In general,Variable-Speed Constant Frequency (VSCF)Wind generation system is controlled by stator voltage orientation method which based on the mathematic model of VSCF Wind generation system and discussed the control...In general,Variable-Speed Constant Frequency (VSCF)Wind generation system is controlled by stator voltage orientation method which based on the mathematic model of VSCF Wind generation system and discussed the control strategy.Present the whole dynamic control model of variable-speed wind generator system in MATLAB/ Simulink,and the simulation results confirm the validity and effectiveness of the proposed control strategy.展开更多
Main Exhauster is one of the main equipment of sintering production. It needs to consume a lot of electricity. Therefore, the system' s reconstruction for energy-saving will effectively reduce electricity for the pro...Main Exhauster is one of the main equipment of sintering production. It needs to consume a lot of electricity. Therefore, the system' s reconstruction for energy-saving will effectively reduce electricity for the production. The paper takes an iron and steel enterprise that had successfully transformed the synchronous motors of main exhauster of sintering as an example, which describes the application of high-voltage variable frequency speed regulation system in main exhauster of Sintering, so as to provide a reference for other iron and steel enterprises.展开更多
Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum ...Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power.The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most.We presented a novel maximum power point tracking(MPPT)control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid.The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve,which had excellent dynamic and static performances and robustness.Simulation and experimental results testify the accuracy and validity of the control strategy.展开更多
Focused on the non-statlonarity and real-time analysis of signal in flutter test with progression variable speed (FTPVS), a new method of recursive time-frequency analysis is presented. The time-varying system is tr...Focused on the non-statlonarity and real-time analysis of signal in flutter test with progression variable speed (FTPVS), a new method of recursive time-frequency analysis is presented. The time-varying system is tracked on-line by building a time-varying parameter model, and then the relevant parameter spectrum can be obtained. The feasibility and advantages of the method are examined by digital simulation. The results of FTPVS at low-speed wind-tunnel promise the engineering application perspective of the method.展开更多
in this paper, an electromechanically coupled mathematic model of multi-roller driving system for belt conveyor is set up, and the computing equations for dynamic displacement and dynamic tension of the conveyor are a...in this paper, an electromechanically coupled mathematic model of multi-roller driving system for belt conveyor is set up, and the computing equations for dynamic displacement and dynamic tension of the conveyor are also formulated when the hoister is used for straining. Based on the belt conveyor of main inclined shaft in Chengzhuang coal mine, the driving torque, driving power and starting-speed characteristic of each electric motor are studied and measured when multi-roller variable-frequency drive (power distribution 2∶1) is used. The optimal control and the optimal starting-acceleration of the multi-roller variable-frequency drive are determined by a large number of industrial experiments and theoretical calculations.展开更多
The paper presents a reliability evaluation method based on fault tree analysis with set theory and minimal cut set as core algorithm, which can be used to evaluate the reliability for industrial grids with wide appli...The paper presents a reliability evaluation method based on fault tree analysis with set theory and minimal cut set as core algorithm, which can be used to evaluate the reliability for industrial grids with wide application of variable frequency drives. The working principle is introduced firstly, based on which the method development considering different system topology designs, backup solutions and redundancy mechanisms are analyzed in details. In the end the proposed method is applied to two cases to show the reliability performance of system with variable frequency drives. The proposed method is also suitable for analyzing the reliability performance of industrial grids with other types of power electronic converter technology.展开更多
In the paper, the method to optimize the rotor structure in variable frequency speed control motors is introduced. The saturation and the skin effect are considered and 2D no-load and load electromagnetic field is cal...In the paper, the method to optimize the rotor structure in variable frequency speed control motors is introduced. The saturation and the skin effect are considered and 2D no-load and load electromagnetic field is calculated in finite elements for a variable frequency speed control motor before and after optimization. Finally, no-load current and operation performance before and after optimization are obtained and the two results are contrasted.展开更多
This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The...This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip's PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM (sinusoidal pulse width modulation) switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control" automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated.展开更多
