A digital twin modeling method and system for the starting process of high-voltage and high-power induction motors

Abstract

The present invention relates to a digital twin modeling method and system for the starting process of a high-voltage and high-power induction motor. The present invention performs real-time compensation based on the deviation between the measured value and the simulated value of the state variable, and adopts a variable step-size efficient simulation strategy, aiming to solve the problems of state detection and real-time control during the starting process of a high-voltage and high-power induction motor, and better detect and control the motor starting process.

Description

Technical Field

[0001] The present invention relates to the field of digital twin modeling of induction motors, and in particular to a digital twin modeling method and system for a starting process of a high-voltage and high-power induction motor. Background Art

[0002] Digital twin (DT) technology realizes monitoring, simulation, optimization and other application requirements of physical entities through interactive mapping of digital virtual entities and modeling in virtual space. It can even perceive the operation status of the power grid in advance in super real time, provide control strategy guidance and fault warning, and has fidelity, scalability and operability. With the help of DT technology to generate a virtual image with full digital elements, it is convenient to simplify the complex energy information and coupling relationship of the physical power grid into a disassembled, simulated and computable mathematical relationship. On the one hand, it can realize the visualization of the operation status of the physical power grid, and on the other hand, it can optimize the deduction results of related activities from multiple angles and levels. Through mutual reference between models, the virtual and real iteration is gradually completed, so as to achieve the ultimate goal of in-depth mining of digital information, building an industrial ecological model and optimizing the management of the physical power grid. The application of digital twin technology relies largely on the support of data calculation, communication capabilities and efficient algorithms. For the starting transient process of important dynamic loads of the power system such as induction motors, due to the short process and large starting current, the algorithm performance and data transmission accuracy are more stringent. Therefore, DT technology is still rarely used for state detection.

[0003] In order to achieve precise control of the starting process of high-voltage and high-power induction motors, health status assessment of induction motors, motor operation status prediction and full life cycle management, it is necessary to use DT technology to establish an induction motor digital twin model and a suitable data interaction algorithm to achieve efficient and highly reliable computational deduction of induction motors, and use the real-time collected operation data to achieve automatic evolution and update of the induction motor digital twin. At the same time, it is necessary to develop a modeling system adapted to the above digital twin model to meet modeling needs. Summary of the invention

[0004] In view of the defects existing in the prior art, the purpose of the present invention is to provide a digital twin modeling method for the starting process of a high-voltage and high-power induction motor. The present invention performs real-time compensation based on the deviation between the measured value and the simulated value of the state variable, and adopts a variable step-size efficient simulation strategy, aiming to solve the problems of state detection and real-time control during the starting process of a high-voltage and high-power induction motor, and better detect and control the motor starting process.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A digital twin modeling method for a high-voltage and high-power induction motor starting process, characterized in that it comprises the following steps:

[0007] Step 1: Get the motor stator current Stator voltage and speed

[0008] Step 2: Use the following formula (1) to detect abnormal data using the 3σ criterion in each power frequency cycle, and delete the data that do not meet the formula (1). In the formula, represents the kth stator current, stator voltage or speed measurement value of the motor obtained in step 1; σ X Indicates the standard deviation of current, voltage or speed in one power frequency cycle; Represents the average value of the stator current, stator voltage or speed obtained in step 1:

[0009]

[0010] Step 3, converting the motor stator current and stator voltage obtained in step 2 after removing bad data into the αβ coordinate system, and using the rotor flux voltage model to calculate the rotor flux estimation value, and simulating the above rotor flux estimation value and the stator current and speed obtained in step 2;

[0011] Step 4: The difference between the measured and simulated state variables X * -X compensation realizes real-time correction of state variables in the subsequent simulation process;

[0012] Step 5: A variable step-size simulation strategy is adopted based on the difference between the actual measurement and the simulation. When the difference is small, a large simulation step-size is automatically adopted; when the difference is large, a small simulation step-size is automatically adopted. Finally, a digital twin model suitable for high-voltage and high-power induction motors is obtained.

