针对目前电力系统低频振荡模式识别和参数提取中的噪声干扰等问题,提出一种基于希尔伯特变换(Hilbert transformation,HT)和能量函数经验模态分解(energy function of empirical mode decomposition,EFEMD)相结合的低频振荡模态辨识方...针对目前电力系统低频振荡模式识别和参数提取中的噪声干扰等问题,提出一种基于希尔伯特变换(Hilbert transformation,HT)和能量函数经验模态分解(energy function of empirical mode decomposition,EFEMD)相结合的低频振荡模态辨识方法。首先运用经验模态分解(empirical mode decomposition,EMD)对含有噪声的电力系统低频振荡广域测量信号进行经验模态分解得到各个固有模态函数(intrinsic modal function,IMF),随后应用EFEMD-HT能量法对IMF进行能量计算并权重,筛选出系统的主导振荡模式,最后通过Hilbert变换对主导振荡模式进行参数的提取。通过对理想信号、EPRI-36机系统仿真信号以及电网实测PMU信号的仿真验证了所提EFEMD-HT能量法的可行性与有效性,能够对系统的主导振荡模式进行准确地辨识。展开更多
A low-energy ion spectrometer(LEIS) for use aboard three-axis stabilized spacecraft has been developed to measure ion energy per charge distribution in three-dimensional space with good energy-, angular-and temporal-r...A low-energy ion spectrometer(LEIS) for use aboard three-axis stabilized spacecraft has been developed to measure ion energy per charge distribution in three-dimensional space with good energy-, angular-and temporal-resolutions. For the standard top-hat electrostatic analyzer used widely in space plasma detection, three-axis stabilized spacecraft makes it difficult to obtain complete coverage of all possible ion arrival directions. We have designed angular scanning deflectors supplementing to a cylindrically symmetric top-hat electrostatic analyzer to provide a half-space field of view as 360°×90°(–45°–+45°), and fabricated the LEIS flight model for detecting magnetospheric ions in geosynchronous orbit. The performance of this payload has been evaluated in detail by a series of simulation and environmental tests, and the payload has also been calibrated through laboratory experiments using a low-energy ion source. The results show that capabilities of the LEIS payload are in accordance with the requirements of a magnetospheric mission.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41327802)the CAS Key Research Program of Frontier Sciences(Grant No.QYZDB-SSW-DQC015)
文摘A low-energy ion spectrometer(LEIS) for use aboard three-axis stabilized spacecraft has been developed to measure ion energy per charge distribution in three-dimensional space with good energy-, angular-and temporal-resolutions. For the standard top-hat electrostatic analyzer used widely in space plasma detection, three-axis stabilized spacecraft makes it difficult to obtain complete coverage of all possible ion arrival directions. We have designed angular scanning deflectors supplementing to a cylindrically symmetric top-hat electrostatic analyzer to provide a half-space field of view as 360°×90°(–45°–+45°), and fabricated the LEIS flight model for detecting magnetospheric ions in geosynchronous orbit. The performance of this payload has been evaluated in detail by a series of simulation and environmental tests, and the payload has also been calibrated through laboratory experiments using a low-energy ion source. The results show that capabilities of the LEIS payload are in accordance with the requirements of a magnetospheric mission.
