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Volume 47,Issue 6,2020 Table of Contents
2020, 47(6):1-5.
DOI: 10.12177/emca.2020.033
Abstract:
The inductance of the internal permanent magnet synchronous motor (PMSM) will decrease as the saturation of the magnetic circuit deepens, which results in parameters variation with the running condition varying in the motor control system. Therefore, the accurate identification of inductance parameters has a great influence on the control performance of the motor. To solve this problem, a least squares inductance identification method based on forgetting factor is proposed using the transient voltage equation of PMSM. A simulation model is established, and the results of the identification method are obtained when the speed and torque change. Based on the dSPACE experiment platform, the identification method is verified by experiments. Comparison between simulation and experimental results proves that this method has good realtime performance and effectiveness in the control of internal PMSM.
The inductance of the internal permanent magnet synchronous motor (PMSM) will decrease as the saturation of the magnetic circuit deepens, which results in parameters variation with the running condition varying in the motor control system. Therefore, the accurate identification of inductance parameters has a great influence on the control performance of the motor. To solve this problem, a least squares inductance identification method based on forgetting factor is proposed using the transient voltage equation of PMSM. A simulation model is established, and the results of the identification method are obtained when the speed and torque change. Based on the dSPACE experiment platform, the identification method is verified by experiments. Comparison between simulation and experimental results proves that this method has good realtime performance and effectiveness in the control of internal PMSM.
2020, 47(6):6-11.
DOI: 10.12177/emca.2020.019
Abstract:
In the precise linear motor motion platform systems, the nonlinear factors such as model parameter uncertainties and the end effect and positioning force fluctuation caused by the motor structural characteristics may lead to the dynamic response degradation. Aiming at this problem, the mathematical model of the linear motor motion platform is analyzed. A fuzzy active disturbance rejection controller (ADRC) is designed, and models of the servo motion platform and the controller are established using Simulink. Simulation is performed to further optimize the control parameters. The simulation results show that, compared with the traditional PID controller and the classical ADRC, the following error decreases and the anti-interference capability increases significantly, indicating that the fuzzy ADRC has more precise dynamic following ability and better anti-interference capability, robustness and adaptive ability.
In the precise linear motor motion platform systems, the nonlinear factors such as model parameter uncertainties and the end effect and positioning force fluctuation caused by the motor structural characteristics may lead to the dynamic response degradation. Aiming at this problem, the mathematical model of the linear motor motion platform is analyzed. A fuzzy active disturbance rejection controller (ADRC) is designed, and models of the servo motion platform and the controller are established using Simulink. Simulation is performed to further optimize the control parameters. The simulation results show that, compared with the traditional PID controller and the classical ADRC, the following error decreases and the anti-interference capability increases significantly, indicating that the fuzzy ADRC has more precise dynamic following ability and better anti-interference capability, robustness and adaptive ability.
2020, 47(6):12-16.
DOI: 10.12177/emca.2020.023
Abstract:
In order to solve the problem of speed fluctuation and poor dynamic speed regulation characteristic of brushless DC motor (BLDCM) in the low or medium speed status, a control strategy combining advanced fuzzy selftuning PI control and PLC is proposed for BLDCM speed regulation. On the basis of traditional PI controller, the advanced fuzzy PI control strategy integrates the integral reset link with PI controller, which can not only adjust the parameters in real time, but also avoid the problem of integral saturation in the control process. The PLC is programmed by Visual C++. Experiment results prove that, the proposed control strategy has the advantages of fast response, good stability and nonovershoot when the motor is running in the low or medium speed range.
In order to solve the problem of speed fluctuation and poor dynamic speed regulation characteristic of brushless DC motor (BLDCM) in the low or medium speed status, a control strategy combining advanced fuzzy selftuning PI control and PLC is proposed for BLDCM speed regulation. On the basis of traditional PI controller, the advanced fuzzy PI control strategy integrates the integral reset link with PI controller, which can not only adjust the parameters in real time, but also avoid the problem of integral saturation in the control process. The PLC is programmed by Visual C++. Experiment results prove that, the proposed control strategy has the advantages of fast response, good stability and nonovershoot when the motor is running in the low or medium speed range.
2020, 47(6):17-21.
