A Study on Some Switching Aspects of a Double Circuit HVDC Transmission Line

A double circuit HVDC transmission linie equipped with a factacting dc circuit breaker has been studied in three modes of switching. Load breaking in one line and transfer to the other was investigated by utilizing an HVDC system simulator; breaker duty was easy and system disturbances were minimal. Fault clearing with and without system control assistance was investigated by use of a digital computer; breaker duty was more severe when control assistance was not utilized, but the duration of the system disturbance was reduced. No unacceptable system or breaker overvoltages were observed. The digital computer program was comprehensive, in that it modeled not only the line and terminal configurations but also the dynamic control characteristics of the Pacific Intertie.