Research on Comparison of Fault Current Fitting Methods for VSC-HVDC Grids

On the basis of summarizing the calculation methods and characteristics of the fault current of Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) (VSC-HVDC) grids, the first-order polynomial fitting, exponential fitting and Fourier fitting of fault current are studied in this paper. The effects of three fitting methods of fault currents of fault branches and non-fault branches in a typical 6-terminal true bipolar VSC-HVDC grid under the conditions of pole-to-ground fault, pole-to-pole fault and pole-to-metal return fault are compared. The fitting effect and error under three fitting methods of different fault locations are also analyzed. Through the analysis and induction of specific examples, it is concluded that the results obtained by the Fourier fitting method are the most consistent with the simulation results.