DOI: 10.12177/emca.2020.040
Abstract:
In the sensorless control system of permanent magnet synchronous motors(PMSMs), the high robustness of the sliding mode observer has been a research hotspot. To solve the problems of large amounts of calculation of the traditional sliding mode observer (SMO) and its high-frequency chattering, a new SMO for the medium and high speed sensorless control process of PMSM is designed. The boundary layer and phase-locked loop (PLL) technology are applied in SMO, and the mathematical model of SMO is built. The design of PLL is strictly deduced, and the precision of rotor position is reasonably verified. Finally, the design is implemented by simulation and experiment. The results show that the proposed new SMO has good suppression of high-frequency chattering. Simultaneously, the precision and robustness of the new SMO are higher.
In the sensorless control system of permanent magnet synchronous motors(PMSMs), the high robustness of the sliding mode observer has been a research hotspot. To solve the problems of large amounts of calculation of the traditional sliding mode observer (SMO) and its high-frequency chattering, a new SMO for the medium and high speed sensorless control process of PMSM is designed. The boundary layer and phase-locked loop (PLL) technology are applied in SMO, and the mathematical model of SMO is built. The design of PLL is strictly deduced, and the precision of rotor position is reasonably verified. Finally, the design is implemented by simulation and experiment. The results show that the proposed new SMO has good suppression of high-frequency chattering. Simultaneously, the precision and robustness of the new SMO are higher.
2020, 47(6):22-26.
DOI: 10.12177/emca.2020.030
Abstract:
Based on the finite element method and the lumped heat network method, the temperature rise model of the motor is established, and the transient temperature rise of the motor is simulated. In view of the variety and complexity of the model parameters of motor temperature rise, the electromagnetic parameters and thermal parameters of motor are systematically studied from the perspective of loss distribution and heat transfer. According to the structural parameters of the motor, the physical model is established. The leakage inductance parameters are modified by electromagnetic simulation and analytical calculation. The heat transfer coefficients of the end and the shell are calculated. The air gap convection coefficients of the stator and rotor are treated equivalently. The temperature rise is calculated by the magnetothermal coupling method. By comparing the temperature rise of the main parts of the motor through experiment and simulation, the accuracy of motor parameters calculation is verified.
Based on the finite element method and the lumped heat network method, the temperature rise model of the motor is established, and the transient temperature rise of the motor is simulated. In view of the variety and complexity of the model parameters of motor temperature rise, the electromagnetic parameters and thermal parameters of motor are systematically studied from the perspective of loss distribution and heat transfer. According to the structural parameters of the motor, the physical model is established. The leakage inductance parameters are modified by electromagnetic simulation and analytical calculation. The heat transfer coefficients of the end and the shell are calculated. The air gap convection coefficients of the stator and rotor are treated equivalently. The temperature rise is calculated by the magnetothermal coupling method. By comparing the temperature rise of the main parts of the motor through experiment and simulation, the accuracy of motor parameters calculation is verified.
2020, 47(6):27-32.
DOI: 10.12177/emca.2020.024
Abstract:
In order to extend the application range of single-sided permanent magnet disk generator, the optimization design of such generator is investigated. Firstly, the generator suitable for vehicle operating conditions is selected as the research object after analyzing the influence of permanent magnet thickness, air gap and shape on the generator, and comparing the performance of the generator with or without iron core. Then, a multi-objective optimization equation is established with the thickness and shape of permanent magnet as optimization variables, and the voltage waveform distortion rate and efficiency as optimization objectives by response surface method. The results show that thickness and shape of permanent magnet have significant influence on the generator performance. The efficiency of single-sided permanent magnet generator after response surface optimization is improved by 0.83%, and the total harmonic distortion (THD) is reduced by 16.7%. The optimization method has a certain reference value in the design of permanent magnet structure of single-sided disc generator.
In order to extend the application range of single-sided permanent magnet disk generator, the optimization design of such generator is investigated. Firstly, the generator suitable for vehicle operating conditions is selected as the research object after analyzing the influence of permanent magnet thickness, air gap and shape on the generator, and comparing the performance of the generator with or without iron core. Then, a multi-objective optimization equation is established with the thickness and shape of permanent magnet as optimization variables, and the voltage waveform distortion rate and efficiency as optimization objectives by response surface method. The results show that thickness and shape of permanent magnet have significant influence on the generator performance. The efficiency of single-sided permanent magnet generator after response surface optimization is improved by 0.83%, and the total harmonic distortion (THD) is reduced by 16.7%. The optimization method has a certain reference value in the design of permanent magnet structure of single-sided disc generator.
2020, 47(6):33-37.
