Optimization of Undervoltage Sensing Protection Logic in Guizhou-Guangdong HVDC Line I

Aiming at a fault of protection misoperation emerged from switches breakdown in the 500 kV Yandu station of Guangdong,this paper analyses the logic of undervoltage sensing protection and the reasons of the protection misoperation according to the transient fault record,and proposes an optimization scheme of undervoltage sensing protection. Based on simulations on different working situations with the PSCAD /EMTDC simulation model for the HVDC Guizhou-Guangdong Line I,the rationality of protection threshold value selected in this paper is proved. With modified HVDC protection software of RTDS for the HVDC Guizhou-Guangdong Line I based on the proposed optimization scheme,the on-spot fault recorder playback experiment shows that the optimization protection logic can avoid the undervoltage sensing protection misoperation caused by AC exterior fault.