Voltage Vulnerability Measurement Based on Energy Stability Region

Taking into account the fact that voltage are mainly affected by reactive power, this paper proposes an approach to assess the voltage vulnerability of power systems based on a concept of energy stability region. Two indexes have been developed, i.e., degree index, which is the energy corresponding to the busbar voltage, and trend index, which is the sensitivity of the energy with regard to the voltage affected by the reactive power injection set and also an indication of the trend of the change of the energy stability region of energy injection. Analyses have been carried out on how changes in reactive power injection the network topology affect the two indexes. The effectiveness and feasibility of the proposed method are demonstrated on the IEEE-30 bus system.