Abstract
A fault current limiter (FCL) may be applied to assist the low-voltage ride-through (LVRT) of a doubly fed induction generator (DFIG). FCLs with fixed impedance, lack the flexibility to adjust their impedance to adapt to different LVRT scenarios. The direct switch-in and -out of the fixed-impedance FCL yields transient electromagnetic oscillations in the DFIG, which need to be addressed. In this paper, a variable-impedance FCL is implemented at the stator side of the DFIG to assist its LVRT, and a novel methodology is proposed to control the impedance of the FCL, with which the stator current oscillation is effectively constrained and the smooth switch-out of the FCL is realized to avoid continued active power consumption of the FCL and to restore the DFIG to its pre-fault working condition. Analysis of the LVRT transient is carried out, which lays the foundation for the control methodology to determine the impedance of the FCL based on calculation of the optimization goal. The feasibility and effectiveness of the control to the variable-impedance FCL are verified by the numerical analysis results, which compare the LVRT simulation results with the application of the fixed-impedance and the variable-impedance FCLs.
Highlights
Due to their the merits, which include variable-speed constant-frequency operation capability and low investment requirement, doubly fed induction generator (DFIG) have become one of the most widely applied types of wind turbine generators (WTGs) [1,2,3]
A comprehensive review on the power transmission technology involved in offshore wind farms was carried out in [5], where the capabilities of WTGs to realize low-voltage ride-through (LVRT) and support the system frequency through the active power control were introduced in detail
The rotor-side converter (RSC) control of the DFIG was coordinated with the fault current limiter (FCL) implemented on the stator side
Summary
Due to their the merits, which include variable-speed constant-frequency operation capability and low investment requirement, DFIGs have become one of the most widely applied types of wind turbine generators (WTGs) [1,2,3]. To assist the LVRT of the DFIG, both software control schemes and hardware protection schemes have been developed [8] The former usually involves improvement to the converter control of the DFIG, e.g., adjusting the power/current control references according to the LVRT scenario [9], and eliminating the impact of stator flux oscillation yielded by the voltage dip on the converter control through feed-forward compensation [10,11]. The consumed active power constrains the capability of the DFIG to provide active power support for frequency stability during the LVRT [30], which has recently attracted attention from researchers With all this in mind, a control strategy to switch out the FCL needs to be developed, which utilizes the advantage of the variable-impedance FCL over fixed-impedance FCLs. The direct switch-out of the fixed-impedance FCL instantly causes another abrupt voltage change, once again yielding the stator current oscillations.
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