DOI: 10.12177/emca.2020.038
Abstract:
The characteristic parameters of the stator winding insulations in the inverter-fed traction motors with various service years, including the insulation resistance, dissipation factor, partial discharge inception voltage (PDIV) and residual breakdown voltage, are measured sequentially to analyze the insulation deterioration. The insulation materials from different sites of the insulation along the windings are sampled and analyzed with thermogravimetric analysis (TGA). The measured dielectric results show that the characteristic parameters from the stator windings decrease slightly in comparison with those of new motors. The aging degree of the insulation near the outlet slot is higher than that in the slot. Besides, the TGA results from the sampled insulation materials indicate that the stator winding insulation in the inverter-fed traction motor with a service period up to ten years shows slight deterioration. Generally, more serious deterioration in the insulation tends to appear at the bottom side of the motor coils.
The characteristic parameters of the stator winding insulations in the inverter-fed traction motors with various service years, including the insulation resistance, dissipation factor, partial discharge inception voltage (PDIV) and residual breakdown voltage, are measured sequentially to analyze the insulation deterioration. The insulation materials from different sites of the insulation along the windings are sampled and analyzed with thermogravimetric analysis (TGA). The measured dielectric results show that the characteristic parameters from the stator windings decrease slightly in comparison with those of new motors. The aging degree of the insulation near the outlet slot is higher than that in the slot. Besides, the TGA results from the sampled insulation materials indicate that the stator winding insulation in the inverter-fed traction motor with a service period up to ten years shows slight deterioration. Generally, more serious deterioration in the insulation tends to appear at the bottom side of the motor coils.
2020, 47(6):38-45.
DOI: 10.12177/emca.2020.037
Abstract:
Micro motors are widely used in daily life equipment and industrial drive systems. Various countries have proposed corresponding electromagnetic compatibility standards for electronic equipment. The conducted interference and radiated interference of a micro motor system exported to Europe exceed the EN55032 standard. According to the control principle and structure of the motor, it is re-designed to improve the conducted interference and radiated interference under the condition of fixed installation size. The electromagnetic interference source and propagation path of the controller are theoretically analyzed. The components of common mode current and differential mode current are classified by Fourier transform. The interference source is weakened by adjusting the driving resistance and switching frequency and adding the RC absorption circuit, and the propagation of electromagnetic interference is suppressed through ground filtering, so that the electromagnetic interference is reduced. Experimental results show that adding filter circuit can reduce conducted interference, and adding RC absorption circuit can reduce radiated interference.
Micro motors are widely used in daily life equipment and industrial drive systems. Various countries have proposed corresponding electromagnetic compatibility standards for electronic equipment. The conducted interference and radiated interference of a micro motor system exported to Europe exceed the EN55032 standard. According to the control principle and structure of the motor, it is re-designed to improve the conducted interference and radiated interference under the condition of fixed installation size. The electromagnetic interference source and propagation path of the controller are theoretically analyzed. The components of common mode current and differential mode current are classified by Fourier transform. The interference source is weakened by adjusting the driving resistance and switching frequency and adding the RC absorption circuit, and the propagation of electromagnetic interference is suppressed through ground filtering, so that the electromagnetic interference is reduced. Experimental results show that adding filter circuit can reduce conducted interference, and adding RC absorption circuit can reduce radiated interference.
2020, 47(6):46-51.
DOI: 10.12177/emca.2020.029
Abstract:
The loss and temperature rise of high-power and high-speed permanent magnet motor affect the improvement of power density. Taking a 500 kW, 12 000 r/min high-speed permanent magnet motor as an example, the effects of the selection of pole-pair number, stator winding type, rotor structure and permanent magnet on motor performances, especially on loss, are analyzed. The finite element model of the motor is established, and the rotor structure strength, output performance and loss of the motor are analyzed and calculated. The prototype is trial-produced, and the relevant performances are tested and verified. The results show that the motor has reached a high technical target. It provides some meaningful references for the optimal design of high-speed permanent magnet motor.
The loss and temperature rise of high-power and high-speed permanent magnet motor affect the improvement of power density. Taking a 500 kW, 12 000 r/min high-speed permanent magnet motor as an example, the effects of the selection of pole-pair number, stator winding type, rotor structure and permanent magnet on motor performances, especially on loss, are analyzed. The finite element model of the motor is established, and the rotor structure strength, output performance and loss of the motor are analyzed and calculated. The prototype is trial-produced, and the relevant performances are tested and verified. The results show that the motor has reached a high technical target. It provides some meaningful references for the optimal design of high-speed permanent magnet motor.
