Time-Domain Simulation Investigates Short-Term Voltage Stability with Dynamic Loads

Appropriate modeling of dynamic loads is of primary importance in voltage stability studies, especially increasing use of induction machines in both consumption and generation. This paper is mainly related to short-term voltage instability depending on time domain simulation. The actuality of voltage instability research is summarized, and the mechanisms of short- term voltage stability are explained. A simple power system will simulate the load dynamics showing how a short-term voltage collapse occurs. Based on simulations, this paper analyzes frequency decay and voltage decay of power system with large generating unit out of service depending on the load model and system condition. It is useful to realize the impact of load characteristics on voltage stability and low frequency of power system, and properly design the under-frequency load shedding and under-voltage load shedding schemes to improve the power system stability.