Method and system for identifying friction loss of gravity energy storage based on motor electrical signals

Abstract

The application discloses a method and system for identifying friction loss of gravity energy storage based on motor electrical signals, which collects three-phase current and rotation speed of the motor to calculate electromagnetic torque and total load torque, decomposes total friction torque into independent loss components such as steel wire rope-pulley, guide rail-guide wheel and bearing by using a multi-source friction decoupling model, and updates model parameters on line through recursive least squares. The application can identify multi-source friction loss on line in real time without additional sensors, only by using existing motor electrical signals, and provides key data support for efficiency optimization and predictive maintenance of gravity energy storage, and has the advantages of low cost, good real-time performance and strong universality.

Description

Technical Field

[0001] This invention relates to the field of gravity energy storage system condition monitoring and energy efficiency optimization technology, and in particular to a method and system for identifying frictional losses in gravity energy storage based on motor electrical signals. Background Technology

[0002] Gravity energy storage systems convert electrical energy into potential energy by lifting and lowering objects weighing several to tens of tons. Their transmission system typically includes multiple friction pairs such as winches, wire ropes, pulley blocks, guide rails, and bearings. During long-term operation, frictional losses not only significantly affect the system's reciprocating efficiency (an increase of 0.01 in the coefficient of friction can lead to a 1% to 6% decrease in efficiency), but also accelerate component wear and increase maintenance costs.

[0003] Currently, the assessment of friction loss mainly relies on the following methods: (1) Offline disassembly and inspection method: After the machine is stopped, torque or stress gauges are used for measurement, which is costly, inefficient and cannot achieve monitoring; (2) Additional sensor method: Vibration and temperature sensors are installed on the transmission components, but this increases hardware costs and wiring complexity; (3) Motor parameter identification method: such as the online identification method for mechanical parameters of permanent magnet synchronous motor disclosed in application number CN201510065322.9, which can only identify the rotational inertia and viscous friction coefficient of the motor body, and cannot further decompose the load torque into the friction loss components of each component in the transmission system. (4) Adaptive lubrication control method: such as the adaptive control method and system of gravity energy storage lubrication device disclosed in application number CN117055344A, which focuses on adjusting the lubrication amount through vibration signal rather than quantitative estimation of loss.

[0004] Therefore, there is an urgent need for a method that can separate and quantify the frictional losses of various components in a gravity energy storage transmission system in real time without additional hardware. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to use the existing electrical signals of the motor control system to identify the multi-source friction loss components of the wire rope, guide rail-guide wheel, winch bearing, etc. in the gravity energy storage transmission system in real time and track their changing trends without adding sensors.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: A method for identifying frictional losses in gravity-based energy storage based on motor electrical signals is provided, including the following steps: S1: Signal Acquisition and Preprocessing: Real-time acquisition of the three-phase current of the permanent magnet synchronous motor. and rotational speed Calculate the q-axis current and electromagnetic torque; S2: Calculation of electromagnetic torque and total load torque: Solving for real-time total load torque based on the motor motion equation; S3: No-load friction calibration: With no load attached, run the lifting mechanism at different speeds and record the total load torque. Since the gravitational component of the heavy object is zero, this torque comes from the no-load frictional torque of the transmission system. Establish the relationship curve between no-load friction torque and speed. ; S4: Extraction of total frictional torque during load operation: Total load torque during normal operation with a loaded load. Including the gravitational component torque, the total frictional torque of the transmission system, and the acceleration torque, the total frictional torque of the transmission system is calculated by subtracting the gravitational component torque and the acceleration torque from the total load torque based on this relationship. ; S5: Multi-source friction loss decoupling: The lifting process of heavy objects is divided into multiple intervals according to the load size. Taking advantage of the different contribution ratios of each friction pair under different loads, a multi-source friction decoupling model is established. S6: Online Update and Trend Monitoring: Updates the model parameters of each friction component online, outputs the current value and rate of change of each friction loss component, and issues an early warning when a component exceeds a preset threshold.

[0007] Furthermore, in step S1, the electromagnetic torque calculation formula is as follows:

[0008] in, This represents the number of pole pairs of the motor. It is a permanent magnet flux linkage.

[0009] Furthermore, in step S2, the formula for calculating the real-time total load torque is:

[0010] in, The total moment of inertia of the system. The coefficient of viscous friction of the motor.

[0011] Furthermore, in step S4, the formula for calculating the gravitational component torque is: For vertical lifting, according to the formula Calculate, where, For the mass of the heavy object, Where is the radius of the drum. The reduction ratio, For transmission efficiency; For ramp-type lifting systems, according to the formula Calculate, where, The slope angle is [value].

