Performance Improvement of VSG Dynamic Frequency Considering DC-Side Voltage Stability

Abstract

The Virtual Synchronous Generator (VSG) enhances the dynamic performance of voltage source converter (VSC) by emulating the characteristics of Synchronous Generators (SGs). When implemented within Multi-Terminal Direct Current (MTDC) systems, the VSG plays a crucial role in regulating DC voltage. In such applications, it is imperative for the VSG to precisely follow the power references set by external DC voltage control loops. However, a tradeoff is identified in current VSG implementations with fixed inertia control: a conflict between rapid reference tracking and high virtual inertia, resulting in a compromise between the transient response of active power and angular frequency. Furthermore, VSGs equipped with DC voltage cascade control exhibit a conflicting relationship between voltage droop coefficients and damping coefficients. Given these complexities, this paper analyzes the impact of VSG control parameters on power, angular frequency, and DC-side voltage stability. Subsequently, a comprehensive parameter adaptive method is proposed, encompassing inertia, damping, and droop parameters. The objective is to provide a swift power response and stable frequency support while maintaining a balance between power regulation and frequency regulation across diverse operational conditions.