| Undesirable tripping of generators contributed to the 1996 and 2003 blackouts in the U.S. Tripping of these generators initiated by over-excitation protection can lead to a shortage of reactive power supply. An effective way to prevent cascaded events is to identify the anticipated operations of generator protective devices such as over-current relays. For a given contingency, the post-disturbance field currents can be obtained from the results of steady-state contingency evaluation in the on-line security assessment process. However, their accuracy is inadequate compared with the post-contingency field current obtained from off-line time-domain dynamic simulations. In this thesis, a Fuzzy Inference System (FIS) is proposed to correct discrepancies between post-contingency field currents obtained from steady state contingency evaluation and the corresponding values obtained from time-domain dynamic simulations. Post-contingency field currents obtained from steady-state security assessment can be corrected on-line using an FIS constructed off line. A 200-bus system model is used to validate the performance of the developed FIS. |
