Abstract. After defined the basic concept of mode or intrinsic mode, EMD as a data-driven adaptive decomposition method, its purpose is to decompose arbitrary non-stationary and nonlinear signal into different intrinsic mode functions (IMFs) on the time series. However, in some cases, the EMD method often cannot get ideal decomposition results which can result mode mixing problem. once mode mixing phenomenon appear, mode mixing will affect the subsequent decomposition components, the time-frequency distribution of subsequent IMFs are confusion, eventually the EMD decomposition process lose physical meaning. The EMD mode mixing problem directly affect its application in various fields. This paper discuss the basic cause of mode mixing, the results show that: the jumping change of the decomposed signal result in mode mixing, mode mixing caused by amplitude and frequency relationship of the signal.

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This paper proposes the dual-terminal positioning method of using ground potential traveling waves to locate the fault location of transmission lines. The traveling wave monitoring terminal is installed at the ground potential end. Installation and maintenance do not need to cooperate with the power outage plan, which can effectively solve the problem of inconvenient maintenance toward the distributed fault diagnosis system. Overhead transmission lines with 110 kV and higher voltage generally have ground lines. When a lightning strike or ground fault happens, not only will a fault traveling wave be generated on the line but also a fault traveling wave will be generated at the ground potential end and propagate along the tower. As the traveling wave current propagating along the ground potential can be effectively detected, the double-ended positioning of the ground potential can be realized. The application in the actual grid shows that a distributed monitoring system on the line tower and the ground line can quickly and accurately determine the fault location.

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