VFDs (variable frequency drives) are an integral part of many industrial plants and stations. Reliable operation and maintenance of these drives is vital to ensure sustained plant operation and availability. Underst...VFDs (variable frequency drives) are an integral part of many industrial plants and stations. Reliable operation and maintenance of these drives is vital to ensure sustained plant operation and availability. Understanding of the principles of operation of VFD systems as well as knowledge about their required operating environment is necessary for all operating personnel. Many times the operating personnel do not get involved with different technical issues until a complete failure has occurred. Hence, the awareness of the most dominant failure causes has a significant impact on assisting operators to avoid catastrophic failures and tremendous economic losses due to VFD shutdown. Proper plant design, accurate monitoring and data logging, following manufacturer preventive maintenance schedule, and choosing qualified team of operators can be the key to an efficient operation and a long lifetime for any VFD system. In this paper, we have analyzed the electrical and non-electrical causes of VFD failures based on a case study of a typical medium voltage VFD pumping station. Finally, recommendations are given from field analysis and observations.展开更多
Cavitation in pumps must be detected and prevented. The present work is an attempt to use the simultaneous measurements of vibration and sound for variable speed pump to detect cavitation. It is an attempt to declare ...Cavitation in pumps must be detected and prevented. The present work is an attempt to use the simultaneous measurements of vibration and sound for variable speed pump to detect cavitation. It is an attempt to declare the relationship between the vibration and sound for the same discharge of 780 L/h and NPSHA of 0.754 at variable speeds of 1476 rpm, 1644 rpm, 1932 rpm, 2190 rpm, 2466 rpm, and 2682 rpm. Results showed that: the occurrence of cavitation depends on the rotational speed, and the sound signals in both no cavitation and cavitation conditions appear in random manner. While, surveying the vibration and sound spectrums at the second, third, and fourth blade passing frequencies reveals no indications or phenomenon associated with the cavitation at variable speeds. It is recommended to survey the vibration spectra at the rotational and blade passing frequencies simultaneously as a detection unique method of cavitation.展开更多
The aim of this paper is to analyze the potential of switched reluctance generator (SRG) in wind energy application. The machine comprises of switched reluctance generator, power converter and controller. In this pape...The aim of this paper is to analyze the potential of switched reluctance generator (SRG) in wind energy application. The machine comprises of switched reluctance generator, power converter and controller. In this paper the main ele-ments that form the generator system is discussed. It also highlights the common type of converter and structure used for SRG in wind energy application and types of control strategy available. Using power converter for switching the generator can operate over a wide speed range. Its applications in high speed area such as starter/generator for air-craft and gas turbine has been established, however the low/medium speed operation is still at an early stage of re-search. In order to subject the machine to various parameters, offline modeling is being investigated to produce the best optimum design.展开更多
Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optim...Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering fouling.However,low flow velocity promotes fouling.Therefore,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term operation.This study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this goal.The model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and fouling.By optimizing the concentration cycle of the CCWS,water conservation and fouling control can be achieved.The model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance coefficient.Sensitivity experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation decrease.In periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling rate.Overall,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.展开更多
This paper presents a variable speed control strategy for wind turbines in order to capture maximum wind power.Wind turbines are modeled as a two-mass drive-train system with generator torque control.Based on the obta...This paper presents a variable speed control strategy for wind turbines in order to capture maximum wind power.Wind turbines are modeled as a two-mass drive-train system with generator torque control.Based on the obtained wind turbine model,variable speed control schemes are developed.Nonlinear tracking controllers are designed to achieve asymptotic tracking for a prescribed rotor speed reference signal so as to yield maximum wind power capture.Due to the difficulty of torsional angle measurement,an observer-based control scheme that uses only rotor speed information is further developed for global asymptotic output tracking.The effectiveness of the proposed control methods is illustrated by simulation results.展开更多
