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Volume 51,Issue 7,2024 Table of Contents
2024, 51(7):1-9.
DOI: 10.12177/emca.2024.063
Abstract:
Six-phase permanent magnet synchronous generator (PMSG) has broad application prospects due to its low harmonic content, mature decoupling methods, and strong stability. To improve the dynamic performance of the six-phase PMSG when the load torque suddenly changes, and to enhance the system’s anti-interference ability, a feedforward compensation strategy using the load torque observation value is proposed. Firstly, the load torque is observed by the sliding-mode observer, the sliding surface of the observer is designed as the difference between the actual speed and the observed speed, and the chattering signal can be filtered out during the observation process without causing phase and amplitude changes. Secondly, the load torque observation value is proportionally feed forward to the given value of the current loop, making up for the problem of insufficient amplitude of the discontinuity term of the sliding mode controller. Thirdly, for the problem that the feedforward proportion constant is too large, resulting in the speed not being able to quickly stabilized at the given value, the feedforward proportion coefficient is set to a variable value, which effectively suppresses the speed fluctuation. Finally, based on Matlab/Simulink, the simulation model of multi-phase-modular multilevel converter (MP-MMC) drive six-phase PMSG load torque observation feedforward sliding-mode control is established to validate the proposed stratage. The simulation results show that the sliding-mode observer can accurately observe the load torque, and the feedforward compensation strategy effectively suppresses the speed fluctuation caused by the sudden load change.
Six-phase permanent magnet synchronous generator (PMSG) has broad application prospects due to its low harmonic content, mature decoupling methods, and strong stability. To improve the dynamic performance of the six-phase PMSG when the load torque suddenly changes, and to enhance the system’s anti-interference ability, a feedforward compensation strategy using the load torque observation value is proposed. Firstly, the load torque is observed by the sliding-mode observer, the sliding surface of the observer is designed as the difference between the actual speed and the observed speed, and the chattering signal can be filtered out during the observation process without causing phase and amplitude changes. Secondly, the load torque observation value is proportionally feed forward to the given value of the current loop, making up for the problem of insufficient amplitude of the discontinuity term of the sliding mode controller. Thirdly, for the problem that the feedforward proportion constant is too large, resulting in the speed not being able to quickly stabilized at the given value, the feedforward proportion coefficient is set to a variable value, which effectively suppresses the speed fluctuation. Finally, based on Matlab/Simulink, the simulation model of multi-phase-modular multilevel converter (MP-MMC) drive six-phase PMSG load torque observation feedforward sliding-mode control is established to validate the proposed stratage. The simulation results show that the sliding-mode observer can accurately observe the load torque, and the feedforward compensation strategy effectively suppresses the speed fluctuation caused by the sudden load change.
2024, 51(7):10-20.
DOI: 10.12177/emca.2024.066
Abstract:
Under the frequent peaking operation of water-hydrogen-hydrogen cooled turbo-generator, the temperature of the rotor winding changes repeatedly for a long time and is subjected to thermal stress, which leads to deformation of winding and inter-turn insulation, and directly affects the performance and stability of the generator, so it is very important to study the temperature distribution law and the thermal deformation law of the rotor winding under the variable operating conditions. A 600 MW water-hydrogen-hydrogen cooled turbo-generator is taken as the object of study, according to the rotor structure, the calculation area under the rotating state is determined, and a three-dimensional electric-heat-fluid coupling calculation model is established. Under the corresponding basic assumptions and boundary conditions, the temperature field and fluid field distribution of the rotor are calculated, and the accuracy of the simulation calculations is verified by comparing the measured results. The results of the rotor temperature field are taken as thermal loads, and the corresponding boundary conditions are added to calculate the thermal deformation of the rotor winding under variable operating conditions, and the thermal deformation law is further summarized.