[0012] Furthermore, in step S4, the method for extracting the total frictional torque is performed during the uniform speed operation segment, at which time the acceleration term... The calculation formula is: .

[0013] Furthermore, in step S5, the total frictional torque is decomposed into:

[0014] in: The bending and friction components of the wire rope with the pulley are directly proportional to the tension of the wire rope. The friction component between the guide rail and the guide wheel is related to the normal force of the guide wheel; The friction component of the winch and pulley bearings is related to the rotational speed. The velocity-related components are separated using the no-load calibration results from step S3. The coefficients of each component are fitted using the least squares method with measured data from different load stages.

[0015] Specifically, in a shaft system, the total frictional torque also includes the friction of the seals. .

[0016] Furthermore, in step S6, the friction model parameters are updated online using recursive least squares or Kalman filtering algorithms to adapt to changes in lubrication status and wear degree.

[0017] An online identification system for friction loss in a gravity energy storage transmission system based on electrical signals from a permanent magnet synchronous motor includes: The signal acquisition module is used to acquire the three-phase current, speed, and position or speed of the load of the permanent magnet synchronous motor. The electromagnetic torque calculation module is used to calculate the real-time electromagnetic torque based on the q-axis current. The load torque calculation module is used to calculate the total load torque based on the motor motion equation; The friction calibration module is used to perform no-load calibration and extract total friction force under load conditions. A multi-source friction decoupling module is used to decompose the total friction torque into multiple independent loss components; An online update module is used to dynamically correct model parameters; The output and early warning module is used to display each friction loss component and provide threshold alarms.

[0018] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements an online identification method for friction loss in a gravity energy storage transmission system based on electrical signals from a permanent magnet synchronous motor.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention utilizes the existing three-phase current and speed signals of the permanent magnet synchronous motor control system. Through Parker transformation and motor motion equation, online identification of friction loss can be achieved without the need for additional torque meters, vibration sensors, or temperature sensors, thus reducing monitoring costs. 2. This invention can operate continuously during each lifting and lowering process of the gravity energy storage system, and output the total friction torque of the transmission system and each friction loss component in real time, reflecting the dynamic changes of friction loss, and providing a data basis for energy efficiency optimization and predictive maintenance; 3. This invention decomposes the total frictional torque of the gravity energy storage transmission system online into multiple independent components such as the wire rope-pulley friction component, the guide rail-guide wheel friction component, the bearing friction component, and the seal friction component. By combining no-load calibration and load measurement data, decoupling is achieved by utilizing the physical characteristics that the contribution ratio of each friction pair is different under different loads. This can accurately locate high-loss components and guide targeted maintenance. 4. The technical solution of the present invention is applicable to gravity energy storage systems with various structural forms such as tower vertical lifting, inclined slope, and vertical shaft. For different configurations, only the calculation formula of gravity component torque and the component composition in the multi-source friction decoupling model need to be adjusted. The core algorithm does not need to be changed, and it has good portability and versatility. 5. This invention uses recursive least squares (RLS) or Kalman filtering algorithms to update friction model parameters online, which can adaptively track dynamic processes such as changes in lubrication status and increased wear. When a certain friction loss component exceeds a preset threshold, the system automatically issues an early warning, thus realizing predictive maintenance. 6. This invention can be used in conjunction with the online identification method of heavy object mass based on the steady-state component of q-axis current. It can accurately calculate the gravitational component torque without independently marking the object mass, thereby further improving the accuracy and automation of friction loss identification. Attached Figure Description

[0020] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is the overall flowchart; Figure 2 System structure block diagram; Figure 3 This is a schematic diagram of a multi-source friction decoupling model; Figure 4Logic diagram for online updates and early warnings. Detailed Implementation

[0021] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments. Example 1:

[0023] This embodiment takes a lifting channel of a 2MW tower-type vertical lifting gravity energy storage system as an example to provide a detailed description of the online identification method for friction loss of gravity energy storage transmission system based on permanent magnet synchronous motor electrical signals provided by the present invention.

[0024] In this embodiment, the drive motor is a permanent magnet synchronous motor (PMSM) with a rated power of 250kW, and the number of pole pairs of the motor is... Permanent magnet magnetic flux The total rotational inertia J of the system (converted to the motor shaft) was calibrated to 120 kg·m² through a no-load start-up test. The motor's viscous friction coefficient... .

[0025] (1) Signal acquisition and preprocessing The three-phase current of the permanent magnet synchronous motor is collected in real time through the motor control system. and rotational speed (Speed ​​can be obtained through an encoder or resolver). The three-phase current is converted into d-axis current in a rotating coordinate system using the Park transformation. and q-axis current In the usual Under the vector control strategy, electromagnetic torque Only with Proportional. In this embodiment, the q-axis current is measured during the uniform lifting phase. =880A.

