Abstract
In recent years, the construction of new transmission lines is increasingly difficult due to environmental concerns, land acquisition, etc. As a result, the reliability of the entire power system is not adequate. One simple way to solve this task is to apply special protection systems to perform a quick corrective action. Thus, the entire system stability will be enhanced. System protection schemes include the generator tripping, load shedding, high speed reactive voltage compensations and congestion mitigations. In this thesis, we will focus on Markov model-based risk assessments for special protection systems using generator rejection schemes. This includes (1) one out of one rejection for one generator mechanism, (2) two out of three rejections for one generator mechanism, and (3) one out of one rejection for two generators mechanism. Based on transient security assessment tools DSA Tools, a user-defined model is utilized for model developments first. Then, transient stabilty assessments are investigated. From extensive simulation results, we have the following observations: (1) Regarding reliability analysis, two out of three rejections for one generator mechanism has 97.87% greater than 96.021% of one out of one rejection for one generator mechanism. (2) Regarding risk assessments, the power plant without generator rejection mechanism is more risky than the power plant with III generator rejection mechanism when power output exceeds the maximum load. Therefore, using redundant systems can effectively increase system reliability and reduce risk. (3) The critical clearing time, Angle Margin (AM), and Swing Margin (AM) can be indeed improved if generator rejection schemes are applied for emergency control.