Under the frequent peaking operation of water-hydrogen-hydrogen cooled turbo-generator, the temperature of the rotor winding changes repeatedly for a long time and is subjected to thermal stress, which leads to deformation of winding and inter-turn insulation, and directly affects the performance and stability of the generator, so it is very important to study the temperature distribution law and the thermal deformation law of the rotor winding under the variable operating conditions. A 600 MW water-hydrogen-hydrogen cooled turbo-generator is taken as the object of study, according to the rotor structure, the calculation area under the rotating state is determined, and a three-dimensional electric-heat-fluid coupling calculation model is established. Under the corresponding basic assumptions and boundary conditions, the temperature field and fluid field distribution of the rotor are calculated, and the accuracy of the simulation calculations is verified by comparing the measured results. The results of the rotor temperature field are taken as thermal loads, and the corresponding boundary conditions are added to calculate the thermal deformation of the rotor winding under variable operating conditions, and the thermal deformation law is further summarized.
2024, 51(7):21-32.
DOI: 10.12177/emca.2024.061
Abstract:
The model predictive current control (MPCC) strategy for permanent magnet synchronous motor has been widely used because of its good dynamic performance, but the strategy is more dependent on the accuracy of model parameters. In order to improve the parameter robustness of the system while maintaining the dynamic performance of the control system, a three-vector based incremental MPCC strategy is proposed. A model reference adaptive inductance identification algorithm based on d axis current is introduced in MPCC, and the adaptive law is analyzed. Simulations based on Matlab/Simulink are carried out, the results show that the proposed strategy can achieve the reduction of the prediction error caused by the mismatch of flux linkage parameters while maintaining the dynamic performance of the three-vector predictive control. In addition, the model reference adaptive algorithm based on d axis current can perform fast and stable inductor parameter identification, which effectively improves the parameter robustness of the control system.
The model predictive current control (MPCC) strategy for permanent magnet synchronous motor has been widely used because of its good dynamic performance, but the strategy is more dependent on the accuracy of model parameters. In order to improve the parameter robustness of the system while maintaining the dynamic performance of the control system, a three-vector based incremental MPCC strategy is proposed. A model reference adaptive inductance identification algorithm based on d axis current is introduced in MPCC, and the adaptive law is analyzed. Simulations based on Matlab/Simulink are carried out, the results show that the proposed strategy can achieve the reduction of the prediction error caused by the mismatch of flux linkage parameters while maintaining the dynamic performance of the three-vector predictive control. In addition, the model reference adaptive algorithm based on d axis current can perform fast and stable inductor parameter identification, which effectively improves the parameter robustness of the control system.
2024, 51(7):33-42.
DOI: 10.12177/emca.2024.058
Abstract:
Aiming at the problem of large common-mode voltage in model predictive torque control of permanent magnet synchronous motor, the common-mode voltage suppression effectiveness of three methods, namely, joint control of flux linkage, torque and common mode voltage, direct removal of zero voltage vector and virtual zero voltage vector, is analyzed comparatively. Simulation results show that all three methods can effectively suppress the common-mode voltage. The first two methods do not use zero voltage vector, resulting in increased flux linkage ripple and torque ripple. Virtual zero voltage vector method retains the zero voltage vector and effectively suppresses the common-mode voltage, but the switching frequency increases. Adaptive dynamic virtual zero voltage vector method selects the zero voltage vector generation method with the smallest number of switching times, which can effectively reduce the switching frequency under the premise of the basically equivalent control performance, with the optimal overall performance.
Aiming at the problem of large common-mode voltage in model predictive torque control of permanent magnet synchronous motor, the common-mode voltage suppression effectiveness of three methods, namely, joint control of flux linkage, torque and common mode voltage, direct removal of zero voltage vector and virtual zero voltage vector, is analyzed comparatively. Simulation results show that all three methods can effectively suppress the common-mode voltage. The first two methods do not use zero voltage vector, resulting in increased flux linkage ripple and torque ripple. Virtual zero voltage vector method retains the zero voltage vector and effectively suppresses the common-mode voltage, but the switching frequency increases. Adaptive dynamic virtual zero voltage vector method selects the zero voltage vector generation method with the smallest number of switching times, which can effectively reduce the switching frequency under the premise of the basically equivalent control performance, with the optimal overall performance.
