VOLTAGE STABILITY - ANALYSIS NEEDS, MODELING REQUIREMENT, AND MODELING ADEQUACY

The importance of representing dynamic loads by valid dynamic models i n dynamic analyses of voltage stability is demonstrated. Several dynam ic load models reported in the literature are reviewed. It is shown th at, for loads with slow dynamics or when the system voltage may be ass umed constant, small signal stability is independent of the load model used, provided the model parameter values are correctly chosen. The s ame results can also be predicted by steady-state analysis by appropri ately modifying the conventional power flow model. In large disturbanc e situations, and when the load dynamics exhibit fast response charact eristics, a detailed system modelling is needed. An argument is presen ted in favour of using the theoretically rigorous and well established models for loads with fast dynamic response, when detailed analyses a re warranted.