基于希尔伯特–黄变换的超高速方向保护研究

希尔伯特-黄变换(Hilber-Huang transform，HHT)是一种分析非平稳信号的有效方法。作者提出一种新的以HHT为基础的超高速方向保护方案，利用HHT来提取线路故障后的正、反向行波信息，通过对行波信号进行经验模态分解求出其高频部分(即第一个固有模态函数)，然后对固有模态函数进行Hilbert变换求取幅值，并利用幅值比较的方式来判断故障的时刻和方向。该方案克服了应用小波提取暂态故障信息时受到母函数选择限制的缺点。仿真结果证明了该方案的可行性和有效性，同时表明故障距离、接地电阻和故障初始角等因素对该方案影响很小

Study of Ultra-High-Speed Directional Protection of Transmission Lines Based on Hilbert-Huang Transform

Hilbert-Huang transform(HHT) is a valid means of analyzing non-stationary signals.The authors propose a new ultra-high speed directional protection scheme in which HHT is used to extract the information of post-fault forward and reverse traveling waves.Through empirical mode decomposition(EMD),the first intrinsic mode function(IMF) of traveling waves,i.e.,the high frequency part of fault information,is separated out;then by means of Hilbert transform of the IMF,the magnitude is solved;comparing the magnitude of Hilbert amplitude spectrum for a period of time after faults occur,the fault direction can be identified.The proposed scheme can overcome the defect that when wavelet transform is used to extract transient fault information,wavelet transform itself is restricted by the selection of mother wavelet.Simulation results show that the proposed scheme is feasible and effective,at the same time;it is also shown that the proposed scheme is not affected by fault distance,grounding resistance and low fault inception angle.