Transient Voltage Stability of Paralleled Synchronous and Virtual Synchronous Generators With Induction Motor Loads

Parallel operation of synchronous generators (SGs) and virtual synchronous generators (VSGs) is an important way to guarantee the safe operation of the microgrid in remote islands or rural areas. However, the system may experience transient voltage instability when a high penetration level of induction motor (IM) loads is connected. This paper considers the dynamics of SG and VSG to investigate the transient voltage stability of paralleled SG and VSG system with IM load. The effects of SG’s and VSG’s active power loops (APLs) are analyzed in detail due to the low inertia of microgrids and the power coupling introduced by the network impedance, which has not been well-explored in the prior research. The results show that the interaction of APLs between SG and VSG would deteriorate the transient voltage stability of the system. Moreover, critical clearance time (CCT) is employed to estimate the system stability. Based on the theoretical analysis, a control method is proposed to enhance the transient voltage stability of the system. The hardware-in-loop experiment is performed to verify the correctness of the theoretical analysis.