The high-amplitude magnetizing inrush current generated during the no-load closing of converter transformers often leads to commutation failure in the hierarchically connected UHVDC system. To suppress commutation failure in the non-inrush current layer

a commutation failure suppression strategy based on DC current prediction and commutation area coordinated control is proposed. Firstly

starting from the mechanism of commutation failure caused by magnetizing inrush current

we present an index for rapidly evaluating commutation failure in the inrush current layer. Secondly

based on the evaluation index of commutation failure in the inrush current layer

the dominant factors of commutation failure in the non-inrush current layer are clarified. Then

through DC current prediction

the overlap area required by the converter in the non-inrush current layer is compensated in advance. Finally

the effectiveness of the proposed control strategy is verified through the PSCAD/EMTDC simulation model. The simulation results show that the proposed control strategy can be used to effectively reduce the probability of commutation failure in the non-inrush current layer

improve the fault recovery performance of the DC system

and enhance the system stability.