Submersible motor operation control method and system

Abstract

The invention relates to the field of submersible motor operation control, in particular to a submersible motor operation control method and system. Comprising the following steps: firstly, stably operating under the condition of detecting an initial rotating speed, then executing short-time power-off inertial sliding, collecting and filtering the rotating speed, calculating an angular acceleration and curvature, obtaining a rotating speed attenuation curve, dividing a time window, and extracting characteristics such as a curvature mean value, a variance, an attenuation proportion and a linear residual error; through comparison of conventional sliding and braking / short-circuit sliding, after electromagnetic residues are quantified and deducted, the curvature trend and tail linearity of each window are analyzed according to a judgment rule, and fluid transient resistance and solid winding friction are distinguished; and if constant mechanical friction is judged to exist in the two tests, performing graded responses such as short-time speed-increasing throwing-off, forward and reverse rotation unwrapping and safe shutdown alarm. The technical problem that an existing submersible motor causes systematic failure in a water source containing flexible impurities is solved.

Description

Technical Field

[0001] This application relates to the field of submersible motor operation control, specifically to a submersible motor operation control method and system. Background Technology

[0002] In water intake projects, submersible motors typically drive pumps by speed regulation via inverters. Existing energy-saving controls are mostly based on pipeline pressure and motor current: when the pressure increases, the frequency and speed are automatically reduced, and the decrease in current amplitude is regarded as a reduction in load, thereby maintaining or further reducing the speed and entering a low-speed operation state with low flow and pressure maintenance.

[0003] However, in water sources containing long-fiber flexible impurities, the above logic has a serious blind spot: at high speeds, the impeller linear velocity and shear force are high, enabling self-cleaning; once the pressure rises and the system operates at low speeds for an extended period, flexible impurities easily form an initial entanglement at the impeller root and sealing gaps, causing the inlet channel to shrink, reducing the effective suction area, and consequently decreasing the output power and input current on the shaft. The control system misinterprets this as a further reduction in load, further maintaining or deepening the low-speed state, causing the entanglement to gradually develop into a "winch effect," damaging the mechanical seal, leading to high-pressure water seeping into the motor cavity, causing insulation degradation or even a short circuit. In the early stages of the fault, the current often decreases instead of increasing or remains at a low value, neither triggering overcurrent protection nor being partially offset by mechanical resistance characteristics. Traditional monitoring based on current and pressure cannot identify the initial signs of entanglement in time, failing to trigger the necessary speed-up self-cleaning or untangling actions, ultimately leading to system failure.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] This application discloses a submersible motor operation control method and system, which aims to solve the technical problem that existing submersible motors in water sources containing flexible impurities cannot provide reliable early warnings in the early stages of entanglement using traditional current and pressure monitoring methods, resulting in the control unit being unable to take timely restorative speed-up or cleaning actions, ultimately leading to systemic failure.

[0006] The technical solution of this application is as follows:

[0007] In a first aspect, this application discloses a method for controlling the operation of a submersible motor, comprising:

[0008] Before performing the short-term power outage inertial gliding test, the submersible motor is controlled to run stably at the preset initial test speed for a fixed period of time;

[0009] After stable operation, the submersible motor underwent a short-term power outage inertial gliding test, and quantitative evaluation was performed.

[0010] The submersible motor's rotational speed data is continuously collected at a preset sampling frequency, and the time point corresponding to each rotational speed value is recorded to obtain the original data sequence of rotational speed changes over time.

[0011] The original data sequence is filtered to obtain the rotational speed data sequence;

[0012] Based on the speed data sequence, the angular acceleration sequence and curvature sequence of the submersible motor during the inertial gliding process are calculated according to the preset sampling time interval, and the speed decay curve is obtained.

[0013] The speed decay curve is divided into multiple time windows according to time, and the multiple time windows include at least an early window, a transition window and a tail window;

[0014] For each time window, based on the corresponding curvature sequence and angular acceleration sequence, at least two of the following are extracted as scalar features: mean curvature, curvature variance, relative speed decay ratio, and linear residual ratio within the time window.

[0015] Perform control tests and compare the curvature characteristics under different test conditions to obtain quantitative results of electromagnetic residual contribution, and correct scalar characteristics based on electromagnetic residual contribution. The control tests include at least one conventional short-time power-off inertial coasting test and one coasting test in which the inverter output terminals are short-circuited or the inverter is put into braking mode at the same time as the power is off.

[0016] Based on the corrected scalar characteristics, the quantitative judgment rules are applied. By analyzing the curvature change trend in multiple time windows and the linearity characteristics of the rotational speed decay in the tail window, the transient resistance caused by the evolution of the yield pseudoplastic fluid structure and the approximately constant mechanical friction generated by solid entanglement are distinguished, and the preliminary judgment results of the inertial gliding test are obtained.

[0017] When the preliminary judgment result indicates the existence of approximately constant mechanical friction, a short-time power-off inertial gliding test is performed again after a preset time interval, and the quantitative judgment is repeated. When both of the previous and subsequent independent preliminary judgment results indicate the existence of approximately constant mechanical friction, the final judgment result of approximately constant mechanical friction caused by solid winding is confirmed to be generated.

[0018] Based on the final judgment, a graded response strategy is implemented. The graded response strategy includes at least controlling the submersible motor to perform short-term speed-up and / or alternating forward and reverse untangling, and performing a safety shutdown and issuing a fault alarm when the tangling cannot be untangled.

[0019] Secondly, this application also discloses a submersible motor operation control system, comprising:

[0020] The operation control module is used to control the submersible motor to run stably at a preset initial test speed for a fixed period of time before performing a short-term power failure inertial gliding test;

[0021] The operation control module is also used to perform a short-term power-off inertial gliding test on the submersible motor after stable operation, and to make quantitative judgments.

[0022] The data acquisition module is used to continuously acquire the speed data of the submersible motor at a preset sampling frequency, and record the time point corresponding to each speed value to obtain the original data sequence of speed change over time.

[0023] The filtering module is used to filter the original data sequence to obtain the rotational speed data sequence;

[0024] The parameter calculation module is used to calculate the angular acceleration sequence and curvature sequence of the submersible motor during the inertial coasting process based on the speed data sequence and according to the preset sampling time interval, so as to obtain the speed decay curve;

[0025] The time window division module is used to divide the speed decay curve into multiple time windows according to time. The multiple time windows include at least an early window, a transition window, and a tail window.

[0026] The feature extraction module is used to extract at least two of the following as scalar features for each time window, based on the corresponding curvature sequence and angular acceleration sequence: mean curvature, curvature variance, relative speed decay ratio, and linear residual ratio.

[0027] The electromagnetic residual deduction module is used to perform control tests and compare the curvature characteristics under different test conditions to obtain the quantitative results of electromagnetic residual contribution, and to correct the scalar characteristics based on the electromagnetic residual contribution. The control test includes at least one conventional short-time power-off inertial coasting test and one coasting test in which the inverter output terminals are short-circuited or the inverter is put into braking mode at the same time as the power is off.

[0028] The judgment rule module is used to apply quantitative judgment rules based on the modified scalar characteristics. According to the quantitative judgment rules, by analyzing the curvature change trend in multiple time windows and the linearity characteristics of the rotational speed decay in the tail window, it distinguishes between the transient resistance caused by the evolution of the yield pseudoplastic fluid structure and the approximately constant mechanical friction generated by solid entanglement, and obtains the preliminary judgment results of the inertial gliding test.

[0029] The repeat test module is used to perform a short-time power-off inertial gliding test again after a preset time interval when the preliminary judgment result indicates that there is approximately constant mechanical friction, and to repeat the quantitative judgment. When both of the previous and subsequent independent preliminary judgment results indicate that there is approximately constant mechanical friction, the final judgment result of approximately constant mechanical friction caused by solid winding is confirmed to be generated.

[0030] The response strategy module is used to execute a graded response strategy based on the final judgment result. The graded response strategy includes at least controlling the submersible motor to perform short-term speed-up and / or alternating forward and reverse untangling, and executing a safety shutdown and issuing a fault alarm when the tangling cannot be untangled.

[0031] Beneficial Effects: The submersible motor operation control method disclosed in this application ensures stable initial test conditions by controlling the submersible motor to run stably at a preset initial speed for a fixed period of time before performing a short-term power-off inertial coasting test. After stable operation, high-quality speed decay curves are obtained by continuously collecting and filtering speed data. Furthermore, this method calculates the angular acceleration and curvature sequences during the inertial coasting process and divides the speed decay curve into time windows to extract multiple scalar features, providing a rich data foundation for subsequent quantitative judgment. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating a submersible motor operation control method provided in this application.

[0033] Figure 2 A flowchart of a submersible motor operation control system provided in this application.

[0034] In the diagram: 1. Operation control module; 2. Data acquisition module; 3. Filtering module; 4. Parameter calculation module; 5. Time window division module; 6. Feature extraction module; 7. Electromagnetic residue deduction module; 8. Judgment rule module; 9. Repeated test module; 10. Response strategy module. Detailed Implementation

[0035] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0036] Reference Figure 1 This application discloses a method for controlling the operation of a submersible motor, comprising:

[0037] S1000: Before performing the short-term power failure inertial gliding test, control the submersible motor to run stably at the preset initial test speed for a fixed period of time;

[0038] S2000: After stable operation, the submersible motor begins a short-term power-off inertial coasting test, and quantitative judgment is performed:

[0039] S3000: Continuously collects the speed data of the submersible motor at a preset sampling frequency, and records the time point corresponding to each speed value to obtain the original data sequence of speed change over time;

[0040] S4000: Filters the original data sequence to obtain the rotational speed data sequence;

[0041] S5000: Based on the speed data sequence, calculate the angular acceleration sequence and curvature sequence of the submersible motor during the inertial coasting process according to the preset sampling time interval, and obtain the speed decay curve;

[0042] S6000: Divide the speed decay curve into multiple time windows according to time, and the multiple time windows include at least an early window, a transition window and a tail window;

[0043] S7000: For each time window, based on the corresponding curvature sequence and angular acceleration sequence, at least two of the following are extracted as scalar features: mean curvature, curvature variance, relative speed decay ratio, and linear residual ratio within the time window;

[0044] S8000: Perform control experiments and compare the differences in curvature characteristics under different test conditions to obtain quantitative results of electromagnetic residual contribution, and correct scalar characteristics based on electromagnetic residual contribution;

[0045] The control test includes at least one routine short-term power outage inertial coasting test and one coasting test in which the inverter output terminals are short-circuited or the inverter is put into braking mode at the same time as the power is cut off.

