LNG intelligent impeller supercharging pump regulation control method and system

Abstract

The application relates to the technical field of liquefied natural gas filling equipment control, and particularly discloses an intelligent impeller booster pump regulating control method and system of LNG, which discards a flow sensor, obtains active and reactive power of a motor from a frequency converter, calculates a power factor, a standard deviation and an active power response steepness to determine a high-efficiency preselected area; vibration signals of a pump body are collected, FFT transformation is carried out, sub-leaf frequency band energy is extracted, a normalized cavitation erosion index is calculated, a dynamic safety boundary is determined, a guide vane is normally locked, and only a frequency converter rotating speed is regulated to stabilize an outlet pressure; when efficiency deviates and a safety margin is sufficient, one-way fixed-step guide vane exploration is triggered; and when an upper limit is exceeded, a 2-time-step reverse rollback is executed, and a 24-hour exploration-prohibition area is set. The application does not need a flowmeter, and the frequency of guide vane action is extremely low, so that the pump can be long-term operated in a high-efficiency area near a cavitation safety boundary, operation efficiency, cavitation protection and equipment service life are considered, and the application is suitable for wide-fluctuation working conditions of LNG vehicle filling stations.

Description

Technical Field

[0001] This invention relates to the field of liquefied natural gas (LNG) refueling equipment control technology, and in particular to a method and system for regulating and controlling an intelligent LNG impeller booster pump. Background Technology

[0002] The booster pump at LNG vehicle refueling stations needs to pressurize the low-pressure LNG in the storage tank to the rated high pressure of the refueling machine. The random arrival of refueling vehicles causes the pump's operating point to fluctuate significantly between zero-flow pressure maintenance and full-load fast charging conditions. The industry generally adopts a dual-degree-of-freedom pump structure with variable frequency motor and adjustable guide vanes. The speed is adjusted by the frequency converter to stabilize the outlet pressure, and the flow signal is collected by the cryogenic flow meter. The guide vane position is adjusted in combination with the preset efficiency contour line to maintain efficient operation.

[0003] However, existing control methods have some technical problems in actual long-term operation. The high-precision flowmeters that are adapted to low temperatures of -162℃ and are resistant to two-phase flow interference are expensive to manufacture and maintain. The signals are prone to drift in low-temperature environments and are prone to failure in drainage and defrosting conditions. Flow measurement failure will directly lead to inaccurate efficiency calculations and the guide vane adjustment loop will not converge, which will increase the energy consumption of the equipment. In addition, in order to prevent cavitation damage, the existing technology requires setting a fixed lower limit of the guide vane opening based on the worst operating conditions. This boundary is too conservative and cannot adapt to the real-time operating conditions of the pump, which limits the utilization of the high-efficiency range. If the boundary is relaxed, the guide vane needs to be frequently tested with small amplitudes. The low temperature of LNG will harden the sealing material of the guide vane actuator. High-frequency small-amplitude reciprocating motion will cause irreversible fretting wear failure, causing the pump to degrade to fixed guide vane mode operation in a short period of time. It is impossible to balance operating efficiency, cavitation safety and actuator service life.

[0004] Therefore, there is an urgent need for LNG intelligent impeller booster pump regulation and control methods and systems to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for regulating and controlling an intelligent impeller booster pump for LNG, comprising the following steps: The motor electrical parameters output by the frequency converter driving the booster pump are obtained, the time-domain features of the motor electrical parameters are extracted, and an efficiency trend criterion is generated. When the efficiency trend criterion meets the preset high-efficiency zone conditions, the booster pump is determined to be in the high-efficiency pre-selection zone. The vibration signal of the booster pump is collected, and the vibration signal is processed in the frequency domain to extract the ratio of the energy component of the preset characteristic frequency band to the energy component of the full frequency band, which is used as the cavitation safety criterion. Without triggering guide vane exploration, the adjustable guide vane is locked at the current angle, and the motor speed is adjusted by the frequency converter according to the deviation between the pump outlet pressure and the target outlet pressure. The efficiency trend criterion and the cavitation safety criterion are continuously monitored. When both meet the preset exploration triggering conditions within a preset time period, the adjustable guide vane is controlled to perform a preset step size reduction adjustment. After the opening reduction adjustment is completed, the cavitation safety criterion is reacquired. If the reacquired cavitation safety criterion does not exceed the preset safety limit, the adjusted guide vane angle is locked and the state of non-triggered guide vane exploration is returned. If the safety limit is exceeded, the adjustable guide vane is controlled to perform an opening increase adjustment with a preset backtracking step, and the backtracked position is marked as a prohibited exploration area within a preset time period.

[0006] Furthermore, the present invention also discloses an LNG intelligent impeller booster pump regulation and control system, comprising: The acquisition module is used to acquire the motor electrical parameters output by the frequency converter driving the booster pump, extract time-domain features from the motor electrical parameters, generate efficiency trend criteria, and determine that the booster pump is in the high-efficiency pre-selection zone when the efficiency trend criteria meet the preset high-efficiency zone conditions. The acquisition module is used to acquire the vibration signal of the booster pump, perform frequency domain processing on the vibration signal, and extract the ratio of the energy component of the preset characteristic frequency band to the energy component of the full frequency band as a cavitation safety criterion. The control module is used to lock the adjustable guide vane at the current angle when the guide vane exploration is not triggered, and adjust the speed of the motor according to the deviation between the pump outlet pressure and the target outlet pressure through the frequency converter. The monitoring module is used to continuously monitor the efficiency trend criterion and the cavitation safety criterion. When both meet the preset exploration triggering conditions simultaneously within a preset time period, the module controls the adjustable guide vane to perform a preset step size reduction adjustment. The correction module is used to reacquire the cavitation safety criterion after the opening reduction adjustment is completed. If the reacquired cavitation safety criterion does not exceed the preset safety limit, the adjusted guide vane angle is locked and the state of no guide vane exploration is returned. If the safety limit is exceeded, the adjustable guide vane is controlled to perform an opening increase adjustment with a preset backtracking step, and the backtracked position is marked as a prohibited exploration area within a preset time period.

[0007] Furthermore, the control module includes: The definition unit is used to define the silent cruise state, in which the set angle of the adjustable guide vane is maintained at the angle value stored after the most recent successful exploration, and the guide vane angle update command is prohibited. The acquisition unit is used to acquire the real-time outlet pressure signal fed back by the pressure transmitter on the pump outlet pipeline, and calculate the pressure deviation based on the real-time outlet pressure signal and the preset target outlet pressure. The instruction generation unit is used to take the pressure deviation as input, execute the feedback control algorithm, generate a speed adjustment instruction, and execute it through the frequency converter, so as to keep the angle of the adjustable guide vane unchanged during the motor speed adjustment process.

[0008] This application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described LNG intelligent impeller booster pump regulation and control method.

[0009] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described LNG intelligent impeller booster pump regulation and control method.

