Estimating the Active Power Transfer Margin for Transient Voltage Stability

On-line security analysis is one of the important functions for modern power system control centers. It is well known that voltage magnitudes alone are poor indicators of voltage stability or security. Voltages can be near normal with generators, synchronous condensers, and SVCs near current limiting levels resulting in a possible voltage collapse. For on-line application, a pattern matching or interpolation method rather than analytic approaches may be most appropriate. In this paper, an ANN is used to estimate the active power transfer margins for transient voltage stability. The method is applied to a small system, the New England 39 bus system, and a large system, the WSCC system. The numerical results show that the ANN can give accurate and satisfactory estimation for the active power transfer margins.