Abstract Accurate forecast of future container throughput of a port is very important for its con struction, upgrading, and operation management. This study proposes a transfer forecasting model guided by discrete par...Abstract Accurate forecast of future container throughput of a port is very important for its con struction, upgrading, and operation management. This study proposes a transfer forecasting model guided by discrete particle swarm optimization algorithm （TF-DPSO）. It firstly transfers some related time series in source domain to assist in modeling the target time series by transfer learning technique, and then constructs the forecasting model by a pattern matching method called analog complexing. Finally, the discrete particle swarm optimization algorithm is introduced to find the optimal match between the two important parameters in TF-DPSO. The container throughput time series of two im portant ports in China, Shanghai Port and Ningbo Port are used for empirical analysis, and the results show the effectiveness of the proposed model.展开更多
Accurate,high bandwidth current control is a requirement for high performance vector controlled AC drives.Synchronous PI current regulators are the preferred solution for this purpose.Design and operation principles o...Accurate,high bandwidth current control is a requirement for high performance vector controlled AC drives.Synchronous PI current regulators are the preferred solution for this purpose.Design and operation principles of synchronous PI current regulators are well established.However,there are a number of issues that must be considered,especially when the drive must operate at high synchronous frequencies,including regulator design,effects due to discretization and the associated delays,voltage constraints and current sampling issues among other.Inadmissible degradation of the current regulator performance and consequently of the drive can occur otherwise.展开更多
文摘模块化多电平换流器(modular multilevel converter,MMC)具有运行稳定、控制多样化等优点,对其精确建模成为当前研究热点。提出了一种基于复矢量的MMC交直流侧阻抗建模方法。该方法根据复矢量建模的基本原理分析了换流器的正负序转换关系,并在考虑三相耦合的前提下,从差共模角度简述了三相MMC的建模要点,建立了三相系统的完整时域模型。引入谐波状态空间理论(harmonic state space,HSS)对所建模型进行处理来提高建模精度,并利用接口矩阵及阻抗求解的基本原理建立了MMC的交直流侧阻抗模型。最后在仿真平台进行了对比实验,证实了建模方法的可行性。
基金partly supported by the Natural Science Foundation of China under Grant Nos.71101100 and 70731160635New Teachers’Fund for Doctor Stations,Ministry of Education under Grant No.20110181120047+5 种基金Excellent Youth Fund of Sichuan University under Grant No.2013SCU04A08China Postdoctoral Science Foundation under Grant Nos.2011M500418,2012T50148 and 2013M530753Frontier and Cross-innovation Foundation of Sichuan University under Grant No.skqy201352Soft Science Foundation of Sichuan Province under Grant No.2013ZR0016Humanities and Social Sciences Youth Foundation of the Ministry of Education of China under Grant No.11YJC870028Selfdetermined Research Funds of CCNU from the Colleges’ Basic Research and Operation of MOE under Grant No.CCNU13F030
文摘Abstract Accurate forecast of future container throughput of a port is very important for its con struction, upgrading, and operation management. This study proposes a transfer forecasting model guided by discrete particle swarm optimization algorithm （TF-DPSO）. It firstly transfers some related time series in source domain to assist in modeling the target time series by transfer learning technique, and then constructs the forecasting model by a pattern matching method called analog complexing. Finally, the discrete particle swarm optimization algorithm is introduced to find the optimal match between the two important parameters in TF-DPSO. The container throughput time series of two im portant ports in China, Shanghai Port and Ningbo Port are used for empirical analysis, and the results show the effectiveness of the proposed model.
文摘Accurate,high bandwidth current control is a requirement for high performance vector controlled AC drives.Synchronous PI current regulators are the preferred solution for this purpose.Design and operation principles of synchronous PI current regulators are well established.However,there are a number of issues that must be considered,especially when the drive must operate at high synchronous frequencies,including regulator design,effects due to discretization and the associated delays,voltage constraints and current sampling issues among other.Inadmissible degradation of the current regulator performance and consequently of the drive can occur otherwise.
