A PMU based special protection scheme: a case study of Taiwan power system

This paper proposes a special protection scheme to prevent power system blackout due to a sequence of relay trip events based on phasor measurement units (PMUs). In a control center, we use PMU's to monitor the generators and the major EHV transmission lines of a power system, and apply an instability prediction algorithm for initiating a special protection schemes (SPS) to avoid a sequence of relay trip events whenever necessary. When a fault happens, we group the generators swinging coherently and reduce the system to One-Machine-Infinite-Bus (OMIB) system. The remedial control actions consist of load shedding and generation tripping. The strategy for determining the amount of remedial control actions is a proposed relay setting limited equal-area criterion for OMIB. A case study of Taiwan power system assumed to be equipped with proposed special protection scheme is conducted. Encouraging results are obtained.