Under voltage load shedding utilizing trajectory sensitivity to enhance voltage stability

Under voltage load shedding is a proficient counter-measure action against voltage instability/collapse. UVLS procedure is an effective means to maintain voltage stability of a power system when the system´s voltage is just about to collapse following some disturbances. This paper proposes an advanced under voltage load shedding based on trajectory sensitivity analysis for voltage stability enhancement. Trajectory sensitivity analysis is a technique based on linearizing a system surrounding a certain trajectory and employs time domain simulations. This technique computes the sensitivity of the dynamics relating to the constraints. Trajectory sensitivities between bus voltages are calculated by using hybrid system´s trajectory sensitivities to obtain sufficient amount for load shedding. Furthermore, trajectory sensitivity index at all buses is calculated to select the most appropriate location of load shedding. Dynamic simulations are performed with the 14 bus RTS IEEE as case study.