[0026] (2) Calculation of electromagnetic torque and total load torque Electromagnetic torque: in, This represents the number of pole pairs of the motor. The flux linkage of the permanent magnet is known.

[0027] Solve the real-time total load torque based on the motor's motion equations. ,in, The total moment of inertia of the system (can be calibrated offline through an unloaded start-up experiment). This is the motor's viscous friction coefficient (which can be obtained from the motor manual or identified online).

[0028] In this embodiment, electromagnetic torque.

[0029] During the uniform motion phase, the acceleration term Given the rotational speed ω = 2.2 rad / s, substituting the values, we get: .

[0030] (3) No-load friction calibration When no load is attached, the vehicle runs at a constant speed of 0.5, 1.0, 1.5, and 2.0 m / s, and the corresponding steady-state values ​​of the q-axis current are recorded. The unloaded friction torque is then calculated. Since the gravitational component of the heavy object is zero, this torque comes from the no-load frictional torque of the transmission system. Establish the relationship curve between no-load friction torque and speed. .

[0031] The relationship between the no-load friction torque and the velocity obtained by fitting in this embodiment is as follows: (Unit: N·m) (4) Extraction of total frictional torque during load operation When the load is running normally, the total load torque Including the gravitational component torque, the total frictional torque of the transmission system, and the acceleration torque, the total frictional torque of the transmission system is calculated by subtracting the gravitational component torque and the acceleration torque from the total load torque based on this relationship. .

[0032] First, calculate the torque of the gravitational component. For vertical lifting, use the formula... Calculation. Among them, the mass of the heavy object. The method obtained by online identification based on the steady-state component of the q-axis current (measured in this embodiment) is as follows: Calculate ), roll radius Reduction ratio Transmission efficiency ,but:

[0033] During the uniform motion phase, the acceleration term The formula for calculating the total frictional torque is: .

[0034] (5) Decoupling of multi-source friction loss The lifting process of heavy objects is divided into multiple intervals according to the load size. Taking advantage of the different contribution ratios of each friction pair under different loads, a multi-source friction decoupling model is established.

[0035] Specifically, the total frictional torque is decomposed into:

[0036] in: The bending and friction components of the wire rope with the pulley are directly proportional to the tension of the wire rope (approximately equal to the weight of the object). The friction component between the guide rail and the guide wheel is related to the normal force of the guide wheel (affected by the off-center load of the heavy object); The friction component of the winch and pulley bearings is mainly related to the rotational speed.

[0037] The velocity-related components are separated using the no-load calibration results from step S3. The coefficients of each component are then fitted using the least squares method based on measured data from different load stages. In this embodiment, the no-load friction torque at the same speed is approximately 50 + 20 × 2.2 ≈ 94 N·m. The friction torque obtained from the no-load calibration is significantly higher than the total friction torque extracted under load conditions, indicating that the no-load calibration results cannot be directly used under load conditions. This is because the increased tension in the wire rope under load alters the contact stress state of the pulley bearings, necessitating recalibration of each friction component under load. Improved method: By performing multiple uniform speed runs at different heights (different wire rope suspension lengths), the bending friction component of the wire rope and the bearing friction component are separated by utilizing the variation in pulley friction when the wire rope tension changes. Specifically: Measurements were taken at the bottom of the shaft (where the wire rope is shorter) and the top of the shaft (where the wire rope is longer) to establish the relationship between friction and wire rope length, thereby separating the wire rope friction component (proportional to length) and the bearing friction component (related to rotational speed).

[0038] The frictional loss between the wire rope and pulley was identified as approximately 35 N·m, the frictional loss of the guide rail was approximately 12 N·m, and the frictional loss of the bearing and seal was approximately 11 N·m. The system outputs each loss component and records its changing trend.

[0039] (6) Online updates and trend monitoring The recursive least squares (RLS) algorithm is used to update the model parameters of each friction component online to adapt to changes in lubrication conditions and increased wear. After each lift / lowering cycle, the system outputs the current value and rate of change of each friction loss component.

[0040] When the friction component of the wire rope-pulley increases by more than 20% during 10 consecutive lifting and lowering operations, the system issues a warning of "poor wire rope lubrication or pulley wear," prompting maintenance personnel to check.

[0041] The overall process of this embodiment is as follows: Figure 1 As shown, the system structure is as follows: Figure 2 As shown, the multi-source friction decoupling model is as follows: Figure 3 As shown, the online update and early warning logic is as follows: Figure 4 As shown Example 2:

[0042] This embodiment uses a sloped gravity energy storage system as an example. The difference from Embodiment 1 lies in the calculation method of the gravitational component torque in step S4; the other steps are the same.

