This paper determined proper blocking tap changer threshold voltage as countermeasure to prevent cascading failure in KEPCO system. Cascading failures are difficult to address with centralized emergency control because of unexpected characteristics depending on power system conditions. This results is an approach for fast and conservative installation in a system that has no countermeasures. The performance of the proposed method is described by applying to the practicable cascading failure scenario in Korean power systems (KEPCO system) with explanation of simulation environments to derive long-term voltage instability. The proposed strategy effectively copes with cascading failures contingencies by preventing the voltage collapse to ensure reliability and reducing the unnecessary operation of on load tap changer to improve the reasonability.

Cascading Failure,Long-term voltage stability,Blocking tap changer