Pole-to-ground fault current estimation in symmetrical monopole high-voltage direct current grid considering modular multilevel converter control

摘要

This Letter proposed a novel method to accurately estimate the pole-to-ground fault current in symmetrical monopole high-voltage direct current grids. To avoid simulation's time consuming and difficult modelling, the converter is equivalent to the simple resistor LC circuit, and the state space including negative pole and positive pole is established for pole-to-ground current estimation. To enhance the accuracy of the estimation, the influence of converter control is considered in the estimation. It is found that the dc voltage control mode would impact the fault current rather than the power control mode. In addition, the accuracy can be improved a lot when the control is taken into consideration in fault current estimation. The simulations validate the proposed method finally.