This paper is concerned with the discretization of the fractional-order differentiator and integrator, which is the foundation of the digital realization of fractional order controller. Firstly, the parameterized Al-A...This paper is concerned with the discretization of the fractional-order differentiator and integrator, which is the foundation of the digital realization of fractional order controller. Firstly, the parameterized Al-Alaoui transform is presented as a general generating function with one variable parameter, which can be adjusted to obtain the commonly used generating functions (e.g. Euler operator, Tustin operator and Al-Alaoui operator). However, the following simulation results show that the optimal variable parameters are different for different fractional orders. Then the weighted square integral index about the magtitude and phase is defined as the objective functions to achieve the optimal variable parameter for different fractional orders. Finally, the simulation results demonstrate that there are great differences on the optimal variable parameter for differential and integral operators with different fractional orders, which should be attracting more attentions in the design of digital fractional order controller.展开更多
The characteristics of conducted disturbances via current transformer(CT)caused by switch operations in 1000 kV UHV substations are studied in this paper.Since the broadband circuit models might have limitations on th...The characteristics of conducted disturbances via current transformer(CT)caused by switch operations in 1000 kV UHV substations are studied in this paper.Since the broadband circuit models might have limitations on the stability and accuracy for CT conducted disturbance simulation,a frequencydomain simulation method without circuit synthesis is proposed based on VFTC spectrum and CT transfer characteristics.To improve VFTC simulation accuracy,both the bushing radiation loss and frequency-dependent earth impedance are taken into consideration.Transfer characteristics of three types of windings for the 1000 kV GIS CT are ingeniously measured from a combination of fast and slow impulse tests.Through conducted disturbances simulations in UHV Wuhu substation,bushing radiation loss is found to have a suppression effect on the highfrequency response but the effect of frequency-dependent earth impedance can be ignored.As a result,the maximum amplitude of 84.5 A for the conducted disturbance is obtained,thus a fast damped oscillatory wave immunity test with no lower than Level 4 from IEC standard is suggested to test the anti-interference performance of the secondary equipment in UHV substation.展开更多
文摘This paper is concerned with the discretization of the fractional-order differentiator and integrator, which is the foundation of the digital realization of fractional order controller. Firstly, the parameterized Al-Alaoui transform is presented as a general generating function with one variable parameter, which can be adjusted to obtain the commonly used generating functions (e.g. Euler operator, Tustin operator and Al-Alaoui operator). However, the following simulation results show that the optimal variable parameters are different for different fractional orders. Then the weighted square integral index about the magtitude and phase is defined as the objective functions to achieve the optimal variable parameter for different fractional orders. Finally, the simulation results demonstrate that there are great differences on the optimal variable parameter for differential and integral operators with different fractional orders, which should be attracting more attentions in the design of digital fractional order controller.
基金supported by the National Natural Science Foundation of China(51977199).
文摘The characteristics of conducted disturbances via current transformer(CT)caused by switch operations in 1000 kV UHV substations are studied in this paper.Since the broadband circuit models might have limitations on the stability and accuracy for CT conducted disturbance simulation,a frequencydomain simulation method without circuit synthesis is proposed based on VFTC spectrum and CT transfer characteristics.To improve VFTC simulation accuracy,both the bushing radiation loss and frequency-dependent earth impedance are taken into consideration.Transfer characteristics of three types of windings for the 1000 kV GIS CT are ingeniously measured from a combination of fast and slow impulse tests.Through conducted disturbances simulations in UHV Wuhu substation,bushing radiation loss is found to have a suppression effect on the highfrequency response but the effect of frequency-dependent earth impedance can be ignored.As a result,the maximum amplitude of 84.5 A for the conducted disturbance is obtained,thus a fast damped oscillatory wave immunity test with no lower than Level 4 from IEC standard is suggested to test the anti-interference performance of the secondary equipment in UHV substation.