2020, 47(6):52-57.
DOI: 10.12177/emca.2020.027
Abstract:
There are a lot of problems in the design, manufacture and operation of high-speed motor. Solving these problems by experience is time-consuming and inefficient. Using the appropriate calculation and analysis software to analyze and optimize the structure can achieve good results. It is an effective method to evaluate the vibration performance of the rotor structure by using the rotor dynamics method, and then optimize the rotor structure. Taking the rotor vibration of a double-shaft-extension motor as an example, the static deflection of the rotor is solved by the beam element method, and the rotor dynamics is analyzed by the finite element analysis software ANSYS to find out the reason of the rotor vibration, and the rotor structure is optimized according to the calculation results and the structural characteristics. The rotor structure of the doubleshaftextension motor is adjusted according to the optimization scheme, and the rotor vibration problem of the motor is solved successfully.
There are a lot of problems in the design, manufacture and operation of high-speed motor. Solving these problems by experience is time-consuming and inefficient. Using the appropriate calculation and analysis software to analyze and optimize the structure can achieve good results. It is an effective method to evaluate the vibration performance of the rotor structure by using the rotor dynamics method, and then optimize the rotor structure. Taking the rotor vibration of a double-shaft-extension motor as an example, the static deflection of the rotor is solved by the beam element method, and the rotor dynamics is analyzed by the finite element analysis software ANSYS to find out the reason of the rotor vibration, and the rotor structure is optimized according to the calculation results and the structural characteristics. The rotor structure of the doubleshaftextension motor is adjusted according to the optimization scheme, and the rotor vibration problem of the motor is solved successfully.
11 Electromagnetic and Cooling Design of 3 MW Low-Noise Compact Cage Asynchronous Wind Power Generator
2020, 47(6):58-63.
DOI: 10.12177/emca.2020.047
Abstract:
The design of a 3 MW low-noise compact cage asynchronous wind power generator is performed aiming at the development trends of cage generator including high efficiency, low noise and high power density. The calculation process of the electromagnetic and cooling schemes of the cage generator is explained. The additional loss of rotor bar caused by the air gap magnetic field is reduced by electromagnetic simulation, and the ventilation noise is calculated by fluid simulation. The design is validated with type tests. The results show that the design method is feasible and the motor has a good performance.
The design of a 3 MW low-noise compact cage asynchronous wind power generator is performed aiming at the development trends of cage generator including high efficiency, low noise and high power density. The calculation process of the electromagnetic and cooling schemes of the cage generator is explained. The additional loss of rotor bar caused by the air gap magnetic field is reduced by electromagnetic simulation, and the ventilation noise is calculated by fluid simulation. The design is validated with type tests. The results show that the design method is feasible and the motor has a good performance.
2020, 47(6):64-69.
DOI: 10.12177/emca.2020.046
Abstract:
To study the high frequency electromagnetic noise of the new energy electric vehicle during running, the noise, vibration and harshness (NVH) test and electromagnetic simulation analysis of some kind of new energy bus are carried out. Two-dimensional Fourier transform is made in the time domain and space domain on the solved electromagnetic force density, and it is determined that the electromagnetic noise is mainly caused by the 0 order 72nd harmonics according to the experimental data. The motor structural parameters of the motor rotor such as the angle between the magnetic steels, the length and width of the magnetic steel and so on, are taken as design variables to optimize the electromagnetic force density and torque ripple of the motor. Meanwhile, the multi-physics fields simulation of the electromagnetic field, structure and acoustics is made to solve the electromagnetic noise with the finite element method based on the optimized model, and the NVH tests of the vehicle are carried out to validate the simulation results. Test results show that the overall noise of the vehicle is reduced by 8.53 dB(A), the maximum noise of the 72nd harmonics of the motor is reduced by 18.59 dB(A), and the maximum 7th order noise of the gearbox is reduced by 5.02 dB(A). Simulation results are consistent with experimental test results.
