Indicating and mitigating voltage collapse comparing voltage stability indicators

Novel measures to indicate and mitigate voltage collapse in the power system are presented in this paper. The functionality of conventional and unconventional indicators and mitigating actions are tested in a case study using the IEEE Reliability Test System 1996. The results of this study show that two indicators, the Impedance Stability Index (ISI) and the Short-Circuit Capacity Index (VSI_SCC), together with activation information from overexcitation limiters in the system proves a valuable combination as a trigger of mitigating actions. Furthermore, active control of voltage regulator set points is identified as an effective action to prevent voltage collapse.