Reliability assessment of UHVDC transmission system based on bipole symmetry

This paper proposed a reliability assessment method of ultra-high voltage DC (UHVDC) transmission system. Considering the bipole symmetry of UHVDC transmission system, the state space model for evaluating reliability of UHVDC can be simplified for effectively reducing the problem dimension. Then, due to the standby effect of the alternating current filter and the recovery effect of the converter bridge, the Universal Generating Function (UGF) method is used to realize the state combination of the unipole multi-state system. Case studies of typical UHVDC transmission system are presented to illustrate the proposed method. Sensitivity analysis is also conducted to quantify dependency of reliability on parametric change.