Tuning Method of a Grid-Following Converter for the Extremely-Weak-Grid Connection

This letter proves that a grid-following converter can stably connect to a weak grid even short-circuit ratio (SCR) is 1. Root instability causes of this grid-following control are identified including fast control response, insufficient damping, and slow voltage support. A simple and effective tuning method is proposed to stabilize this connection. Three control modes are considered in this tuning method including current control, active power and voltage ($ PV$) control, and active power and reactive power ($ PQ$) control. The switching model of a two-level converter is used for the simulation validation.