Investigation on the electromagnetic transient characteristics of an AC-DC interconnected system under different faults

The electromagnetic transient can be used to analyze the stability of power systems. In the paper, the electromagnetic transient of an AC-DC interconnected system under different faults is investigated, and interaction between the AC system and DC system is analyzed. Firstly electromagnetic transient models for the components in a high voltage direct current (HVDC) transmission system are presented, including model for converter transformer, harmonic filters, transmission line and control system. Then simulation based on electromagnetic transient model for a ± 800 kV bipolar HVDC-AC interconnected system is carried out, and both the steady state and step response performance are checked to verify the accuracy of the model. Finally electromagnetic transient of the system under different faults is investigated, including different grounding faults on AC side, fault on DC side and fault of filters. Transient responses are analyzed, including the recovering time from oscillation caused by faults and possibility of commutation failure (CF).