A remedial control scheme protects against transient instabilities based on phasor measurement units (PMUs)-a case study

This paper proposes a fast remedial control scheme to prevent power system blackout due to the severe fault at the major EHV transmission line, which transfers large power between areas. The authors use PMUs to monitor the generators and the major EHV transmission lines of a power system, and apply fault detection/location system to precisely detect/locate fault for initiating remedial control actions to avoid a sequence of relay trip events whenever necessary. Real-time phasor measurements are then use to estimate the parameters of OMIB. The remedial control actions consist of load shedding and fast-valve control of turbines. The strategy for determining the timing and amount of remedial control actions is a proposed line-based equal area criterion. The proposed scheme is tested with the Taipower system, which experienced a severe fault at a major EHV tie-line which carried more than 1500 MW and caused successive relay trips resulting in power system blackout. Almost total 83% consumers had an interruption in 729-event. The authors simulate the scenario of 7a 29-event and the proposed scheme using the PSS/E-24 simulator program. Encouraging results are obtained.