Modeling and control of DFIG-based large offshore wind farm with HVDC-link integration

This paper presents an analysis and a power coordination technique for a Doubly-Fed Induction Generator (DFIG)-based wind farm with HVDC-link integration. Control and operation of both rotor-side converter (RSC) and grid-side converter (GSC) are analyzed. The RSC control loop tracks maximum wind power and controls stator flux linkage. The GSC control loop maintains stator terminal voltage and dc-link voltage between the RSC and the GSC. Line-commutated converter (LCC)-based HVDC transmission system is used for grid integration. The main control philosophy of the HVDC link is that firing angle of the rectifier is adjusted base on bus voltage magnitude. While the wind speed changes, through the rectifier control loop, dc voltage at the sending end of HVDC-link will vary with the firing angle, thus power balance of the AC and DC sides is achieved. Matlab/Simulink tests for a 2 MW DFIG with simplified HVDC-link model are performed to confirm the analysis and operation principle.