中文摘要：

基于Ibrahim时域法的基本思想，提出一种可以识别电力系统振荡特性的改进算法，并给出了详细推导过程。所提算法可以根据故障或正常操作扰动后电力系统指定观测量的自由响应数据，识别机电模式特征值。在Matlab仿真平台上，通过对一个4机电力系统和一个8机电力系统的实例分析，证明所提方法对振荡频率和阻尼比的识别准确度比较理想，而且识别速度快、需要PMU（相量测量单元）测量点少、不遗漏模式，有较好的应用前景。

英文摘要：

According to fundamental idea of Ibrabim Time Domain （ITD） algorithm, this paper illustrates an improved algorithm by which the small-signal stability can be assessed. Also, the course of concluding and principal formula about the improved ITD algorithm is introduced in detail. Using the real-time data sampled from free responses of selected variables in power system, which is disturbed by a fault or normal operation, the dominant eigenvalues are evaluated efficiently. In order to describe the identifying techniques, two simulation cases, one of which is a four-machine power system and the other of which is an eight-machine test system, are established in the MATLAB environment. The simulation results show that required modal information including oscillation frequency and damping is extracted successfully, and this technique also has the character of quick computation, needing fewer PMUs, without losing modes, and practical prospects.