Transient Stability Enhancement Control for Virtual Synchronous Generator Controlled Isolated Power Grid

Virtual synchronous generator (VSG) controlled isolated power grid has been widely concerned because of its advantages of voltage support. However, in the presence of significant disturbance, the system would face the risk of transient instability like conventional power grid. As a recently developed control method, phase sequence exchange (PSE) can not only stabilize the system but also avoid additional reduction in system capacity and inertia. Nonetheless, PSE increases redundant power electronic devices into the grid. Therefore, this paper establishes a transient model for VSG-controlled isolated power grid initially. Based on this, a control method is proposed to realize the effect of PSE by reducing the power angle of VSG through power electronic control in the inverter, named as virtual phase sequence exchange (VPSE). This control method effectively avoids the need for external PSE devices while improving the transient stability. Furthermore, this paper investigates the VPSE technology through the extended equal area criterion (EEAC) and modern control theory, with results indicating that compared to PSE, VPSE has better transient control effects. Finally, the proposed scheme is verified by physical experiments on the real-time digital simulation platform (RTDS).