Abstract
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.
Highlights
The renewable wind power generation technologies have been under rapid development in recent decades, and the most promising wind power solutions include the Doubly Fed Induction Generator(DFIG) based wind turbines and the Permanent Magnetic Synchronous Generator(PMSG) based wind turbines[1,2,3], which are typically used in wind farms
Considering that the DFIG system has both the Rotor Side Converter (RSC) and the Grid Side Converter(GSC), the active damping control strategy is implemented in the RSC by introducing a virtual impedance to effectively reshape the DFIG system impedance and to mitigate the HFR; on the other hand, the Grid Side Converter(GSC) introduces a closed-loop control of the PCC voltage using the 300Hz resonant controller to eliminate the lower order (5th and 7th) harmonic components at the PCC voltage
This paper has proposed an improved control strategy for a DFIG system considering both the HFR active damping and the improvement of PCC voltage quality
Summary
The renewable wind power generation technologies have been under rapid development in recent decades, and the most promising wind power solutions include the Doubly Fed Induction Generator(DFIG) based wind turbines and the Permanent Magnetic Synchronous Generator(PMSG) based wind turbines[1,2,3], which are typically used in wind farms. Considering that the DFIG system has both the Rotor Side Converter (RSC) and the Grid Side Converter(GSC), the active damping control strategy is implemented in the RSC by introducing a virtual impedance to effectively reshape the DFIG system impedance and to mitigate the HFR; on the other hand, the Grid Side Converter(GSC) introduces a closed-loop control of the PCC voltage using the 300Hz resonant controller to eliminate the lower order (5th and 7th) harmonic components at the PCC voltage Note that both of these two issues are related to the impedance of the weak grid.
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