Typical principles of traveling wave (TW) protection in high voltage direct current (HVDC) projects are summarized in this paper. The DC line traveling wave protection (WFPDL) of SIEMENS applied in TianGuang DC project and the protection scheme of ABB Company in SanGuang DC project are studied whether they are suitable for the DC line protection of two-terminal hybrid DC systems. The pole-to-ground short-circuit fault of the DC line in a hybrid bipolar HVDC transmission system is simulated on the PSCAD/EMTDC. The influences of the fault location as well as the fault resistance are considered. A large number of transient fault data are processed and analyzed by MATLAB to design the setting values of protections. The conclusion are that the current TW protection schemes commonly used in DC projects are able to quickly detect the DC line faults while they have limited abilities to accurately select the faulty one for the pole-to-ground fault and are insensitive to failures with high resistance at the end of the DC line.

Fault simulation,Hybrid HVDC system,Traveling wave protection,DC Lines,Applicability analysis