In order to research the operating characteristics of Jiangsu power grid with Jin-Su UHVDC accessing

and the influence on Jiangsu power grid after AC system failure or bipolar blocking

based on higher load in summer of Jiangsu power grid

the Jin-Su UHVDC transmission electromagnetic transient model and the electromechanical model of remaining Jiangsu power grid on ADPSS（power system digital simulation device）are built up. The stability of Jiangsu power grid with Jin-Su UHVDC accessing by electrical-electromagnetic hybrid typical fault simulation is studied and the impact on stability margin of Jiangsu power grid with Jin-Su UHDVC accessing is analyzed. The restart process after bipolar blocking is also researched. Simulation and experimental results show that the model can accurately reflect operating characteristic of UHVDC transmission from Jinping to southern Jiangsu; south of Jiangsu area and key line static voltage stability limit can be promoted by accessing UHDVC transmission from Jinping to southern Jiangsu; Jiangsu power grid can operate stately during bipolar blocking or typical fault in AC system; Jiangsu power grid can restart smoothly after bipolar blocking.