电流互感器具有响应快、精度高和频带宽等显著优势,在电力系统中广泛用于电流信号的在线监测。电流互感器应用于高压直流输电换流阀晶闸管级在线监测电路时,因长期运行在大电流、强电磁环境等条件下,其输出信号易受到多种噪声干扰的影响...电流互感器具有响应快、精度高和频带宽等显著优势,在电力系统中广泛用于电流信号的在线监测。电流互感器应用于高压直流输电换流阀晶闸管级在线监测电路时,因长期运行在大电流、强电磁环境等条件下,其输出信号易受到多种噪声干扰的影响,导致信噪比显著下降、电流监测的准确性和可靠性降低。为解决这一问题,提出了一种基于频域自适应滤波最小化均方误差(least mean square,LMS)算法的信号优化方法,针对实际使用场景的技术要求并结合频域自适应滤波原理分析,得到了变步长LMS算法最优参数,并成功应用于晶闸管级监测电路的电流互感器输出信号优化。针对电流互感器输出信号开展实验验证,结果表明所提方法相较于小波变换方法,信噪比提高了15%,算法收敛速度提升了25%,显著优化了互感器在线监测性能,有效解决了换流阀晶闸管电流信号实时准确监测难题。展开更多
Schwarz methods are an important type of domain decomposition methods. Using the Fourier transform, we derive error propagation matrices and their spectral radii of the classical Schwarz alternating method and the add...Schwarz methods are an important type of domain decomposition methods. Using the Fourier transform, we derive error propagation matrices and their spectral radii of the classical Schwarz alternating method and the additive Schwarz method for the biharmonic equation in this paper. We prove the convergence of the Schwarz methods from a new point of view, and provide detailed information about the convergence speeds and their dependence on the overlapping size of subdomains. The obtained results are independent of any unknown constant and discretization method, showing that the Schwarz alternating method converges twice as quickly as the additive Schwarz method.展开更多
文摘电流互感器具有响应快、精度高和频带宽等显著优势,在电力系统中广泛用于电流信号的在线监测。电流互感器应用于高压直流输电换流阀晶闸管级在线监测电路时,因长期运行在大电流、强电磁环境等条件下,其输出信号易受到多种噪声干扰的影响,导致信噪比显著下降、电流监测的准确性和可靠性降低。为解决这一问题,提出了一种基于频域自适应滤波最小化均方误差(least mean square,LMS)算法的信号优化方法,针对实际使用场景的技术要求并结合频域自适应滤波原理分析,得到了变步长LMS算法最优参数,并成功应用于晶闸管级监测电路的电流互感器输出信号优化。针对电流互感器输出信号开展实验验证,结果表明所提方法相较于小波变换方法,信噪比提高了15%,算法收敛速度提升了25%,显著优化了互感器在线监测性能,有效解决了换流阀晶闸管电流信号实时准确监测难题。
基金supported by the National Natural Science Foundation of China (No. 10671154)the Na-tional Basic Research Program (No. 2005CB321703)the Science and Technology Foundation of Guizhou Province of China (No. [2008]2123)
文摘Schwarz methods are an important type of domain decomposition methods. Using the Fourier transform, we derive error propagation matrices and their spectral radii of the classical Schwarz alternating method and the additive Schwarz method for the biharmonic equation in this paper. We prove the convergence of the Schwarz methods from a new point of view, and provide detailed information about the convergence speeds and their dependence on the overlapping size of subdomains. The obtained results are independent of any unknown constant and discretization method, showing that the Schwarz alternating method converges twice as quickly as the additive Schwarz method.
