Asynchronous motor energy-saving monitoring and dynamic early warning method based on situation awareness

Abstract

The invention discloses an asynchronous motor energy-saving monitoring and dynamic early warning method based on situation awareness, and relates to the technical field of asynchronous motor energy-saving monitoring. The method comprises the steps that S1, multi-source heterogeneous data are synchronously collected, power supply parameters and operation parameters are obtained in real time, and a frequency conversion working condition self-adaptive deviation value and a current stability coefficient are obtained; s2, generating four-dimensional situation factors including an overtemperature danger value, a current stability coefficient, a voltage stability coefficient and a frequency deviation value; s3, constructing a fourth-order transmission network, and generating a primary early warning signal based on the path mark combination; s4, calculating the motor efficiency in real time, triggering an efficiency abnormity mark, fusing the efficiency abnormity mark with the primary early warning signal, and reconstructing a final early warning instruction; and S5, executing hierarchical control according to the final early warning instruction. Through multi-parameter coupling and dynamic early warning transmission, the early-stage capture capability of the composite fault is improved, the early warning response delay is shortened, energy-saving optimization and fault protection of the motor are realized, and the method has a remarkable practical value.

Description

Technical Field

[0001] This invention relates to the field of energy-saving monitoring technology for asynchronous motors, and more specifically, to a method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness. Background Technology

[0002] With the increasing demand for energy conservation in the industrial sector, the technology for energy efficiency monitoring and fault early warning of asynchronous motors continues to develop, and its energy efficiency and reliability directly affect the operating costs of production systems.

[0003] Traditional monitoring methods rely on regular manual inspections and fixed threshold alarms, which generally suffer from problems such as delayed response, incomplete coverage of operating conditions, and crude energy efficiency management. To improve this situation, online motor monitoring systems have emerged in the industry, which realize the functions of basic parameter acquisition and over-limit alarm. However, in practical applications, they still have the following defects: On the one hand, existing systems are mostly based on static rated parameters to design early warning rules, without integrating the real-time operating status of the motor and dynamic loss factors, resulting in a mismatch between early warning results and actual risks.

[0004] On the other hand, existing systems lack a multi-source risk collaborative decision-making mechanism when dealing with sudden changes in complex operating conditions; when encountering complex fault scenarios such as grid voltage dips, load step changes, or cooling system failures, they cannot dynamically reconstruct early warning strategies, thus delaying critical intervention opportunities. Summary of the Invention

[0005] To overcome the aforementioned deficiencies of the prior art, this invention provides a situational awareness-based method for energy-saving monitoring and dynamic early warning of asynchronous motors, which addresses the problems mentioned in the background section through the following approach.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness, comprising the following steps:

[0007] S1: Multi-source heterogeneous data synchronous acquisition: Real-time acquisition of power supply parameter data and operating parameter data of the target asynchronous motor to obtain the adaptive deviation value and current stability coefficient of variable frequency operation;

[0008] The power supply parameter data of the target asynchronous motor includes the voltage and power supply frequency at the motor power supply input terminal, and the operating parameter data includes the torque, speed, motor winding temperature, and three-phase current at the motor mechanical output terminal.

[0009] S2: Generate situation factors: Based on the multi-source heterogeneous data collected by S1, generate over-temperature hazard value, current stability coefficient, voltage stability coefficient and frequency deviation value, and construct a four-dimensional situation factor;

[0010] S3: Network dynamic early warning transmission: Construct a fourth-order transmission network corresponding to the four-dimensional situation factors, output path markers, and generate primary early warning signals based on the combination of fourth-order path markers;

[0011] S4: Energy efficiency fusion correction: Real-time calculation of motor efficiency. When the motor efficiency is less than the preset efficiency threshold, an efficiency anomaly flag is triggered. The efficiency anomaly flag and the primary warning signal are merged and reconstructed into the final warning command.

[0012] S5: Closed-loop control response: Execute hierarchical control according to the final warning command.

[0013] Preferably, the adaptive deviation value for variable frequency operation is obtained by coupling a high-frequency voltage sensor on the power supply cable between the circuit breaker and the motor stator to extract the zero-crossing distortion characteristics of the voltage waveform;

[0014] Record the time intervals between consecutive zero crossings of the voltage waveform, take the median of these time interval sequences, multiply the median by two and take the reciprocal to obtain the real-time operating frequency; the adaptive deviation value of this variable frequency operating condition is equal to the absolute value of the difference between the actual operating frequency and the system preset motor operating frequency, divided by the larger of the system preset frequency and 10Hz, and then multiplied by 100% to express the percentage deviation.

