Impact of Phase Angle Jump on DFIG Under LVRT Conditions: Challenges and Recommendations

Abstract

The increased penetration of wind power has made its low voltage ride through (LVRT) capability more crucial than ever. Currently, the LVRT performance of wind generators is verified using experimental voltage sags with different magnitudes and durations. The actual fault, however, also causes the phase angle jump (PAJ) of the grid voltage. In this paper, the impact of PAJ on the LVRT capability of doubly fed inductor generator (DFIG) under three-phase fault is analyzed. To achieve this, detailed analytical calculations and experimental verifications are conducted. The results demonstrate that the PAJ imposes more challenges on the LVRT by intensifying the rotor overcurrent through the natural stator flux. As a result, DFIGs that have passed the existing LVRT test may still fail to comply with the grid code requirements in practice. To tackle this issue, an improved test procedure is recommended. The new procedure considers the impedance angle of the target system as an additional test condition, thus can reveal the LVRT performance of DFIG under the potential PAJ.