Power System Small-Signal Angular Stability Affected by Virtual Synchronous Generators

Abstract

This paper examines the small-signal angular stability of a power system affected by a virtual synchronous generator (VSG). The examination is based on an interconnected model with two subsystems. The VSG under the examination is modeled as the VSG subsystem. The rest of power system (ROPS) forms the other subsystem. Damping torque analysis is applied to indicate that when an oscillation mode of the VSG subsystem is in the proximity of an electromechanical oscillation mode of the ROPS subsystem on the complex plane, strong dynamic interactions are introduced by the VSG to decrease the small-signal angular stability of the power system. This implies that when the parameters of the VSG are set, modal proximity of the VSG to the electromechanical oscillation mode of the ROPS subsystem should be examined to avoid the detrimental impact of the VSG on power system small-signal angular stability. A method to evade the modal proximity is proposed in this paper for guiding the design of the VSG. Two example power systems with multiple VSGs for the wind power generation and transmission are presented. Study cases demonstrate and evaluate the analysis about the impact of modal proximity and proposed method for guiding the parameters setting of VSGs.