[0015] Preferably, the current stability coefficient is obtained by installing a three-channel Rogowski coil in the motor junction box, synchronously collecting the instantaneous values ​​of the three-phase current, and performing independent sliding statistical analysis on the current of each phase.

[0016] The window length is calculated based on the power supply frequency: divide the power supply frequency by 50, round the result to the nearest integer, and then multiply by 10. The window length is adaptively adjusted according to the fundamental frequency period. The fluctuation dispersion of each phase current is equal to the standard deviation of the instantaneous value sequence of the phase current divided by the average value of the phase current sequence. The fluctuation dispersion of phases A, B, and C are calculated separately. The current stability coefficient is obtained by subtracting the maximum value of the three-phase current fluctuation dispersion from 1.

[0017] Preferably, the torque is obtained by embedding a strain gauge torque flange between the motor output shaft and the load coupling to collect the original torque signal, and simultaneously by arranging a piezoelectric acceleration sensor on the same shaft section of the torque flange to collect the shaft vibration acceleration. The net torque is generated through vibration compensation. The net torque is equal to the original torque signal minus the product of the shaft stiffness coefficient and the integral value of the shaft vibration acceleration.

[0018] Preferably, the specific analysis method of the four-dimensional situation factor includes:

[0019] The over-temperature hazard value is obtained by calculating the difference between the real-time winding temperature and the ambient temperature, and dividing it by the difference between the material's heat resistance limit temperature and the ambient temperature.

[0020] The fundamental and harmonic components are separated from the three-phase current. The percentage of the harmonic component amplitude to the fundamental component amplitude is calculated as the harmonic distortion rate. The percentage of the maximum deviation of the three-phase current amplitude to the average amplitude is calculated in real time as the current imbalance. The harmonic distortion rate and the current imbalance are linearly superimposed with a temperature-adaptive weighting coefficient to generate the current instability index. The current instability index is input into a preset nonlinear decay function, and the output is a current stability coefficient with a range between 0 and 1.

[0021] Subtract the percentage of the absolute value of the difference between the real-time voltage and the rated voltage relative to the rated voltage from 1, and then multiply by an exponential function that decays over time to obtain the voltage stability coefficient.

[0022] Calculate the percentage of the absolute value of the difference between the input frequency and the set frequency relative to the set frequency to obtain the frequency deviation value;

[0023] The over-temperature hazard value, current stability coefficient, voltage stability coefficient, and frequency deviation value are combined to form a four-dimensional situation factor.

[0024] Preferably, the fourth-order transmission network is configured with four independent transmission links for over-temperature hazard, current instability, voltage fluctuation, and frequency offset; each link contains three levels of nodes: the input node receives the situation factor components, the hidden node multiplies each component by the working condition adaptive weight and then accumulates them to generate a risk accumulation amount, and the output node outputs a high-level flag when the risk accumulation amount exceeds the link threshold; the output flags of the four links form a four-bit binary code.

[0025] Preferably, the generation of the primary warning signal includes:

[0026] When any two components of the four-dimensional situation factor exceed the first-level threshold at the same time, the first-level warning flag is triggered; when the over-temperature danger value is greater than 0.8 and the current stability coefficient is less than 0.3, the second-level warning flag is triggered; the binary flags of the four links are combined into a four-bit code and mapped to the preset warning level matrix.

[0027] Preferably, the triggering of the efficiency anomaly flag includes:

[0028] The percentage of output mechanical power divided by input electrical power is calculated, where output power is the product of torque and angular velocity, and input power is the square root of three times the product of voltage, current, and power factor. When the motor efficiency is lower than the dynamic threshold and the duration exceeds the preset delay, an efficiency abnormality flag is triggered.

[0029] The dynamic threshold is automatically adjusted based on the load rate: the threshold increases by 2% when the load rate is below 40%, and decreases by 3% when the load rate is above 80%.

