Abstract The paper shows that, for certain classes of power system models, if time-varying delays are replaced with their average value, the small-signal stability analysis returns conservative results, while showing a lower computational burden. The paper first compares, through an exact analytical approach, the delay margin of a second-order electromechanical model with inclusion of constant, square-wave, and Gamma distributed delays. Since the analytical approach is not viable for realistic power system models, the paper also develops a novel general method to calculate the eigenvalues for systems with time-varying stochastic delays that cannot be described by an analytical probability distribution function. These kind of delays are relevant for the study of wide-area measurement systems (WAMSs). The IEEE 14-bus system serves to compare the stability margin and the critical damping ratio of a constant and two WAMS delay models solved with the proposed numerical method.

中文翻译：

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具有恒定和时变延迟的电力系统的延迟裕度比较

摘要 本文表明，对于某些类别的电力系统模型，如果将时变延迟替换为其平均值，则小信号稳定性分析返回保守结果，同时显示出较低的计算负担。本文首先通过精确分析方法比较了包含恒定、方波和 Gamma 分布延迟的二阶机电模型的延迟裕度。由于分析方法对现实电力系统模型不可行，因此本文还开发了一种新的通用方法来计算具有无法用分析概率分布函数描述的时变随机延迟系统的特征值。这些延迟与广域测量系统 (WAMS) 的研究有关。