Spectrum analysis method of residual current based on Hilbert-Huang transform

For the development of residual current protection device in low voltage network, aiming at complexity and uncertainty of residual current spectrum in the transient process of biological electric shock faults, the Hilbert-Huang transform is applied to analyze spectrum characteristics of each intrinsic mode function (IMF) component in residual current and determine the distribution of each IMF at different time and frequency. Based on Hilbert — Huang transform, a method for characterizing the effective information of residual current signal performance is proposed. The study results show that the effective frequency in residual current is mainly below 1 KHZ and the correlation of low-frequency IMF component amplitude can be up to 0.99 above which can provide theoretical basis and technical support for the development of residual current protective device acting based on branch current signal when the human body electric shock occurs.