This paper decribes the control of a high performance variable reluctance motor system for direct drive robotics and industrial automation. The control system of a motor comists of a drive unit and a digital controlle...This paper decribes the control of a high performance variable reluctance motor system for direct drive robotics and industrial automation. The control system of a motor comists of a drive unit and a digital controller, possessing two functions of tbe analog dosed-loop control of motor velocity and the digit dosed-loop control of motor position. Then it discusses the closed-loop control of current in the three phases of the motor and the control of the lead angle of the motor. Finally, it suggests a design of the control circuits of motor current, velocity and position. The closed loop control of the motor position is achieved by a digit cotroller which consists of a microprocessor and other electronic components. It can control two variable reluctance motors simultaneusly. In order to be used for directly driving robots, the digit cotroller is equipped with a universal interface.展开更多
In industrial drives, electric motors are extensively utilized to impart motion control and induction motors are the most familiar drive at present due to its extensive performance characteristic similar with that of ...In industrial drives, electric motors are extensively utilized to impart motion control and induction motors are the most familiar drive at present due to its extensive performance characteristic similar with that of DC drives. Precise control of drives is the main attribute in industries to optimize the performance and to increase its production rate. In motion control, the major considerations are the torque and speed ripples. Design of controllers has become increasingly complex to such systems for better management of energy and raw materials to attain optimal performance. Meager parameter appraisal results are unsuitable, leading to unstable operation. The rapid intensification of digital computer revolutionizes to practice precise control and allows implementation of advanced control strategy to extremely multifaceted systems. To solve complex control problems, model predictive control is an authoritative scheme, which exploits an explicit model of the process to be controlled. This paper presents a predictive control strategy by a neural network predictive controller based single phase induction motor drive to minimize the speed and torque ripples. The proposed method exhibits better performance than the conventional controller and validity of the proposed method is verified by the simulation results using MATLAB software.展开更多
This paper presents a solution to the circulating current fault of aircraft power supply.The DC-link type Variable Frequency to Constant Frequency(VFCF)converter system is the preferred scheme to feed the constant 400...This paper presents a solution to the circulating current fault of aircraft power supply.The DC-link type Variable Frequency to Constant Frequency(VFCF)converter system is the preferred scheme to feed the constant 400 Hz load in an aircraft with a variable frequency power supply.Due to the requirement of aircraft standards,both grounds of the rectification and inversion stage are tied to the metal frame of the aircraft.With such a tied ground,the DC bus voltage rises greatly,and a large circulating current appears in the casing as the ground,which leads to equipment failure and potential safety hazards.According to the existing methods of circulating current fault suppression,this paper analyzes the causes of the above faults and the harmonic components of circulating current and points out the limitations of the existing methods.Therefore,a Common-Mode(CM)choke-based method is proposed to provide a high impedance in the path of the CM circulating current.By doing so,the circulating current can be suppressed without the additional burden of the hardware and control algorithm,which is quite friendly for quality control of mass-production aircraft.Moreover,a simplified mathematic model of the VFCF converter system is derived to calculate the minimum inductance value reference of the CM choke,which saves the weight of passive devices to the greatest extent.Finally,simulation and experimental results are studied to verify the effectiveness of the proposed method.展开更多
文摘In general,Variable-Speed Constant Frequency (VSCF)Wind generation system is controlled by stator voltage orientation method which based on the mathematic model of VSCF Wind generation system and discussed the control strategy.Present the whole dynamic control model of variable-speed wind generator system in MATLAB/ Simulink,and the simulation results confirm the validity and effectiveness of the proposed control strategy.
文摘Main Exhauster is one of the main equipment of sintering production. It needs to consume a lot of electricity. Therefore, the system' s reconstruction for energy-saving will effectively reduce electricity for the production. The paper takes an iron and steel enterprise that had successfully transformed the synchronous motors of main exhauster of sintering as an example, which describes the application of high-voltage variable frequency speed regulation system in main exhauster of Sintering, so as to provide a reference for other iron and steel enterprises.
基金Funded by the National Natural Science Foundation of China(No.60974049)the Science and Technology Support Industrial Project of Jiangsu Province(No.BZ2008031,No.BE2008074,and No.BE2009090)+1 种基金the Nantong International Cooperative Project(No.W2009003)the Natural Science Foundation of Nantong University(No.08Z022 and No.08Z025).
文摘Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power.The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most.We presented a novel maximum power point tracking(MPPT)control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid.The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve,which had excellent dynamic and static performances and robustness.Simulation and experimental results testify the accuracy and validity of the control strategy.
