This paper presents the results from laboratory experiments and theoretical analysis to investigate the development of scour around submarine pipeline under steady current conditions. Experiments show that the scour p...This paper presents the results from laboratory experiments and theoretical analysis to investigate the development of scour around submarine pipeline under steady current conditions. Experiments show that the scour process takes place in two stages: the initial rapid scour and the subsequent gradual scour development stage. An empirical formula for calculating the equilibrium scour depth(the maximum scour depth) is developed by using the regression method. This formula together with the maximum entropy theory can be applied to establish a formula to predict the scour process for given water depth, diameter of pipeline and flow velocity. Good agreement between the predicted and measured scour depth is obtained.展开更多
A fully hardware-implemented phase calculating system for the feedback control in the lower-hybrid current drive （LHCD） experiments is presented in this paper. By taking advantages of field programmable gate array ...A fully hardware-implemented phase calculating system for the feedback control in the lower-hybrid current drive （LHCD） experiments is presented in this paper. By taking advantages of field programmable gate array （FPGA） chips with embedded digital signal processing （DSP） cores and the Matlab-aided design method, the phase calculating algorithm with a square root operation and parallel process are efficiently implemented in a single FPGA chip to complete the calculation of phase differences fast and accurately in the lower-hybrid wave （LHW） system on EAST.展开更多
多相永磁同步电机驱动系统在低压大功率、高可靠性的应用场合日受青睐和瞩目。首先研究了适用于五相永磁同步电机系统的传统有限集模型预测转矩控制(finite-control-set model predictive torque control,FCS-MPTC)算法,为了消除d3-q3...多相永磁同步电机驱动系统在低压大功率、高可靠性的应用场合日受青睐和瞩目。首先研究了适用于五相永磁同步电机系统的传统有限集模型预测转矩控制(finite-control-set model predictive torque control,FCS-MPTC)算法,为了消除d3-q3谐波子空间的低次电流谐波,构造了包含谐波项的目标函数。然后,为了减小FCS-MPTC算法实现时带来的巨大计算量,提出了一种基于转矩与磁链无差拍估算的每个控制周期内电压矢量控制集优化方法。所提算法不仅保持了传统FCS-MPTC算法优越的稳态性能、快速的动态响应和低次电流谐波抑制能力,同时显著减少了数字实现的运算量。最后,将所提算法分别与两种传统FCS-MPTC算法进行半实物实验对比分析,验证了所提算法的正确性和有效性。展开更多
The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were pr...The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems.At first,novel generating mechanisms of zero-sequence voltage and residual current were proposed.Then the compositions of residue parameters,including residual current and residual admittances,were decomposed in detail.After that,an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed,and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection.Furthermore,the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder,which cannot be affected by the asymmetry of the network.Theoretical analysis and the MATALB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms.展开更多
基金financially supported by the National Nature Science Foundation of China (Grant No. 51279189)
文摘This paper presents the results from laboratory experiments and theoretical analysis to investigate the development of scour around submarine pipeline under steady current conditions. Experiments show that the scour process takes place in two stages: the initial rapid scour and the subsequent gradual scour development stage. An empirical formula for calculating the equilibrium scour depth(the maximum scour depth) is developed by using the regression method. This formula together with the maximum entropy theory can be applied to establish a formula to predict the scour process for given water depth, diameter of pipeline and flow velocity. Good agreement between the predicted and measured scour depth is obtained.
文摘A fully hardware-implemented phase calculating system for the feedback control in the lower-hybrid current drive （LHCD） experiments is presented in this paper. By taking advantages of field programmable gate array （FPGA） chips with embedded digital signal processing （DSP） cores and the Matlab-aided design method, the phase calculating algorithm with a square root operation and parallel process are efficiently implemented in a single FPGA chip to complete the calculation of phase differences fast and accurately in the lower-hybrid wave （LHW） system on EAST.
文摘多相永磁同步电机驱动系统在低压大功率、高可靠性的应用场合日受青睐和瞩目。首先研究了适用于五相永磁同步电机系统的传统有限集模型预测转矩控制(finite-control-set model predictive torque control,FCS-MPTC)算法,为了消除d3-q3谐波子空间的低次电流谐波,构造了包含谐波项的目标函数。然后,为了减小FCS-MPTC算法实现时带来的巨大计算量,提出了一种基于转矩与磁链无差拍估算的每个控制周期内电压矢量控制集优化方法。所提算法不仅保持了传统FCS-MPTC算法优越的稳态性能、快速的动态响应和低次电流谐波抑制能力,同时显著减少了数字实现的运算量。最后,将所提算法分别与两种传统FCS-MPTC算法进行半实物实验对比分析,验证了所提算法的正确性和有效性。
基金This work was supported in part by the National Natural Science Foundation of China(No.51177039)in part by the Fundamental Research Funds for the Central Universities(2018B06314)the 111 Intelligence project(B14022).
文摘The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems.At first,novel generating mechanisms of zero-sequence voltage and residual current were proposed.Then the compositions of residue parameters,including residual current and residual admittances,were decomposed in detail.After that,an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed,and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection.Furthermore,the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder,which cannot be affected by the asymmetry of the network.Theoretical analysis and the MATALB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms.