[0046] S9000: Based on the modified scalar characteristics, the quantitative judgment rules are applied. According to the quantitative judgment rules, by analyzing the curvature change trend in multiple time windows and the linearity characteristics of the rotational speed decay in the tail window, the transient resistance caused by the evolution of the yield pseudoplastic fluid structure and the approximately constant mechanical friction generated by solid entanglement are distinguished, and the preliminary judgment results of the inertial gliding test are obtained.

[0047] S10000: When the preliminary judgment result indicates the existence of approximately constant mechanical friction, a short-time power-off inertial gliding test is performed again after a preset time interval, and the quantitative judgment is repeated. When both of the previous and subsequent independent preliminary judgment results indicate the existence of approximately constant mechanical friction, the final judgment result of approximately constant mechanical friction caused by solid winding is confirmed to be generated.

[0048] S11000: Based on the final judgment result, execute the graded response strategy. The graded response strategy includes at least controlling the submersible motor to perform short-term speed-up and / or alternating forward and reverse untangling, and executing a safety shutdown and issuing a fault alarm when the tangling cannot be untangled.

[0049] Specifically, the submersible motor mentioned in this application refers to a motor capable of operating in an underwater environment, typically integrated with a water pump for pumping water or transporting fluids. Its operation control methods aim to optimize motor performance, extend service life, and prevent malfunctions. The short-time power-off inertial coasting test is a diagnostic test that assesses the mechanical characteristics of the motor and its load by monitoring the speed decay process under inertia after power is cut off. The initial speed is the specific speed at which the motor is stably running before the inertial coasting test; this speed is the starting point of the test. The preset sampling frequency refers to the number of data points collected per second during data acquisition, used to ensure the accuracy of the speed data sequence. The angular acceleration sequence represents the change in the motor speed rate over time, reflecting the influence of resistance on motor deceleration. The curvature sequence describes the degree of curvature of the speed decay curve, sensitively reflecting subtle changes in resistance characteristics. The time window divides the entire inertial coasting process into different time periods to analyze the resistance characteristics at different stages. The early window typically reflects the initial resistance, the transition window reflects the resistance change process, and the tail window reflects the resistance characteristics after stabilization. Scalar characteristics are quantitative indicators extracted from angular acceleration and curvature sequences, such as mean and variance, used to characterize resistance properties within each time window. Electromagnetic residual contribution refers to the additional resistance or acceleration effect on the speed decay process after the motor is powered off due to internal electromagnetic effects (such as residual magnetism, inverter parasitic capacitance discharge, etc.). Yielding pseudoplastic fluid refers to a fluid whose viscosity decreases under shear stress; its structural evolution causes transient resistance. Solid entanglement refers to long fibrous impurities entangled on motor or pump components, generating approximately constant mechanical friction.

[0050] Before performing a short-duration power outage inertial coasting test, the submersible motor needs to be controlled to run stably at a preset initial test speed for a fixed period of time. For example, the output frequency of the inverter can be adjusted to allow the submersible motor to run stably at 1000 rpm for 30 seconds. During this period, the system can monitor parameters such as motor current, voltage, and vibration to ensure that the motor is in a stable operating state, providing reliable initial conditions for the subsequent inertial coasting test. The purpose of this stable operation is to eliminate transient effects during startup or frequency conversion, ensuring the accuracy of the test results.

[0051] After stable operation, the submersible motor undergoes a short-term power-off inertial coasting test, followed by quantitative evaluation. First, the motor's rotational speed data is continuously collected at a preset sampling frequency, and the time point corresponding to each speed value is recorded to obtain the raw data sequence of speed changes over time. For example, the sampling frequency can be set to 100Hz, meaning 100 speed data points are collected per second, and the timestamp of each data point is recorded. This raw data can be acquired by an encoder or Hall sensor mounted on the motor shaft and transmitted to the control system via a data acquisition card.

[0052] Subsequently, the original data sequence is filtered to obtain the rotational speed data sequence. The original data may contain noise; for example, high-frequency noise can be removed using methods such as moving average filtering, Kalman filtering, or wavelet filtering to obtain a smoother and more accurate rotational speed data sequence for subsequent calculations and analysis.

[0053] Based on the speed data sequence, the angular acceleration and curvature sequences of the submersible motor during inertial coasting are calculated according to a preset sampling time interval, resulting in the speed decay curve. For example, angular acceleration and curvature can be calculated every 0.1 seconds. Angular acceleration can be obtained by performing a first-order difference or numerical differentiation on the speed data sequence, while curvature can be calculated using the second and first derivatives of the speed decay curve. These sequences together constitute the detailed characteristics of the speed decay curve, reflecting the dynamic changes in the resistance experienced by the motor during inertial coasting.

[0054] Next, the speed decay curve is divided into multiple time windows, each including at least an early window, a transition window, and a tail window. For example, the first 2 seconds of the inertial coasting test can be defined as the early window, 2 to 5 seconds as the transition window, and after 5 seconds as the tail window. This division helps in analyzing the drag characteristics at different stages, because fluid resistance may dominate in the early stages of inertial coasting, while mechanical friction may become more significant in the later stages.

[0055] For each time window, based on the corresponding curvature and angular acceleration sequences, at least two of the following are extracted as scalar features: mean curvature, curvature variance, relative speed decay ratio, and linear residual ratio. For example, in the early window, the mean curvature and relative speed decay ratio can be calculated; in the transition window, the curvature variance and linear residual ratio can be calculated. These scalar features quantify the speed decay characteristics within each time window, providing a basis for subsequent judgments.

[0056] To accurately distinguish between fluid resistance and solid entanglement, a control test is required to compare the curvature characteristics under different test conditions. This allows for the quantification of the electromagnetic residual contribution, and the scalar characteristics are then corrected based on this contribution. The control test includes at least one routine short-duration power-off inertial coasting test and one coasting test where the inverter output terminals are short-circuited or the inverter is in braking mode simultaneously with power failure. For example, in the routine test, the inverter is in an open-circuit state after the motor is powered off; while in the control test, the inverter output terminals are short-circuited when the motor is powered off to eliminate or minimize the electromagnetic residual effect. By comparing the differences in curvature characteristics under these two test conditions, the impact of electromagnetic residual on the speed decay curve can be quantified and subtracted from the scalar characteristics, resulting in a purer mechanical resistance characteristic.

[0057] Based on the corrected scalar characteristics, a quantitative judgment rule is applied. By analyzing the curvature change trend within multiple time windows and the linearity of rotational speed decay in the tail window, a preliminary judgment result for the inertial gliding test is obtained, distinguishing between transient drag caused by the evolution of a yielding pseudoplastic fluid structure and approximately constant mechanical friction generated by solid entanglement. For example, if the curvature changes drastically in the early windows and the linearity of rotational speed decay in the tail window is poor, it may indicate transient drag caused by a yielding pseudoplastic fluid; if the linearity of rotational speed decay in the tail window is good and the curvature change is gradual, approximately constant mechanical friction may exist, which is usually an indication of solid entanglement.

[0058] When the initial assessment indicates the presence of approximately constant mechanical friction, a short-duration power-off inertial coasting test is performed again after a preset time interval, and the quantitative assessment is repeated. For example, after the first assessment confirms the presence of mechanical friction, the system can wait 10 minutes and then perform the inertial coasting test again. When both independent initial assessments indicate the presence of approximately constant mechanical friction, a final assessment result confirming the presence of approximately constant mechanical friction caused by solid entanglement is generated. This repeated verification mechanism effectively avoids misjudgments and improves the reliability of the diagnosis.

[0059] Based on the final assessment, a tiered response strategy is implemented. This strategy includes at least controlling the submersible motor to briefly increase its speed to detach and / or alternately reverse direction to untangle the entangled material, and executing a safety shutdown and issuing a fault alarm if the entanglement cannot be resolved. For example, if the entanglement is determined to be minor, the system can briefly increase the motor's speed to 1500 rpm to increase shear force and detach the entangled material; if the entanglement is more severe, it can attempt alternating forward and reverse operation to try and untangle the material. If these measures are ineffective, a safety shutdown and fault alarm are executed to prevent further damage to the motor.

[0060] The submersible motor operation control method of this application aims to address the shortcomings of traditional current and pressure monitoring methods in early warning of submersible motor winding. Traditional methods often misinterpret the initial current drop in winding as a load reduction, leading to continuous low-speed operation of the motor, accelerating winding formation and ultimately causing failure. This application, by introducing a short-term power-off inertial coasting test and performing refined analysis of the speed decay curve, can effectively distinguish between fluid transient resistance and the approximately constant mechanical friction generated by solid winding.

[0061] In another embodiment of this application, S9000 is further proposed to include:

[0062] S9100: Collects ambient temperature and concentration parameters of the yield pseudoplastic fluid;

[0063] S9200: Collects the historical operating speed of the submersible motor within a preset time period before the short-term power failure inertial coasting test;

[0064] S9300: Based on ambient temperature, concentration parameters, and historical operating speed, dynamically adjust the judgment threshold used to evaluate the curvature change trend and the linearity characteristics of speed decay in the tail window.