To study the high frequency electromagnetic noise of the new energy electric vehicle during running, the noise, vibration and harshness (NVH) test and electromagnetic simulation analysis of some kind of new energy bus are carried out. Two-dimensional Fourier transform is made in the time domain and space domain on the solved electromagnetic force density, and it is determined that the electromagnetic noise is mainly caused by the 0 order 72nd harmonics according to the experimental data. The motor structural parameters of the motor rotor such as the angle between the magnetic steels, the length and width of the magnetic steel and so on, are taken as design variables to optimize the electromagnetic force density and torque ripple of the motor. Meanwhile, the multi-physics fields simulation of the electromagnetic field, structure and acoustics is made to solve the electromagnetic noise with the finite element method based on the optimized model, and the NVH tests of the vehicle are carried out to validate the simulation results. Test results show that the overall noise of the vehicle is reduced by 8.53 dB(A), the maximum noise of the 72nd harmonics of the motor is reduced by 18.59 dB(A), and the maximum 7th order noise of the gearbox is reduced by 5.02 dB(A). Simulation results are consistent with experimental test results.
2020, 47(6):70-75.
DOI: 10.12177/emca.2020.044
Abstract:
In automotive electric power steering (EPS) system, the dead-time problem of the inverter is the main factor affecting the output performance of the steering motor, which is manifested by an increase in the current harmonic content. The dead-time problem causes motor torque ripple and increases the additional loss of the motor. The dual three-phase permanent magnet synchronous motors adopt two sets of stator windings with 30° phase shift. The content of the sixth harmonic current is reduced by the double dq coordinate transformation control, and the total harmonic content of electromagnetic torque is reduced. Simulation results show that the proposed method is correct and effective.
In automotive electric power steering (EPS) system, the dead-time problem of the inverter is the main factor affecting the output performance of the steering motor, which is manifested by an increase in the current harmonic content. The dead-time problem causes motor torque ripple and increases the additional loss of the motor. The dual three-phase permanent magnet synchronous motors adopt two sets of stator windings with 30° phase shift. The content of the sixth harmonic current is reduced by the double dq coordinate transformation control, and the total harmonic content of electromagnetic torque is reduced. Simulation results show that the proposed method is correct and effective.
2020, 47(6):76-81.
DOI: 10.12177/emca.2020.035
Abstract:
The electromagnetic noise of permanent magnet synchronous motor (PMSM) for vehicles is the main source of new energy vehicle noise, which directly affects the vibration and noise characteristics of the vehicle. The low-order radial electromagnetic force acting on the stator structure of the motor is the main reason for the electromagnetic noise of the motor. Taking a PMSM for new energy vehicle with a rated power of 35 kW as the research object, an optimization method with auxiliary slots on the outer edge of the rotor is proposed to reduce the vibration and noise of the motor. The optimal parameter values are determined by multivariate optimization of multiple parameters of the auxiliary slot. The finite element method is used to compare the vibration and noise of the motor with and without the auxiliary slots. Finally, the correctness of the method is verified by the vibration and noise experiment of the prototype. Through the optimization of the rotor with auxiliary slots, the amplitude of the motor vibration acceleration is reduced by 2g and the noise is reduced by 4 dB.
The electromagnetic noise of permanent magnet synchronous motor (PMSM) for vehicles is the main source of new energy vehicle noise, which directly affects the vibration and noise characteristics of the vehicle. The low-order radial electromagnetic force acting on the stator structure of the motor is the main reason for the electromagnetic noise of the motor. Taking a PMSM for new energy vehicle with a rated power of 35 kW as the research object, an optimization method with auxiliary slots on the outer edge of the rotor is proposed to reduce the vibration and noise of the motor. The optimal parameter values are determined by multivariate optimization of multiple parameters of the auxiliary slot. The finite element method is used to compare the vibration and noise of the motor with and without the auxiliary slots. Finally, the correctness of the method is verified by the vibration and noise experiment of the prototype. Through the optimization of the rotor with auxiliary slots, the amplitude of the motor vibration acceleration is reduced by 2g and the noise is reduced by 4 dB.
2020, 47(6):82-87.
DOI: 10.12177/emca.2020.053
Abstract:
Most diesel generator speed control systems use traditional PID control. An iterative learning control (ILC) strategy that takes PID as the learning law is proposed. Making use of the characteristics of ILC of accurate mathematical modeling independent of the controlled system and fast tracking convergence, the diesel generator speed control system controller is designed. In MATLAB/Simulink, a simulation model of the diesel generator speed control system is established. Three basic working conditions are simulated and studied. The tracking characteristics of the ILC in the diesel generator speed control process are analyzed in detail, and the control effects of the proposed control and traditional PID control are compared. The results show that the controller based on ILC is not only suitable for the diesel generator speed control system, but also has better dynamic performance. A new way is provided for the control of diesel generators.