2024, 51(7):43-52.
DOI: 10.12177/emca.2024.055
Abstract:
Based on the average value model, the capacitor repetitive charging system of pulsed homopolar inductor alternator is studied. The variation law of sub-transient flux linkage during the charging process is analyzed, as well as the impact of sub-transient flux linkage variation on charging performance. Simulation and calculation results show that the sub-transient flux linkage gradually decrease during the charging process. When the charging time is equivalent to the electromagnetic time constant of the generator, the decrease in the sub-transient flux linkage during the charging process leads to a significant decrease in the charging voltage, so the impact of the sub-transient flux linkage change must be considered. The impact of excitation power supply with constant current control function on the regulation during charging is further studied, and it is pointed out that in order to reduce the insulation requirements of the generator, a gradual rise of the excitation current in the repetitive charging and discharging pulse mode should be adopted.
Based on the average value model, the capacitor repetitive charging system of pulsed homopolar inductor alternator is studied. The variation law of sub-transient flux linkage during the charging process is analyzed, as well as the impact of sub-transient flux linkage variation on charging performance. Simulation and calculation results show that the sub-transient flux linkage gradually decrease during the charging process. When the charging time is equivalent to the electromagnetic time constant of the generator, the decrease in the sub-transient flux linkage during the charging process leads to a significant decrease in the charging voltage, so the impact of the sub-transient flux linkage change must be considered. The impact of excitation power supply with constant current control function on the regulation during charging is further studied, and it is pointed out that in order to reduce the insulation requirements of the generator, a gradual rise of the excitation current in the repetitive charging and discharging pulse mode should be adopted.
2024, 51(7):53-63.
DOI: 10.12177/emca.2024.065
Abstract:
In order to solve the problem of low power factor of vernier motor, a motor design optimization concept to improve the power factor is proposed. Firstly, the winding function approach is used to calculate the inductance of fractional slot centralized double-layer windings, to derive the expression for the power factor of the vernier motor, and to analyze the main design parameters affecting the power factor. Secondly, combined with the finite element method to study the change rule of motor performance when each design parameter is changed, and then summarize the design concept. Then, a cleft tooth vernier motor is taken as the benchmark prototype, a motor with high power factor is redesigned according to the proposed concept, and a genetic algorithm is used for multi-objective optimization of the main design parameters of the motor. Finally, the performance comparison with the benchmark prototype motor shows that the power factor of the designed motor is higher, which verifies the validity of the theoretical analysis and the proposed design concept.
In order to solve the problem of low power factor of vernier motor, a motor design optimization concept to improve the power factor is proposed. Firstly, the winding function approach is used to calculate the inductance of fractional slot centralized double-layer windings, to derive the expression for the power factor of the vernier motor, and to analyze the main design parameters affecting the power factor. Secondly, combined with the finite element method to study the change rule of motor performance when each design parameter is changed, and then summarize the design concept. Then, a cleft tooth vernier motor is taken as the benchmark prototype, a motor with high power factor is redesigned according to the proposed concept, and a genetic algorithm is used for multi-objective optimization of the main design parameters of the motor. Finally, the performance comparison with the benchmark prototype motor shows that the power factor of the designed motor is higher, which verifies the validity of the theoretical analysis and the proposed design concept.
7 Design and Analysis of Permanent Magnet-Reluctance Composite Synchronous Motor for Vacuum Dry Pumps
2024, 51(7):64-73.
