基于轨迹模式空间解耦及模式能量序列的振荡分析(三)时变性分辨率从摆次细化到时间断面

系列文章的前两篇以振荡模式的空间解耦代替频域解耦，并通过互补群模式的摆次能量演化来反映复杂振荡行为的特征。由于其对时变性的分辨率较低，也不利于讨论多模式之间的交互作用，故文中提出在每个积分步末端所对应的时间断面处，按实际变量值重新冻结映象系统的非哈密顿因素，按虚构的哈密顿系统来估计该断面后的不平衡功率-转角的曲线。进而评估各互补群模式的振荡总能量(或其裕度)的时间序列，将轨迹振荡能量序列分析方法的时间分辨率从按模式摆次细化为按积分步长，更好地反映振荡的局部时变性。针对分别计及调速器或计及机械功率周期性扰动的两个算例，揭示了系统“反常”振荡行为的机理。

Oscillation Analysis Based on Trajectory Modes Decoupled in Space and Mode-energy-sequence Part Three Time-varying Resolution Thinning from Swing to Time Section

In the first two articles of this series, the oscillation modes decoupled in frequency domain are replaced with those decoupled in space, and the characteristics of complex oscillation behavior are reflected based on the variation of the complementary-cluster inter-group swing energy. However, it is difficult to discuss the interaction between multiple modes due to the low resolution of time-varying characteristics. The non-Hamilton factors of image system are frozen according to the actual variable values at the time section corresponding to the end of each integral step. Therefore, the curve of the unbalanced power vs the power angle of the section is estimated according to the virtual Hamilton one-machine infinite-bus(VH-OMIB)system. Then, the time series of the total oscillation energy(or its margin)of each complementary-cluster mode is evaluated. Thus the time resolution of the analysis method for the trajectory oscillation energy sequence is changed from swing of the mode to integral step which can reflect the local time-varying characteristics of oscillation better. Finally, the mechanism of system abnormal oscillation behavior is revealed in the two cases with governor or cyclical mechanical power disturbance.