[0065] S9400: Based on the corrected scalar characteristics and dynamically adjusted judgment thresholds, by analyzing the curvature change trend within multiple time windows and the linearity characteristics of rotational speed decay in the tail window, the transient resistance caused by the evolution of yield pseudoplastic fluid structure and the approximately constant mechanical friction generated by solid entanglement are distinguished, and a preliminary judgment result is obtained.

[0066] The acquisition of ambient temperature and concentration parameters of the yield pseudoplastic fluid refers to obtaining real-time temperature data and fluid concentration information of the submersible motor's operating environment through appropriate sensors or detection equipment. These parameters are key factors affecting the rheological properties of the yield pseudoplastic fluid. For example, increased temperature may lead to a decrease in fluid viscosity, while changes in concentration directly affect the fluid's yield stress. Collecting the historical operating speed of the submersible motor within a preset time period before the short-term power-off inertial coasting test aims to obtain information about the motor's operating status during the period prior to the inertial coasting test. Historical operating speeds can reflect the structural evolution state that the fluid may undergo during long-term motor operation, such as the impact of shear history on the fluid's microstructure, which is crucial for accurately assessing fluid resistance characteristics.

[0067] Furthermore, based on ambient temperature, concentration parameters, and historical operating speeds, the judgment thresholds used to evaluate the curvature change trends within multiple time windows and the linearity of speed decay in the tail window are dynamically adjusted. This means that the system no longer uses fixed judgment thresholds, but instead calculates the most suitable judgment threshold for the current operating conditions based on real-time environmental and operating conditions, using preset rheological models, empirical formulas, or machine learning algorithms. For example, under high temperature and low concentration conditions, fluid resistance may be relatively small, and the judgment threshold can be lowered accordingly; while under low temperature and high concentration conditions, fluid resistance may be relatively large, and the judgment threshold can be appropriately raised. Thus, based on the corrected scalar characteristics and dynamically adjusted judgment thresholds, by analyzing the curvature change trends within multiple time windows and the linearity of speed decay in the tail window, the system can more accurately distinguish between transient resistance caused by the evolution of yielding pseudoplastic fluid structures and approximately constant mechanical friction generated by solid entanglement, thereby obtaining more accurate preliminary judgment results.

[0068] The proposed solution introduces ambient temperature, fluid concentration parameters, and the historical operating speed of the submersible motor as key factors affecting the judgment threshold, which can more comprehensively reflect the actual complexity of the submersible motor's operating conditions.

[0069] In some preferred embodiments, it is assumed that the submersible motor is operating downhole in an oil field, and the fluid is a high-viscosity, yield-pseudoplastic drilling fluid. In the high-temperature environment of summer, the viscosity of the drilling fluid may decrease, and its yield stress characteristics may also change, resulting in different transient resistance characteristics during inertial gliding compared to the low-temperature environment of winter. If a fixed judgment threshold is used, in summer, the fluid resistance characteristics may change, leading to misjudgment of solid entanglement, or in winter, the increased fluid resistance characteristics may cause missed detection of true solid entanglement.

[0070] The specific implementation of this application is as follows: First, the ambient temperature is collected by a temperature sensor installed near the wellhead or motor, and the drilling fluid concentration parameter is obtained through a fluid analyzer or preset parameters. Simultaneously, the average operating speed of the submersible motor over the past 24 hours is extracted from the historical data records of the motor controller. For example, if the current ambient temperature is 80℃, the drilling fluid concentration is 1.2 g / cm³, and the historical average speed is 1500 rpm, the system inputs these parameters into a preset rheological model or empirical database, dynamically calculating and adjusting the judgment thresholds used to evaluate the curvature change trends within the early, transition, and tail windows, as well as the linearity characteristics of the speed decay in the tail window. For example, based on high temperature and high concentration conditions, the system may appropriately increase the curvature change rate threshold distinguishing between transient resistance and solid entanglement, and adjust the linearity judgment threshold of the tail window to be more stringent. Subsequently, based on the corrected scalar characteristics and these dynamically adjusted judgment thresholds, the inertial gliding test data is analyzed to more accurately distinguish between fluid effects and solid entanglement, obtaining preliminary judgment results. In this way, high-precision fault diagnosis capabilities can be maintained even when environmental conditions and fluid properties change significantly.

[0071] In another embodiment of this application, a control experiment is further proposed to compare the differences in curvature characteristics under different test conditions to obtain quantitative results of electromagnetic residual contribution, including:

[0072] S8100: When performing the control test, when the submersible motor drive power supply is disconnected and the inverter output terminal is in the first electromagnetic state, the first short-time power failure inertial coasting test is performed, the first speed decay curve is collected and the corresponding first curvature sequence is calculated. The first short-time power failure inertial coasting test is a conventional short-time power failure inertial coasting test.

[0073] S8200: After the first short-time power outage inertial coasting test is completed, the submersible motor is controlled to run stably at the initial detection speed for a fixed period of time.

[0074] S8300: When the submersible motor drive power is disconnected and the inverter output terminal is in the second electromagnetic state, the second short-time power failure inertial coasting test is performed, the second speed decay curve is collected and the corresponding second curvature sequence is calculated. The second short-time power failure inertial coasting test is a coasting test in which the inverter output terminal is short-circuited or the inverter is put into braking mode at the same time as the power is cut off.

[0075] S8400: Compare the first curvature sequence with the second curvature sequence to obtain the curvature feature differences, and determine the quantitative results of the electromagnetic residual contribution based on the curvature feature differences.

[0076] Specifically, the first electromagnetic state refers to the state where the inverter output terminals are in a normal open-circuit or high-impedance state after the submersible motor drive power supply is disconnected. In this state, the submersible motor experiences mechanical friction resistance and an electromagnetic braking effect generated by the motor's back electromotive force within the inverter's internal circuit during inertial gliding. The second electromagnetic state refers to the state where, simultaneously with the submersible motor drive power supply disconnected, the inverter output terminals are short-circuited or the inverter is put into braking mode. This aims to significantly alter or maximize the electromagnetic braking effect through external intervention, thereby providing a test condition with a clear electromagnetic difference from the first electromagnetic state.

[0077] The aforementioned first short-time power-off inertial coasting test was a conventional coasting test conducted under the first electromagnetic state. The acquired first speed decay curve and calculated first curvature sequence reflect the speed decay characteristics under the combined action of mechanical resistance and conventional electromagnetic braking. The aforementioned second short-time power-off inertial coasting test was a coasting test conducted under the second electromagnetic state. The acquired second speed decay curve and calculated second curvature sequence reflect the speed decay characteristics under the combined action of mechanical resistance and enhanced or specific electromagnetic braking.

[0078] After the first short-time power outage inertial coasting test is completed, the submersible motor is controlled to run stably at the initial detection speed for a fixed period of time. The purpose is to ensure that the mechanical and fluid operating state of the submersible motor can be restored to a stable condition similar to that at the beginning of the first test before the second short-time power outage inertial coasting test is performed, thereby minimizing the interference of non-electromagnetic factors between the two tests and ensuring the effectiveness of the control test.

[0079] By comparing the first curvature sequence and the second curvature sequence, the difference in curvature characteristics can be obtained. This difference mainly reflects the difference in electromagnetic braking effect under two different electromagnetic states. Based on this difference in curvature characteristics, the quantification result of the electromagnetic residual contribution can be determined, thus providing an accurate basis for subsequent correction of the scalar characteristics.

[0080] The proposed solution effectively separates the mechanical resistance and electromagnetic residual contribution during the inertial gliding process of a submersible motor by designing two comparative tests with clear differences in electromagnetic states.

[0081] In another embodiment of this application, a quantitative result for determining the electromagnetic residual contribution based on curvature characteristic differences is further proposed, specifically including:

[0082] S8410: Based on the initial speed detected before the start of the short-term power failure inertial gliding test of the current submersible motor, select the target speed range corresponding to the initial speed detected from the preset speed range library;

[0083] S8420: Extract typical curvature feature differences for the first and second electromagnetic states within the target speed range from the preset electromagnetic residual contribution feature database to obtain the reference curvature feature differences.

[0084] S8430: Collects real-time temperature and cumulative operating time of key inverter components;

[0085] S8440: Based on real-time temperature and cumulative running time, the difference in reference curvature characteristics is corrected to obtain the reference value of dynamic electromagnetic residual contribution under the current operating conditions;

[0086] S8450: Compares the curvature feature differences with the reference value of the dynamic electromagnetic residual contribution, and determines the quantitative result of the electromagnetic residual contribution based on the comparison results.

[0087] Specifically, the initial test speed refers to the stable operating speed of the submersible motor before performing a short-term power-off inertial coasting test; this speed is the starting point for the test. The speed range library can be understood as a pre-stored series of speed ranges, each corresponding to the typical operating characteristics of the submersible motor at different speed segments. By matching the current initial test speed with the speed range library, a most relevant target speed range can be determined. The electromagnetic residual contribution feature database stores typical curvature characteristic difference data obtained through extensive experiments or simulations under different speed ranges and electromagnetic states; this data constitutes the benchmark for electromagnetic residual contributions.

[0088] The real-time temperature of key inverter components refers to the current operating temperature of the core electronic components (such as IGBT modules and capacitors) inside the inverter that drive the submersible motor, while the cumulative operating time reflects the total operating time of the inverter since it was put into use. These parameters are key indicators affecting the electromagnetic characteristics and aging degree of the inverter. By collecting these parameters in real time and dynamically adjusting the differences in the reference curvature characteristics extracted from the database according to a preset correction model or algorithm, a dynamic electromagnetic residual contribution reference value that is more consistent with the current actual operating conditions is obtained. This correction process can take into account the influence of factors such as resistance changes caused by temperature rise and parameter drift caused by device aging on electromagnetic residuals.