[0013] Based on the above scheme, the real-time correction method of the state variable in step 4 is: average the difference between the measured and simulated currents to X k+1 To X k+T , as shown in the following formula (2):

[0014]

[0015] Based on the above scheme, the motor stator current after real-time correction is used Estimated rotor flux The electromagnetic torque during the motor starting process is obtained, as shown in formula (3). And the key physical quantities such as starting torque and starting current are detected and controlled in real time:

[0016]

[0017] Based on the above scheme, the variable step size simulation strategy described in step 5 is specifically as follows:

[0018] According to formula (4), the maximum deviation L of the motor stator current, rotor flux estimation value and speed is calculated, and the calculation step multiple T is determined according to L, as shown in formula (5). The simulation step length can be obtained by formula (6); in formula (6), dt1 is the sensor measurement step length, and dt2 is the simulation step length:

[0019]

[0020]

[0021]

[0022] Based on the above scheme, the digital twin model can take into account the harmonic components. The relevant equations taking into account the harmonic components include the voltage equation (7), the flux equation (8) and the rotor motion equation (9). The electromagnetic torque is calculated by equation (10). The model is established in a k-fold synchronous speed rotating coordinate system:

[0023]

[0024]

[0025]

[0026]

[0027] Another object of the present invention is to provide a modeling system that applies the above-mentioned digital twin modeling method.

[0028] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0029] A digital twin modeling system for the starting process of a high-voltage and high-power induction motor is characterized by comprising: an interconnected data acquisition and processing module, a twin simulation module and a motor starting state evaluation module.

[0030] On the basis of the above scheme:

[0031] The induction motor is powered by an infinite power grid, the machine end of the induction motor is connected to a voltage sensor and a current sensor, and the induction motor is connected to a speed sensor; the data acquisition and processing module is connected to the above-mentioned voltage sensor, current sensor, and speed sensor, and performs data acquisition and transmission; the data acquisition and processing module is connected to the twin simulation module, and performs data exchange; the twin simulation module is connected to the motor starting state evaluation module, and performs data transmission.

[0032] On the basis of the above scheme:

[0033] The data acquisition module includes a data acquisition unit and a data processing unit 1;

[0034] The data acquisition unit is used to collect stator voltage, stator current and speed data from the induction motor, identify data mutations caused by factors such as short-term electromagnetic interference, and make corrections;

[0035] The data processing unit 1 is used to calculate the rotor flux observation value using the voltage and current measurement values ​​obtained by the data acquisition unit, and input the data into the twin simulation module.

[0036] On the basis of the above scheme:

[0037] The twin simulation module includes a data simulation unit and a data processing unit 2;

[0038] The data simulation unit is used for virtual digital simulation of the induction motor starting process, and performs real-time correction of the state variable according to the difference between the measured physical quantity and the simulated state variable;

[0039] The data processing unit 2 is used to output physical quantities such as stator current and rotation speed corrected by the data simulation unit, and transmit them to the motor starting state evaluation module.

[0040] On the basis of the above scheme:

[0041] The motor starting state evaluation module includes a data evaluation unit and a control unit;

[0042] The data evaluation unit is used to judge whether the starting torque, starting current and other indicators are met according to the physical quantities obtained by simulation;

[0043] The control unit is used for performing online control of the induction motor according to the evaluation result of the data evaluation unit.

[0044] The digital twin modeling method and system for the starting process of a high-voltage and high-power induction motor described in the present invention have the following beneficial effects:

[0045] 1) In order to improve the accuracy of the digital twin model, the present invention inputs the deviation between the measured value and the simulated value of the state variable into the twin simulation module and performs real-time compensation, which can make the virtual simulation model more consistent with the actual operating conditions of the induction motor.

[0046] 2) The present invention takes into account the actual needs of the real-time interactive characteristics of the digital twin model for efficient simulation, and proposes a quantized variable-step simulation strategy based on the maximum deviation of the state variables. When the deviation between the simulation and the actual measurement is small, the simulation step size can be automatically increased to improve the simulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention has the following accompanying drawings:

[0048] Figure 1 A schematic flow chart of the digital twin modeling method for the starting process of a high-voltage and high-power induction motor according to the present invention;

[0049] Figure 2 Schematic diagram of the principle of the variable step-size simulation strategy of the twin simulation module of the present invention;

[0050] Figure 3 A schematic diagram of the framework of the digital twin modeling method for the starting process of a high-voltage and high-power induction motor according to the present invention;

[0051] Figure 4 The electrical structure diagram of the digital twin interaction of the high-voltage and high-power induction motor starting process described in the present invention;

[0052] Figure 5 Stator current curve within one power frequency cycle in the embodiment.

