Real-time preventive control strategy for maintaining secure voltage stability margins

This paper tackles the voltage stability problem, by proposing preventive control strategies to maintain secure margins to voltage collapse. These control strategies are intended to be used in operation planning and real time operation environments. The main goal is to identify appropriate preventive control actions that can be quickly implemented in situations where the system presents a small security margin to voltage collapse. The proposed method should also work after the occurrence of contingencies. The innovation consists of meeting an optimum situation without the full use of some of the available resources. The formulation is such that preserves the most sensitive controls for future use in case of further emergencies. A detailed discussion of the control philosophies is presented in the paper. Simulation results for the IEEE 14 bus system and two realistic Brazilian systems demonstrate the efficiency of the proposed method.