Application of phasor measurements and partial energy analysis in stabilizing large disturbances

Precise time-synchronized phasor measurements are available today from the phasor measurement unit (PMU). One of the most promising uses of the PMU is for during-transient control applications. The work reported in this paper investigated the ability of synchronized phase angle measurements to identify impending instabilities through real time measurements, and to trigger remedial actions in time to prevent major power system outages. At question was feasibility and how many additional megawatts could be transferred when using the PMU to arm existing during-transient controllers. The partial energy function is defined and explained symbolically in terms of Kimbark´s equal area criterion and power angle diagrams. The four steps for accomplishing PMU-based detection of instability are outlined. The approach is applied to instability conditions in Bonneville Power´s 500 kV transmission network, USA. The effectiveness of the improved remedial action is demonstrated in terms of energy analysis and Kimbark diagrams and reported in terms of megawatts of increased power transfer