[0053] Figure 6 The rotor flux estimation value within one power frequency cycle in the embodiment.

[0054] Figure 7 Comparison of instantaneous values ​​of stator A phase current between the traditional model and the twin simulation model in the embodiment. DETAILED DESCRIPTION

[0055] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0056] like Figure 3 As shown, a digital twin modeling system for the starting process of a high-voltage and high-power induction motor includes: a data acquisition and processing module, a twin simulation module, and a motor starting state evaluation module;

[0057] The data acquisition and processing module is connected to the induction motor sensor in actual operation and performs data acquisition and transmission; the data acquisition and processing module is connected to the twin simulation module and performs data interaction; the twin simulation module is connected to the motor starting state evaluation module and performs data transmission;

[0058] The data acquisition and processing module is used for:

[0059] 1) Collect stator voltage, stator current, and speed data from the induction motor, identify data mutations caused by short-term electromagnetic interference and other factors, and make corrections;

[0060] 2) Use the measured values ​​of voltage and current to calculate the rotor flux observation value, and input the data into the twin simulation module.

[0061] The twin simulation module is used to:

[0062] 1) Virtual digital simulation of the induction motor starting process, and real-time correction of state variables based on the difference between the measured physical quantity and the simulated state variables;

[0063] 2) Output the corrected stator current, speed and other physical quantities and transmit them to the motor starting status evaluation module.

[0064] The motor starting state evaluation module is used to determine whether key indicators such as starting torque and starting current are met based on the physical quantities obtained by simulation.

[0065] The following combination Figure 1 and Figure 2 The technical solution of the present invention is further described in detail. Figure 1 This is a flow chart of the digital twin modeling method for the starting process of a high-voltage and high-power induction motor, which mainly includes the following steps:

[0066] S1, data acquisition and processing module obtains the three-phase starting current of the motor through the sensor Stator voltage and speed

[0067] S2. Using formula (1), use the 3σ criterion to detect abnormal data in each power frequency cycle and delete those that do not meet formula (1).

[0068]

[0069] In the formula, represents the kth stator voltage, current or speed measurement value; σ X Indicates the standard deviation of current, voltage or speed in one power frequency cycle; Indicates the average value of measured current, voltage or speed.

[0070] S3. Convert the measured current and voltage in the three-phase coordinate system to the stationary αβ coordinate system, and use the rotor flux voltage model to calculate the rotor flux estimation value, and input the rotor flux, stator current, and speed data into the twin simulation module.

[0071] S4, when the twin simulation module is running, the difference between the measured and simulated state variables X * -X offset to X k+1 To X k+T , as shown in formula (2), the real-time correction of state variables is realized.

[0072]

[0073] Figure 2 Schematic diagram of the principle of the variable step simulation strategy of the twin simulation module, the specific steps include:

[0074] The twin digital model interacts with the actual motor once at each measurement step of the sensor, and the maximum deviation L of the stator current, rotor flux and speed is calculated according to formula (3), and the calculation step multiple T is determined according to L, as shown in formula (4). The simulation step of the twin digital model is determined by T, as shown in formula (5).

[0075]

[0076]

[0077]

[0078] Example

[0079] The application effect of the present invention is described below with reference to an example. Taking a 37kW induction motor as an example, the digital twin model is used to monitor the full-voltage starting process in real time, and the motor parameters are shown in Table 1.

[0080] Table 1 Motor parameters

[0081]

[0082] Step 1: Get the motor stator current within one cycle Stator voltage and speed

[0083] Step 2: Use the 3σ criterion to detect abnormal data. The following is an example of stator current: Set the initial calculation step length multiple T = 5, dt1 = 0.0001s, dt2 = 0.00002s. In one power frequency cycle, a total of 167 points are collected, such as Figure 4 As shown in the figure, the average value of the stator current is -190.07A and the standard deviation is 428.92. Since each data point satisfies Therefore, there is no bad data. The stator voltage and speed also have no bad data after the above calculation.

