A new contingency ranking method (power systems)

A contingency ranking method for detecting voltage problems is proposed. The method is based on the AC network model and a voltage-sensitive performance index (PI). An efficient algorithm is proposed for the computation of the change of the performance index with respect to each contingency. The method accounts for the effects of: voltage regulators; discontinuities arising from generation bus limits; discontinuities arising from regulating transformer tap limits; and voltage-dependent loads. The concept of bus stiffness is introduced to provide a priori knowledge of the accuracy of the ranking method. The computational requirements of the proposed method are comparable to that of one iteration of the Newton-Raphson power flow. The method is suitable for online voltage security assessment.<>