内部绝缘不足是引起换流站交流滤波器(alternating current filter,ACF)断路器发生爆炸事故的原因之一,为此开展了典型ACF断路器灭弧室内部电场分布的仿真研究。首先,基于电场数值分析理论,采用Solidworks和ANSYS软件建立了4种典型550 k...内部绝缘不足是引起换流站交流滤波器(alternating current filter,ACF)断路器发生爆炸事故的原因之一,为此开展了典型ACF断路器灭弧室内部电场分布的仿真研究。首先,基于电场数值分析理论,采用Solidworks和ANSYS软件建立了4种典型550 kV ACF断路器三维数值仿真模型;然后,仿真分析了弧触头网格剖分尺寸对灭弧室电场计算结果的影响,基于仿真数据对比分析了4种结构的ACF断路器在熄弧后开断过程中灭弧室的电场分布和不均匀系数,评估了断路器灭弧室内部相对绝缘强度;最后,分析了燃弧时间和平均开断速度对典型ACF断路器灭弧室电场的影响,初步提出了优化措施。仿真分析结果表明:弧触头的剖分尺寸可取0.2~0.5 mm;4种典型结构ACF断路器灭弧室内电场分布属于稍不均匀场,在正常开断情况下都能满足绝缘裕度要求;增加燃弧时间和平均开断速度,能够减小典型ACF断路器灭弧室各部件最大场强,提高绝缘裕度。展开更多
Control strategies play a key role for operation of electric machines,which would directly affect the whole system performance.In fact,different control strategies have been executed and explored for electric machines...Control strategies play a key role for operation of electric machines,which would directly affect the whole system performance.In fact,different control strategies have been executed and explored for electric machines,which bring great impacts to industrial development and human society.This paper investigates and discusses the advantages control strategies for electric machines,including the field oriented control(FOC),direct torque control(DTC),finite control set model predictive control(FCS-MPC),sensorless control,and fault tolerant control(FTC).The corresponding control principles,control targets,fundamental approaches,advanced approaches,methodologies,merits and shortcomings are revealed and analyzed in detail.展开更多
Air-gap magnetic field modulation has been widely observed in electric machines.In this study,we present an analytical analysis and performance characterization of brushless doubly fed induction machines(BDFIMs)fed by...Air-gap magnetic field modulation has been widely observed in electric machines.In this study,we present an analytical analysis and performance characterization of brushless doubly fed induction machines(BDFIMs)fed by two independent converters from the perspective of air-gap field modulation.The spiral-loop winding is studied in detail as an example to show the generalized workflow that can also be used to analyze other short-circuited rotor winding types,such as nested-loop and multiphase double-layer windings.Magnetic field conversion factors are introduced to characterize the modulation behavior of special rotor windings and facilitate their comparison in terms of cross-coupling capability,average torque,and harmonic content of the air-gap flux density waveforms.The stator magnetomotive force(MMF),rotor MMF,and resultant air-gap MMF are considered,based on which the closed-form inductance formulas are derived,and the torque equation is obtained along with the optimal current angle for maximum torque operation by using the virtual work principle.The design equations are then developed for the initial sizing and geometry scaling of the BDFIMs.Transient finite element analysis and experimental measurements are performed to validate the analysis.展开更多
The characteristics of the packing material under an alternating electric field are an important factor in the removal of FCCS particles.In this study,the electric field distribution of a separation unit consisting of...The characteristics of the packing material under an alternating electric field are an important factor in the removal of FCCS particles.In this study,the electric field distribution of a separation unit consisting of packed spheres under an alternating electric field is simulated,and the movement mechanism of catalyst particles is analysed.An"effective contact point"model is derived to predict the adsorption of filler contact points on catalyst particles under the alternating electric field,and the model is validated by simulations and experiments.The numerical calculation and experimental results indicate that the electrical properties of the filler spheres,the filler angleθ,and the frequency f of the alternating electric field affect the adsorption of catalyst particles.As the frequency of the electric field increases,the particle removal efficiency of the high-conductivity filler(silicon carbide)increases and then settles,and the separation efficiency of the low-conductivity filler(glass,zirconia)is not sensitive to the change in electric field frequency.展开更多
A versatile analytical method(VAM) for calculating the harmonic components of the magnetomotive force(MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method ha...A versatile analytical method(VAM) for calculating the harmonic components of the magnetomotive force(MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method has been established in early literature. However, its practical applications and significance in advancing the analysis of AC machines need further elaboration. This paper aims to complement VAM by augmenting its theory, offering additional insights into its conclusions, as well as demonstrating its utility in assessing armature windings and its application of calculating torque for permanent magnet synchronous machines(PMSM). This work contributes to advancing the analysis of AC machines and underscores the potential for improved design and performance optimization.展开更多
基金Supported by the general program of National Natural Science Foundation of China under Grant 51677159a grant(Project No.CityU 21201216)from the Research Grants Council of HKSAR,China.