DOI: 10.12177/emca.2024.057
Abstract:
Aiming at the problem of difficult rotor heat dissipation in vacuum environment for drive motors for vacuum dry pumps, a hybrid excitation permanent magnet-reluctance composite synchronous motor is designed. The motor rotor permanent magnet excitation structure consists of two types of magnets, NdFeB and ferrite, aiming to change the arrangement of permanent magnets to reduce the loss of the motor. Firstly, the topology of the motor rotor is constructed, and two schemes are designed to study the influence of the arrangement of permanent magnets on the performance of the motor. Secondly, the effect of the rotor parameters on the no-load back electromotive force and electromagnetic torque of the motor is analyzed and the size of the motor rotor is adjusted. Thirdly, the losses of the two schemes are compared, and a low-loss motor scheme is selected. Finally, the temperature field analysis of the target motor is carried out by finite element calculation, and the results show that the motor temperature distribution of the designed scheme is reasonable, so the motor efficiency can be effectively improved by changing the arrangement of the permanent magnets, reducing the motor loss and ensuring the stable operation of the motor.
Aiming at the problem of difficult rotor heat dissipation in vacuum environment for drive motors for vacuum dry pumps, a hybrid excitation permanent magnet-reluctance composite synchronous motor is designed. The motor rotor permanent magnet excitation structure consists of two types of magnets, NdFeB and ferrite, aiming to change the arrangement of permanent magnets to reduce the loss of the motor. Firstly, the topology of the motor rotor is constructed, and two schemes are designed to study the influence of the arrangement of permanent magnets on the performance of the motor. Secondly, the effect of the rotor parameters on the no-load back electromotive force and electromagnetic torque of the motor is analyzed and the size of the motor rotor is adjusted. Thirdly, the losses of the two schemes are compared, and a low-loss motor scheme is selected. Finally, the temperature field analysis of the target motor is carried out by finite element calculation, and the results show that the motor temperature distribution of the designed scheme is reasonable, so the motor efficiency can be effectively improved by changing the arrangement of the permanent magnets, reducing the motor loss and ensuring the stable operation of the motor.
2024, 51(7):74-83.
DOI: 10.12177/emca.2024.064
Abstract:
In mechanical load measurement for large wind turbines, the accuracy of load calibration for edgewise and flatwise bending moments implemented by blade gravity has a direct influence on the testing effectiveness for blade and rotor loads. Therefore, analyzing the bending moment analytic results of the blade gravity at the strain gauge measurement position is the key to blade load calibration. Firstly, using the principle of analytical geometry, an bending moment analytic method for blade gravity is proposed based on optimized three-dimensional coordinate system and coordinate transformation. Secondly, in order to eliminate the influence of the main shaft tilt angle on the optimized three-dimensional coordinate system, a method to adjust the direction of the blade gravity vector in the optimized coordinate system is proposed, and the analytical expressions of blade edgewise moment and flatwise moment are obtained taking into account various influential factors. Finally, in the actual blade load test project, the two calibration analysis methods are applied respectively, and the blade load test results obtained by the two methods have good consistency and representativity. The validity and feasibility of the proposed analytic method for gravity load calibration of blade bending moments are verified by theoretical analysis and testing results.
In mechanical load measurement for large wind turbines, the accuracy of load calibration for edgewise and flatwise bending moments implemented by blade gravity has a direct influence on the testing effectiveness for blade and rotor loads. Therefore, analyzing the bending moment analytic results of the blade gravity at the strain gauge measurement position is the key to blade load calibration. Firstly, using the principle of analytical geometry, an bending moment analytic method for blade gravity is proposed based on optimized three-dimensional coordinate system and coordinate transformation. Secondly, in order to eliminate the influence of the main shaft tilt angle on the optimized three-dimensional coordinate system, a method to adjust the direction of the blade gravity vector in the optimized coordinate system is proposed, and the analytical expressions of blade edgewise moment and flatwise moment are obtained taking into account various influential factors. Finally, in the actual blade load test project, the two calibration analysis methods are applied respectively, and the blade load test results obtained by the two methods have good consistency and representativity. The validity and feasibility of the proposed analytic method for gravity load calibration of blade bending moments are verified by theoretical analysis and testing results.
