Explicit Impedance Modeling and Shaping of Grid-Connected Converters via an Enhanced PLL for Stabilizing the Weak Grid Connection

The voltage source converters (VSCs) are used to interface and control the renewable energy resources that integrated into power grids. However, a weak grid connection raises stability problem for synchronization of grid-feeding current-controlled VSCs (CCVSCs). This paper handles modeling controller design stabilizing CCVSCs. impedance modeling/shaping VSC has been recognized as an effective tool analyze dynamics VSC. But explicit accurate model CCVSC is required. Particularly, impact phase-locked loop (PLL) unit on complex. Therefore, at first, efficient developed while PLL rigorously considered through complex procedure results in explicit/accurate model. conduct passivity/weak analysis clarify underlying causes instability problems. Then, novel PLL, with in-loop low-pass filter (LPF) account harmonics/asymmetries, proposed enhanced characteristics using state feedback control. shaping method (with aid model) utilized gains. loops provide degrees freedom bandwidth considering current/power stabilize system under connection/distorted conditions. Simulation prove accuracy effectiveness models.