MMC-HVDC line fault identification scheme based on single-ended transient voltage information entropy

Abstract

High resistance faults are the main cause of protection refusal action in high voltage direct current transmission line protection based on modular multilevel converters (MMC-HVDC). Furthermore, noise can affect the protection method. It is imperative to mitigate the High resistance faults and the influence of noise on the protection method. This paper analyzes the reasons for the difference in the initial voltage slopes of the internal and external faults under the traveling wave level. Subsequently, it analyzes the reasons for the difference in the complexity of the internal and external fault waveforms. Based on these analyses, a complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) information entropy method for line fault identification in the presence of white noise is proposed in this paper. The fault identification criteria are subsequently used to identify the internal and external faults. The transmission model of 77 level bipolar MMC-HVDC system grounded via a grounding electrode lead is simulated in the RTDS. The results show that the proposed method can enhance the anti-interference ability of the signal, identify the high resistance fault effectively and reliably, and avoid the error problem caused by a synchronous clock.