Thispaperdescribes,bymeansofaVoronoihypersphere,thenearestneighborrelationsofallthefeaturesubmatricesinthefaultclassificationspaceandanalysesthedeviationdisturbanceanglesbetweenfaultfeaturesubmatricesandak-dimensionunitarymatrixofthemeasuredvoltagechangematrix.Withtheabovetwoconcepts,thispaperdiscussesthediagnos-abilityinthefaultclassificationapproach.Thepaperalsoclassifiesanddefinesthefaultdiagnosisproblems.Finally,thepaperderivesthecorrespondingnecessaryandsufficientconditionsforcorrectlocationoffaults.