[0043] For a ramp-type lifting system, the formula for calculating the gravitational component torque is:

[0044] in, The slope angle is [value]. Example 3:

[0045] This embodiment uses a vertical shaft gravity energy storage system as an example. The difference from Embodiment 1 is that the friction component of the sealing components in the transmission system is more significant, and this needs to be considered in the multi-source friction decoupling model in step S5. The component refers to the friction of the seal.

[0046] The separation methods for each component are as follows: Using the no-load calibration results from step S3, separate the speed-related bearing friction component and seal friction component; using measured data from different load stages, fit the wire rope-pulley friction component (positively correlated with load) and the guide rail-guide wheel friction component (related to off-center load) using the least squares method; and attribute the remaining part to the seal friction component.

[0047] Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-mentioned technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by substituting the above-mentioned features with technical features disclosed in this application (but not limited to) that have similar functions.

Claims

1. A method for identifying frictional losses in gravity-based energy storage based on motor electrical signals, characterized in that, Includes the following steps: S1: Signal Acquisition and Preprocessing: Real-time acquisition of the three-phase current of the permanent magnet synchronous motor. and rotational speed Calculate the q-axis current and electromagnetic torque; S2: Calculation of electromagnetic torque and total load torque: Solving for real-time total load torque based on the motor motion equation; S3: No-load friction calibration: With no load attached, run the lifting mechanism at different speeds and record the total load torque. Since the gravitational component of the heavy object is zero, this torque comes from the no-load frictional torque of the transmission system. Establish the relationship curve between no-load friction torque and speed. ; S4: Extraction of total frictional torque during load operation: Total load torque during normal operation with a loaded load. Including the gravitational component torque, the total frictional torque of the transmission system, and the acceleration torque, the total frictional torque of the transmission system is calculated by subtracting the gravitational component torque and the acceleration torque from the total load torque based on this relationship. ; S5: Multi-source friction loss decoupling: The lifting process of heavy objects is divided into multiple intervals according to the load size. Taking advantage of the different contribution ratios of each friction pair under different loads, a multi-source friction decoupling model is established. S6: Online Update and Trend Monitoring: Updates the model parameters of each friction component online, outputs the current value and rate of change of each friction loss component, and issues an early warning when a component exceeds a preset threshold.

2. The method according to claim 1, characterized in that, In step S1, the electromagnetic torque calculation formula is as follows: in, This represents the number of pole pairs of the motor. It is a permanent magnet flux linkage.

3. The method according to claim 1, characterized in that, In step S2, the formula for calculating the real-time total load torque is: in, The total moment of inertia of the system. The coefficient of viscous friction of the motor.

4. The method according to claim 1, characterized in that, In step S4, the formula for calculating the gravitational component torque is: For vertical lifting, according to the formula Calculate, where, For the mass of the heavy object, Where is the radius of the drum. The reduction ratio, For transmission efficiency; For ramp-type lifting systems, according to the formula Calculate, where, The slope angle is [value].

5. The method according to claim 1, characterized in that, In step S4, the method for extracting the total frictional torque is performed during the uniform speed operation segment, at which time the acceleration term... The calculation formula is: 。 6. The method according to claim 1, characterized in that, In step S5, the total frictional torque is decomposed into: in: The bending and friction components of the wire rope with the pulley are directly proportional to the tension of the wire rope. The friction component between the guide rail and the guide wheel is related to the normal force of the guide wheel; The friction component of the winch and pulley bearings is related to the rotational speed. The velocity-related components are separated using the no-load calibration results from step S3. The coefficients of each component are fitted using the least squares method with measured data from different load stages.

7. The method according to claim 1, characterized in that, In step S6, the friction model parameters are updated online using recursive least squares or Kalman filtering algorithms to adapt to changes in lubrication status and wear degree.

8. An online identification system for friction loss in a gravity energy storage transmission system based on electrical signals of a permanent magnet synchronous motor, characterized in that, include: The signal acquisition module is used to acquire the three-phase current, speed, and position or speed of the load of the permanent magnet synchronous motor. The electromagnetic torque calculation module is used to calculate the real-time electromagnetic torque based on the q-axis current. The load torque calculation module is used to calculate the total load torque based on the motor motion equation; The friction calibration module is used to perform no-load calibration and extract total friction force under load conditions. A multi-source friction decoupling module is used to decompose the total friction torque into multiple independent loss components; An online update module is used to dynamically correct model parameters; The output and early warning module is used to display each friction loss component and provide threshold alarms.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method of any one of claims 1-7.

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