This paper presents a comprehensive small-signal stability analysis for synchronous generator (SG)-based microgrids (MGs) considering the control type of SGs and wide range of loading condition. The original aim is to evaluate the effect of loading conditions on the small-signal stability of droop-controlled and PQ-controlled SGs which has not been adequately addressed in the literature. To this purpose, complete state–space small-signal model of a typical medium voltage AC MG involving both droop-controlled and PQ-controlled SGs is developed. This facilitates stability studies by means of eigenvalue analysis. Results show that the small-signal stability behavior of droop-controlled SGs is different from that of PQ-controlled SGs. It is found that droop-controlled SGs show weaker stability or even instability in light loading condition. It is found that operation of PQ-controlled SGs in the presence of droop-controlled SGs can result in better stability of SG-based MG at light loading conditions. Effect of reference powers of PQ-controlled SGs on small-signal stability is also investigated. Moreover, the effect of Power System Stabilizer (PSS) on the damping of the weak stability or instability observed in low loading conditions of droop-controlled SG-based MGs is investigated. Time-domain simulations are used in order to verify the proposed theoretical analysis.

考虑到SG的控制类型和广泛的负载条件，本文针对基于SG的微电网（MG）进行了全面的小信号稳定性分析。最初的目的是评估加载条件对下垂控制和PQ控制的SG的小信号稳定性的影响，这在文献中尚未充分解决。为此，开发了一个典型的中压AC MG的完整状态-空间小信号模型，该模型同时涉及下垂控制和PQ控制的SG。这有助于通过特征值分析进行稳定性研究。结果表明，下降控制的SG的小信号稳定性行为不同于PQ控制的SG。已经发现，在轻载条件下，下垂控制的SGs表现出较弱的稳定性，甚至不稳定。发现在存在下垂控制的SG的情况下PQ控制的SG的操作可以在轻负载条件下导致基于SG的MG的更好的稳定性。还研究了PQ控制的SG的参考功率对小信号稳定性的影响。此外，研究了电力系统稳定器（PSS）对在低负载条件下所观测到的基于SG的MG MG的弱稳定性或不稳定性的阻尼作用。为了验证所提出的理论分析，使用了时域仿真。研究了电力系统稳定器（PSS）对在受压控制的SG型MG的低负载条件下观察到的弱稳定性或不稳定性的阻尼的影响。为了验证所提出的理论分析，使用了时域仿真。研究了电力系统稳定器（PSS）对在受压控制的SG型MG的低负载条件下观察到的弱稳定性或不稳定性的阻尼的影响。为了验证所提出的理论分析，使用了时域仿真。