A Novel TQWT based Protection and Coordination Scheme in Multiterminal VSC-HVDC Systems

Although the conventional protection system can provide sufficient protection for a point-to-point
high voltage direct current (HVDC) system, fault detection and protection coordination in
multiterminal HVDC (MTDC) systems still significant challenges. This paper presents a non-pilot
fault detection and protection coordination technique for the MTDC systems. Initially, an
extremely rapid fault detection method is proposed based on the energy of a tunable Q Wavelet
transform (TQWT) signal processing technique. The proposed technique enhances fault detection
performance by adjusting the wavelet transform (WT). Additionally, this study analyzes the impact
of the Q-factor on the MTDC protection system. Finally, a protection coordination strategy with
the main and backup protection systems is presented. A case study is conducted using
PSCAD/EMTDC software, and MATLAB is employed to extract signal features. Simulation
results confirm the accuracy and rapidity of the proposed method for the MTDC protection
systems. The proposed method can detect the faults in approximately 1 ms under different fault
types with high impedance faults (HIF) and noise.