Network frame optimization method for defending multi-DC commutation failure

In a multi-infeed receiving-end power grid, the commutation failure in multiple HVDC systems will seriously threatens the safe and stable operation of the power system when serious AC fault occurs. Firstly, based on the concepts of electrical distance, this paper proposes a weakness evaluation index to find out the buses whose short circuit faults may cause commutation failure in multiple HVDC systems. Secondly, an index for finding out the key branches between a target bus and a point of common coupling (PCC) is put forward. Then, combined with MMC-HVDC transmission technology, a network frame optimization method for defending multi-infeed DC commutation failure is presented. Finally, the correctness and validity of the proposed method are verified by simulation in a modified New England 39-bus system using the simulation software PSS/E.