Under-voltage load shedding is an important measurement to maintain the voltage stability in power systems. In this paper, a new combined index is proposed for under-voltage load shedding. The proposed index is weighted combination of importance, sensitivity and value of loads. This is of paramount importance, since three vital factors such as importance of load, sensitivity of minimum eigenvalue of load flow Jacobian respect to load and the amount of loads are considered for optimal under-voltage load shedding. The algorithm accounts constraints not only in present operating condition but also for predicted next interval load. The proposed method is applied on IEEE 14-bus test system. This paper formulates the optimal under-voltage load shedding problem for power system as a Nonlinear Programming (NLP), and it solves the proposed problem using Generalized Algebraic Modeling Systems (GAMS) software package with CONOPT solver. Results have been compared with those researches based on sensitivity analysis. The results showed effectiveness of proposed index. This proposed index can be used in selecting candidate buses in different power system problems.