[0010] The beneficial effects of this application are as follows: Firstly, this invention eliminates the need for a flow sensor and directly reuses the active and reactive power parameters of the inverter's inherent output to extract the high-efficiency zone determination characteristics. This eliminates the defects of low-temperature flow meters, such as high cost, signal drift, and malfunction, from the source, reducing equipment investment and maintenance costs, and improving the stability and reliability of the control logic.

[0011] Secondly, this invention quantifies the cavitation erosion intensity by using the sub-vane frequency vibration signal of the pump body, and constructs a dynamic adaptive cavitation safety boundary to replace the traditional fixed conservative guide vane lower limit. Under the premise of ensuring cavitation safety, it fully releases the pump's high-efficiency operating range to improve the overall operating efficiency of the booster pump.

[0012] Third, the present invention adopts a control logic of silent cruise of the guide vane under normal conditions and single-step large stepping in two conditions, which reduces the number of actions of the guide vane actuator to an extremely low level, eliminates the problem of micro-motion wear failure of the guide vane actuator under LNG cryogenic conditions, and greatly extends the service life of the equipment. At the same time, the outlet pressure is quickly adjusted independently by the motor speed, taking into account the stability of the refueling pressure, operating efficiency and equipment reliability. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a method flow proposed in an embodiment of this application.

[0014] Figure 2 This is a schematic diagram of the system structure proposed in an embodiment of the present invention.

[0015] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0016] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0017] likeFigure 1 As shown, this application provides a method for regulating and controlling an LNG intelligent impeller booster pump, including the following steps: Step S1: Obtain the real-time active power and reactive power of the motor from the frequency converter driving the booster pump. Calculate the real-time power factor by dividing the active power by the square root of the sum of the squares of the active power and the reactive power. Within a sliding window of a preset time length, calculate the standard deviation of all power factor values ​​as the power factor fluctuation. Simultaneously, continuously calculate the derivative of the active power with respect to time within the window, and record the maximum value of the derivative that appears in the window as the active power response steepness. When all three conditions are met simultaneously—real-time power factor greater than a preset power factor threshold, power factor fluctuation less than a preset fluctuation threshold, and active power response steepness greater than a preset response steepness threshold—it is determined that the booster pump is currently operating in the high-efficiency pre-selection zone; otherwise, it is determined that it has deviated from the high-efficiency pre-selection zone. Step S2: Collect the vibration acceleration signal installed at the non-drive end bearing housing of the booster pump, perform a fast Fourier transform on the signal to obtain the vibration spectrum, extract the vibration energy in the frequency band of 0.4 to 0.6 times the impeller passing frequency from the vibration spectrum. The impeller passing frequency is calculated as the product of the number of impeller blades and the number of revolutions per second at the pump's highest operating speed. At the same time, extract the total vibration energy of the same vibration spectrum in the entire frequency band from 10Hz to 2000Hz. Divide the vibration energy in the aforementioned frequency band by the total vibration energy in the entire frequency band to obtain the normalized cavitation erosion index. Compare the normalized cavitation erosion index with the micro-erosion allowable upper limit calibrated by the pre-shipment test and written into the controller. Step S3: Without triggering guide vane exploration, the angle of the adjustable guide vane is locked at the stored locking angle value. The speed of the motor is adjusted by the frequency converter based on the deviation between the real-time pressure signal fed back by the pump outlet pressure transmitter and the target outlet pressure, so as to maintain the stability of the outlet pressure. During this process, the adjustable guide vane does not produce any displacement. Step S4: Continuously monitor the latest power factor fluctuation obtained in step S1 and the latest normalized cavitation erosion index obtained in step S2. When the power factor fluctuation exceeds the first threshold and the normalized cavitation erosion index is lower than the second threshold within a first preset time period, trigger a guide vane exploration: perform a one-way guide vane angle step with a preset fixed amplitude in the direction of reducing the adjustable guide vane opening. After the step is completed, immediately lock the adjustable guide vane back to the new angle. Step S5: After the unidirectional guide vane angle stepping is completed and a second preset time of stabilization is achieved, the current normalized cavitation erosion index is obtained again through the process described in step S2. If the normalized cavitation erosion index after stepping still does not exceed the upper limit of micro-erosion allowable value, the adjusted adjustable guide vane angle is used as the new locked angle value, and the process returns to step S3. If the normalized cavitation erosion index after stepping has exceeded the upper limit of micro-erosion allowable value, a reverse adjustable guide vane stepping with an amplitude of 2 times the preset fixed amplitude is immediately executed, and the position locked in the reverse direction is marked as a no-exploration zone for the subsequent third preset time. During the no-exploration period, no new guide vane exploration is initiated in this direction.

[0018] As described in steps S1-S5 above, the operating point of the booster pump at the LNG vehicle refueling station fluctuates frequently and drastically between zero-flow pressure maintenance and full-load fast charging. Random changes in downstream load require the control system to quickly stabilize the outlet pressure. At the same time, the low-temperature environment of LNG causes the sealing material of the guide vane actuator to harden, and high-frequency small-amplitude reciprocating motion can cause fretting wear failure. In addition, high-precision low-temperature flow meters have problems such as high cost, signal drift, and easy failure. Traditional fixed cavitation safety boundaries are too conservative and cannot balance operating efficiency and equipment life. Therefore, a control method with no flow dependence, low guide vane motion, and dynamic cavitation constraints is needed to solve the three core contradictions of efficiency optimization, cavitation protection, and actuator life.

[0019] Existing control technologies rely on cryogenic flow meters to obtain flow signals for efficiency optimization. However, these flow meters are prone to failure under the cryogenic, two-phase flow conditions of LNG, leading to control disruptions. Furthermore, using fixed guide vane lower limits to avoid cavitation results in a conservative safety margin that wastes the high-efficiency zone. Additionally, high-frequency perturbation testing for optimization exacerbates wear on the guide vane actuator. This invention completely eliminates flow sensors, reusing the inherent electrical parameters of the frequency converter to determine the high-efficiency zone. It quantifies the cavitation intensity in real time through sub-vane frequency vibration of the pump body, normally locking the guide vane and using only speed to stabilize pressure. A single, large-step exploration is triggered only when efficiency deviates but safety is sufficient. If the limit is exceeded, a significant regression is implemented and a long-term exploration restriction is set. Therefore, it is necessary to address the shortcomings of existing technologies across the entire chain of sensing, control, and execution.

[0020] This invention constructs a full-process adjustment and control logic for an LNG intelligent impeller booster pump that eliminates flow sensor requirements, minimizes guide vane operation frequency, and features cavitation safety self-adaptation. Through closed-loop control including electrical parameter high-efficiency zone determination, vibration cavitation monitoring, normal guide vane locking, dual-condition triggering unidirectional exploration, and over-limit safety retreat and exploration prohibition, the booster pump can operate stably in the high-efficiency range near the cavitation safety boundary for a long period without the need for flow measurement.

