中文摘要：

提出一种具有解析性质且能近似用于描述系统电压稳定性的特征指标，基于该指标提出一种计算电压稳定边界的两阶段混合潮流方法。在阶段1中，利用二分法原理确定重复潮流计算过程中的功率增长步长，快速求出系统的近似电压稳定边界；在阶段2中，采用连续潮流技术对电压稳定边界进行精确计算；在整个计算过程中，利用提出的特征指标识别系统是否已经接近于极限运行状态，进而判别何时进行阶段1和阶段2的更换。仿真结果表明，所提方法可以减少潮流计算的次数，从而提高电压稳定边界的计算速度。

英文摘要：

An analytical index is introduced to approximately describe the system voltage stability,based on which,a two-stage mixed power flow method is proposed to calculate the voltage stability margin. In stage one ,the bisection method is applied to set the step size of power in the repeated power flow calculation for quickly determining the approximate voltage stability margin of system. In stage two,the continuous power flow technology is employed to accurately calculate the voltage stability margin. In both stages,the proposed index is used to identify if the system is close to the collapse point and to further determine when the stage should be alternated. Simulative results show that,the proposed method reduces the repeat times of power flow calculation and speeds up the calculation of voltage stability margin.