An analytical sensitivity index for load shedding to avoid voltage instability

Load shedding is a very important measure for power system voltage instability prevention. This paper proposes a novel analytical sensitivity index to determine the optimal load shedding locations to avoid voltage instability. An impedance ratio index is first presented to indicate the voltage instability of load buses, and based on this, the sensitivity index is derived to identify and rank the load buses to be shed. Case studies have been conducted on the IEEE 30 bus system, and the simulation results show that the proposed indexes could effectively determine the load shedding locations for voltage instability prevention.