[0021] This invention employs a control logic that prioritizes silent cruise and supplements it with trigger-based exploration. After power-on, the system enters a normal silent cruise state with the adjustable guide vanes mechanically locked. The outlet pressure is maintained by adjusting the motor speed solely through the frequency converter. The controller calculates the power factor fluctuation and active power response steepness in parallel and in real time to determine whether the booster pump deviates from the high-efficiency pre-selection zone. Simultaneously, it collects pump vibration signals to calculate the normalized cavitation erosion index and monitors the cavitation safety status in real time. When the booster pump continuously deviates from the high-efficiency zone and the cavitation safety margin is sufficient, it triggers a one-way fixed-step exploration with a reduced guide vane opening. After the step is completed, it waits in a steady state and re-verifies the cavitation index. If it is safe, the new guide vane position is locked; if it exceeds the limit, it immediately performs a reverse retreat with a step size of 2 and sets that position as a 24-hour no-exploration zone. The entire control process is conducted without the participation of a flow sensor. The guide vanes only perform a very few one-way large-step movements, causing the pump operating point to unidirectionally approach the high-efficiency zone along the cavitation safety boundary, achieving long-term stable flow-free adaptive optimization operation.

[0022] In one embodiment, step S1 specifically includes: S11: Read the current real-time active power and reactive power values ​​of the motor from the communication interface of the frequency converter at a fixed sampling period. The real-time active power and reactive power values ​​are physical quantities that the frequency converter must calculate online to realize the motor vector control or direct torque control. Based on the read real-time active power and reactive power values, calculate the real-time power factor by dividing the real-time active power value by the apparent power. The apparent power value is the square root of the sum of the square of the real-time active power value and the square of the real-time reactive power value.

[0023] In step S11 above, the real-time active power and reactive power values ​​of the motor are read from the inverter communication interface at a fixed sampling period. These two values ​​are essential online calculation quantities for the inverter to implement motor vector control or direct torque control, and no additional sensing equipment is required. Apparent power is calculated based on the real-time active power and real-time reactive power of the motor. The real-time power factor is then obtained by dividing the real-time active power value by the apparent power. The formula for calculating the real-time power factor is as follows: ; Among them, the Indicates the real-time power factor. This indicates the real-time active power of the motor. This indicates the real-time reactive power of the motor. The above steps can directly reuse existing hardware data without increasing hardware costs, providing basic electrical parameter support for determining the high-efficiency zone.

[0024] S12: Construct a sliding window with a length of 10 seconds. Within the sliding window, store continuous real-time power factor values ​​and active power sample values ​​in chronological order. Each time a new sampling moment is entered, the window slides forward by one sampling cycle and removes the earliest data point that entered the window. Step S12 above constructs a sliding window with a length of 10 seconds. Within the window, continuous real-time power factor values ​​and active power sample values ​​are stored in chronological order. Each time a new sampling time is entered, the window slides forward one sampling cycle and discards the earliest window data. The 10-second window length can stably capture the fluctuation patterns of electrical parameters, avoid interference from instantaneous operating condition disturbances on the characteristic calculation results, and ensure the stability of characteristic parameters.

[0025] S13: Within each sliding window, calculate the average value of all real-time power factor values ​​within the window, and then calculate the sum of squares of the differences between each real-time power factor value and the average value. Divide the sum of squares by the number of data points in the window minus 1 and take the square root to obtain the standard deviation of the power factor. The standard deviation of the power factor characterizes the fluctuation range of the power factor within the window period. At the same time, use the difference between two adjacent active power sample values ​​within the window divided by the sampling period to obtain the active power time derivative of each sampling interval, and record the maximum value of the active power time derivative that has appeared in the window. This maximum value reflects the active power response steepness. The specific formula for calculating the standard deviation of the power factor in step S13 above is as follows: ; Among them, the Indicates the standard deviation of the power factor. This represents the total number of sampling points within the sliding window (i.e., the number of sampling points within a 10-second sliding window). This represents the i-th power factor sample value within the sliding window. This represents the average power factor within the sliding window, characterizing the fluctuation range of the power factor. Simultaneously, the active power derivative with respect to time for each sampling interval is calculated by dividing the difference between adjacent active power samples by the sampling period. The maximum value of the derivative within the window is recorded as the active power response steepness, reflecting the pump's response speed to load changes. Under near-saturated LNG operating conditions, the power factor fluctuation is lower and the active power response is steeper during high-efficiency operation. This calculation method can accurately extract the unique characteristics of the high-efficiency zone without calculating specific efficiency values, reducing the controller's computing power requirements.

[0026] S14: The real-time power factor, power factor standard deviation, and active power response steepness obtained in real time are compared with the preset power factor threshold, preset fluctuation threshold, and preset response steepness threshold written into the controller during factory testing, respectively. Only when the real-time power factor is greater than the preset power factor threshold, the power factor standard deviation is less than the preset fluctuation threshold, and the active power response steepness is greater than the preset response steepness threshold, is it determined that the current operating point of the booster pump is in the high-efficiency pre-selection zone. Otherwise, it is considered that the booster pump has deviated from the high-efficiency pre-selection zone. This determination result is used for the guide vane exploration trigger logic decision in step S4.

[0027] Step S14 compares the real-time power factor, power factor standard deviation, and active power response steepness with preset power factor thresholds, preset fluctuation thresholds, and preset response steepness thresholds, respectively. The pump is determined to be in the high-efficiency pre-selection zone only if all three conditions are met simultaneously; otherwise, it is determined to have deviated from the high-efficiency pre-selection zone. This determination result is directly used by the guide vane exploration trigger logic. This qualitative determination method does not require flow data support, completely avoiding control anomalies caused by flow meter failure. It provides accurate efficiency deviation basis for subsequent low-frequency guide vane adjustments, aligning with the core design goal of reducing the number of guide vane actuator actions and extending actuator lifespan.

[0028] As described in steps S11-S14 above, the operating point of the booster pump in an LNG vehicle refueling station frequently changes between zero-flow pressure maintenance and full-load fast charging. Existing control methods rely on cryogenic flow meters to obtain flow signals in order to locate the high-efficiency zone. The cryogenic, two-phase flow conditions of LNG cause flow meter signal drift and measurement failure. After the flow data becomes invalid, both efficiency calculations and guide vane adjustments will deviate. Therefore, it is necessary to eliminate the need for flow sensors and instead directly extract the high-efficiency zone determination characteristics based on the inherent electrical parameters of the motor, thus solving the efficiency control failure problem caused by unreliable flow measurement.

