Fault Section identification method for Multi-terminal Hybrid HVDC Lines

For multi-terminal hybrid HVDC transmission system, the identification of DC line fault section is of great significance to isolate the fault. This paper analyses the current polarity characteristics of faults located on different fault section of DC lines based on equivalent line model firstly. Then, aiming at the characteristic drawn from the analysis, which medium and low frequency current energy will be reduced by T zone, a fault section identification method based on high frequency transient current polarity by wavelet transform is proposed. Finally, simulations in PSCAD/EMTDC verify the effectiveness and sensitivity of proposed fault section identification method.