文摘Control strategies play a key role for operation of electric machines,which would directly affect the whole system performance.In fact,different control strategies have been executed and explored for electric machines,which bring great impacts to industrial development and human society.This paper investigates and discusses the advantages control strategies for electric machines,including the field oriented control(FOC),direct torque control(DTC),finite control set model predictive control(FCS-MPC),sensorless control,and fault tolerant control(FTC).The corresponding control principles,control targets,fundamental approaches,advanced approaches,methodologies,merits and shortcomings are revealed and analyzed in detail.
文摘Air-gap magnetic field modulation has been widely observed in electric machines.In this study,we present an analytical analysis and performance characterization of brushless doubly fed induction machines(BDFIMs)fed by two independent converters from the perspective of air-gap field modulation.The spiral-loop winding is studied in detail as an example to show the generalized workflow that can also be used to analyze other short-circuited rotor winding types,such as nested-loop and multiphase double-layer windings.Magnetic field conversion factors are introduced to characterize the modulation behavior of special rotor windings and facilitate their comparison in terms of cross-coupling capability,average torque,and harmonic content of the air-gap flux density waveforms.The stator magnetomotive force(MMF),rotor MMF,and resultant air-gap MMF are considered,based on which the closed-form inductance formulas are derived,and the torque equation is obtained along with the optimal current angle for maximum torque operation by using the virtual work principle.The design equations are then developed for the initial sizing and geometry scaling of the BDFIMs.Transient finite element analysis and experimental measurements are performed to validate the analysis.
基金supported by the Natural Scienceof Shandong Province,China(ZR2019MEE033)。
文摘The characteristics of the packing material under an alternating electric field are an important factor in the removal of FCCS particles.In this study,the electric field distribution of a separation unit consisting of packed spheres under an alternating electric field is simulated,and the movement mechanism of catalyst particles is analysed.An"effective contact point"model is derived to predict the adsorption of filler contact points on catalyst particles under the alternating electric field,and the model is validated by simulations and experiments.The numerical calculation and experimental results indicate that the electrical properties of the filler spheres,the filler angleθ,and the frequency f of the alternating electric field affect the adsorption of catalyst particles.As the frequency of the electric field increases,the particle removal efficiency of the high-conductivity filler(silicon carbide)increases and then settles,and the separation efficiency of the low-conductivity filler(glass,zirconia)is not sensitive to the change in electric field frequency.
基金supported by the Natural Science Foundation of China under Grant U22A20214 and Grant 51837010。
文摘A versatile analytical method(VAM) for calculating the harmonic components of the magnetomotive force(MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method has been established in early literature. However, its practical applications and significance in advancing the analysis of AC machines need further elaboration. This paper aims to complement VAM by augmenting its theory, offering additional insights into its conclusions, as well as demonstrating its utility in assessing armature windings and its application of calculating torque for permanent magnet synchronous machines(PMSM). This work contributes to advancing the analysis of AC machines and underscores the potential for improved design and performance optimization.
