Novel directional comparison protection based on travelling waves

This paper proposes a novel directional comparison protection. At its core is a directional element based on travelling waves. The directional element determines fault direction by the ratio of initial voltage and current travelling waves. In theory, if the ratio is equal to the surge admittance of the protected line, the fault is a reverse one; if the ratio is not equal to surge admittance of protected line, the fault is a forward one. In practice, appropriate thresholds are required and can also be set according to the practical situation. Using two directional elements and a proper communication channel, a new protection system can be constructed.