Fault identification method for flexible HVDC line based on Euclidean similarity calculation

To solve the problems of insufficient ability to withstand transition resistance of existing travelling wave (TW) protection, a fault identification method for flexible HVDC transmission line based on Euclidean similarity calculation is proposed. Through detailed analysis of the 1 -mode voltage backwards TW, it can be concluded that the current-limiting reactor (CLR) will affect the variation characteristics of initial travelling wave (ITW). Therefore, this paper takes the change rate waveforms of line-mode voltage ITW of typical internal and external faults as the reference waveforms, and calculates the Euclidean similarity between the fault waveform and the reference waveforms to identify faults, and reduces the influence of transition resistance with the help of normalization. The principle of the method is simple, and the simulation results show that the proposed method can reliably identify the faults, with high sensitivity and selectivity.