Combination Load-Flow and Stability Equivalent for Power System Representation on A-C Network Analyzers [includes discussion

Abstract

MEMBERAIEE NE ofthemajorproblems encountered whenan extensive power systemistoberepresented on an a-cnetworkanalyzer isthatofdeveloping properequivalents forthoseportions of thepower systemwhichare nottobe represented indetail either because of limitations oftheanalyzer orbecause of a desire forsimplification oftheover-all system. Several methods are currently a-,ailable fordeveloping fairly satisfactoryequivalents forload-flow studies. Thereisno correspondingly satisfactory methodavailable fordeveloping an equivalent forstability studies where there areseveral points ofinterconnection b2tween thatportion ofthesystem tobe retained as realandthatportion tobe represented byan equivalent. Stability equivalents whichhave beenusedhave notbeenidentical inperformance toloadflowequivalents. Modification ofthea-c analyzer setuphasbeennecessarywheneveritisdesired tochangefromasystem representation suitable fora load-flow study toonesuitable for astability study. A methodispresented fordeveloping a new equivalent which can beusedinterchangeably forbothload-flow andstability studies. Included also aretheresults ofan investigation madewiththe useofan a-cnetwork analyzer totestthe validity oftheproposed new equivalent. Several ofthemethodsavailable fordeveloping load-flow equivalents are summarized briefly. Thepresent practice of developing equivalents forstability studiesisdiscussed.