[0030] Preferably, the reconstruction of the final warning instruction includes;

[0031] Establish priority rules: the second-level warning flag overrides the first-level flag, and the efficiency anomaly flag raises the warning level by one level; when the first-level warning flag and the efficiency anomaly flag coexist, the third-level warning command is output; when the second-level warning flag and the efficiency anomaly flag coexist, the emergency shutdown command is output.

[0032] Preferably, the hierarchical control includes:

[0033] Level 1 response: Adjust the inverter output frequency to the preset efficiency point; Level 2 response: Inject harmonic compensation current into the motor windings and start the forced cooling device; Level 3 response: Cut off the power supply circuit and trigger the mechanical braking system; Emergency stop response: When the command is emergency stop, immediately trigger the circuit breaker to trip and mechanical braking.

[0034] The technical effects and advantages of this invention are as follows:

[0035] 1. This invention uses adaptive deviation values ​​under variable frequency operating conditions to correct the voltage-frequency relationship in real time, effectively overcoming the false alarm defects of traditional fixed thresholds when the load changes suddenly. At the same time, the current stability coefficient integrates harmonic distortion, unbalance, and temperature effects, greatly improving the accuracy of transient disturbance identification and solving the smoothing distortion problem of traditional linear algorithms.

[0036] 2. This invention achieves early detection of complex faults by coupling the dynamic correlation of temperature, current, voltage, and frequency through four-dimensional situation factors; the fourth-order transfer network significantly shortens the early warning response delay through distributed risk accumulation calculation, avoiding the risk of missed detection by single parameter evaluation.

[0037] 3. This invention significantly reduces false triggering of transient processes by combining efficiency anomaly marking with dynamic load rate adjustment thresholds and a delayed triggering mechanism; finally, the early warning command reconstruction establishes cross-dimensional upgrade rules for energy efficiency anomalies and safety risks, significantly improving the ability to intercept early faults.

[0038] 4. This invention achieves continuous energy efficiency optimization by driving the frequency converter to track the optimal efficiency point through a first-level response; the second-level response effectively mitigates recoverable faults through harmonic suppression and active temperature control; and the third-level response's rapid protection mechanism significantly reduces the risk of major accidents. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0040] Figure 2 This is a schematic diagram of the dynamic early warning and energy efficiency integration process structure of the present invention;

[0041] Figure 3 This is a schematic diagram of the closed-loop control process structure of the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] like Figure 1-3 The situational awareness-based asynchronous motor energy-saving monitoring and dynamic early warning method shown includes the following steps:

[0044] S1: Multi-source heterogeneous data synchronous acquisition: Real-time acquisition of power supply parameter data and operating parameter data of the target asynchronous motor to obtain the adaptive deviation value and current stability coefficient of variable frequency operation;

[0045] The power supply parameter data of the target asynchronous motor includes the voltage and power supply frequency at the motor power supply input terminal, and the operating parameter data includes the torque, speed, motor winding temperature, and three-phase current at the motor mechanical output terminal.

[0046] It should be specifically noted that the power supply parameter data is collected on the power supply cable between the circuit breaker and the motor stator. This location allows direct acquisition of the voltage signal at the motor's power input terminal, facilitating accurate extraction of the zero-crossing distortion characteristics of the voltage waveform. The acquisition tool is a high-frequency voltage sensor with high response frequency and high measurement accuracy, used to couple the voltage signal and extract the zero-crossing distortion characteristics. The measurement range covers the motor's rated voltage, with a measurement accuracy ≥0.5 and a response frequency ≥10kHz. Simultaneously, a multi-channel data acquisition card with a sampling rate ≥10kHz is used, connected to the sensor output terminal, to convert the analog signal output by the sensor into a digital signal, which is then transmitted to the processor for further processing.

[0047] It should be noted that the adaptive deviation value of the variable frequency operating condition is extracted by coupling a high-frequency voltage sensor on the power supply cable between the circuit breaker and the motor stator to extract the zero-crossing distortion characteristics of the voltage waveform.

[0048] Record the time interval Δt between consecutive zero crossings of the voltage waveform. n The real-time operating frequency is calculated by the zero-crossing point of the voltage waveform. Where median(Δt) n This indicates that the median of the continuous zero-crossing time interval sequence is used to obtain the adaptive deviation value for variable frequency operation. Where f set The preset motor operating frequency for the system.