[0089] In practical applications, the curvature characteristic differences obtained through control experiments are compared with the dynamically corrected reference value for electromagnetic residual contribution. This comparison is not a simple numerical comparison, but rather a comprehensive consideration of the deviation, trend, and statistical significance between the two. Based on the comparison results, the quantitative result of electromagnetic residual contribution under the current operating condition can be determined more accurately. For example, if the actual curvature characteristic difference is significantly higher than the dynamic reference value, it may mean that in addition to normal electromagnetic residual, there are other abnormal factors influencing the situation.

[0090] The proposed solution achieves dynamic correction of the quantification results of electromagnetic residual contribution by incorporating considerations of the initial detection speed, real-time temperature of key inverter components, and cumulative operating time.

[0091] In some preferred embodiments, it is assumed that a submersible motor is performing oil pumping operations downhole in an oil field. Before performing a short-term power outage inertial coasting test, the submersible motor is running stably at an initial detection speed of 1500 rpm. The system first matches a target speed range of "1400 rpm-1600 rpm" from a preset speed range library based on this initial detection speed of 1500 rpm. Subsequently, it extracts the typical curvature feature differences within this target speed range for conventional testing (first electromagnetic state) and inverter short-circuit testing (second electromagnetic state) from an electromagnetic residual contribution feature database to obtain the reference curvature feature differences.

[0092] Meanwhile, the system continuously monitors the real-time temperature of the inverter's IGBT module, which is 85℃, and checks that the inverter's cumulative operating time has reached 50,000 hours. Based on these real-time temperatures and cumulative operating times, the system applies a preset correction algorithm (e.g., for every 10℃ increase in temperature, the electromagnetic residual contribution reference value increases by X%; for every 10,000 hours increase in cumulative operating time, the electromagnetic residual contribution reference value increases by Y%) to correct for differences in the reference curvature characteristics, thereby obtaining a more accurate dynamic electromagnetic residual contribution reference value under the current operating conditions.

[0093] Assume the curvature characteristic difference actually measured through a control experiment is ΔK_actual. The system compares ΔK_actual with the dynamic electromagnetic residual contribution reference value ΔK_dynamic_ref. If ΔK_actual and ΔK_dynamic_ref are highly consistent, the current electromagnetic residual contribution is considered normal; if ΔK_actual is significantly higher than ΔK_dynamic_ref, it may indicate the presence of other abnormal resistances besides electromagnetic residuals, such as slight solid entanglement. Through this dynamic correction and comparison mechanism, even under conditions of long-term operation of the submersible motor leading to inverter aging or significant changes in ambient temperature, the electromagnetic residual contribution can be accurately quantified, avoiding misjudgments caused by changes in environmental factors.

[0094] In another embodiment of this application, S8450 is further proposed to include:

[0095] S8451: In the first short-time power failure inertial coasting test and the second short-time power failure inertial coasting test, the corresponding rotation speed data are collected respectively, and the first curvature sequence and the second curvature sequence are obtained based on the rotation speed data respectively.

[0096] S8452: Within a preset early time window after the start of the first short-time power outage inertial coasting test and the second short-time power outage inertial coasting test, calculate the first curvature instantaneous rate of change sequence and the second curvature instantaneous rate of change sequence respectively based on the first curvature sequence and the second curvature sequence.

[0097] S8453: Compare the first instantaneous rate of change sequence of curvature with the second instantaneous rate of change sequence of curvature to obtain the difference in instantaneous rate of change of curvature. Then, perform transient correction on the difference in curvature characteristics based on the difference in instantaneous rate of change of curvature to obtain the corrected difference in curvature characteristics, so as to deduct the influence of transient electromagnetic residual contribution on the speed decay curve.

[0098] S8454: Monitors the voltage and current waveforms at the inverter output terminals at the moment of power failure and extracts the transient characteristics of the voltage and current waveforms.

[0099] S8455: Cross-validate the difference between transient characteristics and instantaneous rate of change of curvature, and based on the cross-validation results, compare the corrected difference in curvature characteristics with the reference value of dynamic electromagnetic residual contribution, and determine the quantitative result of electromagnetic residual contribution.

[0100] Specifically, in the first and second short-duration power-off inertial coasting tests, it is necessary to collect the rotational speed data of the submersible motor during the inertial coasting process. This rotational speed data is the basis for subsequent calculations of the curvature sequence. The first and second curvature sequences represent the changes in the curvature of the speed decay curve under two different electromagnetic states. The preset early time window refers to a relatively short time interval in the initial stage of the speed decay curve after the start of the short-duration power-off inertial coasting test. Within this time window, the electromagnetic transient effect is usually most significant. The first and second instantaneous rate of change sequences of curvature refer to the rate of change of curvature over time within their respective early time windows, reflecting the intensity and duration of the electromagnetic transient effect.

[0101] In practical applications, transient correction aims to eliminate or reduce the impact of transient electromagnetic residual contributions on curvature characteristic differences. By comparing the instantaneous rate of change of curvature sequences under two electromagnetic states, the transient electromagnetic residual contribution can be quantified and subtracted from the original curvature characteristic differences, resulting in a purer and more accurate corrected curvature characteristic difference. Furthermore, monitoring the voltage and current waveforms at the inverter output terminals at the moment of power failure and extracting their transient characteristics aims to directly obtain evidence of electromagnetic transient effects at the electrical level. Transient characteristics can include parameters such as the peak value of voltage or current, decay time constant, and oscillation frequency.

[0102] Furthermore, cross-validation is performed between transient characteristics and the difference in the instantaneous rate of change of curvature. The aim is to improve the reliability of the quantification results of electromagnetic residual contribution by cross-verifying data from multiple sources. For example, if the electrical transient characteristics show a strong electromagnetic transient effect, and the difference in the instantaneous rate of change of curvature also shows a corresponding change, the confidence in the transient correction results can be enhanced. Based on the cross-validation results, the corrected difference in curvature characteristics is compared with the reference value of dynamic electromagnetic residual contribution, and the quantification result of the electromagnetic residual contribution is finally determined, thereby ensuring the accuracy of the quantification results.

[0103] The solution proposed in this application addresses the issue of the impact of transient electromagnetic residual contribution on the accuracy of the quantification results of electromagnetic residual contribution, which may exist in the above-mentioned solutions, by introducing a refined analysis and correction of the transient electromagnetic effect in the initial stage of power failure of the submersible motor.

[0104] In another embodiment of this application, a method for transiently correcting curvature feature differences based on differences in the instantaneous rate of change of curvature is further proposed, comprising:

[0105] S8453-1: After stable operation at multiple initial detection speeds, disconnect the submersible motor drive power supply and perform a short-time power-off inertial gliding test. Record the corresponding multiple speed decay curves and their curvature change trends to obtain the fluid baseline characteristics corresponding to each initial detection speed.

[0106] S8453-2: In the actual short-term power failure inertial coasting test, the rotational speed and its corresponding curvature are monitored in real time to obtain the real-time curvature change trend;

[0107] S8453-3: Compare the real-time curvature change trend with the fluid baseline characteristics, determine the fluid curvature components in the real-time curvature change trend that are consistent with the fluid baseline characteristics and the curvature components that deviate from the fluid baseline characteristics, and calculate the curvature characteristic differences corresponding to the deviating curvature components.

[0108] S8453-4: The deviation curvature component is attributed to the contribution of electromagnetic residual. The difference in the instantaneous rate of change of curvature is applied to the difference in curvature characteristics corresponding to the deviation curvature component for transient correction. The difference in curvature characteristics corresponding to the fluid curvature component is retained without correction, and the corrected curvature characteristic difference is obtained.

[0109] Specifically, fluid baseline characteristics refer to the inherent and stable fluid dynamic behavior exhibited by the speed decay curve and curvature change trend of a submersible motor during short-term power-off inertial coasting tests at different initial test speeds under known fluid properties and environmental conditions. These baseline characteristics are obtained by disconnecting the submersible motor drive power and performing inertial coasting tests in a controlled environment after stable operation at multiple preset initial test speeds. By recording the speed decay curves and curvature change trends at different initial speeds, a fluid behavior reference model covering different shear rate ranges can be established.

[0110] During actual short-term power outage inertial coasting tests, the system monitors the submersible motor's rotational speed and its corresponding curvature in real time, thereby obtaining the current real-time curvature change trend. This real-time curvature change trend is then compared with pre-established fluid baseline characteristics. The purpose of this comparison is to decompose the observed curvature change trend into two parts: one part is the fluid curvature component consistent with the fluid baseline characteristics, representing the expected behavior of the submersible motor interacting with the yielding pseudoplastic fluid under the current operating conditions; the other part is the curvature component deviating from the fluid baseline characteristics, representing the difference between the actual observation and the expected fluid behavior. The curvature characteristic difference corresponding to this deviation curvature component is calculated.

[0111] The deviation from the curvature component is attributed to electromagnetic residual contribution. This means that any transient curvature change that deviates from the fluid's inherent behavior is considered to be caused by electromagnetic residual effects. Therefore, transient correction is applied to the curvature characteristic difference corresponding to this deviation component using the difference in the instantaneous rate of change of curvature. The curvature characteristic difference corresponding to the fluid curvature component consistent with the fluid baseline characteristics is not corrected to ensure that the fluid's inherent dynamic properties are preserved. In this way, a more accurate corrected curvature characteristic difference can be obtained.

[0112] The solution proposed in this application effectively separates the inherent hydrodynamic behavior of a submersible motor operating in a yielding pseudoplastic fluid from the transient effects caused by electromagnetic residual contributions by establishing fluid baseline characteristics.

