Fundamental Stability Criteria for Feedback Systems

Foundations of VSC-induced Oscillation Stability Analysis : VSC-induced instabilities are primarily due to control interactions. The feedback control of a VSC aims to eliminate discrepancies between the control reference and objectives, such as injection current or PCC voltage. However, because of the feedback mechanism, minor disturbances from interactions between VSC control and the grid can be infinitely amplified, leading to loss of control. The fundamental stability criteria for assessing such instabilities are summarized and demonstrated.