[0049] It should be noted that the system's preset motor operating frequency f setThe baseline value is the rated frequency marked on the nameplate of the target asynchronous motor. The rated frequency is the reference operating frequency during motor design, at which the electromagnetic and mechanical characteristics of the motor are in optimal matching state, and it is the core parameter to ensure motor efficiency and lifespan. In my country, industrial motors commonly use 50Hz, while some imported equipment uses 60Hz. For a motor with a rated frequency of 50Hz, if there are no special load requirements, f set The initial value should be set to 50Hz.

[0050] If the motor-driven load needs to operate at a non-rated frequency, f set It needs to be adjusted according to the optimal operating frequency of the load. For square torque loads such as fans and pumps, the load power is proportional to the cube of the speed. If it is necessary to reduce the flow rate or pressure, the operating frequency can be reduced by using a frequency converter. In this case, f set Set this as the target frequency. For constant torque loads such as conveyor belts and mixers: if it is necessary to maintain a constant torque while adjusting the speed, f set Set the frequency to meet the load speed requirements.

[0051] It should be specifically noted that the torque data acquisition location in the operating parameters is between the motor output shaft and the load coupling. A strain gauge torque flange is embedded at this location to directly acquire the raw torque signal output by the motor; simultaneously, a piezoelectric accelerometer is deployed on the same shaft segment as the torque flange to acquire shaft vibration acceleration and perform vibration compensation on the raw torque signal. The torque data acquisition tools are the strain gauge torque flange and the piezoelectric accelerometer. The measurement range of the strain gauge torque flange matches the rated torque of the motor, with a measurement accuracy of 0.1%FS, and its operating temperature range is adapted to the motor's operating environment; the piezoelectric accelerometer has high sensitivity ≥10mV / g and a wide frequency response of 10-1000Hz, ensuring accurate acquisition of shaft vibration acceleration. The data acquisition card synchronously acquires the signals from both sensors and transmits them to the processor.

[0052] The speed data acquisition location is set at the non-output shaft end of the selected motor to avoid affecting the normal operation of the motor output end. The acquisition tool is a photoelectric encoder with a resolution of ≥1000 pulses / revolution, which accurately measures the motor speed; the sensor converts the speed information into an electrical signal, which is transmitted to the processor through the data acquisition card.

[0053] The motor winding temperature data acquisition point is located inside the motor windings, allowing direct measurement of the winding's actual temperature. A similar sensor is also installed near the motor in a ventilated area to collect ambient temperature data. The acquisition tool is a platinum resistance temperature sensor, which has a measurement range of -50 to 200℃ and an accuracy of ±0.5℃, meeting the measurement requirements for both motor winding and ambient temperatures. The data acquisition card converts the analog signals output by the sensors into digital signals and transmits them to the processor.

[0054] The three-phase current data acquisition location is set inside the motor junction box, where a three-channel Rogowski coil is installed to synchronously and accurately acquire the instantaneous values ​​of the three-phase current at close range. The acquisition tool is a three-channel Rogowski coil, whose measurement range covers the rated current of the motor and has a bandwidth of ≥10kHz to ensure that high-frequency components in the current can be acquired. Combined with a data acquisition card with a sampling rate of ≥10kHz and a processor, independent sliding statistical analysis is performed on each phase current to calculate the current stability coefficient.

[0055] It should be noted that the torque is obtained by embedding a strain gauge torque flange between the motor output shaft and the load coupling to acquire the original torque signal. At the same time, a piezoelectric accelerometer is installed on the same shaft section as the torque flange to synchronously acquire the shaft vibration acceleration. The net torque T is generated through vibration compensation. net =T raw -K*∫a dt, where T raw is the original torque signal, a is the shaft vibration acceleration, and K is the shaft stiffness coefficient.

[0056] It is important to note that the shaft stiffness coefficient K is calculated by collecting the overall structural parameters of the shaft system, which consists of the motor output shaft, torque flange, and load coupling, including the material properties and geometric dimensions of each shaft segment. The shaft system typically comprises multiple shaft segments with different structures, such as the motor output shaft segment, torque flange segment, and coupling connection segment. The stiffness of each shaft segment is calculated using the torsional stiffness formula for circular shafts from mechanics of materials. Where d i Let L be the diameter of the i-th segment of the axis. i Let be the effective length of the i-th shaft segment, and E be the elastic modulus of the material. If the shaft system is a series structure, the theoretical value of the total stiffness K is the reciprocal of the sum of the reciprocals of the stiffnesses of each segment.