[0113] As a specific implementation method, it is assumed that the submersible motor operates in a specific yield pseudoplastic drilling fluid. First, in a laboratory or controlled environment, the submersible motor is stably operated at multiple initial test speeds (e.g., 1000 RPM, 1500 RPM, 2000 RPM), and a short-term power-off inertial coasting test is performed. The corresponding speed decay curves and curvature change trends are recorded respectively, thereby establishing the fluid baseline characteristics of the drilling fluid at different shear rates. For example, at 1500 RPM, a typical speed decay curve and corresponding curvature change trend are recorded as the fluid baseline characteristics at that speed.

[0114] In actual oil well operations, after the submersible motor has stabilized at 1500 RPM, a short-term power-off inertial coasting test is performed. During this test, the system collects rotational speed data in real time and calculates the real-time curvature change trend. This real-time curvature change trend is compared with the previously established fluid baseline characteristics at 1500 RPM. If the real-time curvature change trend differs from the fluid baseline characteristics, for example, if additional transient fluctuations occur in the early window, this difference is identified as a curvature deviation component. The system calculates the curvature characteristic difference corresponding to this deviation component and attributes it to electromagnetic residual contribution. Subsequently, a preset instantaneous rate of change of curvature difference is used to transiently correct the curvature characteristic difference corresponding to the deviation component, while the portion of the fluid baseline characteristics consistent with the fluid curvature component is not corrected. Finally, a precisely corrected curvature characteristic difference is obtained, which more accurately reflects the impact of non-fluid factors (such as solid entanglement) on the submersible motor's operation.

[0115] In another embodiment of this application, step S8453-1 is further proposed to include:

[0116] S8453-11: Collect current fluid concentration parameters and current ambient temperature;

[0117] S8453-12: Based on the current fluid concentration parameters and the current ambient temperature, dynamically generate a set of initial rotation speed sequences covering the range from low shear rate to high shear rate;

[0118] S8453-13: Control the submersible motor to run stably according to the detection initial speed sequence, and monitor the transient fluctuations of the submersible motor speed and torque at each detection initial speed in the detection initial speed sequence;

[0119] S8453-14: When the amplitude of transient fluctuation is stable within the preset fluctuation threshold for a preset duration, a short-term power-off inertial coasting test is performed at the corresponding initial detection speed, and the speed decay curve and curvature change trend of the short-term power-off inertial coasting test are recorded as fluid baseline characteristics corresponding to the initial detection speed.

[0120] S8453-15: If the amplitude of transient fluctuation does not reach the preset fluctuation threshold within the preset duration, the stable running time at the current detection initial speed shall be extended and / or the subsequent detection initial speed sequence shall be adjusted.

[0121] Specifically, collecting current fluid concentration parameters and current ambient temperature refers to obtaining information on the concentration of the fluid and the temperature of the environment around the submersible motor through sensors or other detection methods. These parameters have a significant impact on the rheological properties of yielding pseudoplastic fluids and are important bases for dynamically generating the initial rotational speed sequence for detection. For example, fluid concentration can be measured in real time using an online density meter or spectrometer, while ambient temperature can be collected using a temperature sensor.

[0122] Specifically, based on the current fluid concentration parameters and ambient temperature, a sequence of initial detection speeds covering a range from low to high shear rates is dynamically generated. This can be understood as the system intelligently planning a series of speed points for baseline testing based on the current actual operating conditions. These speed points should represent various shear rate conditions that the submersible motor may encounter in actual operation, thereby ensuring the universality of the obtained fluid baseline characteristics. For example, a speed range can be preset, and based on the fluid concentration and temperature, specific speed values ​​within this range can be selected as the initial detection speeds, as well as the intervals between these speed values, using a lookup table method or a machine learning-based model.

[0123] In practical applications, the submersible motor is controlled to operate stably according to a sequence of initial detection speeds. Monitoring the transient fluctuations of the motor's speed and torque at each initial detection speed within this sequence means that after the motor reaches each preset initial detection speed, the system does not immediately perform an inertial coasting test, but continuously monitors the minute changes in the motor's speed and torque. These transient fluctuations can reflect the dynamic evolution of the fluid's internal structure, such as the formation and destruction of the internal network structure of a yielding pseudoplastic fluid under shear stress. Speed ​​fluctuations can be monitored using high-precision encoders or Hall effect sensors, while torque fluctuations can be estimated using torque sensors or based on a motor current-voltage model.

[0124] Furthermore, when the amplitude of the transient fluctuation remains stable within a preset fluctuation threshold for a preset duration, a short-term power-off inertial coasting test is performed at the corresponding initial detection speed. The speed decay curve and curvature change trend of the short-term power-off inertial coasting test are recorded as the fluid baseline characteristics corresponding to the initial detection speed. This indicates that the system determines whether the fluid has reached a quasi-steady rheological state by judging the stability of the transient fluctuation. The preset fluctuation threshold and preset duration are parameters determined based on experience or experiments, used to define what degree of fluctuation is considered stable. For example, the fluctuation amplitude can be defined as the peak-to-peak value or standard deviation of the speed or torque within a certain time window. When this value is below a certain threshold and persists for a period of time, the fluid is considered to have reached a quasi-steady state.

[0125] In a preferred implementation, if the amplitude of the transient fluctuation does not reach a preset fluctuation threshold within a preset duration, the stabilization time at the current initial detection speed is extended, and / or the subsequent initial detection speed sequence is adjusted. This means the system has adaptive adjustment capabilities. If the fluid fails to stabilize at the current speed for an extended period, the system can attempt to extend the stabilization time, giving the fluid more time to reach a quasi-steady state; or, if it is determined that the current speed is not suitable for rapid stabilization, the system can adjust the subsequent initial detection speed sequence, for example, skipping the current speed or adjusting to a speed that is easier to stabilize, to optimize the efficiency and accuracy of baseline feature acquisition.

[0126] The solution proposed in this application solves the problem of accurately judging the rheological state of yield pseudoplastic fluid when acquiring fluid baseline characteristics by introducing the acquisition of fluid concentration parameters, ambient temperature, and monitoring of transient fluctuations in submersible motor speed and torque.

[0127] In some preferred embodiments, this application is implemented as follows:

[0128] Assume the submersible motor operates in a drilling fluid containing a high-molecular-weight polymer, exhibiting pronounced yield pseudoplastic fluid characteristics. First, the system uses online sensors to acquire the current drilling fluid concentration parameters: 1.2 g / cm³, and the ambient temperature: 60°C. Based on these parameters, the control system dynamically generates a sequence of initial rotational speeds, such as 500 rpm, 750 rpm, 1000 rpm, 1250 rpm, and 1500 rpm, using a pre-established rheological model or lookup table method. This sequence of speeds aims to cover the low to high shear rate range that the drilling fluid may experience at this concentration and temperature.

[0129] Next, the submersible motor is controlled to operate stably at 500 rpm. During this period, the system continuously monitors the transient fluctuations of the motor's speed and torque. For example, speed data is collected through a high-precision encoder, and torque data is collected through a torque sensor. The system sets preset fluctuation thresholds of less than ±5 rpm for speed fluctuation and less than ±0.5 Nm for torque fluctuation, with a preset duration of 30 seconds. If, after 20 seconds of operation, the speed fluctuation is still ±10 rpm and the torque fluctuation is ±1.0 Nm, the system determines that the fluid has not yet reached a quasi-steady state. At this time, the system extends the stable operation time at 500 rpm, for example, by another 30 seconds. If, after the extension, the speed fluctuation drops to ±3 rpm and the torque fluctuation drops to ±0.3 Nm, and this continues for 35 seconds, the system determines that the fluid has reached a quasi-steady rheological state. At this point, the submersible motor drive power is immediately disconnected, a short-term power-off inertial coasting test is performed, and the speed decay curve and its curvature change trend are recorded as the fluid baseline characteristics corresponding to 500 rpm.

[0130] Subsequently, the system repeats the above process sequentially at subsequent speeds such as 750 rpm and 1000 rpm. If, at 1250 rpm, even with extended stabilization time, the transient fluctuation amplitude consistently fails to reach the preset threshold (e.g., remaining above ±8 rpm), the system may determine that the fluid is unlikely to stabilize quickly at the current speed and adjust the initial speed sequence for subsequent tests. This could involve skipping 1250 rpm and directly testing at 1500 rpm, or adjusting the testing strategy at 1500 rpm to ensure reliable baseline data is obtained within a reasonable timeframe. This dynamic adjustment and rigorous stability assessment ensure that the obtained fluid baseline characteristics accurately reflect the true rheological resistance of the drilling fluid at different shear rates, thus providing a solid foundation for subsequent fault diagnosis.

[0131] In another embodiment of this application, it is further proposed that after monitoring the transient fluctuations of the submersible motor speed and torque, the transient fluctuations are decomposed into multiple scales and the fluctuation components in different frequency ranges are identified, thereby more accurately determining whether the yield pseudoplastic fluid has reached a quasi-steady rheological state.

[0132] Optionally, after monitoring the transient fluctuations in the submersible motor's speed and torque, the process includes:

[0133] S8453-131: Perform multi-scale decomposition on transient fluctuations to obtain transient fluctuation components covering different frequency ranges;

[0134] S8453-132: Identify low-frequency broadband wave components related to the rheological properties of yield pseudoplastic fluids, as well as specific high-frequency narrowband wave components related to sensor noise, electromagnetic interference, or mechanical vibration in transient wave components.

[0135] S8453-133: Based on the energy ratio and / or fluctuation amplitude difference between the low-frequency broadband fluctuation component and the specific high-frequency narrowband fluctuation component, determine whether the yield pseudoplastic fluid at the corresponding initial detection speed has reached a quasi-steady rheological state, including: when the low-frequency broadband fluctuation component is dominant and its fluctuation amplitude remains stable within a preset fluctuation threshold for a preset duration, determine that the yield pseudoplastic fluid has reached a quasi-steady rheological state; when the specific high-frequency narrowband fluctuation component is dominant or the fluctuation amplitude of the low-frequency broadband fluctuation component does not remain stable within a preset fluctuation threshold for a preset duration, determine that the yield pseudoplastic fluid has not reached a quasi-steady rheological state.

