A controlled islanding method based on the recognition of the end of power flow path was proposed to solve the roblem of system insecurity caused by low voltage of system buses which are near the system partition surface. In addition, the problem caused by bus voltage was considered. The inappropriate network structure was demonstrated that it is the root of poor condition of bus voltage, and the relationship of structure change and bus voltage stability was summarized. On the other hand, to solve the bus voltage problem, an improved method with the principle of breaking path end of power flow was proposed. The result showed that, the proposed method performs better than reactive power compensation or traditional methods in improving the bus voltage condition after controlled islanding. In this way, static security of isolated power system can be promoted.