[0057] It should be noted that the current stability coefficient is obtained by installing a three-channel Rogowski coil in the motor junction box, synchronously collecting the instantaneous values ​​of the three-phase current, and performing independent sliding statistical analysis on the current of each phase.

[0058] Window length Where f is the power supply frequency, and the window length N is adaptively adjusted according to the fundamental period; phase current fluctuation dispersion Where k represents phase A, phase B, phase C in the three-phase current, and σ represents phase σ. k (I) represents the fluctuation dispersion of the k-th phase current, std(I) k ) represents the sequence of instantaneous current values ​​in the k-th phase, mean(I k The value of the k-th phase current sequence is represented by ); the current stability coefficient S(I) = 1 - max[σ] is obtained based on the window length and the phase current fluctuation dispersion. a (I), σ b (I), σ c(I)].

[0059] S2: Generate situation factors: Based on the multi-source heterogeneous data collected by S1, generate over-temperature hazard value, current stability coefficient, voltage stability coefficient and frequency deviation value, and construct a four-dimensional situation factor;

[0060] It should be specifically noted that the over-temperature hazard value is calculated using the real-time winding temperature T1, ambient temperature T2, and material heat resistance limit temperature T3 obtained from data collection.

[0061] The current stability coefficient separates the fundamental component I of the three-phase current using Fourier transform. 基波 Harmonic component I 谐波 Calculate the harmonic distortion rate Calculate current unbalance Where ΔI max I represents the maximum deviation between the amplitude and average value of the three-phase current. avg The average amplitude of the three-phase current; the current instability index I is obtained based on the harmonic distortion rate and the current imbalance. 失稳 =α*THD+β*I u Where α and β are temperature-adaptive weights, α is 0.6 and β is 0.4 when the winding temperature T1 > 100℃; otherwise, α is 0.4 and β is 0.6. The current stability coefficient is calculated based on this instability index. Where k is a constant calibrated experimentally, the core function of k is to determine when I 失稳 When S is the critical maximum value for normal operation of the motor, I It should be close to 0; when I 失稳 When S is the ideal steady-state value of the motor, I It should be close to 1.

[0062] The voltage stability factor is calculated as the percentage of the absolute value of the difference between the real-time voltage and the rated voltage relative to the rated voltage. Obtain the voltage stability coefficient Where t is the duration of voltage deviation and τ is the attenuation constant, which is set according to the stability of the power grid. If the power grid in the area is relatively stable, the voltage fluctuation is relatively small and the amplitude is small, and τ is 60s. For some high-precision motors with extremely high requirements for voltage stability, τ is 10s.

[0063] It should be noted that as the duration t of the voltage deviation increases, the exponential term decays, leading to a decrease in the voltage stability coefficient. This aligns with the physical law that long-term voltage anomalies exacerbate the cumulative damage to motor insulation. The exponential decay is chosen over the nonlinear decay because the severity of voltage deviation increases nonlinearly over time.

[0064] The frequency deviation value F is obtained by calculating the percentage of the absolute value of the difference between the input frequency and the set frequency relative to the set frequency.

[0065] Combining the above-mentioned over-temperature hazard value, current stability coefficient, voltage stability coefficient, and frequency deviation value, we get a four-dimensional situation factor [H, S]. I S U F].

[0066] S3: Network dynamic early warning transmission: Construct a fourth-order transmission network corresponding to the four-dimensional situation factors, output path markers, and generate primary early warning signals based on the combination of fourth-order path markers;

[0067] It should be specifically noted that the fourth-order transmission network uses an industrial-grade processor to run the network model, ensuring real-time performance; a programmable logic controller (PLC) is used to implement node logic judgments. The first-order link corresponds to the over-temperature hazard value and is responsible for transmitting temperature risk; the second-order link corresponds to the current stability coefficient and is responsible for transmitting current instability risk; the third-order link corresponds to the voltage stability coefficient and is responsible for transmitting voltage fluctuation risk; and the fourth-order link corresponds to the frequency deviation value and is responsible for transmitting frequency offset risk. Each link includes an input node, a hidden node, and an output node.

