An Online Method to Identify the Voltage Stability of Power Systems during Transients

During transients, the instability of the power system can attribute to the angle instability as well as the voltage instability. The angle and voltage stability are entangled with each other under such circumstances. The angle stability has been well-studied, and many online stability assessment approaches have been put forward to this end. Yet the problem to determine the voltage stability of power systems during transients are seldom discussed. In this paper, an online method to identify the voltage stability of the power systems is proposed. The proposed method is based on the nodal equivalent method, and also utilities the measured data to identify the parameters that are applied to determine the voltage stability of the system. The proposed method can predict the voltage stability of the power system in advance even the voltage instability has not occurred. Simulation studies with a simple 3-bus system and the IEEE 39-bus system demonstrate its effectiveness.