Voltage Correlation Based Single Pole-to-Ground Fault Detection of MMC-HVDC Transmission Line

Through analysis of various fault voltage characteristics of modular multilevel converter high voltage direct current (MMC-HVDC) transmission system, it shows that the positive and negative voltage relationships of direct current transmission lines with single pole-to-ground faults are obviously different from other faults. Hence, Pearson correlation coefficient is used to describe the degree of difference in this work. In the case of single pole-to-ground fault, correlation coefficient is positive and close to 1, while as for other failures, correlation coefficient is negative and close to −1. This article analyzes the mechanism of correlation coefficient to withstand transition resistance and verifies the effectiveness of the proposed method under high resistance grounding fault. A novel scheme is proposed by combining the quantity sum of voltage variation characteristics, which can effectively identify fault pole. The proposed scheme needs smaller time window and owns high efficiency, as well as great robustness to transition resistance.