[0068] The input nodes receive over-temperature hazard values, current stability coefficients, voltage stability coefficients, and frequency deviation values, respectively; the hidden nodes introduce adaptive operating condition weights to calculate the cumulative risk R = w1*H + w2*S. I +w3*S U +w4*F, where w1, w2, w3, and w4 are the corresponding situation factor weights, and w1+w2+w3+w4=1; the output node sets the link thresholds: over-temperature danger threshold 0.6, current instability threshold 0.4, voltage fluctuation threshold 0.6, and frequency offset threshold 5%. When R exceeds the threshold, it outputs 1 (high level); otherwise, it outputs 0 (low level).

[0069] It should be noted that the corresponding situation factor weights are dynamically adjusted based on the real-time motor load rate. According to the characteristics of the load rate's impact on motor operating risk, the load rate is divided into three ranges: low load <40%, medium load 40%-80%, and high load >80%, with weights assigned to each range.

[0070] Voltage fluctuations under low load have a significant impact on efficiency, and voltage instability is easily caused by light load. The values ​​of w1, w2, w3, and w4 are 0.2, 0.2, 0.4, and 0.2, respectively. The voltage stability weight w3 is increased to 0.4 because voltage fluctuations under low load can easily lead to increased iron loss in the motor and a significant decrease in energy efficiency.

[0071] Under medium load, the impact of various risk factors is balanced and needs to be comprehensively evaluated. The values ​​of w1, w2, w3, and w4 are 0.25, 0.25, 0.25, and 0.25, respectively, with equal weights for the four factors. Since medium load is the optimal range for motor design, the risk contributions of over-temperature, current instability, voltage fluctuation, and frequency deviation are similar.

[0072] Under high load, the risk of overheating and current instability is prominent, and the motor is prone to overheating due to overload. The values ​​of w1, w2, w3, and w4 are 0.4, 0.3, 0.15, and 0.15, respectively. The overheating risk weight w1 is increased to 0.4, and the current stability weight w2 is increased to 0.3. Under high load, the winding heating is aggravated and the current fluctuation is increased, which is a common cause of motor failure.

[0073] The load rate is calculated in real time by the ratio of the motor's real-time output power to its rated output power. When the load rate switches from one range to another, the weight immediately switches according to the corresponding range value. To avoid fluctuations caused by frequent switching, a hysteresis range is set. When the load rate is between 38% and 42%, the medium load weight is maintained. If the motor is in the starting stage, the current stability weight w2 is temporarily increased to 0.4 because the current surge is large during startup. If frequent fluctuations in the power grid frequency F>5% are detected for more than 10 seconds, the frequency deviation weight w4 is increased to 0.3.

[0074] It should be specifically noted that the primary warning signal is generated by encoding four-bit binary codes from the output tags of four links, mapping them to a preset warning level matrix, and includes:

[0075] When any two components of the four-dimensional situation factor exceed the first-level threshold at the same time, the first-level warning flag is triggered; when the over-temperature danger value is greater than 0.8 and the current stability coefficient is less than 0.3, the second-level warning flag is triggered; the binary flags of the four links are combined into a four-bit code and mapped to the preset warning level matrix.

[0076] It should be noted that the first-level threshold for overheating is set at 0.6. This value corresponds to a temperature difference between the motor windings and the ambient temperature reaching 60% of the material's heat resistance limit, at which point the motor faces a certain risk of overheating. The first-level threshold for the current stability coefficient is set at 0.5, with a range of 0-1. A smaller value indicates a more unstable current. I A value <0.5 indicates that the current fluctuation or distortion has exceeded the normal range; the first-level threshold for the voltage stability coefficient is set to 0.7. The closer the voltage stability coefficient is to 1, the more stable the voltage. U A value less than 0.7 indicates that voltage deviation or fluctuation has significantly affected motor operation; the first-level threshold for frequency deviation is set at 3%. That is, when the absolute value of the deviation between the input frequency and the set frequency exceeds 3% of the set frequency, it may affect motor efficiency and operational stability.

[0077] S4: Energy efficiency fusion correction: Real-time calculation of motor efficiency. When the motor efficiency is less than the preset efficiency threshold, an efficiency anomaly flag is triggered. The efficiency anomaly flag and the primary warning signal are merged and reconstructed into the final warning command.