[0029] Existing technologies determine the high-efficiency zone by directly measuring flow rate and calculating efficiency using flow meters. However, in cryogenic, two-phase flow scenarios like LNG, flow meters are prone to failure and are costly, failing to provide consistently reliable data over the long term. This paper proposes a sensorless high-efficiency zone determination method by utilizing the inherent calculation data from inverter vector control or direct torque control, and extracting the time-domain characteristics of power factor and active power through a sliding window algorithm. This method avoids the cost and reliability drawbacks of flow meters from the outset. By reusing the inherent output electrical parameters of the inverter and combining them with the sliding window algorithm to calculate the standard deviation of the power factor and the steepness of the active power response, a qualitative determination of the high-efficiency pre-selection zone of the booster pump without flow sensor involvement is achieved, providing a stable basis for judging efficiency trends in the guide vane exploration trigger logic.

[0030] In one embodiment, step S2 specifically includes: S21: A temperature-compensated piezoelectric vibration acceleration sensor is installed at the bearing housing position of the non-drive end of the booster pump. The charge signal output by the sensor is converted into a voltage signal by a charge amplifier, and then high-frequency noise is removed by an anti-aliasing low-pass filter. The signal is then converted from analog to digital by the analog high-speed acquisition channel of the programmable logic controller to obtain a discrete digital vibration sequence. The sampling frequency of the analog high-speed acquisition channel is set to be no less than 8 times the highest impeller passing frequency. The highest impeller passing frequency is the product of the number of impeller blades and the highest operating speed of the pump divided by 60. In step S21 above, a temperature-compensated piezoelectric vibration accelerometer is installed at the non-drive end bearing housing of the booster pump. The charge signal output by the sensor is converted into a voltage signal by a charge amplifier, and then high-frequency noise is removed by an anti-aliasing low-pass filter. The signal is then converted from analog to digital by the high-speed analog acquisition channel of the programmable logic controller (PLC) to obtain a discrete digital vibration sequence. The sampling frequency of the high-speed analog acquisition channel is set to no less than 8 times the highest impeller passing frequency, which is the product of the number of impeller blades and the pump's highest operating speed divided by 60. The non-drive end bearing housing is the optimal acquisition location for cavitation vibration signals. The temperature compensation design is suitable for LNG cryogenic conditions. The sampling frequency of 8 times the highest impeller passing frequency satisfies the Nyquist sampling theorem, avoiding spectral aliasing and ensuring the accuracy and stability of the vibration signal acquisition.

[0031] S22: Every 0.5 seconds, extract the latest fixed-length sample data from the continuous digital vibration sequence, perform a fast Fourier transform on the sample data to obtain a discrete vibration spectrum containing the amplitude of each frequency component; In step S22 above, every 0.5 seconds, the latest fixed-length sample data is extracted from the continuous digital vibration sequence, and a Fast Fourier Transform is performed on the sample data to obtain a discrete vibration spectrum containing the amplitude of each frequency component. The 0.5-second calculation period can reflect the changing trend of cavitation vibration in real time. The Fast Fourier Transform can convert the time-domain vibration signal into frequency-domain features, accurately extract the frequency band energy corresponding to cavitation, and simultaneously meet the computing power and response speed requirements of real-time control.

[0032] S23: In the discrete vibration spectrum, all spectral lines with a fixed extraction frequency range between 0.4 and 0.6 times the highest impeller passing frequency are extracted. The amplitude corresponding to each frequency component in the spectral line is squared, and all squared values ​​are summed to obtain the vibration energy in the specific frequency band. The specific frequency band corresponds to the response frequency band of the flow channel subharmonic pressure pulsation caused by initial gas erosion on the pump body. In step S23 above, all spectral lines within a fixed frequency range of 0.4 to 0.6 times the highest impeller passing frequency are extracted from the discrete vibration spectrum. The amplitude of each frequency component in the spectral line is squared, and all squared values ​​are summed to obtain the vibration energy within this specific frequency band. This specific frequency band corresponds to the response frequency band of the subharmonic pressure pulsation in the flow channel caused by initial cavitation on the pump body. The energy of initial cavitation is concentrated in this frequency band and appears earlier than the traditional blade frequency signal. Targeted extraction of energy in this frequency band can accurately identify initial cavitation and improve the sensitivity and timeliness of cavitation determination.

[0033] S24: Within the full frequency range of 10Hz to 2000Hz in the same discrete vibration spectrum, the total vibration energy of the entire frequency band is obtained by accumulating the squares using the same calculation method as in step S23. The vibration energy in the specific frequency band is divided by the total vibration energy of the entire frequency band to obtain a dimensionless ratio between 0 and 1. This ratio is the normalized cavitation erosion index, and its value is directly proportional to the intensity of cavitation erosion suffered by the impeller material at the current operating point. In step S24 above, the total vibration energy of the entire frequency band from 10Hz to 2000Hz within the same discrete vibration spectrum is obtained by squaring and summing the values, similar to step S23. The vibration energy within a specific frequency band is divided by the total vibration energy of the entire frequency band to obtain a dimensionless ratio between 0 and 1. This ratio is the normalized cavitation erosion index, and its value is directly proportional to the intensity of cavitation erosion suffered by the impeller material at the current operating point. Normalization eliminates external interference such as sensor gain and operating condition variations, ensuring the index reflects only the degree of cavitation erosion, achieving dimensionless quantification of cavitation intensity, facilitating direct comparison with calibration thresholds, and improving the versatility of cavitation assessment.

[0034] S25: Compare the normalized cavitation erosion index with the micro-erosion allowable upper limit obtained through the pad calibration test and pre-stored in the controller. When the normalized cavitation erosion index does not exceed the micro-erosion allowable upper limit, it is determined that the booster pump is currently in the cavitation safe zone. When the normalized cavitation erosion index exceeds the micro-erosion allowable upper limit, it is determined that the booster pump has entered the unacceptable cavitation zone. The comparison result serves as the basis for the judgment in steps S4 and S5.

[0035] Step S25 compares the normalized cavitation erosion index with the micro-erosion allowable upper limit obtained through the pad calibration test and pre-stored in the controller. When the normalized cavitation erosion index does not exceed the micro-erosion allowable upper limit, the booster pump is determined to be in the cavitation safety zone. When the normalized cavitation erosion index exceeds the micro-erosion allowable upper limit, the booster pump is determined to have entered the unacceptable cavitation zone. This comparison result directly serves as the basis for determining the guide vane exploration trigger and retraction. Based on the threshold calibration of the actual pad test, which matches the actual cavitation erosion characteristics of the pump, dynamic safety judgment replaces fixed boundary setting. While ensuring cavitation safety, it releases the high-efficiency operating range, providing precise safety constraints for the guide vane unidirectional step exploration.

[0036] As described in steps S21-S25 above, LNG booster pumps are prone to cavitation during operation. Cavitation directly causes impeller material erosion, affecting the service life of the equipment. Traditional control methods, to mitigate cavitation risks, set a fixed lower limit for the guide vane opening based on the worst-case operating conditions. This fixed lower limit cannot adapt to the pump's real-time operating conditions, limiting the pump's utilization of its high-efficiency operating range and exacerbating the fretting wear of the guide vane actuator due to frequent trial adjustments. Therefore, it is necessary to use pump vibration signals to perceive the actual cavitation erosion intensity in real time, construct an adaptive dynamic safety threshold, and resolve the core contradiction between fixed safety margins and guide vane actuator wear.