文摘Focused on the non-statlonarity and real-time analysis of signal in flutter test with progression variable speed (FTPVS), a new method of recursive time-frequency analysis is presented. The time-varying system is tracked on-line by building a time-varying parameter model, and then the relevant parameter spectrum can be obtained. The feasibility and advantages of the method are examined by digital simulation. The results of FTPVS at low-speed wind-tunnel promise the engineering application perspective of the method.
文摘in this paper, an electromechanically coupled mathematic model of multi-roller driving system for belt conveyor is set up, and the computing equations for dynamic displacement and dynamic tension of the conveyor are also formulated when the hoister is used for straining. Based on the belt conveyor of main inclined shaft in Chengzhuang coal mine, the driving torque, driving power and starting-speed characteristic of each electric motor are studied and measured when multi-roller variable-frequency drive (power distribution 2∶1) is used. The optimal control and the optimal starting-acceleration of the multi-roller variable-frequency drive are determined by a large number of industrial experiments and theoretical calculations.
文摘The paper presents a reliability evaluation method based on fault tree analysis with set theory and minimal cut set as core algorithm, which can be used to evaluate the reliability for industrial grids with wide application of variable frequency drives. The working principle is introduced firstly, based on which the method development considering different system topology designs, backup solutions and redundancy mechanisms are analyzed in details. In the end the proposed method is applied to two cases to show the reliability performance of system with variable frequency drives. The proposed method is also suitable for analyzing the reliability performance of industrial grids with other types of power electronic converter technology.
文摘In the paper, the method to optimize the rotor structure in variable frequency speed control motors is introduced. The saturation and the skin effect are considered and 2D no-load and load electromagnetic field is calculated in finite elements for a variable frequency speed control motor before and after optimization. Finally, no-load current and operation performance before and after optimization are obtained and the two results are contrasted.
文摘This paper presents an electronic VSD (variable speed drive) for three-phase IM (induction motor) using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip's PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM (sinusoidal pulse width modulation) switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control" automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated.
文摘VFDs (variable frequency drives) are an integral part of many industrial plants and stations. Reliable operation and maintenance of these drives is vital to ensure sustained plant operation and availability. Understanding of the principles of operation of VFD systems as well as knowledge about their required operating environment is necessary for all operating personnel. Many times the operating personnel do not get involved with different technical issues until a complete failure has occurred. Hence, the awareness of the most dominant failure causes has a significant impact on assisting operators to avoid catastrophic failures and tremendous economic losses due to VFD shutdown. Proper plant design, accurate monitoring and data logging, following manufacturer preventive maintenance schedule, and choosing qualified team of operators can be the key to an efficient operation and a long lifetime for any VFD system. In this paper, we have analyzed the electrical and non-electrical causes of VFD failures based on a case study of a typical medium voltage VFD pumping station. Finally, recommendations are given from field analysis and observations.
文摘Cavitation in pumps must be detected and prevented. The present work is an attempt to use the simultaneous measurements of vibration and sound for variable speed pump to detect cavitation. It is an attempt to declare the relationship between the vibration and sound for the same discharge of 780 L/h and NPSHA of 0.754 at variable speeds of 1476 rpm, 1644 rpm, 1932 rpm, 2190 rpm, 2466 rpm, and 2682 rpm. Results showed that: the occurrence of cavitation depends on the rotational speed, and the sound signals in both no cavitation and cavitation conditions appear in random manner. While, surveying the vibration and sound spectrums at the second, third, and fourth blade passing frequencies reveals no indications or phenomenon associated with the cavitation at variable speeds. It is recommended to survey the vibration spectra at the rotational and blade passing frequencies simultaneously as a detection unique method of cavitation.
文摘The aim of this paper is to analyze the potential of switched reluctance generator (SRG) in wind energy application. The machine comprises of switched reluctance generator, power converter and controller. In this paper the main ele-ments that form the generator system is discussed. It also highlights the common type of converter and structure used for SRG in wind energy application and types of control strategy available. Using power converter for switching the generator can operate over a wide speed range. Its applications in high speed area such as starter/generator for air-craft and gas turbine has been established, however the low/medium speed operation is still at an early stage of re-search. In order to subject the machine to various parameters, offline modeling is being investigated to produce the best optimum design.
