Power system static security assessment and evaluation using external system equivalents

Static security assessment and analysis using external system (Ward network) equivalent is presented. Contingency analysis is performed on the reduced network obtained using extended Ward equivalent. The Ward equivalent provides reasonably good results for contingency studies involving active power flows. Distribution factors method is used to perform contingency analysis. Fast line flow contingency screening is implemented for both the original unreduced network and the reduced network. The real power performance index (PIMW) that reflects the degree of severity of contingencies is calculated using the screening method and full AC load flow method. The effectiveness of the proposed method is demonstrated by performing contingency analysis on a standard 6-bus system, IEEE 14-bus, IEEE 30-bus and IEEE 57-bus systems, respectively. The performances of the reduced network and the screening method are compared with the traditional Newton–Raphson (NR) method and the results are discussed. The external network equivalent approach to security analysis was found to be suitable for fast line flow contingency analysis.