中文摘要：

弱联系的互联电力系统容易发生低频振荡已成为危及系统运行安全一个不容忽视的因素。根据系统受扰轨迹识别系统的主导振荡模式有重要意义。该文提出一种基于轨迹识别电力系统主要振荡模式的信号能量法，对单机无穷大系统，建立了受扰轨迹能量变化与振荡模式阻尼比之间的解析关系。通过构造与受扰轨迹在能量意义下等效的二阶系统，该方法也可用于识别多机系统的主导模式。由于所需的受扰轨迹既可取自于广域量测系统，也可通过仿真获得，该方法易于用来研究多机系统的主要振荡模式。运用信号能量法还可以识别不同时段主导振荡模式的变化。在单机对无穷大系统和EPRI．36节点8机系统算例中，证明所提方法的有效性。

英文摘要：

The low-frequency oscillation seems easier occurring in a weak-interconnected bulk power system. It even threatens the security of system operation. A mode identification based on trajectory is significant. For identifying the main oscillation mode, a new method based on signal energy analysis of disturbed trajectory has been proposed. The analytical relationship between the energy of disturbed trajectory and the damping ratio of corresponding oscillation mode has been built up in the case of one machine to infinite bus system. By means of constructing a fictitious 2-order mode that is equivalent in energy profile with the disturbed trajectory, the main oscillation mode can be recognized. The proposed method can easily be used, because it only relies on disturbed trajectory, which could get from either WAMS or digital simulation. The variety of main oscillation mode with the time progress has been recognized by the proposed method. The validity of the proposed method has been verified in an SMIB system and an EPRI-36 bus system.