Protection of Multi-Terminal VSC HVDC Hybrid Transmission Line

This paper presents a fast fault detection scheme for a hybrid line in a multi-terminal (MT) voltage source converter (VSC) high voltage DC (HVDC) system. The proposed method is based on the primary and secondary protection scheme. The discrete wavelet transforms (DWT) with Teager energy operator (TEO) and voltage polarity comparison are applied to detect the faulted line for primary and secondary protection schemes, respectively. The main and backup protection schemes are based on non-pilot and pilot methods, respectively. The proposed main and backup methods are robust against high impedance faults (HIFs). The proposed protection scheme is verified under different fault points applied on an MT-HVDC test system. The case study is performed using PSCAD/EMTDC software. Simulation results show the effectiveness of the proposed protection method for the VSC HVDC transmission line.