[0037] Existing technologies rely on theoretical net positive suction head (NPSH) calculations to set fixed cavitation safety boundaries, without considering the actual operating conditions of the pump body. The safety margin settings are overly conservative, and conventional vibration monitoring can only provide cavitation alarms, not serve as a continuous safety variable for closed-loop control. By employing a temperature-compensated piezoelectric vibration acceleration sensor to collect pump body vibration signals, and by normalizing the energy in the sub-blade frequency band corresponding to initial cavitation, a cavitation erosion index is obtained. This directly transforms vibration characteristics into a cavitation safety judgment index, achieving dynamically adaptive cavitation safety boundary constraints. By collecting pump body vibration signals and performing frequency domain analysis, a normalized cavitation erosion index is calculated, enabling real-time quantification of cavitation erosion intensity without theoretical NPSH calculations. This provides a precise dynamic safety boundary judgment basis for the safety triggering and safety retreat logic of guide vane exploration.

[0038] In one embodiment, step S3 specifically includes: S31: Define the normal silent cruise state. In this state, the set angle of the adjustable guide vane is locked by the controller to the locked angle value stored after the most recent successful exploration. The controller stops outputting any new position commands to the hydraulic or servo actuator of the adjustable guide vane. The actuator of the adjustable guide vane is in a static state of power-off and position preservation, and does not produce any mechanical displacement. Step S31 above defines a normal silent cruise state. In this state, the set angle of the adjustable guide vane is locked by the controller to the locked angle value stored after the most recent successful exploration. The controller stops outputting any new position commands to the hydraulic or servo actuator of the adjustable guide vane, and the actuator of the adjustable guide vane is in a power-off and position-maintaining static state, without any mechanical displacement. This design keeps the guide vane stationary for most of the operating time, directly avoiding the fretting wear of the guide vane actuator in low-temperature environments, and ensuring long-term stable operation of the actuator.

[0039] S32: In silent cruise mode, the controller receives the real-time outlet pressure signal from the pressure transmitter installed on the pump outlet pipeline. It subtracts the real-time outlet pressure signal from the preset target outlet pressure value to obtain the pressure deviation. The pressure deviation is a core input parameter for motor speed regulation, accurately reflecting the actual fluctuation range of the outlet pressure and providing a precise basis for subsequent closed-loop speed regulation.

[0040] S33: Using the pressure deviation as input, run the incremental proportional-integral-derivative control algorithm, calculate the required motor speed increment based on the current value of the pressure deviation, the historical cumulative value of the deviation, and the deviation change trend, and convert the current motor speed into the motor speed increment after superimposing the motor speed increment into the frequency control command or speed control command of the frequency converter, and send it to the frequency converter through the communication bus or analog output interface. Step S33 above uses the pressure deviation as input and runs an incremental proportional-integral-derivative (PID) control algorithm. Based on the current value of the pressure deviation, the historical cumulative value of the deviation, and the deviation change trend, it calculates the required motor speed increment. The current motor speed is then superimposed with the motor speed increment and converted into a frequency control command or speed control command for the inverter, which is sent to the inverter via the communication bus or analog output interface. The IPD algorithm has a fast response speed and no integral saturation problem, making it suitable for scenarios with random load fluctuations in LNG refueling stations. It can accurately output speed adjustment commands, ensuring the stability and speed of outlet pressure regulation.

[0041] S34: The frequency converter adjusts the actual speed of the motor in real time according to the received frequency control command or speed control command. The change in motor speed causes the output flow and outlet pressure of the booster pump to change accordingly, so as to compensate for the pressure fluctuation caused by the change of downstream gas supply load, so that the outlet pressure is maintained near the target outlet pressure value. During the entire dynamic pressure adjustment process, the angle of the adjustable guide vane remains locked.

[0042] In step S34 above, the frequency converter adjusts the actual motor speed in real time according to the received frequency control command or speed control command. The change in motor speed causes a corresponding change in the output flow and outlet pressure of the booster pump to compensate for pressure fluctuations caused by changes in downstream gas filling load, keeping the outlet pressure near the target outlet pressure value. Throughout the entire dynamic pressure adjustment process, the angle of the adjustable guide vane remains locked. This allows for rapid and stable adjustment of the outlet pressure while keeping the guide vane position unchanged throughout the process, meeting the pressure control requirements for LNG filling and continuously protecting the guide vane actuator, thus achieving dual protection of control performance and equipment lifespan.

[0043] As described in steps S31-S34 above, LNG refueling vehicles arrive randomly at LNG refueling stations, causing frequent fluctuations in the downstream load of the booster pump. This directly leads to rapid changes in the pump outlet pressure, requiring a rapid response from the control system to maintain stable outlet pressure. The low-temperature environment of LNG causes the sealing materials of the guide vane hydraulic or servo actuators to harden. High-frequency, small-amplitude reciprocating motions can easily cause micro-wear and failure of the actuators. Therefore, it is necessary to decouple the rapid adjustment of outlet pressure from the optimal adjustment of guide vane efficiency. The dynamic adjustment of pressure is completed by the motor speed, and the guide vane only performs a single action when necessary, thus resolving the core contradiction between the need for stable outlet pressure and the service life of the guide vane actuator.

[0044] Existing technologies couple outlet pressure regulation with guide vane efficiency regulation, causing the guide vanes to frequently make small adjustments based on pressure and flow signals. Under cryogenic LNG conditions, the guide vane actuator sealing material wears rapidly, leading to failure and degradation within months. The above steps completely separate pressure closed-loop control from guide vane position control. Under normal conditions, the guide vane angle is locked, and the guide vane actuator remains stationary even when powered off. Outlet pressure stability is achieved solely through incremental PID regulation of the motor speed, significantly reducing the number of guide vane actuator movements and eliminating the problem of high-frequency fretting wear from the control logic perspective. By setting a normal silent cruise state, the adjustable guide vane angle is mechanically locked, and outlet pressure stability is achieved solely through frequency converter-regulated motor speed. This keeps the guide vane actuator in a stationary state for extended periods, meeting the dynamic adjustment requirements of the LNG booster pump outlet pressure while preventing fretting wear of the guide vane actuator from a mechanical perspective, thus extending equipment lifespan.

[0045] In one embodiment, step S4 specifically includes: S41: During the silent cruise in step S3, the controller acquires the power factor fluctuation calculated in step S1 and the normalized cavitation erosion index calculated in step S2 in parallel and continuously, and continuously monitors both. During the silent cruise, the controller acquires the power factor fluctuation calculated in step S1 and the normalized cavitation index calculated in step S2 in parallel and continuously. These two parameters are the core criteria for determining the guide vane exploration trigger. Parallel monitoring can ensure the real-time and synchronization of the trigger logic and provide stable data support for dual-condition determination.

