The principle of single-ended transient based voltage protection for UHVDC transmission line

The smoothing reactor, DC filter and PLC filter form the physical boundary of UHVDC transmission line. The frequency characteristics of UHVDC transmission line and line boundary are analyzed, and the attenuation of high frequency fault transient signal caused by UHVDC transmission line boundary and transmission line is studied. The protection area of transient based protection of UHVDC transmission line which is widely used now is analyzed, and it is concluded that the transient based protection method can not protect the whole transmission line. Considering the attenuation of high frequency fault transient signal caused by UHVDC transmission line boundary and transmission line, single-ended transient based voltage protection method of UHVDC transmission line which uses protector to distinguish the opposite inside fault from outside fault is studied. The actual parameter simulation model is built, and the single-ended transient based voltage protection method studied in this paper is simulated.