High frequency-based protection algorithm for meshed MTDC systems

This research presents a high frequency-based algorithm for zonal protection of meshed Multi-Terminal high voltage Direct Current (MTDC) systems. Discrete wavelet transform (DWT) is used to capture high frequency current transients from one end of each line. The faulty line is identified by analyzing two distinct high frequency bands form the captured transients. The characteristics of these current transients during normal condition are different from faulty condition. A four-terminal meshed MTDC model is used to test the performance of the protection algorithm. Various faults with different fault scenarios were simulated using four-terminal meshed MTDC model. The simulation results showed success of the algorithm in identifying internal faults. Moreover, the high frequency algorithm showed robustness against other abnormal conditions such as AC faults and sudden change of wind power.