基于频域辨识的合并单元额定延时测量技术

Rate delay time measuring technology of merging unit based on frequency domain identification

智能变电站中合并单元数据采集和输出过程存在着固有的额定延时,此延时直接影响继电保护的动作时间。目前,额定延时测量方法存在着不足,给系统安全运行埋下了安全隐患。文中从合并单元采样环节的构成出发,分析其采样、处理过程中额定延时的群延迟特性和传变延迟。研究表明:时域中的群延迟在频域中相频特性应为线性相位,据此提出通过输入不同频率的信号以获得合并单元的相频特性曲线、进而辨识出额定延时的频域识别测量技术,并分析合并单元的相位误差对此额定延时测量方法的影响,最后通过理论仿真验证了此额定延时测量技术的可行性和正确性。文中所提方法为合并单元数字化采样延时测量的工程应用提供了一种切实可行的延时测量技术,能够确保继电保护系统的正确、可靠运行。

There is rated delay time in data sampling and outputting process of merging unit(MU)in smart substation,which directly relates with the time of relay protection.Currently,there is shortage in rated delay time measuring and threatens the normal system operation.In this paper,the group and transfer delay time are analyzed in the sampling,processing link of MU starting from sampling link.The research results show that the group delay time in time domain corresponds to linear phase characteristics in frequency domain.On this basis,the rated delay time measuring method based on frequency domain identification is proposed by inputting different frequency signals and obtaining phase frequency characteristics of MU.Meanwhile,the influences of MU phase error on the measuring of rated delay time are analyzed.Finally,the feasibility and validity of rated delay time method are verified by theoretical simulation and experiment measurement.The method in this paper provides a feasible way to measure delay time in digital sampling engineering application,and ensures the validity and reliability of relay protection.