| It is of great importance to locate the fault position precisely after HVDC transmission line faults for fast power recovery and similar faults prevention. Travelling wave fault location (TWFL) plays a significant role in this task, the accuracy of which depends mainly on the accuracy of wavefront detection and the choice of travelling wave speed.The TWFL methods that used now in engineering practice often exhibit low accuracy and bad adaptation ability to different fault conditions in different operating modes. To provide a remedy for the problem, the wavefront and wave speed characteristics are deeply analyzed in the paper, and a novel TWFL algorithm is proposed.Firstly, it is observed how travelling wave speed varies with fault distance, the bandwith of the wave, sampling rate, et.al, and how the variant speed effects the accuracy of fault location is also analyzed. Then, a processing method to the wave speed is addressed, which can adapt well to the present hardware performance. To pinpoint the wavefront, the waveform properties of the fault travelling waves are deeply analyzed in the text. Wavelet transform (WT) theory is introduced to detect the wavefront, and the fault locating error that may caused by the detection is evaluated.Based on the results obtained above, a novel a novel fault location algorithm based on variant travelling wave speed are proposed. Relevant simulations are performed in EMTDC taking simplified Tian-Guang HVDC system for instance. The results show that the new algorithm can effectively guarantee the accuracy at any distance, which verify the correctness and feasibility of the algorithm.Finally, a theoretical guidance for the application of the novel algorithm to engineering practice is provided. The challenges that might face in the process are analyzed. The effects of some closely related factors to the accuracy of fault locating are also evaluated and some proper methods to eliminate the effects are addressed. |
PDF Full Text Request