基金Financial support from the National Natural Science Foundation of China (22022816 and 22078358)
文摘Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering fouling.However,low flow velocity promotes fouling.Therefore,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term operation.This study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this goal.The model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and fouling.By optimizing the concentration cycle of the CCWS,water conservation and fouling control can be achieved.The model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance coefficient.Sensitivity experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation decrease.In periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling rate.Overall,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.
基金supported by the Key Project of National Natural Science Foundation of China(61533009)the 111 Project(B08015)the Research Projects(KQC201105300002A,JCY20130329152125731,JCYJ20150403161923519)
文摘This paper presents a variable speed control strategy for wind turbines in order to capture maximum wind power.Wind turbines are modeled as a two-mass drive-train system with generator torque control.Based on the obtained wind turbine model,variable speed control schemes are developed.Nonlinear tracking controllers are designed to achieve asymptotic tracking for a prescribed rotor speed reference signal so as to yield maximum wind power capture.Due to the difficulty of torsional angle measurement,an observer-based control scheme that uses only rotor speed information is further developed for global asymptotic output tracking.The effectiveness of the proposed control methods is illustrated by simulation results.
文摘This paper decribes the control of a high performance variable reluctance motor system for direct drive robotics and industrial automation. The control system of a motor comists of a drive unit and a digital controller, possessing two functions of tbe analog dosed-loop control of motor velocity and the digit dosed-loop control of motor position. Then it discusses the closed-loop control of current in the three phases of the motor and the control of the lead angle of the motor. Finally, it suggests a design of the control circuits of motor current, velocity and position. The closed loop control of the motor position is achieved by a digit cotroller which consists of a microprocessor and other electronic components. It can control two variable reluctance motors simultaneusly. In order to be used for directly driving robots, the digit cotroller is equipped with a universal interface.
文摘In industrial drives, electric motors are extensively utilized to impart motion control and induction motors are the most familiar drive at present due to its extensive performance characteristic similar with that of DC drives. Precise control of drives is the main attribute in industries to optimize the performance and to increase its production rate. In motion control, the major considerations are the torque and speed ripples. Design of controllers has become increasingly complex to such systems for better management of energy and raw materials to attain optimal performance. Meager parameter appraisal results are unsuitable, leading to unstable operation. The rapid intensification of digital computer revolutionizes to practice precise control and allows implementation of advanced control strategy to extremely multifaceted systems. To solve complex control problems, model predictive control is an authoritative scheme, which exploits an explicit model of the process to be controlled. This paper presents a predictive control strategy by a neural network predictive controller based single phase induction motor drive to minimize the speed and torque ripples. The proposed method exhibits better performance than the conventional controller and validity of the proposed method is verified by the simulation results using MATLAB software.
基金supported by the Natural Science Foundation for Young Scientists of Shanxi Province,China(No.52007154).
文摘This paper presents a solution to the circulating current fault of aircraft power supply.The DC-link type Variable Frequency to Constant Frequency(VFCF)converter system is the preferred scheme to feed the constant 400 Hz load in an aircraft with a variable frequency power supply.Due to the requirement of aircraft standards,both grounds of the rectification and inversion stage are tied to the metal frame of the aircraft.With such a tied ground,the DC bus voltage rises greatly,and a large circulating current appears in the casing as the ground,which leads to equipment failure and potential safety hazards.According to the existing methods of circulating current fault suppression,this paper analyzes the causes of the above faults and the harmonic components of circulating current and points out the limitations of the existing methods.Therefore,a Common-Mode(CM)choke-based method is proposed to provide a high impedance in the path of the CM circulating current.By doing so,the circulating current can be suppressed without the additional burden of the hardware and control algorithm,which is quite friendly for quality control of mass-production aircraft.Moreover,a simplified mathematic model of the VFCF converter system is derived to calculate the minimum inductance value reference of the CM choke,which saves the weight of passive devices to the greatest extent.Finally,simulation and experimental results are studied to verify the effectiveness of the proposed method.