3、em Security and New Technology,Chongqing400044,China;2.guiyangpowerguiyang550001,chian)[Abstract]Atpresent,twoterminalpowersupplyhasbeenthecommonmode.Butclosedloopdesignandopenloopoperationiscommonlyusedinthedomesticdistributionnetwork.Whenloadisswitchedorelectricalequipmentismai