Most diesel generator speed control systems use traditional PID control. An iterative learning control (ILC) strategy that takes PID as the learning law is proposed. Making use of the characteristics of ILC of accurate mathematical modeling independent of the controlled system and fast tracking convergence, the diesel generator speed control system controller is designed. In MATLAB/Simulink, a simulation model of the diesel generator speed control system is established. Three basic working conditions are simulated and studied. The tracking characteristics of the ILC in the diesel generator speed control process are analyzed in detail, and the control effects of the proposed control and traditional PID control are compared. The results show that the controller based on ILC is not only suitable for the diesel generator speed control system, but also has better dynamic performance. A new way is provided for the control of diesel generators.
2020, 47(6):88-92.
DOI: 10.12177/emca.2020.049
Abstract:
Power grid voltage sag often causes protection action of the coal feeder frequency converter in the thermal power plant, which affects the normal power production. A novel means of using the permanent magnet coupling speed regulating motor in coal feeder is proposed to realize low voltage ride-through (LVRT) by the motor′s properties. The LVRT operating principle of the permanent magnet coupling speed regulating motor is analyzed. The double-closed-loop control system is designed. A 5.5 kW electrical drive system experimental platform of the coal feeder is built. The experimental results show that the proposed motor and its control system have good rapidity and accuracy, and when voltage sag occurs in the power grid, the coal feeder can work normally and have LVRT ability.
Power grid voltage sag often causes protection action of the coal feeder frequency converter in the thermal power plant, which affects the normal power production. A novel means of using the permanent magnet coupling speed regulating motor in coal feeder is proposed to realize low voltage ride-through (LVRT) by the motor′s properties. The LVRT operating principle of the permanent magnet coupling speed regulating motor is analyzed. The double-closed-loop control system is designed. A 5.5 kW electrical drive system experimental platform of the coal feeder is built. The experimental results show that the proposed motor and its control system have good rapidity and accuracy, and when voltage sag occurs in the power grid, the coal feeder can work normally and have LVRT ability.
2020, 47(6):93-96.
DOI: 10.12177/emca.2020.039
Abstract:
Current sharing control of parallel operation between power modules is a common problem in practical applications. In view of problems with low current sharing accuracy, poor stability and low anti-interference ability in current sharing control of parallel operation of power modules, a method of current sharing control with voltage loop and double-current-loop is proposed. Output voltage of DC power module is sampled, and the external voltage loop is formed to stabilize the output voltage. Maximum current sharing method is used to control the output current of module and form the external current loop. Main circuit current of each module is connected to the processor through sampling circuit to form the internal current loop. In this way, the accuracy of output current and current sharing can be ensured. Voltage loop and double-current-loop are modulated by the processor, generating PWM to control each DC power module. Through simulation analysis and tests of two 4 000 W prototypes, it is verified that the current sharing method controlled by voltage loop and double-current-loop has the advantages of high current sharing accuracy, good stability and strong anti-interference ability.
Current sharing control of parallel operation between power modules is a common problem in practical applications. In view of problems with low current sharing accuracy, poor stability and low anti-interference ability in current sharing control of parallel operation of power modules, a method of current sharing control with voltage loop and double-current-loop is proposed. Output voltage of DC power module is sampled, and the external voltage loop is formed to stabilize the output voltage. Maximum current sharing method is used to control the output current of module and form the external current loop. Main circuit current of each module is connected to the processor through sampling circuit to form the internal current loop. In this way, the accuracy of output current and current sharing can be ensured. Voltage loop and double-current-loop are modulated by the processor, generating PWM to control each DC power module. Through simulation analysis and tests of two 4 000 W prototypes, it is verified that the current sharing method controlled by voltage loop and double-current-loop has the advantages of high current sharing accuracy, good stability and strong anti-interference ability.
2020, 47(6):97-102.
DOI: 10.12177/emca.2020.034
Abstract:
In photovoltaic storage microgrid system, anti-interference ability of battery energy storage is weak, DC bus voltage fluctuation is large, and charging and discharging efficiency is poor. In order to solve these problems, a battery energy storage control strategy based on feedforward linear active disturbance rejection control method (FF-LADRC) is proposed. A mathematical model of bi-directional DC-DC converter is established. Based on the traditional closed-loop energy storage control of a battery, by introducing LADRC into the voltage loop and the current loop respectively, and adding a feedforward control in the voltage loop, the double-closed-loop control strategy is improved. Thereby the charging and discharging process in the battery energy storage system is controlled effectively. Simulation results show that the proposed control method can suppress the DC bus voltage fluctuation, and improve the charging and discharging performance of the battery energy storage system and reduce the overshoot of the energy storage system effectively.
