双时间尺度电力系统动态模型降阶研究(二)——降阶与分析

电力系统是一个多时间尺度的大规模非线性系统，其稳定性分析非常复杂。在实际的电力系统稳定分析中，具有快变特征的电磁变量的动态通常被略去，通过系统降阶使稳定性分析得以简化。然而，一个十分重要的问题是在什么条件下系统的降价不会引起质的错误。同时，降价后的系统代数方程的特征也需要进行充分的研究，以便对降价后的系统模型进行分析。文中以基于物理电路的计及快慢动态的电力系统奇异摄动模型为基础，研究了系统降价的条件，得到了当系统负荷模型为感应电动机和并联线性阻抗时系统降价对系统稳定分析不会引起质的错误的重要结论。另外，文中还证明了在上述负荷模型下，系统降价后的代数方程解流形是正则子流形。

STUDY ON THE ORDER REDUCTION OF TWO-TIME SCALE POWER SYSTEM DYNAMIC MODELS: Part Two Order Reduction and Analysis

Power system stability analysis is extremely complex due to its multi time scale nature, high dimensionality and non linearity. In order to make efficient stability analysis, a common practice is to neglect very fast transients. However, this might cause qualitative error in stability analysis. Under what conditions the fast dynamics can be neglected is still an important theoretical question to be answered. Moreover, it is significant to investigate the characteristics of the resultant algebraic equations of the reduced system. In this paper, conditions for reasonable reduction of the system are studied by means of a two time scale model based on physical circuits of power systems. An important conclusion is reached that if the load model is treated as an induction motor in parallel with linear impedance, no qualitative error will be caused in stability study by neglecting fast electromagnetic transients. Under the same condition of load model, the solution manifolds of the resultant algebraic equations are proven to be regular sub manifolds.