[0046] S42: Set the first threshold for judging deviation from the high-efficiency pre-selected area to 1.2 times the preset fluctuation threshold, set the second threshold for judging sufficient cavitation safety margin to 0.5 times the upper limit of micro-erosion, start a timer, and when the power factor fluctuation is detected to be greater than the first threshold and the normalized cavitation erosion index is less than the second threshold for the first time, the timer starts counting from zero. If the two conditions are met continuously and the timer value reaches 30 consecutive seconds, the guide vane exploration trigger condition is determined to be met, the timer is reset to zero and the exploration preparation state is entered. If any condition is no longer met during the timing process, the timer will be immediately reset to zero, and the timing will restart from zero when both conditions are met simultaneously again. In step S42 above, the first threshold for judging deviation from the high-efficiency pre-selected zone is set to 1.2 times the preset fluctuation threshold, and the second threshold for judging sufficient cavitation safety margin is set to 0.5 times the upper limit of micro-erosion allowance. A timer is used to time the continuous satisfaction of the two conditions. The trigger condition is determined to be established only when the two conditions are continuously satisfied for 30 seconds. If either condition is not satisfied during the timing process, the timer is immediately reset to zero and recalculated. This design can eliminate false triggering caused by instantaneous operating condition fluctuations, ensuring that the guide vane only starts exploration when the efficiency continuously deviates and the safety margin is sufficient, thus improving the reliability of the triggering logic.

[0047] S43: After determining that the guide vane exploration trigger condition is met, the controller calculates a new target value for the adjustable guide vane angle. The new target value for the adjustable guide vane angle is equal to the currently locked adjustable guide vane angle minus the preset fixed step value. The step direction represented by this calculation is to reduce the opening of the adjustable guide vane, so that the working point of the booster pump moves closer to the cavitation safety boundary. After the triggering condition of step S43 is met, the controller subtracts the preset fixed step value from the currently locked adjustable guide vane angle to obtain a new target value for the adjustable guide vane angle. The stepping direction corresponding to this calculation is to reduce the opening of the adjustable guide vane, so that the working point of the booster pump moves closer to the cavitation safety boundary. The unidirectional fixed step design can avoid the guide vane from reciprocating oscillation, ensuring that the exploration direction always points to the safer area with higher efficiency, which is in line with the core control logic of the invention of unidirectional optimization.

[0048] S44: The controller issues a one-time adjustable guide vane angle command, sends the new adjustable guide vane angle target value to the hydraulic or servo actuator of the adjustable guide vane, drives the adjustable guide vane to complete the unidirectional stepping of the preset fixed step value, and after the adjustable guide vane reaches the designated position, the controller immediately stops command updating, relocks the adjustable guide vane to the new angle, completes one unidirectional exploration action, and waits for the determination of step S5.

[0049] In step S44 above, the controller issues a one-time adjustable guide vane angle command, driving the actuator to complete a unidirectional stepping motion with a preset fixed step value. Once the guide vane reaches the designated position, the command update stops and the actuator relocks. This execution method is a single, instantaneous action, without continuous power supply or repeated adjustment processes, further reducing mechanical wear. After completing the exploration action, the actuator waits for the cavitation safety determination in step S5, forming a complete exploration execution closed loop.

[0050] As described in steps S41-S44 above, the LNG booster pump needs to operate in the high-efficiency range near the cavitation safety boundary for a long time. Too frequent guide vane adjustments will cause micro-motion wear of the actuator, and improper adjustment timing may directly enter the cavitation danger zone. Therefore, it is necessary to set strict trigger constraints for guide vane exploration. Only when the pump deviates significantly from the high-efficiency range and has sufficient cavitation safety margin is a guide vane stepping action allowed to be performed once, balancing the efficiency optimization requirements with the guide vane actuator service life requirements.

[0051] Existing technologies employ extreme value search methods using continuous micro-perturbation or high-frequency small-amplitude probing. This results in continuous operation of the guide vane actuator, leading to rapid seal wear and failure under LNG cryogenic conditions. Furthermore, the triggering logic does not incorporate real-time cavitation safety status, making it prone to blindly adjusting towards the cavitation boundary. The aforementioned steps utilize a dual-condition continuous judgment mechanism, triggering only when efficiency deteriorates and safety margins are sufficient. This executes a single, unidirectional, large-step movement, eliminating frequent micro-motion wear from both the triggering logic and execution method, while simultaneously ensuring cavitation safety during the exploration process. Through continuous monitoring and judgment of both efficiency deviation and cavitation safety conditions, a single, unidirectional, fixed-amplitude guide vane adjustment is performed when strict triggering conditions are met. This achieves low-frequency, high-safety guide vane exploration triggering and execution, minimizing the number of guide vane actuator movements while ensuring optimal efficiency.

[0052] In one embodiment, step S5 specifically includes: S51: Starting from the completion and relocking of the adjustable guide vane unidirectional stepping in step S4, a stabilization waiting timer is started for 2 seconds. After the stabilization waiting timer ends and the dynamic process of the booster pump has become stable, the vibration acceleration signal is reacquired, a fast Fourier transform is performed, the vibration energy of a specific frequency band and the total vibration energy of the entire frequency band are extracted and the ratio is calculated to obtain the normalized cavitation erosion index after stepping. In step S51 above, when the guide vane completes unidirectional stepping and relocks, a 2-second stabilization waiting timer is started. After the timer expires, the normalized cavitation erosion index after stepping is reacquired according to the signal acquisition and calculation method in step S2. The 2-second stabilization waiting time can eliminate mechanical movement and hydraulic dynamic disturbances of the guide vane, ensuring that the cavitation index can truly reflect the steady-state cavitation state of the pump and improve the accuracy of cavitation safety judgment.

[0053] S52: Compare the newly obtained normalized cavitation erosion index after stepping with the micro-erosion allowable upper limit: If the normalized cavitation erosion index after stepping does not exceed the micro-erosion allowable upper limit, it means that the adjustable guide vane exploration is successful and it has safely entered the high-efficiency area closer to the cavitation boundary. The controller will overwrite the current adjustable guide vane angle with the new locked angle value, and at the same time clear the trigger state and all related timers. The system will unconditionally return to the silent cruise state described in step S3. In step S52, the normalized cavitation erosion index after stepping is compared with the upper limit of micro-erosion. If the upper limit is not exceeded, the exploration is considered successful. The controller stores the current guide vane angle as a new locked angle value, clears the trigger state and related timers, and the system returns to silent cruise state. This design can solidify the safe and efficient guide vane position into a normal locked value, improving pump operating efficiency while ensuring cavitation safety, and reducing mechanical wear by eliminating unnecessary actuator movements.

