Abstract
Motivated by recent years' resonance incidents in wind-integrated power systems, this paper investigates the resonance-induced harmonic distortion and stability issues in doubly fed induction generator (DFIG)-based offshore wind farm (OWF) with high-voltage direct current (HVDC) grid connection. To accurately capture the dynamic characteristics of DFIG-based wind farm, a comprehensive impedance modelling considering the detailed PI control loop and DC dynamics of wind turbine as well as the cable connections of the medium-voltage (MV) collector system is conducted. Through stepwise simulation verifications, aggregated modelling of MV collector system is proved to be suitable for wideband resonance analysis. On this basis, the resonance analysis regarding grid topology change and controller parameter variation is conducted and the impact of frequency coupling on subsynchronous resonance (SSR), middle- and high-frequency resonances is analyzed using the aggregated models derived from a practical HVDC connected DFIG-based OWF. The strength or degree of the frequency coupling between the sequence impedances of wind farm, which is induced by the asymmetrical converter control of wind turbines, is found to be dependent on the impedances of all the components of the system. Moreover, case studies are conducted to demonstrate the importance of including the frequency coupling in SSR stability assessment. Simulations in MATLAB / Simulink validate the modelling and resonance analysis.
Highlights
Over the last decade, many offshore wind farms (OWF) have been developed and integrated into grids through highvoltage direct current (HVDC) transmissions in the North and Baltic Seas
The interactions among wind turbines (WTs), HVDC converters and passive grid components can introduce a variety of inductive-capacitive (LC) resonances
On the resonances in wind-integrated power systems, the sub-synchronous resonance (SSR), middle- and highfrequency resonances between DFIGbased wind farm and AC grids, as well as the SSR between full-converter based wind farm and HVDC system have been intensively studied in recent years [7]-[13]
Summary
Many offshore wind farms (OWF) have been developed and integrated into grids through highvoltage direct current (HVDC) transmissions in the North and Baltic Seas. These modeling simplifications made to DFIG-based wind farm are not in favorable of the accurate identification of the resonances in the large-scale DFIG-based OWF with tens of widely distributed WTs. As for the impedance modelling of DFIG-based WT, most recent publications either have not incorporated the detailed double-loop PI control or neglect the DC side dynamics [17][19], which makes them incapable of capturing the exact low-frequency impedance responses of DFIG-based wind energy conversion system [20].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