[0084] Step 3: Convert the motor stator current and stator voltage obtained in step 2 after removing bad data into the αβ coordinate system, and use the rotor flux voltage model to calculate the rotor flux estimation value, such as Figure 5 The above rotor flux estimation value and the stator current and speed obtained in step 2 are simulated.

[0085] Step 4: Use variable step simulation strategy to determine the simulation step of the twin model. At t = 0.0001s, the first data interaction is performed. The maximum deviation of the state variable L = 0.0065 can be calculated by formula (1), and the next calculation step multiple T = 3 can be obtained by formula (2).

[0086]

[0087]

[0088] Step 5: A digital twin model that can take into account harmonic components is used. The relevant equations include the voltage equation (3), the flux equation (4) and the rotor motion equation (5). The electromagnetic torque is calculated by equation (6). The model is established in a k-fold synchronous speed rotating coordinate system.

[0089]

[0090]

[0091]

[0092]

[0093] The following real-time correction method is used to average the difference between the measured and simulated currents to X k+1 To X k+T Taking the stator d-axis current as an example, the calculation step length multiple T=3 is determined by step 4, so the current compensation amount is (I * -I) / T=(0.5368-0.5403) / 3=-0.0012A, which is compensated to I6, I7, and I8, as shown in equation (7). The compensation strategy for rotor flux and speed is the same as that for current.

[0094]

[0095] The above twin simulation model and state variable real-time correction strategy are used to simulate the next step until the entire motor starting process is completed. The calculation results are as follows: Figure 6 shown.

[0096] Figure 6The measured and simulated comparison of the instantaneous value of the stator A phase current is shown, in which the simulation values ​​are obtained using the traditional model and the digital twin model respectively. It can be seen that the calculation results of the present invention are closer to the measured values ​​than the traditional induction motor model. This is because during the operation of the motor, the induction motor has magnetic circuit saturation, which causes the inductance parameter to be nonlinear and time-varying, and the traditional model cannot take the above factors into account, so the deviation from the measured current is large. Using the twin interaction compensation method proposed in the present invention, the deviation between the simulation and the measured current is small, indicating that the present invention can accurately simulate the dynamic behavior of the actual motor. In summary, the digital twin modeling method of the starting process of the high-voltage and high-power induction motor described in the present invention makes full use of the deviation between the simulation model and the actual motor state variables to compensate the model in real time, which can make the simulation model close to the actual motor operation state. At the same time, the variable step size simulation strategy based on the state variable deviation value proposed in the present invention can effectively improve the simulation efficiency and meet the real-time requirements for online control.

[0097] Those skilled in the art will appreciate that various modifications and variations may be made to the present invention without departing from the spirit and scope of the present invention. Therefore, if any modification or variation falls within the scope of protection of the appended claims and equivalents, it is considered that the present invention covers these modifications and variations.

[0098] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A digital twin modeling method for the starting process of a high-voltage and high-power induction motor, characterized in that: The steps include: Step 1: Get the motor stator current Stator voltage and speed Step 2: Use the following formula (1) to detect abnormal data using the 3σ criterion in each power frequency cycle, and delete the data that do not meet the formula (1). In the formula, represents the kth stator current, stator voltage or speed measurement value of the motor obtained in step 1; σ X Indicates the standard deviation of current, voltage or speed in one power frequency cycle; Represents the average value of the stator current, stator voltage or speed obtained in step 1: Step 3, converting the motor stator current and stator voltage obtained in step 2 after removing bad data into the αβ coordinate system, and using the rotor flux voltage model to calculate the rotor flux estimation value, and simulating the above rotor flux estimation value and the stator current and speed obtained in step 2; Step 4: The difference between the measured and simulated state variables X * -X compensation realizes real-time correction of state variables in the subsequent simulation process; Step 5: A variable step-size simulation strategy is adopted based on the difference between the actual measurement and the simulation. When the difference is small, a large simulation step-size is automatically adopted; when the difference is large, a small simulation step-size is automatically adopted. Finally, a digital twin model suitable for high-voltage and high-power induction motors is obtained.