[0136] Multi-scale decomposition of transient fluctuations can be understood as using signal processing techniques to decompose the original transient fluctuation signal into components within different time scales or frequency ranges. Specifically, methods such as wavelet transform, empirical mode decomposition (EMD), or variational mode decomposition (VMD) can be employed. The aim is to separate complex transient fluctuation signals into more easily analyzed components, thereby distinguishing fluctuations from different sources.

[0137] Furthermore, the low-frequency broadband fluctuation components identified in the transient fluctuation components refer to fluctuation components with lower frequencies and a wider frequency range. These are typically closely related to the rheological properties of yield pseudoplastic fluids under shear, such as internal structural evolution, shear thinning, and thixotropy. The speed and torque fluctuations caused by these fluid characteristics often exhibit slow and prolonged changes. Conversely, specific high-frequency narrow-band fluctuation components typically refer to fluctuation components with higher frequencies and a narrower frequency range. These mainly originate from non-fluid factors such as sensor noise, external electromagnetic interference, and mechanical vibrations within the submersible motor or pump body. The purpose is to distinguish the dynamic response of the fluid itself from external interference or measurement errors.

[0138] In practical applications, the energy ratio and / or amplitude difference between the low-frequency broadband fluctuation component and a specific high-frequency narrowband fluctuation component are used to determine whether a yielding pseudoplastic fluid has reached a quasi-steady rheological state. Specifically, the energy ratio refers to the ratio of the energy of the low-frequency broadband fluctuation component to that of the specific high-frequency narrowband fluctuation component, or the proportion of the low-frequency broadband fluctuation component's energy to the total fluctuation energy. The amplitude difference refers to the difference between the peak-to-peak value, root-mean-square value, or standard deviation of the two components. The purpose is to provide a quantitative indicator to assess the dominance and stability of fluid-related fluctuations in the overall transient fluctuation. When the low-frequency broadband fluctuation component significantly dominates in energy or amplitude, and its amplitude remains stable within a preset fluctuation threshold for a preset duration, it indicates that the fluid's rheological state has reached quasi-steady. Conversely, if the high-frequency narrowband fluctuation component dominates, or the low-frequency broadband fluctuation component is unstable, the fluid is considered not to have reached a quasi-steady state.

[0139] The proposed solution employs multi-scale decomposition of the transient fluctuations in the submersible motor's speed and torque. This effectively separates the low-frequency broadband fluctuation components associated with the rheological properties of yield pseudoplastic fluids from specific high-frequency narrow-band fluctuation components caused by sensor noise, electromagnetic interference, or mechanical vibration. This separation allows the system to more accurately determine whether the fluid has truly reached a quasi-steady rheological state based on the energy ratio or fluctuation amplitude differences of the different frequency components. This refined analysis avoids misjudgments that might arise from relying solely on overall fluctuation amplitude, ensuring that subsequent inertial gliding tests are conducted under truly stable fluid conditions.

[0140] In some preferred embodiments, a specific example is given below. Assume that when monitoring transient fluctuations in the speed and torque of a submersible motor, wavelet transform is used to decompose the acquired signal into multiple scales. By analyzing the wavelet coefficients at different scales, a low-frequency broadband fluctuation component corresponding to the 0.1Hz to 1Hz frequency range can be identified. This fluctuation is considered to primarily reflect the structural evolution and rheological properties of the yielding pseudoplastic fluid. Simultaneously, a specific high-frequency narrowband fluctuation component corresponding to the 50Hz to 100Hz frequency range is identified. This fluctuation is attributed to power supply harmonics, high-frequency sensor noise, or motor mechanical vibration. Subsequently, the energy ratio of the low-frequency broadband fluctuation component to the high-frequency narrowband fluctuation component is calculated. If this energy ratio is consistently higher than a preset threshold (e.g., the low-frequency energy is more than 5 times the high-frequency energy), and the fluctuation amplitude of the low-frequency broadband fluctuation component itself remains stable within a very small preset fluctuation threshold (e.g., speed fluctuation less than 0.1rpm) for a preset duration (e.g., 30 seconds) over a continuous monitoring period, then the yielding pseudoplastic fluid is determined to have reached a quasi-steady rheological state. Conversely, if the energy of the high-frequency narrowband fluctuation component is dominant, or if the fluctuation amplitude of the low-frequency broadband fluctuation component fails to remain stably within the preset fluctuation threshold within the preset duration, it is determined that the fluid has not reached a quasi-steady rheological state, and it may be necessary to extend the stabilization operation time or adjust the initial detection speed.

[0141] In another embodiment of this application, S8453-14 further includes:

[0142] S8453-141: At each initial speed in the detection initial speed sequence, continuously monitor the fluctuation amplitude of transient fluctuations, and calculate the real-time mean and real-time variance of the fluctuation amplitude in each monitoring period;

[0143] S8453-142: When the real-time mean and real-time variance are both lower than the preset mean threshold and preset variance threshold in multiple consecutive monitoring periods, it is determined that the transient fluctuation at the corresponding initial speed of detection is in a short-term stable state.

[0144] S8453-143: After determining that the transient fluctuation is a short-term steady state, continue to monitor the fluctuation amplitude of the transient fluctuation and calculate the long-term trend slope of the fluctuation amplitude within the preset observation time window;

[0145] S8453-144: When the absolute value of the long-term trend slope is lower than the preset slope threshold and the duration of the short-term steady state exceeds the preset minimum steady duration, it is determined that the yield pseudoplastic fluid at the corresponding detection initial speed has reached the quasi-steady rheological state, and at this time, the speed decay curve and its curvature change trend of the short-term power failure inertial gliding test are recorded as the fluid baseline characteristics corresponding to the detection initial speed.

[0146] S8453-145: If the absolute value of the long-term trend slope exceeds the preset slope threshold range, it is determined that the yield pseudoplastic fluid has not reached the quasi-steady rheological state, and the monitoring time is extended and / or the preset minimum stability duration is adjusted before re-determining the stability.

[0147] Specifically, at each initial speed in the detection sequence, the system continuously monitors the transient fluctuations of the submersible motor's speed and torque. The amplitude of the transient fluctuation refers to the range of change in speed or torque over a short period, or the degree of deviation from its average value. During monitoring, the system calculates the real-time mean and variance of the fluctuation amplitude within a preset monitoring period (e.g., every second or every few seconds). The real-time mean reflects the central trend of the fluctuation amplitude, while the real-time variance reflects the degree of dispersion of the fluctuation amplitude.

[0148] The preset mean threshold and preset variance threshold are pre-set based on empirical data or system design requirements, and are used to define whether the fluctuation amplitude is sufficiently small and stable in the short term. When the real-time mean and real-time variance are both lower than these preset thresholds in multiple consecutive monitoring periods, it indicates that the transient fluctuation exhibits good stability in the short term, and the system determines that the transient fluctuation at the corresponding initial rotational speed is in a short-term stable state.

[0149] In practical applications, after determining that a transient fluctuation is a short-term steady state, the system continues to monitor the amplitude of the transient fluctuation to further confirm the long-term stability of the fluid. Within a preset observation time window, the long-term trend slope of the fluctuation amplitude is calculated using linear regression or other trend analysis methods. The long-term trend slope is used to assess whether the fluctuation amplitude exhibits a sustained upward or downward trend over a longer time scale.

[0150] In a preferred implementation, when the absolute value of the long-term trend slope is lower than a preset slope threshold, it indicates that the fluctuation amplitude has not shown a significant trend change over the long term. Simultaneously, if the duration of the short-term steady state exceeds a preset minimum steady-state duration, it is determined that the yielding pseudoplastic fluid has reached a quasi-steady rheological state. Under this condition, the system immediately performs a short-term power-off inertial gliding test and records its rotational speed decay curve and its curvature change trend as the fluid baseline characteristic corresponding to the initial detection rotational speed.

[0151] Furthermore, if the absolute value of the long-term trend slope exceeds the preset slope threshold range, even if the fluctuation amplitude appears stable in the short term, it indicates that the fluid has not yet reached a true quasi-steady rheological state. In this case, the system will determine that the yielding pseudoplastic fluid has not reached a quasi-steady rheological state and take measures, such as extending the monitoring time at the current initial detection speed or adjusting the subsequent initial detection speed sequence, in order to re-determine the stability under more stable conditions.

[0152] The solution proposed in this application effectively solves the problem of misjudging the quasi-steady rheological state of fluids that may be caused by simple threshold judgment in the prior art by introducing a multi-stage and multi-dimensional stability determination mechanism.

[0153] In some preferred embodiments, a specific example is given below. Assume the submersible motor is operating at a certain initial detection speed, and the system begins monitoring the transient fluctuations in its speed and torque.

[0154] First, the system continuously calculates the real-time mean and real-time variance of the fluctuation amplitude at a monitoring cycle of one second. For example, the preset mean threshold is set to 0.5 rpm, and the preset variance threshold is set to 0.05 (rpm)^2. If the real-time mean is consistently below 0.5 rpm and the real-time variance is consistently below 0.05 (rpm)^2 for 10 consecutive monitoring cycles, the system determines that the transient fluctuation has entered a short-term stable state.

