New Control Algorithms for the Distributed Generation Interface: Plug-and-play Integration and Robust Operation in Grid-connected and Micro-grid Modes

New control algorithms for the distributed generation (DG) interface are presented in this book. The proposed control algorithms are designed to realize a robust interface that guarantees plug- and-play integration and robust operation under the challenging uncertain nature of distribution systems and micro-grid operation mode. The control architecture of the proposed interface relies on the following subsystems: 1) a newly designed deadbeat current regulation scheme; 2) an adaptive discrete- time grid-voltage sensorless interfacing scheme; 3) a robust voltage control scheme featuring fast load voltage regulation and effective mitigation of fast voltage disturbances; and 4) a transient-based droop controller with adaptive transient-gains to constrain the drift of the low frequency modes in a conventional droop-controlled micro-grid. The overall robust DG interface facilitates a robust micro-grid operation and safe plug-and-play integration of DG units on existing distribution systems.