Transient Harmonic Voltage based Protection Scheme for Multi-terminal HVDC Transmission Networks

DC faults originate uncertainty in the progression of multi-terminal high voltage dc (MTDC). The fault current makes a rapid, sharp peak, but isolation of the entire network is not a viable solution under a specific fault circumstance. Rapid detection of a fault with high accuracy is essential for the reliability of the entire network. This paper proposes a fault detection scheme to sieve voltage harmonics from system voltage by using Discrete Fourier transform (DFT). Voltage harmonics rapidly employed the fault detection at the converter stations for MTDC networks without communication. The proposed scheme is also capable of classifying internal and external fault by counting the 12
^th
harmonic pulse count. The simulations are executed in PSCAD for four terminal MTDC transmission network to vindicate the performance of the proposed scheme. Comprehensive analysis of test results verified that the proposed scheme, in addition to rapid and precise fault detection, can also efficiently classify the nature of faults. Moreover, consequences proved its promising performance for numerous MTDC faults.