Fault Analysis Method for Multi send HVDC System by Considering DC Control Characteristics

With a comprehensive consideration of the switching function model of convertor and the fault response characteristics of rectifier DC control system under various fault type, a simplified DC system model is established for fault calculation in sending end AC system. Based on the simplified model, combined with the sending power network equations and the fault boundary conditions of asymmetric fault, a multi send HVDC system fault calculation method is proposed. Based on CIGRE HVDC benchmark model, the PSCAD/EMTDC simulation model of a three send HVDC system is built to testify the proposed method fully. The results show that the proposed method is of simplicity, rapid convergence and more accuracy, and provides the analysis basis of protection setting and cooperation in multi send HVDC system.