A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems.This paper analyzes the accuracy of the half-power bandwidth m...A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems.This paper analyzes the accuracy of the half-power bandwidth method with the third-order correction in damping estimation for multi-DOF linear systems.Damping ratios in a two-DOF linear system are estimated using its displacement and acceleration frequency response curves,respectively.A wide range of important parameters that characterize the shape of these response curves are taken into account.Results show that the third-order correction may greatly improve the accuracy of the half-power bandwidth method in estimating damping in a two-DOF system.In spite of this,the half-power bandwidth method may significantly overestimate the damping ratios of two-DOF systems in some cases.展开更多
A new dispersive relation is found and a half-power tracc formulas for the generalized Jaulent-Miodek equation under the decaying conditions at infinity are obtained.
随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage sys...随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage system,MMC-BESS)虽然在交直流互联的同时,实现了储能的功能,但电池中流过的工频、二倍频等脉动电流成分对电池寿命有潜在影响,且传统的模块化多电平(modular multilevel converter,MMC)换流站的改造成本高。本工作提出的直流直挂储能装置将换流和储能分离,电池电流仅为直流和高频脉动成分,工况对电池友好,且直流直挂储能系统需要电池单体数量仅为MMC-BESS的1/6,成本低。对直流直挂储能装置的拓扑结构及工作原理进行分析;对级联子模块的数量和参数进行设计;基于载波移相调制,推导直流纹波电流,进而对并网电感参数进行设计;建立直流直挂储能装置的数学模型,推导控制模型,根据控制框图进行功率控制。最后,通过仿真和样机实验,验证该半桥拓扑级联型直流直挂储能装置设计的可行性及正确性。实验证明,该设计和控制方法效果良好,对高压大容量直流直挂储能装置的设计有一定参考价值。展开更多
基金National Natural Science Foundation under Grant No. 51179093National Basic Research Program of China under Grant No. 2011CB013602Program for New Century Excellent Talents in University under Grant No.NCET-10-0531
文摘A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems.This paper analyzes the accuracy of the half-power bandwidth method with the third-order correction in damping estimation for multi-DOF linear systems.Damping ratios in a two-DOF linear system are estimated using its displacement and acceleration frequency response curves,respectively.A wide range of important parameters that characterize the shape of these response curves are taken into account.Results show that the third-order correction may greatly improve the accuracy of the half-power bandwidth method in estimating damping in a two-DOF system.In spite of this,the half-power bandwidth method may significantly overestimate the damping ratios of two-DOF systems in some cases.
文摘A new dispersive relation is found and a half-power tracc formulas for the generalized Jaulent-Miodek equation under the decaying conditions at infinity are obtained.
文摘随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage system,MMC-BESS)虽然在交直流互联的同时,实现了储能的功能,但电池中流过的工频、二倍频等脉动电流成分对电池寿命有潜在影响,且传统的模块化多电平(modular multilevel converter,MMC)换流站的改造成本高。本工作提出的直流直挂储能装置将换流和储能分离,电池电流仅为直流和高频脉动成分,工况对电池友好,且直流直挂储能系统需要电池单体数量仅为MMC-BESS的1/6,成本低。对直流直挂储能装置的拓扑结构及工作原理进行分析;对级联子模块的数量和参数进行设计;基于载波移相调制,推导直流纹波电流,进而对并网电感参数进行设计;建立直流直挂储能装置的数学模型,推导控制模型,根据控制框图进行功率控制。最后,通过仿真和样机实验,验证该半桥拓扑级联型直流直挂储能装置设计的可行性及正确性。实验证明,该设计和控制方法效果良好,对高压大容量直流直挂储能装置的设计有一定参考价值。