MMC-HVDC grids transmission line protection method: Based on permutation entropy algorithm

Modular multilevel converter high-voltage direct current is increasingly used for electric energy transmission and is a method for addressing energy distribution. However, when a DC short circuit fault occurs in the transmission line, the fault current rapidly increases, posing a threat to the normal operation of the MMC-HVDC grid. Therefore, it is necessary to quickly identify faults in the transmission line to protect the safe operation of the grid. To address this issue, this paper proposes a novel protection method for MMC-HVDC grids based on the permutation entropy algorithm. The permutation entropy algorithm exhibits good performance in analyzing the degree of disorder in signal data. In this paper, wavelet transform is used to decompose the sampled signal, extract detail coefficients at different frequencies, and then calculate permutation entropy values to identify faults based on their characteristics. Finally, a simulation model of an MMC-HVDC grid is built using PSCAD/EMTDC to verify the accuracy of the proposed method. The results show that the proposed method performs well under different fault distances, fault resistances, and noise interference.