[0078] It should be noted that the motor efficiency is obtained by the ratio of output mechanical power to input electrical power. The preset efficiency threshold is set according to the rated efficiency on the motor nameplate and is corrected by the load rate. When the load rate is <40%, the preset efficiency threshold is 2% higher than the baseline value. When the load rate is >80%, the preset efficiency threshold is 3% lower than the baseline value. When the motor efficiency is <efficiency threshold and the duration exceeds 30 seconds, an efficiency abnormality flag is triggered.

[0079] It should be specifically noted that the reconstruction of the final warning instruction follows these rules:

[0080] If the primary warning signal is no warning: if there is an efficiency anomaly marker, a first-level warning instruction is generated directly;

[0081] If the initial warning signal is a Level 1 warning: if there is an efficiency anomaly marker, it will be upgraded to a Level 2 warning instruction;

[0082] If the primary warning signal is a Level 2 warning: when an efficiency anomaly marker exists, an emergency shutdown command is generated directly;

[0083] If the primary warning signal already contains a marker associated with efficiency anomalies, it will not be upgraded again, and the highest level will be used.

[0084] The priority rule is as follows: the second-level warning flag covers the first-level warning; the efficiency anomaly flag raises the warning level by one level; the second-level warning plus the efficiency anomaly flag triggers an emergency shutdown command.

[0085] S5: Closed-loop control response: Execute hierarchical control according to the final warning command.

[0086] It should be specifically noted that the hierarchical control includes:

[0087] Level 1 response: When the command is a Level 1 warning, the output frequency is adjusted to the preset efficiency point through the frequency converter;

[0088] Level 2 response: When the command is a Level 2 warning, the harmonic compensation device is activated to inject harmonic compensation current into the motor windings, and the forced cooling device is activated at the same time to reduce the winding temperature.

[0089] Level 3 response: When the instruction is a Level 3 warning, the power supply circuit is cut off by the circuit breaker, and the mechanical braking system is triggered at the same time, with a braking time of ≤0.5s;

[0090] Emergency stop response: When the instruction is an emergency stop, the circuit breaker is immediately tripped and the mechanical brake is applied, and an alarm is issued through an audible and visual alarm with a volume of ≥85dB.

[0091] After control is executed, the motor temperature, current and efficiency are collected in real time. If the parameters return to the normal range, the warning is lifted; if the parameters continue to be abnormal, the control level is upgraded.

[0092] Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0093] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness, characterized in that, include: S1: Multi-source heterogeneous data synchronous acquisition: Real-time acquisition of power supply parameter data and operating parameter data of the target asynchronous motor to obtain the adaptive deviation value and current stability coefficient of variable frequency operation; The power supply parameter data of the target asynchronous motor includes the voltage and power supply frequency at the motor power supply input terminal, and the operating parameter data includes the torque, speed, motor winding temperature, and three-phase current at the motor mechanical output terminal. S2: Generate situation factors: Based on the multi-source heterogeneous data collected by S1, generate over-temperature hazard value, current stability coefficient, voltage stability coefficient and frequency deviation value, and construct a four-dimensional situation factor; S3: Network dynamic early warning transmission: Construct a fourth-order transmission network corresponding to the four-dimensional situation factors, output path markers, and generate primary early warning signals based on the combination of fourth-order path markers; S4: Energy efficiency fusion correction: Real-time calculation of motor efficiency. When the motor efficiency is less than the preset efficiency threshold, an efficiency anomaly flag is triggered. The efficiency anomaly flag and the primary warning signal are merged and reconstructed into the final warning command. S5: Closed-loop control response: Execute hierarchical control according to the final warning command.

2. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The adaptive deviation value for variable frequency operation is obtained by coupling a high-frequency voltage sensor on the power supply cable between the circuit breaker and the motor stator to extract the zero-crossing distortion characteristics of the voltage waveform. Record the time intervals between consecutive zero crossings of the voltage waveform, take the median of these time interval sequences, multiply the median by two and take the reciprocal to obtain the real-time operating frequency; the adaptive deviation value of this variable frequency operating condition is equal to the absolute value of the difference between the actual operating frequency and the system preset motor operating frequency, divided by the larger of the system preset frequency and 10Hz, and then multiplied by 100% to express the percentage deviation.

3. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The current stability coefficient is obtained by installing a three-channel Rogowski coil in the motor junction box, synchronously collecting the instantaneous values ​​of the three-phase current, and performing independent sliding statistical analysis on the current of each phase. The window length is calculated based on the power supply frequency: divide the power supply frequency by 50, round the result to the nearest integer, and then multiply by 10. The window length is adaptively adjusted according to the fundamental frequency period. The fluctuation dispersion of each phase current is equal to the standard deviation of the instantaneous value sequence of the phase current divided by the average value of the phase current sequence. The fluctuation dispersion of phases A, B, and C are calculated separately. The current stability coefficient is obtained by subtracting the maximum value of the three-phase current fluctuation dispersion from 1.

4. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The torque is obtained by embedding a strain gauge torque flange between the motor output shaft and the load coupling to collect the original torque signal. At the same time, a piezoelectric acceleration sensor is installed on the same shaft section of the torque flange to synchronously collect the shaft vibration acceleration. The net torque is generated through vibration compensation. The net torque is equal to the original torque signal minus the product of the shaft stiffness coefficient and the integral value of the shaft vibration acceleration.

5. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The specific analysis methods for the four-dimensional situation factors include: The over-temperature hazard value is obtained by calculating the difference between the real-time winding temperature and the ambient temperature, and dividing it by the difference between the material's heat resistance limit temperature and the ambient temperature. The fundamental and harmonic components are separated from the three-phase current. The percentage of the harmonic component amplitude to the fundamental component amplitude is calculated as the harmonic distortion rate. The percentage of the maximum deviation of the three-phase current amplitude to the average amplitude is calculated in real time as the current imbalance. The harmonic distortion rate and the current imbalance are linearly superimposed with a temperature-adaptive weighting coefficient to generate the current instability index. The current instability index is input into a preset nonlinear decay function, and the output is a current stability coefficient with a range between 0 and 1. Subtract the percentage of the absolute value of the difference between the real-time voltage and the rated voltage relative to the rated voltage from 1, and then multiply by an exponential function that decays over time to obtain the voltage stability coefficient. Calculate the percentage of the absolute value of the difference between the input frequency and the set frequency relative to the set frequency to obtain the frequency deviation value; The over-temperature hazard value, current stability coefficient, voltage stability coefficient, and frequency deviation value are combined to form a four-dimensional situation factor.

6. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The fourth-order transmission network is configured with four independent transmission links for over-temperature hazard, current instability, voltage fluctuation, and frequency offset. Each link contains three levels of nodes: the input node receives the situation factor components, the hidden node multiplies each component by the working condition adaptive weight and then accumulates them to generate the risk accumulation amount, and the output node outputs a high-level flag when the risk accumulation amount exceeds the link threshold. The output flags of the four links form a four-bit binary code.

7. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The generation of the primary warning signal includes: When any two components of the four-dimensional situation factor exceed the first-level threshold at the same time, the first-level warning flag is triggered; when the over-temperature danger value is greater than 0.8 and the current stability coefficient is less than 0.3, the second-level warning flag is triggered; the binary flags of the four links are combined into a four-bit code and mapped to the preset warning level matrix.

8. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The triggering of the efficiency anomaly flag includes: The percentage of output mechanical power divided by input electrical power is calculated, where output power is the product of torque and angular velocity, and input power is the square root of three times the product of voltage, current, and power factor. When the motor efficiency is lower than the dynamic threshold and the duration exceeds the preset delay, an efficiency abnormality flag is triggered. The dynamic threshold is automatically adjusted based on the load rate: the threshold increases by 2% when the load rate is below 40%, and decreases by 3% when the load rate is above 80%.

9. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness according to claim 1, characterized in that: The reconstruction of the final warning instruction includes; Establish priority rules: Level 2 warning flags cover Level 1 warnings, and abnormal efficiency flags raise the warning level by one level; When the first-level warning flag and the efficiency anomaly flag coexist, the third-level warning command is output; When the Level 2 warning flag and the efficiency anomaly flag coexist, an emergency shutdown command is output.

10. The method for energy-saving monitoring and dynamic early warning of asynchronous motors based on situational awareness as described in claim 1, characterized in that: The hierarchical control includes: Level 1 response: Adjust the inverter output frequency to the preset efficiency point; Level 2 response: Inject harmonic compensation current into the motor windings and start the forced cooling device; Level 3 response: Cut off the power supply circuit and trigger the mechanical braking system; Emergency stop response: When the command is emergency stop, immediately trigger the circuit breaker to trip and mechanical braking.

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