Abstract
Due to recent energy transformations in Taiwan, Taiwan power company planned to install several new generation units in DT power plant. However, due to the difficulty to construct new EHV transmission lines in its neighboring area, the system will experience transient instability problem under severe N-2 conditions. In order to tackle out this challenging task, two techniques, including system integration protection scheme (SIPS) and automatic reclosing (AR) of transmission lines are considered. For three-phase faults, the generator rejection scheme (GRS) in SIPS is recommended for quickly maintaining the power balance. The reliability-based GRS is studied in this paper. Redundant voting mechanisms are considered to reduce the risk of inappropriate generation rejections. Settings of the arming threshold of the GRS are investigated under the calculation of the risk. For other temporary non-severe N-2 faults, multi-phase automatic reclosing (MRAP) is recommended to restore the system in the timing manner. Impacts of unbalanced fault current with respect to the withstanding capability of the generator are also outlined. Simulation studies are conducted to validate the proposed solution.