The Identification of Internal and External Faults for ±800kV UHVDC Transmission Line Based on Using Wavelet Based Multi-Resolution Analysis

There is a smoothing reactor and DC filter between the inverter and the direct current line to form a boundary in the HVDC transmission system.Since this boundary presents the stop-band characteristic to the high frequency transient voltage signals,the high-frequency transient voltage signal caused by external faults through boundary will be attenuated and the signals caused by internal faults will be unchanged.The wavelet analysis can be used as a tool to extract the feature of the fault to classify the internal fault and the external fault in HVDC transmission system.This paper explores the new method of wavelet based Multi-Resolution Analysis for signal decomposition to classify the difference types fault.