Pilot Protection of AC System in AC-DC Interconnected Grid Based on Traveling Wave Refraction and Reflection

To solve the problem that the voltage travelling wave protection at the AC bus is difficult to detect in the AC/DC interconnection network, a frequency protection principle of the line waveguide using the phenomenon of travelling wave catadioptric is proposed in this paper. According to the catadioptric phenomenon when the discontinuity of traveling wave impedance meets the wave, the fault area is identified by using the different refraction and catadioptric coefficients of faults inside and outside the region. In PSCAD/EMTDC environment, the AC-DC interconnection network model is established, and the protection principle is verified by MATLAB.