Enhanced Low Voltage Ride Through (LVRT) Performance of Double-Fed Wind Generator (DFWG) with Grid-Forming (GFM) Capability

Optimizing the Low Voltage Ride Through (LVRT) performance of Doubly-fed Wind Generation (DFWG) has always been an important task to improve the operational reliability of wind turbines. For this purpose, this paper put forwards a novel DFWG with enhanced LVRT performance, which adopts Grid-forming (GFM) strategy based on virtual synchronous control. First of all, the topology of DFWG and the performance requirements of LVRT are presented respectively. Then, the mathematical modeling and control strategy designs of the grid side converter and rotor-side converter of DFWG, also with the GFM strategy are carried out, respectively. On the basis, a complete GFM-DFWG control structure is formed finally. A typical simulation case and analysis is carried out to by setting several types of disturbance or faults at different occurrence time, corresponding to various voltage drop depths. Simulation results reveal that GFM-DFWG can adapt to greater LVRT depth ranging from 0.2p.u. to 1.0p.u. caused by different disturbance or faults. Even when the grid-connected voltage of DFWG drops by 0.8p.u., it is still able to recover to 0.9p.u. within about 150ms, although the oscillation amplitude and recovery time of the major U-I parameters may have an expansion as the LVRT depth increases, thus verifying the excellent fast response and voltage support effect of GFM.