Resonance Active Damping and PCC Voltage Quality Improvement of DFIG System Connected to Parallel Compensated Grid

Under the connection to a weak grid, the Doubly Fed Induction Generator(DFIG) based wind power system has potential risk from two operational issues. The first issue is the High Frequency Resonance(HFR) mode due to the impedance interaction between the DFIG system and the weak grid. In order to ensure safe and reliable operation of the DFIG system, it is necessary to implement effective active damping strategies to mitigate the HFR. The second issue is low order voltage harmonic distortion at the Point of Common Coupling(PCC), where consequently the performance of other grid-connected devices may deteriorate. It could be advantageous that the DFIG system is able to improve the voltage quality at PCC by eliminating the low order harmonic components. In this paper, both of the above mentioned DFIG operational characters, i.e., active damping of HFR and the improvement of voltage quality at PCC, will be achieved by implementing advanced control strategies in the Rotor Side Converter(RSC) and the Grid Side Converter(GSC) respectively. Simulations are provided to verify the proposed control strategies for DFIG system connected to a weak grid.