2. A digital twin modeling method for a high-voltage and high-power induction motor starting process as claimed in claim 1, characterized in that: The real-time correction method of the state variable in step 4 is: average the difference between the measured and simulated currents to X k+1 To X k+T , as shown in the following formula (2): In the above formula, represents the k+ith modified state variable.

3. A digital twin modeling method for a high-voltage and high-power induction motor starting process as claimed in claim 2, characterized in that: Using the real-time corrected motor stator current Estimated rotor flux The electromagnetic torque during the motor starting process is obtained, as shown in formula (3), and the key physical quantities of starting torque and starting current are detected and controlled in real time: In the above formula, is the estimated value of the stator and rotor dq axis flux linkage after real-time correction; is the stator and rotor dq axis current after real-time correction; L rl , L m They are stator and rotor leakage inductance and magnetizing inductance respectively.

4. A digital twin modeling method for a high-voltage and high-power induction motor starting process as claimed in claim 3, characterized in that: The variable step size simulation strategy described in step 5 is specifically as follows: According to formula (4), the maximum deviation L of the motor stator current, rotor flux estimation value and speed is calculated, and the calculation step multiple T is determined according to L, as shown in formula (5). The simulation step length can be obtained by formula (6); in formula (6), dt1 is the sensor measurement step length, and dt2 is the simulation step length:

5. A digital twin modeling method for a high-voltage and high-power induction motor starting process as claimed in claim 4, characterized in that: The digital twin model can take into account the harmonic components. The relevant equations taking into account the harmonic components include the voltage equation (7), the flux equation (8) and the rotor motion equation (9). The electromagnetic torque is calculated by equation (10). The model is established in a k-fold synchronous speed rotating coordinate system: In the above formulas, k is the harmonic order; ω B is the fundamental electrical angular velocity, U ds , U qs , U dr , U qr is the stator and rotor dq axis voltage; for squirrel cage induction motor, U dr =U qr =0; R s , R r is the stator and rotor resistance; ds ,Ψ qs ,Ψ dr ,Ψ qr is the stator and rotor dq axis flux; I ds ,I qs ,I dr ,I qr is the stator and rotor dq axis current; ω r is the rotor electrical angular velocity; p is the differential operator; L sl , L rl , L m They are stator and rotor leakage inductance and excitation inductance respectively, divided by time t and electrical angular velocity ω B Except for the nominal values, all other quantities are expressed in per unit values.

6. A modeling system using the method of claim 1, characterized in that: include: Interconnected data acquisition and processing module, twin simulation module and motor starting state evaluation module; The induction motor is powered by an infinite power grid, the machine end of the induction motor is connected to a voltage sensor and a current sensor, and the induction motor is connected to a speed sensor; the data acquisition and processing module is connected to the above-mentioned voltage sensor, current sensor, and speed sensor, and performs data acquisition and transmission; the data acquisition and processing module is connected to the twin simulation module, and performs data exchange; the twin simulation module is connected to the motor starting state evaluation module, and performs data transmission.

7. A modeling system as claimed in claim 6, characterized in that: The data acquisition module includes a data acquisition unit and a data processing unit 1; The data acquisition unit is used to collect stator voltage, stator current and speed data from the induction motor, identify data mutations caused by short-term electromagnetic interference factors, and make corrections; The data processing unit 1 is used to calculate the rotor flux observation value using the voltage and current measurement values ​​obtained by the data acquisition unit, and input the data into the twin simulation module.

8. A modeling system as claimed in claim 6, characterized in that: The twin simulation module includes a data simulation unit and a data processing unit 2; The data simulation unit is used for virtual digital simulation of the induction motor starting process, and performs real-time correction of the state variable according to the difference between the measured physical quantity and the simulated state variable; The data processing unit 2 is used to output the stator current and speed physical quantities corrected by the data simulation unit and transmit them to the motor starting state evaluation module.

9. A modeling system as claimed in claim 6, characterized in that: The motor starting state evaluation module includes a data evaluation unit and a control unit; The data evaluation unit is used to judge whether the starting torque and starting current indicators are met according to the physical quantities obtained by simulation; The control unit is used for performing online control of the induction motor according to the evaluation result of the data evaluation unit.

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