Hybrid HVDC system fault transient analysis considering traveling wave propagation and converter control response

Abstract

Accurate fault analysis is essential for protection and control design of hybrid HVDC transmission system. This paper proposes a dc fault transient analysis method, which considers both the traveling wave propagation process and converter control response. Firstly, the multiple reflected and refracted traveling waves at line terminals as well as fault point are calculated by building propagation coefficient matrices. Secondly, the transfer function between the converter equivalent source and the traveling wave transients is built, then the fault current and voltage are calculated by compensating multiple traveling waves with corresponding control response. Compared with existing methods, the proposed method can calculate long-period traveling waves in a simplified way, and implement more accurate analysis for the converter response caused by the basic control strategy and the fault control strategy. An LCC-MMC HVDC system is built based on PSCAD/EMTDC, and the simulation cases are carried out to verify the correctness and superiorities of the proposed method. Finally, the impact of control response on the performance of traveling-wave-based directional protection is evaluated by the proposed fault analysis method.