An improvement on steam turbine generator trip caused by voltage sag

This paper attempts suggest improvements on Nan-Pu combined cycle power plant, which is located in Kaoshiung of Taiwan. As far as transient outage of power system in southern Taiwan is concerned, the steam turbine generator would trip but the gas turbine generator would keep running. The outages had occurred several times since commercial synchronization; it happened as many as three times from January to June in 2001. Consequently, we found that the settings of overcurrent protection relay of excitation transformer were improper in our investigation and through with the other plant. By modifying the relay settings, this defect has already been corrected fully. The project not only improve working achievement, but also enhance transient stability of overall power system in Taiwan.