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