Power system reduction techniques for direct transient stability methods

To speed up transient stability assessment using direct methods the authors use power system reduction techniques, combining the composite electromechanical distance (CED) approach, to identify and ultimately aggregate machines (almost) irrelevant to the transient phenomena with node reduction, to eliminate irrelevant nodes while possibly taking advantage of other techniques, such as sparsity preserving and connectivity based ones. The resulting approach is illustrated for the French EHV power system. It uses direct methods of the extended equal area criterion type, together with a CED appropriately tailored to the system specifics and various node reduction techniques. Many variants so devised are compared. It is found that the CED approach significantly speeds up the direct methods while fully preserving accuracy