Voltage stability has become a very important issue for operating power systems close to their limits due to the continuous load increase and economic constraints. This paper discusses some important aspects related to the maximum loading margin in voltage stability studies. The proposed method is based on optimization problem for computation of voltage collapse point. The genetic algorithm is utilized to solve the parameterized nonlinear load flow equations. To reduce the computational burden, the optimization problem is examined in the weak area of the system which is defined by modal analysis. The proposed method is simple, efficient and quite fast for determining the maximum loading margin. Therefore it will be a suitable approach for online assessment of voltage stability problem. Simulation results for IEEE 14-bus system are shown to validate the proposed method.

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