Compressional harmonic wave propagation from a cylindrical tunnel or borehole in an intact rock is the basis for investigation of the practical explosion waves in a fractured rock mass. The amplitudes of the radial st...Compressional harmonic wave propagation from a cylindrical tunnel or borehole in an intact rock is the basis for investigation of the practical explosion waves in a fractured rock mass. The amplitudes of the radial stress wave obtained from the universal distinct element code (UDEC) were compared with the analytical solutions for two cases with different conditions. Good agreements between the UDEC results and the analytical solutions have been achieved. It indicates that UDEC can model 2-D dynamic problems at a high degree of accuracy.展开更多
The paper deals with analysis and synthesis of non-harmonic and non-linear sources and appliances, and their interaction with harmonic power supply network. Basic idea is based on knowledge of harmonic spectrum of the...The paper deals with analysis and synthesis of non-harmonic and non-linear sources and appliances, and their interaction with harmonic power supply network. Basic idea is based on knowledge of harmonic spectrum of the sources and/or appliances, respectively. Obviously, one need to know voltage harmonic components of voltage sources (renewable with inverters,...), and current harmonic components generated by non-linear appliances (rectifiers,...). Method of investigation lies on decomposition of real electric circuit into n-harmonic separated equivalent schemes for each harmonic component. Then transient analysis will be done for each scheme separately using "impedance harmonic matrices". The important fact is that each equivalent scheme is now linearized and therefore easily calculated. Finally, the effects of each investigated schemes arc summed into resulting quantities of real non-linear electric circuit.展开更多
A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous...A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.展开更多
This paper aims to present a new point of view about the active power measurement, for billing purposes, measured at the PCC (point of common coupling) between the utility and the consumer when harmonic distortions ...This paper aims to present a new point of view about the active power measurement, for billing purposes, measured at the PCC (point of common coupling) between the utility and the consumer when harmonic distortions are involved. Depending on theorigin of it, the active power can result in higher or lower values in comparison to the fundamental component. The consequences are higher costs for the consumer or losses for the electric utility. Using computational simulations and theoretical analysis, these aspects are evaluated and compared.展开更多
We theoretically study the high-order harmonic generation (HHG) from a hydrogen atom in an intense few-cycle chirped fundamental laser in combination with an ultraviolet (uv) controlling pulse. The high-order harm...We theoretically study the high-order harmonic generation (HHG) from a hydrogen atom in an intense few-cycle chirped fundamental laser in combination with an ultraviolet (uv) controlling pulse. The high-order harmonic spectrum is calculated by solving the time-dependent Schr6dinger equation using the split-operator method. In our calculation, we present the difference of the high-order harmonic spectrum from one-dimensional (1D) model hydrogen atom and three-dimensional (3D) real hydrogen atom. We found that the plateau of the high-order harmonic generation from the 1D ease and 3D case are all extended effectively to Iv -k 35Up due to the presence of the chirped laser pulse and the HHG supercontinuum spectrum is generated by adding an ultraviolet controlling pulse at a proper time, but the efficiency of the HHC for 3D case is more higher at the near cut-off region than the 1D case. Therefore, the generation of the attosecond pulse by synthesizing the harmonics near cut-off region have some slight differences between 1D and 3D simulations. As a real 3D case study, we show that an isolated 18 as pulse with a bandwidth of 232.5 eV is generated directly by optmizing the combination laser fields.展开更多
基金Projects 50278057 supported by National Natural Science Foundation of China and 2002CB412703 supported by 973 Project
文摘Compressional harmonic wave propagation from a cylindrical tunnel or borehole in an intact rock is the basis for investigation of the practical explosion waves in a fractured rock mass. The amplitudes of the radial stress wave obtained from the universal distinct element code (UDEC) were compared with the analytical solutions for two cases with different conditions. Good agreements between the UDEC results and the analytical solutions have been achieved. It indicates that UDEC can model 2-D dynamic problems at a high degree of accuracy.
文摘The paper deals with analysis and synthesis of non-harmonic and non-linear sources and appliances, and their interaction with harmonic power supply network. Basic idea is based on knowledge of harmonic spectrum of the sources and/or appliances, respectively. Obviously, one need to know voltage harmonic components of voltage sources (renewable with inverters,...), and current harmonic components generated by non-linear appliances (rectifiers,...). Method of investigation lies on decomposition of real electric circuit into n-harmonic separated equivalent schemes for each harmonic component. Then transient analysis will be done for each scheme separately using "impedance harmonic matrices". The important fact is that each equivalent scheme is now linearized and therefore easily calculated. Finally, the effects of each investigated schemes arc summed into resulting quantities of real non-linear electric circuit.
基金Project(JC200903180555A) supported by Shenzhen City Science and Technology Plan, China
文摘A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.
文摘This paper aims to present a new point of view about the active power measurement, for billing purposes, measured at the PCC (point of common coupling) between the utility and the consumer when harmonic distortions are involved. Depending on theorigin of it, the active power can result in higher or lower values in comparison to the fundamental component. The consequences are higher costs for the consumer or losses for the electric utility. Using computational simulations and theoretical analysis, these aspects are evaluated and compared.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 11044007 and 11047016the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20096203110001+1 种基金the Young Teachers Foundation of Northwest Normal University under Grant No. NWNU-LKQN-10-5Foundation of North west Normal University under Grant No. NWNU-KJCXGC-03-62
文摘We theoretically study the high-order harmonic generation (HHG) from a hydrogen atom in an intense few-cycle chirped fundamental laser in combination with an ultraviolet (uv) controlling pulse. The high-order harmonic spectrum is calculated by solving the time-dependent Schr6dinger equation using the split-operator method. In our calculation, we present the difference of the high-order harmonic spectrum from one-dimensional (1D) model hydrogen atom and three-dimensional (3D) real hydrogen atom. We found that the plateau of the high-order harmonic generation from the 1D ease and 3D case are all extended effectively to Iv -k 35Up due to the presence of the chirped laser pulse and the HHG supercontinuum spectrum is generated by adding an ultraviolet controlling pulse at a proper time, but the efficiency of the HHC for 3D case is more higher at the near cut-off region than the 1D case. Therefore, the generation of the attosecond pulse by synthesizing the harmonics near cut-off region have some slight differences between 1D and 3D simulations. As a real 3D case study, we show that an isolated 18 as pulse with a bandwidth of 232.5 eV is generated directly by optmizing the combination laser fields.