Increasing penetration of Renewable Energy (RE) based Microgrid (MG) introduces either beneficial or detrimental effects on power system stability. Uncertain condition of RE influences the dynamic behaviour of critical modes of power systems which potentially alter damping and increases the risk of oscillatory instability. On the other hand, it also reduces generator and transmission lines stress, enhancing the system stability. More complex MG control also leads to the occurrence of interaction among critical modes. More specific modal interaction in terms of resonance phenomenon potentially emerge when the engaged modes align both in damping and frequency of oscillation. In this paper, impacts of uncertain power injections from the RE based MG on small signal stability are thoroughly investigated using Monte Carlo (MC) simulation. From eigenvalues analysis, it was monitored that under RE uncertainties, the critical modes behaved randomly and unpredictably. However, the cumulative distributions of critical modes indicated that the additional power injections from the MG system introduced a positive impact in enhancing system stability. The presented work further discussed interaction among local, inter-area and control modes of MG due to variation of system parameters using a novel index known as Modal Interaction Index (MII). From several case studies, it is observed that MG contributed to mitigate resonance and modal interaction.

基于可再生能源 (RE) 的微电网 (MG) 的渗透率不断提高，会对电力系统稳定性产生有益或有害的影响。RE 的不确定条件会影响电力系统临界模式的动态行为，这可能会改变阻尼并增加振荡不稳定的风险。另一方面，它还降低了发电机和输电线路的应力，提高了系统稳定性。更复杂的 MG 控制也会导致临界模式之间相互作用的发生。当接合模式在阻尼和振荡频率上一致时，可能会出现在共振现象方面更具体的模态相互作用。在本文中，使用蒙特卡罗 (MC) 模拟彻底研究了基于 RE 的 MG 的不确定功率注入对小信号稳定性的影响。从特征值分析可以看出，在 RE 不确定性下，临界模式的行为是随机且不可预测的。然而，临界模式的累积分布表明，来自 MG 系统的额外动力注入对提高系统稳定性产生了积极影响。所呈现的工作进一步讨论了 MG 的局部、区域间和控制模式之间的相互作用，因为系统参数使用一种称为模态相互作用指数 (MII) 的新指数发生变化。从几个案例研究中可以看出，MG 有助于减轻共振和模态相互作用。临界模式的累积分布表明，来自 MG 系统的额外功率注入对提高系统稳定性产生了积极影响。所呈现的工作进一步讨论了 MG 的局部、区域间和控制模式之间的相互作用，因为系统参数使用一种称为模态相互作用指数 (MII) 的新指数发生变化。从几个案例研究中可以看出，MG 有助于减轻共振和模态相互作用。临界模式的累积分布表明，来自 MG 系统的额外功率注入对提高系统稳定性产生了积极影响。所呈现的工作进一步讨论了 MG 的局部、区域间和控制模式之间的相互作用，因为系统参数使用一种称为模态相互作用指数 (MII) 的新指数发生变化。从几个案例研究中可以看出，MG 有助于减轻共振和模态相互作用。