[0155] Secondly, after determining a short-term steady state, the system continues to monitor the fluctuation amplitude and calculates the average fluctuation amplitude every 10 seconds within a preset observation time window (e.g., 5 minutes), and calculates the long-term trend slope based on these averages. Assuming the preset slope threshold is set to 0.01 rpm / min and the preset minimum stable duration is 3 minutes, if the absolute value of the calculated long-term trend slope is less than 0.01 rpm / min within this 5-minute observation window, and the short-term steady state has lasted for more than 3 minutes, then the system determines that the yielding pseudoplastic fluid has reached a quasi-steady rheological state. At this point, the system immediately triggers a short-term power-off inertial gliding test and records the corresponding rotational speed decay curve and curvature change trend as the fluid baseline characteristics at the initial detection rotational speed.

[0156] Conversely, if the absolute value of the long-term trend slope exceeds 0.01 rpm / min, even if the fluctuation amplitude appears stable in the short term, the system will determine that the fluid has not reached a quasi-steady rheological state. In this case, the system may extend the monitoring time at the current initial detection speed, for example, by another 5 minutes, or adjust the initial detection speed sequence to find more stable operating conditions, and then repeat the above stability determination process. Through this phased, multi-index determination mechanism, the obtained fluid baseline characteristics can be ensured to have high accuracy and reliability.

[0157] Reference Figure 2 The specific embodiments of this application also disclose a submersible motor operation control system, including:

[0158] Operation control module 1 is used to control the submersible motor to run stably at a preset initial detection speed for a fixed period of time before performing a short-term power failure inertial gliding test;

[0159] The operation control module 1 is also used to perform a short-term power outage inertial gliding test on the submersible motor after stable operation, and to make quantitative judgments:

[0160] Data acquisition module 2 is used to continuously acquire the speed data of the submersible motor at a preset sampling frequency, and record the time point corresponding to each speed value to obtain the original data sequence of speed change over time.

[0161] Filtering module 3 is used to filter the original data sequence to obtain the rotational speed data sequence;

[0162] The parameter calculation module 4 is used to calculate the angular acceleration sequence and curvature sequence of the submersible motor during the inertial coasting process based on the speed data sequence and according to the preset sampling time interval, so as to obtain the speed decay curve.

[0163] The time window division module 5 is used to divide the speed decay curve into multiple time windows according to time. The multiple time windows include at least an early window, a transition window, and a tail window.

[0164] Feature extraction module 6 is used to extract at least two of the following as scalar features for each time window: mean curvature, curvature variance, relative rotational speed decay ratio, and linear residual ratio, based on the corresponding curvature sequence and angular acceleration sequence.

[0165] The electromagnetic residual deduction module 7 is used to perform a control test and compare the curvature characteristics under different test conditions to obtain the quantitative results of the electromagnetic residual contribution, and to correct the scalar characteristics based on the electromagnetic residual contribution. The control test includes at least one conventional short-time power-off inertial coasting test and one coasting test in which the inverter output terminals are short-circuited or the inverter is put into braking mode at the same time as the power is off.

[0166] The judgment rule module 8 is used to apply quantitative judgment rules based on the modified scalar characteristics. According to the quantitative judgment rules, by analyzing the curvature change trend in multiple time windows and the linearity characteristics of the rotational speed decay in the tail window, it distinguishes between the transient resistance caused by the evolution of the yield pseudoplastic fluid structure and the approximately constant mechanical friction generated by solid entanglement, and obtains the preliminary judgment results of the inertial gliding test.

[0167] The repeat test module 9 is used to perform a short-time power-off inertial gliding test again after a preset time interval when the preliminary judgment result indicates that there is approximately constant mechanical friction, and to repeat the quantitative judgment. When both of the previous and subsequent independent preliminary judgment results indicate that there is approximately constant mechanical friction, the final judgment result of approximately constant mechanical friction caused by solid winding is confirmed to be generated.

[0168] The response strategy module 10 is used to execute a graded response strategy based on the final judgment result. The graded response strategy includes at least controlling the submersible motor to perform short-term speed-up and / or alternating forward and reverse untangling, and executing a safety shutdown and issuing a fault alarm when the tangling cannot be untangled.

[0169] The submersible motor operation control system of this application achieves comprehensive monitoring and intelligent diagnosis of the submersible motor's operating status through a modular design. This system can coordinate various functional modules to extract key features from the submersible motor's inertial coasting test data and perform refined analysis, thereby accurately distinguishing between transient resistance caused by fluid characteristics and approximately constant mechanical friction generated by solid entanglement. By introducing a quantification and correction mechanism for electromagnetic residual contributions, the accuracy of the diagnosis is further improved. Finally, the system can execute a graded response strategy based on the diagnostic results, effectively avoiding blind spots in traditional monitoring methods and significantly improving the reliability and safety of the submersible motor's operation.

[0170] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method of operating control of a submersible motor, characterized by, The method comprises the following steps: Before performing the short-time power-off inertia coast-down test, the submersible motor is controlled to stably operate at a preset detection initial rotating speed for a fixed time; After stable operation, the submersible motor starts the short-time power-off inertia coast-down test and performs quantitative determination: At a preset sampling frequency, the rotating speed data of the submersible motor are continuously collected, and the time point corresponding to each rotating speed value is recorded to obtain an original data sequence of the change of the rotating speed with time; The original data sequence is filtered to obtain a rotating speed data sequence; Based on the rotating speed data sequence, the angular acceleration sequence and the curvature sequence of the submersible motor in the inertia coast-down process are calculated according to a preset sampling time interval to obtain a rotating speed decay curve; The rotating speed decay curve is divided into a plurality of time windows according to time, and the plurality of time windows at least include an early window, a transition window and a tail window; For each time window, at least two of the curvature mean value, the curvature variance, the rotating speed relative decay ratio and the linear residual ratio in the time window are extracted as scalar features based on the corresponding curvature sequence and angular acceleration sequence; A contrast test is performed and the curvature feature differences under different test conditions are compared to obtain a quantitative result of the electromagnetic residual contribution, and the scalar features are corrected based on the electromagnetic residual contribution, and the contrast test at least includes one conventional short-time power-off inertia coast-down test and one coast-down test in which the output terminals of the inverter are short-circuited or the inverter is in a braking mode during power-off; Based on the corrected scalar features, a quantitative determination rule is applied, the curvature change trend in the plurality of time windows and the linearity feature of the rotating speed decay in the tail window are analyzed according to the quantitative determination rule, the transient resistance caused by the evolution of the yield pseudoplastic fluid structure is distinguished from the approximately constant mechanical friction caused by the solid entanglement to obtain a preliminary determination result of the inertia coast-down test; When the preliminary determination result represents that there is approximately constant mechanical friction, the short-time power-off inertia coast-down test is performed again after a preset time interval, and the quantitative determination is repeated, and when the preliminary determination results of the two independent times both represent that there is approximately constant mechanical friction, a final determination result that there is approximately constant mechanical friction caused by solid entanglement is confirmed to be generated; According to the final determination result, a hierarchical response strategy is performed, and the hierarchical response strategy at least includes controlling the submersible motor to perform short-time speed-up throwing and / or positive and negative rotation alternating disentanglement, and performing safe shutdown and issuing a fault alarm when the entanglement cannot be removed.

2. The submerged motor operation control method according to claim 1, characterized by, Based on the corrected scalar features, a quantitative determination rule is applied, the curvature change trend in the plurality of time windows and the linearity feature of the rotating speed decay in the tail window are analyzed according to the quantitative determination rule, the transient resistance caused by the evolution of the yield pseudoplastic fluid structure is distinguished from the approximately constant mechanical friction caused by the solid entanglement to obtain a preliminary determination result of the inertia coast-down test, including: The environmental temperature and the concentration parameter of the yield pseudoplastic fluid are collected; The historical operating rotating speed of the submersible motor within a preset time length before the short-time power-off inertia coast-down test is collected; According to the ambient temperature, the concentration parameter and the historical running speed, a judgment threshold for evaluating the curvature change trend in the plurality of time windows and the speed decay linearity feature of the tail window is dynamically adjusted; Based on the corrected scalar feature and the dynamically adjusted judgment threshold, by analyzing the curvature change trend in the plurality of time windows and the speed decay linearity feature of the tail window, the transient resistance caused by the yield pseudoplastic fluid structure evolution is distinguished from the approximately constant mechanical friction caused by the solid winding, and the preliminary judgment result is obtained.

3. The operation control method of a submersible motor according to claim 1, characterized by, A control test is performed and the curvature feature difference under different test conditions is compared to obtain a quantitative result of electromagnetic residual contribution, including: When the submersible motor driving power is disconnected and the inverter output terminal is in the first electromagnetic state during the execution of the control test, a first short-time power-off inertia coasting test is performed, a first speed decay curve is collected, and a corresponding first curvature sequence is calculated, and the first short-time power-off inertia coasting test is a conventional short-time power-off inertia coasting test; After the first short-time power-off inertia coasting test is completed, the submersible motor is controlled to stably operate at the detection initial speed for a fixed time; When the submersible motor driving power is disconnected and the inverter output terminal is in the second electromagnetic state, a second short-time power-off inertia coasting test is performed, a second speed decay curve is collected, and a corresponding second curvature sequence is calculated, and the second short-time power-off inertia coasting test is a coasting test in which the inverter output terminal is short-circuited or the inverter is in a braking mode while being powered off; The first curvature sequence and the second curvature sequence are compared to obtain a curvature feature difference, and a quantitative result of the electromagnetic residual contribution is determined based on the curvature feature difference.

4. The submerged motor operation control method according to claim 3, characterized by, Based on the curvature feature difference, the quantitative result of the electromagnetic residual contribution includes: According to the detection initial speed of the current submersible motor before the start of the short-time power-off inertia coasting test, a target speed interval corresponding to the detection initial speed is selected from a pre-set speed interval library; From a pre-set electromagnetic residual contribution feature database, a typical curvature feature difference for the first electromagnetic state and the second electromagnetic state in the target speed interval is extracted to obtain a reference curvature feature difference; The real-time temperature of the key components of the inverter and the cumulative running time are collected; According to the real-time temperature and the cumulative running time, the reference curvature feature difference is corrected to obtain a dynamic electromagnetic residual contribution reference value under the current working condition; The curvature feature difference and the dynamic electromagnetic residual contribution reference value are compared, and a quantitative result of the electromagnetic residual contribution is determined based on the comparison result.