[0054] S53: If the normalized cavitation erosion index after stepping exceeds the upper limit of micro-erosion, it indicates that the current adjustable guide vane exploration has reached an unacceptable cavitation zone. At this point, a safety retraction mechanism is immediately triggered, calculating the retraction angle value. The retraction angle value is equal to the current adjustable guide vane angle after stepping plus twice the preset fixed step value. The controller outputs a retraction angle command to rapidly increase the adjustable guide vane opening with a large step, pulling the booster pump's operating point back to a safe depth. If the normalized cavitation erosion index after stepping exceeds the upper limit of micro-erosion, the safety retraction mechanism is immediately triggered, adding twice the preset fixed step value to the current guide vane angle to obtain the retraction angle. The controller outputs a command to drive the guide vane to complete a large reverse step, quickly pulling the pump's operating point back to a safe depth of cavitation. A reverse retraction with a step size of 2 can quickly escape the cavitation danger zone, preventing continuous cavitation damage to the impeller. The large unidirectional movement without small reciprocating motion further protects the guide vane actuator.

[0055] S54: After the rollback is executed, the locked position of the adjustable guide vane angle after the rollback is recorded as the exploration-prohibited position, and a 24-hour exploration-prohibited timer is started in the programmable logic controller. During the period when the exploration-prohibited timer is not zeroed, even if the guide vane exploration triggering condition specified in step S4 is met again, it is prohibited to initiate a new guide vane exploration in the direction of decreasing adjustable guide vane opening. After the exploration-prohibited timer ends, the historical mark of the position is automatically cleared and the normal exploration qualification is restored.

[0056] After the above step S54 is completed, the retreat position is recorded as a no-exploration position, and a 24-hour no-exploration timer is started. During the timer, new explorations are prohibited in the direction of decreasing guide vane opening. After the timer ends, the no-exploration mark is automatically cleared, and normal exploration privileges are restored. The 24-hour no-exploration duration can completely avoid repeated attempts in a short period of time, eliminating the problem of high-frequency micro-motion wear of the guide vane actuator from the algorithm level, which is in line with the core design goal of this invention to extend the service life of the actuator.

[0057] As described in steps S51-S54 above, when the LNG booster pump performs a unidirectional step exploration towards the cavitation boundary, it may exceed the safety boundary due to sudden changes in operating conditions, causing impeller cavitation and erosion. If a small retreat or repeated attempts are made after the exploration exceeds the limit, the fretting wear of the guide vane actuator will be aggravated again. Therefore, it is necessary to complete the steady-state cavitation verification after stepping, perform a rapid and large retreat for the over-limit state, and set a long-term exploration prohibition constraint to balance the core contradiction between efficiency optimization and cavitation safety and actuator life.

[0058] Existing technologies often employ small-amplitude retraction or continuous trial correction when guide vane exploration exceeds limits. This leads to high-frequency reciprocating motions in the guide vane actuator, causing rapid failure under LNG cryogenic conditions. Furthermore, the lack of a no-exploration mechanism means that repeated trials within a short period continuously impact cavitation safety boundaries. The proposed solution employs steady-state verification after stepping, a double-step reverse retraction for exceeding limits, and a 24-hour no-exploration zone to achieve a safe closed loop for each exploration. This eliminates the wear and tear caused by reciprocating motions and short-term repeated trials from the control logic perspective. By implementing steady-state waiting after guide vane stepping, cavitation safety verification, successful position locking, and large-scale reverse retraction and long-term no-exploration settings for exceeding limits, a complete safety closed loop for the entire guide vane exploration process is achieved. This ensures that each guide vane adjustment is within the cavitation safety range, while simultaneously preventing reciprocating micro-motions and short-term repeated trials by the guide vane actuator, guaranteeing long-term stable equipment operation.

[0059] like Figure 2 As shown, the present invention also discloses an LNG intelligent impeller booster pump regulation and control system, comprising: The acquisition module is used to acquire the motor electrical parameters output by the frequency converter driving the booster pump, extract time-domain features from the motor electrical parameters, generate efficiency trend criteria, and determine that the booster pump is in the high-efficiency pre-selection zone when the efficiency trend criteria meet the preset high-efficiency zone conditions. The acquisition module is used to acquire the vibration signal of the booster pump, perform frequency domain processing on the vibration signal, and extract the ratio of the energy component of the preset characteristic frequency band to the energy component of the full frequency band as a cavitation safety criterion. The control module is used to lock the adjustable guide vane at the current angle when the guide vane exploration is not triggered, and adjust the speed of the motor according to the deviation between the pump outlet pressure and the target outlet pressure through the frequency converter. The monitoring module is used to continuously monitor the efficiency trend criterion and the cavitation safety criterion. When both meet the preset exploration triggering conditions simultaneously within a preset time period, the module controls the adjustable guide vane to perform a preset step size reduction adjustment. The correction module is used to reacquire the cavitation safety criterion after the opening reduction adjustment is completed. If the reacquired cavitation safety criterion does not exceed the preset safety limit, the adjusted guide vane angle is locked and the state of no guide vane exploration is returned. If the safety limit is exceeded, the adjustable guide vane is controlled to perform an opening increase adjustment with a preset backtracking step, and the backtracked position is marked as a prohibited exploration area within a preset time period.

[0060] In one embodiment, the control module includes: The definition unit is used to define the silent cruise state, in which the set angle of the adjustable guide vane is maintained at the angle value stored after the most recent successful exploration, and the guide vane angle update command is prohibited. The acquisition unit is used to acquire the real-time outlet pressure signal fed back by the pressure transmitter on the pump outlet pipeline, and calculate the pressure deviation based on the real-time outlet pressure signal and the preset target outlet pressure. The instruction generation unit is used to take the pressure deviation as input, execute the feedback control algorithm, generate a speed adjustment instruction, and execute it through the frequency converter, so as to keep the angle of the adjustable guide vane unchanged during the motor speed adjustment process.

[0061] This application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described LNG intelligent impeller booster pump regulation and control method.

[0062] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described LNG intelligent impeller booster pump regulation and control method.

[0063] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in this application and in the embodiments can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual-speed SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0064] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0065] The above description is merely a preferred embodiment of the present invention and does not limit the scope of this application. Any equivalent results or equivalent process transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of protection of this application.

Claims

1. A method for regulating and controlling an intelligent impeller booster pump for LNG, characterized in that, Includes the following steps: The motor electrical parameters output by the frequency converter driving the booster pump are obtained, the time-domain features of the motor electrical parameters are extracted, and an efficiency trend criterion is generated. When the efficiency trend criterion meets the preset high-efficiency zone conditions, the booster pump is determined to be in the high-efficiency pre-selection zone. The vibration signal of the booster pump is collected, and the vibration signal is processed in the frequency domain to extract the ratio of the energy component of the preset characteristic frequency band to the energy component of the full frequency band, which is used as the cavitation safety criterion. Without triggering guide vane exploration, the adjustable guide vane is locked at the current angle, and the motor speed is adjusted by the frequency converter according to the deviation between the pump outlet pressure and the target outlet pressure. The efficiency trend criterion and the cavitation safety criterion are continuously monitored. When both meet the preset exploration triggering conditions within a preset time period, the adjustable guide vane is controlled to perform a preset step size reduction adjustment. After the opening reduction adjustment is completed, the cavitation safety criterion is reacquired. If the reacquired cavitation safety criterion does not exceed the preset safety limit, the adjusted guide vane angle is locked and the state of non-triggered guide vane exploration is returned. If the safety limit is exceeded, the adjustable guide vane is controlled to perform an opening increase adjustment with a preset backtracking step, and the backtracked position is marked as a prohibited exploration area within a preset time period.

