overlap length between the propagation trajectory segment and the retrograde trajectory segment. At the same time, calculate the segment distance between the inertial trajectory segment and the retrograde trajectory segment. When the overlap length between the inertial trajectory segment and the propagation trajectory segment reaches the inertial propagation judgment threshold, but the overlap length between the propagation trajectory segment and the backtracking trajectory segment does not reach the propagation backtracking judgment threshold, it is determined to be an idling risk state. When the overlap length between the inertial trajectory segment and the propagation trajectory segment reaches the inertial propagation judgment threshold, and the overlap length between the propagation trajectory segment and the retrospective trajectory segment reaches the propagation retrospective judgment threshold, it is determined to be an air intake risk state. When the growth of the trajectory span of the propagation trajectory segment reaches the expansion judgment threshold and the segment distance reaches the distance judgment threshold, it is determined to be a cavitation risk state; when the trajectory span of the backtracking trajectory segment reaches the backtracking segment judgment threshold, it is determined to be a backflow reversal risk state.

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