5. The operation control method of a submersible motor according to claim 4, characterized by, The curvature feature difference and the dynamic electromagnetic residual contribution reference value are compared, and a quantitative result of the electromagnetic residual contribution is determined based on the comparison result, including: In the first short-time power-off inertia coasting test and the second short-time power-off inertia coasting test, corresponding speed data are collected, and a first curvature sequence and a second curvature sequence are obtained based on the speed data, respectively; In a preset early time window after each of the first short-time power-off inertia coasting test and the second short-time power-off inertia coasting test starts, a first curvature instantaneous change rate sequence and a second curvature instantaneous change rate sequence are calculated according to the first curvature sequence and the second curvature sequence, respectively; The first curvature instantaneous change rate sequence and the second curvature instantaneous change rate sequence are compared to obtain a curvature instantaneous change rate difference, and the curvature feature difference is transiently corrected according to the curvature instantaneous change rate difference to obtain a corrected curvature feature difference, so as to eliminate the influence of the transient electromagnetic residual contribution on the speed decay curve; The voltage waveform and the current waveform of the output terminal of the inverter at the power-off moment are monitored, and transient features of the voltage waveform and the current waveform are extracted; The transient features and the curvature instantaneous change rate difference are cross-verified, and based on the cross-verification result, the corrected curvature feature difference is compared with the dynamic electromagnetic residual contribution reference value, and the quantitative result of the electromagnetic residual contribution is determined.

6. The submerged motor operation control method according to claim 5, characterized by, The transient correction of the curvature feature difference according to the curvature instantaneous change rate difference includes: After the submersible motor is stably operated at a plurality of detection initial speeds, the driving power supply of the submersible motor is disconnected, a short-time power-off inertia coasting test is performed, a plurality of speed decay curves and their curvature change trends corresponding to the plurality of detection initial speeds are recorded respectively, and fluid baseline features corresponding to the plurality of detection initial speeds are obtained; During the actual short-time power-off inertia coasting test, the speed and its corresponding curvature are monitored in real time to obtain a real-time curvature change trend; The real-time curvature change trend is compared with the fluid baseline features to determine a fluid curvature component consistent with the fluid baseline features and a deviated curvature component relative to the fluid baseline features in the real-time curvature change trend, and a curvature feature difference corresponding to the deviated curvature component is calculated; The deviated curvature component is attributed to electromagnetic residual contribution, the curvature feature difference corresponding to the deviated curvature component is transiently corrected by using the curvature instantaneous change rate difference, and the curvature feature difference corresponding to the fluid curvature component is not corrected to obtain a corrected curvature feature difference.

7. The submerged motor operation control method according to claim 6, characterized by, After the submersible motor is stably operated at a plurality of detection initial speeds, the driving power supply of the submersible motor is disconnected, a short-time power-off inertia coasting test is performed, a plurality of speed decay curves and their curvature change trends corresponding to the plurality of detection initial speeds are recorded respectively, and fluid baseline features corresponding to the plurality of detection initial speeds are obtained, including: The current fluid concentration parameter and the current environmental temperature are acquired; According to the current fluid concentration parameter and the current environmental temperature, a set of detection initial speed sequences covering a low shear rate to a high shear rate range are dynamically generated; The submersible motor is controlled to be stably operated according to the detection initial speed sequences, and the transient fluctuations of the speed and the torque of the submersible motor are monitored at each detection initial speed in the detection initial speed sequences; When the fluctuation amplitude of the transient fluctuation is stable within a preset fluctuation threshold for a preset duration, a short-time power-off inertia coast-down test is performed at the corresponding detection initial rotating speed, and the rotating speed attenuation curve and its curvature change trend of the short-time power-off inertia coast-down test are recorded as the fluid baseline characteristic corresponding to the detection initial rotating speed; If the fluctuation amplitude of the transient fluctuation does not reach the preset fluctuation threshold within the preset duration, the stable operation time at the current detection initial rotating speed is extended and / or the subsequent detection initial rotating speed sequence is adjusted.

8. The submerged motor operation control method according to claim 7, characterized by, After monitoring the transient fluctuation of the rotating speed and torque of the submersible motor, the method comprises: Performing multi-scale decomposition processing on the transient fluctuation to obtain transient fluctuation components covering different frequency ranges; Identifying, in the transient fluctuation components, a low-frequency broadband fluctuation component related to the rheological characteristics of the yield pseudoplastic fluid and a specific high-frequency narrowband fluctuation component related to sensor noise, electromagnetic interference or mechanical vibration; According to the energy ratio and / or fluctuation amplitude difference between the low-frequency broadband fluctuation component and the specific high-frequency narrowband fluctuation component, it is judged whether the yield pseudoplastic fluid at the corresponding detection initial rotating speed reaches a quasi-stable rheological state, comprising: when the low-frequency broadband fluctuation component is dominant and its fluctuation amplitude is stable within a preset fluctuation threshold for a preset duration, it is determined that the yield pseudoplastic fluid reaches a quasi-stable rheological state; when the specific high-frequency narrowband fluctuation component is dominant or the fluctuation amplitude of the low-frequency broadband fluctuation component does not remain stable within the preset fluctuation threshold within the preset duration, it is determined that the yield pseudoplastic fluid does not reach a quasi-stable rheological state.

9. The submerged motor operation control method according to claim 7, characterized by, The fluctuation amplitude of the transient fluctuation is stable within a preset fluctuation threshold for a preset duration, comprising: At each detection initial rotating speed in the detection initial rotating speed sequence, the fluctuation amplitude of the transient fluctuation is continuously monitored, and the real-time mean and real-time variance of the fluctuation amplitude within each monitoring period are calculated; When the real-time mean and the real-time variance are lower than the preset mean threshold and the preset variance threshold in continuous multiple monitoring periods, it is determined that the transient fluctuation at the corresponding detection initial rotating speed is in a short-term stable state; After determining that the transient fluctuation is in a short-term stable state, the fluctuation amplitude of the transient fluctuation is continuously monitored, and the long-term trend slope of the fluctuation amplitude is calculated within a preset observation time window; When the absolute value of the long-term trend slope is lower than the preset slope threshold, and the duration of the short-term stable state exceeds the preset minimum stable duration, it is determined that the yield pseudoplastic fluid at the corresponding detection initial rotating speed reaches a quasi-stable rheological state, and at this time the rotating speed attenuation curve and its curvature change trend of the short-time power-off inertia coast-down test are recorded as the fluid baseline characteristic corresponding to the detection initial rotating speed; If the absolute value of the long-term trend slope exceeds the range of the preset slope threshold, it is determined that the yield pseudoplastic fluid does not reach a quasi-stable rheological state, and the monitoring time is extended and / or the preset minimum stable duration is adjusted before the stability is determined again.

10. A submersible motor operation control system characterized by comprising: Comprise: The running control module is configured to control the submersible motor to stably run at a preset detection initial rotating speed for a fixed time before performing the short-time power-off inertia coast-down test. The running control module is further configured to start the short-time power-off inertia coast-down test and perform quantitative determination after the stable running of the submersible motor. The data acquisition module is configured to continuously acquire rotating speed data of the submersible motor at a preset sampling frequency, record a time point corresponding to each rotating speed value, and obtain an original data sequence of the rotating speed changing with time. The filtering processing module is configured to filter the original data sequence to obtain a rotating speed data sequence. The parameter calculation module is configured to calculate, based on the rotating speed data sequence, an angular acceleration sequence and a curvature sequence of the submersible motor in the inertia coast-down process according to a preset sampling time interval, and obtain a rotating speed decay curve. The time window division module is configured to divide the rotating speed decay curve into a plurality of time windows according to time, and the plurality of time windows at least include an early window, a transition window and a tail window. The feature extraction module is configured to, for each time window, extract at least two of a curvature mean value, a curvature variance, a rotating speed relative attenuation ratio and a linear residual ratio in the time window as scalar features based on the corresponding curvature sequence and angular acceleration sequence. The electromagnetic residual deduction module is configured to perform a contrast test and compare the curvature feature differences under different test conditions to obtain a quantitative result of electromagnetic residual contribution, and correct the scalar features based on the electromagnetic residual contribution, wherein the contrast test at least includes a regular short-time power-off inertia coast-down test and a coast-down test in which the output terminals of the inverter are short-circuited or the inverter is in a braking mode. The determination rule module is configured to, based on the corrected scalar features, apply a quantitative determination rule to analyze the curvature change trend in the plurality of time windows and the rotating speed decay linearity feature of the tail window according to the quantitative determination rule, distinguish the transient resistance caused by the yield pseudoplastic fluid structure evolution from the approximately constant mechanical friction caused by the solid winding, and obtain a preliminary determination result of the inertia coast-down test. The repeated test module is configured to, when the preliminary determination result represents that there is approximately constant mechanical friction, perform a short-time power-off inertia coast-down test again after a preset time interval, and repeatedly perform quantitative determination, and when both the preliminary determination results of the two independent tests represent that there is approximately constant mechanical friction, confirm to generate a final determination result that there is approximately constant mechanical friction caused by the solid winding. The response strategy module is configured to perform a hierarchical response strategy according to the final determination result, wherein the hierarchical response strategy at least includes controlling the submersible motor to perform short-time speed-up throwing and / or positive and negative rotation alternating unwinding, and performing safe shutdown and issuing a fault alarm when the winding cannot be unwound.

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