2. The LNG intelligent impeller booster pump regulation and control method according to claim 1, characterized in that, The step of extracting time-domain features from the motor electrical parameters and generating efficiency trend criteria includes: The current active power and reactive power values ​​of the motor are obtained from the frequency converter at fixed intervals, and the real-time power factor is calculated. A sliding window of a preset duration is constructed, and continuous real-time power factor values ​​and active power sample values ​​are stored within the sliding window. The fluctuation of the real-time power factor values ​​within the window is calculated, and the response steepness is determined based on the changes in the active power sample values ​​within the window. The real-time power factor, the volatility, and the response steepness are compared with preset power factor thresholds, volatility thresholds, and response steepness thresholds, respectively. When all three simultaneously meet the corresponding threshold conditions, the booster pump is determined to be in the high-efficiency pre-selection zone.

3. The LNG intelligent impeller booster pump regulation and control method according to claim 1, characterized in that, The step of performing frequency domain processing on the vibration signal to extract the ratio of the energy component of a preset characteristic frequency band to the energy component of the entire frequency band includes: Vibration acceleration signals are collected at a preset position on the booster pump body, and the vibration acceleration signals are subjected to spectral transformation to obtain discrete vibration spectra. In the discrete vibration spectrum, all spectral lines within the characteristic frequency band are extracted according to the preset sub-leaf frequency range, the vibration energy within the characteristic frequency band is calculated, and the total vibration energy of the entire frequency band of the discrete vibration spectrum is calculated. The vibration energy within the characteristic frequency band is divided by the total vibration energy across the entire frequency band to obtain a dimensionless ratio, which is used as the cavitation safety criterion.

4. The LNG intelligent impeller booster pump regulation and control method according to claim 1, characterized in that, The step of adjusting the motor speed via the frequency converter based on the deviation between the pump outlet pressure and the target outlet pressure includes: Define a silent cruise state, in which the set angle of the adjustable guide vane is maintained at the angle value stored after the most recent successful exploration, and the guide vane angle update command is prohibited; Obtain the real-time outlet pressure signal fed back by the pressure transmitter on the pump outlet pipeline, and calculate the pressure deviation based on the real-time outlet pressure signal and the preset target outlet pressure. Using the pressure deviation as input, a feedback control algorithm is executed to generate a speed adjustment command, which is then executed through the frequency converter, keeping the angle of the adjustable guide vane constant during the motor speed adjustment process.

5. The LNG intelligent impeller booster pump regulation and control method according to claim 1, characterized in that, The step of controlling the adjustable guide vane to perform a preset step size reduction adjustment when both conditions simultaneously meet the preset exploration triggering conditions within a preset time period includes: During silent cruise, the latest determined efficiency trend criterion and cavitation safety criterion are acquired in parallel and continuously monitored. Set a first threshold and a second threshold. When the fluctuation in the efficiency trend criterion is detected to increase and the cavitation safety criterion indicates that the safety margin is sufficient, start timing. If the state is maintained continuously for a preset confirmation time, it is determined that the exploration trigger condition is met. After the exploration triggering condition is met, the target angle for reducing the opening is determined based on the currently locked guide vane angle and the preset step size, and the adjustable guide vane is controlled to perform a single adjustment and relock.

6. The LNG intelligent impeller booster pump regulation and control method according to claim 1, characterized in that, The step of re-acquiring the cavitation safety criterion after the opening reduction adjustment is completed includes: After the adjustable guide vane completes the opening reduction adjustment and relocks, wait for the preset stabilization time, re-acquire the vibration signal, and calculate the adjusted cavitation safety criterion. The adjusted cavitation safety criterion is compared with the safety limit. If the limit is not exceeded, the current guide vane angle is stored as a new locked angle, and the system returns to silent cruise mode. If the opening is exceeded, the retraction angle for increasing the opening is determined based on the current guide vane angle and the preset retraction step length. The adjustable guide vane is then controlled to perform retraction adjustment, and the retracted guide vane position is marked as a no-exploration position. Exploration in the direction of decreasing opening is prohibited within the preset no-exploration time.

7. An LNG intelligent impeller booster pump regulation and control system, characterized in that, include: The acquisition module is used to acquire the motor electrical parameters output by the frequency converter driving the booster pump, extract time-domain features from the motor electrical parameters, generate efficiency trend criteria, and determine that the booster pump is in the high-efficiency pre-selection zone when the efficiency trend criteria meet the preset high-efficiency zone conditions. The acquisition module is used to acquire the vibration signal of the booster pump, perform frequency domain processing on the vibration signal, and extract the ratio of the energy component of the preset characteristic frequency band to the energy component of the full frequency band as a cavitation safety criterion. The control module is used to lock the adjustable guide vane at the current angle when the guide vane exploration is not triggered, and adjust the speed of the motor according to the deviation between the pump outlet pressure and the target outlet pressure through the frequency converter. The monitoring module is used to continuously monitor the efficiency trend criterion and the cavitation safety criterion. When both meet the preset exploration triggering conditions simultaneously within a preset time period, the module controls the adjustable guide vane to perform a preset step size reduction adjustment. The correction module is used to reacquire the cavitation safety criterion after the opening reduction adjustment is completed. If the reacquired cavitation safety criterion does not exceed the preset safety limit, the adjusted guide vane angle is locked and the state of no guide vane exploration is returned. If the safety limit is exceeded, the adjustable guide vane is controlled to perform an opening increase adjustment with a preset backtracking step, and the backtracked position is marked as a prohibited exploration area within a preset time period.

8. The LNG intelligent impeller booster pump regulation and control system according to claim 7, characterized in that, The control module includes: The definition unit is used to define the silent cruise state, in which the set angle of the adjustable guide vane is maintained at the angle value stored after the most recent successful exploration, and the guide vane angle update command is prohibited. The acquisition unit is used to acquire the real-time outlet pressure signal fed back by the pressure transmitter on the pump outlet pipeline, and calculate the pressure deviation based on the real-time outlet pressure signal and the preset target outlet pressure. The instruction generation unit is used to take the pressure deviation as input, execute the feedback control algorithm, generate a speed adjustment instruction, and execute it through the frequency converter, so as to keep the angle of the adjustable guide vane unchanged during the motor speed adjustment process.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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