2024, 51(7):84-93.
DOI: 10.12177/emca.2024.053
Abstract:
With the high proportion of new energy units integrated into the power grid, the low inertia characteristic of the power system become more and more significant, which seriously affects the stability of the system operation. In order to accurately estimate the inertia of new energy power grid in actual operation state, a new energy power system equivalent inertia estimation method based on weighted recursive least squares (WRLS) -auto-regressive moving average exogenous(ARMAX) system identification is proposed. Firstly, a general inertia analytical model of generator power-frequency response characteristics under different disturbance conditions is established with the generator as the object. Secondly, the ARMAX model is established by taking the generator grid-connected bus active power and frequency disturbances as inputs and outputs. Considering that the actual power grid operation process is jointly affected by both large and small perturbations, the actual measurement data is heteroscedasticity, and the to-be-identified parameters in the model are solved by WRLS. Then, the transfer function model containing the inertia response in the identification model is extracted, and the inertia time constant of the inertia source is calculated using the step response, and the equivalent inertia of the system is calculated. Finally, the accuracy and practicability of the proposed method are verified by Matlab/Simulink simulation examples.
With the high proportion of new energy units integrated into the power grid, the low inertia characteristic of the power system become more and more significant, which seriously affects the stability of the system operation. In order to accurately estimate the inertia of new energy power grid in actual operation state, a new energy power system equivalent inertia estimation method based on weighted recursive least squares (WRLS) -auto-regressive moving average exogenous(ARMAX) system identification is proposed. Firstly, a general inertia analytical model of generator power-frequency response characteristics under different disturbance conditions is established with the generator as the object. Secondly, the ARMAX model is established by taking the generator grid-connected bus active power and frequency disturbances as inputs and outputs. Considering that the actual power grid operation process is jointly affected by both large and small perturbations, the actual measurement data is heteroscedasticity, and the to-be-identified parameters in the model are solved by WRLS. Then, the transfer function model containing the inertia response in the identification model is extracted, and the inertia time constant of the inertia source is calculated using the step response, and the equivalent inertia of the system is calculated. Finally, the accuracy and practicability of the proposed method are verified by Matlab/Simulink simulation examples.
2024, 51(7):94-102.
DOI: 10.12177/emca.2024.062
Abstract:
In response to the difficulty and time-consuming problem of tuning the parameters of the current inner loop and speed outer loop proportional integral (PI) controller in field oriented control, a parameter self-tuning model for a permanent magnet vernier motor magnetic field orientation control dual closed-loop speed regulation system is constructed based on the field oriented control autotuner (FOCA) module in Matlab/Simulink. This module injects a sinusoidal disturbance signal into the output of the PI controller, calculates the frequency response based on the system input and output data, automatically adjusts the PI parameters based on the frequency response, and achieves the specified target bandwidth and phase margin. Finally, the control performance of each loop before and after tuning are analyzed and compared by simulation, and the simulation results show that using the FOCA module can quickly and automatically adjust the PI controller parameters and has good control performance.
In response to the difficulty and time-consuming problem of tuning the parameters of the current inner loop and speed outer loop proportional integral (PI) controller in field oriented control, a parameter self-tuning model for a permanent magnet vernier motor magnetic field orientation control dual closed-loop speed regulation system is constructed based on the field oriented control autotuner (FOCA) module in Matlab/Simulink. This module injects a sinusoidal disturbance signal into the output of the PI controller, calculates the frequency response based on the system input and output data, automatically adjusts the PI parameters based on the frequency response, and achieves the specified target bandwidth and phase margin. Finally, the control performance of each loop before and after tuning are analyzed and compared by simulation, and the simulation results show that using the FOCA module can quickly and automatically adjust the PI controller parameters and has good control performance.
