Comprehensive small-signal stability analysis of islanded synchronous generator-based microgrids

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. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This paper presents a comprehensive small-signal stability analysis for synchronous generator-based microgrids, investigating the impact of loading conditions on droop-controlled and PQ-controlled SGs. It was found that droop-controlled SGs exhibit weaker stability, or even instability, in light loading conditions, while the operation of PQ-controlled SGs in such conditions can improve the stability of SG-based microgrids.