Quick Calculation of DC Fault Overvoltage in Two-Send HVDC System

China’s resources and productivity exhibit significant disparities, necessitating the integration of multi-infeed HVDC into a common infeed system. Notably, the Three-North Region boasts abundant renewable resources, particularly wind power. Addressing the challenge of substantial wind power consumption, the implementation of high-voltage DC transmission projects has led to the establishment of extensive large-scale DC sending systems within the region. Within multi-send HVDC systems, the substantial power fluctuations have the potential to induce severe overvoltage in the vicinity of the converter bus. This, in turn, can trigger the disconnection of wind turbines and other equipment, exacerbating the risk of severe accidents. In this study, a comprehensive analysis commencing from the mathematical model of a two-send HVDC system is embarked on. By doing so, the overvoltage expression following a DC fault in such systems and subsequently explore the correlation between the overvoltage magnitude and individual equivalent impedance values is derived. The findings underscore that varying changes in equivalent impedance yield distinct effects on the overvoltage at the system’s converter bus. Moreover, the precision of the overvoltage expression through rigorous verification is substantiated.