11 Fault Diagnosis Model of VSC-STATCOM Inverter Based on Dual-Mode Decomposition Multi-Channel Input
KONG Fanwen
,
BI Guihong
,
ZHAO Sihong
,
WANG Xiangwei
,
CHEN Dongjing
,
ZHANG Jingchao
,
CHEN Shilong
2024, 51(7):103-118.
DOI: 10.12177/emca.2024.054
Abstract:
Aiming at the problems of insufficient signal feature extraction, insufficient recognition ability of deep learning network and low recognition rate under high noise condition in inverter fault diagnosis in traditional voltage source converter static synchronous compensator, an inverter fault diagnosis method based on the combination of dual-mode decomposition, multi-channel input(MCI), parallel convolutional neural network(PCNN), bi-directional long and short-term memory (BiLSTM) neural network and self-attention(SA) mechanism is proposed. Firstly, the three-phase current output of the inverter is decomposed by variational mode decomposition and time-varying filter empirical mode decomposition, which reduces the complexity of the original signal and realizes the law complementation between different modal components. Secondly, MCI-PCNN-BiLSTM-SA combined model is used to extract, learn and recognize the feature matrix. Finally, the proposed method is validated by simulation, and the results show that the proposed method has strong feature extraction ability, with an average recognition rate of 99.48% in the case of no noise and 95.59% in the case of high noise.
Aiming at the problems of insufficient signal feature extraction, insufficient recognition ability of deep learning network and low recognition rate under high noise condition in inverter fault diagnosis in traditional voltage source converter static synchronous compensator, an inverter fault diagnosis method based on the combination of dual-mode decomposition, multi-channel input(MCI), parallel convolutional neural network(PCNN), bi-directional long and short-term memory (BiLSTM) neural network and self-attention(SA) mechanism is proposed. Firstly, the three-phase current output of the inverter is decomposed by variational mode decomposition and time-varying filter empirical mode decomposition, which reduces the complexity of the original signal and realizes the law complementation between different modal components. Secondly, MCI-PCNN-BiLSTM-SA combined model is used to extract, learn and recognize the feature matrix. Finally, the proposed method is validated by simulation, and the results show that the proposed method has strong feature extraction ability, with an average recognition rate of 99.48% in the case of no noise and 95.59% in the case of high noise.
2024, 51(7):119-131.
DOI: 10.12177/emca.2024.059
Abstract:
Sub-synchronous oscillations induced by the interaction between direct-drive wind turbines and the grid pose a serious threat to the safe and stable operation of the power grid. To rapidly identify the triggering unit, a localization method for sub-synchronous oscillation source based on short-time Fourier transform (STFT) images and transfer learning is proposed. Firstly, compressive sensing technology is employed to transform output data into observation signals, and then the STFT is performed on the observation signals to obtain the mapping image with oscillation characteristics, and the link between the mapping image and the oscillation source unit is constructed. Secondly, an adversarial transfer learning architecture is utilized in conjunction with the power system to achieve rapid generalization of unlabeled oscillation data in the target domain. Finally, the traditional transfer learning method is introduced for comparison, the results show that the proposed method performs better in terms of localization accuracy and efficiency, and has strong noise resistance.
Sub-synchronous oscillations induced by the interaction between direct-drive wind turbines and the grid pose a serious threat to the safe and stable operation of the power grid. To rapidly identify the triggering unit, a localization method for sub-synchronous oscillation source based on short-time Fourier transform (STFT) images and transfer learning is proposed. Firstly, compressive sensing technology is employed to transform output data into observation signals, and then the STFT is performed on the observation signals to obtain the mapping image with oscillation characteristics, and the link between the mapping image and the oscillation source unit is constructed. Secondly, an adversarial transfer learning architecture is utilized in conjunction with the power system to achieve rapid generalization of unlabeled oscillation data in the target domain. Finally, the traditional transfer learning method is introduced for comparison, the results show that the proposed method performs better in terms of localization accuracy and efficiency, and has strong noise resistance.
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Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
沪ICP备16038578号-3
Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