In photovoltaic storage microgrid system, anti-interference ability of battery energy storage is weak, DC bus voltage fluctuation is large, and charging and discharging efficiency is poor. In order to solve these problems, a battery energy storage control strategy based on feedforward linear active disturbance rejection control method (FF-LADRC) is proposed. A mathematical model of bi-directional DC-DC converter is established. Based on the traditional closed-loop energy storage control of a battery, by introducing LADRC into the voltage loop and the current loop respectively, and adding a feedforward control in the voltage loop, the double-closed-loop control strategy is improved. Thereby the charging and discharging process in the battery energy storage system is controlled effectively. Simulation results show that the proposed control method can suppress the DC bus voltage fluctuation, and improve the charging and discharging performance of the battery energy storage system and reduce the overshoot of the energy storage system effectively.
2020, 47(6):103-109.
DOI: 10.12177/emca.2020.032
Abstract:
In order to enhance the power quality of the 220 kV supply grid of a distribution substation, a novel inductive filtering (IF) method with a four-winding inductive filtering transformer (FW-IFT) connected to passive filters is proposed to prevent the main load harmonic current from flowing into the supply grid. A new IF scheme is introduced and the IF mechanism of the FW-IFT is analyzed in detail. Then, the voltage equations of the FW-IFT under fundamental and harmonic frequencies are established based on the radial circuit, and the filtering performance is analyzed. Finally, the effectiveness and feasibility of the proposed method is verified by MATLAB simulation and prototype experiment.
In order to enhance the power quality of the 220 kV supply grid of a distribution substation, a novel inductive filtering (IF) method with a four-winding inductive filtering transformer (FW-IFT) connected to passive filters is proposed to prevent the main load harmonic current from flowing into the supply grid. A new IF scheme is introduced and the IF mechanism of the FW-IFT is analyzed in detail. Then, the voltage equations of the FW-IFT under fundamental and harmonic frequencies are established based on the radial circuit, and the filtering performance is analyzed. Finally, the effectiveness and feasibility of the proposed method is verified by MATLAB simulation and prototype experiment.
2020, 47(6):110-118.
DOI: 10.12177/emca.2020.011
Abstract:
Taking into account the frequency-modulation characteristics of doubly-fed induction generator(DFIG), the equivalent impedance model of DFIG for transient power angle stability analysis is established. For the extended dualmachine system with DFIG, it is equivalent to an extended single-machine infinite-bus system. Based on the equal-area criterion, the expression of the limit clearing angle about the wind power proportion and the droop coefficient in frequency-modulation control is derived. The change trend of the limit clearing angle of the system with the wind power proportion and droop coefficient of DFIG is analyzed theoretically, and the internal mechanism of the change is revealed in combination with the trend of power-angle characteristics. Considering the low-voltage ride-through characteristics and frequency-modulation control of DFIG, a detailed model of DFIG is built in PSD-BPA. The extended dual-machine system with detailed wind power model and Yunnan power grid simulation model are built to verify the theoretical analysis results. Theoretical analysis and simulation results show that DFIG participating in frequency-modulation can improve the transient power angle stability.
Taking into account the frequency-modulation characteristics of doubly-fed induction generator(DFIG), the equivalent impedance model of DFIG for transient power angle stability analysis is established. For the extended dualmachine system with DFIG, it is equivalent to an extended single-machine infinite-bus system. Based on the equal-area criterion, the expression of the limit clearing angle about the wind power proportion and the droop coefficient in frequency-modulation control is derived. The change trend of the limit clearing angle of the system with the wind power proportion and droop coefficient of DFIG is analyzed theoretically, and the internal mechanism of the change is revealed in combination with the trend of power-angle characteristics. Considering the low-voltage ride-through characteristics and frequency-modulation control of DFIG, a detailed model of DFIG is built in PSD-BPA. The extended dual-machine system with detailed wind power model and Yunnan power grid simulation model are built to verify the theoretical analysis results. Theoretical analysis and simulation results show that DFIG participating in frequency-modulation can improve the transient power angle stability.
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Electric Machines & Control Application ® 2025
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沪ICP备16038578号-3
Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
