Risk-based generator rejection protection system design in Taiwan Power System

In order to perform a rapid corrective action, prevent wide-area disturbances, and enhance power system reliability, there is a trend to design and implement inexpensive special protection systems (SPS) in recent years. However, excessive reliance on SPS can result in increased risk. In this paper, the generator rejection schemes (GRS), one of the simplest SPS, will be investigated for Taiwan Power System. Markov modelbased GRS will be studied for reliability assessments of SPS. Two GRS schemes will be analyzed for comparative studies: (1) one out of one rejection for one generator mechanism, and (2) two out of three rejections for one generator mechanism. Transient stability assessments are investigated by using DSATools. From our studies, the following statements can be concluded: (1) The reliability of two out of three rejections for one generator mechanism is better than that of one out of one rejection for one generator mechanism. (2) The power plant without generator rejection mechanism is more risky than the power plant with generator rejection mechanism when power output exceeds a threshold loading. (3) The critical clearing time indeed can be improved if GRS are applied for emergency control.